[PATCH v2 2/2] i2c/imx: add device tree probe support

Tue Aug 2 18:35:59 EST 2011

On 1 August 2011 22:25, Ben Dooks <ben-i2c at fluff.org> wrote:
> On Sun, Jul 31, 2011 at 02:21:27AM +0800, Shawn Guo wrote:
>> It adds device tree probe support for i2c-imx driver.
>>
>> Signed-off-by: Shawn Guo <shawn.guo at linaro.org>
>> Cc: Grant Likely <grant.likely at secretlab.ca>
>> Cc: Darius Augulis <augulis.darius at gmail.com>
>> Cc: Ben Dooks <ben-linux at fluff.org>
>> Acked-by: Grant Likely <grant.likely at secretlab.ca>
>> ---
>>  .../devicetree/bindings/i2c/fsl-imx-i2c.txt        |   25 ++++++++++++++++++++
>>  drivers/i2c/busses/i2c-imx.c                       |   25 +++++++++++++++----
>>  2 files changed, 44 insertions(+), 6 deletions(-)
>>  create mode 100644 Documentation/devicetree/bindings/i2c/fsl-imx-i2c.txt
>>
>> diff --git a/Documentation/devicetree/bindings/i2c/fsl-imx-i2c.txt b/Documentation/devicetree/bindings/i2c/fsl-imx-i2c.txt
>> new file mode 100644
>> index 0000000..f3cf43b
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/i2c/fsl-imx-i2c.txt
>> @@ -0,0 +1,25 @@
>> +* Freescale Inter IC (I2C) and High Speed Inter IC (HS-I2C) for i.MX
>> +
>> +Required properties:
>> +- compatible : Should be "fsl,<chip>-i2c"
>> +- reg : Should contain I2C/HS-I2C registers location and length
>> +- interrupts : Should contain I2C/HS-I2C interrupt
>> +
>> +Optional properties:
>> +- clock-frequency : Constains desired I2C/HS-I2C bus clock frequency in Hz.
>> +  The absence of the propoerty indicates the default frequency 100 kHz.
>> +
>> +Examples:
>> +
>> +i2c at 83fc4000 { /* I2C2 on i.MX51 */
>> +     compatible = "fsl,imx51-i2c", "fsl,imx1-i2c";
>> +     reg = <0x83fc4000 0x4000>;
>> +     interrupts = <63>;
>> +};
>> +
>> +i2c at 70038000 { /* HS-I2C on i.MX51 */
>> +     compatible = "fsl,imx51-i2c", "fsl,imx1-i2c";
>> +     reg = <0x70038000 0x4000>;
>> +     interrupts = <64>;
>> +     clock-frequency = <400000>;
>> +};
>
> It occurs to me that the clock-frequency field should be a standard
> used by all of-i2c drivers? could we have a standardised set of
> properties and a standard chunk of code that reads them?
>
Yes, "clock-frequency" is a common property for all clock frequency
binding, not only for of-i2c but all drivers that need to get clock
frequency from device tree.  And it's a u32 and being read by the
common OF API of_property_read_u32().  So to answer your question,
both the binding and code have already been standard.

Regards,
Shawn

>> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
>> index 54d809e..58832e5 100644
>> --- a/drivers/i2c/busses/i2c-imx.c
>> +++ b/drivers/i2c/busses/i2c-imx.c
>> @@ -48,6 +48,9 @@
>>  #include <linux/platform_device.h>
>>  #include <linux/clk.h>
>>  #include <linux/slab.h>
>> +#include <linux/of.h>
>> +#include <linux/of_device.h>
>> +#include <linux/of_i2c.h>
>>
>>  #include <mach/irqs.h>
>>  #include <mach/hardware.h>
>> @@ -125,6 +128,11 @@ struct imx_i2c_struct {
>>       unsigned int            ifdr; /* IMX_I2C_IFDR */
>>  };
>>
>> +static const struct of_device_id i2c_imx_dt_ids[] = {
>> +     { .compatible = "fsl,imx1-i2c", },
>> +     { /* sentinel */ }
>> +};
>> +
>>  /** Functions for IMX I2C adapter driver ***************************************
>>  *******************************************************************************/
>>
>> @@ -469,7 +477,7 @@ static int __init i2c_imx_probe(struct platform_device *pdev)
>>       struct imxi2c_platform_data *pdata = pdev->dev.platform_data;
>>       void __iomem *base;
>>       resource_size_t res_size;
>> -     int irq;
>> +     int irq, bitrate;
>>       int ret;
>>
>>       dev_dbg(&pdev->dev, "<%s>\n", __func__);
>> @@ -512,6 +520,7 @@ static int __init i2c_imx_probe(struct platform_device *pdev)
>>       i2c_imx->adapter.algo           = &i2c_imx_algo;
>>       i2c_imx->adapter.dev.parent     = &pdev->dev;
>>       i2c_imx->adapter.nr             = pdev->id;
>> +     i2c_imx->adapter.dev.of_node    = pdev->dev.of_node;
>>       i2c_imx->irq                    = irq;
>>       i2c_imx->base                   = base;
>>       i2c_imx->res                    = res;
>> @@ -538,10 +547,12 @@ static int __init i2c_imx_probe(struct platform_device *pdev)
>>       i2c_set_adapdata(&i2c_imx->adapter, i2c_imx);
>>
>>       /* Set up clock divider */
>> -     if (pdata && pdata->bitrate)
>> -             i2c_imx_set_clk(i2c_imx, pdata->bitrate);
>> -     else
>> -             i2c_imx_set_clk(i2c_imx, IMX_I2C_BIT_RATE);
>> +     bitrate = IMX_I2C_BIT_RATE;
>> +     ret = of_property_read_u32(pdev->dev.of_node,
>> +                                "clock-frequency", &bitrate);
>> +     if (ret < 0 && pdata && pdata->bitrate)
>> +             bitrate = pdata->bitrate;
>> +     i2c_imx_set_clk(i2c_imx, bitrate);
>>
>>       /* Set up chip registers to defaults */
>>       writeb(0, i2c_imx->base + IMX_I2C_I2CR);
>> @@ -554,6 +565,8 @@ static int __init i2c_imx_probe(struct platform_device *pdev)
>>               goto fail5;
>>       }
>>
>> +     of_i2c_register_devices(&i2c_imx->adapter);
>> +
>>       /* Set up platform driver data */
>>       platform_set_drvdata(pdev, i2c_imx);
>>
>> @@ -584,7 +597,6 @@ fail1:
>>  static int __exit i2c_imx_remove(struct platform_device *pdev)
>>  {
>>       struct imx_i2c_struct *i2c_imx = platform_get_drvdata(pdev);
>> -     struct imxi2c_platform_data *pdata = pdev->dev.platform_data;
>>
>>       /* remove adapter */
>>       dev_dbg(&i2c_imx->adapter.dev, "adapter removed\n");
>> @@ -613,6 +625,7 @@ static struct platform_driver i2c_imx_driver = {
>>       .driver = {
>>               .name   = DRIVER_NAME,
>>               .owner  = THIS_MODULE,
>> +             .of_match_table = i2c_imx_dt_ids,
>>       }
>>  };
>>
>> --
>> 1.7.4.1
>>
>> --
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