xref: /linux/drivers/input/keyboard/sun4i-lradc-keys.c (revision 7f71507851fc7764b36a3221839607d3a45c2025) 
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 
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 
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 
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 
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 
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