i2c: at91: Add device tree property to set clock-frequency

This adds the ability to set "clock-frequency" in the device tree for the at91
i2cbus following the naming of other i2c bus implementations. If the property
is not set,the clock frequency will default to the previously used define
of 100KHz.

Signed-off-by: Marek Roszko <mark.roszko@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

diff --git a/Documentation/devicetree/bindings/i2c/i2c-at91.txt b/Documentation/devicetree/bindings/i2c/i2c-at91.txt
index 4fade84bea1662a7a005d7d283944f296de4521d..388f0a275fbacb4602b830889afb3643212231f4 100644 (file)
--- a/Documentation/devicetree/bindings/i2c/i2c-at91.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-at91.txt
@@ -12,6 +12,7 @@ Required properties :
 - clocks: phandles to input clocks.
 
 Optional properties:
+- clock-frequency: Desired I2C bus frequency in Hz, otherwise defaults to 100000
 - Child nodes conforming to i2c bus binding
 
 Examples :
@@ -23,6 +24,7 @@ i2c0: i2c@fff84000 {
        #address-cells = <1>;
        #size-cells = <0>;
        clocks = <&twi0_clk>;
+       clock-frequency = <400000>;
 
        24c512@50 {
                compatible = "24c512";

diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
index 56baf48fb996f8c07fb403254ef007a941dbe4a0..e95f9ba96790f8783d9b462072d8a25d92650668 100644 (file)
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -32,7 +32,7 @@
 #include <linux/slab.h>
 #include <linux/platform_data/dma-atmel.h>
 
-#define TWI_CLK_HZ             100000                  /* max 400 Kbits/s */
+#define DEFAULT_TWI_CLK_HZ             100000          /* max 400 Kbits/s */
 #define AT91_I2C_TIMEOUT       msecs_to_jiffies(100)   /* transfer timeout */
 #define AT91_I2C_DMA_THRESHOLD 8                       /* enable DMA if transfer size is bigger than this threshold */
 
@@ -711,6 +711,7 @@ static int at91_twi_probe(struct platform_device *pdev)
        struct resource *mem;
        int rc;
        u32 phy_addr;
+       u32 bus_clk_rate;
 
        dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
        if (!dev)
@@ -756,7 +757,12 @@ static int at91_twi_probe(struct platform_device *pdev)
                        dev->use_dma = true;
        }
 
-       at91_calc_twi_clock(dev, TWI_CLK_HZ);
+       rc = of_property_read_u32(dev->dev->of_node, "clock-frequency",
+                       &bus_clk_rate);
+       if (rc)
+               bus_clk_rate = DEFAULT_TWI_CLK_HZ;
+
+       at91_calc_twi_clock(dev, bus_clk_rate);
        at91_init_twi_bus(dev);
 
        snprintf(dev->adapter.name, sizeof(dev->adapter.name), "AT91");