drivers/input/touchscreen/egalax_ts_serial.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * EETI Egalax serial touchscreen driver
   4  *
   5  * Copyright (c) 2015 Zoltán Böszörményi <zboszor@pr.hu>
   6  *
   7  * based on the
   8  *
   9  * Hampshire serial touchscreen driver (Copyright (c) 2010 Adam Bennett)
  10  */
  11
  12
  13 #include <linux/errno.h>
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/slab.h>
  17 #include <linux/input.h>
  18 #include <linux/serio.h>
  19
  20 #define DRIVER_DESC     "EETI Egalax serial touchscreen driver"
  21
  22 /*
  23  * Definitions & global arrays.
  24  */
  25
  26 #define EGALAX_FORMAT_MAX_LENGTH        6
  27 #define EGALAX_FORMAT_START_BIT         BIT(7)
  28 #define EGALAX_FORMAT_PRESSURE_BIT      BIT(6)
  29 #define EGALAX_FORMAT_TOUCH_BIT         BIT(0)
  30 #define EGALAX_FORMAT_RESOLUTION_MASK   0x06
  31
  32 #define EGALAX_MIN_XC                   0
  33 #define EGALAX_MAX_XC                   0x4000
  34 #define EGALAX_MIN_YC                   0
  35 #define EGALAX_MAX_YC                   0x4000
  36
  37 /*
  38  * Per-touchscreen data.
  39  */
  40 struct egalax {
  41         struct input_dev *input;
  42         struct serio *serio;
  43         int idx;
  44         u8 data[EGALAX_FORMAT_MAX_LENGTH];
  45         char phys[32];
  46 };
  47
  48 static void egalax_process_data(struct egalax *egalax)
  49 {
  50         struct input_dev *dev = egalax->input;
  51         u8 *data = egalax->data;
  52         u16 x, y;
  53         u8 shift;
  54         u8 mask;
  55
  56         shift = 3 - ((data[0] & EGALAX_FORMAT_RESOLUTION_MASK) >> 1);
  57         mask = 0xff >> (shift + 1);
  58
  59         x = (((u16)(data[1] & mask) << 7) | (data[2] & 0x7f)) << shift;
  60         y = (((u16)(data[3] & mask) << 7) | (data[4] & 0x7f)) << shift;
  61
  62         input_report_key(dev, BTN_TOUCH, data[0] & EGALAX_FORMAT_TOUCH_BIT);
  63         input_report_abs(dev, ABS_X, x);
  64         input_report_abs(dev, ABS_Y, y);
  65         input_sync(dev);
  66 }
  67
  68 static irqreturn_t egalax_interrupt(struct serio *serio,
  69                                     unsigned char data, unsigned int flags)
  70 {
  71         struct egalax *egalax = serio_get_drvdata(serio);
  72         int pkt_len;
  73
  74         egalax->data[egalax->idx++] = data;
  75
  76         if (likely(egalax->data[0] & EGALAX_FORMAT_START_BIT)) {
  77                 pkt_len = egalax->data[0] & EGALAX_FORMAT_PRESSURE_BIT ? 6 : 5;
  78                 if (pkt_len == egalax->idx) {
  79                         egalax_process_data(egalax);
  80                         egalax->idx = 0;
  81                 }
  82         } else {
  83                 dev_dbg(&serio->dev, "unknown/unsynchronized data: %x\n",
  84                         egalax->data[0]);
  85                 egalax->idx = 0;
  86         }
  87
  88         return IRQ_HANDLED;
  89 }
  90
  91 /*
  92  * egalax_connect() is the routine that is called when someone adds a
  93  * new serio device that supports egalax protocol and registers it as
  94  * an input device. This is usually accomplished using inputattach.
  95  */
  96 static int egalax_connect(struct serio *serio, struct serio_driver *drv)
  97 {
  98         struct egalax *egalax;
  99         struct input_dev *input_dev;
 100         int error;
 101
 102         egalax = kzalloc(sizeof(*egalax), GFP_KERNEL);
 103         input_dev = input_allocate_device();
 104         if (!egalax || !input_dev) {
 105                 error = -ENOMEM;
 106                 goto err_free_mem;
 107         }
 108
 109         egalax->serio = serio;
 110         egalax->input = input_dev;
 111         snprintf(egalax->phys, sizeof(egalax->phys),
 112                  "%s/input0", serio->phys);
 113
 114         input_dev->name = "EETI eGalaxTouch Serial TouchScreen";
 115         input_dev->phys = egalax->phys;
 116         input_dev->id.bustype = BUS_RS232;
 117         input_dev->id.vendor = SERIO_EGALAX;
 118         input_dev->id.product = 0;
 119         input_dev->id.version = 0x0001;
 120         input_dev->dev.parent = &serio->dev;
 121
 122         input_set_capability(input_dev, EV_KEY, BTN_TOUCH);
 123         input_set_abs_params(input_dev, ABS_X,
 124                              EGALAX_MIN_XC, EGALAX_MAX_XC, 0, 0);
 125         input_set_abs_params(input_dev, ABS_Y,
 126                              EGALAX_MIN_YC, EGALAX_MAX_YC, 0, 0);
 127
 128         serio_set_drvdata(serio, egalax);
 129
 130         error = serio_open(serio, drv);
 131         if (error)
 132                 goto err_reset_drvdata;
 133
 134         error = input_register_device(input_dev);
 135         if (error)
 136                 goto err_close_serio;
 137
 138         return 0;
 139
 140 err_close_serio:
 141         serio_close(serio);
 142 err_reset_drvdata:
 143         serio_set_drvdata(serio, NULL);
 144 err_free_mem:
 145         input_free_device(input_dev);
 146         kfree(egalax);
 147         return error;
 148 }
 149
 150 static void egalax_disconnect(struct serio *serio)
 151 {
 152         struct egalax *egalax = serio_get_drvdata(serio);
 153
 154         serio_close(serio);
 155         serio_set_drvdata(serio, NULL);
 156         input_unregister_device(egalax->input);
 157         kfree(egalax);
 158 }
 159
 160 /*
 161  * The serio driver structure.
 162  */
 163
 164 static const struct serio_device_id egalax_serio_ids[] = {
 165         {
 166                 .type   = SERIO_RS232,
 167                 .proto  = SERIO_EGALAX,
 168                 .id     = SERIO_ANY,
 169                 .extra  = SERIO_ANY,
 170         },
 171         { 0 }
 172 };
 173
 174 MODULE_DEVICE_TABLE(serio, egalax_serio_ids);
 175
 176 static struct serio_driver egalax_drv = {
 177         .driver         = {
 178                 .name   = "egalax",
 179         },
 180         .description    = DRIVER_DESC,
 181         .id_table       = egalax_serio_ids,
 182         .interrupt      = egalax_interrupt,
 183         .connect        = egalax_connect,
 184         .disconnect     = egalax_disconnect,
 185 };
 186 module_serio_driver(egalax_drv);
 187
 188 MODULE_AUTHOR("Zoltán Böszörményi <zboszor@pr.hu>");
 189 MODULE_DESCRIPTION(DRIVER_DESC);
 190 MODULE_LICENSE("GPL v2");