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spi: stm32: add support for bits-per-word setting

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Implement the set_wordlen operation to allow dynamic bus width
configuration. This is required for peripherals with non-standard
requirements, such as display panels that need 9-bit word transfers
during the initialization and setup phase.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
This commit is contained in:
Dario Binacchi 2026-02-25 17:16:58 +01:00 committed by Patrice Chotard
parent dd5002856a
commit 011feb0028
1 changed files with 52 additions and 5 deletions
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57
drivers/spi/stm32_spi.c
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@ -384,6 +384,44 @@ static int stm32_spi_set_speed(struct udevice *bus, uint hz)
return 0;
}
static int _stm32_spi_set_wordlen(struct udevice *bus, unsigned int wordlen)
{
struct stm32_spi_priv *priv = dev_get_priv(bus);
struct stm32_spi_plat *plat = dev_get_plat(bus);
void __iomem *base = plat->base;
bool spi_enabled;
if ((wordlen - 1) < SPI_CFG1_DSIZE_MIN ||
(wordlen - 1) > SPI_CFG1_DSIZE) {
dev_err(bus, "Cannot set wordlen to %u [%d - %ld]\n",
wordlen, SPI_CFG1_DSIZE_MIN + 1,
SPI_CFG1_DSIZE + 1);
return -EINVAL;
}
spi_enabled = stm32_spi_is_enabled(plat->base);
if (spi_enabled)
stm32_spi_disable(plat->base);
dev_dbg(bus, "bits_per_word=%d\n", wordlen);
priv->cur_bpw = wordlen;
clrsetbits_le32(base + STM32_SPI_CFG1, SPI_CFG1_DSIZE,
priv->cur_bpw - 1);
if (spi_enabled)
stm32_spi_enable(plat->base);
return 0;
}
static int stm32_spi_set_wordlen(struct udevice *slave, unsigned int wordlen)
{
struct udevice *bus = dev_get_parent(slave);
return _stm32_spi_set_wordlen(bus, wordlen);
}
static int stm32_spi_xfer(struct udevice *slave, unsigned int bitlen,
const void *dout, void *din, unsigned long flags)
{
@ -397,11 +435,19 @@ static int stm32_spi_xfer(struct udevice *slave, unsigned int bitlen,
u32 xferlen;
u32 mode;
int xfer_status = 0;
int nb_words;
xferlen = bitlen / 8;
if (xferlen <= SPI_CR2_TSIZE)
writel(xferlen, base + STM32_SPI_CR2);
if (priv->cur_bpw <= 8)
nb_words = xferlen;
else if (priv->cur_bpw <= 16)
nb_words = DIV_ROUND_UP(xferlen * 8, 16);
else
nb_words = DIV_ROUND_UP(xferlen * 8, 32);
if (nb_words <= SPI_CR2_TSIZE)
writel(nb_words, base + STM32_SPI_CR2);
else
return -EMSGSIZE;
@ -409,6 +455,8 @@ static int stm32_spi_xfer(struct udevice *slave, unsigned int bitlen,
priv->rx_buf = din;
priv->tx_len = priv->tx_buf ? xferlen : 0;
priv->rx_len = priv->rx_buf ? xferlen : 0;
dev_dbg(bus, "bitlen: %d, xferlen: %d, nb_words: %d\n",
bitlen, xferlen, nb_words);
mode = SPI_FULL_DUPLEX;
if (!priv->tx_buf)
@ -570,9 +618,7 @@ static int stm32_spi_probe(struct udevice *dev)
priv->fifo_size = stm32_spi_get_fifo_size(dev);
priv->cur_mode = SPI_FULL_DUPLEX;
priv->cur_xferlen = 0;
priv->cur_bpw = SPI_DEFAULT_WORDLEN;
clrsetbits_le32(base + STM32_SPI_CFG1, SPI_CFG1_DSIZE,
priv->cur_bpw - 1);
_stm32_spi_set_wordlen(dev, SPI_DEFAULT_WORDLEN);
for (i = 0; i < ARRAY_SIZE(plat->cs_gpios); i++) {
if (!dm_gpio_is_valid(&plat->cs_gpios[i]))
@ -633,6 +679,7 @@ static const struct dm_spi_ops stm32_spi_ops = {
.release_bus = stm32_spi_release_bus,
.set_mode = stm32_spi_set_mode,
.set_speed = stm32_spi_set_speed,
.set_wordlen = stm32_spi_set_wordlen,
.xfer = stm32_spi_xfer,
};