1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Input driver for resistor ladder connected on ADC 4 * 5 * Copyright (c) 2016 Alexandre Belloni 6 */ 7 8 #include <linux/err.h> 9 #include <linux/iio/consumer.h> 10 #include <linux/iio/types.h> 11 #include <linux/input.h> 12 #include <linux/input-polldev.h> 13 #include <linux/kernel.h> 14 #include <linux/module.h> 15 #include <linux/of.h> 16 #include <linux/platform_device.h> 17 #include <linux/property.h> 18 #include <linux/slab.h> 19 20 struct adc_keys_button { 21 u32 voltage; 22 u32 keycode; 23 }; 24 25 struct adc_keys_state { 26 struct iio_channel *channel; 27 u32 num_keys; 28 u32 last_key; 29 u32 keyup_voltage; 30 const struct adc_keys_button *map; 31 }; 32 33 static void adc_keys_poll(struct input_polled_dev *dev) 34 { 35 struct adc_keys_state *st = dev->private; 36 int i, value, ret; 37 u32 diff, closest = 0xffffffff; 38 int keycode = 0; 39 40 ret = iio_read_channel_processed(st->channel, &value); 41 if (unlikely(ret < 0)) { 42 /* Forcibly release key if any was pressed */ 43 value = st->keyup_voltage; 44 } else { 45 for (i = 0; i < st->num_keys; i++) { 46 diff = abs(st->map[i].voltage - value); 47 if (diff < closest) { 48 closest = diff; 49 keycode = st->map[i].keycode; 50 } 51 } 52 } 53 54 if (abs(st->keyup_voltage - value) < closest) 55 keycode = 0; 56 57 if (st->last_key && st->last_key != keycode) 58 input_report_key(dev->input, st->last_key, 0); 59 60 if (keycode) 61 input_report_key(dev->input, keycode, 1); 62 63 input_sync(dev->input); 64 st->last_key = keycode; 65 } 66 67 static int adc_keys_load_keymap(struct device *dev, struct adc_keys_state *st) 68 { 69 struct adc_keys_button *map; 70 struct fwnode_handle *child; 71 int i; 72 73 st->num_keys = device_get_child_node_count(dev); 74 if (st->num_keys == 0) { 75 dev_err(dev, "keymap is missing\n"); 76 return -EINVAL; 77 } 78 79 map = devm_kmalloc_array(dev, st->num_keys, sizeof(*map), GFP_KERNEL); 80 if (!map) 81 return -ENOMEM; 82 83 i = 0; 84 device_for_each_child_node(dev, child) { 85 if (fwnode_property_read_u32(child, "press-threshold-microvolt", 86 &map[i].voltage)) { 87 dev_err(dev, "Key with invalid or missing voltage\n"); 88 fwnode_handle_put(child); 89 return -EINVAL; 90 } 91 map[i].voltage /= 1000; 92 93 if (fwnode_property_read_u32(child, "linux,code", 94 &map[i].keycode)) { 95 dev_err(dev, "Key with invalid or missing linux,code\n"); 96 fwnode_handle_put(child); 97 return -EINVAL; 98 } 99 100 i++; 101 } 102 103 st->map = map; 104 return 0; 105 } 106 107 static int adc_keys_probe(struct platform_device *pdev) 108 { 109 struct device *dev = &pdev->dev; 110 struct adc_keys_state *st; 111 struct input_polled_dev *poll_dev; 112 struct input_dev *input; 113 enum iio_chan_type type; 114 int i, value; 115 int error; 116 117 st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL); 118 if (!st) 119 return -ENOMEM; 120 121 st->channel = devm_iio_channel_get(dev, "buttons"); 122 if (IS_ERR(st->channel)) 123 return PTR_ERR(st->channel); 124 125 if (!st->channel->indio_dev) 126 return -ENXIO; 127 128 error = iio_get_channel_type(st->channel, &type); 129 if (error < 0) 130 return error; 131 132 if (type != IIO_VOLTAGE) { 133 dev_err(dev, "Incompatible channel type %d\n", type); 134 return -EINVAL; 135 } 136 137 if (device_property_read_u32(dev, "keyup-threshold-microvolt", 138 &st->keyup_voltage)) { 139 dev_err(dev, "Invalid or missing keyup voltage\n"); 140 return -EINVAL; 141 } 142 st->keyup_voltage /= 1000; 143 144 error = adc_keys_load_keymap(dev, st); 145 if (error) 146 return error; 147 148 poll_dev = devm_input_allocate_polled_device(dev); 149 if (!poll_dev) { 150 dev_err(dev, "failed to allocate input device\n"); 151 return -ENOMEM; 152 } 153 154 if (!device_property_read_u32(dev, "poll-interval", &value)) 155 poll_dev->poll_interval = value; 156 157 poll_dev->poll = adc_keys_poll; 158 poll_dev->private = st; 159 160 input = poll_dev->input; 161 162 input->name = pdev->name; 163 input->phys = "adc-keys/input0"; 164 165 input->id.bustype = BUS_HOST; 166 input->id.vendor = 0x0001; 167 input->id.product = 0x0001; 168 input->id.version = 0x0100; 169 170 __set_bit(EV_KEY, input->evbit); 171 for (i = 0; i < st->num_keys; i++) 172 __set_bit(st->map[i].keycode, input->keybit); 173 174 if (device_property_read_bool(dev, "autorepeat")) 175 __set_bit(EV_REP, input->evbit); 176 177 error = input_register_polled_device(poll_dev); 178 if (error) { 179 dev_err(dev, "Unable to register input device: %d\n", error); 180 return error; 181 } 182 183 return 0; 184 } 185 186 #ifdef CONFIG_OF 187 static const struct of_device_id adc_keys_of_match[] = { 188 { .compatible = "adc-keys", }, 189 { } 190 }; 191 MODULE_DEVICE_TABLE(of, adc_keys_of_match); 192 #endif 193 194 static struct platform_driver __refdata adc_keys_driver = { 195 .driver = { 196 .name = "adc_keys", 197 .of_match_table = of_match_ptr(adc_keys_of_match), 198 }, 199 .probe = adc_keys_probe, 200 }; 201 module_platform_driver(adc_keys_driver); 202 203 MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@free-electrons.com>"); 204 MODULE_DESCRIPTION("Input driver for resistor ladder connected on ADC"); 205 MODULE_LICENSE("GPL v2"); 206