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  1/*
  2 * Power button driver for Medfield.
  3 *
  4 * Copyright (C) 2010 Intel Corp
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License as published by
  8 * the Free Software Foundation; version 2 of the License.
  9 *
 10 * This program is distributed in the hope that it will be useful, but
 11 * WITHOUT ANY WARRANTY; without even the implied warranty of
 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 13 * General Public License for more details.
 14 *
 15 * You should have received a copy of the GNU General Public License along
 16 * with this program; if not, write to the Free Software Foundation, Inc.,
 17 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 18 */
 19
 20#include <linux/module.h>
 21#include <linux/init.h>
 22#include <linux/interrupt.h>
 23#include <linux/slab.h>
 24#include <linux/platform_device.h>
 25#include <linux/input.h>
 26#include <linux/mfd/intel_msic.h>
 27
 28#define DRIVER_NAME "msic_power_btn"
 29
 30#define MSIC_PB_LEVEL	(1 << 3) /* 1 - release, 0 - press */
 31
 32/*
 33 * MSIC document ti_datasheet defines the 1st bit reg 0x21 is used to mask
 34 * power button interrupt
 35 */
 36#define MSIC_PWRBTNM    (1 << 0)
 37
 38static irqreturn_t mfld_pb_isr(int irq, void *dev_id)
 39{
 40	struct input_dev *input = dev_id;
 41	int ret;
 42	u8 pbstat;
 43
 44	ret = intel_msic_reg_read(INTEL_MSIC_PBSTATUS, &pbstat);
 45	dev_dbg(input->dev.parent, "PB_INT status= %d\n", pbstat);
 46
 47	if (ret < 0) {
 48		dev_err(input->dev.parent, "Read error %d while reading"
 49			       " MSIC_PB_STATUS\n", ret);
 50	} else {
 51		input_event(input, EV_KEY, KEY_POWER,
 52			       !(pbstat & MSIC_PB_LEVEL));
 53		input_sync(input);
 54	}
 55
 56	return IRQ_HANDLED;
 57}
 58
 59static int mfld_pb_probe(struct platform_device *pdev)
 60{
 61	struct input_dev *input;
 62	int irq = platform_get_irq(pdev, 0);
 63	int error;
 64
 65	if (irq < 0)
 66		return -EINVAL;
 67
 68	input = input_allocate_device();
 69	if (!input)
 70		return -ENOMEM;
 71
 72	input->name = pdev->name;
 73	input->phys = "power-button/input0";
 74	input->id.bustype = BUS_HOST;
 75	input->dev.parent = &pdev->dev;
 76
 77	input_set_capability(input, EV_KEY, KEY_POWER);
 78
 79	error = request_threaded_irq(irq, NULL, mfld_pb_isr, IRQF_NO_SUSPEND,
 80			DRIVER_NAME, input);
 81	if (error) {
 82		dev_err(&pdev->dev, "Unable to request irq %d for mfld power"
 83				"button\n", irq);
 84		goto err_free_input;
 85	}
 86
 87	error = input_register_device(input);
 88	if (error) {
 89		dev_err(&pdev->dev, "Unable to register input dev, error "
 90				"%d\n", error);
 91		goto err_free_irq;
 92	}
 93
 94	platform_set_drvdata(pdev, input);
 95
 96	/*
 97	 * SCU firmware might send power button interrupts to IA core before
 98	 * kernel boots and doesn't get EOI from IA core. The first bit of
 99	 * MSIC reg 0x21 is kept masked, and SCU firmware doesn't send new
100	 * power interrupt to Android kernel. Unmask the bit when probing
101	 * power button in kernel.
102	 * There is a very narrow race between irq handler and power button
103	 * initialization. The race happens rarely. So we needn't worry
104	 * about it.
105	 */
106	error = intel_msic_reg_update(INTEL_MSIC_IRQLVL1MSK, 0, MSIC_PWRBTNM);
107	if (error) {
108		dev_err(&pdev->dev, "Unable to clear power button interrupt, "
109				"error: %d\n", error);
110		goto err_free_irq;
111	}
112
113	return 0;
114
115err_free_irq:
116	free_irq(irq, input);
117err_free_input:
118	input_free_device(input);
119	return error;
120}
121
122static int mfld_pb_remove(struct platform_device *pdev)
123{
124	struct input_dev *input = platform_get_drvdata(pdev);
125	int irq = platform_get_irq(pdev, 0);
126
127	free_irq(irq, input);
128	input_unregister_device(input);
129
130	return 0;
131}
132
133static struct platform_driver mfld_pb_driver = {
134	.driver = {
135		.name = DRIVER_NAME,
136		.owner = THIS_MODULE,
137	},
138	.probe	= mfld_pb_probe,
139	.remove	= mfld_pb_remove,
140};
141
142module_platform_driver(mfld_pb_driver);
143
144MODULE_AUTHOR("Hong Liu <hong.liu@intel.com>");
145MODULE_DESCRIPTION("Intel Medfield Power Button Driver");
146MODULE_LICENSE("GPL v2");
147MODULE_ALIAS("platform:" DRIVER_NAME);