// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * RDC321x GPIO driver
 *
 * Copyright (C) 2008, Volker Weiss <dev@tintuc.de>
 * Copyright (C) 2007-2010 Florian Fainelli <florian@openwrt.org>
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/platform_device.h>
#include <linux/pci.h>
#include <linux/gpio/driver.h>
#include <linux/mfd/rdc321x.h>
#include <linux/slab.h>

struct rdc321x_gpio {
        spinlock_t              lock;
        struct pci_dev          *sb_pdev;
        u32                     data_reg[2];
        int                     reg1_ctrl_base;
        int                     reg1_data_base;
        int                     reg2_ctrl_base;
        int                     reg2_data_base;
        struct gpio_chip        chip;
};

/* read GPIO pin */
static int rdc_gpio_get_value(struct gpio_chip *chip, unsigned gpio)
{
        struct rdc321x_gpio *gpch;
        u32 value = 0;
        int reg;

        gpch = gpiochip_get_data(chip);
        reg = gpio < 32 ? gpch->reg1_data_base : gpch->reg2_data_base;

        spin_lock(&gpch->lock);
        pci_write_config_dword(gpch->sb_pdev, reg,
                                        gpch->data_reg[gpio < 32 ? 0 : 1]);
        pci_read_config_dword(gpch->sb_pdev, reg, &value);
        spin_unlock(&gpch->lock);

        return (1 << (gpio & 0x1f)) & value ? 1 : 0;
}

static void rdc_gpio_set_value_impl(struct gpio_chip *chip,
                                unsigned gpio, int value)
{
        struct rdc321x_gpio *gpch;
        int reg = (gpio < 32) ? 0 : 1;

        gpch = gpiochip_get_data(chip);

        if (value)
                gpch->data_reg[reg] |= 1 << (gpio & 0x1f);
        else
                gpch->data_reg[reg] &= ~(1 << (gpio & 0x1f));

        pci_write_config_dword(gpch->sb_pdev,
                        reg ? gpch->reg2_data_base : gpch->reg1_data_base,
                        gpch->data_reg[reg]);
}

/* set GPIO pin to value */
static int rdc_gpio_set_value(struct gpio_chip *chip, unsigned int gpio,
                              int value)
{
        struct rdc321x_gpio *gpch;

        gpch = gpiochip_get_data(chip);
        spin_lock(&gpch->lock);
        rdc_gpio_set_value_impl(chip, gpio, value);
        spin_unlock(&gpch->lock);

        return 0;
}

static int rdc_gpio_config(struct gpio_chip *chip,
                                unsigned gpio, int value)
{
        struct rdc321x_gpio *gpch;
        int err;
        u32 reg;

        gpch = gpiochip_get_data(chip);

        spin_lock(&gpch->lock);
        err = pci_read_config_dword(gpch->sb_pdev, gpio < 32 ?
                        gpch->reg1_ctrl_base : gpch->reg2_ctrl_base, &reg);
        if (err)
                goto unlock;

        reg |= 1 << (gpio & 0x1f);

        err = pci_write_config_dword(gpch->sb_pdev, gpio < 32 ?
                        gpch->reg1_ctrl_base : gpch->reg2_ctrl_base, reg);
        if (err)
                goto unlock;

        rdc_gpio_set_value_impl(chip, gpio, value);

unlock:
        spin_unlock(&gpch->lock);

        return pcibios_err_to_errno(err);
}

/* configure GPIO pin as input */
static int rdc_gpio_direction_input(struct gpio_chip *chip, unsigned gpio)
{
        return rdc_gpio_config(chip, gpio, 1);
}

/*
 * Cache the initial value of both GPIO data registers
 */
static int rdc321x_gpio_probe(struct platform_device *pdev)
{
        int err;
        struct resource *r;
        struct rdc321x_gpio *rdc321x_gpio_dev;
        struct rdc321x_gpio_pdata *pdata;

        pdata = dev_get_platdata(&pdev->dev);
        if (!pdata) {
                dev_err(&pdev->dev, "no platform data supplied\n");
                return -ENODEV;
        }

        rdc321x_gpio_dev = devm_kzalloc(&pdev->dev, sizeof(struct rdc321x_gpio),
                                        GFP_KERNEL);
        if (!rdc321x_gpio_dev)
                return -ENOMEM;

        r = platform_get_resource_byname(pdev, IORESOURCE_IO, "gpio-reg1");
        if (!r) {
                dev_err(&pdev->dev, "failed to get gpio-reg1 resource\n");
                return -ENODEV;
        }

        spin_lock_init(&rdc321x_gpio_dev->lock);
        rdc321x_gpio_dev->sb_pdev = pdata->sb_pdev;
        rdc321x_gpio_dev->reg1_ctrl_base = r->start;
        rdc321x_gpio_dev->reg1_data_base = r->start + 0x4;

        r = platform_get_resource_byname(pdev, IORESOURCE_IO, "gpio-reg2");
        if (!r) {
                dev_err(&pdev->dev, "failed to get gpio-reg2 resource\n");
                return -ENODEV;
        }

        rdc321x_gpio_dev->reg2_ctrl_base = r->start;
        rdc321x_gpio_dev->reg2_data_base = r->start + 0x4;

        rdc321x_gpio_dev->chip.label = "rdc321x-gpio";
        rdc321x_gpio_dev->chip.owner = THIS_MODULE;
        rdc321x_gpio_dev->chip.direction_input = rdc_gpio_direction_input;
        rdc321x_gpio_dev->chip.direction_output = rdc_gpio_config;
        rdc321x_gpio_dev->chip.get = rdc_gpio_get_value;
        rdc321x_gpio_dev->chip.set = rdc_gpio_set_value;
        rdc321x_gpio_dev->chip.base = 0;
        rdc321x_gpio_dev->chip.ngpio = pdata->max_gpios;

        platform_set_drvdata(pdev, rdc321x_gpio_dev);

        /* This might not be, what others (BIOS, bootloader, etc.)
           wrote to these registers before, but it's a good guess. Still
           better than just using 0xffffffff. */
        err = pci_read_config_dword(rdc321x_gpio_dev->sb_pdev,
                                        rdc321x_gpio_dev->reg1_data_base,
                                        &rdc321x_gpio_dev->data_reg[0]);
        if (err)
                return pcibios_err_to_errno(err);

        err = pci_read_config_dword(rdc321x_gpio_dev->sb_pdev,
                                        rdc321x_gpio_dev->reg2_data_base,
                                        &rdc321x_gpio_dev->data_reg[1]);
        if (err)
                return pcibios_err_to_errno(err);

        dev_info(&pdev->dev, "registering %d GPIOs\n",
                                        rdc321x_gpio_dev->chip.ngpio);
        return devm_gpiochip_add_data(&pdev->dev, &rdc321x_gpio_dev->chip,
                                      rdc321x_gpio_dev);
}

static struct platform_driver rdc321x_gpio_driver = {
        .driver.name    = "rdc321x-gpio",
        .probe          = rdc321x_gpio_probe,
};

module_platform_driver(rdc321x_gpio_driver);

MODULE_AUTHOR("Florian Fainelli <florian@openwrt.org>");
MODULE_DESCRIPTION("RDC321x GPIO driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:rdc321x-gpio");