diff options
| author | Johannes Holland <johannes.holland@infineon.com> | 2020-05-11 15:22:26 +0200 |
|---|---|---|
| committer | Jagan Teki <jagan@amarulasolutions.com> | 2020-07-09 20:58:06 +0530 |
| commit | 0e146993bb3da59d2c52515048405444f35f00ec (patch) | |
| tree | 297615bf836bef7798649ec1932b225d01eed60b /drivers | |
| parent | f247354708ec93e995cf61901adc6d728762b196 (diff) | |
spi: add support for all spi modes with soft spi
The spi bitbanging driver did not implement all spi modes properly. Add
code to support all spi modes, honoring soft_spi_set_mode() and
defaulting to spi mode 0. Previously, CPHA was implemented inversely
(defaulting to CPHA=1) and CPOL=1 was hardcoded.
Signed-off-by: Johannes Holland <johannes.holland@infineon.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/spi/soft_spi.c | 48 |
1 files changed, 37 insertions, 11 deletions
diff --git a/drivers/spi/soft_spi.c b/drivers/spi/soft_spi.c index e8d7758da0..153bbf8b25 100644 --- a/drivers/spi/soft_spi.c +++ b/drivers/spi/soft_spi.c @@ -61,10 +61,12 @@ static int soft_spi_sda(struct udevice *dev, int bit) static int soft_spi_cs_activate(struct udevice *dev) { struct udevice *bus = dev_get_parent(dev); + struct soft_spi_priv *priv = dev_get_priv(bus); struct soft_spi_platdata *plat = dev_get_platdata(bus); + int cidle = !!(priv->mode & SPI_CPOL); dm_gpio_set_value(&plat->cs, 0); - dm_gpio_set_value(&plat->sclk, 0); + dm_gpio_set_value(&plat->sclk, cidle); /* to idle */ dm_gpio_set_value(&plat->cs, 1); return 0; @@ -82,11 +84,14 @@ static int soft_spi_cs_deactivate(struct udevice *dev) static int soft_spi_claim_bus(struct udevice *dev) { + struct udevice *bus = dev_get_parent(dev); + struct soft_spi_priv *priv = dev_get_priv(bus); + int cidle = !!(priv->mode & SPI_CPOL); /* * Make sure the SPI clock is in idle state as defined for * this slave. */ - return soft_spi_scl(dev, 0); + return soft_spi_scl(dev, cidle); } static int soft_spi_release_bus(struct udevice *dev) @@ -117,7 +122,8 @@ static int soft_spi_xfer(struct udevice *dev, unsigned int bitlen, uchar tmpdout = 0; const u8 *txd = dout; u8 *rxd = din; - int cpha = priv->mode & SPI_CPHA; + int cpha = !!(priv->mode & SPI_CPHA); + int cidle = !!(priv->mode & SPI_CPOL); unsigned int j; debug("spi_xfer: slave %s:%s dout %08X din %08X bitlen %u\n", @@ -143,22 +149,42 @@ static int soft_spi_xfer(struct udevice *dev, unsigned int bitlen, tmpdin = 0; } - if (!cpha) - soft_spi_scl(dev, 0); + /* + * CPOL 0: idle is low (0), active is high (1) + * CPOL 1: idle is high (1), active is low (0) + */ + + /* + * drive bit + * CPHA 1: CLK from idle to active + */ + if (cpha) + soft_spi_scl(dev, !cidle); if ((plat->flags & SPI_MASTER_NO_TX) == 0) soft_spi_sda(dev, !!(tmpdout & 0x80)); udelay(plat->spi_delay_us); - if (cpha) - soft_spi_scl(dev, 0); + + /* + * sample bit + * CPHA 0: CLK from idle to active + * CPHA 1: CLK from active to idle + */ + if (!cpha) + soft_spi_scl(dev, !cidle); else - soft_spi_scl(dev, 1); + soft_spi_scl(dev, cidle); tmpdin <<= 1; if ((plat->flags & SPI_MASTER_NO_RX) == 0) tmpdin |= dm_gpio_get_value(&plat->miso); tmpdout <<= 1; udelay(plat->spi_delay_us); - if (cpha) - soft_spi_scl(dev, 1); + + /* + * drive bit + * CPHA 0: CLK from active to idle + */ + if (!cpha) + soft_spi_scl(dev, cidle); } /* * If the number of bits isn't a multiple of 8, shift the last @@ -179,7 +205,7 @@ static int soft_spi_xfer(struct udevice *dev, unsigned int bitlen, static int soft_spi_set_speed(struct udevice *dev, unsigned int speed) { - /* Accept any speed */ + /* Ignore any speed settings. Speed is implemented via "spi-delay-us" */ return 0; } |