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spi: bitbang: switch to the generic implementation of transfer_one_message 

Change the bitbang driver to use the generic implementation of
transfer_one_message. This simplifies the bitbang driver code and
provides benefits like the statistics in the generic implementation.

Successfully tested on a IMX6-based system (spi-imx) and on a MIPS-based
router (OpenWRT with spi-ath79).

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Heiner Kallweit 2015-09-29 23:15:53 +02:00 committed by Mark Brown
parent e30d8f2392
commit 0037686596
1 changed files with 36 additions and 89 deletions
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125
drivers/spi/spi-bitbang.c
View File

@ -24,6 +24,8 @@
#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
#define SPI_BITBANG_CS_DELAY 100
/*----------------------------------------------------------------------*/
@ -265,100 +267,28 @@ static int spi_bitbang_prepare_hardware(struct spi_master *spi)
}
static int spi_bitbang_transfer_one(struct spi_master *master,
struct spi_message *m)
struct spi_device *spi,
struct spi_transfer *transfer)
{
struct spi_bitbang *bitbang;
unsigned nsecs;
struct spi_transfer *t = NULL;
unsigned cs_change;
int status;
struct spi_device *spi = m->spi;
struct spi_bitbang *bitbang = spi_master_get_devdata(master);
int status = 0;
bitbang = spi_master_get_devdata(master);
if (bitbang->setup_transfer) {
status = bitbang->setup_transfer(spi, transfer);
if (status < 0)
goto out;
}
/* FIXME this is made-up ... the correct value is known to
* word-at-a-time bitbang code, and presumably chipselect()
* should enforce these requirements too?
*/
nsecs = 100;
if (transfer->len)
status = bitbang->txrx_bufs(spi, transfer);
cs_change = 1;
status = 0;
list_for_each_entry(t, &m->transfers, transfer_list) {
if (bitbang->setup_transfer) {
status = bitbang->setup_transfer(spi, t);
if (status < 0)
break;
}
/* set up default clock polarity, and activate chip;
* this implicitly updates clock and spi modes as
* previously recorded for this device via setup().
* (and also deselects any other chip that might be
* selected ...)
*/
if (cs_change) {
bitbang->chipselect(spi, BITBANG_CS_ACTIVE);
ndelay(nsecs);
}
cs_change = t->cs_change;
if (!t->tx_buf && !t->rx_buf && t->len) {
status = -EINVAL;
break;
}
/* transfer data. the lower level code handles any
* new dma mappings it needs. our caller always gave
* us dma-safe buffers.
*/
if (t->len) {
/* REVISIT dma API still needs a designated
* DMA_ADDR_INVALID; ~0 might be better.
*/
if (!m->is_dma_mapped)
t->rx_dma = t->tx_dma = 0;
status = bitbang->txrx_bufs(spi, t);
}
if (status > 0)
m->actual_length += status;
if (status != t->len) {
/* always report some kind of error */
if (status >= 0)
status = -EREMOTEIO;
break;
}
if (status == transfer->len)
status = 0;
else if (status >= 0)
status = -EREMOTEIO;
/* protocol tweaks before next transfer */
if (t->delay_usecs)
udelay(t->delay_usecs);
if (cs_change &&
!list_is_last(&t->transfer_list, &m->transfers)) {
/* sometimes a short mid-message deselect of the chip
* may be needed to terminate a mode or command
*/
ndelay(nsecs);
bitbang->chipselect(spi, BITBANG_CS_INACTIVE);
ndelay(nsecs);
}
}
m->status = status;
/* normally deactivate chipselect ... unless no error and
* cs_change has hinted that the next message will probably
* be for this chip too.
*/
if (!(status == 0 && cs_change)) {
ndelay(nsecs);
bitbang->chipselect(spi, BITBANG_CS_INACTIVE);
ndelay(nsecs);
}
spi_finalize_current_message(master);
out:
spi_finalize_current_transfer(master);
return status;
}
@ -376,6 +306,22 @@ static int spi_bitbang_unprepare_hardware(struct spi_master *spi)
return 0;
}
static void spi_bitbang_set_cs(struct spi_device *spi, bool enable)
{
struct spi_bitbang *bitbang = spi_master_get_devdata(spi->master);
/* SPI core provides CS high / low, but bitbang driver
* expects CS active
* spi device driver takes care of handling SPI_CS_HIGH
*/
enable = (!!(spi->mode & SPI_CS_HIGH) == enable);
ndelay(SPI_BITBANG_CS_DELAY);
bitbang->chipselect(spi, enable ? BITBANG_CS_ACTIVE :
BITBANG_CS_INACTIVE);
ndelay(SPI_BITBANG_CS_DELAY);
}
/*----------------------------------------------------------------------*/
/**
@ -424,7 +370,8 @@ int spi_bitbang_start(struct spi_bitbang *bitbang)
master->prepare_transfer_hardware = spi_bitbang_prepare_hardware;
master->unprepare_transfer_hardware = spi_bitbang_unprepare_hardware;
master->transfer_one_message = spi_bitbang_transfer_one;
master->transfer_one = spi_bitbang_transfer_one;
master->set_cs = spi_bitbang_set_cs;
if (!bitbang->txrx_bufs) {
bitbang->use_dma = 0;