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Commit 42c78b2b authored by Michael Hennerich's avatar Michael Hennerich Committed by Linus Torvalds
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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: default avatarMichael Hennerich <michael.hennerich@analog.com>
Signed-off-by: default avatarBryan Wu <cooloney@kernel.org>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e7d02e3c

arch/blackfin/include/asm/bfin5xx_spi.h

+1 −0
Original line number Diff line number Diff line
@@ -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_ */

drivers/spi/spi_bfin5xx.c

+32 −8
Original line number Diff line number Diff line
@@ -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)

{

	if (likely(chip->chip_select_num)) {

		u16 flag = read_FLAG(drv_data);



		flag |= chip->flag;

		flag &= ~(chip->flag << 8);



		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)

{

	if (likely(chip->chip_select_num)) {

		u16 flag = read_FLAG(drv_data);



		flag &= ~chip->flag;

		flag |= (chip->flag << 8);



		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);

}