On 1 August 2011 22:25, Ben Dooks [off-list ref] wrote:

On Sun, Jul 31, 2011 at 02:21:27AM +0800, Shawn Guo wrote:

quoted

It adds device tree probe support for i2c-imx driver.

Signed-off-by: Shawn Guo <redacted>
Cc: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
Cc: Darius Augulis <redacted>
Cc: Ben Dooks <redacted>
Acked-by: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
---
 .../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@83fc4000 { /* I2C2 on i.MX51 */
+     compatible = "fsl,imx51-i2c", "fsl,imx1-i2c";
+     reg = <0x83fc4000 0x4000>;
+     interrupts = <63>;
+};
+
+i2c@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

quoted

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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