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d2912cb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
68077264 AB |
2 | /* |
3 | * Input driver for resistor ladder connected on ADC | |
4 | * | |
5 | * Copyright (c) 2016 Alexandre Belloni | |
68077264 AB |
6 | */ |
7 | ||
8 | #include <linux/err.h> | |
9 | #include <linux/iio/consumer.h> | |
10 | #include <linux/iio/types.h> | |
11 | #include <linux/input.h> | |
68077264 AB |
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 | ||
d0fe37b9 | 32 | static void adc_keys_poll(struct input_dev *input) |
68077264 | 33 | { |
d0fe37b9 | 34 | struct adc_keys_state *st = input_get_drvdata(input); |
68077264 AB |
35 | int i, value, ret; |
36 | u32 diff, closest = 0xffffffff; | |
37 | int keycode = 0; | |
38 | ||
39 | ret = iio_read_channel_processed(st->channel, &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) | |
d0fe37b9 | 57 | input_report_key(input, st->last_key, 0); |
68077264 AB |
58 | |
59 | if (keycode) | |
d0fe37b9 | 60 | input_report_key(input, keycode, 1); |
68077264 | 61 | |
d0fe37b9 | 62 | input_sync(input); |
68077264 AB |
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, st->num_keys, 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(child, "press-threshold-microvolt", | |
85 | &map[i].voltage)) { | |
86 | dev_err(dev, "Key with invalid or missing voltage\n"); | |
87 | fwnode_handle_put(child); | |
88 | return -EINVAL; | |
89 | } | |
90 | map[i].voltage /= 1000; | |
91 | ||
92 | if (fwnode_property_read_u32(child, "linux,code", | |
93 | &map[i].keycode)) { | |
94 | dev_err(dev, "Key with invalid or missing linux,code\n"); | |
95 | fwnode_handle_put(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; | |
68077264 AB |
110 | struct input_dev *input; |
111 | enum iio_chan_type type; | |
112 | int i, value; | |
113 | int error; | |
114 | ||
115 | st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL); | |
116 | if (!st) | |
117 | return -ENOMEM; | |
118 | ||
119 | st->channel = devm_iio_channel_get(dev, "buttons"); | |
120 | if (IS_ERR(st->channel)) | |
121 | return PTR_ERR(st->channel); | |
122 | ||
123 | if (!st->channel->indio_dev) | |
124 | return -ENXIO; | |
125 | ||
126 | error = iio_get_channel_type(st->channel, &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, "keyup-threshold-microvolt", | |
136 | &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 | ||
d0fe37b9 DT |
146 | input = devm_input_allocate_device(dev); |
147 | if (!input) { | |
68077264 AB |
148 | dev_err(dev, "failed to allocate input device\n"); |
149 | return -ENOMEM; | |
150 | } | |
151 | ||
d0fe37b9 | 152 | input_set_drvdata(input, st); |
68077264 AB |
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, "autorepeat")) | |
167 | __set_bit(EV_REP, input->evbit); | |
168 | ||
d0fe37b9 DT |
169 | |
170 | error = input_setup_polling(input, 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, "poll-interval", &value)) | |
177 | input_set_poll_interval(input, value); | |
178 | ||
179 | error = input_register_device(input); | |
68077264 AB |
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 | ||
3e204d6b | 196 | static struct platform_driver adc_keys_driver = { |
68077264 AB |
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"); |