I never like that
the clock-frequency = <400000>; need to be set on each i2c device
and then the i2c subsystem need to choose the slowest
Best Regards,
J.
On Mar 6, 2014, at 9:48 PM, Mark Roszko <mark.roszko@xxxxxxxxx> wrote:
> CCing the subsystem maintainer because I left him out on the initial send.
>
> On Fri, Feb 28, 2014 at 6:05 AM, Ludovic Desroches
> <ludovic.desroches@xxxxxxxxx> wrote:
>> 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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>
>
>
> --
> Mark
>
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