Re: [PATCH] added device tree support to gpio-generic driver

From: Alexandre Courbot
Date: Mon Jun 08 2015 - 00:20:31 EST


On Fri, Jun 5, 2015 at 3:51 PM, Romain Baeriswyl
<romain.baeriswyl@xxxxxxxxxxx> wrote:
> ---

Your patch is missing a detailed commit message.

> .../devicetree/bindings/gpio/gpio-generic.txt | 19 +++++
> drivers/gpio/gpio-generic.c | 81 ++++++++++++++-----
> 2 files changed, 78 insertions(+), 22 deletions(-)
> create mode 100644 Documentation/devicetree/bindings/gpio/gpio-generic.txt
>
> diff --git a/Documentation/devicetree/bindings/gpio/gpio-generic.txt b/Documentation/devicetree/bindings/gpio/gpio-generic.txt
> new file mode 100644
> index 0000000..c2c4b98
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/gpio/gpio-generic.txt
> @@ -0,0 +1,19 @@
> +Bindings for gpio-generic
> +
> +Required properties:
> +- compatible : "basic-mmio-gpio" for little endian register access or
> + "basic-mmio-gpio-be" for big endian register access
> +- ngpios: Specifies the number of gpio mapped in the register. The value is
> + limited to the number of bits of the LONG type.
> +
> +Optional properties:
> +- base: Allows to forces the gpio number base offset used to index the gpio in
> + the device. If it is not see then the driver search autonoumously for
> + valid index range.

A base property for GPIO drivers is frown upon nowadays. >:/

> +
> +Examples:
> +
> + gpio_a {
> + compatible = "basic-mmio-gpio";
> + ngpios = <32>;
> + };
> diff --git a/drivers/gpio/gpio-generic.c b/drivers/gpio/gpio-generic.c
> index b92a690..9a4354c 100644
> --- a/drivers/gpio/gpio-generic.c
> +++ b/drivers/gpio/gpio-generic.c
> @@ -15,11 +15,11 @@
> * `.just a single "data" register, where GPIO state can be read and/or `
> * `,..written. ,,..``~~~~ .....``.`.`.~~.```.`.........``````.```````
> * `````````
> - ___
> -_/~~|___/~| . ```~~~~~~ ___/___\___ ,~.`.`.`.`````.~~...,,,,...
> -__________|~$@~~~ %~ /o*o*o*o*o*o\ .. Implementing such a GPIO .
> -o ` ~~~~\___/~~~~ ` controller in FPGA is ,.`
> - `....trivial..'~`.```.```
> + * ___
> + * _/~~|___/~| . ```~~~~~~ ___/___\___ ,~.`.`.`.`````.~~...,,,,...
> + * __________|~$@~~~ %~ /o*o*o*o*o*o\ .. Implementing such a GPIO .
> + * o ` ~~~~\___/~~~~ ` controller in FPGA is ,.`
> + * `....trivial..'~`.```.```

Comment fix? Why not, but this is not related to the subject of this
patch. Please do this in a separate patch.

> * ```````
> * .```````~~~~`..`.``.``.
> * . The driver supports `... ,..```.`~~~```````````````....````.``,,
> @@ -61,6 +61,8 @@ o ` ~~~~\___/~~~~ ` controller in FPGA is ,.`
> #include <linux/platform_device.h>
> #include <linux/mod_devicetable.h>
> #include <linux/basic_mmio_gpio.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
>
> static void bgpio_write8(void __iomem *reg, unsigned long data)
> {
> @@ -375,10 +377,9 @@ static int bgpio_setup_accessors(struct device *dev,
> dev_err(dev,
> "64 bit big endian byte order unsupported\n");
> return -EINVAL;
> - } else {
> - bgc->read_reg = bgpio_read64;
> - bgc->write_reg = bgpio_write64;
> }
> + bgc->read_reg = bgpio_read64;
> + bgc->write_reg = bgpio_write64;

Why change this? This if/else sequence was consistent with the other
cases, I think it would be better to keep it that way.

> break;
> #endif /* BITS_PER_LONG >= 64 */
> default:
> @@ -564,6 +565,27 @@ static void __iomem *bgpio_map(struct platform_device *pdev,
> return ret;
> }
>
> +static const struct platform_device_id bgpio_id_table[] = {
> + { "basic-mmio-gpio",
> + .driver_data = 0,
> + }, { "basic-mmio-gpio-be",
> + .driver_data = BGPIOF_BIG_ENDIAN
> + },
> + { },
> +};

Formatting is wrong here. Please keep the same formatting as the
original statement.

> +MODULE_DEVICE_TABLE(platform, bgpio_id_table);
> +
> +static const struct of_device_id bgpio_dt_ids[] = {
> + { .compatible = "basic-mmio-gpio",

Same remark about formatting.

> + .data = bgpio_id_table + 0

I would probably prefer &bgpio_id_table[0], but your call.

> + },
> + { .compatible = "basic-mmio-gpio-be",
> + .data = bgpio_id_table + 1
> + },

Instead of having two different compatible strings, how about making
the big-endian option a boolean DT property?

> + { }
> +};
> +MODULE_DEVICE_TABLE(of, bgpio_dt_ids);
> +
> static int bgpio_pdev_probe(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> @@ -574,10 +596,37 @@ static int bgpio_pdev_probe(struct platform_device *pdev)
> void __iomem *dirout;
> void __iomem *dirin;
> unsigned long sz;
> - unsigned long flags = pdev->id_entry->driver_data;
> + unsigned long flags;
> int err;
> struct bgpio_chip *bgc;
> - struct bgpio_pdata *pdata = dev_get_platdata(dev);
> + struct bgpio_pdata *pdata;
> +
> + if (of_have_populated_dt()) {
> + const struct of_device_id *of_id =
> + of_match_device(bgpio_dt_ids, dev);
> +
> + pdata = devm_kzalloc(dev, sizeof(struct bgpio_pdata),
> + GFP_KERNEL);
> + if (!pdata)
> + return -ENOMEM;
> +
> + if (of_property_read_u32(dev->of_node, "ngpio",
> + &pdata->ngpio)) {
> + dev_err(dev, "Failed to get field ngpio");
> + return -EINVAL;
> + }
> + if (of_property_read_u32(dev->of_node, "base", &pdata->base))
> + pdata->base = -1;
> +
> + dev->platform_data = pdata;
> +
> + if (of_id)
> + pdev->id_entry = of_id->data;
> + }

Could you move this to a bgpio_parse_dt() function to keep this
function short and clear?

> +
> + pdata = dev_get_platdata(dev);
> +
> + flags = pdev->id_entry->driver_data;
>
> r = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dat");
> if (!r)
> @@ -633,18 +682,6 @@ static int bgpio_pdev_remove(struct platform_device *pdev)
> return bgpio_remove(bgc);
> }
>
> -static const struct platform_device_id bgpio_id_table[] = {
> - {
> - .name = "basic-mmio-gpio",
> - .driver_data = 0,
> - }, {
> - .name = "basic-mmio-gpio-be",
> - .driver_data = BGPIOF_BIG_ENDIAN,
> - },
> - { }
> -};
> -MODULE_DEVICE_TABLE(platform, bgpio_id_table);
> -
> static struct platform_driver bgpio_driver = {
> .driver = {
> .name = "basic-mmio-gpio",
> --
> 1.7.1
>
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