drivers/input/misc/pcf8574_keypad.c

   1 /*
   2  * Driver for a keypad w/16 buttons connected to a PCF8574 I2C I/O expander
   3  *
   4  * Copyright 2005-2008 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2 or later.
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/init.h>
  11 #include <linux/input.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/i2c.h>
  14 #include <linux/slab.h>
  15 #include <linux/workqueue.h>
  16
  17 #define DRV_NAME "pcf8574_keypad"
  18
  19 static const unsigned char pcf8574_kp_btncode[] = {
  20         [0] = KEY_RESERVED,
  21         [1] = KEY_ENTER,
  22         [2] = KEY_BACKSLASH,
  23         [3] = KEY_0,
  24         [4] = KEY_RIGHTBRACE,
  25         [5] = KEY_C,
  26         [6] = KEY_9,
  27         [7] = KEY_8,
  28         [8] = KEY_7,
  29         [9] = KEY_B,
  30         [10] = KEY_6,
  31         [11] = KEY_5,
  32         [12] = KEY_4,
  33         [13] = KEY_A,
  34         [14] = KEY_3,
  35         [15] = KEY_2,
  36         [16] = KEY_1
  37 };
  38
  39 struct kp_data {
  40         unsigned short btncode[ARRAY_SIZE(pcf8574_kp_btncode)];
  41         struct input_dev *idev;
  42         struct i2c_client *client;
  43         char name[64];
  44         char phys[32];
  45         unsigned char laststate;
  46 };
  47
  48 static short read_state(struct kp_data *lp)
  49 {
  50         unsigned char x, y, a, b;
  51
  52         i2c_smbus_write_byte(lp->client, 240);
  53         x = 0xF & (~(i2c_smbus_read_byte(lp->client) >> 4));
  54
  55         i2c_smbus_write_byte(lp->client, 15);
  56         y = 0xF & (~i2c_smbus_read_byte(lp->client));
  57
  58         for (a = 0; x > 0; a++)
  59                 x = x >> 1;
  60         for (b = 0; y > 0; b++)
  61                 y = y >> 1;
  62
  63         return ((a - 1) * 4) + b;
  64 }
  65
  66 static irqreturn_t pcf8574_kp_irq_handler(int irq, void *dev_id)
  67 {
  68         struct kp_data *lp = dev_id;
  69         unsigned char nextstate = read_state(lp);
  70
  71         if (lp->laststate != nextstate) {
  72                 int key_down = nextstate < ARRAY_SIZE(lp->btncode);
  73                 unsigned short keycode = key_down ?
  74                         lp->btncode[nextstate] : lp->btncode[lp->laststate];
  75
  76                 input_report_key(lp->idev, keycode, key_down);
  77                 input_sync(lp->idev);
  78
  79                 lp->laststate = nextstate;
  80         }
  81
  82         return IRQ_HANDLED;
  83 }
  84
  85 static int pcf8574_kp_probe(struct i2c_client *client, const struct i2c_device_id *id)
  86 {
  87         int i, ret;
  88         struct input_dev *idev;
  89         struct kp_data *lp;
  90
  91         if (i2c_smbus_write_byte(client, 240) < 0) {
  92                 dev_err(&client->dev, "probe: write fail\n");
  93                 return -ENODEV;
  94         }
  95
  96         lp = kzalloc(sizeof(*lp), GFP_KERNEL);
  97         if (!lp)
  98                 return -ENOMEM;
  99
 100         idev = input_allocate_device();
 101         if (!idev) {
 102                 dev_err(&client->dev, "Can't allocate input device\n");
 103                 ret = -ENOMEM;
 104                 goto fail_allocate;
 105         }
 106
 107         lp->idev = idev;
 108         lp->client = client;
 109
 110         idev->evbit[0] = BIT_MASK(EV_KEY);
 111         idev->keycode = lp->btncode;
 112         idev->keycodesize = sizeof(lp->btncode[0]);
 113         idev->keycodemax = ARRAY_SIZE(lp->btncode);
 114
 115         for (i = 0; i < ARRAY_SIZE(pcf8574_kp_btncode); i++) {
 116                 lp->btncode[i] = pcf8574_kp_btncode[i];
 117                 __set_bit(lp->btncode[i] & KEY_MAX, idev->keybit);
 118         }
 119
 120         sprintf(lp->name, DRV_NAME);
 121         sprintf(lp->phys, "kp_data/input0");
 122
 123         idev->name = lp->name;
 124         idev->phys = lp->phys;
 125         idev->id.bustype = BUS_I2C;
 126         idev->id.vendor = 0x0001;
 127         idev->id.product = 0x0001;
 128         idev->id.version = 0x0100;
 129
 130         lp->laststate = read_state(lp);
 131
 132         ret = request_threaded_irq(client->irq, NULL, pcf8574_kp_irq_handler,
 133                                    IRQF_TRIGGER_LOW | IRQF_ONESHOT,
 134                                    DRV_NAME, lp);
 135         if (ret) {
 136                 dev_err(&client->dev, "IRQ %d is not free\n", client->irq);
 137                 goto fail_free_device;
 138         }
 139
 140         ret = input_register_device(idev);
 141         if (ret) {
 142                 dev_err(&client->dev, "input_register_device() failed\n");
 143                 goto fail_free_irq;
 144         }
 145
 146         i2c_set_clientdata(client, lp);
 147         return 0;
 148
 149  fail_free_irq:
 150         free_irq(client->irq, lp);
 151  fail_free_device:
 152         input_free_device(idev);
 153  fail_allocate:
 154         kfree(lp);
 155
 156         return ret;
 157 }
 158
 159 static int pcf8574_kp_remove(struct i2c_client *client)
 160 {
 161         struct kp_data *lp = i2c_get_clientdata(client);
 162
 163         free_irq(client->irq, lp);
 164
 165         input_unregister_device(lp->idev);
 166         kfree(lp);
 167
 168         return 0;
 169 }
 170
 171 #ifdef CONFIG_PM
 172 static int pcf8574_kp_resume(struct device *dev)
 173 {
 174         struct i2c_client *client = to_i2c_client(dev);
 175
 176         enable_irq(client->irq);
 177
 178         return 0;
 179 }
 180
 181 static int pcf8574_kp_suspend(struct device *dev)
 182 {
 183         struct i2c_client *client = to_i2c_client(dev);
 184
 185         disable_irq(client->irq);
 186
 187         return 0;
 188 }
 189
 190 static const struct dev_pm_ops pcf8574_kp_pm_ops = {
 191         .suspend        = pcf8574_kp_suspend,
 192         .resume         = pcf8574_kp_resume,
 193 };
 194
 195 #else
 196 # define pcf8574_kp_resume  NULL
 197 # define pcf8574_kp_suspend NULL
 198 #endif
 199
 200 static const struct i2c_device_id pcf8574_kp_id[] = {
 201         { DRV_NAME, 0 },
 202         { }
 203 };
 204 MODULE_DEVICE_TABLE(i2c, pcf8574_kp_id);
 205
 206 static struct i2c_driver pcf8574_kp_driver = {
 207         .driver = {
 208                 .name  = DRV_NAME,
 209                 .owner = THIS_MODULE,
 210 #ifdef CONFIG_PM
 211                 .pm = &pcf8574_kp_pm_ops,
 212 #endif
 213         },
 214         .probe    = pcf8574_kp_probe,
 215         .remove   = pcf8574_kp_remove,
 216         .id_table = pcf8574_kp_id,
 217 };
 218
 219 module_i2c_driver(pcf8574_kp_driver);
 220
 221 MODULE_AUTHOR("Michael Hennerich");
 222 MODULE_DESCRIPTION("Keypad input driver for 16 keys connected to PCF8574");
 223 MODULE_LICENSE("GPL");