Not all boards have the same CSB frequency, nor do every SPI slave necessarily support running at 16.7 MHz. So implement ->set_speed; that also allows using a smaller PM (i.e., 0) for slaves that do support a higher speed.
Based on work by Klaus H. Sørensen.
Cc: Klaus H. Sorensen khso@prevas.dk Signed-off-by: Rasmus Villemoes rasmus.villemoes@prevas.dk --- drivers/spi/mpc8xxx_spi.c | 64 ++++++++++++++++++++++++++++++++------- 1 file changed, 53 insertions(+), 11 deletions(-)
diff --git a/drivers/spi/mpc8xxx_spi.c b/drivers/spi/mpc8xxx_spi.c index 8ef2451411..1bde31ad34 100644 --- a/drivers/spi/mpc8xxx_spi.c +++ b/drivers/spi/mpc8xxx_spi.c @@ -5,6 +5,7 @@ */
#include <common.h> +#include <clk.h> #include <dm.h> #include <errno.h> #include <malloc.h> @@ -28,6 +29,7 @@ enum {
SPI_MODE_LEN_MASK = 0xf00000, SPI_MODE_LEN_SHIFT = 20, + SPI_MODE_PM_SHIFT = 16, SPI_MODE_PM_MASK = 0xf0000,
SPI_COM_LST = BIT(31 - 9), @@ -37,24 +39,19 @@ struct mpc8xxx_priv { spi8xxx_t *spi; struct gpio_desc gpios[16]; int cs_count; + ulong clk_rate; };
-static inline u32 to_prescale_mod(u32 val) -{ - return (min(val, (u32)15) << 16); -} - #define SPI_TIMEOUT 1000
static int mpc8xxx_spi_ofdata_to_platdata(struct udevice *dev) { struct mpc8xxx_priv *priv = dev_get_priv(dev); + struct clk clk; int ret;
priv->spi = (spi8xxx_t *)dev_read_addr(dev);
- /* TODO(mario.six@gdsys.cc): Read clock and save the value */ - ret = gpio_request_list_by_name(dev, "gpios", priv->gpios, ARRAY_SIZE(priv->gpios), GPIOD_IS_OUT | GPIOD_ACTIVE_LOW); if (ret < 0) @@ -62,6 +59,18 @@ static int mpc8xxx_spi_ofdata_to_platdata(struct udevice *dev)
priv->cs_count = ret;
+ ret = clk_get_by_index(dev, 0, &clk); + if (ret) { + dev_err(dev, "%s: clock not defined\n", __func__); + return ret; + } + + priv->clk_rate = clk_get_rate(&clk); + if (!priv->clk_rate) { + dev_err(dev, "%s: failed to get clock rate\n", __func__); + return -EINVAL; + } + return 0; }
@@ -79,10 +88,6 @@ static int mpc8xxx_spi_probe(struct udevice *dev) /* set len to 8 bits */ setbits_be32(&spi->mode, (8 - 1) << SPI_MODE_LEN_SHIFT);
- /* TODO(mario.six@gdsys.cc): This only ever sets one fixed speed */ - /* Use SYSCLK / 8 (16.67MHz typ.) */ - clrsetbits_be32(&spi->mode, SPI_MODE_PM_MASK, to_prescale_mod(1)); - setbits_be32(&spi->mode, SPI_MODE_EN);
/* Clear all SPI events */ @@ -204,6 +209,43 @@ static int mpc8xxx_spi_xfer(struct udevice *dev, uint bitlen,
static int mpc8xxx_spi_set_speed(struct udevice *dev, uint speed) { + struct mpc8xxx_priv *priv = dev_get_priv(dev); + spi8xxx_t *spi = priv->spi; + u32 bits, mask, div16, pm; + u32 mode; + ulong clk; + + clk = priv->clk_rate; + if (clk / 64 > speed) { + div16 = SPI_MODE_DIV16; + clk /= 16; + } else { + div16 = 0; + } + pm = (clk - 1)/(4*speed) + 1; + if (pm > 16) { + dev_err(dev, "requested speed %u too small\n", speed); + return -EINVAL; + } + pm--; + + bits = div16 | (pm << SPI_MODE_PM_SHIFT); + mask = SPI_MODE_DIV16 | SPI_MODE_PM_MASK; + mode = in_be32(&spi->mode); + if ((mode & mask) != bits) { + /* Must clear mode[EN] while changing speed. */ + mode &= ~(mask | SPI_MODE_EN); + out_be32(&spi->mode, mode); + mode |= bits; + out_be32(&spi->mode, mode); + mode |= SPI_MODE_EN; + out_be32(&spi->mode, mode); + } + + debug("requested speed %u, set speed to %lu/(%s4*%u) == %lu\n", + speed, priv->clk_rate, div16 ? "16*" : "", pm + 1, + clk/(4*(pm + 1))); + return 0; }