intel_mid_powerbtn.c

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/*
 * Power button driver for Medfield.
 *
 * Copyright (C) 2010 Intel Corp
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 */

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

static irqreturn_t mfld_pb_isr(int irq, void *dev_id)
{
    struct input_dev *input = dev_id;
    int ret;
    u8 pbstat;

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

    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,
                   !(pbstat & MSIC_PB_LEVEL));
        input_sync(input);
    }

    return IRQ_HANDLED;
}

static int __devinit mfld_pb_probe(struct platform_device *pdev)
{
    struct input_dev *input;
    int irq = platform_get_irq(pdev, 0);
    int error;

    if (irq < 0)
        return -EINVAL;

    input = input_allocate_device();
    if (!input) {
        dev_err(&pdev->dev, "Input device allocation error\n");
        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);

    error = request_threaded_irq(irq, NULL, mfld_pb_isr, IRQF_NO_SUSPEND,
            DRIVER_NAME, input);
    if (error) {
        dev_err(&pdev->dev, "Unable to request irq %d for mfld power"
                "button\n", irq);
        goto err_free_input;
    }

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

    platform_set_drvdata(pdev, input);

    /*
     * 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 = intel_msic_reg_update(INTEL_MSIC_IRQLVL1MSK, 0, MSIC_PWRBTNM);
    if (error) {
        dev_err(&pdev->dev, "Unable to clear power button interrupt, "
                "error: %d\n", error);
        goto err_free_irq;
    }

    return 0;

err_free_irq:
    free_irq(irq, input);
err_free_input:
    input_free_device(input);
    return error;
}

static int __devexit mfld_pb_remove(struct platform_device *pdev)
{
    struct input_dev *input = platform_get_drvdata(pdev);
    int irq = platform_get_irq(pdev, 0);

    free_irq(irq, input);
    input_unregister_device(input);
    platform_set_drvdata(pdev, NULL);

    return 0;
}

static struct platform_driver mfld_pb_driver = {
    .driver = {
        .name = DRIVER_NAME,
        .owner = THIS_MODULE,
    },
    .probe  = mfld_pb_probe,
    .remove = __devexit_p(mfld_pb_remove),
};

module_platform_driver(mfld_pb_driver);

MODULE_AUTHOR("Hong Liu <[email protected]>");
MODULE_DESCRIPTION("Intel Medfield Power Button Driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:" DRIVER_NAME);