On Mon, Feb 24, 2014 at 08:50:45PM -0500, Marek Roszko wrote:
> This adds the ability to set "clock-frequency" in the device tree for the i2c bus 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@xxxxxxxxx>
Acked-by: Ludovic Desroches <ludovic.desroches@xxxxxxxxx>
Thanks
> ---
> v2:
> -fixed return code usage and check to not compare agaisnt less than zero
>
> ---
> Documentation/devicetree/bindings/i2c/i2c-at91.txt | 2 ++
> drivers/i2c/busses/i2c-at91.c | 10 ++++++++--
> 2 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-at91.txt b/Documentation/devicetree/bindings/i2c/i2c-at91.txt
> index 4fade84..388f0a2 100644
> --- 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 843d012..a407050 100644
> --- 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;
> + int 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");
> --
> 1.7.10.4
>
> --
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