Re: [PATCH v1 1/5] gpio: moxart: convert to use basic mmio gpio library

[Kamlakant Patel <kamlakant.patel@xxxxxxxxxx>]

Hi Alexandre,

On 4 December 2014 at 14:47, Alexandre Courbot <gnurou@xxxxxxxxx> wrote:
> On Mon, Dec 1, 2014 at 9:09 PM,  <kamlakant.patel@xxxxxxxxxx> wrote:
>> From: Kamlakant Patel <kamlakant.patel@xxxxxxxxxx>
>>
>> This patch converts MOXART GPIO driver to use basic_mmio_gpio
>> generic library.
>>
>> Signed-off-by: Kamlakant Patel <kamlakant.patel@xxxxxxxxxx>
>> Tested-by: Jonas Jensen <jonas.jensen@xxxxxxxxx>
>> ---
>>  drivers/gpio/Kconfig       |   1 +
>>  drivers/gpio/gpio-moxart.c | 101 ++++++++++++++-------------------------------
>>  2 files changed, 32 insertions(+), 70 deletions(-)
>>
>> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
>> index 0959ca9..3bd4d63 100644
>> --- a/drivers/gpio/Kconfig
>> +++ b/drivers/gpio/Kconfig
>> @@ -184,6 +184,7 @@ config GPIO_F7188X
>>  config GPIO_MOXART
>>         bool "MOXART GPIO support"
>>         depends on ARCH_MOXART
>> +       select GPIO_GENERIC
>>         help
>>           Select this option to enable GPIO driver for
>>           MOXA ART SoC devices.
>> diff --git a/drivers/gpio/gpio-moxart.c b/drivers/gpio/gpio-moxart.c
>> index 4661e18..122958f 100644
>> --- a/drivers/gpio/gpio-moxart.c
>> +++ b/drivers/gpio/gpio-moxart.c
>> @@ -23,21 +23,12 @@
>>  #include <linux/delay.h>
>>  #include <linux/timer.h>
>>  #include <linux/bitops.h>
>> +#include <linux/basic_mmio_gpio.h>
>>
>>  #define GPIO_DATA_OUT          0x00
>>  #define GPIO_DATA_IN           0x04
>>  #define GPIO_PIN_DIRECTION     0x08
>>
>> -struct moxart_gpio_chip {
>> -       struct gpio_chip gpio;
>> -       void __iomem *base;
>> -};
>> -
>> -static inline struct moxart_gpio_chip *to_moxart_gpio(struct gpio_chip *chip)
>> -{
>> -       return container_of(chip, struct moxart_gpio_chip, gpio);
>> -}
>> -
>>  static int moxart_gpio_request(struct gpio_chip *chip, unsigned offset)
>>  {
>>         return pinctrl_request_gpio(offset);
>> @@ -48,90 +39,60 @@ static void moxart_gpio_free(struct gpio_chip *chip, unsigned offset)
>>         pinctrl_free_gpio(offset);
>>  }
>>
>> -static void moxart_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
>> -{
>> -       struct moxart_gpio_chip *gc = to_moxart_gpio(chip);
>> -       void __iomem *ioaddr = gc->base + GPIO_DATA_OUT;
>> -       u32 reg = readl(ioaddr);
>> -
>> -       if (value)
>> -               reg = reg | BIT(offset);
>> -       else
>> -               reg = reg & ~BIT(offset);
>> -
>> -       writel(reg, ioaddr);
>> -}
>> -
>>  static int moxart_gpio_get(struct gpio_chip *chip, unsigned offset)
>>  {
>> -       struct moxart_gpio_chip *gc = to_moxart_gpio(chip);
>> -       u32 ret = readl(gc->base + GPIO_PIN_DIRECTION);
>> +       struct bgpio_chip *bgc = to_bgpio_chip(chip);
>> +       u32 ret = bgc->read_reg(bgc->reg_dir);
>>
>>         if (ret & BIT(offset))
>> -               return !!(readl(gc->base + GPIO_DATA_OUT) & BIT(offset));
>> +               return !!(bgc->read_reg(bgc->reg_set) & BIT(offset));
>>         else
>> -               return !!(readl(gc->base + GPIO_DATA_IN) & BIT(offset));
>> -}
>> -
>> -static int moxart_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
>> -{
>> -       struct moxart_gpio_chip *gc = to_moxart_gpio(chip);
>> -       void __iomem *ioaddr = gc->base + GPIO_PIN_DIRECTION;
>> -
>> -       writel(readl(ioaddr) & ~BIT(offset), ioaddr);
>> -       return 0;
>> -}
>> -
>> -static int moxart_gpio_direction_output(struct gpio_chip *chip,
>> -                                       unsigned offset, int value)
>> -{
>> -       struct moxart_gpio_chip *gc = to_moxart_gpio(chip);
>> -       void __iomem *ioaddr = gc->base + GPIO_PIN_DIRECTION;
>> -
>> -       moxart_gpio_set(chip, offset, value);
>> -       writel(readl(ioaddr) | BIT(offset), ioaddr);
>> -       return 0;
>> +               return !!(bgc->read_reg(bgc->reg_dat) & BIT(offset));
>>  }
>>
>> -static struct gpio_chip moxart_template_chip = {
>> -       .label                  = "moxart-gpio",
>> -       .request                = moxart_gpio_request,
>> -       .free                   = moxart_gpio_free,
>> -       .direction_input        = moxart_gpio_direction_input,
>> -       .direction_output       = moxart_gpio_direction_output,
>> -       .set                    = moxart_gpio_set,
>> -       .get                    = moxart_gpio_get,
>> -       .ngpio                  = 32,
>> -       .owner                  = THIS_MODULE,
>> -};
>> -
>>  static int moxart_gpio_probe(struct platform_device *pdev)
>>  {
>>         struct device *dev = &pdev->dev;
>>         struct resource *res;
>> -       struct moxart_gpio_chip *mgc;
>> +       struct bgpio_chip *bgc;
>> +       void __iomem *base;
>>         int ret;
>>
>> -       mgc = devm_kzalloc(dev, sizeof(*mgc), GFP_KERNEL);
>> -       if (!mgc)
>> +       bgc = devm_kzalloc(dev, sizeof(*bgc), GFP_KERNEL);
>> +       if (!bgc)
>>                 return -ENOMEM;
>> -       mgc->gpio = moxart_template_chip;
>>
>>         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> -       mgc->base = devm_ioremap_resource(dev, res);
>> -       if (IS_ERR(mgc->base))
>> -               return PTR_ERR(mgc->base);
>> +       base = devm_ioremap_resource(dev, res);
>> +       if (IS_ERR(base))
>> +               return PTR_ERR(base);
>>
>> -       mgc->gpio.dev = dev;
>> +       ret = bgpio_init(bgc, dev, 4, base + GPIO_DATA_IN,
>> +                   base + GPIO_DATA_OUT, NULL,
>> +                   base + GPIO_PIN_DIRECTION, NULL, 0);
>> +       if (ret) {
>> +               dev_err(&pdev->dev, "bgpio_init failed\n");
>> +               return ret;
>> +       }
>>
>> -       ret = gpiochip_add(&mgc->gpio);
>> +       bgc->gc.label = "moxart-gpio";
>> +       bgc->gc.request = moxart_gpio_request;
>> +       bgc->gc.free = moxart_gpio_free;
>> +       bgc->gc.get = moxart_gpio_get;
>> +       bgc->data = bgc->read_reg(bgc->reg_set);
>> +       bgc->gc.base = 0;
>
> Do we actually want all instances of this driver to clain GPIOs 0..31?
>

Here is what I got from Jonas in previous discussion:
...
Thanks, it works, tested on UC-7112-LX hardware.

I have one additional nit..

The GPIO base number is implicitly changed from 0 to 224
(ARCH_NR_GPIOS (256) - ngpio (32)) which happen because of
bgpio_init() (it sets base -1 / gpiochip_find_base() on
gpiochip_add()). Which is confusing since the valid range (from user
space) used to be 0-31. So on export we now get:

[root@zurkon ~]# echo 24 > /sys/class/gpio/export
    [   61.640000] gpio-24 (?): gpiod_request: status -517
    [   61.650000] export_store: status -19

I see other drivers explicitly set base after bgpio_init(), my
suggestion is that we do the same here e.g. :

> +       bgc->gc.label = "moxart-gpio";
> +       bgc->gc.request = moxart_gpio_request;
> +       bgc->gc.free = moxart_gpio_free;
> +       bgc->gc.get = moxart_gpio_get;
> +       bgc->data = bgc->read_reg(bgc->reg_set);
> +       bgc->gc.ngpio = 32;
> +       bgc->gc.dev = dev;
> +       bgc->gc.owner = THIS_MODULE;

bgc->gc.base = 0;

Tested-by: Jonas Jensen <jonas.jensen@xxxxxxxxx>
...
> If so,
>
> Acked-by: Alexandre Courbot <acourbot@xxxxxxxxxx>
>
> Since this patch greatly simplifies the code and has been properly tested.

Thanks,
Kamlakant Patel
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