Re: [PATCH] i2c-designware: add OF binding support

On Thu, Aug 4, 2011 at 10:52 PM, Rob Herring [off-list ref] wrote:

On 08/04/2011 10:45 AM, Rob Herring wrote:

quoted

Ben,

On 08/04/2011 04:12 AM, Ben Dooks wrote:

quoted

On Wed, Aug 03, 2011 at 03:04:23PM -0500, Rob Herring wrote:

quoted

From: Rob Herring <rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>

Add of_match_table and DT style i2c registration to designware i2c
driver.

Signed-off-by: Rob Herring <rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>
Cc: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
Cc: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
Cc: Ben Dooks <redacted>
Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
---
 Documentation/devicetree/bindings/i2c/dw-i2c.txt |   23 ++++++++++++++++++++++
 drivers/i2c/busses/i2c-designware.c              |   13 ++++++++++++
 2 files changed, 36 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/i2c/dw-i2c.txt

diff --git a/Documentation/devicetree/bindings/i2c/dw-i2c.txt b/Documentation/devicetree/bindings/i2c/dw-i2c.txt
new file mode 100644
index 0000000..cbcb404
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/dw-i2c.txt

@@ -0,0 +1,23 @@
+* Synopsys DesignWare I2C
+
+Required properties :
+
+ - compatible : should be "snps,designware-i2c"
+ - reg : Offset and length of the register set for the device
+ - interrupts : <IRQ> where IRQ is the interrupt number.
+
+Recommended properties :
+
+ - clock-frequency : desired I2C bus clock frequency in Hz.
+
+Example :
+
+   i2c@f0000 {
+           #address-cells = <1>;
+           #size-cells = <0>;
+           compatible = "snps,designware-i2c";
+           reg = <0xf0000 0x1000>;
+           interrupts = <11>;
+           clock-frequency = <400000>;
+   };
+

looks good to me.

quoted

diff --git a/drivers/i2c/busses/i2c-designware.c b/drivers/i2c/busses/i2c-designware.c
index b7a51c4..2911a49 100644
--- a/drivers/i2c/busses/i2c-designware.c
+++ b/drivers/i2c/busses/i2c-designware.c

@@ -37,6 +37,7 @@

 #include <linux/platform_device.h>
 #include <linux/io.h>
 #include <linux/slab.h>
+#include <linux/of_i2c.h>

 /*
  * Registers offset

@@ -770,12 +771,17 @@ static int __devinit dw_i2c_probe(struct platform_device *pdev)

    adap->algo = &i2c_dw_algo;
    adap->dev.parent = &pdev->dev;

+#ifdef CONFIG_OF
+   r = i2c_add_adapter(adap);
+#else
    adap->nr = pdev->id;
    r = i2c_add_numbered_adapter(adap);
+#endif

I would say that doing the #ifdef CONFIG_OF is dangerous here when we
are in a mixed OF/platform enviromnent as we're depending on compile
time selection.

I'm also wondering whether we have an of helper macro which takes
a pdev and gives you an adapter number either given on pdev->id or
-1 for the case when we're using the OF bindings.

It might be worth talking to Grant about setting pdev->id to -1 if we
are using an OF device.

As Grant said, that's already done and this hunk is not needed.

quoted

quoted

    if (r) {
            dev_err(&pdev->dev, "failure adding adapter\n");
            goto err_free_irq;
    }
+   of_i2c_register_devices(adap);

If we did that, we could add a of_i2c_register_adapter() call which
would take the platform device and then do the of_i2c_register_devices()
and do these steps.

Better yet, how about putting of_i2c_register_devices into
i2c_register_adapter? Everywhere that calls of_i2c_register_devices is
preceded by a call to i2c_add_numbered_adapter or i2c_add_adapter. It
seems logical to put it with i2c_scan_static_board_info. I'll prepare a
patch to add that and remove all the other callers unless you think
that's a bad idea.

Nevermind. That would be undoing this commit:

   of/i2c: Fix module load order issue caused by of_i2c.c

The other alternative would be to move the i2c dt parsing code into
drivers/i2c.  I'm already planning to do that for spi and gpio dt
parsing code.

g.