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

From: Romain Baeriswyl
Date: Mon Jun 08 2015 - 02:26:47 EST



On 2015-06-08 06:19, Alexandre Courbot wrote:
> 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. >:/
>
OK, I will remove it.

>> +
>> +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.
>
I just added the '*' to have the checkpatch.pl passing.

>> * ```````
>> * .```````~~~~`..`.``.``.
>> * . 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.
>
The else is actually not required as there is a return in the first
case. This change was also suggested by checkpatch.pl.

>> 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.
>
OK

>> +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?
>
I wanted to keep this device tree version aligned with the platform data
version.

>> + { }
>> +};
>> +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?
>
OK

>> +
>> + 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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>>
>>
>>
>>

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