spi/mxs: Make the SPI block clock speed configurable via DT
Add "clock-frequency" property, which allows configuring the SPI block's
base speed.
Signed-off-by: Marek Vasut <marex@denx.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/Documentation/devicetree/bindings/spi/mxs-spi.txt b/Documentation/devicetree/bindings/spi/mxs-spi.txt
index c36296f..e2e1395 100644
--- a/Documentation/devicetree/bindings/spi/mxs-spi.txt
+++ b/Documentation/devicetree/bindings/spi/mxs-spi.txt
@@ -6,6 +6,10 @@
- interrupts: Should contain SSP interrupts (error irq first, dma irq second)
- fsl,ssp-dma-channel: APBX DMA channel for the SSP
+Optional properties:
+- clock-frequency : Input clock frequency to the SPI block in Hz.
+ Default is 160000000 Hz.
+
Example:
ssp0: ssp@80010000 {
diff --git a/drivers/spi/spi-mxs.c b/drivers/spi/spi-mxs.c
index 556e5ef..edf1360 100644
--- a/drivers/spi/spi-mxs.c
+++ b/drivers/spi/spi-mxs.c
@@ -520,10 +520,17 @@
struct pinctrl *pinctrl;
struct clk *clk;
void __iomem *base;
- int devid, dma_channel;
+ int devid, dma_channel, clk_freq;
int ret = 0, irq_err, irq_dma;
dma_cap_mask_t mask;
+ /*
+ * Default clock speed for the SPI core. 160MHz seems to
+ * work reasonably well with most SPI flashes, so use this
+ * as a default. Override with "clock-frequency" DT prop.
+ */
+ const int clk_freq_default = 160000000;
+
iores = platform_get_resource(pdev, IORESOURCE_MEM, 0);
irq_err = platform_get_irq(pdev, 0);
irq_dma = platform_get_irq(pdev, 1);
@@ -555,12 +562,18 @@
"Failed to get DMA channel\n");
return -EINVAL;
}
+
+ ret = of_property_read_u32(np, "clock-frequency",
+ &clk_freq);
+ if (ret)
+ clk_freq = clk_freq_default;
} else {
dmares = platform_get_resource(pdev, IORESOURCE_DMA, 0);
if (!dmares)
return -EINVAL;
devid = pdev->id_entry->driver_data;
dma_channel = dmares->start;
+ clk_freq = clk_freq_default;
}
master = spi_alloc_master(&pdev->dev, sizeof(*spi));
@@ -598,12 +611,8 @@
goto out_master_free;
}
- /*
- * Crank up the clock to 120MHz, this will be further divided onto a
- * proper speed.
- */
clk_prepare_enable(ssp->clk);
- clk_set_rate(ssp->clk, 120 * 1000 * 1000);
+ clk_set_rate(ssp->clk, clk_freq);
ssp->clk_rate = clk_get_rate(ssp->clk) / 1000;
stmp_reset_block(ssp->base);