Re: [PATCH v2 10/17] gpio: support ROHM BD71815 GPOs

[Bartosz Golaszewski <bgolaszewski@baylibre.com>]

On Tue, Jan 19, 2021 at 8:23 AM Matti Vaittinen
<matti.vaittinen@fi.rohmeurope.com> wrote:
>
> Support GPO(s) found from ROHM BD71815 power management IC. The IC has two
> GPO pins but only one is properly documented in data-sheet. The driver
> exposes by default only the documented GPO. The second GPO is connected to
> E5 pin and is marked as GND in data-sheet. Control for this undocumented
> pin can be enabled using a special DT property.
>
> This driver is derived from work by Peter Yang <yanglsh@embest-tech.com>
> although not so much of original is left.
>
> Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>

Hi Matti,

looks great, just a couple nits.

> ---
> Changes since v1:
>   - removed unneeded headers
>   - clarified dev/parent->dev usage
>   - removed forgotten #define DEBUG
>
>  drivers/gpio/Kconfig        |  10 +++
>  drivers/gpio/Makefile       |   1 +
>  drivers/gpio/gpio-bd71815.c | 171 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 182 insertions(+)
>  create mode 100644 drivers/gpio/gpio-bd71815.c
>
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index c70f46e80a3b..fd7283af858d 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -1096,6 +1096,16 @@ config GPIO_BD70528
>           This driver can also be built as a module. If so, the module
>           will be called gpio-bd70528.
>
> +config GPIO_BD71815
> +       tristate "ROHM BD71815 PMIC GPIO support"
> +       depends on MFD_ROHM_BD71828
> +       help
> +         Support for GPO(s) on ROHM BD71815 PMIC. There are two GPOs
> +         available on the ROHM PMIC.
> +
> +         This driver can also be built as a module. If so, the module
> +         will be called gpio-bd71815.
> +
>  config GPIO_BD71828
>         tristate "ROHM BD71828 GPIO support"
>         depends on MFD_ROHM_BD71828
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index 35e3b6026665..86bb680522a6 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -39,6 +39,7 @@ obj-$(CONFIG_GPIO_ATH79)              += gpio-ath79.o
>  obj-$(CONFIG_GPIO_BCM_KONA)            += gpio-bcm-kona.o
>  obj-$(CONFIG_GPIO_BCM_XGS_IPROC)       += gpio-xgs-iproc.o
>  obj-$(CONFIG_GPIO_BD70528)             += gpio-bd70528.o
> +obj-$(CONFIG_GPIO_BD71815)             += gpio-bd71815.o
>  obj-$(CONFIG_GPIO_BD71828)             += gpio-bd71828.o
>  obj-$(CONFIG_GPIO_BD9571MWV)           += gpio-bd9571mwv.o
>  obj-$(CONFIG_GPIO_BRCMSTB)             += gpio-brcmstb.o
> diff --git a/drivers/gpio/gpio-bd71815.c b/drivers/gpio/gpio-bd71815.c
> new file mode 100644
> index 000000000000..664de5f69bf1
> --- /dev/null
> +++ b/drivers/gpio/gpio-bd71815.c
> @@ -0,0 +1,171 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Support to GPOs on ROHM BD71815
> + */

Newline here.

> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/irq.h>
> +#include <linux/gpio/driver.h>
> +#include <linux/platform_device.h>
> +#include <linux/of.h>
> +/* For the BD71815 register definitions */
> +#include <linux/mfd/rohm-bd71815.h>
> +

Please arrange headers alphabetically.

> +struct bd71815_gpio {
> +       struct gpio_chip chip;
> +       struct device *dev;
> +       struct regmap *regmap;
> +       /*
> +        * Sigh. The BD71815 and BD71817 were originally designed to support two
> +        * GPO pins. At some point it was noticed the second GPO pin which is
> +        * the E5 pin located at the center of IC is hard to use on PCB (due to
> +        * the location). It was decided to not promote this second GPO and pin
> +        * is marked as GND on the data-sheet. The functionality is still there
> +        * though! I guess driving GPO connected to ground is a bad idea. Thus
> +        * we do not support it by default. OTOH - the original driver written
> +        * by colleagues at Embest did support controlling this second GPO. It
> +        * is thus possible this is used in some of the products.
> +        *
> +        * This driver does not by default support configuring this second GPO
> +        * but allows using it by providing the DT property
> +        * "rohm,enable-hidden-gpo".
> +        */
> +       bool e5_pin_is_gpo;
> +};
> +
> +static int bd71815gpo_get(struct gpio_chip *chip, unsigned int offset)
> +{
> +       struct bd71815_gpio *bd71815 = gpiochip_get_data(chip);
> +       int ret = 0;
> +       int val;
> +
> +       ret = regmap_read(bd71815->regmap, BD71815_REG_GPO, &val);
> +       if (ret)
> +               return ret;
> +
> +       return (val >> offset) & 1;
> +}
> +
> +static void bd71815gpo_set(struct gpio_chip *chip, unsigned int offset,
> +                          int value)
> +{
> +       struct bd71815_gpio *bd71815 = gpiochip_get_data(chip);
> +       int ret, val, mask;
> +
> +       if (!bd71815->e5_pin_is_gpo && offset)
> +               return;
> +
> +       mask = BIT(offset);
> +       val = value ? mask : 0;

Maybe use regmap_set/clear_bits() here?

> +       ret = regmap_update_bits(bd71815->regmap, BD71815_REG_GPO, mask, val);
> +       if (ret)
> +               dev_warn(bd71815->dev, "failed to toggle GPO\n");
> +}
> +
> +static int bd71815_gpio_set_config(struct gpio_chip *chip, unsigned int offset,
> +                                  unsigned long config)
> +{
> +       struct bd71815_gpio *bdgpio = gpiochip_get_data(chip);
> +
> +       if (!bdgpio->e5_pin_is_gpo && offset)
> +               return -EOPNOTSUPP;
> +
> +       switch (pinconf_to_config_param(config)) {
> +       case PIN_CONFIG_DRIVE_OPEN_DRAIN:
> +               return regmap_update_bits(bdgpio->regmap,
> +                                         BD71815_REG_GPO,
> +                                         BD71815_GPIO_DRIVE_MASK << offset,
> +                                         BD71815_GPIO_OPEN_DRAIN << offset);
> +       case PIN_CONFIG_DRIVE_PUSH_PULL:
> +               return regmap_update_bits(bdgpio->regmap,
> +                                         BD71815_REG_GPO,
> +                                         BD71815_GPIO_DRIVE_MASK << offset,
> +                                         BD71815_GPIO_CMOS << offset);
> +       default:
> +               break;
> +       }
> +       return -EOPNOTSUPP;
> +}
> +
> +/* BD71815 GPIO is actually GPO */
> +static int bd71815gpo_direction_get(struct gpio_chip *gc, unsigned int offset)
> +{
> +       return GPIO_LINE_DIRECTION_OUT;
> +}
> +
> +/* Template for GPIO chip */

So let's make it const?

> +static struct gpio_chip bd71815gpo_chip = {
> +       .label                  = "bd71815",
> +       .owner                  = THIS_MODULE,
> +       .get                    = bd71815gpo_get,
> +       .get_direction          = bd71815gpo_direction_get,
> +       .set                    = bd71815gpo_set,
> +       .set_config             = bd71815_gpio_set_config,
> +       .can_sleep              = 1,
> +};
> +
> +static int gpo_bd71815_probe(struct platform_device *pdev)
> +{
> +       int ret;
> +       struct bd71815_gpio *g;
> +       struct device *dev;
> +       struct device *parent;
> +
> +       /*
> +        * Bind devm lifetime to this platform device => use dev for devm.
> +        * also the prints should originate from this device.
> +        */
> +       dev = &pdev->dev;
> +       /* The device-tree and regmap come from MFD => use parent for that */
> +       parent = dev->parent;
> +
> +       g = devm_kzalloc(dev, sizeof(*g), GFP_KERNEL);
> +       if (!g)
> +               return -ENOMEM;
> +
> +       g->e5_pin_is_gpo = of_property_read_bool(parent->of_node,
> +                                                "rohm,enable-hidden-gpo");
> +       g->chip = bd71815gpo_chip;
> +       g->chip.base = -1;
> +
> +       if (g->e5_pin_is_gpo)
> +               g->chip.ngpio = 2;
> +       else
> +               g->chip.ngpio = 1;
> +
> +       g->chip.parent = parent;
> +       g->chip.of_node = parent->of_node;
> +       g->regmap = dev_get_regmap(parent, NULL);
> +       g->dev = dev;
> +
> +       ret = devm_gpiochip_add_data(dev, &g->chip, g);
> +       if (ret < 0) {
> +               dev_err(dev, "could not register gpiochip, %d\n", ret);
> +               return ret;
> +       }
> +
> +       return ret;
> +}
> +static const struct platform_device_id bd7181x_gpo_id[] = {
> +       { "bd71815-gpo" },
> +       { },
> +};
> +MODULE_DEVICE_TABLE(platform, bd7181x_gpo_id);
> +
> +static struct platform_driver gpo_bd71815_driver = {
> +       .driver = {
> +               .name   = "bd71815-gpo",
> +               .owner  = THIS_MODULE,
> +       },
> +       .probe          = gpo_bd71815_probe,
> +       .id_table       = bd7181x_gpo_id,
> +};
> +
> +module_platform_driver(gpo_bd71815_driver);
> +
> +/* Note:  this hardware lives inside an I2C-based multi-function device. */
> +MODULE_ALIAS("platform:bd71815-gpo");
> +
> +MODULE_AUTHOR("Peter Yang <yanglsh@embest-tech.com>");
> +MODULE_DESCRIPTION("GPO interface for BD71815");
> +MODULE_LICENSE("GPL");
> --
> 2.25.4
>

Bartosz

>
> --
> Matti Vaittinen, Linux device drivers
> ROHM Semiconductors, Finland SWDC
> Kiviharjunlenkki 1E
> 90220 OULU
> FINLAND
>
> ~~~ "I don't think so," said Rene Descartes. Just then he vanished ~~~
> Simon says - in Latin please.
> ~~~ "non cogito me" dixit Rene Descarte, deinde evanescavit ~~~
> Thanks to Simon Glass for the translation =]