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spi: spi-gpio: add SPI_3WIRE support 

Add SPI_3WIRE support to spi-gpio controller introducing
set_line_direction function pointer in spi_bitbang data structure.
Spi-gpio controller has been tested using hts221 temp/rh iio sensor
running in 3wire mode and lsm6dsm running in 4wire mode

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Lorenzo Bianconi 2018-07-28 10:19:14 +02:00 committed by Mark Brown
parent 304d34360b
commit 4b859db2c6
No known key found for this signature in database
GPG Key ID: 24D68B725D5487D0
3 changed files with 33 additions and 1 deletions
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16
drivers/spi/spi-bitbang.c
View File

@ -243,7 +243,23 @@ static int spi_bitbang_bufs(struct spi_device *spi, struct spi_transfer *t)
{
struct spi_bitbang_cs *cs = spi->controller_state;
unsigned nsecs = cs->nsecs;
struct spi_bitbang *bitbang;
bitbang = spi_master_get_devdata(spi->master);
if (bitbang->set_line_direction) {
int err;
err = bitbang->set_line_direction(spi, !!(t->tx_buf));
if (err < 0)
return err;
}
if (spi->mode & SPI_3WIRE) {
unsigned flags;
flags = t->tx_buf ? SPI_MASTER_NO_RX : SPI_MASTER_NO_TX;
return cs->txrx_bufs(spi, cs->txrx_word, nsecs, t, flags);
}
return cs->txrx_bufs(spi, cs->txrx_word, nsecs, t, 0);
}

17
drivers/spi/spi-gpio.c
View File

@ -121,7 +121,10 @@ static inline int getmiso(const struct spi_device *spi)
{
struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
return !!gpiod_get_value_cansleep(spi_gpio->miso);
if (spi->mode & SPI_3WIRE)
return !!gpiod_get_value_cansleep(spi_gpio->mosi);
else
return !!gpiod_get_value_cansleep(spi_gpio->miso);
}
/*
@ -250,6 +253,16 @@ static int spi_gpio_setup(struct spi_device *spi)
return status;
}
static int spi_gpio_set_direction(struct spi_device *spi, bool output)
{
struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
if (output)
return gpiod_direction_output(spi_gpio->mosi, 1);
else
return gpiod_direction_input(spi_gpio->mosi);
}
static void spi_gpio_cleanup(struct spi_device *spi)
{
spi_bitbang_cleanup(spi);
@ -395,6 +408,7 @@ static int spi_gpio_probe(struct platform_device *pdev)
return status;
master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32);
master->mode_bits = SPI_3WIRE | SPI_CPHA | SPI_CPOL;
master->flags = master_flags;
master->bus_num = pdev->id;
/* The master needs to think there is a chipselect even if not connected */
@ -407,6 +421,7 @@ static int spi_gpio_probe(struct platform_device *pdev)
spi_gpio->bitbang.master = master;
spi_gpio->bitbang.chipselect = spi_gpio_chipselect;
spi_gpio->bitbang.set_line_direction = spi_gpio_set_direction;
if ((master_flags & (SPI_MASTER_NO_TX | SPI_MASTER_NO_RX)) == 0) {
spi_gpio->bitbang.txrx_word[SPI_MODE_0] = spi_gpio_txrx_word_mode0;

1
include/linux/spi/spi_bitbang.h
View File

@ -31,6 +31,7 @@ struct spi_bitbang {
u32 (*txrx_word[4])(struct spi_device *spi,
unsigned nsecs,
u32 word, u8 bits, unsigned flags);
int (*set_line_direction)(struct spi_device *spi, bool output);
};
/* you can call these default bitbang->master methods from your custom