/*
 * Power button driver for Intel MID platforms.
 *
 * Copyright (C) 2010,2017 Intel Corp
 *
 * Author: Hong Liu <hong.liu@intel.com>
 * Author: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 */

#include <linux/init.h>
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/mfd/intel_msic.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pm_wakeirq.h>
#include <linux/slab.h>

#include <asm/cpu_device_id.h>
#include <asm/intel-family.h>
#include <asm/intel_scu_ipc.h>

#define DRIVER_NAME "msic_power_btn"

#define MSIC_PB_LEVEL   (1 << 3) /* 1 - release, 0 - press */

/*
 * MSIC document ti_datasheet defines the 1st bit reg 0x21 is used to mask
 * power button interrupt
 */
#define MSIC_PWRBTNM    (1 << 0)

/* Intel Tangier */
#define BCOVE_PB_LEVEL          (1 << 4)        /* 1 - release, 0 - press */

/* Basin Cove PMIC */
#define BCOVE_PBIRQ             0x02
#define BCOVE_IRQLVL1MSK        0x0c
#define BCOVE_PBIRQMASK         0x0d
#define BCOVE_PBSTATUS          0x27

struct mid_pb_ddata {
        struct device *dev;
        int irq;
        struct input_dev *input;
        unsigned short mirqlvl1_addr;
        unsigned short pbstat_addr;
        u8 pbstat_mask;
        int (*setup)(struct mid_pb_ddata *ddata);
};

static int mid_pbstat(struct mid_pb_ddata *ddata, int *value)
{
        struct input_dev *input = ddata->input;
        int ret;
        u8 pbstat;

        ret = intel_scu_ipc_ioread8(ddata->pbstat_addr, &pbstat);
        if (ret)
                return ret;

        dev_dbg(input->dev.parent, "PB_INT status= %d\n", pbstat);

        *value = !(pbstat & ddata->pbstat_mask);
        return 0;
}

static int mid_irq_ack(struct mid_pb_ddata *ddata)
{
        return intel_scu_ipc_update_register(ddata->mirqlvl1_addr, 0, MSIC_PWRBTNM);
}

static int mrfld_setup(struct mid_pb_ddata *ddata)
{
        /* Unmask the PBIRQ and MPBIRQ on Tangier */
        intel_scu_ipc_update_register(BCOVE_PBIRQ, 0, MSIC_PWRBTNM);
        intel_scu_ipc_update_register(BCOVE_PBIRQMASK, 0, MSIC_PWRBTNM);

        return 0;
}

static irqreturn_t mid_pb_isr(int irq, void *dev_id)
{
        struct mid_pb_ddata *ddata = dev_id;
        struct input_dev *input = ddata->input;
        int value = 0;
        int ret;

        ret = mid_pbstat(ddata, &value);
        if (ret < 0) {
                dev_err(input->dev.parent,
                        "Read error %d while reading MSIC_PB_STATUS\n", ret);
        } else {
                input_event(input, EV_KEY, KEY_POWER, value);
                input_sync(input);
        }

        mid_irq_ack(ddata);
        return IRQ_HANDLED;
}

static const struct mid_pb_ddata mfld_ddata = {
        .mirqlvl1_addr  = INTEL_MSIC_IRQLVL1MSK,
        .pbstat_addr    = INTEL_MSIC_PBSTATUS,
        .pbstat_mask    = MSIC_PB_LEVEL,
};

static const struct mid_pb_ddata mrfld_ddata = {
        .mirqlvl1_addr  = BCOVE_IRQLVL1MSK,
        .pbstat_addr    = BCOVE_PBSTATUS,
        .pbstat_mask    = BCOVE_PB_LEVEL,
        .setup  = mrfld_setup,
};

#define ICPU(model, ddata)      \
        { X86_VENDOR_INTEL, 6, model, X86_FEATURE_ANY, (kernel_ulong_t)&ddata }

static const struct x86_cpu_id mid_pb_cpu_ids[] = {
        ICPU(INTEL_FAM6_ATOM_SALTWELL_MID,              mfld_ddata),
        ICPU(INTEL_FAM6_ATOM_SILVERMONT_MID,    mrfld_ddata),
        {}
};

static int mid_pb_probe(struct platform_device *pdev)
{
        const struct x86_cpu_id *id;
        struct mid_pb_ddata *ddata;
        struct input_dev *input;
        int irq = platform_get_irq(pdev, 0);
        int error;

        id = x86_match_cpu(mid_pb_cpu_ids);
        if (!id)
                return -ENODEV;

        if (irq < 0) {
                dev_err(&pdev->dev, "Failed to get IRQ: %d\n", irq);
                return irq;
        }

        input = devm_input_allocate_device(&pdev->dev);
        if (!input)
                return -ENOMEM;

        input->name = pdev->name;
        input->phys = "power-button/input0";
        input->id.bustype = BUS_HOST;
        input->dev.parent = &pdev->dev;

        input_set_capability(input, EV_KEY, KEY_POWER);

        ddata = (struct mid_pb_ddata *)id->driver_data;
        if (!ddata)
                return -ENODATA;

        ddata->dev = &pdev->dev;
        ddata->irq = irq;
        ddata->input = input;

        if (ddata->setup) {
                error = ddata->setup(ddata);
                if (error)
                        return error;
        }

        error = devm_request_threaded_irq(&pdev->dev, irq, NULL, mid_pb_isr,
                                          IRQF_ONESHOT, DRIVER_NAME, ddata);
        if (error) {
                dev_err(&pdev->dev,
                        "Unable to request irq %d for MID power button\n", irq);
                return error;
        }

        error = input_register_device(input);
        if (error) {
                dev_err(&pdev->dev,
                        "Unable to register input dev, error %d\n", error);
                return error;
        }

        platform_set_drvdata(pdev, ddata);

        /*
         * SCU firmware might send power button interrupts to IA core before
         * kernel boots and doesn't get EOI from IA core. The first bit of
         * MSIC reg 0x21 is kept masked, and SCU firmware doesn't send new
         * power interrupt to Android kernel. Unmask the bit when probing
         * power button in kernel.
         * There is a very narrow race between irq handler and power button
         * initialization. The race happens rarely. So we needn't worry
         * about it.
         */
        error = mid_irq_ack(ddata);
        if (error) {
                dev_err(&pdev->dev,
                        "Unable to clear power button interrupt, error: %d\n",
                        error);
                return error;
        }

        device_init_wakeup(&pdev->dev, true);
        dev_pm_set_wake_irq(&pdev->dev, irq);

        return 0;
}

static int mid_pb_remove(struct platform_device *pdev)
{
        dev_pm_clear_wake_irq(&pdev->dev);
        device_init_wakeup(&pdev->dev, false);

        return 0;
}

static struct platform_driver mid_pb_driver = {
        .driver = {
                .name = DRIVER_NAME,
        },
        .probe  = mid_pb_probe,
        .remove = mid_pb_remove,
};

module_platform_driver(mid_pb_driver);

MODULE_AUTHOR("Hong Liu <hong.liu@intel.com>");
MODULE_DESCRIPTION("Intel MID Power Button Driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:" DRIVER_NAME);