spi: img-spfi: check for max speed supported by the spfi block
Maximum speed supported by spfi is limited to 1/4 of the spfi clock.
But in some SoCs the maximum speed supported by the spfi block can
be limited to less than 1/4 of the spfi clock. In such cases we have
to define the limit in the device tree so that the driver can pick
it up.
Signed-off-by: Sifan Naeem <sifan.naeem@imgtec.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/drivers/spi/spi-img-spfi.c b/drivers/spi/spi-img-spfi.c
index 788e2b1..f31d792 100644
--- a/drivers/spi/spi-img-spfi.c
+++ b/drivers/spi/spi-img-spfi.c
@@ -546,6 +546,7 @@
struct img_spfi *spfi;
struct resource *res;
int ret;
+ u32 max_speed_hz;
master = spi_alloc_master(&pdev->dev, sizeof(*spfi));
if (!master)
@@ -610,6 +611,19 @@
master->max_speed_hz = clk_get_rate(spfi->spfi_clk) / 4;
master->min_speed_hz = clk_get_rate(spfi->spfi_clk) / 512;
+ /*
+ * Maximum speed supported by spfi is limited to the lower value
+ * between 1/4 of the SPFI clock or to "spfi-max-frequency"
+ * defined in the device tree.
+ * If no value is defined in the device tree assume the maximum
+ * speed supported to be 1/4 of the SPFI clock.
+ */
+ if (!of_property_read_u32(spfi->dev->of_node, "spfi-max-frequency",
+ &max_speed_hz)) {
+ if (master->max_speed_hz > max_speed_hz)
+ master->max_speed_hz = max_speed_hz;
+ }
+
master->setup = img_spfi_setup;
master->cleanup = img_spfi_cleanup;
master->transfer_one = img_spfi_transfer_one;