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The big update this time around is some excellent work from David Jander who went through the fast path and really eliminated overheads, meaning that we are seeing a huge reduction in the time spent between transfers for single threaded clients. Benchmarking has been coming out at about a halving of overhead which is clearly visible in system level usage that stresses SPI like some CAN and IIO applications, especially with small transfers. Thanks to David for taking the time to drill down into this and push the work upstream. Otherwise there's been a bunch of new device support and the usual - Optimisation of the fast path, particularly around the number and types of locking operations, from David Jander. - Support for Arbel NPCM845, HP GXP, Intel Meteor Lake and Thunder Bay, MediaTek MT8188 and MT8365, Microchip FPGAs, nVidia Tegra 241 and Samsung Exynos Auto v9 and 4210. -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmLnyFYACgkQJNaLcl1U h9AVpAf7BJI8NBQ659fyvfZkJDTlH8F3IjH4P3WpxMPCmTqvCZ5wBZyxwMIXGySE fe7iQw3PGXBcoEHxhYPR4ePp7LO5jHePybUzGCJBD0EYhlo9QVBpD5+P4t65c9z8 Hjpul428My4L7eUGl/29iv0Qzkyd3wnVPSsZqBCB6BOPTQ+hribs93Uj6rB4wmzF 9Vu4p+dqdGvdrIj3G2KpFRtKxhpnjUeD5l8Eq3rOPlEPjSKoHADHP2ZSpxoz5jfR 8L6C+RyADs7ro7X4hiIq1TGURVJ+6EkGDdc6O+Rj0S+PL7MCVOGR0ucPZMOVmNbJ 114wnOQNmVnGKHX0IBm7VIOMkfc7Dg== =5frj -----END PGP SIGNATURE----- Merge tag 'spi-v5.20' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi Pull spi updates from Mark Brown: "The big update this time around is some excellent work from David Jander who went through the fast path and really eliminated overheads, meaning that we are seeing a huge reduction in the time spent between transfers for single threaded clients. Benchmarking has been coming out at about a halving of overhead which is clearly visible in system level usage that stresses SPI like some CAN and IIO applications, especially with small transfers. Thanks to David for taking the time to drill down into this and push the work upstream. Otherwise there's been a bunch of new device support and the usual updates. - Optimisation of the fast path, particularly around the number and types of locking operations, from David Jander. - Support for Arbel NPCM845, HP GXP, Intel Meteor Lake and Thunder Bay, MediaTek MT8188 and MT8365, Microchip FPGAs, nVidia Tegra 241 and Samsung Exynos Auto v9 and 4210" * tag 'spi-v5.20' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi: (97 commits) MAINTAINERS: add spi support to GXP spi: dt-bindings: add documentation for hpe,gxp-spifi spi: spi-gxp: Add support for HPE GXP SoCs spi: a3700: support BE for AC5 SPI driver spi/panel: dt-bindings: drop CPHA and CPOL from common properties spi: bcm2835: enable shared interrupt support spi: dt-bindings: spi-controller: correct example indentation spi: dt-bindings: qcom,spi-geni-qcom: allow three interconnects spi: npcm-fiu: Add NPCM8XX support dt-binding: spi: Add npcm845 compatible to npcm-fiu document spi: npcm-fiu: Modify direct read dummy configuration spi: atmel: remove #ifdef CONFIG_{PM, SLEEP} spi: dt-bindings: Add compatible for MediaTek MT8188 spi: dt-bindings: mediatek,spi-mtk-nor: Update bindings for nor flash spi: dt-bindings: atmel,at91rm9200-spi: convert to json-schema spi: tegra20-slink: fix UAF in tegra_slink_remove() spi: Fix simplification of devm_spi_register_controller spi: microchip-core: switch to use dev_err_probe() spi: microchip-core: switch to use devm_spi_alloc_master() spi: microchip-core: fix UAF in mchp_corespi_remove() ...
1449 lines
42 KiB
C
1449 lines
42 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Driver for Broadcom BCM2835 SPI Controllers
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*
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* Copyright (C) 2012 Chris Boot
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* Copyright (C) 2013 Stephen Warren
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* Copyright (C) 2015 Martin Sperl
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*
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* This driver is inspired by:
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* spi-ath79.c, Copyright (C) 2009-2011 Gabor Juhos <juhosg@openwrt.org>
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* spi-atmel.c, Copyright (C) 2006 Atmel Corporation
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*/
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#include <linux/clk.h>
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#include <linux/completion.h>
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#include <linux/debugfs.h>
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#include <linux/delay.h>
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#include <linux/dma-mapping.h>
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#include <linux/dmaengine.h>
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#include <linux/err.h>
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#include <linux/interrupt.h>
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#include <linux/io.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/of_address.h>
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#include <linux/of_device.h>
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#include <linux/gpio/consumer.h>
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#include <linux/gpio/machine.h> /* FIXME: using chip internals */
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#include <linux/gpio/driver.h> /* FIXME: using chip internals */
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#include <linux/of_irq.h>
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#include <linux/spi/spi.h>
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/* SPI register offsets */
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#define BCM2835_SPI_CS 0x00
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#define BCM2835_SPI_FIFO 0x04
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#define BCM2835_SPI_CLK 0x08
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#define BCM2835_SPI_DLEN 0x0c
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#define BCM2835_SPI_LTOH 0x10
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#define BCM2835_SPI_DC 0x14
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/* Bitfields in CS */
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#define BCM2835_SPI_CS_LEN_LONG 0x02000000
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#define BCM2835_SPI_CS_DMA_LEN 0x01000000
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#define BCM2835_SPI_CS_CSPOL2 0x00800000
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#define BCM2835_SPI_CS_CSPOL1 0x00400000
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#define BCM2835_SPI_CS_CSPOL0 0x00200000
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#define BCM2835_SPI_CS_RXF 0x00100000
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#define BCM2835_SPI_CS_RXR 0x00080000
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#define BCM2835_SPI_CS_TXD 0x00040000
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#define BCM2835_SPI_CS_RXD 0x00020000
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#define BCM2835_SPI_CS_DONE 0x00010000
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#define BCM2835_SPI_CS_LEN 0x00002000
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#define BCM2835_SPI_CS_REN 0x00001000
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#define BCM2835_SPI_CS_ADCS 0x00000800
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#define BCM2835_SPI_CS_INTR 0x00000400
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#define BCM2835_SPI_CS_INTD 0x00000200
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#define BCM2835_SPI_CS_DMAEN 0x00000100
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#define BCM2835_SPI_CS_TA 0x00000080
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#define BCM2835_SPI_CS_CSPOL 0x00000040
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#define BCM2835_SPI_CS_CLEAR_RX 0x00000020
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#define BCM2835_SPI_CS_CLEAR_TX 0x00000010
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#define BCM2835_SPI_CS_CPOL 0x00000008
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#define BCM2835_SPI_CS_CPHA 0x00000004
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#define BCM2835_SPI_CS_CS_10 0x00000002
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#define BCM2835_SPI_CS_CS_01 0x00000001
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#define BCM2835_SPI_FIFO_SIZE 64
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#define BCM2835_SPI_FIFO_SIZE_3_4 48
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#define BCM2835_SPI_DMA_MIN_LENGTH 96
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#define BCM2835_SPI_MODE_BITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH \
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| SPI_NO_CS | SPI_3WIRE)
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#define DRV_NAME "spi-bcm2835"
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/* define polling limits */
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static unsigned int polling_limit_us = 30;
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module_param(polling_limit_us, uint, 0664);
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MODULE_PARM_DESC(polling_limit_us,
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"time in us to run a transfer in polling mode\n");
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/**
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* struct bcm2835_spi - BCM2835 SPI controller
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* @regs: base address of register map
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* @clk: core clock, divided to calculate serial clock
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* @clk_hz: core clock cached speed
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* @irq: interrupt, signals TX FIFO empty or RX FIFO ¾ full
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* @tfr: SPI transfer currently processed
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* @ctlr: SPI controller reverse lookup
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* @tx_buf: pointer whence next transmitted byte is read
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* @rx_buf: pointer where next received byte is written
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* @tx_len: remaining bytes to transmit
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* @rx_len: remaining bytes to receive
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* @tx_prologue: bytes transmitted without DMA if first TX sglist entry's
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* length is not a multiple of 4 (to overcome hardware limitation)
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* @rx_prologue: bytes received without DMA if first RX sglist entry's
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* length is not a multiple of 4 (to overcome hardware limitation)
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* @tx_spillover: whether @tx_prologue spills over to second TX sglist entry
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* @debugfs_dir: the debugfs directory - neede to remove debugfs when
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* unloading the module
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* @count_transfer_polling: count of how often polling mode is used
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* @count_transfer_irq: count of how often interrupt mode is used
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* @count_transfer_irq_after_polling: count of how often we fall back to
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* interrupt mode after starting in polling mode.
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* These are counted as well in @count_transfer_polling and
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* @count_transfer_irq
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* @count_transfer_dma: count how often dma mode is used
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* @slv: SPI slave currently selected
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* (used by bcm2835_spi_dma_tx_done() to write @clear_rx_cs)
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* @tx_dma_active: whether a TX DMA descriptor is in progress
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* @rx_dma_active: whether a RX DMA descriptor is in progress
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* (used by bcm2835_spi_dma_tx_done() to handle a race)
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* @fill_tx_desc: preallocated TX DMA descriptor used for RX-only transfers
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* (cyclically copies from zero page to TX FIFO)
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* @fill_tx_addr: bus address of zero page
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*/
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struct bcm2835_spi {
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void __iomem *regs;
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struct clk *clk;
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unsigned long clk_hz;
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int irq;
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struct spi_transfer *tfr;
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struct spi_controller *ctlr;
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const u8 *tx_buf;
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u8 *rx_buf;
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int tx_len;
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int rx_len;
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int tx_prologue;
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int rx_prologue;
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unsigned int tx_spillover;
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struct dentry *debugfs_dir;
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u64 count_transfer_polling;
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u64 count_transfer_irq;
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u64 count_transfer_irq_after_polling;
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u64 count_transfer_dma;
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struct bcm2835_spidev *slv;
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unsigned int tx_dma_active;
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unsigned int rx_dma_active;
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struct dma_async_tx_descriptor *fill_tx_desc;
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dma_addr_t fill_tx_addr;
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};
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/**
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* struct bcm2835_spidev - BCM2835 SPI slave
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* @prepare_cs: precalculated CS register value for ->prepare_message()
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* (uses slave-specific clock polarity and phase settings)
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* @clear_rx_desc: preallocated RX DMA descriptor used for TX-only transfers
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* (cyclically clears RX FIFO by writing @clear_rx_cs to CS register)
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* @clear_rx_addr: bus address of @clear_rx_cs
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* @clear_rx_cs: precalculated CS register value to clear RX FIFO
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* (uses slave-specific clock polarity and phase settings)
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*/
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struct bcm2835_spidev {
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u32 prepare_cs;
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struct dma_async_tx_descriptor *clear_rx_desc;
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dma_addr_t clear_rx_addr;
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u32 clear_rx_cs ____cacheline_aligned;
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};
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#if defined(CONFIG_DEBUG_FS)
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static void bcm2835_debugfs_create(struct bcm2835_spi *bs,
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const char *dname)
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{
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char name[64];
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struct dentry *dir;
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/* get full name */
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snprintf(name, sizeof(name), "spi-bcm2835-%s", dname);
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/* the base directory */
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dir = debugfs_create_dir(name, NULL);
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bs->debugfs_dir = dir;
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/* the counters */
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debugfs_create_u64("count_transfer_polling", 0444, dir,
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&bs->count_transfer_polling);
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debugfs_create_u64("count_transfer_irq", 0444, dir,
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&bs->count_transfer_irq);
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debugfs_create_u64("count_transfer_irq_after_polling", 0444, dir,
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&bs->count_transfer_irq_after_polling);
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debugfs_create_u64("count_transfer_dma", 0444, dir,
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&bs->count_transfer_dma);
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}
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static void bcm2835_debugfs_remove(struct bcm2835_spi *bs)
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{
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debugfs_remove_recursive(bs->debugfs_dir);
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bs->debugfs_dir = NULL;
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}
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#else
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static void bcm2835_debugfs_create(struct bcm2835_spi *bs,
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const char *dname)
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{
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}
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static void bcm2835_debugfs_remove(struct bcm2835_spi *bs)
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{
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}
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#endif /* CONFIG_DEBUG_FS */
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static inline u32 bcm2835_rd(struct bcm2835_spi *bs, unsigned int reg)
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{
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return readl(bs->regs + reg);
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}
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static inline void bcm2835_wr(struct bcm2835_spi *bs, unsigned int reg, u32 val)
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{
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writel(val, bs->regs + reg);
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}
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static inline void bcm2835_rd_fifo(struct bcm2835_spi *bs)
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{
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u8 byte;
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while ((bs->rx_len) &&
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(bcm2835_rd(bs, BCM2835_SPI_CS) & BCM2835_SPI_CS_RXD)) {
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byte = bcm2835_rd(bs, BCM2835_SPI_FIFO);
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if (bs->rx_buf)
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*bs->rx_buf++ = byte;
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bs->rx_len--;
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}
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}
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static inline void bcm2835_wr_fifo(struct bcm2835_spi *bs)
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{
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u8 byte;
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while ((bs->tx_len) &&
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(bcm2835_rd(bs, BCM2835_SPI_CS) & BCM2835_SPI_CS_TXD)) {
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byte = bs->tx_buf ? *bs->tx_buf++ : 0;
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bcm2835_wr(bs, BCM2835_SPI_FIFO, byte);
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bs->tx_len--;
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}
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}
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/**
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* bcm2835_rd_fifo_count() - blindly read exactly @count bytes from RX FIFO
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* @bs: BCM2835 SPI controller
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* @count: bytes to read from RX FIFO
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*
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* The caller must ensure that @bs->rx_len is greater than or equal to @count,
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* that the RX FIFO contains at least @count bytes and that the DMA Enable flag
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* in the CS register is set (such that a read from the FIFO register receives
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* 32-bit instead of just 8-bit). Moreover @bs->rx_buf must not be %NULL.
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*/
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static inline void bcm2835_rd_fifo_count(struct bcm2835_spi *bs, int count)
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{
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u32 val;
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int len;
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bs->rx_len -= count;
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do {
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val = bcm2835_rd(bs, BCM2835_SPI_FIFO);
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len = min(count, 4);
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memcpy(bs->rx_buf, &val, len);
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bs->rx_buf += len;
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count -= 4;
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} while (count > 0);
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}
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/**
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* bcm2835_wr_fifo_count() - blindly write exactly @count bytes to TX FIFO
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* @bs: BCM2835 SPI controller
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* @count: bytes to write to TX FIFO
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*
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* The caller must ensure that @bs->tx_len is greater than or equal to @count,
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* that the TX FIFO can accommodate @count bytes and that the DMA Enable flag
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* in the CS register is set (such that a write to the FIFO register transmits
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* 32-bit instead of just 8-bit).
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*/
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static inline void bcm2835_wr_fifo_count(struct bcm2835_spi *bs, int count)
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{
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u32 val;
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int len;
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bs->tx_len -= count;
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do {
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if (bs->tx_buf) {
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len = min(count, 4);
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memcpy(&val, bs->tx_buf, len);
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bs->tx_buf += len;
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} else {
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val = 0;
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}
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bcm2835_wr(bs, BCM2835_SPI_FIFO, val);
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count -= 4;
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} while (count > 0);
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}
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/**
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* bcm2835_wait_tx_fifo_empty() - busy-wait for TX FIFO to empty
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* @bs: BCM2835 SPI controller
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*
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* The caller must ensure that the RX FIFO can accommodate as many bytes
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* as have been written to the TX FIFO: Transmission is halted once the
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* RX FIFO is full, causing this function to spin forever.
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*/
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static inline void bcm2835_wait_tx_fifo_empty(struct bcm2835_spi *bs)
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{
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while (!(bcm2835_rd(bs, BCM2835_SPI_CS) & BCM2835_SPI_CS_DONE))
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cpu_relax();
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}
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/**
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* bcm2835_rd_fifo_blind() - blindly read up to @count bytes from RX FIFO
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* @bs: BCM2835 SPI controller
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* @count: bytes available for reading in RX FIFO
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*/
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static inline void bcm2835_rd_fifo_blind(struct bcm2835_spi *bs, int count)
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{
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u8 val;
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count = min(count, bs->rx_len);
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bs->rx_len -= count;
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do {
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val = bcm2835_rd(bs, BCM2835_SPI_FIFO);
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if (bs->rx_buf)
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*bs->rx_buf++ = val;
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} while (--count);
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}
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/**
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* bcm2835_wr_fifo_blind() - blindly write up to @count bytes to TX FIFO
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* @bs: BCM2835 SPI controller
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* @count: bytes available for writing in TX FIFO
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*/
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static inline void bcm2835_wr_fifo_blind(struct bcm2835_spi *bs, int count)
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{
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u8 val;
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count = min(count, bs->tx_len);
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bs->tx_len -= count;
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do {
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val = bs->tx_buf ? *bs->tx_buf++ : 0;
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bcm2835_wr(bs, BCM2835_SPI_FIFO, val);
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} while (--count);
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}
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static void bcm2835_spi_reset_hw(struct bcm2835_spi *bs)
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{
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u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
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/* Disable SPI interrupts and transfer */
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cs &= ~(BCM2835_SPI_CS_INTR |
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BCM2835_SPI_CS_INTD |
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BCM2835_SPI_CS_DMAEN |
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BCM2835_SPI_CS_TA);
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/*
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* Transmission sometimes breaks unless the DONE bit is written at the
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* end of every transfer. The spec says it's a RO bit. Either the
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* spec is wrong and the bit is actually of type RW1C, or it's a
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* hardware erratum.
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*/
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cs |= BCM2835_SPI_CS_DONE;
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/* and reset RX/TX FIFOS */
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cs |= BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX;
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/* and reset the SPI_HW */
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bcm2835_wr(bs, BCM2835_SPI_CS, cs);
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/* as well as DLEN */
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bcm2835_wr(bs, BCM2835_SPI_DLEN, 0);
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}
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static irqreturn_t bcm2835_spi_interrupt(int irq, void *dev_id)
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{
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struct bcm2835_spi *bs = dev_id;
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u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
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/* Bail out early if interrupts are not enabled */
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if (!(cs & BCM2835_SPI_CS_INTR))
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return IRQ_NONE;
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/*
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* An interrupt is signaled either if DONE is set (TX FIFO empty)
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* or if RXR is set (RX FIFO >= ¾ full).
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*/
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if (cs & BCM2835_SPI_CS_RXF)
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bcm2835_rd_fifo_blind(bs, BCM2835_SPI_FIFO_SIZE);
|
|
else if (cs & BCM2835_SPI_CS_RXR)
|
|
bcm2835_rd_fifo_blind(bs, BCM2835_SPI_FIFO_SIZE_3_4);
|
|
|
|
if (bs->tx_len && cs & BCM2835_SPI_CS_DONE)
|
|
bcm2835_wr_fifo_blind(bs, BCM2835_SPI_FIFO_SIZE);
|
|
|
|
/* Read as many bytes as possible from FIFO */
|
|
bcm2835_rd_fifo(bs);
|
|
/* Write as many bytes as possible to FIFO */
|
|
bcm2835_wr_fifo(bs);
|
|
|
|
if (!bs->rx_len) {
|
|
/* Transfer complete - reset SPI HW */
|
|
bcm2835_spi_reset_hw(bs);
|
|
/* wake up the framework */
|
|
spi_finalize_current_transfer(bs->ctlr);
|
|
}
|
|
|
|
return IRQ_HANDLED;
|
|
}
|
|
|
|
static int bcm2835_spi_transfer_one_irq(struct spi_controller *ctlr,
|
|
struct spi_device *spi,
|
|
struct spi_transfer *tfr,
|
|
u32 cs, bool fifo_empty)
|
|
{
|
|
struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr);
|
|
|
|
/* update usage statistics */
|
|
bs->count_transfer_irq++;
|
|
|
|
/*
|
|
* Enable HW block, but with interrupts still disabled.
|
|
* Otherwise the empty TX FIFO would immediately trigger an interrupt.
|
|
*/
|
|
bcm2835_wr(bs, BCM2835_SPI_CS, cs | BCM2835_SPI_CS_TA);
|
|
|
|
/* fill TX FIFO as much as possible */
|
|
if (fifo_empty)
|
|
bcm2835_wr_fifo_blind(bs, BCM2835_SPI_FIFO_SIZE);
|
|
bcm2835_wr_fifo(bs);
|
|
|
|
/* enable interrupts */
|
|
cs |= BCM2835_SPI_CS_INTR | BCM2835_SPI_CS_INTD | BCM2835_SPI_CS_TA;
|
|
bcm2835_wr(bs, BCM2835_SPI_CS, cs);
|
|
|
|
/* signal that we need to wait for completion */
|
|
return 1;
|
|
}
|
|
|
|
/**
|
|
* bcm2835_spi_transfer_prologue() - transfer first few bytes without DMA
|
|
* @ctlr: SPI master controller
|
|
* @tfr: SPI transfer
|
|
* @bs: BCM2835 SPI controller
|
|
* @cs: CS register
|
|
*
|
|
* A limitation in DMA mode is that the FIFO must be accessed in 4 byte chunks.
|
|
* Only the final write access is permitted to transmit less than 4 bytes, the
|
|
* SPI controller deduces its intended size from the DLEN register.
|
|
*
|
|
* If a TX or RX sglist contains multiple entries, one per page, and the first
|
|
* entry starts in the middle of a page, that first entry's length may not be
|
|
* a multiple of 4. Subsequent entries are fine because they span an entire
|
|
* page, hence do have a length that's a multiple of 4.
|
|
*
|
|
* This cannot happen with kmalloc'ed buffers (which is what most clients use)
|
|
* because they are contiguous in physical memory and therefore not split on
|
|
* page boundaries by spi_map_buf(). But it *can* happen with vmalloc'ed
|
|
* buffers.
|
|
*
|
|
* The DMA engine is incapable of combining sglist entries into a continuous
|
|
* stream of 4 byte chunks, it treats every entry separately: A TX entry is
|
|
* rounded up a to a multiple of 4 bytes by transmitting surplus bytes, an RX
|
|
* entry is rounded up by throwing away received bytes.
|
|
*
|
|
* Overcome this limitation by transferring the first few bytes without DMA:
|
|
* E.g. if the first TX sglist entry's length is 23 and the first RX's is 42,
|
|
* write 3 bytes to the TX FIFO but read only 2 bytes from the RX FIFO.
|
|
* The residue of 1 byte in the RX FIFO is picked up by DMA. Together with
|
|
* the rest of the first RX sglist entry it makes up a multiple of 4 bytes.
|
|
*
|
|
* Should the RX prologue be larger, say, 3 vis-à-vis a TX prologue of 1,
|
|
* write 1 + 4 = 5 bytes to the TX FIFO and read 3 bytes from the RX FIFO.
|
|
* Caution, the additional 4 bytes spill over to the second TX sglist entry
|
|
* if the length of the first is *exactly* 1.
|
|
*
|
|
* At most 6 bytes are written and at most 3 bytes read. Do we know the
|
|
* transfer has this many bytes? Yes, see BCM2835_SPI_DMA_MIN_LENGTH.
|
|
*
|
|
* The FIFO is normally accessed with 8-bit width by the CPU and 32-bit width
|
|
* by the DMA engine. Toggling the DMA Enable flag in the CS register switches
|
|
* the width but also garbles the FIFO's contents. The prologue must therefore
|
|
* be transmitted in 32-bit width to ensure that the following DMA transfer can
|
|
* pick up the residue in the RX FIFO in ungarbled form.
|
|
*/
|
|
static void bcm2835_spi_transfer_prologue(struct spi_controller *ctlr,
|
|
struct spi_transfer *tfr,
|
|
struct bcm2835_spi *bs,
|
|
u32 cs)
|
|
{
|
|
int tx_remaining;
|
|
|
|
bs->tfr = tfr;
|
|
bs->tx_prologue = 0;
|
|
bs->rx_prologue = 0;
|
|
bs->tx_spillover = false;
|
|
|
|
if (bs->tx_buf && !sg_is_last(&tfr->tx_sg.sgl[0]))
|
|
bs->tx_prologue = sg_dma_len(&tfr->tx_sg.sgl[0]) & 3;
|
|
|
|
if (bs->rx_buf && !sg_is_last(&tfr->rx_sg.sgl[0])) {
|
|
bs->rx_prologue = sg_dma_len(&tfr->rx_sg.sgl[0]) & 3;
|
|
|
|
if (bs->rx_prologue > bs->tx_prologue) {
|
|
if (!bs->tx_buf || sg_is_last(&tfr->tx_sg.sgl[0])) {
|
|
bs->tx_prologue = bs->rx_prologue;
|
|
} else {
|
|
bs->tx_prologue += 4;
|
|
bs->tx_spillover =
|
|
!(sg_dma_len(&tfr->tx_sg.sgl[0]) & ~3);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* rx_prologue > 0 implies tx_prologue > 0, so check only the latter */
|
|
if (!bs->tx_prologue)
|
|
return;
|
|
|
|
/* Write and read RX prologue. Adjust first entry in RX sglist. */
|
|
if (bs->rx_prologue) {
|
|
bcm2835_wr(bs, BCM2835_SPI_DLEN, bs->rx_prologue);
|
|
bcm2835_wr(bs, BCM2835_SPI_CS, cs | BCM2835_SPI_CS_TA
|
|
| BCM2835_SPI_CS_DMAEN);
|
|
bcm2835_wr_fifo_count(bs, bs->rx_prologue);
|
|
bcm2835_wait_tx_fifo_empty(bs);
|
|
bcm2835_rd_fifo_count(bs, bs->rx_prologue);
|
|
bcm2835_wr(bs, BCM2835_SPI_CS, cs | BCM2835_SPI_CS_CLEAR_RX
|
|
| BCM2835_SPI_CS_CLEAR_TX
|
|
| BCM2835_SPI_CS_DONE);
|
|
|
|
dma_sync_single_for_device(ctlr->dma_rx->device->dev,
|
|
sg_dma_address(&tfr->rx_sg.sgl[0]),
|
|
bs->rx_prologue, DMA_FROM_DEVICE);
|
|
|
|
sg_dma_address(&tfr->rx_sg.sgl[0]) += bs->rx_prologue;
|
|
sg_dma_len(&tfr->rx_sg.sgl[0]) -= bs->rx_prologue;
|
|
}
|
|
|
|
if (!bs->tx_buf)
|
|
return;
|
|
|
|
/*
|
|
* Write remaining TX prologue. Adjust first entry in TX sglist.
|
|
* Also adjust second entry if prologue spills over to it.
|
|
*/
|
|
tx_remaining = bs->tx_prologue - bs->rx_prologue;
|
|
if (tx_remaining) {
|
|
bcm2835_wr(bs, BCM2835_SPI_DLEN, tx_remaining);
|
|
bcm2835_wr(bs, BCM2835_SPI_CS, cs | BCM2835_SPI_CS_TA
|
|
| BCM2835_SPI_CS_DMAEN);
|
|
bcm2835_wr_fifo_count(bs, tx_remaining);
|
|
bcm2835_wait_tx_fifo_empty(bs);
|
|
bcm2835_wr(bs, BCM2835_SPI_CS, cs | BCM2835_SPI_CS_CLEAR_TX
|
|
| BCM2835_SPI_CS_DONE);
|
|
}
|
|
|
|
if (likely(!bs->tx_spillover)) {
|
|
sg_dma_address(&tfr->tx_sg.sgl[0]) += bs->tx_prologue;
|
|
sg_dma_len(&tfr->tx_sg.sgl[0]) -= bs->tx_prologue;
|
|
} else {
|
|
sg_dma_len(&tfr->tx_sg.sgl[0]) = 0;
|
|
sg_dma_address(&tfr->tx_sg.sgl[1]) += 4;
|
|
sg_dma_len(&tfr->tx_sg.sgl[1]) -= 4;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* bcm2835_spi_undo_prologue() - reconstruct original sglist state
|
|
* @bs: BCM2835 SPI controller
|
|
*
|
|
* Undo changes which were made to an SPI transfer's sglist when transmitting
|
|
* the prologue. This is necessary to ensure the same memory ranges are
|
|
* unmapped that were originally mapped.
|
|
*/
|
|
static void bcm2835_spi_undo_prologue(struct bcm2835_spi *bs)
|
|
{
|
|
struct spi_transfer *tfr = bs->tfr;
|
|
|
|
if (!bs->tx_prologue)
|
|
return;
|
|
|
|
if (bs->rx_prologue) {
|
|
sg_dma_address(&tfr->rx_sg.sgl[0]) -= bs->rx_prologue;
|
|
sg_dma_len(&tfr->rx_sg.sgl[0]) += bs->rx_prologue;
|
|
}
|
|
|
|
if (!bs->tx_buf)
|
|
goto out;
|
|
|
|
if (likely(!bs->tx_spillover)) {
|
|
sg_dma_address(&tfr->tx_sg.sgl[0]) -= bs->tx_prologue;
|
|
sg_dma_len(&tfr->tx_sg.sgl[0]) += bs->tx_prologue;
|
|
} else {
|
|
sg_dma_len(&tfr->tx_sg.sgl[0]) = bs->tx_prologue - 4;
|
|
sg_dma_address(&tfr->tx_sg.sgl[1]) -= 4;
|
|
sg_dma_len(&tfr->tx_sg.sgl[1]) += 4;
|
|
}
|
|
out:
|
|
bs->tx_prologue = 0;
|
|
}
|
|
|
|
/**
|
|
* bcm2835_spi_dma_rx_done() - callback for DMA RX channel
|
|
* @data: SPI master controller
|
|
*
|
|
* Used for bidirectional and RX-only transfers.
|
|
*/
|
|
static void bcm2835_spi_dma_rx_done(void *data)
|
|
{
|
|
struct spi_controller *ctlr = data;
|
|
struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr);
|
|
|
|
/* terminate tx-dma as we do not have an irq for it
|
|
* because when the rx dma will terminate and this callback
|
|
* is called the tx-dma must have finished - can't get to this
|
|
* situation otherwise...
|
|
*/
|
|
dmaengine_terminate_async(ctlr->dma_tx);
|
|
bs->tx_dma_active = false;
|
|
bs->rx_dma_active = false;
|
|
bcm2835_spi_undo_prologue(bs);
|
|
|
|
/* reset fifo and HW */
|
|
bcm2835_spi_reset_hw(bs);
|
|
|
|
/* and mark as completed */;
|
|
spi_finalize_current_transfer(ctlr);
|
|
}
|
|
|
|
/**
|
|
* bcm2835_spi_dma_tx_done() - callback for DMA TX channel
|
|
* @data: SPI master controller
|
|
*
|
|
* Used for TX-only transfers.
|
|
*/
|
|
static void bcm2835_spi_dma_tx_done(void *data)
|
|
{
|
|
struct spi_controller *ctlr = data;
|
|
struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr);
|
|
|
|
/* busy-wait for TX FIFO to empty */
|
|
while (!(bcm2835_rd(bs, BCM2835_SPI_CS) & BCM2835_SPI_CS_DONE))
|
|
bcm2835_wr(bs, BCM2835_SPI_CS, bs->slv->clear_rx_cs);
|
|
|
|
bs->tx_dma_active = false;
|
|
smp_wmb();
|
|
|
|
/*
|
|
* In case of a very short transfer, RX DMA may not have been
|
|
* issued yet. The onus is then on bcm2835_spi_transfer_one_dma()
|
|
* to terminate it immediately after issuing.
|
|
*/
|
|
if (cmpxchg(&bs->rx_dma_active, true, false))
|
|
dmaengine_terminate_async(ctlr->dma_rx);
|
|
|
|
bcm2835_spi_undo_prologue(bs);
|
|
bcm2835_spi_reset_hw(bs);
|
|
spi_finalize_current_transfer(ctlr);
|
|
}
|
|
|
|
/**
|
|
* bcm2835_spi_prepare_sg() - prepare and submit DMA descriptor for sglist
|
|
* @ctlr: SPI master controller
|
|
* @tfr: SPI transfer
|
|
* @bs: BCM2835 SPI controller
|
|
* @slv: BCM2835 SPI slave
|
|
* @is_tx: whether to submit DMA descriptor for TX or RX sglist
|
|
*
|
|
* Prepare and submit a DMA descriptor for the TX or RX sglist of @tfr.
|
|
* Return 0 on success or a negative error number.
|
|
*/
|
|
static int bcm2835_spi_prepare_sg(struct spi_controller *ctlr,
|
|
struct spi_transfer *tfr,
|
|
struct bcm2835_spi *bs,
|
|
struct bcm2835_spidev *slv,
|
|
bool is_tx)
|
|
{
|
|
struct dma_chan *chan;
|
|
struct scatterlist *sgl;
|
|
unsigned int nents;
|
|
enum dma_transfer_direction dir;
|
|
unsigned long flags;
|
|
|
|
struct dma_async_tx_descriptor *desc;
|
|
dma_cookie_t cookie;
|
|
|
|
if (is_tx) {
|
|
dir = DMA_MEM_TO_DEV;
|
|
chan = ctlr->dma_tx;
|
|
nents = tfr->tx_sg.nents;
|
|
sgl = tfr->tx_sg.sgl;
|
|
flags = tfr->rx_buf ? 0 : DMA_PREP_INTERRUPT;
|
|
} else {
|
|
dir = DMA_DEV_TO_MEM;
|
|
chan = ctlr->dma_rx;
|
|
nents = tfr->rx_sg.nents;
|
|
sgl = tfr->rx_sg.sgl;
|
|
flags = DMA_PREP_INTERRUPT;
|
|
}
|
|
/* prepare the channel */
|
|
desc = dmaengine_prep_slave_sg(chan, sgl, nents, dir, flags);
|
|
if (!desc)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* Completion is signaled by the RX channel for bidirectional and
|
|
* RX-only transfers; else by the TX channel for TX-only transfers.
|
|
*/
|
|
if (!is_tx) {
|
|
desc->callback = bcm2835_spi_dma_rx_done;
|
|
desc->callback_param = ctlr;
|
|
} else if (!tfr->rx_buf) {
|
|
desc->callback = bcm2835_spi_dma_tx_done;
|
|
desc->callback_param = ctlr;
|
|
bs->slv = slv;
|
|
}
|
|
|
|
/* submit it to DMA-engine */
|
|
cookie = dmaengine_submit(desc);
|
|
|
|
return dma_submit_error(cookie);
|
|
}
|
|
|
|
/**
|
|
* bcm2835_spi_transfer_one_dma() - perform SPI transfer using DMA engine
|
|
* @ctlr: SPI master controller
|
|
* @tfr: SPI transfer
|
|
* @slv: BCM2835 SPI slave
|
|
* @cs: CS register
|
|
*
|
|
* For *bidirectional* transfers (both tx_buf and rx_buf are non-%NULL), set up
|
|
* the TX and RX DMA channel to copy between memory and FIFO register.
|
|
*
|
|
* For *TX-only* transfers (rx_buf is %NULL), copying the RX FIFO's contents to
|
|
* memory is pointless. However not reading the RX FIFO isn't an option either
|
|
* because transmission is halted once it's full. As a workaround, cyclically
|
|
* clear the RX FIFO by setting the CLEAR_RX bit in the CS register.
|
|
*
|
|
* The CS register value is precalculated in bcm2835_spi_setup(). Normally
|
|
* this is called only once, on slave registration. A DMA descriptor to write
|
|
* this value is preallocated in bcm2835_dma_init(). All that's left to do
|
|
* when performing a TX-only transfer is to submit this descriptor to the RX
|
|
* DMA channel. Latency is thereby minimized. The descriptor does not
|
|
* generate any interrupts while running. It must be terminated once the
|
|
* TX DMA channel is done.
|
|
*
|
|
* Clearing the RX FIFO is paced by the DREQ signal. The signal is asserted
|
|
* when the RX FIFO becomes half full, i.e. 32 bytes. (Tuneable with the DC
|
|
* register.) Reading 32 bytes from the RX FIFO would normally require 8 bus
|
|
* accesses, whereas clearing it requires only 1 bus access. So an 8-fold
|
|
* reduction in bus traffic and thus energy consumption is achieved.
|
|
*
|
|
* For *RX-only* transfers (tx_buf is %NULL), fill the TX FIFO by cyclically
|
|
* copying from the zero page. The DMA descriptor to do this is preallocated
|
|
* in bcm2835_dma_init(). It must be terminated once the RX DMA channel is
|
|
* done and can then be reused.
|
|
*
|
|
* The BCM2835 DMA driver autodetects when a transaction copies from the zero
|
|
* page and utilizes the DMA controller's ability to synthesize zeroes instead
|
|
* of copying them from memory. This reduces traffic on the memory bus. The
|
|
* feature is not available on so-called "lite" channels, but normally TX DMA
|
|
* is backed by a full-featured channel.
|
|
*
|
|
* Zero-filling the TX FIFO is paced by the DREQ signal. Unfortunately the
|
|
* BCM2835 SPI controller continues to assert DREQ even after the DLEN register
|
|
* has been counted down to zero (hardware erratum). Thus, when the transfer
|
|
* has finished, the DMA engine zero-fills the TX FIFO until it is half full.
|
|
* (Tuneable with the DC register.) So up to 9 gratuitous bus accesses are
|
|
* performed at the end of an RX-only transfer.
|
|
*/
|
|
static int bcm2835_spi_transfer_one_dma(struct spi_controller *ctlr,
|
|
struct spi_transfer *tfr,
|
|
struct bcm2835_spidev *slv,
|
|
u32 cs)
|
|
{
|
|
struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr);
|
|
dma_cookie_t cookie;
|
|
int ret;
|
|
|
|
/* update usage statistics */
|
|
bs->count_transfer_dma++;
|
|
|
|
/*
|
|
* Transfer first few bytes without DMA if length of first TX or RX
|
|
* sglist entry is not a multiple of 4 bytes (hardware limitation).
|
|
*/
|
|
bcm2835_spi_transfer_prologue(ctlr, tfr, bs, cs);
|
|
|
|
/* setup tx-DMA */
|
|
if (bs->tx_buf) {
|
|
ret = bcm2835_spi_prepare_sg(ctlr, tfr, bs, slv, true);
|
|
} else {
|
|
cookie = dmaengine_submit(bs->fill_tx_desc);
|
|
ret = dma_submit_error(cookie);
|
|
}
|
|
if (ret)
|
|
goto err_reset_hw;
|
|
|
|
/* set the DMA length */
|
|
bcm2835_wr(bs, BCM2835_SPI_DLEN, bs->tx_len);
|
|
|
|
/* start the HW */
|
|
bcm2835_wr(bs, BCM2835_SPI_CS,
|
|
cs | BCM2835_SPI_CS_TA | BCM2835_SPI_CS_DMAEN);
|
|
|
|
bs->tx_dma_active = true;
|
|
smp_wmb();
|
|
|
|
/* start TX early */
|
|
dma_async_issue_pending(ctlr->dma_tx);
|
|
|
|
/* setup rx-DMA late - to run transfers while
|
|
* mapping of the rx buffers still takes place
|
|
* this saves 10us or more.
|
|
*/
|
|
if (bs->rx_buf) {
|
|
ret = bcm2835_spi_prepare_sg(ctlr, tfr, bs, slv, false);
|
|
} else {
|
|
cookie = dmaengine_submit(slv->clear_rx_desc);
|
|
ret = dma_submit_error(cookie);
|
|
}
|
|
if (ret) {
|
|
/* need to reset on errors */
|
|
dmaengine_terminate_sync(ctlr->dma_tx);
|
|
bs->tx_dma_active = false;
|
|
goto err_reset_hw;
|
|
}
|
|
|
|
/* start rx dma late */
|
|
dma_async_issue_pending(ctlr->dma_rx);
|
|
bs->rx_dma_active = true;
|
|
smp_mb();
|
|
|
|
/*
|
|
* In case of a very short TX-only transfer, bcm2835_spi_dma_tx_done()
|
|
* may run before RX DMA is issued. Terminate RX DMA if so.
|
|
*/
|
|
if (!bs->rx_buf && !bs->tx_dma_active &&
|
|
cmpxchg(&bs->rx_dma_active, true, false)) {
|
|
dmaengine_terminate_async(ctlr->dma_rx);
|
|
bcm2835_spi_reset_hw(bs);
|
|
}
|
|
|
|
/* wait for wakeup in framework */
|
|
return 1;
|
|
|
|
err_reset_hw:
|
|
bcm2835_spi_reset_hw(bs);
|
|
bcm2835_spi_undo_prologue(bs);
|
|
return ret;
|
|
}
|
|
|
|
static bool bcm2835_spi_can_dma(struct spi_controller *ctlr,
|
|
struct spi_device *spi,
|
|
struct spi_transfer *tfr)
|
|
{
|
|
/* we start DMA efforts only on bigger transfers */
|
|
if (tfr->len < BCM2835_SPI_DMA_MIN_LENGTH)
|
|
return false;
|
|
|
|
/* return OK */
|
|
return true;
|
|
}
|
|
|
|
static void bcm2835_dma_release(struct spi_controller *ctlr,
|
|
struct bcm2835_spi *bs)
|
|
{
|
|
if (ctlr->dma_tx) {
|
|
dmaengine_terminate_sync(ctlr->dma_tx);
|
|
|
|
if (bs->fill_tx_desc)
|
|
dmaengine_desc_free(bs->fill_tx_desc);
|
|
|
|
if (bs->fill_tx_addr)
|
|
dma_unmap_page_attrs(ctlr->dma_tx->device->dev,
|
|
bs->fill_tx_addr, sizeof(u32),
|
|
DMA_TO_DEVICE,
|
|
DMA_ATTR_SKIP_CPU_SYNC);
|
|
|
|
dma_release_channel(ctlr->dma_tx);
|
|
ctlr->dma_tx = NULL;
|
|
}
|
|
|
|
if (ctlr->dma_rx) {
|
|
dmaengine_terminate_sync(ctlr->dma_rx);
|
|
dma_release_channel(ctlr->dma_rx);
|
|
ctlr->dma_rx = NULL;
|
|
}
|
|
}
|
|
|
|
static int bcm2835_dma_init(struct spi_controller *ctlr, struct device *dev,
|
|
struct bcm2835_spi *bs)
|
|
{
|
|
struct dma_slave_config slave_config;
|
|
const __be32 *addr;
|
|
dma_addr_t dma_reg_base;
|
|
int ret;
|
|
|
|
/* base address in dma-space */
|
|
addr = of_get_address(ctlr->dev.of_node, 0, NULL, NULL);
|
|
if (!addr) {
|
|
dev_err(dev, "could not get DMA-register address - not using dma mode\n");
|
|
/* Fall back to interrupt mode */
|
|
return 0;
|
|
}
|
|
dma_reg_base = be32_to_cpup(addr);
|
|
|
|
/* get tx/rx dma */
|
|
ctlr->dma_tx = dma_request_chan(dev, "tx");
|
|
if (IS_ERR(ctlr->dma_tx)) {
|
|
dev_err(dev, "no tx-dma configuration found - not using dma mode\n");
|
|
ret = PTR_ERR(ctlr->dma_tx);
|
|
ctlr->dma_tx = NULL;
|
|
goto err;
|
|
}
|
|
ctlr->dma_rx = dma_request_chan(dev, "rx");
|
|
if (IS_ERR(ctlr->dma_rx)) {
|
|
dev_err(dev, "no rx-dma configuration found - not using dma mode\n");
|
|
ret = PTR_ERR(ctlr->dma_rx);
|
|
ctlr->dma_rx = NULL;
|
|
goto err_release;
|
|
}
|
|
|
|
/*
|
|
* The TX DMA channel either copies a transfer's TX buffer to the FIFO
|
|
* or, in case of an RX-only transfer, cyclically copies from the zero
|
|
* page to the FIFO using a preallocated, reusable descriptor.
|
|
*/
|
|
slave_config.dst_addr = (u32)(dma_reg_base + BCM2835_SPI_FIFO);
|
|
slave_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
|
|
|
|
ret = dmaengine_slave_config(ctlr->dma_tx, &slave_config);
|
|
if (ret)
|
|
goto err_config;
|
|
|
|
bs->fill_tx_addr = dma_map_page_attrs(ctlr->dma_tx->device->dev,
|
|
ZERO_PAGE(0), 0, sizeof(u32),
|
|
DMA_TO_DEVICE,
|
|
DMA_ATTR_SKIP_CPU_SYNC);
|
|
if (dma_mapping_error(ctlr->dma_tx->device->dev, bs->fill_tx_addr)) {
|
|
dev_err(dev, "cannot map zero page - not using DMA mode\n");
|
|
bs->fill_tx_addr = 0;
|
|
ret = -ENOMEM;
|
|
goto err_release;
|
|
}
|
|
|
|
bs->fill_tx_desc = dmaengine_prep_dma_cyclic(ctlr->dma_tx,
|
|
bs->fill_tx_addr,
|
|
sizeof(u32), 0,
|
|
DMA_MEM_TO_DEV, 0);
|
|
if (!bs->fill_tx_desc) {
|
|
dev_err(dev, "cannot prepare fill_tx_desc - not using DMA mode\n");
|
|
ret = -ENOMEM;
|
|
goto err_release;
|
|
}
|
|
|
|
ret = dmaengine_desc_set_reuse(bs->fill_tx_desc);
|
|
if (ret) {
|
|
dev_err(dev, "cannot reuse fill_tx_desc - not using DMA mode\n");
|
|
goto err_release;
|
|
}
|
|
|
|
/*
|
|
* The RX DMA channel is used bidirectionally: It either reads the
|
|
* RX FIFO or, in case of a TX-only transfer, cyclically writes a
|
|
* precalculated value to the CS register to clear the RX FIFO.
|
|
*/
|
|
slave_config.src_addr = (u32)(dma_reg_base + BCM2835_SPI_FIFO);
|
|
slave_config.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
|
|
slave_config.dst_addr = (u32)(dma_reg_base + BCM2835_SPI_CS);
|
|
slave_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
|
|
|
|
ret = dmaengine_slave_config(ctlr->dma_rx, &slave_config);
|
|
if (ret)
|
|
goto err_config;
|
|
|
|
/* all went well, so set can_dma */
|
|
ctlr->can_dma = bcm2835_spi_can_dma;
|
|
|
|
return 0;
|
|
|
|
err_config:
|
|
dev_err(dev, "issue configuring dma: %d - not using DMA mode\n",
|
|
ret);
|
|
err_release:
|
|
bcm2835_dma_release(ctlr, bs);
|
|
err:
|
|
/*
|
|
* Only report error for deferred probing, otherwise fall back to
|
|
* interrupt mode
|
|
*/
|
|
if (ret != -EPROBE_DEFER)
|
|
ret = 0;
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int bcm2835_spi_transfer_one_poll(struct spi_controller *ctlr,
|
|
struct spi_device *spi,
|
|
struct spi_transfer *tfr,
|
|
u32 cs)
|
|
{
|
|
struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr);
|
|
unsigned long timeout;
|
|
|
|
/* update usage statistics */
|
|
bs->count_transfer_polling++;
|
|
|
|
/* enable HW block without interrupts */
|
|
bcm2835_wr(bs, BCM2835_SPI_CS, cs | BCM2835_SPI_CS_TA);
|
|
|
|
/* fill in the fifo before timeout calculations
|
|
* if we are interrupted here, then the data is
|
|
* getting transferred by the HW while we are interrupted
|
|
*/
|
|
bcm2835_wr_fifo_blind(bs, BCM2835_SPI_FIFO_SIZE);
|
|
|
|
/* set the timeout to at least 2 jiffies */
|
|
timeout = jiffies + 2 + HZ * polling_limit_us / 1000000;
|
|
|
|
/* loop until finished the transfer */
|
|
while (bs->rx_len) {
|
|
/* fill in tx fifo with remaining data */
|
|
bcm2835_wr_fifo(bs);
|
|
|
|
/* read from fifo as much as possible */
|
|
bcm2835_rd_fifo(bs);
|
|
|
|
/* if there is still data pending to read
|
|
* then check the timeout
|
|
*/
|
|
if (bs->rx_len && time_after(jiffies, timeout)) {
|
|
dev_dbg_ratelimited(&spi->dev,
|
|
"timeout period reached: jiffies: %lu remaining tx/rx: %d/%d - falling back to interrupt mode\n",
|
|
jiffies - timeout,
|
|
bs->tx_len, bs->rx_len);
|
|
/* fall back to interrupt mode */
|
|
|
|
/* update usage statistics */
|
|
bs->count_transfer_irq_after_polling++;
|
|
|
|
return bcm2835_spi_transfer_one_irq(ctlr, spi,
|
|
tfr, cs, false);
|
|
}
|
|
}
|
|
|
|
/* Transfer complete - reset SPI HW */
|
|
bcm2835_spi_reset_hw(bs);
|
|
/* and return without waiting for completion */
|
|
return 0;
|
|
}
|
|
|
|
static int bcm2835_spi_transfer_one(struct spi_controller *ctlr,
|
|
struct spi_device *spi,
|
|
struct spi_transfer *tfr)
|
|
{
|
|
struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr);
|
|
struct bcm2835_spidev *slv = spi_get_ctldata(spi);
|
|
unsigned long spi_hz, cdiv;
|
|
unsigned long hz_per_byte, byte_limit;
|
|
u32 cs = slv->prepare_cs;
|
|
|
|
/* set clock */
|
|
spi_hz = tfr->speed_hz;
|
|
|
|
if (spi_hz >= bs->clk_hz / 2) {
|
|
cdiv = 2; /* clk_hz/2 is the fastest we can go */
|
|
} else if (spi_hz) {
|
|
/* CDIV must be a multiple of two */
|
|
cdiv = DIV_ROUND_UP(bs->clk_hz, spi_hz);
|
|
cdiv += (cdiv % 2);
|
|
|
|
if (cdiv >= 65536)
|
|
cdiv = 0; /* 0 is the slowest we can go */
|
|
} else {
|
|
cdiv = 0; /* 0 is the slowest we can go */
|
|
}
|
|
tfr->effective_speed_hz = cdiv ? (bs->clk_hz / cdiv) : (bs->clk_hz / 65536);
|
|
bcm2835_wr(bs, BCM2835_SPI_CLK, cdiv);
|
|
|
|
/* handle all the 3-wire mode */
|
|
if (spi->mode & SPI_3WIRE && tfr->rx_buf)
|
|
cs |= BCM2835_SPI_CS_REN;
|
|
|
|
/* set transmit buffers and length */
|
|
bs->tx_buf = tfr->tx_buf;
|
|
bs->rx_buf = tfr->rx_buf;
|
|
bs->tx_len = tfr->len;
|
|
bs->rx_len = tfr->len;
|
|
|
|
/* Calculate the estimated time in us the transfer runs. Note that
|
|
* there is 1 idle clocks cycles after each byte getting transferred
|
|
* so we have 9 cycles/byte. This is used to find the number of Hz
|
|
* per byte per polling limit. E.g., we can transfer 1 byte in 30 us
|
|
* per 300,000 Hz of bus clock.
|
|
*/
|
|
hz_per_byte = polling_limit_us ? (9 * 1000000) / polling_limit_us : 0;
|
|
byte_limit = hz_per_byte ? tfr->effective_speed_hz / hz_per_byte : 1;
|
|
|
|
/* run in polling mode for short transfers */
|
|
if (tfr->len < byte_limit)
|
|
return bcm2835_spi_transfer_one_poll(ctlr, spi, tfr, cs);
|
|
|
|
/* run in dma mode if conditions are right
|
|
* Note that unlike poll or interrupt mode DMA mode does not have
|
|
* this 1 idle clock cycle pattern but runs the spi clock without gaps
|
|
*/
|
|
if (ctlr->can_dma && bcm2835_spi_can_dma(ctlr, spi, tfr))
|
|
return bcm2835_spi_transfer_one_dma(ctlr, tfr, slv, cs);
|
|
|
|
/* run in interrupt-mode */
|
|
return bcm2835_spi_transfer_one_irq(ctlr, spi, tfr, cs, true);
|
|
}
|
|
|
|
static int bcm2835_spi_prepare_message(struct spi_controller *ctlr,
|
|
struct spi_message *msg)
|
|
{
|
|
struct spi_device *spi = msg->spi;
|
|
struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr);
|
|
struct bcm2835_spidev *slv = spi_get_ctldata(spi);
|
|
int ret;
|
|
|
|
if (ctlr->can_dma) {
|
|
/*
|
|
* DMA transfers are limited to 16 bit (0 to 65535 bytes) by
|
|
* the SPI HW due to DLEN. Split up transfers (32-bit FIFO
|
|
* aligned) if the limit is exceeded.
|
|
*/
|
|
ret = spi_split_transfers_maxsize(ctlr, msg, 65532,
|
|
GFP_KERNEL | GFP_DMA);
|
|
if (ret)
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Set up clock polarity before spi_transfer_one_message() asserts
|
|
* chip select to avoid a gratuitous clock signal edge.
|
|
*/
|
|
bcm2835_wr(bs, BCM2835_SPI_CS, slv->prepare_cs);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void bcm2835_spi_handle_err(struct spi_controller *ctlr,
|
|
struct spi_message *msg)
|
|
{
|
|
struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr);
|
|
|
|
/* if an error occurred and we have an active dma, then terminate */
|
|
if (ctlr->dma_tx) {
|
|
dmaengine_terminate_sync(ctlr->dma_tx);
|
|
bs->tx_dma_active = false;
|
|
}
|
|
if (ctlr->dma_rx) {
|
|
dmaengine_terminate_sync(ctlr->dma_rx);
|
|
bs->rx_dma_active = false;
|
|
}
|
|
bcm2835_spi_undo_prologue(bs);
|
|
|
|
/* and reset */
|
|
bcm2835_spi_reset_hw(bs);
|
|
}
|
|
|
|
static int chip_match_name(struct gpio_chip *chip, void *data)
|
|
{
|
|
return !strcmp(chip->label, data);
|
|
}
|
|
|
|
static void bcm2835_spi_cleanup(struct spi_device *spi)
|
|
{
|
|
struct bcm2835_spidev *slv = spi_get_ctldata(spi);
|
|
struct spi_controller *ctlr = spi->controller;
|
|
|
|
if (slv->clear_rx_desc)
|
|
dmaengine_desc_free(slv->clear_rx_desc);
|
|
|
|
if (slv->clear_rx_addr)
|
|
dma_unmap_single(ctlr->dma_rx->device->dev,
|
|
slv->clear_rx_addr,
|
|
sizeof(u32),
|
|
DMA_TO_DEVICE);
|
|
|
|
kfree(slv);
|
|
}
|
|
|
|
static int bcm2835_spi_setup_dma(struct spi_controller *ctlr,
|
|
struct spi_device *spi,
|
|
struct bcm2835_spi *bs,
|
|
struct bcm2835_spidev *slv)
|
|
{
|
|
int ret;
|
|
|
|
if (!ctlr->dma_rx)
|
|
return 0;
|
|
|
|
slv->clear_rx_addr = dma_map_single(ctlr->dma_rx->device->dev,
|
|
&slv->clear_rx_cs,
|
|
sizeof(u32),
|
|
DMA_TO_DEVICE);
|
|
if (dma_mapping_error(ctlr->dma_rx->device->dev, slv->clear_rx_addr)) {
|
|
dev_err(&spi->dev, "cannot map clear_rx_cs\n");
|
|
slv->clear_rx_addr = 0;
|
|
return -ENOMEM;
|
|
}
|
|
|
|
slv->clear_rx_desc = dmaengine_prep_dma_cyclic(ctlr->dma_rx,
|
|
slv->clear_rx_addr,
|
|
sizeof(u32), 0,
|
|
DMA_MEM_TO_DEV, 0);
|
|
if (!slv->clear_rx_desc) {
|
|
dev_err(&spi->dev, "cannot prepare clear_rx_desc\n");
|
|
return -ENOMEM;
|
|
}
|
|
|
|
ret = dmaengine_desc_set_reuse(slv->clear_rx_desc);
|
|
if (ret) {
|
|
dev_err(&spi->dev, "cannot reuse clear_rx_desc\n");
|
|
return ret;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int bcm2835_spi_setup(struct spi_device *spi)
|
|
{
|
|
struct spi_controller *ctlr = spi->controller;
|
|
struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr);
|
|
struct bcm2835_spidev *slv = spi_get_ctldata(spi);
|
|
struct gpio_chip *chip;
|
|
int ret;
|
|
u32 cs;
|
|
|
|
if (!slv) {
|
|
slv = kzalloc(ALIGN(sizeof(*slv), dma_get_cache_alignment()),
|
|
GFP_KERNEL);
|
|
if (!slv)
|
|
return -ENOMEM;
|
|
|
|
spi_set_ctldata(spi, slv);
|
|
|
|
ret = bcm2835_spi_setup_dma(ctlr, spi, bs, slv);
|
|
if (ret)
|
|
goto err_cleanup;
|
|
}
|
|
|
|
/*
|
|
* Precalculate SPI slave's CS register value for ->prepare_message():
|
|
* The driver always uses software-controlled GPIO chip select, hence
|
|
* set the hardware-controlled native chip select to an invalid value
|
|
* to prevent it from interfering.
|
|
*/
|
|
cs = BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01;
|
|
if (spi->mode & SPI_CPOL)
|
|
cs |= BCM2835_SPI_CS_CPOL;
|
|
if (spi->mode & SPI_CPHA)
|
|
cs |= BCM2835_SPI_CS_CPHA;
|
|
slv->prepare_cs = cs;
|
|
|
|
/*
|
|
* Precalculate SPI slave's CS register value to clear RX FIFO
|
|
* in case of a TX-only DMA transfer.
|
|
*/
|
|
if (ctlr->dma_rx) {
|
|
slv->clear_rx_cs = cs | BCM2835_SPI_CS_TA |
|
|
BCM2835_SPI_CS_DMAEN |
|
|
BCM2835_SPI_CS_CLEAR_RX;
|
|
dma_sync_single_for_device(ctlr->dma_rx->device->dev,
|
|
slv->clear_rx_addr,
|
|
sizeof(u32),
|
|
DMA_TO_DEVICE);
|
|
}
|
|
|
|
/*
|
|
* sanity checking the native-chipselects
|
|
*/
|
|
if (spi->mode & SPI_NO_CS)
|
|
return 0;
|
|
/*
|
|
* The SPI core has successfully requested the CS GPIO line from the
|
|
* device tree, so we are done.
|
|
*/
|
|
if (spi->cs_gpiod)
|
|
return 0;
|
|
if (spi->chip_select > 1) {
|
|
/* error in the case of native CS requested with CS > 1
|
|
* officially there is a CS2, but it is not documented
|
|
* which GPIO is connected with that...
|
|
*/
|
|
dev_err(&spi->dev,
|
|
"setup: only two native chip-selects are supported\n");
|
|
ret = -EINVAL;
|
|
goto err_cleanup;
|
|
}
|
|
|
|
/*
|
|
* Translate native CS to GPIO
|
|
*
|
|
* FIXME: poking around in the gpiolib internals like this is
|
|
* not very good practice. Find a way to locate the real problem
|
|
* and fix it. Why is the GPIO descriptor in spi->cs_gpiod
|
|
* sometimes not assigned correctly? Erroneous device trees?
|
|
*/
|
|
|
|
/* get the gpio chip for the base */
|
|
chip = gpiochip_find("pinctrl-bcm2835", chip_match_name);
|
|
if (!chip)
|
|
return 0;
|
|
|
|
spi->cs_gpiod = gpiochip_request_own_desc(chip, 8 - spi->chip_select,
|
|
DRV_NAME,
|
|
GPIO_LOOKUP_FLAGS_DEFAULT,
|
|
GPIOD_OUT_LOW);
|
|
if (IS_ERR(spi->cs_gpiod)) {
|
|
ret = PTR_ERR(spi->cs_gpiod);
|
|
goto err_cleanup;
|
|
}
|
|
|
|
/* and set up the "mode" and level */
|
|
dev_info(&spi->dev, "setting up native-CS%i to use GPIO\n",
|
|
spi->chip_select);
|
|
|
|
return 0;
|
|
|
|
err_cleanup:
|
|
bcm2835_spi_cleanup(spi);
|
|
return ret;
|
|
}
|
|
|
|
static int bcm2835_spi_probe(struct platform_device *pdev)
|
|
{
|
|
struct spi_controller *ctlr;
|
|
struct bcm2835_spi *bs;
|
|
int err;
|
|
|
|
ctlr = devm_spi_alloc_master(&pdev->dev, sizeof(*bs));
|
|
if (!ctlr)
|
|
return -ENOMEM;
|
|
|
|
platform_set_drvdata(pdev, ctlr);
|
|
|
|
ctlr->use_gpio_descriptors = true;
|
|
ctlr->mode_bits = BCM2835_SPI_MODE_BITS;
|
|
ctlr->bits_per_word_mask = SPI_BPW_MASK(8);
|
|
ctlr->num_chipselect = 3;
|
|
ctlr->setup = bcm2835_spi_setup;
|
|
ctlr->cleanup = bcm2835_spi_cleanup;
|
|
ctlr->transfer_one = bcm2835_spi_transfer_one;
|
|
ctlr->handle_err = bcm2835_spi_handle_err;
|
|
ctlr->prepare_message = bcm2835_spi_prepare_message;
|
|
ctlr->dev.of_node = pdev->dev.of_node;
|
|
|
|
bs = spi_controller_get_devdata(ctlr);
|
|
bs->ctlr = ctlr;
|
|
|
|
bs->regs = devm_platform_ioremap_resource(pdev, 0);
|
|
if (IS_ERR(bs->regs))
|
|
return PTR_ERR(bs->regs);
|
|
|
|
bs->clk = devm_clk_get(&pdev->dev, NULL);
|
|
if (IS_ERR(bs->clk))
|
|
return dev_err_probe(&pdev->dev, PTR_ERR(bs->clk),
|
|
"could not get clk\n");
|
|
|
|
ctlr->max_speed_hz = clk_get_rate(bs->clk) / 2;
|
|
|
|
bs->irq = platform_get_irq(pdev, 0);
|
|
if (bs->irq <= 0)
|
|
return bs->irq ? bs->irq : -ENODEV;
|
|
|
|
clk_prepare_enable(bs->clk);
|
|
bs->clk_hz = clk_get_rate(bs->clk);
|
|
|
|
err = bcm2835_dma_init(ctlr, &pdev->dev, bs);
|
|
if (err)
|
|
goto out_clk_disable;
|
|
|
|
/* initialise the hardware with the default polarities */
|
|
bcm2835_wr(bs, BCM2835_SPI_CS,
|
|
BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX);
|
|
|
|
err = devm_request_irq(&pdev->dev, bs->irq, bcm2835_spi_interrupt,
|
|
IRQF_SHARED, dev_name(&pdev->dev), bs);
|
|
if (err) {
|
|
dev_err(&pdev->dev, "could not request IRQ: %d\n", err);
|
|
goto out_dma_release;
|
|
}
|
|
|
|
err = spi_register_controller(ctlr);
|
|
if (err) {
|
|
dev_err(&pdev->dev, "could not register SPI controller: %d\n",
|
|
err);
|
|
goto out_dma_release;
|
|
}
|
|
|
|
bcm2835_debugfs_create(bs, dev_name(&pdev->dev));
|
|
|
|
return 0;
|
|
|
|
out_dma_release:
|
|
bcm2835_dma_release(ctlr, bs);
|
|
out_clk_disable:
|
|
clk_disable_unprepare(bs->clk);
|
|
return err;
|
|
}
|
|
|
|
static int bcm2835_spi_remove(struct platform_device *pdev)
|
|
{
|
|
struct spi_controller *ctlr = platform_get_drvdata(pdev);
|
|
struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr);
|
|
|
|
bcm2835_debugfs_remove(bs);
|
|
|
|
spi_unregister_controller(ctlr);
|
|
|
|
bcm2835_dma_release(ctlr, bs);
|
|
|
|
/* Clear FIFOs, and disable the HW block */
|
|
bcm2835_wr(bs, BCM2835_SPI_CS,
|
|
BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX);
|
|
|
|
clk_disable_unprepare(bs->clk);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void bcm2835_spi_shutdown(struct platform_device *pdev)
|
|
{
|
|
int ret;
|
|
|
|
ret = bcm2835_spi_remove(pdev);
|
|
if (ret)
|
|
dev_err(&pdev->dev, "failed to shutdown\n");
|
|
}
|
|
|
|
static const struct of_device_id bcm2835_spi_match[] = {
|
|
{ .compatible = "brcm,bcm2835-spi", },
|
|
{}
|
|
};
|
|
MODULE_DEVICE_TABLE(of, bcm2835_spi_match);
|
|
|
|
static struct platform_driver bcm2835_spi_driver = {
|
|
.driver = {
|
|
.name = DRV_NAME,
|
|
.of_match_table = bcm2835_spi_match,
|
|
},
|
|
.probe = bcm2835_spi_probe,
|
|
.remove = bcm2835_spi_remove,
|
|
.shutdown = bcm2835_spi_shutdown,
|
|
};
|
|
module_platform_driver(bcm2835_spi_driver);
|
|
|
|
MODULE_DESCRIPTION("SPI controller driver for Broadcom BCM2835");
|
|
MODULE_AUTHOR("Chris Boot <bootc@bootc.net>");
|
|
MODULE_LICENSE("GPL");
|