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/kernel.h> |
13 | #include <linux/module.h> |
14 | #include <linux/of.h> |
15 | #include <linux/platform_device.h> |
16 | #include <linux/property.h> |
17 | #include <linux/slab.h> |
18 | |
19 | struct adc_keys_button { |
20 | u32 voltage; |
21 | u32 keycode; |
22 | }; |
23 | |
24 | struct adc_keys_state { |
25 | struct iio_channel *channel; |
26 | u32 num_keys; |
27 | u32 last_key; |
28 | u32 keyup_voltage; |
29 | const struct adc_keys_button *map; |
30 | }; |
31 | |
32 | static void adc_keys_poll(struct input_dev *input) |
33 | { |
34 | struct adc_keys_state *st = input_get_drvdata(dev: input); |
35 | int i, value, ret; |
36 | u32 diff, closest = 0xffffffff; |
37 | int keycode = 0; |
38 | |
39 | ret = iio_read_channel_processed(chan: st->channel, val: &value); |
40 | if (unlikely(ret < 0)) { |
41 | /* Forcibly release key if any was pressed */ |
42 | value = st->keyup_voltage; |
43 | } else { |
44 | for (i = 0; i < st->num_keys; i++) { |
45 | diff = abs(st->map[i].voltage - value); |
46 | if (diff < closest) { |
47 | closest = diff; |
48 | keycode = st->map[i].keycode; |
49 | } |
50 | } |
51 | } |
52 | |
53 | if (abs(st->keyup_voltage - value) < closest) |
54 | keycode = 0; |
55 | |
56 | if (st->last_key && st->last_key != keycode) |
57 | input_report_key(dev: input, code: st->last_key, value: 0); |
58 | |
59 | if (keycode) |
60 | input_report_key(dev: input, code: keycode, value: 1); |
61 | |
62 | input_sync(dev: input); |
63 | st->last_key = keycode; |
64 | } |
65 | |
66 | static int adc_keys_load_keymap(struct device *dev, struct adc_keys_state *st) |
67 | { |
68 | struct adc_keys_button *map; |
69 | struct fwnode_handle *child; |
70 | int i; |
71 | |
72 | st->num_keys = device_get_child_node_count(dev); |
73 | if (st->num_keys == 0) { |
74 | dev_err(dev, "keymap is missing\n" ); |
75 | return -EINVAL; |
76 | } |
77 | |
78 | map = devm_kmalloc_array(dev, n: st->num_keys, size: sizeof(*map), GFP_KERNEL); |
79 | if (!map) |
80 | return -ENOMEM; |
81 | |
82 | i = 0; |
83 | device_for_each_child_node(dev, child) { |
84 | if (fwnode_property_read_u32(fwnode: child, propname: "press-threshold-microvolt" , |
85 | val: &map[i].voltage)) { |
86 | dev_err(dev, "Key with invalid or missing voltage\n" ); |
87 | fwnode_handle_put(fwnode: child); |
88 | return -EINVAL; |
89 | } |
90 | map[i].voltage /= 1000; |
91 | |
92 | if (fwnode_property_read_u32(fwnode: child, propname: "linux,code" , |
93 | val: &map[i].keycode)) { |
94 | dev_err(dev, "Key with invalid or missing linux,code\n" ); |
95 | fwnode_handle_put(fwnode: child); |
96 | return -EINVAL; |
97 | } |
98 | |
99 | i++; |
100 | } |
101 | |
102 | st->map = map; |
103 | return 0; |
104 | } |
105 | |
106 | static int adc_keys_probe(struct platform_device *pdev) |
107 | { |
108 | struct device *dev = &pdev->dev; |
109 | struct adc_keys_state *st; |
110 | struct input_dev *input; |
111 | enum iio_chan_type type; |
112 | int i, value; |
113 | int error; |
114 | |
115 | st = devm_kzalloc(dev, size: sizeof(*st), GFP_KERNEL); |
116 | if (!st) |
117 | return -ENOMEM; |
118 | |
119 | st->channel = devm_iio_channel_get(dev, consumer_channel: "buttons" ); |
120 | if (IS_ERR(ptr: st->channel)) |
121 | return PTR_ERR(ptr: st->channel); |
122 | |
123 | if (!st->channel->indio_dev) |
124 | return -ENXIO; |
125 | |
126 | error = iio_get_channel_type(channel: st->channel, type: &type); |
127 | if (error < 0) |
128 | return error; |
129 | |
130 | if (type != IIO_VOLTAGE) { |
131 | dev_err(dev, "Incompatible channel type %d\n" , type); |
132 | return -EINVAL; |
133 | } |
134 | |
135 | if (device_property_read_u32(dev, propname: "keyup-threshold-microvolt" , |
136 | val: &st->keyup_voltage)) { |
137 | dev_err(dev, "Invalid or missing keyup voltage\n" ); |
138 | return -EINVAL; |
139 | } |
140 | st->keyup_voltage /= 1000; |
141 | |
142 | error = adc_keys_load_keymap(dev, st); |
143 | if (error) |
144 | return error; |
145 | |
146 | input = devm_input_allocate_device(dev); |
147 | if (!input) { |
148 | dev_err(dev, "failed to allocate input device\n" ); |
149 | return -ENOMEM; |
150 | } |
151 | |
152 | input_set_drvdata(dev: input, data: st); |
153 | |
154 | input->name = pdev->name; |
155 | input->phys = "adc-keys/input0" ; |
156 | |
157 | input->id.bustype = BUS_HOST; |
158 | input->id.vendor = 0x0001; |
159 | input->id.product = 0x0001; |
160 | input->id.version = 0x0100; |
161 | |
162 | __set_bit(EV_KEY, input->evbit); |
163 | for (i = 0; i < st->num_keys; i++) |
164 | __set_bit(st->map[i].keycode, input->keybit); |
165 | |
166 | if (device_property_read_bool(dev, propname: "autorepeat" )) |
167 | __set_bit(EV_REP, input->evbit); |
168 | |
169 | |
170 | error = input_setup_polling(dev: input, poll_fn: adc_keys_poll); |
171 | if (error) { |
172 | dev_err(dev, "Unable to set up polling: %d\n" , error); |
173 | return error; |
174 | } |
175 | |
176 | if (!device_property_read_u32(dev, propname: "poll-interval" , val: &value)) |
177 | input_set_poll_interval(dev: input, interval: value); |
178 | |
179 | error = input_register_device(input); |
180 | if (error) { |
181 | dev_err(dev, "Unable to register input device: %d\n" , error); |
182 | return error; |
183 | } |
184 | |
185 | return 0; |
186 | } |
187 | |
188 | #ifdef CONFIG_OF |
189 | static const struct of_device_id adc_keys_of_match[] = { |
190 | { .compatible = "adc-keys" , }, |
191 | { } |
192 | }; |
193 | MODULE_DEVICE_TABLE(of, adc_keys_of_match); |
194 | #endif |
195 | |
196 | static struct platform_driver adc_keys_driver = { |
197 | .driver = { |
198 | .name = "adc_keys" , |
199 | .of_match_table = of_match_ptr(adc_keys_of_match), |
200 | }, |
201 | .probe = adc_keys_probe, |
202 | }; |
203 | module_platform_driver(adc_keys_driver); |
204 | |
205 | MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@free-electrons.com>" ); |
206 | MODULE_DESCRIPTION("Input driver for resistor ladder connected on ADC" ); |
207 | MODULE_LICENSE("GPL v2" ); |
208 | |