drivers/input/touchscreen/eeti_ts.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Touch Screen driver for EETI's I2C connected touch screen panels
   4  *   Copyright (c) 2009,2018 Daniel Mack <daniel@zonque.org>
   5  *
   6  * See EETI's software guide for the protocol specification:
   7  *   http://home.eeti.com.tw/documentation.html
   8  *
   9  * Based on migor_ts.c
  10  *   Copyright (c) 2008 Magnus Damm
  11  *   Copyright (c) 2007 Ujjwal Pande <ujjwal@kenati.com>
  12  */
  13
  14 #include <linux/module.h>
  15 #include <linux/kernel.h>
  16 #include <linux/input.h>
  17 #include <linux/input/touchscreen.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/i2c.h>
  20 #include <linux/timer.h>
  21 #include <linux/gpio/consumer.h>
  22 #include <linux/of.h>
  23 #include <linux/slab.h>
  24 #include <linux/unaligned.h>
  25
  26 struct eeti_ts {
  27         struct i2c_client *client;
  28         struct input_dev *input;
  29         struct gpio_desc *attn_gpio;
  30         struct touchscreen_properties props;
  31         struct mutex mutex;
  32         bool running;
  33 };
  34
  35 #define EETI_TS_BITDEPTH        (11)
  36 #define EETI_MAXVAL             ((1 << (EETI_TS_BITDEPTH + 1)) - 1)
  37
  38 #define REPORT_BIT_PRESSED      BIT(0)
  39 #define REPORT_BIT_AD0          BIT(1)
  40 #define REPORT_BIT_AD1          BIT(2)
  41 #define REPORT_BIT_HAS_PRESSURE BIT(6)
  42 #define REPORT_RES_BITS(v)      (((v) >> 1) + EETI_TS_BITDEPTH)
  43
  44 static void eeti_ts_report_event(struct eeti_ts *eeti, u8 *buf)
  45 {
  46         unsigned int res;
  47         u16 x, y;
  48
  49         res = REPORT_RES_BITS(buf[0] & (REPORT_BIT_AD0 | REPORT_BIT_AD1));
  50
  51         x = get_unaligned_be16(&buf[1]);
  52         y = get_unaligned_be16(&buf[3]);
  53
  54         /* fix the range to 11 bits */
  55         x >>= res - EETI_TS_BITDEPTH;
  56         y >>= res - EETI_TS_BITDEPTH;
  57
  58         if (buf[0] & REPORT_BIT_HAS_PRESSURE)
  59                 input_report_abs(eeti->input, ABS_PRESSURE, buf[5]);
  60
  61         touchscreen_report_pos(eeti->input, &eeti->props, x, y, false);
  62         input_report_key(eeti->input, BTN_TOUCH, buf[0] & REPORT_BIT_PRESSED);
  63         input_sync(eeti->input);
  64 }
  65
  66 static int eeti_ts_read(struct eeti_ts *eeti)
  67 {
  68         int len, error;
  69         char buf[6];
  70
  71         len = i2c_master_recv(eeti->client, buf, sizeof(buf));
  72         if (len != sizeof(buf)) {
  73                 error = len < 0 ? len : -EIO;
  74                 dev_err(&eeti->client->dev,
  75                         "failed to read touchscreen data: %d\n",
  76                         error);
  77                 return error;
  78         }
  79
  80         /* Motion packet */
  81         if (buf[0] & 0x80)
  82                 eeti_ts_report_event(eeti, buf);
  83
  84         return 0;
  85 }
  86
  87 static irqreturn_t eeti_ts_isr(int irq, void *dev_id)
  88 {
  89         struct eeti_ts *eeti = dev_id;
  90         int error;
  91
  92         mutex_lock(&eeti->mutex);
  93
  94         do {
  95                 /*
  96                  * If we have attention GPIO, trust it. Otherwise we'll read
  97                  * once and exit. We assume that in this case we are using
  98                  * level triggered interrupt and it will get raised again
  99                  * if/when there is more data.
 100                  */
 101                 if (eeti->attn_gpio &&
 102                     !gpiod_get_value_cansleep(eeti->attn_gpio)) {
 103                         break;
 104                 }
 105
 106                 error = eeti_ts_read(eeti);
 107                 if (error)
 108                         break;
 109
 110         } while (eeti->running && eeti->attn_gpio);
 111
 112         mutex_unlock(&eeti->mutex);
 113         return IRQ_HANDLED;
 114 }
 115
 116 static void eeti_ts_start(struct eeti_ts *eeti)
 117 {
 118         mutex_lock(&eeti->mutex);
 119
 120         eeti->running = true;
 121         enable_irq(eeti->client->irq);
 122
 123         /*
 124          * Kick the controller in case we are using edge interrupt and
 125          * we missed our edge while interrupt was disabled. We expect
 126          * the attention GPIO to be wired in this case.
 127          */
 128         if (eeti->attn_gpio && gpiod_get_value_cansleep(eeti->attn_gpio))
 129                 eeti_ts_read(eeti);
 130
 131         mutex_unlock(&eeti->mutex);
 132 }
 133
 134 static void eeti_ts_stop(struct eeti_ts *eeti)
 135 {
 136         /*
 137          * Not locking here, just setting a flag and expect that the
 138          * interrupt thread will notice the flag eventually.
 139          */
 140         eeti->running = false;
 141         wmb();
 142         disable_irq(eeti->client->irq);
 143 }
 144
 145 static int eeti_ts_open(struct input_dev *dev)
 146 {
 147         struct eeti_ts *eeti = input_get_drvdata(dev);
 148
 149         eeti_ts_start(eeti);
 150
 151         return 0;
 152 }
 153
 154 static void eeti_ts_close(struct input_dev *dev)
 155 {
 156         struct eeti_ts *eeti = input_get_drvdata(dev);
 157
 158         eeti_ts_stop(eeti);
 159 }
 160
 161 static int eeti_ts_probe(struct i2c_client *client)
 162 {
 163         struct device *dev = &client->dev;
 164         struct eeti_ts *eeti;
 165         struct input_dev *input;
 166         int error;
 167
 168         /*
 169          * In contrast to what's described in the datasheet, there seems
 170          * to be no way of probing the presence of that device using I2C
 171          * commands. So we need to blindly believe it is there, and wait
 172          * for interrupts to occur.
 173          */
 174
 175         eeti = devm_kzalloc(dev, sizeof(*eeti), GFP_KERNEL);
 176         if (!eeti) {
 177                 dev_err(dev, "failed to allocate driver data\n");
 178                 return -ENOMEM;
 179         }
 180
 181         mutex_init(&eeti->mutex);
 182
 183         input = devm_input_allocate_device(dev);
 184         if (!input) {
 185                 dev_err(dev, "Failed to allocate input device.\n");
 186                 return -ENOMEM;
 187         }
 188
 189         input_set_capability(input, EV_KEY, BTN_TOUCH);
 190
 191         input_set_abs_params(input, ABS_X, 0, EETI_MAXVAL, 0, 0);
 192         input_set_abs_params(input, ABS_Y, 0, EETI_MAXVAL, 0, 0);
 193         input_set_abs_params(input, ABS_PRESSURE, 0, 0xff, 0, 0);
 194
 195         touchscreen_parse_properties(input, false, &eeti->props);
 196
 197         input->name = client->name;
 198         input->id.bustype = BUS_I2C;
 199         input->open = eeti_ts_open;
 200         input->close = eeti_ts_close;
 201
 202         eeti->client = client;
 203         eeti->input = input;
 204
 205         eeti->attn_gpio = devm_gpiod_get_optional(dev, "attn", GPIOD_IN);
 206         if (IS_ERR(eeti->attn_gpio))
 207                 return PTR_ERR(eeti->attn_gpio);
 208
 209         i2c_set_clientdata(client, eeti);
 210         input_set_drvdata(input, eeti);
 211
 212         error = devm_request_threaded_irq(dev, client->irq,
 213                                           NULL, eeti_ts_isr,
 214                                           IRQF_ONESHOT,
 215                                           client->name, eeti);
 216         if (error) {
 217                 dev_err(dev, "Unable to request touchscreen IRQ: %d\n",
 218                         error);
 219                 return error;
 220         }
 221
 222         /*
 223          * Disable the device for now. It will be enabled once the
 224          * input device is opened.
 225          */
 226         eeti_ts_stop(eeti);
 227
 228         error = input_register_device(input);
 229         if (error)
 230                 return error;
 231
 232         return 0;
 233 }
 234
 235 static int eeti_ts_suspend(struct device *dev)
 236 {
 237         struct i2c_client *client = to_i2c_client(dev);
 238         struct eeti_ts *eeti = i2c_get_clientdata(client);
 239         struct input_dev *input_dev = eeti->input;
 240
 241         mutex_lock(&input_dev->mutex);
 242
 243         if (input_device_enabled(input_dev))
 244                 eeti_ts_stop(eeti);
 245
 246         mutex_unlock(&input_dev->mutex);
 247
 248         if (device_may_wakeup(&client->dev))
 249                 enable_irq_wake(client->irq);
 250
 251         return 0;
 252 }
 253
 254 static int eeti_ts_resume(struct device *dev)
 255 {
 256         struct i2c_client *client = to_i2c_client(dev);
 257         struct eeti_ts *eeti = i2c_get_clientdata(client);
 258         struct input_dev *input_dev = eeti->input;
 259
 260         if (device_may_wakeup(&client->dev))
 261                 disable_irq_wake(client->irq);
 262
 263         mutex_lock(&input_dev->mutex);
 264
 265         if (input_device_enabled(input_dev))
 266                 eeti_ts_start(eeti);
 267
 268         mutex_unlock(&input_dev->mutex);
 269
 270         return 0;
 271 }
 272
 273 static DEFINE_SIMPLE_DEV_PM_OPS(eeti_ts_pm, eeti_ts_suspend, eeti_ts_resume);
 274
 275 static const struct i2c_device_id eeti_ts_id[] = {
 276         { "eeti_ts" },
 277         { }
 278 };
 279 MODULE_DEVICE_TABLE(i2c, eeti_ts_id);
 280
 281 #ifdef CONFIG_OF
 282 static const struct of_device_id of_eeti_ts_match[] = {
 283         { .compatible = "eeti,exc3000-i2c", },
 284         { }
 285 };
 286 #endif
 287
 288 static struct i2c_driver eeti_ts_driver = {
 289         .driver = {
 290                 .name = "eeti_ts",
 291                 .pm = pm_sleep_ptr(&eeti_ts_pm),
 292                 .of_match_table = of_match_ptr(of_eeti_ts_match),
 293         },
 294         .probe = eeti_ts_probe,
 295         .id_table = eeti_ts_id,
 296 };
 297
 298 module_i2c_driver(eeti_ts_driver);
 299
 300 MODULE_DESCRIPTION("EETI Touchscreen driver");
 301 MODULE_AUTHOR("Daniel Mack <daniel@zonque.org>");
 302 MODULE_LICENSE("GPL");