drivers/platform/x86/intel_mid_powerbtn.c

   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
  38 static 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
  59 static 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
 115 err_free_irq:
 116         free_irq(irq, input);
 117 err_free_input:
 118         input_free_device(input);
 119         return error;
 120 }
 121
 122 static 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
 133 static struct platform_driver mfld_pb_driver = {
 134         .driver = {
 135                 .name = DRIVER_NAME,
 136         },
 137         .probe  = mfld_pb_probe,
 138         .remove = mfld_pb_remove,
 139 };
 140
 141 module_platform_driver(mfld_pb_driver);
 142
 143 MODULE_AUTHOR("Hong Liu <hong.liu@intel.com>");
 144 MODULE_DESCRIPTION("Intel Medfield Power Button Driver");
 145 MODULE_LICENSE("GPL v2");
 146 MODULE_ALIAS("platform:" DRIVER_NAME);