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spi: img-spfi: check for max speed supported by the spfi block

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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>
This commit is contained in:
Sifan Naeem 2015-06-18 13:27:12 +01:00 committed by Mark Brown
parent d770e558e2
commit 93e3a9e999
2 changed files with 15 additions and 0 deletions
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1
Documentation/devicetree/bindings/spi/spi-img-spfi.txt
View File

@ -21,6 +21,7 @@ Required properties:
Optional properties:
- img,supports-quad-mode: Should be set if the interface supports quad mode
SPI transfers.
- spfi-max-frequency: Maximum speed supported by the spfi block.
Example:

14
drivers/spi/spi-img-spfi.c
View File

@ -546,6 +546,7 @@ static int img_spfi_probe(struct platform_device *pdev)
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 @@ static int img_spfi_probe(struct platform_device *pdev)
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;