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| author | Andrey Smirnov <andrew.smirnov@gmail.com> | 2015-01-15 18:32:34 -0800 |
|---|---|---|
| committer | Sascha Hauer <s.hauer@pengutronix.de> | 2015-01-16 08:11:42 +0100 |
| commit | c39993fcdbbc1b3b59da6eaf12d7c09c2d70123e (patch) | |
| tree | 4f99185162984e6059ce1aa0072f34659d1756f1 /drivers/spi | |
| parent | 9130bd229c07b10ec0c0b0954abff4f96bcee686 (diff) | |
| download | barebox-c39993fcdbbc1b3b59da6eaf12d7c09c2d70123e.tar.gz barebox-c39993fcdbbc1b3b59da6eaf12d7c09c2d70123e.tar.xz | |
i.MX: SPI: Respect SPI_LSB_FIRST flag in mode settings
Add code to support SPI transfers that have data shifted out least
significant bit first. This is useful in many cases, but specifically
it is needed for drivers/firmware/altera_serial.c to work on i.MX
platform.
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Diffstat (limited to 'drivers/spi')
| -rw-r--r-- | drivers/spi/imx_spi.c | 41 |
1 files changed, 37 insertions, 4 deletions
diff --git a/drivers/spi/imx_spi.c b/drivers/spi/imx_spi.c index 3146339949..a1f19eba8b 100644 --- a/drivers/spi/imx_spi.c +++ b/drivers/spi/imx_spi.c @@ -137,6 +137,25 @@ static int imx_spi_setup(struct spi_device *spi) return 0; } +static unsigned int imx_spi_maybe_reverse_bits(struct spi_device *spi, unsigned int word) +{ + unsigned int result = word; + + if (spi->mode & SPI_LSB_FIRST) { + size_t bits_left = spi->bits_per_word - 1; + + for (word >>= 1; word; word >>= 1) { + result <<= 1; + result |= word & 1; + bits_left--; + } + + result <<= bits_left; + } + + return result; +} + static unsigned int cspi_0_0_xchg_single(struct imx_spi *imx, unsigned int data) { void __iomem *base = imx->regs; @@ -382,9 +401,20 @@ static void cspi_2_3_chipselect(struct spi_device *spi, int is_active) gpio_set_value(gpio, gpio_cs); } -static void imx_spi_do_transfer(struct spi_device *spi, struct spi_transfer *t) +static u32 imx_xchg_single(struct spi_device *spi, u32 tx_val) { + u32 rx_val; struct imx_spi *imx = container_of(spi->master, struct imx_spi, master); + + + tx_val = imx_spi_maybe_reverse_bits(spi, tx_val); + rx_val = imx->xchg_single(imx, tx_val); + + return imx_spi_maybe_reverse_bits(spi, rx_val); +} + +static void imx_spi_do_transfer(struct spi_device *spi, struct spi_transfer *t) +{ unsigned i; if (spi->bits_per_word <= 8) { @@ -393,7 +423,8 @@ static void imx_spi_do_transfer(struct spi_device *spi, struct spi_transfer *t) u8 rx_val; for (i = 0; i < t->len; i++) { - rx_val = imx->xchg_single(imx, tx_buf ? tx_buf[i] : 0); + rx_val = imx_xchg_single(spi, tx_buf ? tx_buf[i] : 0); + if (rx_buf) rx_buf[i] = rx_val; } @@ -403,7 +434,8 @@ static void imx_spi_do_transfer(struct spi_device *spi, struct spi_transfer *t) u16 rx_val; for (i = 0; i < t->len >> 1; i++) { - rx_val = imx->xchg_single(imx, tx_buf ? tx_buf[i] : 0); + rx_val = imx_xchg_single(spi, tx_buf ? tx_buf[i] : 0); + if (rx_buf) rx_buf[i] = rx_val; } @@ -413,7 +445,8 @@ static void imx_spi_do_transfer(struct spi_device *spi, struct spi_transfer *t) u32 rx_val; for (i = 0; i < t->len >> 2; i++) { - rx_val = imx->xchg_single(imx, tx_buf ? tx_buf[i] : 0); + rx_val = imx_xchg_single(spi, tx_buf ? tx_buf[i] : 0); + if (rx_buf) rx_buf[i] = rx_val; } |