// SPDX-License-Identifier: GPL-2.0
/*
 * Support to GPOs on ROHM BD71815
 * Copyright 2021 ROHM Semiconductors.
 * Author: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
 *
 * Copyright 2014 Embest Technology Co. Ltd. Inc.
 * Author: yanglsh@embest-tech.com
 */

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

struct bd71815_gpio {
        /* chip.parent points the MFD which provides DT node and regmap */
        struct gpio_chip chip;
        /* dev points to the platform device for devm and prints */
        struct device *dev;
        struct regmap *regmap;
};

static int bd71815gpo_get(struct gpio_chip *chip, unsigned int offset)
{
        struct bd71815_gpio *bd71815 = gpiochip_get_data(chip);
        int ret, val;

        ret = regmap_read(bd71815->regmap, BD71815_REG_GPO, &val);
        if (ret)
                return ret;

        return (val >> offset) & 1;
}

static int bd71815gpo_set(struct gpio_chip *chip, unsigned int offset,
                          int value)
{
        struct bd71815_gpio *bd71815 = gpiochip_get_data(chip);
        int bit;

        bit = BIT(offset);

        if (value)
                return regmap_set_bits(bd71815->regmap, BD71815_REG_GPO, bit);

        return regmap_clear_bits(bd71815->regmap, BD71815_REG_GPO, bit);
}

static int bd71815_gpio_set_config(struct gpio_chip *chip, unsigned int offset,
                                   unsigned long config)
{
        struct bd71815_gpio *bdgpio = gpiochip_get_data(chip);

        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 -ENOTSUPP;
}

/* 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 */
static const 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              = true,
};

#define BD71815_TWO_GPIOS       GENMASK(1, 0)
#define BD71815_ONE_GPIO        BIT(0)

/*
 * 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 the pin is marked as GND in
 * the datasheet. The functionality is still there though! I guess driving a GPO
 * connected to the 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".
 */
static int bd71815_init_valid_mask(struct gpio_chip *gc,
                                   unsigned long *valid_mask,
                                   unsigned int ngpios)
{
        if (ngpios != 2)
                return 0;

        if (gc->parent && device_property_present(gc->parent,
                                                  "rohm,enable-hidden-gpo"))
                *valid_mask = BD71815_TWO_GPIOS;
        else
                *valid_mask = BD71815_ONE_GPIO;

        return 0;
}

static int gpo_bd71815_probe(struct platform_device *pdev)
{
        struct bd71815_gpio *g;
        struct device *parent, *dev;

        /*
         * 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->chip = bd71815gpo_chip;

        /*
         * FIXME: As writing of this the sysfs interface for GPIO control does
         * not respect the valid_mask. Do not trust it but rather set the ngpios
         * to 1 if "rohm,enable-hidden-gpo" is not given.
         *
         * This check can be removed later if the sysfs export is fixed and
         * if the fix is backported.
         *
         * For now it is safest to just set the ngpios though.
         */
        if (device_property_present(parent, "rohm,enable-hidden-gpo"))
                g->chip.ngpio = 2;
        else
                g->chip.ngpio = 1;

        g->chip.init_valid_mask = bd71815_init_valid_mask;
        g->chip.base = -1;
        g->chip.parent = parent;
        g->regmap = dev_get_regmap(parent, NULL);
        g->dev = dev;

        return devm_gpiochip_add_data(dev, &g->chip, g);
}

static struct platform_driver gpo_bd71815_driver = {
        .driver = {
                .name   = "bd71815-gpo",
        },
        .probe          = gpo_bd71815_probe,
};
module_platform_driver(gpo_bd71815_driver);

MODULE_ALIAS("platform:bd71815-gpo");
MODULE_AUTHOR("Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>");
MODULE_AUTHOR("Peter Yang <yanglsh@embest-tech.com>");
MODULE_DESCRIPTION("GPO interface for BD71815");
MODULE_LICENSE("GPL");