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![Gabriel Somlo](/assets/img/avatar_default.png)
Since upstream LiteX recommends that Linux support be limited to designs configured with 32-bit CSR subregisters (see commit a2b71fde in upstream LiteX, https://github.com/enjoy-digital/litex), remove the option to select 8-bit subregisters, significantly reducing the complexity of LiteX CSR (MMIO register) accessor methods. NOTE: for details on the underlying mechanics of LiteX CSR registers, see https://github.com/enjoy-digital/litex/wiki/CSR-Bus or the original LiteX accessors (litex/soc/software/include/hw/common.h in the upstream repository). Signed-off-by: Gabriel Somlo <gsomlo@gmail.com> Cc: Stafford Horne <shorne@gmail.com> Cc: Florent Kermarrec <florent@enjoy-digital.fr> Cc: Mateusz Holenko <mholenko@antmicro.com> Cc: Joel Stanley <joel@jms.id.au> Reviewed-by: Joel Stanley <joel@jms.id.au> Signed-off-by: Stafford Horne <shorne@gmail.com>
143 lines
3.8 KiB
C
143 lines
3.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* LiteX SoC Controller Driver
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*
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* Copyright (C) 2020 Antmicro <www.antmicro.com>
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*
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*/
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#include <linux/litex.h>
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#include <linux/device.h>
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#include <linux/errno.h>
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#include <linux/of.h>
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#include <linux/platform_device.h>
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#include <linux/printk.h>
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#include <linux/module.h>
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#include <linux/io.h>
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#include <linux/reboot.h>
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/* reset register located at the base address */
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#define RESET_REG_OFF 0x00
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#define RESET_REG_VALUE 0x00000001
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#define SCRATCH_REG_OFF 0x04
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#define SCRATCH_REG_VALUE 0x12345678
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#define SCRATCH_TEST_VALUE 0xdeadbeef
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/*
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* Check LiteX CSR read/write access
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*
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* This function reads and writes a scratch register in order to verify if CSR
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* access works.
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*
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* In case any problems are detected, the driver should panic.
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*
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* Access to the LiteX CSR is, by design, done in CPU native endianness.
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* The driver should not dynamically configure access functions when
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* the endianness mismatch is detected. Such situation indicates problems in
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* the soft SoC design and should be solved at the LiteX generator level,
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* not in the software.
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*/
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static int litex_check_csr_access(void __iomem *reg_addr)
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{
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unsigned long reg;
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reg = litex_read32(reg_addr + SCRATCH_REG_OFF);
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if (reg != SCRATCH_REG_VALUE) {
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panic("Scratch register read error - the system is probably broken! Expected: 0x%x but got: 0x%lx",
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SCRATCH_REG_VALUE, reg);
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return -EINVAL;
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}
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litex_write32(reg_addr + SCRATCH_REG_OFF, SCRATCH_TEST_VALUE);
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reg = litex_read32(reg_addr + SCRATCH_REG_OFF);
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if (reg != SCRATCH_TEST_VALUE) {
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panic("Scratch register write error - the system is probably broken! Expected: 0x%x but got: 0x%lx",
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SCRATCH_TEST_VALUE, reg);
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return -EINVAL;
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}
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/* restore original value of the SCRATCH register */
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litex_write32(reg_addr + SCRATCH_REG_OFF, SCRATCH_REG_VALUE);
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pr_info("LiteX SoC Controller driver initialized");
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return 0;
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}
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struct litex_soc_ctrl_device {
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void __iomem *base;
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struct notifier_block reset_nb;
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};
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static int litex_reset_handler(struct notifier_block *this, unsigned long mode,
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void *cmd)
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{
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struct litex_soc_ctrl_device *soc_ctrl_dev =
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container_of(this, struct litex_soc_ctrl_device, reset_nb);
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litex_write32(soc_ctrl_dev->base + RESET_REG_OFF, RESET_REG_VALUE);
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return NOTIFY_DONE;
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}
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#ifdef CONFIG_OF
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static const struct of_device_id litex_soc_ctrl_of_match[] = {
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{.compatible = "litex,soc-controller"},
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{},
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};
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MODULE_DEVICE_TABLE(of, litex_soc_ctrl_of_match);
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#endif /* CONFIG_OF */
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static int litex_soc_ctrl_probe(struct platform_device *pdev)
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{
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struct litex_soc_ctrl_device *soc_ctrl_dev;
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int error;
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soc_ctrl_dev = devm_kzalloc(&pdev->dev, sizeof(*soc_ctrl_dev), GFP_KERNEL);
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if (!soc_ctrl_dev)
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return -ENOMEM;
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soc_ctrl_dev->base = devm_platform_ioremap_resource(pdev, 0);
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if (IS_ERR(soc_ctrl_dev->base))
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return PTR_ERR(soc_ctrl_dev->base);
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error = litex_check_csr_access(soc_ctrl_dev->base);
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if (error)
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return error;
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platform_set_drvdata(pdev, soc_ctrl_dev);
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soc_ctrl_dev->reset_nb.notifier_call = litex_reset_handler;
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soc_ctrl_dev->reset_nb.priority = 128;
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error = register_restart_handler(&soc_ctrl_dev->reset_nb);
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if (error) {
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dev_warn(&pdev->dev, "cannot register restart handler: %d\n",
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error);
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}
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return 0;
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}
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static int litex_soc_ctrl_remove(struct platform_device *pdev)
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{
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struct litex_soc_ctrl_device *soc_ctrl_dev = platform_get_drvdata(pdev);
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unregister_restart_handler(&soc_ctrl_dev->reset_nb);
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return 0;
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}
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static struct platform_driver litex_soc_ctrl_driver = {
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.driver = {
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.name = "litex-soc-controller",
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.of_match_table = of_match_ptr(litex_soc_ctrl_of_match)
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},
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.probe = litex_soc_ctrl_probe,
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.remove = litex_soc_ctrl_remove,
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};
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module_platform_driver(litex_soc_ctrl_driver);
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MODULE_DESCRIPTION("LiteX SoC Controller driver");
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MODULE_AUTHOR("Antmicro <www.antmicro.com>");
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MODULE_LICENSE("GPL v2");
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