// SPDX-License-Identifier: GPL-2.0
/*
 * Gemini power management controller
 * Copyright (C) 2017 Linus Walleij <linus.walleij@linaro.org>
 *
 * Inspired by code from the SL3516 board support by Jason Lee
 * Inspired by code from Janos Laube <janos.dev@gmail.com>
 */
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/pm.h>
#include <linux/bitops.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/reboot.h>

#define GEMINI_PWC_ID           0x00010500
#define GEMINI_PWC_IDREG        0x00
#define GEMINI_PWC_CTRLREG      0x04
#define GEMINI_PWC_STATREG      0x08

#define GEMINI_CTRL_SHUTDOWN    BIT(0)
#define GEMINI_CTRL_ENABLE      BIT(1)
#define GEMINI_CTRL_IRQ_CLR     BIT(2)

#define GEMINI_STAT_CIR         BIT(4)
#define GEMINI_STAT_RTC         BIT(5)
#define GEMINI_STAT_POWERBUTTON BIT(6)

struct gemini_powercon {
        struct device           *dev;
        void __iomem            *base;
};

static irqreturn_t gemini_powerbutton_interrupt(int irq, void *data)
{
        struct gemini_powercon *gpw = data;
        u32 val;

        /* ACK the IRQ */
        val = readl(gpw->base + GEMINI_PWC_CTRLREG);
        val |= GEMINI_CTRL_IRQ_CLR;
        writel(val, gpw->base + GEMINI_PWC_CTRLREG);

        val = readl(gpw->base + GEMINI_PWC_STATREG);
        val &= 0x70U;
        switch (val) {
        case GEMINI_STAT_CIR:
                /*
                 * We do not yet have a driver for the infrared
                 * controller so it can cause spurious poweroff
                 * events. Ignore those for now.
                 */
                dev_info(gpw->dev, "infrared poweroff - ignored\n");
                break;
        case GEMINI_STAT_RTC:
                dev_info(gpw->dev, "RTC poweroff\n");
                orderly_poweroff(true);
                break;
        case GEMINI_STAT_POWERBUTTON:
                dev_info(gpw->dev, "poweroff button pressed\n");
                orderly_poweroff(true);
                break;
        default:
                dev_info(gpw->dev, "other power management IRQ\n");
                break;
        }

        return IRQ_HANDLED;
}

static int gemini_poweroff(struct sys_off_data *data)
{
        struct gemini_powercon *gpw = data->cb_data;
        u32 val;

        dev_crit(gpw->dev, "Gemini power off\n");
        val = readl(gpw->base + GEMINI_PWC_CTRLREG);
        val |= GEMINI_CTRL_ENABLE | GEMINI_CTRL_IRQ_CLR;
        writel(val, gpw->base + GEMINI_PWC_CTRLREG);

        val &= ~GEMINI_CTRL_ENABLE;
        val |= GEMINI_CTRL_SHUTDOWN;
        writel(val, gpw->base + GEMINI_PWC_CTRLREG);

        return NOTIFY_DONE;
}

static int gemini_poweroff_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct gemini_powercon *gpw;
        u32 val;
        int irq;
        int ret;

        gpw = devm_kzalloc(dev, sizeof(*gpw), GFP_KERNEL);
        if (!gpw)
                return -ENOMEM;

        gpw->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(gpw->base))
                return PTR_ERR(gpw->base);

        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return irq;

        gpw->dev = dev;

        val = readl(gpw->base + GEMINI_PWC_IDREG);
        val &= 0xFFFFFF00U;
        if (val != GEMINI_PWC_ID) {
                dev_err(dev, "wrong power controller ID: %08x\n",
                        val);
                return -ENODEV;
        }

        /*
         * Enable the power controller. This is crucial on Gemini
         * systems: if this is not done, pressing the power button
         * will result in unconditional poweroff without any warning.
         * This makes the kernel handle the poweroff.
         */
        val = readl(gpw->base + GEMINI_PWC_CTRLREG);
        val |= GEMINI_CTRL_ENABLE;
        writel(val, gpw->base + GEMINI_PWC_CTRLREG);

        /* Clear the IRQ */
        val = readl(gpw->base + GEMINI_PWC_CTRLREG);
        val |= GEMINI_CTRL_IRQ_CLR;
        writel(val, gpw->base + GEMINI_PWC_CTRLREG);

        /* Wait for this to clear */
        val = readl(gpw->base + GEMINI_PWC_STATREG);
        while (val & 0x70U)
                val = readl(gpw->base + GEMINI_PWC_STATREG);

        /* Clear the IRQ again */
        val = readl(gpw->base + GEMINI_PWC_CTRLREG);
        val |= GEMINI_CTRL_IRQ_CLR;
        writel(val, gpw->base + GEMINI_PWC_CTRLREG);

        ret = devm_request_irq(dev, irq, gemini_powerbutton_interrupt, 0,
                               "poweroff", gpw);
        if (ret)
                return ret;

        ret = devm_register_sys_off_handler(dev, SYS_OFF_MODE_POWER_OFF,
                                            SYS_OFF_PRIO_DEFAULT,
                                            gemini_poweroff, gpw);
        if (ret)
                return ret;

        dev_info(dev, "Gemini poweroff driver registered\n");

        return 0;
}

static const struct of_device_id gemini_poweroff_of_match[] = {
        {
                .compatible = "cortina,gemini-power-controller",
        },
        {}
};

static struct platform_driver gemini_poweroff_driver = {
        .probe = gemini_poweroff_probe,
        .driver = {
                .name = "gemini-poweroff",
                .of_match_table = gemini_poweroff_of_match,
        },
};
builtin_platform_driver(gemini_poweroff_driver);