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Blackfin SPI Driver: Add GPIO controlled SPI Slave Select support

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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>
This commit is contained in:
Michael Hennerich 2009-04-06 19:00:51 -07:00 committed by Linus Torvalds
parent e7d02e3c95
commit 42c78b2bf5
2 changed files with 33 additions and 8 deletions
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1
arch/blackfin/include/asm/bfin5xx_spi.h
View file

@ -124,6 +124,7 @@ struct bfin5xx_spi_chip {
u8 bits_per_word;
u8 cs_change_per_word;
u16 cs_chg_udelay; /* Some devices require 16-bit delays */
u32 cs_gpio;
};
#endif /* _SPI_CHANNEL_H_ */

40
drivers/spi/spi_bfin5xx.c
View file

@ -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);
}