1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * rotary_encoder.c |
4 | * |
5 | * (c) 2009 Daniel Mack <daniel@caiaq.de> |
6 | * Copyright (C) 2011 Johan Hovold <jhovold@gmail.com> |
7 | * |
8 | * state machine code inspired by code from Tim Ruetz |
9 | * |
10 | * A generic driver for rotary encoders connected to GPIO lines. |
11 | * See file:Documentation/input/devices/rotary-encoder.rst for more information |
12 | */ |
13 | |
14 | #include <linux/kernel.h> |
15 | #include <linux/module.h> |
16 | #include <linux/interrupt.h> |
17 | #include <linux/input.h> |
18 | #include <linux/device.h> |
19 | #include <linux/platform_device.h> |
20 | #include <linux/gpio/consumer.h> |
21 | #include <linux/slab.h> |
22 | #include <linux/of.h> |
23 | #include <linux/pm.h> |
24 | #include <linux/property.h> |
25 | |
26 | #define DRV_NAME "rotary-encoder" |
27 | |
28 | enum rotary_encoder_encoding { |
29 | ROTENC_GRAY, |
30 | ROTENC_BINARY, |
31 | }; |
32 | |
33 | struct rotary_encoder { |
34 | struct input_dev *input; |
35 | |
36 | struct mutex access_mutex; |
37 | |
38 | u32 steps; |
39 | u32 axis; |
40 | bool relative_axis; |
41 | bool rollover; |
42 | enum rotary_encoder_encoding encoding; |
43 | |
44 | unsigned int pos; |
45 | |
46 | struct gpio_descs *gpios; |
47 | |
48 | unsigned int *irq; |
49 | |
50 | bool armed; |
51 | signed char dir; /* 1 - clockwise, -1 - CCW */ |
52 | |
53 | unsigned int last_stable; |
54 | }; |
55 | |
56 | static unsigned int rotary_encoder_get_state(struct rotary_encoder *encoder) |
57 | { |
58 | int i; |
59 | unsigned int ret = 0; |
60 | |
61 | for (i = 0; i < encoder->gpios->ndescs; ++i) { |
62 | int val = gpiod_get_value_cansleep(desc: encoder->gpios->desc[i]); |
63 | |
64 | /* convert from gray encoding to normal */ |
65 | if (encoder->encoding == ROTENC_GRAY && ret & 1) |
66 | val = !val; |
67 | |
68 | ret = ret << 1 | val; |
69 | } |
70 | |
71 | return ret & 3; |
72 | } |
73 | |
74 | static void rotary_encoder_report_event(struct rotary_encoder *encoder) |
75 | { |
76 | if (encoder->relative_axis) { |
77 | input_report_rel(dev: encoder->input, |
78 | code: encoder->axis, value: encoder->dir); |
79 | } else { |
80 | unsigned int pos = encoder->pos; |
81 | |
82 | if (encoder->dir < 0) { |
83 | /* turning counter-clockwise */ |
84 | if (encoder->rollover) |
85 | pos += encoder->steps; |
86 | if (pos) |
87 | pos--; |
88 | } else { |
89 | /* turning clockwise */ |
90 | if (encoder->rollover || pos < encoder->steps) |
91 | pos++; |
92 | } |
93 | |
94 | if (encoder->rollover) |
95 | pos %= encoder->steps; |
96 | |
97 | encoder->pos = pos; |
98 | input_report_abs(dev: encoder->input, code: encoder->axis, value: encoder->pos); |
99 | } |
100 | |
101 | input_sync(dev: encoder->input); |
102 | } |
103 | |
104 | static irqreturn_t rotary_encoder_irq(int irq, void *dev_id) |
105 | { |
106 | struct rotary_encoder *encoder = dev_id; |
107 | unsigned int state; |
108 | |
109 | mutex_lock(&encoder->access_mutex); |
110 | |
111 | state = rotary_encoder_get_state(encoder); |
112 | |
113 | switch (state) { |
114 | case 0x0: |
115 | if (encoder->armed) { |
116 | rotary_encoder_report_event(encoder); |
117 | encoder->armed = false; |
118 | } |
119 | break; |
120 | |
121 | case 0x1: |
122 | case 0x3: |
123 | if (encoder->armed) |
124 | encoder->dir = 2 - state; |
125 | break; |
126 | |
127 | case 0x2: |
128 | encoder->armed = true; |
129 | break; |
130 | } |
131 | |
132 | mutex_unlock(lock: &encoder->access_mutex); |
133 | |
134 | return IRQ_HANDLED; |
135 | } |
136 | |
137 | static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id) |
138 | { |
139 | struct rotary_encoder *encoder = dev_id; |
140 | unsigned int state; |
141 | |
142 | mutex_lock(&encoder->access_mutex); |
143 | |
144 | state = rotary_encoder_get_state(encoder); |
145 | |
146 | if (state & 1) { |
147 | encoder->dir = ((encoder->last_stable - state + 1) % 4) - 1; |
148 | } else { |
149 | if (state != encoder->last_stable) { |
150 | rotary_encoder_report_event(encoder); |
151 | encoder->last_stable = state; |
152 | } |
153 | } |
154 | |
155 | mutex_unlock(lock: &encoder->access_mutex); |
156 | |
157 | return IRQ_HANDLED; |
158 | } |
159 | |
160 | static irqreturn_t rotary_encoder_quarter_period_irq(int irq, void *dev_id) |
161 | { |
162 | struct rotary_encoder *encoder = dev_id; |
163 | unsigned int state; |
164 | |
165 | mutex_lock(&encoder->access_mutex); |
166 | |
167 | state = rotary_encoder_get_state(encoder); |
168 | |
169 | if ((encoder->last_stable + 1) % 4 == state) |
170 | encoder->dir = 1; |
171 | else if (encoder->last_stable == (state + 1) % 4) |
172 | encoder->dir = -1; |
173 | else |
174 | goto out; |
175 | |
176 | rotary_encoder_report_event(encoder); |
177 | |
178 | out: |
179 | encoder->last_stable = state; |
180 | mutex_unlock(lock: &encoder->access_mutex); |
181 | |
182 | return IRQ_HANDLED; |
183 | } |
184 | |
185 | static int rotary_encoder_probe(struct platform_device *pdev) |
186 | { |
187 | struct device *dev = &pdev->dev; |
188 | struct rotary_encoder *encoder; |
189 | struct input_dev *input; |
190 | irq_handler_t handler; |
191 | u32 steps_per_period; |
192 | unsigned int i; |
193 | int err; |
194 | |
195 | encoder = devm_kzalloc(dev, size: sizeof(struct rotary_encoder), GFP_KERNEL); |
196 | if (!encoder) |
197 | return -ENOMEM; |
198 | |
199 | mutex_init(&encoder->access_mutex); |
200 | |
201 | device_property_read_u32(dev, propname: "rotary-encoder,steps" , val: &encoder->steps); |
202 | |
203 | err = device_property_read_u32(dev, propname: "rotary-encoder,steps-per-period" , |
204 | val: &steps_per_period); |
205 | if (err) { |
206 | /* |
207 | * The 'half-period' property has been deprecated, you must |
208 | * use 'steps-per-period' and set an appropriate value, but |
209 | * we still need to parse it to maintain compatibility. If |
210 | * neither property is present we fall back to the one step |
211 | * per period behavior. |
212 | */ |
213 | steps_per_period = device_property_read_bool(dev, |
214 | propname: "rotary-encoder,half-period" ) ? 2 : 1; |
215 | } |
216 | |
217 | encoder->rollover = |
218 | device_property_read_bool(dev, propname: "rotary-encoder,rollover" ); |
219 | |
220 | if (!device_property_present(dev, propname: "rotary-encoder,encoding" ) || |
221 | !device_property_match_string(dev, propname: "rotary-encoder,encoding" , |
222 | string: "gray" )) { |
223 | dev_info(dev, "gray" ); |
224 | encoder->encoding = ROTENC_GRAY; |
225 | } else if (!device_property_match_string(dev, propname: "rotary-encoder,encoding" , |
226 | string: "binary" )) { |
227 | dev_info(dev, "binary" ); |
228 | encoder->encoding = ROTENC_BINARY; |
229 | } else { |
230 | dev_err(dev, "unknown encoding setting\n" ); |
231 | return -EINVAL; |
232 | } |
233 | |
234 | device_property_read_u32(dev, propname: "linux,axis" , val: &encoder->axis); |
235 | encoder->relative_axis = |
236 | device_property_read_bool(dev, propname: "rotary-encoder,relative-axis" ); |
237 | |
238 | encoder->gpios = devm_gpiod_get_array(dev, NULL, flags: GPIOD_IN); |
239 | if (IS_ERR(ptr: encoder->gpios)) |
240 | return dev_err_probe(dev, err: PTR_ERR(ptr: encoder->gpios), fmt: "unable to get gpios\n" ); |
241 | if (encoder->gpios->ndescs < 2) { |
242 | dev_err(dev, "not enough gpios found\n" ); |
243 | return -EINVAL; |
244 | } |
245 | |
246 | input = devm_input_allocate_device(dev); |
247 | if (!input) |
248 | return -ENOMEM; |
249 | |
250 | encoder->input = input; |
251 | |
252 | input->name = pdev->name; |
253 | input->id.bustype = BUS_HOST; |
254 | |
255 | if (encoder->relative_axis) |
256 | input_set_capability(dev: input, EV_REL, code: encoder->axis); |
257 | else |
258 | input_set_abs_params(dev: input, |
259 | axis: encoder->axis, min: 0, max: encoder->steps, fuzz: 0, flat: 1); |
260 | |
261 | switch (steps_per_period >> (encoder->gpios->ndescs - 2)) { |
262 | case 4: |
263 | handler = &rotary_encoder_quarter_period_irq; |
264 | encoder->last_stable = rotary_encoder_get_state(encoder); |
265 | break; |
266 | case 2: |
267 | handler = &rotary_encoder_half_period_irq; |
268 | encoder->last_stable = rotary_encoder_get_state(encoder); |
269 | break; |
270 | case 1: |
271 | handler = &rotary_encoder_irq; |
272 | break; |
273 | default: |
274 | dev_err(dev, "'%d' is not a valid steps-per-period value\n" , |
275 | steps_per_period); |
276 | return -EINVAL; |
277 | } |
278 | |
279 | encoder->irq = |
280 | devm_kcalloc(dev, |
281 | n: encoder->gpios->ndescs, size: sizeof(*encoder->irq), |
282 | GFP_KERNEL); |
283 | if (!encoder->irq) |
284 | return -ENOMEM; |
285 | |
286 | for (i = 0; i < encoder->gpios->ndescs; ++i) { |
287 | encoder->irq[i] = gpiod_to_irq(desc: encoder->gpios->desc[i]); |
288 | |
289 | err = devm_request_threaded_irq(dev, irq: encoder->irq[i], |
290 | NULL, thread_fn: handler, |
291 | IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING | |
292 | IRQF_ONESHOT, |
293 | DRV_NAME, dev_id: encoder); |
294 | if (err) { |
295 | dev_err(dev, "unable to request IRQ %d (gpio#%d)\n" , |
296 | encoder->irq[i], i); |
297 | return err; |
298 | } |
299 | } |
300 | |
301 | err = input_register_device(input); |
302 | if (err) { |
303 | dev_err(dev, "failed to register input device\n" ); |
304 | return err; |
305 | } |
306 | |
307 | device_init_wakeup(dev, |
308 | enable: device_property_read_bool(dev, propname: "wakeup-source" )); |
309 | |
310 | platform_set_drvdata(pdev, data: encoder); |
311 | |
312 | return 0; |
313 | } |
314 | |
315 | static int rotary_encoder_suspend(struct device *dev) |
316 | { |
317 | struct rotary_encoder *encoder = dev_get_drvdata(dev); |
318 | unsigned int i; |
319 | |
320 | if (device_may_wakeup(dev)) { |
321 | for (i = 0; i < encoder->gpios->ndescs; ++i) |
322 | enable_irq_wake(irq: encoder->irq[i]); |
323 | } |
324 | |
325 | return 0; |
326 | } |
327 | |
328 | static int rotary_encoder_resume(struct device *dev) |
329 | { |
330 | struct rotary_encoder *encoder = dev_get_drvdata(dev); |
331 | unsigned int i; |
332 | |
333 | if (device_may_wakeup(dev)) { |
334 | for (i = 0; i < encoder->gpios->ndescs; ++i) |
335 | disable_irq_wake(irq: encoder->irq[i]); |
336 | } |
337 | |
338 | return 0; |
339 | } |
340 | |
341 | static DEFINE_SIMPLE_DEV_PM_OPS(rotary_encoder_pm_ops, |
342 | rotary_encoder_suspend, rotary_encoder_resume); |
343 | |
344 | #ifdef CONFIG_OF |
345 | static const struct of_device_id rotary_encoder_of_match[] = { |
346 | { .compatible = "rotary-encoder" , }, |
347 | { }, |
348 | }; |
349 | MODULE_DEVICE_TABLE(of, rotary_encoder_of_match); |
350 | #endif |
351 | |
352 | static struct platform_driver rotary_encoder_driver = { |
353 | .probe = rotary_encoder_probe, |
354 | .driver = { |
355 | .name = DRV_NAME, |
356 | .pm = pm_sleep_ptr(&rotary_encoder_pm_ops), |
357 | .of_match_table = of_match_ptr(rotary_encoder_of_match), |
358 | } |
359 | }; |
360 | module_platform_driver(rotary_encoder_driver); |
361 | |
362 | MODULE_ALIAS("platform:" DRV_NAME); |
363 | MODULE_DESCRIPTION("GPIO rotary encoder driver" ); |
364 | MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>, Johan Hovold" ); |
365 | MODULE_LICENSE("GPL v2" ); |
366 | |