drivers/input/misc/pcf8574_keypad.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Driver for a keypad w/16 buttons connected to a PCF8574 I2C I/O expander
   4  *
   5  * Copyright 2005-2008 Analog Devices Inc.
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/input.h>
  10 #include <linux/interrupt.h>
  11 #include <linux/i2c.h>
  12 #include <linux/slab.h>
  13 #include <linux/workqueue.h>
  14
  15 #define DRV_NAME "pcf8574_keypad"
  16
  17 static const unsigned char pcf8574_kp_btncode[] = {
  18         [0] = KEY_RESERVED,
  19         [1] = KEY_ENTER,
  20         [2] = KEY_BACKSLASH,
  21         [3] = KEY_0,
  22         [4] = KEY_RIGHTBRACE,
  23         [5] = KEY_C,
  24         [6] = KEY_9,
  25         [7] = KEY_8,
  26         [8] = KEY_7,
  27         [9] = KEY_B,
  28         [10] = KEY_6,
  29         [11] = KEY_5,
  30         [12] = KEY_4,
  31         [13] = KEY_A,
  32         [14] = KEY_3,
  33         [15] = KEY_2,
  34         [16] = KEY_1
  35 };
  36
  37 struct kp_data {
  38         unsigned short btncode[ARRAY_SIZE(pcf8574_kp_btncode)];
  39         struct input_dev *idev;
  40         struct i2c_client *client;
  41         char name[64];
  42         char phys[32];
  43         unsigned char laststate;
  44 };
  45
  46 static short read_state(struct kp_data *lp)
  47 {
  48         unsigned char x, y, a, b;
  49
  50         i2c_smbus_write_byte(lp->client, 240);
  51         x = 0xF & (~(i2c_smbus_read_byte(lp->client) >> 4));
  52
  53         i2c_smbus_write_byte(lp->client, 15);
  54         y = 0xF & (~i2c_smbus_read_byte(lp->client));
  55
  56         for (a = 0; x > 0; a++)
  57                 x = x >> 1;
  58         for (b = 0; y > 0; b++)
  59                 y = y >> 1;
  60
  61         return ((a - 1) * 4) + b;
  62 }
  63
  64 static irqreturn_t pcf8574_kp_irq_handler(int irq, void *dev_id)
  65 {
  66         struct kp_data *lp = dev_id;
  67         unsigned char nextstate = read_state(lp);
  68
  69         if (lp->laststate != nextstate) {
  70                 int key_down = nextstate < ARRAY_SIZE(lp->btncode);
  71                 unsigned short keycode = key_down ?
  72                         lp->btncode[nextstate] : lp->btncode[lp->laststate];
  73
  74                 input_report_key(lp->idev, keycode, key_down);
  75                 input_sync(lp->idev);
  76
  77                 lp->laststate = nextstate;
  78         }
  79
  80         return IRQ_HANDLED;
  81 }
  82
  83 static int pcf8574_kp_probe(struct i2c_client *client)
  84 {
  85         int i, ret;
  86         struct input_dev *idev;
  87         struct kp_data *lp;
  88
  89         if (i2c_smbus_write_byte(client, 240) < 0) {
  90                 dev_err(&client->dev, "probe: write fail\n");
  91                 return -ENODEV;
  92         }
  93
  94         lp = kzalloc(sizeof(*lp), GFP_KERNEL);
  95         if (!lp)
  96                 return -ENOMEM;
  97
  98         idev = input_allocate_device();
  99         if (!idev) {
 100                 dev_err(&client->dev, "Can't allocate input device\n");
 101                 ret = -ENOMEM;
 102                 goto fail_allocate;
 103         }
 104
 105         lp->idev = idev;
 106         lp->client = client;
 107
 108         idev->evbit[0] = BIT_MASK(EV_KEY);
 109         idev->keycode = lp->btncode;
 110         idev->keycodesize = sizeof(lp->btncode[0]);
 111         idev->keycodemax = ARRAY_SIZE(lp->btncode);
 112
 113         for (i = 0; i < ARRAY_SIZE(pcf8574_kp_btncode); i++) {
 114                 if (lp->btncode[i] <= KEY_MAX) {
 115                         lp->btncode[i] = pcf8574_kp_btncode[i];
 116                         __set_bit(lp->btncode[i], idev->keybit);
 117                 }
 118         }
 119         __clear_bit(KEY_RESERVED, idev->keybit);
 120
 121         sprintf(lp->name, DRV_NAME);
 122         sprintf(lp->phys, "kp_data/input0");
 123
 124         idev->name = lp->name;
 125         idev->phys = lp->phys;
 126         idev->id.bustype = BUS_I2C;
 127         idev->id.vendor = 0x0001;
 128         idev->id.product = 0x0001;
 129         idev->id.version = 0x0100;
 130
 131         lp->laststate = read_state(lp);
 132
 133         ret = request_threaded_irq(client->irq, NULL, pcf8574_kp_irq_handler,
 134                                    IRQF_TRIGGER_LOW | IRQF_ONESHOT,
 135                                    DRV_NAME, lp);
 136         if (ret) {
 137                 dev_err(&client->dev, "IRQ %d is not free\n", client->irq);
 138                 goto fail_free_device;
 139         }
 140
 141         ret = input_register_device(idev);
 142         if (ret) {
 143                 dev_err(&client->dev, "input_register_device() failed\n");
 144                 goto fail_free_irq;
 145         }
 146
 147         i2c_set_clientdata(client, lp);
 148         return 0;
 149
 150  fail_free_irq:
 151         free_irq(client->irq, lp);
 152  fail_free_device:
 153         input_free_device(idev);
 154  fail_allocate:
 155         kfree(lp);
 156
 157         return ret;
 158 }
 159
 160 static void pcf8574_kp_remove(struct i2c_client *client)
 161 {
 162         struct kp_data *lp = i2c_get_clientdata(client);
 163
 164         free_irq(client->irq, lp);
 165
 166         input_unregister_device(lp->idev);
 167         kfree(lp);
 168 }
 169
 170 static int pcf8574_kp_resume(struct device *dev)
 171 {
 172         struct i2c_client *client = to_i2c_client(dev);
 173
 174         enable_irq(client->irq);
 175
 176         return 0;
 177 }
 178
 179 static int pcf8574_kp_suspend(struct device *dev)
 180 {
 181         struct i2c_client *client = to_i2c_client(dev);
 182
 183         disable_irq(client->irq);
 184
 185         return 0;
 186 }
 187
 188 static DEFINE_SIMPLE_DEV_PM_OPS(pcf8574_kp_pm_ops,
 189                                 pcf8574_kp_suspend, pcf8574_kp_resume);
 190
 191 static const struct i2c_device_id pcf8574_kp_id[] = {
 192         { DRV_NAME, 0 },
 193         { }
 194 };
 195 MODULE_DEVICE_TABLE(i2c, pcf8574_kp_id);
 196
 197 static struct i2c_driver pcf8574_kp_driver = {
 198         .driver = {
 199                 .name  = DRV_NAME,
 200                 .pm = pm_sleep_ptr(&pcf8574_kp_pm_ops),
 201         },
 202         .probe    = pcf8574_kp_probe,
 203         .remove   = pcf8574_kp_remove,
 204         .id_table = pcf8574_kp_id,
 205 };
 206
 207 module_i2c_driver(pcf8574_kp_driver);
 208
 209 MODULE_AUTHOR("Michael Hennerich");
 210 MODULE_DESCRIPTION("Keypad input driver for 16 keys connected to PCF8574");
 211 MODULE_LICENSE("GPL");