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Linux/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                 .owner = THIS_MODULE,
137         },
138         .probe  = mfld_pb_probe,
139         .remove = mfld_pb_remove,
140 };
141 
142 module_platform_driver(mfld_pb_driver);
143 
144 MODULE_AUTHOR("Hong Liu <hong.liu@intel.com>");
145 MODULE_DESCRIPTION("Intel Medfield Power Button Driver");
146 MODULE_LICENSE("GPL v2");
147 MODULE_ALIAS("platform:" DRIVER_NAME);
148 

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