drivers/input/touchscreen/exc3000.c

   1 /*
   2  * Driver for I2C connected EETI EXC3000 multiple touch controller
   3  *
   4  * Copyright (C) 2017 Ahmet Inan <inan@distec.de>
   5  *
   6  * minimal implementation based on egalax_ts.c and egalax_i2c.c
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/bitops.h>
  14 #include <linux/device.h>
  15 #include <linux/i2c.h>
  16 #include <linux/input.h>
  17 #include <linux/input/mt.h>
  18 #include <linux/input/touchscreen.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/module.h>
  21 #include <linux/of.h>
  22 #include <linux/timer.h>
  23 #include <asm/unaligned.h>
  24
  25 #define EXC3000_NUM_SLOTS               10
  26 #define EXC3000_SLOTS_PER_FRAME         5
  27 #define EXC3000_LEN_FRAME               66
  28 #define EXC3000_LEN_POINT               10
  29 #define EXC3000_MT_EVENT                6
  30 #define EXC3000_TIMEOUT_MS              100
  31
  32 struct exc3000_data {
  33         struct i2c_client *client;
  34         struct input_dev *input;
  35         struct touchscreen_properties prop;
  36         struct timer_list timer;
  37         u8 buf[2 * EXC3000_LEN_FRAME];
  38 };
  39
  40 static void exc3000_report_slots(struct input_dev *input,
  41                                  struct touchscreen_properties *prop,
  42                                  const u8 *buf, int num)
  43 {
  44         for (; num--; buf += EXC3000_LEN_POINT) {
  45                 if (buf[0] & BIT(0)) {
  46                         input_mt_slot(input, buf[1]);
  47                         input_mt_report_slot_state(input, MT_TOOL_FINGER, true);
  48                         touchscreen_report_pos(input, prop,
  49                                                get_unaligned_le16(buf + 2),
  50                                                get_unaligned_le16(buf + 4),
  51                                                true);
  52                 }
  53         }
  54 }
  55
  56 static void exc3000_timer(struct timer_list *t)
  57 {
  58         struct exc3000_data *data = from_timer(data, t, timer);
  59
  60         input_mt_sync_frame(data->input);
  61         input_sync(data->input);
  62 }
  63
  64 static int exc3000_read_frame(struct i2c_client *client, u8 *buf)
  65 {
  66         int ret;
  67
  68         ret = i2c_master_send(client, "'", 2);
  69         if (ret < 0)
  70                 return ret;
  71
  72         if (ret != 2)
  73                 return -EIO;
  74
  75         ret = i2c_master_recv(client, buf, EXC3000_LEN_FRAME);
  76         if (ret < 0)
  77                 return ret;
  78
  79         if (ret != EXC3000_LEN_FRAME)
  80                 return -EIO;
  81
  82         if (get_unaligned_le16(buf) != EXC3000_LEN_FRAME ||
  83                         buf[2] != EXC3000_MT_EVENT)
  84                 return -EINVAL;
  85
  86         return 0;
  87 }
  88
  89 static int exc3000_read_data(struct i2c_client *client,
  90                              u8 *buf, int *n_slots)
  91 {
  92         int error;
  93
  94         error = exc3000_read_frame(client, buf);
  95         if (error)
  96                 return error;
  97
  98         *n_slots = buf[3];
  99         if (!*n_slots || *n_slots > EXC3000_NUM_SLOTS)
 100                 return -EINVAL;
 101
 102         if (*n_slots > EXC3000_SLOTS_PER_FRAME) {
 103                 /* Read 2nd frame to get the rest of the contacts. */
 104                 error = exc3000_read_frame(client, buf + EXC3000_LEN_FRAME);
 105                 if (error)
 106                         return error;
 107
 108                 /* 2nd chunk must have number of contacts set to 0. */
 109                 if (buf[EXC3000_LEN_FRAME + 3] != 0)
 110                         return -EINVAL;
 111         }
 112
 113         return 0;
 114 }
 115
 116 static irqreturn_t exc3000_interrupt(int irq, void *dev_id)
 117 {
 118         struct exc3000_data *data = dev_id;
 119         struct input_dev *input = data->input;
 120         u8 *buf = data->buf;
 121         int slots, total_slots;
 122         int error;
 123
 124         error = exc3000_read_data(data->client, buf, &total_slots);
 125         if (error) {
 126                 /* Schedule a timer to release "stuck" contacts */
 127                 mod_timer(&data->timer,
 128                           jiffies + msecs_to_jiffies(EXC3000_TIMEOUT_MS));
 129                 goto out;
 130         }
 131
 132         /*
 133          * We read full state successfully, no contacts will be "stuck".
 134          */
 135         del_timer_sync(&data->timer);
 136
 137         while (total_slots > 0) {
 138                 slots = min(total_slots, EXC3000_SLOTS_PER_FRAME);
 139                 exc3000_report_slots(input, &data->prop, buf + 4, slots);
 140                 total_slots -= slots;
 141                 buf += EXC3000_LEN_FRAME;
 142         }
 143
 144         input_mt_sync_frame(input);
 145         input_sync(input);
 146
 147 out:
 148         return IRQ_HANDLED;
 149 }
 150
 151 static int exc3000_probe(struct i2c_client *client,
 152                          const struct i2c_device_id *id)
 153 {
 154         struct exc3000_data *data;
 155         struct input_dev *input;
 156         int error;
 157
 158         data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
 159         if (!data)
 160                 return -ENOMEM;
 161
 162         data->client = client;
 163         timer_setup(&data->timer, exc3000_timer, 0);
 164
 165         input = devm_input_allocate_device(&client->dev);
 166         if (!input)
 167                 return -ENOMEM;
 168
 169         data->input = input;
 170
 171         input->name = "EETI EXC3000 Touch Screen";
 172         input->id.bustype = BUS_I2C;
 173
 174         input_set_abs_params(input, ABS_MT_POSITION_X, 0, 4095, 0, 0);
 175         input_set_abs_params(input, ABS_MT_POSITION_Y, 0, 4095, 0, 0);
 176         touchscreen_parse_properties(input, true, &data->prop);
 177
 178         error = input_mt_init_slots(input, EXC3000_NUM_SLOTS,
 179                                     INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
 180         if (error)
 181                 return error;
 182
 183         error = input_register_device(input);
 184         if (error)
 185                 return error;
 186
 187         error = devm_request_threaded_irq(&client->dev, client->irq,
 188                                           NULL, exc3000_interrupt, IRQF_ONESHOT,
 189                                           client->name, data);
 190         if (error)
 191                 return error;
 192
 193         return 0;
 194 }
 195
 196 static const struct i2c_device_id exc3000_id[] = {
 197         { "exc3000", 0 },
 198         { }
 199 };
 200 MODULE_DEVICE_TABLE(i2c, exc3000_id);
 201
 202 #ifdef CONFIG_OF
 203 static const struct of_device_id exc3000_of_match[] = {
 204         { .compatible = "eeti,exc3000" },
 205         { }
 206 };
 207 MODULE_DEVICE_TABLE(of, exc3000_of_match);
 208 #endif
 209
 210 static struct i2c_driver exc3000_driver = {
 211         .driver = {
 212                 .name   = "exc3000",
 213                 .of_match_table = of_match_ptr(exc3000_of_match),
 214         },
 215         .id_table       = exc3000_id,
 216         .probe          = exc3000_probe,
 217 };
 218
 219 module_i2c_driver(exc3000_driver);
 220
 221 MODULE_AUTHOR("Ahmet Inan <inan@distec.de>");
 222 MODULE_DESCRIPTION("I2C connected EETI EXC3000 multiple touch controller driver");
 223 MODULE_LICENSE("GPL v2");