Re: [PATCH] i2c:at91: Add device tree property to set clock-frequency

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Thanks for removing this hard coding bus frequency.

On Sun, Feb 23, 2014 at 03:19:00AM -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>

> ---
>  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..8e0871e 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);
> +	ret = of_property_read_u32(dev->dev->of_node, "clock-frequency",
> +			&bus_clk_rate);
> +	if (ret < 0)
> +		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
> 
--
To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux GPIO]     [Linux SPI]     [Linux Hardward Monitoring]     [LM Sensors]     [Linux USB Devel]     [Linux Media]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux