linux/drivers/input/touchscreen/eeti_ts.c
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   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 <asm/unaligned.h>
  25
  26struct 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
  44static 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
  66static 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
  87static 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
 116static 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
 134static 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
 145static 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
 154static 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
 161static int eeti_ts_probe(struct i2c_client *client,
 162                         const struct i2c_device_id *idp)
 163{
 164        struct device *dev = &client->dev;
 165        struct eeti_ts *eeti;
 166        struct input_dev *input;
 167        int error;
 168
 169        /*
 170         * In contrast to what's described in the datasheet, there seems
 171         * to be no way of probing the presence of that device using I2C
 172         * commands. So we need to blindly believe it is there, and wait
 173         * for interrupts to occur.
 174         */
 175
 176        eeti = devm_kzalloc(dev, sizeof(*eeti), GFP_KERNEL);
 177        if (!eeti) {
 178                dev_err(dev, "failed to allocate driver data\n");
 179                return -ENOMEM;
 180        }
 181
 182        mutex_init(&eeti->mutex);
 183
 184        input = devm_input_allocate_device(dev);
 185        if (!input) {
 186                dev_err(dev, "Failed to allocate input device.\n");
 187                return -ENOMEM;
 188        }
 189
 190        input_set_capability(input, EV_KEY, BTN_TOUCH);
 191
 192        input_set_abs_params(input, ABS_X, 0, EETI_MAXVAL, 0, 0);
 193        input_set_abs_params(input, ABS_Y, 0, EETI_MAXVAL, 0, 0);
 194        input_set_abs_params(input, ABS_PRESSURE, 0, 0xff, 0, 0);
 195
 196        touchscreen_parse_properties(input, false, &eeti->props);
 197
 198        input->name = client->name;
 199        input->id.bustype = BUS_I2C;
 200        input->open = eeti_ts_open;
 201        input->close = eeti_ts_close;
 202
 203        eeti->client = client;
 204        eeti->input = input;
 205
 206        eeti->attn_gpio = devm_gpiod_get_optional(dev, "attn", GPIOD_IN);
 207        if (IS_ERR(eeti->attn_gpio))
 208                return PTR_ERR(eeti->attn_gpio);
 209
 210        i2c_set_clientdata(client, eeti);
 211        input_set_drvdata(input, eeti);
 212
 213        error = devm_request_threaded_irq(dev, client->irq,
 214                                          NULL, eeti_ts_isr,
 215                                          IRQF_ONESHOT,
 216                                          client->name, eeti);
 217        if (error) {
 218                dev_err(dev, "Unable to request touchscreen IRQ: %d\n",
 219                        error);
 220                return error;
 221        }
 222
 223        /*
 224         * Disable the device for now. It will be enabled once the
 225         * input device is opened.
 226         */
 227        eeti_ts_stop(eeti);
 228
 229        error = input_register_device(input);
 230        if (error)
 231                return error;
 232
 233        return 0;
 234}
 235
 236static int __maybe_unused eeti_ts_suspend(struct device *dev)
 237{
 238        struct i2c_client *client = to_i2c_client(dev);
 239        struct eeti_ts *eeti = i2c_get_clientdata(client);
 240        struct input_dev *input_dev = eeti->input;
 241
 242        mutex_lock(&input_dev->mutex);
 243
 244        if (input_dev->users)
 245                eeti_ts_stop(eeti);
 246
 247        mutex_unlock(&input_dev->mutex);
 248
 249        if (device_may_wakeup(&client->dev))
 250                enable_irq_wake(client->irq);
 251
 252        return 0;
 253}
 254
 255static int __maybe_unused eeti_ts_resume(struct device *dev)
 256{
 257        struct i2c_client *client = to_i2c_client(dev);
 258        struct eeti_ts *eeti = i2c_get_clientdata(client);
 259        struct input_dev *input_dev = eeti->input;
 260
 261        if (device_may_wakeup(&client->dev))
 262                disable_irq_wake(client->irq);
 263
 264        mutex_lock(&input_dev->mutex);
 265
 266        if (input_dev->users)
 267                eeti_ts_start(eeti);
 268
 269        mutex_unlock(&input_dev->mutex);
 270
 271        return 0;
 272}
 273
 274static SIMPLE_DEV_PM_OPS(eeti_ts_pm, eeti_ts_suspend, eeti_ts_resume);
 275
 276static const struct i2c_device_id eeti_ts_id[] = {
 277        { "eeti_ts", 0 },
 278        { }
 279};
 280MODULE_DEVICE_TABLE(i2c, eeti_ts_id);
 281
 282#ifdef CONFIG_OF
 283static const struct of_device_id of_eeti_ts_match[] = {
 284        { .compatible = "eeti,exc3000-i2c", },
 285        { }
 286};
 287#endif
 288
 289static struct i2c_driver eeti_ts_driver = {
 290        .driver = {
 291                .name = "eeti_ts",
 292                .pm = &eeti_ts_pm,
 293                .of_match_table = of_match_ptr(of_eeti_ts_match),
 294        },
 295        .probe = eeti_ts_probe,
 296        .id_table = eeti_ts_id,
 297};
 298
 299module_i2c_driver(eeti_ts_driver);
 300
 301MODULE_DESCRIPTION("EETI Touchscreen driver");
 302MODULE_AUTHOR("Daniel Mack <daniel@zonque.org>");
 303MODULE_LICENSE("GPL");
 304