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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>
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e7d02e3c95
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42c78b2bf5
2 changed files with 33 additions and 8 deletions
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@ -124,6 +124,7 @@ struct bfin5xx_spi_chip {
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u8 bits_per_word;
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u8 cs_change_per_word;
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u16 cs_chg_udelay; /* Some devices require 16-bit delays */
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u32 cs_gpio;
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};
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#endif /* _SPI_CHANNEL_H_ */
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@ -111,6 +111,7 @@ struct chip_data {
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u8 bits_per_word; /* 8 or 16 */
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u8 cs_change_per_word;
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u16 cs_chg_udelay; /* Some devices require > 255usec delay */
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u32 cs_gpio;
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void (*write) (struct driver_data *);
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void (*read) (struct driver_data *);
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void (*duplex) (struct driver_data *);
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@ -177,22 +178,30 @@ static int bfin_spi_flush(struct driver_data *drv_data)
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/* Chip select operation functions for cs_change flag */
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static void bfin_spi_cs_active(struct driver_data *drv_data, struct chip_data *chip)
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{
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u16 flag = read_FLAG(drv_data);
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if (likely(chip->chip_select_num)) {
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u16 flag = read_FLAG(drv_data);
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flag |= chip->flag;
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flag &= ~(chip->flag << 8);
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flag |= chip->flag;
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flag &= ~(chip->flag << 8);
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write_FLAG(drv_data, flag);
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write_FLAG(drv_data, flag);
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} else {
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gpio_set_value(chip->cs_gpio, 0);
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}
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}
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static void bfin_spi_cs_deactive(struct driver_data *drv_data, struct chip_data *chip)
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{
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u16 flag = read_FLAG(drv_data);
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if (likely(chip->chip_select_num)) {
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u16 flag = read_FLAG(drv_data);
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flag &= ~chip->flag;
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flag |= (chip->flag << 8);
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flag &= ~chip->flag;
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flag |= (chip->flag << 8);
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write_FLAG(drv_data, flag);
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write_FLAG(drv_data, flag);
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} else {
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gpio_set_value(chip->cs_gpio, 1);
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}
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/* Move delay here for consistency */
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if (chip->cs_chg_udelay)
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@ -1036,6 +1045,7 @@ static int bfin_spi_setup(struct spi_device *spi)
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struct bfin5xx_spi_chip *chip_info = NULL;
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struct chip_data *chip;
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struct driver_data *drv_data = spi_master_get_devdata(spi->master);
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int ret;
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/* Abort device setup if requested features are not supported */
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if (spi->mode & ~(SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST)) {
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@ -1081,6 +1091,7 @@ static int bfin_spi_setup(struct spi_device *spi)
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chip->bits_per_word = chip_info->bits_per_word;
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chip->cs_change_per_word = chip_info->cs_change_per_word;
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chip->cs_chg_udelay = chip_info->cs_chg_udelay;
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chip->cs_gpio = chip_info->cs_gpio;
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}
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/* translate common spi framework into our register */
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@ -1121,6 +1132,16 @@ static int bfin_spi_setup(struct spi_device *spi)
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chip->flag = 1 << (spi->chip_select);
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chip->chip_select_num = spi->chip_select;
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if (chip->chip_select_num == 0) {
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ret = gpio_request(chip->cs_gpio, spi->modalias);
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if (ret) {
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if (drv_data->dma_requested)
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free_dma(drv_data->dma_channel);
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return ret;
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}
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gpio_direction_output(chip->cs_gpio, 1);
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}
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switch (chip->bits_per_word) {
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case 8:
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chip->n_bytes = 1;
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@ -1186,6 +1207,9 @@ static void bfin_spi_cleanup(struct spi_device *spi)
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peripheral_free(ssel[spi->master->bus_num]
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[chip->chip_select_num-1]);
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if (chip->chip_select_num == 0)
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gpio_free(chip->cs_gpio);
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kfree(chip);
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}
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