1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Allwinner sun4i low res adc attached tablet keys driver
4 *
5 * Copyright (C) 2014 Hans de Goede <hdegoede@redhat.com>
6 */
7
8 /*
9 * Allwinnner sunxi SoCs have a lradc which is specifically designed to have
10 * various (tablet) keys (ie home, back, search, etc). attached to it using
11 * a resistor network. This driver is for the keys on such boards.
12 *
13 * There are 2 channels, currently this driver only supports channel 0 since
14 * there are no boards known to use channel 1.
15 */
16
17 #include <linux/clk.h>
18 #include <linux/err.h>
19 #include <linux/init.h>
20 #include <linux/input.h>
21 #include <linux/interrupt.h>
22 #include <linux/io.h>
23 #include <linux/module.h>
24 #include <linux/of.h>
25 #include <linux/platform_device.h>
26 #include <linux/pm_wakeirq.h>
27 #include <linux/property.h>
28 #include <linux/regulator/consumer.h>
29 #include <linux/reset.h>
30 #include <linux/slab.h>
31
32 #define LRADC_CTRL 0x00
33 #define LRADC_INTC 0x04
34 #define LRADC_INTS 0x08
35 #define LRADC_DATA0 0x0c
36 #define LRADC_DATA1 0x10
37
38 /* LRADC_CTRL bits */
39 #define FIRST_CONVERT_DLY(x) ((x) << 24) /* 8 bits */
40 #define CHAN_SELECT(x) ((x) << 22) /* 2 bits */
41 #define CONTINUE_TIME_SEL(x) ((x) << 16) /* 4 bits */
42 #define KEY_MODE_SEL(x) ((x) << 12) /* 2 bits */
43 #define LEVELA_B_CNT(x) ((x) << 8) /* 4 bits */
44 #define HOLD_KEY_EN(x) ((x) << 7)
45 #define HOLD_EN(x) ((x) << 6)
46 #define LEVELB_VOL(x) ((x) << 4) /* 2 bits */
47 #define SAMPLE_RATE(x) ((x) << 2) /* 2 bits */
48 #define ENABLE(x) ((x) << 0)
49
50 /* LRADC_INTC and LRADC_INTS bits */
51 #define CHAN1_KEYUP_IRQ BIT(12)
52 #define CHAN1_ALRDY_HOLD_IRQ BIT(11)
53 #define CHAN1_HOLD_IRQ BIT(10)
54 #define CHAN1_KEYDOWN_IRQ BIT(9)
55 #define CHAN1_DATA_IRQ BIT(8)
56 #define CHAN0_KEYUP_IRQ BIT(4)
57 #define CHAN0_ALRDY_HOLD_IRQ BIT(3)
58 #define CHAN0_HOLD_IRQ BIT(2)
59 #define CHAN0_KEYDOWN_IRQ BIT(1)
60 #define CHAN0_DATA_IRQ BIT(0)
61
62 /* struct lradc_variant - Describe sun4i-a10-lradc-keys hardware variant
63 * @divisor_numerator: The numerator of lradc Vref internally divisor
64 * @divisor_denominator: The denominator of lradc Vref internally divisor
65 * @has_clock_reset: If the binding requires a clock and reset
66 */
67 struct lradc_variant {
68 u8 divisor_numerator;
69 u8 divisor_denominator;
70 bool has_clock_reset;
71 };
72
73 static const struct lradc_variant lradc_variant_a10 = {
74 .divisor_numerator = 2,
75 .divisor_denominator = 3
76 };
77
78 static const struct lradc_variant r_lradc_variant_a83t = {
79 .divisor_numerator = 3,
80 .divisor_denominator = 4
81 };
82
83 static const struct lradc_variant lradc_variant_r329 = {
84 .divisor_numerator = 3,
85 .divisor_denominator = 4,
86 .has_clock_reset = true,
87 };
88
89 struct sun4i_lradc_keymap {
90 u32 voltage;
91 u32 keycode;
92 };
93
94 struct sun4i_lradc_data {
95 struct device *dev;
96 struct input_dev *input;
97 void __iomem *base;
98 struct clk *clk;
99 struct reset_control *reset;
100 struct regulator *vref_supply;
101 struct sun4i_lradc_keymap *chan0_map;
102 const struct lradc_variant *variant;
103 u32 chan0_map_count;
104 u32 chan0_keycode;
105 u32 vref;
106 };
107
sun4i_lradc_irq(int irq,void * dev_id)108 static irqreturn_t sun4i_lradc_irq(int irq, void *dev_id)
109 {
110 struct sun4i_lradc_data *lradc = dev_id;
111 u32 i, ints, val, voltage, diff, keycode = 0, closest = 0xffffffff;
112
113 ints = readl(lradc->base + LRADC_INTS);
114
115 /*
116 * lradc supports only one keypress at a time, release does not give
117 * any info as to which key was released, so we cache the keycode.
118 */
119
120 if (ints & CHAN0_KEYUP_IRQ) {
121 input_report_key(lradc->input, lradc->chan0_keycode, 0);
122 lradc->chan0_keycode = 0;
123 }
124
125 if ((ints & CHAN0_KEYDOWN_IRQ) && lradc->chan0_keycode == 0) {
126 val = readl(lradc->base + LRADC_DATA0) & 0x3f;
127 voltage = val * lradc->vref / 63;
128
129 for (i = 0; i < lradc->chan0_map_count; i++) {
130 diff = abs(lradc->chan0_map[i].voltage - voltage);
131 if (diff < closest) {
132 closest = diff;
133 keycode = lradc->chan0_map[i].keycode;
134 }
135 }
136
137 lradc->chan0_keycode = keycode;
138 input_report_key(lradc->input, lradc->chan0_keycode, 1);
139 }
140
141 input_sync(lradc->input);
142
143 writel(ints, lradc->base + LRADC_INTS);
144
145 return IRQ_HANDLED;
146 }
147
sun4i_lradc_open(struct input_dev * dev)148 static int sun4i_lradc_open(struct input_dev *dev)
149 {
150 struct sun4i_lradc_data *lradc = input_get_drvdata(dev);
151 int error;
152
153 error = regulator_enable(lradc->vref_supply);
154 if (error)
155 return error;
156
157 error = reset_control_deassert(lradc->reset);
158 if (error)
159 goto err_disable_reg;
160
161 error = clk_prepare_enable(lradc->clk);
162 if (error)
163 goto err_assert_reset;
164
165 lradc->vref = regulator_get_voltage(lradc->vref_supply) *
166 lradc->variant->divisor_numerator /
167 lradc->variant->divisor_denominator;
168 /*
169 * Set sample time to 4 ms / 250 Hz. Wait 2 * 4 ms for key to
170 * stabilize on press, wait (1 + 1) * 4 ms for key release
171 */
172 writel(FIRST_CONVERT_DLY(2) | LEVELA_B_CNT(1) | HOLD_EN(1) |
173 SAMPLE_RATE(0) | ENABLE(1), lradc->base + LRADC_CTRL);
174
175 writel(CHAN0_KEYUP_IRQ | CHAN0_KEYDOWN_IRQ, lradc->base + LRADC_INTC);
176
177 return 0;
178
179 err_assert_reset:
180 reset_control_assert(lradc->reset);
181 err_disable_reg:
182 regulator_disable(lradc->vref_supply);
183
184 return error;
185 }
186
sun4i_lradc_close(struct input_dev * dev)187 static void sun4i_lradc_close(struct input_dev *dev)
188 {
189 struct sun4i_lradc_data *lradc = input_get_drvdata(dev);
190
191 /* Disable lradc, leave other settings unchanged */
192 writel(FIRST_CONVERT_DLY(2) | LEVELA_B_CNT(1) | HOLD_EN(1) |
193 SAMPLE_RATE(2), lradc->base + LRADC_CTRL);
194 writel(0, lradc->base + LRADC_INTC);
195
196 clk_disable_unprepare(lradc->clk);
197 reset_control_assert(lradc->reset);
198 regulator_disable(lradc->vref_supply);
199 }
200
sun4i_lradc_load_dt_keymap(struct device * dev,struct sun4i_lradc_data * lradc)201 static int sun4i_lradc_load_dt_keymap(struct device *dev,
202 struct sun4i_lradc_data *lradc)
203 {
204 struct device_node *np;
205 int i;
206 int error;
207
208 np = dev->of_node;
209 if (!np)
210 return -EINVAL;
211
212 lradc->chan0_map_count = of_get_child_count(np);
213 if (lradc->chan0_map_count == 0) {
214 dev_err(dev, "keymap is missing in device tree\n");
215 return -EINVAL;
216 }
217
218 lradc->chan0_map = devm_kmalloc_array(dev, lradc->chan0_map_count,
219 sizeof(struct sun4i_lradc_keymap),
220 GFP_KERNEL);
221 if (!lradc->chan0_map)
222 return -ENOMEM;
223
224 i = 0;
225 for_each_child_of_node_scoped(np, pp) {
226 struct sun4i_lradc_keymap *map = &lradc->chan0_map[i];
227 u32 channel;
228
229 error = of_property_read_u32(pp, "channel", &channel);
230 if (error || channel != 0) {
231 dev_err(dev, "%pOFn: Inval channel prop\n", pp);
232 return -EINVAL;
233 }
234
235 error = of_property_read_u32(pp, "voltage", &map->voltage);
236 if (error) {
237 dev_err(dev, "%pOFn: Inval voltage prop\n", pp);
238 return -EINVAL;
239 }
240
241 error = of_property_read_u32(pp, "linux,code", &map->keycode);
242 if (error) {
243 dev_err(dev, "%pOFn: Inval linux,code prop\n", pp);
244 return -EINVAL;
245 }
246
247 i++;
248 }
249
250 return 0;
251 }
252
sun4i_lradc_probe(struct platform_device * pdev)253 static int sun4i_lradc_probe(struct platform_device *pdev)
254 {
255 struct sun4i_lradc_data *lradc;
256 struct device *dev = &pdev->dev;
257 int error, i, irq;
258
259 lradc = devm_kzalloc(dev, sizeof(struct sun4i_lradc_data), GFP_KERNEL);
260 if (!lradc)
261 return -ENOMEM;
262
263 error = sun4i_lradc_load_dt_keymap(dev, lradc);
264 if (error)
265 return error;
266
267 lradc->variant = of_device_get_match_data(&pdev->dev);
268 if (!lradc->variant) {
269 dev_err(&pdev->dev, "Missing sun4i-a10-lradc-keys variant\n");
270 return -EINVAL;
271 }
272
273 if (lradc->variant->has_clock_reset) {
274 lradc->clk = devm_clk_get(dev, NULL);
275 if (IS_ERR(lradc->clk))
276 return PTR_ERR(lradc->clk);
277
278 lradc->reset = devm_reset_control_get_exclusive(dev, NULL);
279 if (IS_ERR(lradc->reset))
280 return PTR_ERR(lradc->reset);
281 }
282
283 lradc->vref_supply = devm_regulator_get(dev, "vref");
284 if (IS_ERR(lradc->vref_supply))
285 return PTR_ERR(lradc->vref_supply);
286
287 lradc->dev = dev;
288 lradc->input = devm_input_allocate_device(dev);
289 if (!lradc->input)
290 return -ENOMEM;
291
292 lradc->input->name = pdev->name;
293 lradc->input->phys = "sun4i_lradc/input0";
294 lradc->input->open = sun4i_lradc_open;
295 lradc->input->close = sun4i_lradc_close;
296 lradc->input->id.bustype = BUS_HOST;
297 lradc->input->id.vendor = 0x0001;
298 lradc->input->id.product = 0x0001;
299 lradc->input->id.version = 0x0100;
300
301 __set_bit(EV_KEY, lradc->input->evbit);
302 for (i = 0; i < lradc->chan0_map_count; i++)
303 __set_bit(lradc->chan0_map[i].keycode, lradc->input->keybit);
304
305 input_set_drvdata(lradc->input, lradc);
306
307 lradc->base = devm_platform_ioremap_resource(pdev, 0);
308 if (IS_ERR(lradc->base))
309 return PTR_ERR(lradc->base);
310
311 irq = platform_get_irq(pdev, 0);
312 if (irq < 0)
313 return irq;
314
315 error = devm_request_irq(dev, irq, sun4i_lradc_irq, 0,
316 "sun4i-a10-lradc-keys", lradc);
317 if (error)
318 return error;
319
320 error = input_register_device(lradc->input);
321 if (error)
322 return error;
323
324 if (device_property_read_bool(dev, "wakeup-source")) {
325 error = dev_pm_set_wake_irq(dev, irq);
326 if (error)
327 dev_warn(dev,
328 "Failed to set IRQ %d as a wake IRQ: %d\n",
329 irq, error);
330 else
331 device_set_wakeup_capable(dev, true);
332 }
333
334 return 0;
335 }
336
337 static const struct of_device_id sun4i_lradc_of_match[] = {
338 { .compatible = "allwinner,sun4i-a10-lradc-keys",
339 .data = &lradc_variant_a10 },
340 { .compatible = "allwinner,sun8i-a83t-r-lradc",
341 .data = &r_lradc_variant_a83t },
342 { .compatible = "allwinner,sun50i-r329-lradc",
343 .data = &lradc_variant_r329 },
344 { /* sentinel */ }
345 };
346 MODULE_DEVICE_TABLE(of, sun4i_lradc_of_match);
347
348 static struct platform_driver sun4i_lradc_driver = {
349 .driver = {
350 .name = "sun4i-a10-lradc-keys",
351 .of_match_table = of_match_ptr(sun4i_lradc_of_match),
352 },
353 .probe = sun4i_lradc_probe,
354 };
355
356 module_platform_driver(sun4i_lradc_driver);
357
358 MODULE_DESCRIPTION("Allwinner sun4i low res adc attached tablet keys driver");
359 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
360 MODULE_LICENSE("GPL");
361