summaryrefslogtreecommitdiff
path: root/drivers/input/keyboard/sun4i-lradc-keys.c
blob: 4a796bed48acc10b13cc235d4871ce82e6ed7368 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Allwinner sun4i low res adc attached tablet keys driver
 *
 * Copyright (C) 2014 Hans de Goede <hdegoede@redhat.com>
 */

/*
 * Allwinnner sunxi SoCs have a lradc which is specifically designed to have
 * various (tablet) keys (ie home, back, search, etc). attached to it using
 * a resistor network. This driver is for the keys on such boards.
 *
 * There are 2 channels, currently this driver only supports channel 0 since
 * there are no boards known to use channel 1.
 */

#include <linux/err.h>
#include <linux/init.h>
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/regulator/consumer.h>
#include <linux/slab.h>

#define LRADC_CTRL		0x00
#define LRADC_INTC		0x04
#define LRADC_INTS		0x08
#define LRADC_DATA0		0x0c
#define LRADC_DATA1		0x10

/* LRADC_CTRL bits */
#define FIRST_CONVERT_DLY(x)	((x) << 24) /* 8 bits */
#define CHAN_SELECT(x)		((x) << 22) /* 2 bits */
#define CONTINUE_TIME_SEL(x)	((x) << 16) /* 4 bits */
#define KEY_MODE_SEL(x)		((x) << 12) /* 2 bits */
#define LEVELA_B_CNT(x)		((x) << 8)  /* 4 bits */
#define HOLD_KEY_EN(x)		((x) << 7)
#define HOLD_EN(x)		((x) << 6)
#define LEVELB_VOL(x)		((x) << 4)  /* 2 bits */
#define SAMPLE_RATE(x)		((x) << 2)  /* 2 bits */
#define ENABLE(x)		((x) << 0)

/* LRADC_INTC and LRADC_INTS bits */
#define CHAN1_KEYUP_IRQ		BIT(12)
#define CHAN1_ALRDY_HOLD_IRQ	BIT(11)
#define CHAN1_HOLD_IRQ		BIT(10)
#define	CHAN1_KEYDOWN_IRQ	BIT(9)
#define CHAN1_DATA_IRQ		BIT(8)
#define CHAN0_KEYUP_IRQ		BIT(4)
#define CHAN0_ALRDY_HOLD_IRQ	BIT(3)
#define CHAN0_HOLD_IRQ		BIT(2)
#define	CHAN0_KEYDOWN_IRQ	BIT(1)
#define CHAN0_DATA_IRQ		BIT(0)

/* struct lradc_variant - Describe sun4i-a10-lradc-keys hardware variant
 * @divisor_numerator:		The numerator of lradc Vref internally divisor
 * @divisor_denominator:	The denominator of lradc Vref internally divisor
 */
struct lradc_variant {
	u8 divisor_numerator;
	u8 divisor_denominator;
};

static const struct lradc_variant lradc_variant_a10 = {
	.divisor_numerator = 2,
	.divisor_denominator = 3
};

static const struct lradc_variant r_lradc_variant_a83t = {
	.divisor_numerator = 3,
	.divisor_denominator = 4
};

struct sun4i_lradc_keymap {
	u32 voltage;
	u32 keycode;
};

struct sun4i_lradc_data {
	struct device *dev;
	struct input_dev *input;
	void __iomem *base;
	struct regulator *vref_supply;
	struct sun4i_lradc_keymap *chan0_map;
	const struct lradc_variant *variant;
	u32 chan0_map_count;
	u32 chan0_keycode;
	u32 vref;
};

static irqreturn_t sun4i_lradc_irq(int irq, void *dev_id)
{
	struct sun4i_lradc_data *lradc = dev_id;
	u32 i, ints, val, voltage, diff, keycode = 0, closest = 0xffffffff;

	ints  = readl(lradc->base + LRADC_INTS);

	/*
	 * lradc supports only one keypress at a time, release does not give
	 * any info as to which key was released, so we cache the keycode.
	 */

	if (ints & CHAN0_KEYUP_IRQ) {
		input_report_key(lradc->input, lradc->chan0_keycode, 0);
		lradc->chan0_keycode = 0;
	}

	if ((ints & CHAN0_KEYDOWN_IRQ) && lradc->chan0_keycode == 0) {
		val = readl(lradc->base + LRADC_DATA0) & 0x3f;
		voltage = val * lradc->vref / 63;

		for (i = 0; i < lradc->chan0_map_count; i++) {
			diff = abs(lradc->chan0_map[i].voltage - voltage);
			if (diff < closest) {
				closest = diff;
				keycode = lradc->chan0_map[i].keycode;
			}
		}

		lradc->chan0_keycode = keycode;
		input_report_key(lradc->input, lradc->chan0_keycode, 1);
	}

	input_sync(lradc->input);

	writel(ints, lradc->base + LRADC_INTS);

	return IRQ_HANDLED;
}

static int sun4i_lradc_open(struct input_dev *dev)
{
	struct sun4i_lradc_data *lradc = input_get_drvdata(dev);
	int error;

	error = regulator_enable(lradc->vref_supply);
	if (error)
		return error;

	lradc->vref = regulator_get_voltage(lradc->vref_supply) *
		      lradc->variant->divisor_numerator /
		      lradc->variant->divisor_denominator;
	/*
	 * Set sample time to 4 ms / 250 Hz. Wait 2 * 4 ms for key to
	 * stabilize on press, wait (1 + 1) * 4 ms for key release
	 */
	writel(FIRST_CONVERT_DLY(2) | LEVELA_B_CNT(1) | HOLD_EN(1) |
		SAMPLE_RATE(0) | ENABLE(1), lradc->base + LRADC_CTRL);

	writel(CHAN0_KEYUP_IRQ | CHAN0_KEYDOWN_IRQ, lradc->base + LRADC_INTC);

	return 0;
}

static void sun4i_lradc_close(struct input_dev *dev)
{
	struct sun4i_lradc_data *lradc = input_get_drvdata(dev);

	/* Disable lradc, leave other settings unchanged */
	writel(FIRST_CONVERT_DLY(2) | LEVELA_B_CNT(1) | HOLD_EN(1) |
		SAMPLE_RATE(2), lradc->base + LRADC_CTRL);
	writel(0, lradc->base + LRADC_INTC);

	regulator_disable(lradc->vref_supply);
}

static int sun4i_lradc_load_dt_keymap(struct device *dev,
				      struct sun4i_lradc_data *lradc)
{
	struct device_node *np, *pp;
	int i;
	int error;

	np = dev->of_node;
	if (!np)
		return -EINVAL;

	lradc->chan0_map_count = of_get_child_count(np);
	if (lradc->chan0_map_count == 0) {
		dev_err(dev, "keymap is missing in device tree\n");
		return -EINVAL;
	}

	lradc->chan0_map = devm_kmalloc_array(dev, lradc->chan0_map_count,
					      sizeof(struct sun4i_lradc_keymap),
					      GFP_KERNEL);
	if (!lradc->chan0_map)
		return -ENOMEM;

	i = 0;
	for_each_child_of_node(np, pp) {
		struct sun4i_lradc_keymap *map = &lradc->chan0_map[i];
		u32 channel;

		error = of_property_read_u32(pp, "channel", &channel);
		if (error || channel != 0) {
			dev_err(dev, "%pOFn: Inval channel prop\n", pp);
			of_node_put(pp);
			return -EINVAL;
		}

		error = of_property_read_u32(pp, "voltage", &map->voltage);
		if (error) {
			dev_err(dev, "%pOFn: Inval voltage prop\n", pp);
			of_node_put(pp);
			return -EINVAL;
		}

		error = of_property_read_u32(pp, "linux,code", &map->keycode);
		if (error) {
			dev_err(dev, "%pOFn: Inval linux,code prop\n", pp);
			of_node_put(pp);
			return -EINVAL;
		}

		i++;
	}

	return 0;
}

static int sun4i_lradc_probe(struct platform_device *pdev)
{
	struct sun4i_lradc_data *lradc;
	struct device *dev = &pdev->dev;
	int i;
	int error;

	lradc = devm_kzalloc(dev, sizeof(struct sun4i_lradc_data), GFP_KERNEL);
	if (!lradc)
		return -ENOMEM;

	error = sun4i_lradc_load_dt_keymap(dev, lradc);
	if (error)
		return error;

	lradc->variant = of_device_get_match_data(&pdev->dev);
	if (!lradc->variant) {
		dev_err(&pdev->dev, "Missing sun4i-a10-lradc-keys variant\n");
		return -EINVAL;
	}

	lradc->vref_supply = devm_regulator_get(dev, "vref");
	if (IS_ERR(lradc->vref_supply))
		return PTR_ERR(lradc->vref_supply);

	lradc->dev = dev;
	lradc->input = devm_input_allocate_device(dev);
	if (!lradc->input)
		return -ENOMEM;

	lradc->input->name = pdev->name;
	lradc->input->phys = "sun4i_lradc/input0";
	lradc->input->open = sun4i_lradc_open;
	lradc->input->close = sun4i_lradc_close;
	lradc->input->id.bustype = BUS_HOST;
	lradc->input->id.vendor = 0x0001;
	lradc->input->id.product = 0x0001;
	lradc->input->id.version = 0x0100;

	__set_bit(EV_KEY, lradc->input->evbit);
	for (i = 0; i < lradc->chan0_map_count; i++)
		__set_bit(lradc->chan0_map[i].keycode, lradc->input->keybit);

	input_set_drvdata(lradc->input, lradc);

	lradc->base = devm_ioremap_resource(dev,
			      platform_get_resource(pdev, IORESOURCE_MEM, 0));
	if (IS_ERR(lradc->base))
		return PTR_ERR(lradc->base);

	error = devm_request_irq(dev, platform_get_irq(pdev, 0),
				 sun4i_lradc_irq, 0,
				 "sun4i-a10-lradc-keys", lradc);
	if (error)
		return error;

	error = input_register_device(lradc->input);
	if (error)
		return error;

	return 0;
}

static const struct of_device_id sun4i_lradc_of_match[] = {
	{ .compatible = "allwinner,sun4i-a10-lradc-keys",
		.data = &lradc_variant_a10 },
	{ .compatible = "allwinner,sun8i-a83t-r-lradc",
		.data = &r_lradc_variant_a83t },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, sun4i_lradc_of_match);

static struct platform_driver sun4i_lradc_driver = {
	.driver = {
		.name	= "sun4i-a10-lradc-keys",
		.of_match_table = of_match_ptr(sun4i_lradc_of_match),
	},
	.probe	= sun4i_lradc_probe,
};

module_platform_driver(sun4i_lradc_driver);

MODULE_DESCRIPTION("Allwinner sun4i low res adc attached tablet keys driver");
MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
MODULE_LICENSE("GPL");