From 42c78b2bf51bafb4cfa98dfecc28dd9b8bcd04b0 Mon Sep 17 00:00:00 2001 From: Michael Hennerich Date: Mon, 6 Apr 2009 19:00:51 -0700 Subject: 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 Signed-off-by: Bryan Wu Cc: David Brownell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/spi/spi_bfin5xx.c | 40 ++++++++++++++++++++++++++++++++-------- 1 file changed, 32 insertions(+), 8 deletions(-) (limited to 'drivers/spi') 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); } -- cgit v1.2.3