// SPDX-License-Identifier: GPL-2.0-only
/*
 * AMD Promontory GPIO driver
 *
 * Copyright (C) 2015 ASMedia Technology Inc.
 * Author: YD Tseng <yd_tseng@asmedia.com.tw>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/gpio/driver.h>
#include <linux/gpio/generic.h>
#include <linux/spinlock.h>
#include <linux/acpi.h>
#include <linux/platform_device.h>

#define PT_TOTAL_GPIO 8
#define PT_TOTAL_GPIO_EX 24

/* PCI-E MMIO register offsets */
#define PT_DIRECTION_REG   0x00
#define PT_INPUTDATA_REG   0x04
#define PT_OUTPUTDATA_REG  0x08
#define PT_CLOCKRATE_REG   0x0C
#define PT_SYNC_REG        0x28

struct pt_gpio_chip {
        struct gpio_generic_chip chip;
        void __iomem             *reg_base;
};

static int pt_gpio_request(struct gpio_chip *gc, unsigned offset)
{
        struct gpio_generic_chip *gen_gc = to_gpio_generic_chip(gc);
        struct pt_gpio_chip *pt_gpio = gpiochip_get_data(gc);
        u32 using_pins;

        dev_dbg(gc->parent, "pt_gpio_request offset=%x\n", offset);

        guard(gpio_generic_lock_irqsave)(gen_gc);

        using_pins = readl(pt_gpio->reg_base + PT_SYNC_REG);
        if (using_pins & BIT(offset)) {
                dev_warn(gc->parent, "PT GPIO pin %x reconfigured\n",
                         offset);
                return -EINVAL;
        }

        writel(using_pins | BIT(offset), pt_gpio->reg_base + PT_SYNC_REG);

        return 0;
}

static void pt_gpio_free(struct gpio_chip *gc, unsigned offset)
{
        struct gpio_generic_chip *gen_gc = to_gpio_generic_chip(gc);
        struct pt_gpio_chip *pt_gpio = gpiochip_get_data(gc);
        u32 using_pins;

        guard(gpio_generic_lock_irqsave)(gen_gc);

        using_pins = readl(pt_gpio->reg_base + PT_SYNC_REG);
        using_pins &= ~BIT(offset);
        writel(using_pins, pt_gpio->reg_base + PT_SYNC_REG);

        dev_dbg(gc->parent, "pt_gpio_free offset=%x\n", offset);
}

static int pt_gpio_probe(struct platform_device *pdev)
{
        struct gpio_generic_chip_config config;
        struct device *dev = &pdev->dev;
        struct pt_gpio_chip *pt_gpio;
        int ret = 0;

        if (!ACPI_COMPANION(dev)) {
                dev_err(dev, "PT GPIO device node not found\n");
                return -ENODEV;
        }

        pt_gpio = devm_kzalloc(dev, sizeof(struct pt_gpio_chip), GFP_KERNEL);
        if (!pt_gpio)
                return -ENOMEM;

        pt_gpio->reg_base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(pt_gpio->reg_base)) {
                dev_err(dev, "Failed to map MMIO resource for PT GPIO.\n");
                return PTR_ERR(pt_gpio->reg_base);
        }

        config = (struct gpio_generic_chip_config) {
                .dev = dev,
                .sz = 4,
                .dat = pt_gpio->reg_base + PT_INPUTDATA_REG,
                .set = pt_gpio->reg_base + PT_OUTPUTDATA_REG,
                .dirout = pt_gpio->reg_base + PT_DIRECTION_REG,
                .flags = GPIO_GENERIC_READ_OUTPUT_REG_SET,
        };

        ret = gpio_generic_chip_init(&pt_gpio->chip, &config);
        if (ret) {
                dev_err(dev, "failed to initialize the generic GPIO chip\n");
                return ret;
        }

        pt_gpio->chip.gc.owner = THIS_MODULE;
        pt_gpio->chip.gc.request = pt_gpio_request;
        pt_gpio->chip.gc.free = pt_gpio_free;
        pt_gpio->chip.gc.ngpio = (uintptr_t)device_get_match_data(dev);

        ret = devm_gpiochip_add_data(dev, &pt_gpio->chip.gc, pt_gpio);
        if (ret) {
                dev_err(dev, "Failed to register GPIO lib\n");
                return ret;
        }

        platform_set_drvdata(pdev, pt_gpio);

        /* initialize register setting */
        writel(0, pt_gpio->reg_base + PT_SYNC_REG);
        writel(0, pt_gpio->reg_base + PT_CLOCKRATE_REG);

        dev_dbg(dev, "PT GPIO driver loaded\n");
        return ret;
}

static const struct acpi_device_id pt_gpio_acpi_match[] = {
        { "AMDF030", PT_TOTAL_GPIO },
        { "AMDIF030", PT_TOTAL_GPIO },
        { "AMDIF031", PT_TOTAL_GPIO_EX },
        { },
};
MODULE_DEVICE_TABLE(acpi, pt_gpio_acpi_match);

static struct platform_driver pt_gpio_driver = {
        .driver = {
                .name = "pt-gpio",
                .acpi_match_table = ACPI_PTR(pt_gpio_acpi_match),
        },
        .probe = pt_gpio_probe,
};

module_platform_driver(pt_gpio_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("YD Tseng <yd_tseng@asmedia.com.tw>");
MODULE_DESCRIPTION("AMD Promontory GPIO Driver");