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authorMichael Hennerich <michael.hennerich@analog.com>2009-04-06 19:00:51 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-07 08:31:06 -0700
commit42c78b2bf51bafb4cfa98dfecc28dd9b8bcd04b0 (patch)
tree12960b010ec28ff6e5cfeb4a640681464781f51e /drivers/spi
parente7d02e3c9577f070bc77354763bed7f24713dc53 (diff)
Blackfin SPI Driver: Add GPIO controlled SPI Slave Select support
Add support for GPIO controlled SPI Chip Selects. To make use of this feature, set chip_select = 0 and add a proper cs_gpio to your controller_data. struct spi_board_info .chip_select = 0 struct bfin5xx_spi_chip .cs_gpio = GPIO_P### There are various SPI devices that require SPI MODE_0, and need to have the Chip Selects asserted during the entire transfer. Consider using SPI_MODE_3 (SPI_CPHA | SPI_CPOL) if your device allows it. Signed-off-by: Michael Hennerich <michael.hennerich@analog.com> Signed-off-by: Bryan Wu <cooloney@kernel.org> Cc: David Brownell <david-b@pacbell.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/spi')
-rw-r--r--drivers/spi/spi_bfin5xx.c40
1 files changed, 32 insertions, 8 deletions
diff --git a/drivers/spi/spi_bfin5xx.c b/drivers/spi/spi_bfin5xx.c
index 53819c961a3..6aa084e445e 100644
--- a/drivers/spi/spi_bfin5xx.c
+++ b/drivers/spi/spi_bfin5xx.c
@@ -111,6 +111,7 @@ struct chip_data {
u8 bits_per_word; /* 8 or 16 */
u8 cs_change_per_word;
u16 cs_chg_udelay; /* Some devices require > 255usec delay */
+ u32 cs_gpio;
void (*write) (struct driver_data *);
void (*read) (struct driver_data *);
void (*duplex) (struct driver_data *);
@@ -177,22 +178,30 @@ static int bfin_spi_flush(struct driver_data *drv_data)
/* Chip select operation functions for cs_change flag */
static void bfin_spi_cs_active(struct driver_data *drv_data, struct chip_data *chip)
{
- u16 flag = read_FLAG(drv_data);
+ if (likely(chip->chip_select_num)) {
+ u16 flag = read_FLAG(drv_data);
- flag |= chip->flag;
- flag &= ~(chip->flag << 8);
+ flag |= chip->flag;
+ flag &= ~(chip->flag << 8);
- write_FLAG(drv_data, flag);
+ write_FLAG(drv_data, flag);
+ } else {
+ gpio_set_value(chip->cs_gpio, 0);
+ }
}
static void bfin_spi_cs_deactive(struct driver_data *drv_data, struct chip_data *chip)
{
- u16 flag = read_FLAG(drv_data);
+ if (likely(chip->chip_select_num)) {
+ u16 flag = read_FLAG(drv_data);
- flag &= ~chip->flag;
- flag |= (chip->flag << 8);
+ flag &= ~chip->flag;
+ flag |= (chip->flag << 8);
- write_FLAG(drv_data, flag);
+ write_FLAG(drv_data, flag);
+ } else {
+ gpio_set_value(chip->cs_gpio, 1);
+ }
/* Move delay here for consistency */
if (chip->cs_chg_udelay)
@@ -1036,6 +1045,7 @@ static int bfin_spi_setup(struct spi_device *spi)
struct bfin5xx_spi_chip *chip_info = NULL;
struct chip_data *chip;
struct driver_data *drv_data = spi_master_get_devdata(spi->master);
+ int ret;
/* Abort device setup if requested features are not supported */
if (spi->mode & ~(SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST)) {
@@ -1081,6 +1091,7 @@ static int bfin_spi_setup(struct spi_device *spi)
chip->bits_per_word = chip_info->bits_per_word;
chip->cs_change_per_word = chip_info->cs_change_per_word;
chip->cs_chg_udelay = chip_info->cs_chg_udelay;
+ chip->cs_gpio = chip_info->cs_gpio;
}
/* translate common spi framework into our register */
@@ -1121,6 +1132,16 @@ static int bfin_spi_setup(struct spi_device *spi)
chip->flag = 1 << (spi->chip_select);
chip->chip_select_num = spi->chip_select;
+ if (chip->chip_select_num == 0) {
+ ret = gpio_request(chip->cs_gpio, spi->modalias);
+ if (ret) {
+ if (drv_data->dma_requested)
+ free_dma(drv_data->dma_channel);
+ return ret;
+ }
+ gpio_direction_output(chip->cs_gpio, 1);
+ }
+
switch (chip->bits_per_word) {
case 8:
chip->n_bytes = 1;
@@ -1186,6 +1207,9 @@ static void bfin_spi_cleanup(struct spi_device *spi)
peripheral_free(ssel[spi->master->bus_num]
[chip->chip_select_num-1]);
+ if (chip->chip_select_num == 0)
+ gpio_free(chip->cs_gpio);
+
kfree(chip);
}