// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Servergy CTS-1000 Setup
 *
 * Maintained by Ben Collins <ben.c@servergy.com>
 *
 * Copyright 2012 by Servergy, Inc.
 */

#define pr_fmt(fmt) "gpio-halt: " fmt

#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/device.h>
#include <linux/gpio/consumer.h>
#include <linux/module.h>
#include <linux/of_irq.h>
#include <linux/workqueue.h>
#include <linux/reboot.h>
#include <linux/interrupt.h>

#include <asm/machdep.h>

static struct gpio_desc *halt_gpio;
static int halt_irq;

static const struct of_device_id child_match[] = {
        {
                .compatible = "sgy,gpio-halt",
        },
        {},
};

static void gpio_halt_wfn(struct work_struct *work)
{
        /* Likely wont return */
        orderly_poweroff(true);
}
static DECLARE_WORK(gpio_halt_wq, gpio_halt_wfn);

static void __noreturn gpio_halt_cb(void)
{
        pr_info("triggering GPIO.\n");

        /* Probably wont return */
        gpiod_set_value(halt_gpio, 1);

        panic("Halt failed\n");
}

/* This IRQ means someone pressed the power button and it is waiting for us
 * to handle the shutdown/poweroff. */
static irqreturn_t gpio_halt_irq(int irq, void *__data)
{
        struct platform_device *pdev = __data;

        dev_info(&pdev->dev, "scheduling shutdown due to power button IRQ\n");
        schedule_work(&gpio_halt_wq);

        return IRQ_HANDLED;
};

static int __gpio_halt_probe(struct platform_device *pdev,
                             struct device_node *halt_node)
{
        int err;

        halt_gpio = fwnode_gpiod_get_index(of_fwnode_handle(halt_node),
                                           NULL, 0, GPIOD_OUT_LOW, "gpio-halt");
        err = PTR_ERR_OR_ZERO(halt_gpio);
        if (err) {
                dev_err(&pdev->dev, "failed to request halt GPIO: %d\n", err);
                return err;
        }

        /* Now get the IRQ which tells us when the power button is hit */
        halt_irq = irq_of_parse_and_map(halt_node, 0);
        err = request_irq(halt_irq, gpio_halt_irq,
                          IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
                          "gpio-halt", pdev);
        if (err) {
                dev_err(&pdev->dev, "failed to request IRQ %d: %d\n",
                        halt_irq, err);
                gpiod_put(halt_gpio);
                halt_gpio = NULL;
                return err;
        }

        /* Register our halt function */
        ppc_md.halt = gpio_halt_cb;
        pm_power_off = gpio_halt_cb;

        dev_info(&pdev->dev, "registered halt GPIO, irq: %d\n", halt_irq);

        return 0;
}

static int gpio_halt_probe(struct platform_device *pdev)
{
        struct device_node *halt_node;
        int ret;

        if (!pdev->dev.of_node)
                return -ENODEV;

        /* If there's no matching child, this isn't really an error */
        halt_node = of_find_matching_node(pdev->dev.of_node, child_match);
        if (!halt_node)
                return -ENODEV;

        ret = __gpio_halt_probe(pdev, halt_node);
        of_node_put(halt_node);

        return ret;
}

static void gpio_halt_remove(struct platform_device *pdev)
{
        free_irq(halt_irq, pdev);
        cancel_work_sync(&gpio_halt_wq);

        ppc_md.halt = NULL;
        pm_power_off = NULL;

        gpiod_put(halt_gpio);
        halt_gpio = NULL;
}

static const struct of_device_id gpio_halt_match[] = {
        /* We match on the gpio bus itself and scan the children since they
         * wont be matched against us. We know the bus wont match until it
         * has been registered too. */
        {
                .compatible = "fsl,qoriq-gpio",
        },
        {},
};
MODULE_DEVICE_TABLE(of, gpio_halt_match);

static struct platform_driver gpio_halt_driver = {
        .driver = {
                .name           = "gpio-halt",
                .of_match_table = gpio_halt_match,
        },
        .probe          = gpio_halt_probe,
        .remove         = gpio_halt_remove,
};

module_platform_driver(gpio_halt_driver);

MODULE_DESCRIPTION("Driver to support GPIO triggered system halt for Servergy CTS-1000 Systems.");
MODULE_VERSION("1.0");
MODULE_AUTHOR("Ben Collins <ben.c@servergy.com>");
MODULE_LICENSE("GPL");