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