mpc8xxx_spi: put max_cs to use
Currently, max_cs is write-only; it's just set in
mpc8xxx_spi_ofdata_to_platdata and not otherwise used.
My mpc8309 was always resetting during an "sf probe 0". It turns out
dm_gpio_set_dir_flags() was being called with garbage, since nothing
had initialized priv->gpios[0] - our device tree used "cs-gpios"
rather than "gpios", so gpio_request_list_by_name() had returned 0.
That would have been a lot easier to figure out if the chip select
index was sanity checked, so rename max_cs to cs_count, and reject a
xfer with a too large cs index.
Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
diff --git a/drivers/spi/mpc8xxx_spi.c b/drivers/spi/mpc8xxx_spi.c
index 1c7bf10..ac4d0a9 100644
--- a/drivers/spi/mpc8xxx_spi.c
+++ b/drivers/spi/mpc8xxx_spi.c
@@ -35,7 +35,7 @@
struct mpc8xxx_priv {
spi8xxx_t *spi;
struct gpio_desc gpios[16];
- int max_cs;
+ int cs_count;
};
static inline u32 to_prescale_mod(u32 val)
@@ -74,7 +74,7 @@
if (ret < 0)
return -EINVAL;
- priv->max_cs = ret;
+ priv->cs_count = ret;
return 0;
}
@@ -131,6 +131,11 @@
debug("%s: slave %s:%u dout %08X din %08X bitlen %u\n", __func__,
bus->name, platdata->cs, *(uint *)dout, *(uint *)din, bitlen);
+ if (platdata->cs >= priv->cs_count) {
+ dev_err(dev, "chip select index %d too large (cs_count=%d)\n",
+ platdata->cs, priv->cs_count);
+ return -EINVAL;
+ }
if (flags & SPI_XFER_BEGIN)
mpc8xxx_spi_cs_activate(dev);