2015-01-23 07:37:45 +00:00
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/*
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* SPI bridge driver for the Greybus "generic" SPI module.
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*
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* Copyright 2014 Google Inc.
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* Copyright 2014 Linaro Ltd.
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*
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* Released under the GPLv2 only.
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*/
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#include <linux/bitops.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/spi/spi.h>
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#include "greybus.h"
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struct gb_spi {
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struct gb_connection *connection;
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/* Modes supported by spi controller */
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u16 mode;
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/* constraints of the spi controller */
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u16 flags;
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/*
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* copied from kernel:
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*
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* A mask indicating which values of bits_per_word are supported by the
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* controller. Bit n indicates that a bits_per_word n+1 is suported. If
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* set, the SPI core will reject any transfer with an unsupported
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* bits_per_word. If not set, this value is simply ignored, and it's up
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* to the individual driver to perform any validation.
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*/
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u32 bits_per_word_mask;
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/*
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* chipselects will be integral to many controllers; some others might
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* use board-specific GPIOs.
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*/
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u16 num_chipselect;
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};
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/* Routines to transfer data */
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static struct gb_operation *
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gb_spi_operation_create(struct gb_connection *connection,
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struct spi_message *msg, u32 *total_len)
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{
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struct gb_spi_transfer_request *request;
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struct spi_device *dev = msg->spi;
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struct spi_transfer *xfer;
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struct gb_spi_transfer *gb_xfer;
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struct gb_operation *operation;
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u32 tx_size = 0, rx_size = 0, count = 0, request_size;
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void *tx_data;
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/* Find number of transfers queued and tx/rx length in the message */
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list_for_each_entry(xfer, &msg->transfers, transfer_list) {
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if (!xfer->tx_buf && !xfer->rx_buf) {
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2015-03-19 15:46:17 +00:00
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dev_err(&connection->dev,
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"bufferless transfer, length %u\n", xfer->len);
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2015-01-23 07:37:45 +00:00
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return NULL;
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}
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if (xfer->tx_buf)
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tx_size += xfer->len;
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if (xfer->rx_buf)
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rx_size += xfer->len;
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*total_len += xfer->len;
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count++;
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}
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/* Too many transfers ? */
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if (count > (u32)U16_MAX) {
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2015-03-19 15:46:17 +00:00
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dev_err(&connection->dev, "transfer count (%u) too big\n",
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count);
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2015-01-23 07:37:45 +00:00
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return NULL;
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}
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/*
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* In addition to space for all message descriptors we need
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* to have enough to hold all tx data.
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*/
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request_size = sizeof(*request);
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request_size += count * sizeof(*gb_xfer);
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request_size += tx_size;
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/* Response consists only of incoming data */
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operation = gb_operation_create(connection, GB_SPI_TYPE_TRANSFER,
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2015-07-01 10:37:22 +00:00
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request_size, rx_size, GFP_KERNEL);
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2015-01-23 07:37:45 +00:00
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if (!operation)
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return NULL;
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request = operation->request->payload;
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2015-01-27 03:38:04 +00:00
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request->count = cpu_to_le16(count);
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2015-01-23 07:37:45 +00:00
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request->mode = dev->mode;
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request->chip_select = dev->chip_select;
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gb_xfer = &request->transfers[0];
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tx_data = gb_xfer + count; /* place tx data after last gb_xfer */
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/* Fill in the transfers array */
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list_for_each_entry(xfer, &msg->transfers, transfer_list) {
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2015-01-27 03:38:04 +00:00
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gb_xfer->speed_hz = cpu_to_le32(xfer->speed_hz);
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2015-01-23 07:37:45 +00:00
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gb_xfer->len = cpu_to_le32(xfer->len);
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gb_xfer->delay_usecs = cpu_to_le16(xfer->delay_usecs);
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gb_xfer->cs_change = xfer->cs_change;
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gb_xfer->bits_per_word = xfer->bits_per_word;
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gb_xfer++;
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/* Copy tx data */
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if (xfer->tx_buf) {
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memcpy(tx_data, xfer->tx_buf, xfer->len);
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tx_data += xfer->len;
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}
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}
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return operation;
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}
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static void gb_spi_decode_response(struct spi_message *msg,
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struct gb_spi_transfer_response *response)
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{
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struct spi_transfer *xfer;
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void *rx_data = response->data;
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list_for_each_entry(xfer, &msg->transfers, transfer_list) {
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/* Copy rx data */
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if (xfer->rx_buf) {
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memcpy(xfer->rx_buf, rx_data, xfer->len);
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rx_data += xfer->len;
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}
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}
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}
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static int gb_spi_transfer_one_message(struct spi_master *master,
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struct spi_message *msg)
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{
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struct gb_spi *spi = spi_master_get_devdata(master);
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struct gb_connection *connection = spi->connection;
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struct gb_spi_transfer_response *response;
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struct gb_operation *operation;
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u32 len = 0;
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int ret;
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operation = gb_spi_operation_create(connection, msg, &len);
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if (!operation)
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return -ENOMEM;
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ret = gb_operation_request_send_sync(operation);
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if (!ret) {
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response = operation->response->payload;
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if (response)
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gb_spi_decode_response(msg, response);
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} else {
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pr_err("transfer operation failed (%d)\n", ret);
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}
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gb_operation_destroy(operation);
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msg->actual_length = len;
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msg->status = 0;
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spi_finalize_current_message(master);
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return ret;
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}
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static int gb_spi_setup(struct spi_device *spi)
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{
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/* Nothing to do for now */
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return 0;
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}
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static void gb_spi_cleanup(struct spi_device *spi)
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{
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/* Nothing to do for now */
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}
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/* Routines to get controller infomation */
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/*
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* Map Greybus spi mode bits/flags/bpw into Linux ones.
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* All bits are same for now and so these macro's return same values.
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*/
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#define gb_spi_mode_map(mode) mode
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#define gb_spi_flags_map(flags) flags
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static int gb_spi_mode_operation(struct gb_spi *spi)
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{
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struct gb_spi_mode_response response;
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u16 mode;
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int ret;
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ret = gb_operation_sync(spi->connection, GB_SPI_TYPE_MODE,
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NULL, 0, &response, sizeof(response));
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if (ret)
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return ret;
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mode = le16_to_cpu(response.mode);
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spi->mode = gb_spi_mode_map(mode);
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return 0;
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}
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static int gb_spi_flags_operation(struct gb_spi *spi)
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{
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struct gb_spi_flags_response response;
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u16 flags;
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int ret;
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ret = gb_operation_sync(spi->connection, GB_SPI_TYPE_FLAGS,
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NULL, 0, &response, sizeof(response));
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if (ret)
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return ret;
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flags = le16_to_cpu(response.flags);
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spi->flags = gb_spi_flags_map(flags);
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return 0;
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}
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static int gb_spi_bpw_operation(struct gb_spi *spi)
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{
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struct gb_spi_bpw_response response;
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int ret;
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ret = gb_operation_sync(spi->connection, GB_SPI_TYPE_BITS_PER_WORD_MASK,
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NULL, 0, &response, sizeof(response));
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if (ret)
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return ret;
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spi->bits_per_word_mask = le32_to_cpu(response.bits_per_word_mask);
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return 0;
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}
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static int gb_spi_chipselect_operation(struct gb_spi *spi)
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{
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struct gb_spi_chipselect_response response;
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int ret;
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ret = gb_operation_sync(spi->connection, GB_SPI_TYPE_NUM_CHIPSELECT,
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NULL, 0, &response, sizeof(response));
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if (ret)
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return ret;
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2015-01-27 03:38:04 +00:00
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spi->num_chipselect = le16_to_cpu(response.num_chipselect);
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2015-01-23 07:37:45 +00:00
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return 0;
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}
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/*
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* Initialize the spi device. This includes verifying we can support it (based
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* on the protocol version it advertises). If that's OK, we get and cached its
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* mode bits & flags.
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*/
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static int gb_spi_init(struct gb_spi *spi)
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{
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int ret;
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/* mode never changes, just get it once */
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ret = gb_spi_mode_operation(spi);
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if (ret)
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return ret;
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/* flags never changes, just get it once */
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ret = gb_spi_flags_operation(spi);
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if (ret)
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return ret;
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/* total number of chipselects never changes, just get it once */
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ret = gb_spi_chipselect_operation(spi);
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if (ret)
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return ret;
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/* bits-per-word-mask never changes, just get it once */
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return gb_spi_bpw_operation(spi);
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}
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static int gb_spi_connection_init(struct gb_connection *connection)
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{
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struct gb_spi *spi;
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struct spi_master *master;
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int ret;
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/* Allocate master with space for data */
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master = spi_alloc_master(&connection->dev, sizeof(*spi));
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if (!master) {
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2015-03-19 15:46:17 +00:00
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dev_err(&connection->dev, "cannot alloc SPI master\n");
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2015-01-23 07:37:45 +00:00
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return -ENOMEM;
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}
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spi = spi_master_get_devdata(master);
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spi->connection = connection;
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connection->private = master;
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ret = gb_spi_init(spi);
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if (ret)
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goto out_err;
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master->bus_num = 0; /* How do we get controller id here? */
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master->num_chipselect = spi->num_chipselect;
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master->mode_bits = spi->mode;
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master->flags = spi->flags;
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master->bits_per_word_mask = spi->bits_per_word_mask;
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/* Attach methods */
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master->cleanup = gb_spi_cleanup;
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master->setup = gb_spi_setup;
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master->transfer_one_message = gb_spi_transfer_one_message;
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ret = spi_register_master(master);
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if (!ret)
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return 0;
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out_err:
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spi_master_put(master);
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return ret;
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}
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static void gb_spi_connection_exit(struct gb_connection *connection)
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{
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struct spi_master *master = connection->private;
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spi_unregister_master(master);
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}
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static struct gb_protocol spi_protocol = {
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.name = "spi",
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.id = GREYBUS_PROTOCOL_SPI,
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2015-08-08 04:55:38 +00:00
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.major = GB_SPI_VERSION_MAJOR,
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.minor = GB_SPI_VERSION_MINOR,
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2015-01-23 07:37:45 +00:00
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.connection_init = gb_spi_connection_init,
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.connection_exit = gb_spi_connection_exit,
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.request_recv = NULL,
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};
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2015-07-01 06:43:52 +00:00
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gb_builtin_protocol_driver(spi_protocol);
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