drivers/input/mouse/gpio_mouse.c

   1 /*
   2  * Driver for simulating a mouse on GPIO lines.
   3  *
   4  * Copyright (C) 2007 Atmel Corporation
   5  * Copyright (C) 2017 Linus Walleij <linus.walleij@linaro.org>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/input-polldev.h>
  15 #include <linux/gpio/consumer.h>
  16 #include <linux/property.h>
  17 #include <linux/of.h>
  18
  19 /**
  20  * struct gpio_mouse
  21  * @scan_ms: the scan interval in milliseconds.
  22  * @up: GPIO line for up value.
  23  * @down: GPIO line for down value.
  24  * @left: GPIO line for left value.
  25  * @right: GPIO line for right value.
  26  * @bleft: GPIO line for left button.
  27  * @bmiddle: GPIO line for middle button.
  28  * @bright: GPIO line for right button.
  29  *
  30  * This struct must be added to the platform_device in the board code.
  31  * It is used by the gpio_mouse driver to setup GPIO lines and to
  32  * calculate mouse movement.
  33  */
  34 struct gpio_mouse {
  35         u32 scan_ms;
  36         struct gpio_desc *up;
  37         struct gpio_desc *down;
  38         struct gpio_desc *left;
  39         struct gpio_desc *right;
  40         struct gpio_desc *bleft;
  41         struct gpio_desc *bmiddle;
  42         struct gpio_desc *bright;
  43 };
  44
  45 /*
  46  * Timer function which is run every scan_ms ms when the device is opened.
  47  * The dev input variable is set to the the input_dev pointer.
  48  */
  49 static void gpio_mouse_scan(struct input_polled_dev *dev)
  50 {
  51         struct gpio_mouse *gpio = dev->private;
  52         struct input_dev *input = dev->input;
  53         int x, y;
  54
  55         if (gpio->bleft)
  56                 input_report_key(input, BTN_LEFT,
  57                                  gpiod_get_value(gpio->bleft));
  58         if (gpio->bmiddle)
  59                 input_report_key(input, BTN_MIDDLE,
  60                                  gpiod_get_value(gpio->bmiddle));
  61         if (gpio->bright)
  62                 input_report_key(input, BTN_RIGHT,
  63                                  gpiod_get_value(gpio->bright));
  64
  65         x = gpiod_get_value(gpio->right) - gpiod_get_value(gpio->left);
  66         y = gpiod_get_value(gpio->down) - gpiod_get_value(gpio->up);
  67
  68         input_report_rel(input, REL_X, x);
  69         input_report_rel(input, REL_Y, y);
  70         input_sync(input);
  71 }
  72
  73 static int gpio_mouse_probe(struct platform_device *pdev)
  74 {
  75         struct device *dev = &pdev->dev;
  76         struct gpio_mouse *gmouse;
  77         struct input_polled_dev *input_poll;
  78         struct input_dev *input;
  79         int ret;
  80
  81         gmouse = devm_kzalloc(dev, sizeof(*gmouse), GFP_KERNEL);
  82         if (!gmouse)
  83                 return -ENOMEM;
  84
  85         /* Assign some default scanning time */
  86         ret = device_property_read_u32(dev, "scan-interval-ms",
  87                                        &gmouse->scan_ms);
  88         if (ret || gmouse->scan_ms == 0) {
  89                 dev_warn(dev, "invalid scan time, set to 50 ms\n");
  90                 gmouse->scan_ms = 50;
  91         }
  92
  93         gmouse->up = devm_gpiod_get(dev, "up", GPIOD_IN);
  94         if (IS_ERR(gmouse->up))
  95                 return PTR_ERR(gmouse->up);
  96         gmouse->down = devm_gpiod_get(dev, "down", GPIOD_IN);
  97         if (IS_ERR(gmouse->down))
  98                 return PTR_ERR(gmouse->down);
  99         gmouse->left = devm_gpiod_get(dev, "left", GPIOD_IN);
 100         if (IS_ERR(gmouse->left))
 101                 return PTR_ERR(gmouse->left);
 102         gmouse->right = devm_gpiod_get(dev, "right", GPIOD_IN);
 103         if (IS_ERR(gmouse->right))
 104                 return PTR_ERR(gmouse->right);
 105
 106         gmouse->bleft = devm_gpiod_get_optional(dev, "button-left", GPIOD_IN);
 107         if (IS_ERR(gmouse->bleft))
 108                 return PTR_ERR(gmouse->bleft);
 109         gmouse->bmiddle = devm_gpiod_get_optional(dev, "button-middle",
 110                                                   GPIOD_IN);
 111         if (IS_ERR(gmouse->bmiddle))
 112                 return PTR_ERR(gmouse->bmiddle);
 113         gmouse->bright = devm_gpiod_get_optional(dev, "button-right",
 114                                                  GPIOD_IN);
 115         if (IS_ERR(gmouse->bright))
 116                 return PTR_ERR(gmouse->bright);
 117
 118         input_poll = devm_input_allocate_polled_device(dev);
 119         if (!input_poll) {
 120                 dev_err(dev, "not enough memory for input device\n");
 121                 return -ENOMEM;
 122         }
 123
 124         platform_set_drvdata(pdev, input_poll);
 125
 126         /* set input-polldev handlers */
 127         input_poll->private = gmouse;
 128         input_poll->poll = gpio_mouse_scan;
 129         input_poll->poll_interval = gmouse->scan_ms;
 130
 131         input = input_poll->input;
 132         input->name = pdev->name;
 133         input->id.bustype = BUS_HOST;
 134         input->dev.parent = &pdev->dev;
 135
 136         input_set_capability(input, EV_REL, REL_X);
 137         input_set_capability(input, EV_REL, REL_Y);
 138         if (gmouse->bleft)
 139                 input_set_capability(input, EV_KEY, BTN_LEFT);
 140         if (gmouse->bmiddle)
 141                 input_set_capability(input, EV_KEY, BTN_MIDDLE);
 142         if (gmouse->bright)
 143                 input_set_capability(input, EV_KEY, BTN_RIGHT);
 144
 145         ret = input_register_polled_device(input_poll);
 146         if (ret) {
 147                 dev_err(dev, "could not register input device\n");
 148                 return ret;
 149         }
 150
 151         dev_dbg(dev, "%d ms scan time, buttons: %s%s%s\n",
 152                 gmouse->scan_ms,
 153                 gmouse->bleft ? "" : "left ",
 154                 gmouse->bmiddle ? "" : "middle ",
 155                 gmouse->bright ? "" : "right");
 156
 157         return 0;
 158 }
 159
 160 static const struct of_device_id gpio_mouse_of_match[] = {
 161         { .compatible = "gpio-mouse", },
 162         { },
 163 };
 164 MODULE_DEVICE_TABLE(of, gpio_mouse_of_match);
 165
 166 static struct platform_driver gpio_mouse_device_driver = {
 167         .probe          = gpio_mouse_probe,
 168         .driver         = {
 169                 .name   = "gpio_mouse",
 170                 .of_match_table = gpio_mouse_of_match,
 171         }
 172 };
 173 module_platform_driver(gpio_mouse_device_driver);
 174
 175 MODULE_AUTHOR("Hans-Christian Egtvedt <egtvedt@samfundet.no>");
 176 MODULE_DESCRIPTION("GPIO mouse driver");
 177 MODULE_LICENSE("GPL");
 178 MODULE_ALIAS("platform:gpio_mouse"); /* work with hotplug and coldplug */