On 27 August 2012 13:31, Heiko Stübner [off-list ref] wrote:

Hi Thomas,

thanks for your review:

Am Montag, 27. August 2012, 06:20:49 schrieb Thomas Abraham:

quoted

Hi Heiko,

On 26 August 2012 03:23, Heiko Stübner [off-list ref] wrote:

quoted

Until now the Exynos-SoC was the only Samsung-SoC supporting the GPIOs
via the device tree. This patch implements dt-support for the
s3c24xx arches.

The controllers contain only 3 cells, as the underlying gpio controller
does not support controlling the drive strength on a gpio level.

Tested with the gpio-keys driver on a s3c2416 based machine.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
---

 .../devicetree/bindings/gpio/gpio-samsung.txt      |   38 ++++++++++++
 drivers/gpio/gpio-samsung.c                        |   63
 ++++++++++++++++++++ 2 files changed, 101 insertions(+), 0 deletions(-)

diff --git a/Documentation/devicetree/bindings/gpio/gpio-samsung.txt

b/Documentation/devicetree/bindings/gpio/gpio-samsung.txt index
5375625..ce6a7d4 100644

--- a/Documentation/devicetree/bindings/gpio/gpio-samsung.txt
+++ b/Documentation/devicetree/bindings/gpio/gpio-samsung.txt

@@ -39,3 +39,41 @@ Example:
                #gpio-cells = <4>;
                gpio-controller;

        };

+
+
+Samsung S3C24XX GPIO Controller
+
+Required properties:
+- compatible: Compatible property value should be

"samsung,s3c24xx-gpio".

This is debatable, but I would choose to be specific here and use
"samsing,s3c2416-gpio". For instance, SoC's in s3c24xx family have
differing value for pull none/down/up.

Hmmm, but the logic to drive the gpio controller is the same for all arches.
The only difference is the number to use for the different pull up/down
settings. So I think the "samsung,s3c24xx-gpio" is ok but the documentation
should simply reflect the different pull settings.

Ok.

quoted

quoted

+
+- reg: Physical base address of the controller and length of memory
mapped +  region.
+
+- #gpio-cells: Should be 3. The syntax of the gpio specifier used by
client nodes +  should be the following with values derived from the SoC
user manual. +     <[phandle of the gpio controller node]
+      [pin number within the gpio controller]
+      [mux function]
+      [flags and pull up/down]
+
+  Values for gpio specifier:
+  - Pin number: depending on the controller a number from 0 up to 15.
+  - Flags and Pull Up/Down: 0 - Pull Up/Down Disabled.
+                            1 - Pull Down Enabled.
+                            3 - Pull Up Enabled.

As per s3c2416 user manual, 2 is used for Pull Up and 3 is listed as
reserved value. Any particular reason to use 3 here for pull up and
not 2 as per the user manual?

Sorry, copy and paste error :-)

Ok.

quoted

quoted

+          Bit 16 (0x00010000) - Input is active low.
+
+- gpio-controller: Specifies that the node is a gpio controller.
+- #address-cells: should be 1.
+- #size-cells: should be 1.

It would be informative to add information about the 'mux function'
cell here as well. Specifically, on how to handle the banks that have
an extended GPxSEL register that allow additional pin function
selection.

Will add a mux function description.

Until now I've never realised the existence of the GPxSEL registers, so thanks
for the pointer :-).

But is this used in the driver at all? All the setcfg/getcfg functions in
gpio-samsung.c only handle the GPxCON registers - I haven't found code to
handle the GPxSEL registers at all. So my guess is that this was never
implemented - or that I'm blind ;-) .

You are right, there is no code that is handling the GPxCON registers.

Thanks,
Thomas.

quoted

quoted

+
+Example:
+
+       gpa: gpio-controller@56000000 {
+               #address-cells = <1>;
+               #size-cells = <1>;
+               compatible = "samsung,s3c24xx-gpio";
+               reg = <0x56000000 0x10>;
+               #gpio-cells = <3>;
+               gpio-controller;
+       };

diff --git a/drivers/gpio/gpio-samsung.c b/drivers/gpio/gpio-samsung.c
index a150d2e..80a2817 100644
--- a/drivers/gpio/gpio-samsung.c
+++ b/drivers/gpio/gpio-samsung.c

@@ -938,6 +938,67 @@ static void __init samsung_gpiolib_add(struct

samsung_gpio_chip *chip)

                s3c_gpiolib_track(chip);

 }

+#if defined(CONFIG_PLAT_S3C24XX) && defined(CONFIG_OF)
+static int s3c24xx_gpio_xlate(struct gpio_chip *gc,
+                       const struct of_phandle_args *gpiospec, u32
*flags) +{
+       unsigned int pin;
+
+       if (WARN_ON(gc->of_gpio_n_cells < 3))
+               return -EINVAL;
+
+       if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells))
+               return -EINVAL;
+
+       if (gpiospec->args[0] > gc->ngpio)
+               return -EINVAL;
+
+       pin = gc->base + gpiospec->args[0];
+
+       if (s3c_gpio_cfgpin(pin, S3C_GPIO_SFN(gpiospec->args[1])))
+               pr_warn("gpio_xlate: failed to set pin function\n");
+       if (s3c_gpio_setpull(pin, gpiospec->args[2] & 0xffff))
+               pr_warn("gpio_xlate: failed to set pin pull up/down\n");
+
+       if (flags)
+               *flags = gpiospec->args[2] >> 16;
+
+       return gpiospec->args[0];
+}
+
+static const struct of_device_id s3c24xx_gpio_dt_match[] __initdata = {
+       { .compatible = "samsung,s3c24xx-gpio", },
+       {}
+};
+
+static __init void s3c24xx_gpiolib_attach_ofnode(struct
samsung_gpio_chip *chip, +
 u64 base, u64 offset) +{
+       struct gpio_chip *gc =  &chip->chip;
+       u64 address;
+
+       if (!of_have_populated_dt())
+               return;
+
+       address = chip->base ? base + ((u32)chip->base & 0xfff) : base +
offset; +       gc->of_node = of_find_matching_node_by_address(NULL,
+                       s3c24xx_gpio_dt_match, address);
+       if (!gc->of_node) {
+               pr_info("gpio: device tree node not found for gpio
controller" +                       " with base address %08llx\n",
address); +               return;
+       }
+       gc->of_gpio_n_cells = 3;
+       gc->of_xlate = s3c24xx_gpio_xlate;
+}
+#elif defined(CONFIG_PLAT_S3C24XX)
+static __init void s3c24xx_gpiolib_attach_ofnode(struct
samsung_gpio_chip *chip, +
 u64 base, u64 offset) +{
+       return;
+}
+#endif /* defined(CONFIG_PLAT_S3C24XX) && defined(CONFIG_OF) */
+

 static void __init s3c24xx_gpiolib_add_chips(struct samsung_gpio_chip
 *chip,

                                             int nr_chips, void __iomem
                                             *base)

 {

@@ -962,6 +1023,8 @@ static void __init s3c24xx_gpiolib_add_chips(struct

samsung_gpio_chip *chip,

                        gc->direction_output =
                        samsung_gpiolib_2bit_output;

                samsung_gpiolib_add(chip);

+
+               s3c24xx_gpiolib_attach_ofnode(chip, S3C24XX_PA_GPIO, i *
0x10);

        }

 }

--
1.7.2.3

Overall, this is patch looks fine.

Reviewed-by: Thomas Abraham <redacted>

Heiko