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17#include <linux/kernel.h>
18#include <linux/module.h>
19#include <linux/init.h>
20#include <linux/interrupt.h>
21#include <linux/input.h>
22#include <linux/device.h>
23#include <linux/platform_device.h>
24#include <linux/gpio.h>
25#include <linux/rotary_encoder.h>
26#include <linux/slab.h>
27#include <linux/of_platform.h>
28#include <linux/of_gpio.h>
29
30#define DRV_NAME "rotary-encoder"
31
32struct rotary_encoder {
33 struct input_dev *input;
34 const struct rotary_encoder_platform_data *pdata;
35
36 unsigned int axis;
37 unsigned int pos;
38
39 unsigned int irq_a;
40 unsigned int irq_b;
41
42 bool armed;
43 unsigned char dir;
44
45 char last_stable;
46};
47
48static int rotary_encoder_get_state(const struct rotary_encoder_platform_data *pdata)
49{
50 int a = !!gpio_get_value(pdata->gpio_a);
51 int b = !!gpio_get_value(pdata->gpio_b);
52
53 a ^= pdata->inverted_a;
54 b ^= pdata->inverted_b;
55
56 return ((a << 1) | b);
57}
58
59static void rotary_encoder_report_event(struct rotary_encoder *encoder)
60{
61 const struct rotary_encoder_platform_data *pdata = encoder->pdata;
62
63 if (pdata->relative_axis) {
64 input_report_rel(encoder->input,
65 pdata->axis, encoder->dir ? -1 : 1);
66 } else {
67 unsigned int pos = encoder->pos;
68
69 if (encoder->dir) {
70
71 if (pdata->rollover)
72 pos += pdata->steps;
73 if (pos)
74 pos--;
75 } else {
76
77 if (pdata->rollover || pos < pdata->steps)
78 pos++;
79 }
80
81 if (pdata->rollover)
82 pos %= pdata->steps;
83
84 encoder->pos = pos;
85 input_report_abs(encoder->input, pdata->axis, encoder->pos);
86 }
87
88 input_sync(encoder->input);
89}
90
91static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
92{
93 struct rotary_encoder *encoder = dev_id;
94 int state;
95
96 state = rotary_encoder_get_state(encoder->pdata);
97
98 switch (state) {
99 case 0x0:
100 if (encoder->armed) {
101 rotary_encoder_report_event(encoder);
102 encoder->armed = false;
103 }
104 break;
105
106 case 0x1:
107 case 0x2:
108 if (encoder->armed)
109 encoder->dir = state - 1;
110 break;
111
112 case 0x3:
113 encoder->armed = true;
114 break;
115 }
116
117 return IRQ_HANDLED;
118}
119
120static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
121{
122 struct rotary_encoder *encoder = dev_id;
123 int state;
124
125 state = rotary_encoder_get_state(encoder->pdata);
126
127 switch (state) {
128 case 0x00:
129 case 0x03:
130 if (state != encoder->last_stable) {
131 rotary_encoder_report_event(encoder);
132 encoder->last_stable = state;
133 }
134 break;
135
136 case 0x01:
137 case 0x02:
138 encoder->dir = (encoder->last_stable + state) & 0x01;
139 break;
140 }
141
142 return IRQ_HANDLED;
143}
144
145#ifdef CONFIG_OF
146static struct of_device_id rotary_encoder_of_match[] = {
147 { .compatible = "rotary-encoder", },
148 { },
149};
150MODULE_DEVICE_TABLE(of, rotary_encoder_of_match);
151
152static struct rotary_encoder_platform_data *rotary_encoder_parse_dt(struct device *dev)
153{
154 const struct of_device_id *of_id =
155 of_match_device(rotary_encoder_of_match, dev);
156 struct device_node *np = dev->of_node;
157 struct rotary_encoder_platform_data *pdata;
158 enum of_gpio_flags flags;
159
160 if (!of_id || !np)
161 return NULL;
162
163 pdata = kzalloc(sizeof(struct rotary_encoder_platform_data),
164 GFP_KERNEL);
165 if (!pdata)
166 return ERR_PTR(-ENOMEM);
167
168 of_property_read_u32(np, "rotary-encoder,steps", &pdata->steps);
169 of_property_read_u32(np, "linux,axis", &pdata->axis);
170
171 pdata->gpio_a = of_get_gpio_flags(np, 0, &flags);
172 pdata->inverted_a = flags & OF_GPIO_ACTIVE_LOW;
173
174 pdata->gpio_b = of_get_gpio_flags(np, 1, &flags);
175 pdata->inverted_b = flags & OF_GPIO_ACTIVE_LOW;
176
177 pdata->relative_axis = !!of_get_property(np,
178 "rotary-encoder,relative-axis", NULL);
179 pdata->rollover = !!of_get_property(np,
180 "rotary-encoder,rollover", NULL);
181 pdata->half_period = !!of_get_property(np,
182 "rotary-encoder,half-period", NULL);
183
184 return pdata;
185}
186#else
187static inline struct rotary_encoder_platform_data *
188rotary_encoder_parse_dt(struct device *dev)
189{
190 return NULL;
191}
192#endif
193
194static int rotary_encoder_probe(struct platform_device *pdev)
195{
196 struct device *dev = &pdev->dev;
197 const struct rotary_encoder_platform_data *pdata = dev_get_platdata(dev);
198 struct rotary_encoder *encoder;
199 struct input_dev *input;
200 irq_handler_t handler;
201 int err;
202
203 if (!pdata) {
204 pdata = rotary_encoder_parse_dt(dev);
205 if (IS_ERR(pdata))
206 return PTR_ERR(pdata);
207
208 if (!pdata) {
209 dev_err(dev, "missing platform data\n");
210 return -EINVAL;
211 }
212 }
213
214 encoder = kzalloc(sizeof(struct rotary_encoder), GFP_KERNEL);
215 input = input_allocate_device();
216 if (!encoder || !input) {
217 err = -ENOMEM;
218 goto exit_free_mem;
219 }
220
221 encoder->input = input;
222 encoder->pdata = pdata;
223
224 input->name = pdev->name;
225 input->id.bustype = BUS_HOST;
226 input->dev.parent = dev;
227
228 if (pdata->relative_axis) {
229 input->evbit[0] = BIT_MASK(EV_REL);
230 input->relbit[0] = BIT_MASK(pdata->axis);
231 } else {
232 input->evbit[0] = BIT_MASK(EV_ABS);
233 input_set_abs_params(encoder->input,
234 pdata->axis, 0, pdata->steps, 0, 1);
235 }
236
237
238 err = gpio_request_one(pdata->gpio_a, GPIOF_IN, dev_name(dev));
239 if (err) {
240 dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_a);
241 goto exit_free_mem;
242 }
243
244 err = gpio_request_one(pdata->gpio_b, GPIOF_IN, dev_name(dev));
245 if (err) {
246 dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_b);
247 goto exit_free_gpio_a;
248 }
249
250 encoder->irq_a = gpio_to_irq(pdata->gpio_a);
251 encoder->irq_b = gpio_to_irq(pdata->gpio_b);
252
253
254 if (pdata->half_period) {
255 handler = &rotary_encoder_half_period_irq;
256 encoder->last_stable = rotary_encoder_get_state(pdata);
257 } else {
258 handler = &rotary_encoder_irq;
259 }
260
261 err = request_irq(encoder->irq_a, handler,
262 IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
263 DRV_NAME, encoder);
264 if (err) {
265 dev_err(dev, "unable to request IRQ %d\n", encoder->irq_a);
266 goto exit_free_gpio_b;
267 }
268
269 err = request_irq(encoder->irq_b, handler,
270 IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
271 DRV_NAME, encoder);
272 if (err) {
273 dev_err(dev, "unable to request IRQ %d\n", encoder->irq_b);
274 goto exit_free_irq_a;
275 }
276
277 err = input_register_device(input);
278 if (err) {
279 dev_err(dev, "failed to register input device\n");
280 goto exit_free_irq_b;
281 }
282
283 platform_set_drvdata(pdev, encoder);
284
285 return 0;
286
287exit_free_irq_b:
288 free_irq(encoder->irq_b, encoder);
289exit_free_irq_a:
290 free_irq(encoder->irq_a, encoder);
291exit_free_gpio_b:
292 gpio_free(pdata->gpio_b);
293exit_free_gpio_a:
294 gpio_free(pdata->gpio_a);
295exit_free_mem:
296 input_free_device(input);
297 kfree(encoder);
298 if (!dev_get_platdata(&pdev->dev))
299 kfree(pdata);
300
301 return err;
302}
303
304static int rotary_encoder_remove(struct platform_device *pdev)
305{
306 struct rotary_encoder *encoder = platform_get_drvdata(pdev);
307 const struct rotary_encoder_platform_data *pdata = encoder->pdata;
308
309 free_irq(encoder->irq_a, encoder);
310 free_irq(encoder->irq_b, encoder);
311 gpio_free(pdata->gpio_a);
312 gpio_free(pdata->gpio_b);
313
314 input_unregister_device(encoder->input);
315 kfree(encoder);
316
317 if (!dev_get_platdata(&pdev->dev))
318 kfree(pdata);
319
320 return 0;
321}
322
323static struct platform_driver rotary_encoder_driver = {
324 .probe = rotary_encoder_probe,
325 .remove = rotary_encoder_remove,
326 .driver = {
327 .name = DRV_NAME,
328 .owner = THIS_MODULE,
329 .of_match_table = of_match_ptr(rotary_encoder_of_match),
330 }
331};
332module_platform_driver(rotary_encoder_driver);
333
334MODULE_ALIAS("platform:" DRV_NAME);
335MODULE_DESCRIPTION("GPIO rotary encoder driver");
336MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>, Johan Hovold");
337MODULE_LICENSE("GPL v2");
338
