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Merge remote-tracking branches 'spi/topic/atmel', 'spi/topic/bcm2385', 'spi/topic/bcm2835', 'spi/topic/bcm53xx' and 'spi/topic/bitbang' into spi-next

hifive-unleashed-5.1
Mark Brown 2015-04-11 23:09:03 +01:00
parent 19655dd083 ea467326e3 b716c4ffc6 704f32d48a b3e7766bc4 232a5adc51
commit f9de73426c
6 changed files with 299 additions and 161 deletions
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8
drivers/spi/spi-atmel.c
View File

@ -180,11 +180,17 @@
| SPI_BF(name, value))
/* Register access macros */
#ifdef CONFIG_AVR32
#define spi_readl(port, reg) \
__raw_readl((port)->regs + SPI_##reg)
#define spi_writel(port, reg, value) \
__raw_writel((value), (port)->regs + SPI_##reg)
#else
#define spi_readl(port, reg) \
readl_relaxed((port)->regs + SPI_##reg)
#define spi_writel(port, reg, value) \
writel_relaxed((value), (port)->regs + SPI_##reg)
#endif
/* use PIO for small transfers, avoiding DMA setup/teardown overhead and
* cache operations; better heuristics consider wordsize and bitrate.
*/

423
drivers/spi/spi-bcm2835.c
View File

@ -3,6 +3,7 @@
*
* Copyright (C) 2012 Chris Boot
* Copyright (C) 2013 Stephen Warren
* Copyright (C) 2015 Martin Sperl
*
* This driver is inspired by:
* spi-ath79.c, Copyright (C) 2009-2011 Gabor Juhos <juhosg@openwrt.org>
@ -29,6 +30,7 @@
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/of_gpio.h>
#include <linux/of_device.h>
#include <linux/spi/spi.h>
@ -66,8 +68,10 @@
#define BCM2835_SPI_CS_CS_10 0x00000002
#define BCM2835_SPI_CS_CS_01 0x00000001
#define BCM2835_SPI_TIMEOUT_MS 30000
#define BCM2835_SPI_MODE_BITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_NO_CS)
#define BCM2835_SPI_POLLING_LIMIT_US 30
#define BCM2835_SPI_TIMEOUT_MS 30000
#define BCM2835_SPI_MODE_BITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH \
| SPI_NO_CS | SPI_3WIRE)
#define DRV_NAME "spi-bcm2835"
@ -75,10 +79,10 @@ struct bcm2835_spi {
void __iomem *regs;
struct clk *clk;
int irq;
struct completion done;
const u8 *tx_buf;
u8 *rx_buf;
int len;
int tx_len;
int rx_len;
};
static inline u32 bcm2835_rd(struct bcm2835_spi *bs, unsigned reg)
@ -91,205 +95,315 @@ static inline void bcm2835_wr(struct bcm2835_spi *bs, unsigned reg, u32 val)
writel(val, bs->regs + reg);
}
static inline void bcm2835_rd_fifo(struct bcm2835_spi *bs, int len)
static inline void bcm2835_rd_fifo(struct bcm2835_spi *bs)
{
u8 byte;
while (len--) {
while ((bs->rx_len) &&
(bcm2835_rd(bs, BCM2835_SPI_CS) & BCM2835_SPI_CS_RXD)) {
byte = bcm2835_rd(bs, BCM2835_SPI_FIFO);
if (bs->rx_buf)
*bs->rx_buf++ = byte;
bs->rx_len--;
}
}
static inline void bcm2835_wr_fifo(struct bcm2835_spi *bs, int len)
static inline void bcm2835_wr_fifo(struct bcm2835_spi *bs)
{
u8 byte;
if (len > bs->len)
len = bs->len;
while (len--) {
while ((bs->tx_len) &&
(bcm2835_rd(bs, BCM2835_SPI_CS) & BCM2835_SPI_CS_TXD)) {
byte = bs->tx_buf ? *bs->tx_buf++ : 0;
bcm2835_wr(bs, BCM2835_SPI_FIFO, byte);
bs->len--;
bs->tx_len--;
}
}
static void bcm2835_spi_reset_hw(struct spi_master *master)
{
struct bcm2835_spi *bs = spi_master_get_devdata(master);
u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
/* Disable SPI interrupts and transfer */
cs &= ~(BCM2835_SPI_CS_INTR |
BCM2835_SPI_CS_INTD |
BCM2835_SPI_CS_TA);
/* and reset RX/TX FIFOS */
cs |= BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX;
/* and reset the SPI_HW */
bcm2835_wr(bs, BCM2835_SPI_CS, cs);
}
static irqreturn_t bcm2835_spi_interrupt(int irq, void *dev_id)
{
struct spi_master *master = dev_id;
struct bcm2835_spi *bs = spi_master_get_devdata(master);
u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
/*
* RXR - RX needs Reading. This means 12 (or more) bytes have been
* transmitted and hence 12 (or more) bytes have been received.
*
* The FIFO is 16-bytes deep. We check for this interrupt to keep the
* FIFO full; we have a 4-byte-time buffer for IRQ latency. We check
* this before DONE (TX empty) just in case we delayed processing this
* interrupt for some reason.
*
* We only check for this case if we have more bytes to TX; at the end
* of the transfer, we ignore this pipelining optimization, and let
* bcm2835_spi_finish_transfer() drain the RX FIFO.
*/
if (bs->len && (cs & BCM2835_SPI_CS_RXR)) {
/* Read 12 bytes of data */
bcm2835_rd_fifo(bs, 12);
/* Read as many bytes as possible from FIFO */
bcm2835_rd_fifo(bs);
/* Write as many bytes as possible to FIFO */
bcm2835_wr_fifo(bs);
/* Write up to 12 bytes */
bcm2835_wr_fifo(bs, 12);
/*
* We must have written something to the TX FIFO due to the
* bs->len check above, so cannot be DONE. Hence, return
* early. Note that DONE could also be set if we serviced an
* RXR interrupt really late.
*/
return IRQ_HANDLED;
/* based on flags decide if we can finish the transfer */
if (bcm2835_rd(bs, BCM2835_SPI_CS) & BCM2835_SPI_CS_DONE) {
/* Transfer complete - reset SPI HW */
bcm2835_spi_reset_hw(master);
/* wake up the framework */
complete(&master->xfer_completion);
}
/*
* DONE - TX empty. This occurs when we first enable the transfer
* since we do not pre-fill the TX FIFO. At any other time, given that
* we refill the TX FIFO above based on RXR, and hence ignore DONE if
* RXR is set, DONE really does mean end-of-transfer.
*/
if (cs & BCM2835_SPI_CS_DONE) {
if (bs->len) { /* First interrupt in a transfer */
bcm2835_wr_fifo(bs, 16);
} else { /* Transfer complete */
/* Disable SPI interrupts */
cs &= ~(BCM2835_SPI_CS_INTR | BCM2835_SPI_CS_INTD);
bcm2835_wr(bs, BCM2835_SPI_CS, cs);
/*
* Wake up bcm2835_spi_transfer_one(), which will call
* bcm2835_spi_finish_transfer(), to drain the RX FIFO.
*/
complete(&bs->done);
}
return IRQ_HANDLED;
}
return IRQ_NONE;
return IRQ_HANDLED;
}
static int bcm2835_spi_start_transfer(struct spi_device *spi,
struct spi_transfer *tfr)
static int bcm2835_spi_transfer_one_poll(struct spi_master *master,
struct spi_device *spi,
struct spi_transfer *tfr,
u32 cs,
unsigned long xfer_time_us)
{
struct bcm2835_spi *bs = spi_master_get_devdata(spi->master);
unsigned long spi_hz, clk_hz, cdiv;
u32 cs = BCM2835_SPI_CS_INTR | BCM2835_SPI_CS_INTD | BCM2835_SPI_CS_TA;
struct bcm2835_spi *bs = spi_master_get_devdata(master);
unsigned long timeout = jiffies +
max(4 * xfer_time_us * HZ / 1000000, 2uL);
spi_hz = tfr->speed_hz;
clk_hz = clk_get_rate(bs->clk);
/* enable HW block without interrupts */
bcm2835_wr(bs, BCM2835_SPI_CS, cs | BCM2835_SPI_CS_TA);
if (spi_hz >= clk_hz / 2) {
cdiv = 2; /* clk_hz/2 is the fastest we can go */
} else if (spi_hz) {
/* CDIV must be a power of two */
cdiv = roundup_pow_of_two(DIV_ROUND_UP(clk_hz, spi_hz));
if (cdiv >= 65536)
cdiv = 0; /* 0 is the slowest we can go */
} else
cdiv = 0; /* 0 is the slowest we can go */
if (spi->mode & SPI_CPOL)
cs |= BCM2835_SPI_CS_CPOL;
if (spi->mode & SPI_CPHA)
cs |= BCM2835_SPI_CS_CPHA;
if (!(spi->mode & SPI_NO_CS)) {
if (spi->mode & SPI_CS_HIGH) {
cs |= BCM2835_SPI_CS_CSPOL;
cs |= BCM2835_SPI_CS_CSPOL0 << spi->chip_select;
/* set timeout to 4x the expected time, or 2 jiffies */
/* loop until finished the transfer */
while (bs->rx_len) {
/* read from fifo as much as possible */
bcm2835_rd_fifo(bs);
/* fill in tx fifo as much as possible */
bcm2835_wr_fifo(bs);
/* if we still expect some data after the read,
* check for a possible timeout
*/
if (bs->rx_len && time_after(jiffies, timeout)) {
/* Transfer complete - reset SPI HW */
bcm2835_spi_reset_hw(master);
/* and return timeout */
return -ETIMEDOUT;
}
cs |= spi->chip_select;
}
reinit_completion(&bs->done);
bs->tx_buf = tfr->tx_buf;
bs->rx_buf = tfr->rx_buf;
bs->len = tfr->len;
/* Transfer complete - reset SPI HW */
bcm2835_spi_reset_hw(master);
/* and return without waiting for completion */
return 0;
}
static int bcm2835_spi_transfer_one_irq(struct spi_master *master,
struct spi_device *spi,
struct spi_transfer *tfr,
u32 cs)
{
struct bcm2835_spi *bs = spi_master_get_devdata(master);
/* fill in fifo if we have gpio-cs
* note that there have been rare events where the native-CS
* flapped for <1us which may change the behaviour
* with gpio-cs this does not happen, so it is implemented
* only for this case
*/
if (gpio_is_valid(spi->cs_gpio)) {
/* enable HW block, but without interrupts enabled
* this would triggern an immediate interrupt
*/
bcm2835_wr(bs, BCM2835_SPI_CS,
cs | BCM2835_SPI_CS_TA);
/* fill in tx fifo as much as possible */
bcm2835_wr_fifo(bs);
}
bcm2835_wr(bs, BCM2835_SPI_CLK, cdiv);
/*
* Enable the HW block. This will immediately trigger a DONE (TX
* empty) interrupt, upon which we will fill the TX FIFO with the
* first TX bytes. Pre-filling the TX FIFO here to avoid the
* interrupt doesn't work:-(
*/
cs |= BCM2835_SPI_CS_INTR | BCM2835_SPI_CS_INTD | BCM2835_SPI_CS_TA;
bcm2835_wr(bs, BCM2835_SPI_CS, cs);
return 0;
}
static int bcm2835_spi_finish_transfer(struct spi_device *spi,
struct spi_transfer *tfr, bool cs_change)
{
struct bcm2835_spi *bs = spi_master_get_devdata(spi->master);
u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
/* Drain RX FIFO */
while (cs & BCM2835_SPI_CS_RXD) {
bcm2835_rd_fifo(bs, 1);
cs = bcm2835_rd(bs, BCM2835_SPI_CS);
}
if (tfr->delay_usecs)
udelay(tfr->delay_usecs);
if (cs_change)
/* Clear TA flag */
bcm2835_wr(bs, BCM2835_SPI_CS, cs & ~BCM2835_SPI_CS_TA);
return 0;
/* signal that we need to wait for completion */
return 1;
}
static int bcm2835_spi_transfer_one(struct spi_master *master,
struct spi_message *mesg)
struct spi_device *spi,
struct spi_transfer *tfr)
{
struct bcm2835_spi *bs = spi_master_get_devdata(master);
struct spi_transfer *tfr;
struct spi_device *spi = mesg->spi;
int err = 0;
unsigned int timeout;
bool cs_change;
unsigned long spi_hz, clk_hz, cdiv;
unsigned long spi_used_hz, xfer_time_us;
u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
list_for_each_entry(tfr, &mesg->transfers, transfer_list) {
err = bcm2835_spi_start_transfer(spi, tfr);
if (err)
goto out;
/* set clock */
spi_hz = tfr->speed_hz;
clk_hz = clk_get_rate(bs->clk);
timeout = wait_for_completion_timeout(&bs->done,
msecs_to_jiffies(BCM2835_SPI_TIMEOUT_MS));
if (!timeout) {
err = -ETIMEDOUT;
goto out;
}
if (spi_hz >= 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(clk_hz, spi_hz);
cdiv += (cdiv % 2);
cs_change = tfr->cs_change ||
list_is_last(&tfr->transfer_list, &mesg->transfers);
if (cdiv >= 65536)
cdiv = 0; /* 0 is the slowest we can go */
} else {
cdiv = 0; /* 0 is the slowest we can go */
}
spi_used_hz = cdiv ? (clk_hz / cdiv) : (clk_hz / 65536);
bcm2835_wr(bs, BCM2835_SPI_CLK, cdiv);
err = bcm2835_spi_finish_transfer(spi, tfr, cs_change);
if (err)
goto out;
/* handle all the modes */
if ((spi->mode & SPI_3WIRE) && (tfr->rx_buf))
cs |= BCM2835_SPI_CS_REN;
if (spi->mode & SPI_CPOL)
cs |= BCM2835_SPI_CS_CPOL;
if (spi->mode & SPI_CPHA)
cs |= BCM2835_SPI_CS_CPHA;
mesg->actual_length += (tfr->len - bs->len);
/* for gpio_cs set dummy CS so that no HW-CS get changed
* we can not run this in bcm2835_spi_set_cs, as it does
* not get called for cs_gpio cases, so we need to do it here
*/
if (gpio_is_valid(spi->cs_gpio) || (spi->mode & SPI_NO_CS))
cs |= BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01;
/* 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 */
xfer_time_us = tfr->len
* 9 /* clocks/byte - SPI-HW waits 1 clock after each byte */
* 1000000 / spi_used_hz;
/* for short requests run polling*/
if (xfer_time_us <= BCM2835_SPI_POLLING_LIMIT_US)
return bcm2835_spi_transfer_one_poll(master, spi, tfr,
cs, xfer_time_us);
return bcm2835_spi_transfer_one_irq(master, spi, tfr, cs);
}
static void bcm2835_spi_handle_err(struct spi_master *master,
struct spi_message *msg)
{
bcm2835_spi_reset_hw(master);
}
static void bcm2835_spi_set_cs(struct spi_device *spi, bool gpio_level)
{
/*
* we can assume that we are "native" as per spi_set_cs
* calling us ONLY when cs_gpio is not set
* we can also assume that we are CS < 3 as per bcm2835_spi_setup
* we would not get called because of error handling there.
* the level passed is the electrical level not enabled/disabled
* so it has to get translated back to enable/disable
* see spi_set_cs in spi.c for the implementation
*/
struct spi_master *master = spi->master;
struct bcm2835_spi *bs = spi_master_get_devdata(master);
u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
bool enable;
/* calculate the enable flag from the passed gpio_level */
enable = (spi->mode & SPI_CS_HIGH) ? gpio_level : !gpio_level;
/* set flags for "reverse" polarity in the registers */
if (spi->mode & SPI_CS_HIGH) {
/* set the correct CS-bits */
cs |= BCM2835_SPI_CS_CSPOL;
cs |= BCM2835_SPI_CS_CSPOL0 << spi->chip_select;
} else {
/* clean the CS-bits */
cs &= ~BCM2835_SPI_CS_CSPOL;
cs &= ~(BCM2835_SPI_CS_CSPOL0 << spi->chip_select);
}
out:
/* Clear FIFOs, and disable the HW block */
bcm2835_wr(bs, BCM2835_SPI_CS,
BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX);
mesg->status = err;
spi_finalize_current_message(master);
/* select the correct chip_select depending on disabled/enabled */
if (enable) {
/* set cs correctly */
if (spi->mode & SPI_NO_CS) {
/* use the "undefined" chip-select */
cs |= BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01;
} else {
/* set the chip select */
cs &= ~(BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01);
cs |= spi->chip_select;
}
} else {
/* disable CSPOL which puts HW-CS into deselected state */
cs &= ~BCM2835_SPI_CS_CSPOL;
/* use the "undefined" chip-select as precaution */
cs |= BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01;
}
/* finally set the calculated flags in SPI_CS */
bcm2835_wr(bs, BCM2835_SPI_CS, cs);
}
static int chip_match_name(struct gpio_chip *chip, void *data)
{
return !strcmp(chip->label, data);
}
static int bcm2835_spi_setup(struct spi_device *spi)
{
int err;
struct gpio_chip *chip;
/*
* sanity checking the native-chipselects
*/
if (spi->mode & SPI_NO_CS)
return 0;
if (gpio_is_valid(spi->cs_gpio))
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");
return -EINVAL;
}
/* now translate native cs to GPIO */
/* get the gpio chip for the base */
chip = gpiochip_find("pinctrl-bcm2835", chip_match_name);
if (!chip)
return 0;
/* and calculate the real CS */
spi->cs_gpio = chip->base + 8 - spi->chip_select;
/* and set up the "mode" and level */
dev_info(&spi->dev, "setting up native-CS%i as GPIO %i\n",
spi->chip_select, spi->cs_gpio);
/* set up GPIO as output and pull to the correct level */
err = gpio_direction_output(spi->cs_gpio,
(spi->mode & SPI_CS_HIGH) ? 0 : 1);
if (err) {
dev_err(&spi->dev,
"could not set CS%i gpio %i as output: %i",
spi->chip_select, spi->cs_gpio, err);
return err;
}
/* the implementation of pinctrl-bcm2835 currently does not
* set the GPIO value when using gpio_direction_output
* so we are setting it here explicitly
*/
gpio_set_value(spi->cs_gpio, (spi->mode & SPI_CS_HIGH) ? 0 : 1);
return 0;
}
@ -312,13 +426,14 @@ static int bcm2835_spi_probe(struct platform_device *pdev)
master->mode_bits = BCM2835_SPI_MODE_BITS;
master->bits_per_word_mask = SPI_BPW_MASK(8);
master->num_chipselect = 3;
master->transfer_one_message = bcm2835_spi_transfer_one;
master->setup = bcm2835_spi_setup;
master->set_cs = bcm2835_spi_set_cs;
master->transfer_one = bcm2835_spi_transfer_one;
master->handle_err = bcm2835_spi_handle_err;
master->dev.of_node = pdev->dev.of_node;
bs = spi_master_get_devdata(master);
init_completion(&bs->done);
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
bs->regs = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(bs->regs)) {
@ -343,13 +458,13 @@ static int bcm2835_spi_probe(struct platform_device *pdev)
clk_prepare_enable(bs->clk);
err = devm_request_irq(&pdev->dev, bs->irq, bcm2835_spi_interrupt, 0,
dev_name(&pdev->dev), master);
dev_name(&pdev->dev), master);
if (err) {
dev_err(&pdev->dev, "could not request IRQ: %d\n", err);
goto out_clk_disable;
}
/* initialise the hardware */
/* initialise the hardware with the default polarities */
bcm2835_wr(bs, BCM2835_SPI_CS,
BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX);

4
drivers/spi/spi-bcm53xx.c
View File

@ -44,7 +44,7 @@ static int bcm53xxspi_wait(struct bcm53xxspi *b53spi, unsigned int timeout_ms)
u32 tmp;
/* SPE bit has to be 0 before we read MSPI STATUS */
deadline = jiffies + BCM53XXSPI_SPE_TIMEOUT_MS * HZ / 1000;
deadline = jiffies + msecs_to_jiffies(BCM53XXSPI_SPE_TIMEOUT_MS);
do {
tmp = bcm53xxspi_read(b53spi, B53SPI_MSPI_SPCR2);
if (!(tmp & B53SPI_MSPI_SPCR2_SPE))
@ -56,7 +56,7 @@ static int bcm53xxspi_wait(struct bcm53xxspi *b53spi, unsigned int timeout_ms)
goto spi_timeout;
/* Check status */
deadline = jiffies + timeout_ms * HZ / 1000;
deadline = jiffies + msecs_to_jiffies(timeout_ms);
do {
tmp = bcm53xxspi_read(b53spi, B53SPI_MSPI_MSPI_STATUS);
if (tmp & B53SPI_MSPI_MSPI_STATUS_SPIF) {

18
drivers/spi/spi-bitbang-txrx.h
View File

@ -49,12 +49,17 @@ bitbang_txrx_be_cpha0(struct spi_device *spi,
{
/* if (cpol == 0) this is SPI_MODE_0; else this is SPI_MODE_2 */
bool oldbit = !(word & 1);
/* clock starts at inactive polarity */
for (word <<= (32 - bits); likely(bits); bits--) {
/* setup MSB (to slave) on trailing edge */
if ((flags & SPI_MASTER_NO_TX) == 0)
setmosi(spi, word & (1 << 31));
if ((flags & SPI_MASTER_NO_TX) == 0) {
if ((word & (1 << 31)) != oldbit) {
setmosi(spi, word & (1 << 31));
oldbit = word & (1 << 31);
}
}
spidelay(nsecs); /* T(setup) */
setsck(spi, !cpol);
@ -76,13 +81,18 @@ bitbang_txrx_be_cpha1(struct spi_device *spi,
{
/* if (cpol == 0) this is SPI_MODE_1; else this is SPI_MODE_3 */
bool oldbit = !(word & (1 << 31));
/* clock starts at inactive polarity */
for (word <<= (32 - bits); likely(bits); bits--) {
/* setup MSB (to slave) on leading edge */
setsck(spi, !cpol);
if ((flags & SPI_MASTER_NO_TX) == 0)
setmosi(spi, word & (1 << 31));
if ((flags & SPI_MASTER_NO_TX) == 0) {
if ((word & (1 << 31)) != oldbit) {
setmosi(spi, word & (1 << 31));
oldbit = word & (1 << 31);
}
}
spidelay(nsecs); /* T(setup) */
setsck(spi, cpol);

3
drivers/spi/spi.c
View File

@ -850,6 +850,9 @@ out:
if (msg->status == -EINPROGRESS)
msg->status = ret;
if (msg->status)
master->handle_err(master, msg);
spi_finalize_current_message(master);
return ret;

4
include/linux/spi/spi.h
View File

@ -294,6 +294,8 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv)
* transfer_one_message are mutually exclusive; when both
* are set, the generic subsystem does not call your
* transfer_one callback.
* @handle_err: the subsystem calls the driver to handle and error that occurs
* in the generic implementation of transfer_one_message().
* @unprepare_message: undo any work done by prepare_message().
* @cs_gpios: Array of GPIOs to use as chip select lines; one per CS
* number. Any individual value may be -ENOENT for CS lines that
@ -448,6 +450,8 @@ struct spi_master {
void (*set_cs)(struct spi_device *spi, bool enable);
int (*transfer_one)(struct spi_master *master, struct spi_device *spi,
struct spi_transfer *transfer);
void (*handle_err)(struct spi_master *master,
struct spi_message *message);
/* gpio chip select */
int *cs_gpios;