[PATCH] spi/mxs: Make the SPI block clock speed configurable via DT
From: marex@denx.de (Marek Vasut)
Date: 2012-08-22 20:38:35
Also in:
linux-spi
Subsystem:
open firmware and flattened device tree bindings, spi subsystem, the rest · Maintainers:
Rob Herring, Krzysztof Kozlowski, Conor Dooley, Mark Brown, Linus Torvalds
Add "clock-frequency" property, which allows configuring the SPI block's base speed. Signed-off-by: Marek Vasut <marex@denx.de> Cc: Chris Ball <redacted> Cc: Shawn Guo <redacted> Cc: Mark Brown <redacted> --- Documentation/devicetree/bindings/spi/mxs-spi.txt | 4 ++++ drivers/spi/spi-mxs.c | 21 +++++++++++++++------ 2 files changed, 19 insertions(+), 6 deletions(-)
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 @@ Required properties: - 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 at 80010000 {
diff --git a/drivers/spi/spi-mxs.c b/drivers/spi/spi-mxs.c
index 130a436..331f600 100644
--- a/drivers/spi/spi-mxs.c
+++ b/drivers/spi/spi-mxs.c@@ -485,10 +485,17 @@ static int __devinit mxs_spi_probe(struct platform_device *pdev) 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);
@@ -520,12 +527,18 @@ static int __devinit mxs_spi_probe(struct platform_device *pdev) "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));
@@ -561,12 +574,8 @@ static int __devinit mxs_spi_probe(struct platform_device *pdev) 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);
--
1.7.10.4