1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * ADC generic resistive touchscreen (GRTS) 4 * This is a generic input driver that connects to an ADC 5 * given the channels in device tree, and reports events to the input 6 * subsystem. 7 * 8 * Copyright (C) 2017,2018 Microchip Technology, 9 * Author: Eugen Hristev <eugen.hristev@microchip.com> 10 * 11 */ 12 #include <linux/input.h> 13 #include <linux/input/touchscreen.h> 14 #include <linux/iio/consumer.h> 15 #include <linux/iio/iio.h> 16 #include <linux/module.h> 17 #include <linux/of.h> 18 #include <linux/of_device.h> 19 #include <linux/platform_device.h> 20 21 #define DRIVER_NAME "resistive-adc-touch" 22 #define GRTS_DEFAULT_PRESSURE_MIN 50000 23 #define GRTS_MAX_POS_MASK GENMASK(11, 0) 24 25 /** 26 * grts_state - generic resistive touch screen information struct 27 * @pressure_min: number representing the minimum for the pressure 28 * @pressure: are we getting pressure info or not 29 * @iio_chans: list of channels acquired 30 * @iio_cb: iio_callback buffer for the data 31 * @input: the input device structure that we register 32 * @prop: touchscreen properties struct 33 */ 34 struct grts_state { 35 u32 pressure_min; 36 bool pressure; 37 struct iio_channel *iio_chans; 38 struct iio_cb_buffer *iio_cb; 39 struct input_dev *input; 40 struct touchscreen_properties prop; 41 }; 42 43 static int grts_cb(const void *data, void *private) 44 { 45 const u16 *touch_info = data; 46 struct grts_state *st = private; 47 unsigned int x, y, press = 0x0; 48 49 /* channel data coming in buffer in the order below */ 50 x = touch_info[0]; 51 y = touch_info[1]; 52 if (st->pressure) 53 press = touch_info[2]; 54 55 if ((!x && !y) || (st->pressure && (press < st->pressure_min))) { 56 /* report end of touch */ 57 input_report_key(st->input, BTN_TOUCH, 0); 58 input_sync(st->input); 59 return 0; 60 } 61 62 /* report proper touch to subsystem*/ 63 touchscreen_report_pos(st->input, &st->prop, x, y, false); 64 if (st->pressure) 65 input_report_abs(st->input, ABS_PRESSURE, press); 66 input_report_key(st->input, BTN_TOUCH, 1); 67 input_sync(st->input); 68 69 return 0; 70 } 71 72 static int grts_open(struct input_dev *dev) 73 { 74 int error; 75 struct grts_state *st = input_get_drvdata(dev); 76 77 error = iio_channel_start_all_cb(st->iio_cb); 78 if (error) { 79 dev_err(dev->dev.parent, "failed to start callback buffer.\n"); 80 return error; 81 } 82 return 0; 83 } 84 85 static void grts_close(struct input_dev *dev) 86 { 87 struct grts_state *st = input_get_drvdata(dev); 88 89 iio_channel_stop_all_cb(st->iio_cb); 90 } 91 92 static void grts_disable(void *data) 93 { 94 iio_channel_release_all_cb(data); 95 } 96 97 static int grts_probe(struct platform_device *pdev) 98 { 99 struct grts_state *st; 100 struct input_dev *input; 101 struct device *dev = &pdev->dev; 102 struct iio_channel *chan; 103 int error; 104 105 st = devm_kzalloc(dev, sizeof(struct grts_state), GFP_KERNEL); 106 if (!st) 107 return -ENOMEM; 108 109 /* get the channels from IIO device */ 110 st->iio_chans = devm_iio_channel_get_all(dev); 111 if (IS_ERR(st->iio_chans)) { 112 error = PTR_ERR(st->iio_chans); 113 if (error != -EPROBE_DEFER) 114 dev_err(dev, "can't get iio channels.\n"); 115 return error; 116 } 117 118 chan = &st->iio_chans[0]; 119 st->pressure = false; 120 while (chan && chan->indio_dev) { 121 if (!strcmp(chan->channel->datasheet_name, "pressure")) 122 st->pressure = true; 123 chan++; 124 } 125 126 if (st->pressure) { 127 error = device_property_read_u32(dev, 128 "touchscreen-min-pressure", 129 &st->pressure_min); 130 if (error) { 131 dev_dbg(dev, "can't get touchscreen-min-pressure property.\n"); 132 st->pressure_min = GRTS_DEFAULT_PRESSURE_MIN; 133 } 134 } 135 136 input = devm_input_allocate_device(dev); 137 if (!input) { 138 dev_err(dev, "failed to allocate input device.\n"); 139 return -ENOMEM; 140 } 141 142 input->name = DRIVER_NAME; 143 input->id.bustype = BUS_HOST; 144 input->open = grts_open; 145 input->close = grts_close; 146 147 input_set_abs_params(input, ABS_X, 0, GRTS_MAX_POS_MASK - 1, 0, 0); 148 input_set_abs_params(input, ABS_Y, 0, GRTS_MAX_POS_MASK - 1, 0, 0); 149 if (st->pressure) 150 input_set_abs_params(input, ABS_PRESSURE, st->pressure_min, 151 0xffff, 0, 0); 152 153 input_set_capability(input, EV_KEY, BTN_TOUCH); 154 155 /* parse optional device tree properties */ 156 touchscreen_parse_properties(input, false, &st->prop); 157 158 st->input = input; 159 input_set_drvdata(input, st); 160 161 error = input_register_device(input); 162 if (error) { 163 dev_err(dev, "failed to register input device."); 164 return error; 165 } 166 167 st->iio_cb = iio_channel_get_all_cb(dev, grts_cb, st); 168 if (IS_ERR(st->iio_cb)) { 169 dev_err(dev, "failed to allocate callback buffer.\n"); 170 return PTR_ERR(st->iio_cb); 171 } 172 173 error = devm_add_action_or_reset(dev, grts_disable, st->iio_cb); 174 if (error) { 175 dev_err(dev, "failed to add disable action.\n"); 176 return error; 177 } 178 179 return 0; 180 } 181 182 static const struct of_device_id grts_of_match[] = { 183 { 184 .compatible = "resistive-adc-touch", 185 }, { 186 /* sentinel */ 187 }, 188 }; 189 190 MODULE_DEVICE_TABLE(of, grts_of_match); 191 192 static struct platform_driver grts_driver = { 193 .probe = grts_probe, 194 .driver = { 195 .name = DRIVER_NAME, 196 .of_match_table = of_match_ptr(grts_of_match), 197 }, 198 }; 199 200 module_platform_driver(grts_driver); 201 202 MODULE_AUTHOR("Eugen Hristev <eugen.hristev@microchip.com>"); 203 MODULE_DESCRIPTION("Generic ADC Resistive Touch Driver"); 204 MODULE_LICENSE("GPL v2"); 205