xref: /linux/drivers/input/keyboard/sun4i-lradc-keys.c (revision a3f9e4bc1ec9d8f1e352eb7c1cbaea3168246be7) 
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/pm_wakeup.h>
28 #include <linux/property.h>
29 #include <linux/regulator/consumer.h>
30 #include <linux/reset.h>
31 #include <linux/slab.h>
32 
33 #define LRADC_CTRL		0x00
34 #define LRADC_INTC		0x04
35 #define LRADC_INTS		0x08
36 #define LRADC_DATA0		0x0c
37 #define LRADC_DATA1		0x10
38 
39 /* LRADC_CTRL bits */
40 #define FIRST_CONVERT_DLY(x)	((x) << 24) /* 8 bits */
41 #define CHAN_SELECT(x)		((x) << 22) /* 2 bits */
42 #define CONTINUE_TIME_SEL(x)	((x) << 16) /* 4 bits */
43 #define KEY_MODE_SEL(x)		((x) << 12) /* 2 bits */
44 #define LEVELA_B_CNT(x)		((x) << 8)  /* 4 bits */
45 #define HOLD_KEY_EN(x)		((x) << 7)
46 #define HOLD_EN(x)		((x) << 6)
47 #define LEVELB_VOL(x)		((x) << 4)  /* 2 bits */
48 #define SAMPLE_RATE(x)		((x) << 2)  /* 2 bits */
49 #define ENABLE(x)		((x) << 0)
50 
51 /* LRADC_INTC and LRADC_INTS bits */
52 #define CHAN1_KEYUP_IRQ		BIT(12)
53 #define CHAN1_ALRDY_HOLD_IRQ	BIT(11)
54 #define CHAN1_HOLD_IRQ		BIT(10)
55 #define	CHAN1_KEYDOWN_IRQ	BIT(9)
56 #define CHAN1_DATA_IRQ		BIT(8)
57 #define CHAN0_KEYUP_IRQ		BIT(4)
58 #define CHAN0_ALRDY_HOLD_IRQ	BIT(3)
59 #define CHAN0_HOLD_IRQ		BIT(2)
60 #define	CHAN0_KEYDOWN_IRQ	BIT(1)
61 #define CHAN0_DATA_IRQ		BIT(0)
62 
63 /* struct lradc_variant - Describe sun4i-a10-lradc-keys hardware variant
64  * @divisor_numerator:		The numerator of lradc Vref internally divisor
65  * @divisor_denominator:	The denominator of lradc Vref internally divisor
66  * @has_clock_reset:		If the binding requires a clock and reset
67  */
68 struct lradc_variant {
69 	u8 divisor_numerator;
70 	u8 divisor_denominator;
71 	bool has_clock_reset;
72 };
73 
74 static const struct lradc_variant lradc_variant_a10 = {
75 	.divisor_numerator = 2,
76 	.divisor_denominator = 3
77 };
78 
79 static const struct lradc_variant r_lradc_variant_a83t = {
80 	.divisor_numerator = 3,
81 	.divisor_denominator = 4
82 };
83 
84 static const struct lradc_variant lradc_variant_r329 = {
85 	.divisor_numerator = 3,
86 	.divisor_denominator = 4,
87 	.has_clock_reset = true,
88 };
89 
90 struct sun4i_lradc_keymap {
91 	u32 voltage;
92 	u32 keycode;
93 };
94 
95 struct sun4i_lradc_data {
96 	struct device *dev;
97 	struct input_dev *input;
98 	void __iomem *base;
99 	struct clk *clk;
100 	struct reset_control *reset;
101 	struct regulator *vref_supply;
102 	struct sun4i_lradc_keymap *chan0_map;
103 	const struct lradc_variant *variant;
104 	u32 chan0_map_count;
105 	u32 chan0_keycode;
106 	u32 vref;
107 };
108 
109 static irqreturn_t sun4i_lradc_irq(int irq, void *dev_id)
110 {
111 	struct sun4i_lradc_data *lradc = dev_id;
112 	u32 i, ints, val, voltage, diff, keycode = 0, closest = 0xffffffff;
113 
114 	ints  = readl(lradc->base + LRADC_INTS);
115 
116 	/*
117 	 * lradc supports only one keypress at a time, release does not give
118 	 * any info as to which key was released, so we cache the keycode.
119 	 */
120 
121 	if (ints & CHAN0_KEYUP_IRQ) {
122 		input_report_key(lradc->input, lradc->chan0_keycode, 0);
123 		lradc->chan0_keycode = 0;
124 	}
125 
126 	if ((ints & CHAN0_KEYDOWN_IRQ) && lradc->chan0_keycode == 0) {
127 		val = readl(lradc->base + LRADC_DATA0) & 0x3f;
128 		voltage = val * lradc->vref / 63;
129 
130 		for (i = 0; i < lradc->chan0_map_count; i++) {
131 			diff = abs(lradc->chan0_map[i].voltage - voltage);
132 			if (diff < closest) {
133 				closest = diff;
134 				keycode = lradc->chan0_map[i].keycode;
135 			}
136 		}
137 
138 		lradc->chan0_keycode = keycode;
139 		input_report_key(lradc->input, lradc->chan0_keycode, 1);
140 	}
141 
142 	input_sync(lradc->input);
143 
144 	writel(ints, lradc->base + LRADC_INTS);
145 
146 	return IRQ_HANDLED;
147 }
148 
149 static int sun4i_lradc_open(struct input_dev *dev)
150 {
151 	struct sun4i_lradc_data *lradc = input_get_drvdata(dev);
152 	int error;
153 
154 	error = regulator_enable(lradc->vref_supply);
155 	if (error)
156 		return error;
157 
158 	error = reset_control_deassert(lradc->reset);
159 	if (error)
160 		goto err_disable_reg;
161 
162 	error = clk_prepare_enable(lradc->clk);
163 	if (error)
164 		goto err_assert_reset;
165 
166 	lradc->vref = regulator_get_voltage(lradc->vref_supply) *
167 		      lradc->variant->divisor_numerator /
168 		      lradc->variant->divisor_denominator;
169 	/*
170 	 * Set sample time to 4 ms / 250 Hz. Wait 2 * 4 ms for key to
171 	 * stabilize on press, wait (1 + 1) * 4 ms for key release
172 	 */
173 	writel(FIRST_CONVERT_DLY(2) | LEVELA_B_CNT(1) | HOLD_EN(1) |
174 		SAMPLE_RATE(0) | ENABLE(1), lradc->base + LRADC_CTRL);
175 
176 	writel(CHAN0_KEYUP_IRQ | CHAN0_KEYDOWN_IRQ, lradc->base + LRADC_INTC);
177 
178 	return 0;
179 
180 err_assert_reset:
181 	reset_control_assert(lradc->reset);
182 err_disable_reg:
183 	regulator_disable(lradc->vref_supply);
184 
185 	return error;
186 }
187 
188 static void sun4i_lradc_close(struct input_dev *dev)
189 {
190 	struct sun4i_lradc_data *lradc = input_get_drvdata(dev);
191 
192 	/* Disable lradc, leave other settings unchanged */
193 	writel(FIRST_CONVERT_DLY(2) | LEVELA_B_CNT(1) | HOLD_EN(1) |
194 		SAMPLE_RATE(2), lradc->base + LRADC_CTRL);
195 	writel(0, lradc->base + LRADC_INTC);
196 
197 	clk_disable_unprepare(lradc->clk);
198 	reset_control_assert(lradc->reset);
199 	regulator_disable(lradc->vref_supply);
200 }
201 
202 static int sun4i_lradc_load_dt_keymap(struct device *dev,
203 				      struct sun4i_lradc_data *lradc)
204 {
205 	struct device_node *np, *pp;
206 	int i;
207 	int error;
208 
209 	np = dev->of_node;
210 	if (!np)
211 		return -EINVAL;
212 
213 	lradc->chan0_map_count = of_get_child_count(np);
214 	if (lradc->chan0_map_count == 0) {
215 		dev_err(dev, "keymap is missing in device tree\n");
216 		return -EINVAL;
217 	}
218 
219 	lradc->chan0_map = devm_kmalloc_array(dev, lradc->chan0_map_count,
220 					      sizeof(struct sun4i_lradc_keymap),
221 					      GFP_KERNEL);
222 	if (!lradc->chan0_map)
223 		return -ENOMEM;
224 
225 	i = 0;
226 	for_each_child_of_node(np, pp) {
227 		struct sun4i_lradc_keymap *map = &lradc->chan0_map[i];
228 		u32 channel;
229 
230 		error = of_property_read_u32(pp, "channel", &channel);
231 		if (error || channel != 0) {
232 			dev_err(dev, "%pOFn: Inval channel prop\n", pp);
233 			of_node_put(pp);
234 			return -EINVAL;
235 		}
236 
237 		error = of_property_read_u32(pp, "voltage", &map->voltage);
238 		if (error) {
239 			dev_err(dev, "%pOFn: Inval voltage prop\n", pp);
240 			of_node_put(pp);
241 			return -EINVAL;
242 		}
243 
244 		error = of_property_read_u32(pp, "linux,code", &map->keycode);
245 		if (error) {
246 			dev_err(dev, "%pOFn: Inval linux,code prop\n", pp);
247 			of_node_put(pp);
248 			return -EINVAL;
249 		}
250 
251 		i++;
252 	}
253 
254 	return 0;
255 }
256 
257 static int sun4i_lradc_probe(struct platform_device *pdev)
258 {
259 	struct sun4i_lradc_data *lradc;
260 	struct device *dev = &pdev->dev;
261 	int error, i, irq;
262 
263 	lradc = devm_kzalloc(dev, sizeof(struct sun4i_lradc_data), GFP_KERNEL);
264 	if (!lradc)
265 		return -ENOMEM;
266 
267 	error = sun4i_lradc_load_dt_keymap(dev, lradc);
268 	if (error)
269 		return error;
270 
271 	lradc->variant = of_device_get_match_data(&pdev->dev);
272 	if (!lradc->variant) {
273 		dev_err(&pdev->dev, "Missing sun4i-a10-lradc-keys variant\n");
274 		return -EINVAL;
275 	}
276 
277 	if (lradc->variant->has_clock_reset) {
278 		lradc->clk = devm_clk_get(dev, NULL);
279 		if (IS_ERR(lradc->clk))
280 			return PTR_ERR(lradc->clk);
281 
282 		lradc->reset = devm_reset_control_get_exclusive(dev, NULL);
283 		if (IS_ERR(lradc->reset))
284 			return PTR_ERR(lradc->reset);
285 	}
286 
287 	lradc->vref_supply = devm_regulator_get(dev, "vref");
288 	if (IS_ERR(lradc->vref_supply))
289 		return PTR_ERR(lradc->vref_supply);
290 
291 	lradc->dev = dev;
292 	lradc->input = devm_input_allocate_device(dev);
293 	if (!lradc->input)
294 		return -ENOMEM;
295 
296 	lradc->input->name = pdev->name;
297 	lradc->input->phys = "sun4i_lradc/input0";
298 	lradc->input->open = sun4i_lradc_open;
299 	lradc->input->close = sun4i_lradc_close;
300 	lradc->input->id.bustype = BUS_HOST;
301 	lradc->input->id.vendor = 0x0001;
302 	lradc->input->id.product = 0x0001;
303 	lradc->input->id.version = 0x0100;
304 
305 	__set_bit(EV_KEY, lradc->input->evbit);
306 	for (i = 0; i < lradc->chan0_map_count; i++)
307 		__set_bit(lradc->chan0_map[i].keycode, lradc->input->keybit);
308 
309 	input_set_drvdata(lradc->input, lradc);
310 
311 	lradc->base = devm_platform_ioremap_resource(pdev, 0);
312 	if (IS_ERR(lradc->base))
313 		return PTR_ERR(lradc->base);
314 
315 	irq = platform_get_irq(pdev, 0);
316 	if (irq < 0)
317 		return irq;
318 
319 	error = devm_request_irq(dev, irq, sun4i_lradc_irq, 0,
320 				 "sun4i-a10-lradc-keys", lradc);
321 	if (error)
322 		return error;
323 
324 	error = input_register_device(lradc->input);
325 	if (error)
326 		return error;
327 
328 	if (device_property_read_bool(dev, "wakeup-source")) {
329 		error = dev_pm_set_wake_irq(dev, irq);
330 		if (error)
331 			dev_warn(dev,
332 				 "Failed to set IRQ %d as a wake IRQ: %d\n",
333 				 irq, error);
334 		else
335 			device_set_wakeup_capable(dev, true);
336 	}
337 
338 	return 0;
339 }
340 
341 static const struct of_device_id sun4i_lradc_of_match[] = {
342 	{ .compatible = "allwinner,sun4i-a10-lradc-keys",
343 		.data = &lradc_variant_a10 },
344 	{ .compatible = "allwinner,sun8i-a83t-r-lradc",
345 		.data = &r_lradc_variant_a83t },
346 	{ .compatible = "allwinner,sun50i-r329-lradc",
347 		.data = &lradc_variant_r329 },
348 	{ /* sentinel */ }
349 };
350 MODULE_DEVICE_TABLE(of, sun4i_lradc_of_match);
351 
352 static struct platform_driver sun4i_lradc_driver = {
353 	.driver = {
354 		.name	= "sun4i-a10-lradc-keys",
355 		.of_match_table = of_match_ptr(sun4i_lradc_of_match),
356 	},
357 	.probe	= sun4i_lradc_probe,
358 };
359 
360 module_platform_driver(sun4i_lradc_driver);
361 
362 MODULE_DESCRIPTION("Allwinner sun4i low res adc attached tablet keys driver");
363 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
364 MODULE_LICENSE("GPL");
365