diff options
author | Michael Hennerich <michael.hennerich@analog.com> | 2009-04-06 19:00:51 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-04-07 08:31:06 -0700 |
commit | 42c78b2bf51bafb4cfa98dfecc28dd9b8bcd04b0 (patch) | |
tree | 12960b010ec28ff6e5cfeb4a640681464781f51e /drivers/spi | |
parent | e7d02e3c9577f070bc77354763bed7f24713dc53 (diff) | |
download | linux-42c78b2bf51bafb4cfa98dfecc28dd9b8bcd04b0.tar.bz2 |
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.c | 40 |
1 files changed, 32 insertions, 8 deletions
diff --git a/drivers/spi/spi_bfin5xx.c b/drivers/spi/spi_bfin5xx.c index 53819c961a31..6aa084e445e6 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); } |