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/err.h>
18 #include <linux/init.h>
19 #include <linux/input.h>
20 #include <linux/interrupt.h>
21 #include <linux/io.h>
22 #include <linux/module.h>
23 #include <linux/of_platform.h>
24 #include <linux/platform_device.h>
25 #include <linux/regulator/consumer.h>
26 #include <linux/slab.h>
27 
28 #define LRADC_CTRL		0x00
29 #define LRADC_INTC		0x04
30 #define LRADC_INTS		0x08
31 #define LRADC_DATA0		0x0c
32 #define LRADC_DATA1		0x10
33 
34 /* LRADC_CTRL bits */
35 #define FIRST_CONVERT_DLY(x)	((x) << 24) /* 8 bits */
36 #define CHAN_SELECT(x)		((x) << 22) /* 2 bits */
37 #define CONTINUE_TIME_SEL(x)	((x) << 16) /* 4 bits */
38 #define KEY_MODE_SEL(x)		((x) << 12) /* 2 bits */
39 #define LEVELA_B_CNT(x)		((x) << 8)  /* 4 bits */
40 #define HOLD_KEY_EN(x)		((x) << 7)
41 #define HOLD_EN(x)		((x) << 6)
42 #define LEVELB_VOL(x)		((x) << 4)  /* 2 bits */
43 #define SAMPLE_RATE(x)		((x) << 2)  /* 2 bits */
44 #define ENABLE(x)		((x) << 0)
45 
46 /* LRADC_INTC and LRADC_INTS bits */
47 #define CHAN1_KEYUP_IRQ		BIT(12)
48 #define CHAN1_ALRDY_HOLD_IRQ	BIT(11)
49 #define CHAN1_HOLD_IRQ		BIT(10)
50 #define	CHAN1_KEYDOWN_IRQ	BIT(9)
51 #define CHAN1_DATA_IRQ		BIT(8)
52 #define CHAN0_KEYUP_IRQ		BIT(4)
53 #define CHAN0_ALRDY_HOLD_IRQ	BIT(3)
54 #define CHAN0_HOLD_IRQ		BIT(2)
55 #define	CHAN0_KEYDOWN_IRQ	BIT(1)
56 #define CHAN0_DATA_IRQ		BIT(0)
57 
58 /* struct lradc_variant - Describe sun4i-a10-lradc-keys hardware variant
59  * @divisor_numerator:		The numerator of lradc Vref internally divisor
60  * @divisor_denominator:	The denominator of lradc Vref internally divisor
61  */
62 struct lradc_variant {
63 	u8 divisor_numerator;
64 	u8 divisor_denominator;
65 };
66 
67 static const struct lradc_variant lradc_variant_a10 = {
68 	.divisor_numerator = 2,
69 	.divisor_denominator = 3
70 };
71 
72 static const struct lradc_variant r_lradc_variant_a83t = {
73 	.divisor_numerator = 3,
74 	.divisor_denominator = 4
75 };
76 
77 struct sun4i_lradc_keymap {
78 	u32 voltage;
79 	u32 keycode;
80 };
81 
82 struct sun4i_lradc_data {
83 	struct device *dev;
84 	struct input_dev *input;
85 	void __iomem *base;
86 	struct regulator *vref_supply;
87 	struct sun4i_lradc_keymap *chan0_map;
88 	const struct lradc_variant *variant;
89 	u32 chan0_map_count;
90 	u32 chan0_keycode;
91 	u32 vref;
92 };
93 
94 static irqreturn_t sun4i_lradc_irq(int irq, void *dev_id)
95 {
96 	struct sun4i_lradc_data *lradc = dev_id;
97 	u32 i, ints, val, voltage, diff, keycode = 0, closest = 0xffffffff;
98 
99 	ints  = readl(lradc->base + LRADC_INTS);
100 
101 	/*
102 	 * lradc supports only one keypress at a time, release does not give
103 	 * any info as to which key was released, so we cache the keycode.
104 	 */
105 
106 	if (ints & CHAN0_KEYUP_IRQ) {
107 		input_report_key(lradc->input, lradc->chan0_keycode, 0);
108 		lradc->chan0_keycode = 0;
109 	}
110 
111 	if ((ints & CHAN0_KEYDOWN_IRQ) && lradc->chan0_keycode == 0) {
112 		val = readl(lradc->base + LRADC_DATA0) & 0x3f;
113 		voltage = val * lradc->vref / 63;
114 
115 		for (i = 0; i < lradc->chan0_map_count; i++) {
116 			diff = abs(lradc->chan0_map[i].voltage - voltage);
117 			if (diff < closest) {
118 				closest = diff;
119 				keycode = lradc->chan0_map[i].keycode;
120 			}
121 		}
122 
123 		lradc->chan0_keycode = keycode;
124 		input_report_key(lradc->input, lradc->chan0_keycode, 1);
125 	}
126 
127 	input_sync(lradc->input);
128 
129 	writel(ints, lradc->base + LRADC_INTS);
130 
131 	return IRQ_HANDLED;
132 }
133 
134 static int sun4i_lradc_open(struct input_dev *dev)
135 {
136 	struct sun4i_lradc_data *lradc = input_get_drvdata(dev);
137 	int error;
138 
139 	error = regulator_enable(lradc->vref_supply);
140 	if (error)
141 		return error;
142 
143 	lradc->vref = regulator_get_voltage(lradc->vref_supply) *
144 		      lradc->variant->divisor_numerator /
145 		      lradc->variant->divisor_denominator;
146 	/*
147 	 * Set sample time to 4 ms / 250 Hz. Wait 2 * 4 ms for key to
148 	 * stabilize on press, wait (1 + 1) * 4 ms for key release
149 	 */
150 	writel(FIRST_CONVERT_DLY(2) | LEVELA_B_CNT(1) | HOLD_EN(1) |
151 		SAMPLE_RATE(0) | ENABLE(1), lradc->base + LRADC_CTRL);
152 
153 	writel(CHAN0_KEYUP_IRQ | CHAN0_KEYDOWN_IRQ, lradc->base + LRADC_INTC);
154 
155 	return 0;
156 }
157 
158 static void sun4i_lradc_close(struct input_dev *dev)
159 {
160 	struct sun4i_lradc_data *lradc = input_get_drvdata(dev);
161 
162 	/* Disable lradc, leave other settings unchanged */
163 	writel(FIRST_CONVERT_DLY(2) | LEVELA_B_CNT(1) | HOLD_EN(1) |
164 		SAMPLE_RATE(2), lradc->base + LRADC_CTRL);
165 	writel(0, lradc->base + LRADC_INTC);
166 
167 	regulator_disable(lradc->vref_supply);
168 }
169 
170 static int sun4i_lradc_load_dt_keymap(struct device *dev,
171 				      struct sun4i_lradc_data *lradc)
172 {
173 	struct device_node *np, *pp;
174 	int i;
175 	int error;
176 
177 	np = dev->of_node;
178 	if (!np)
179 		return -EINVAL;
180 
181 	lradc->chan0_map_count = of_get_child_count(np);
182 	if (lradc->chan0_map_count == 0) {
183 		dev_err(dev, "keymap is missing in device tree\n");
184 		return -EINVAL;
185 	}
186 
187 	lradc->chan0_map = devm_kmalloc_array(dev, lradc->chan0_map_count,
188 					      sizeof(struct sun4i_lradc_keymap),
189 					      GFP_KERNEL);
190 	if (!lradc->chan0_map)
191 		return -ENOMEM;
192 
193 	i = 0;
194 	for_each_child_of_node(np, pp) {
195 		struct sun4i_lradc_keymap *map = &lradc->chan0_map[i];
196 		u32 channel;
197 
198 		error = of_property_read_u32(pp, "channel", &channel);
199 		if (error || channel != 0) {
200 			dev_err(dev, "%pOFn: Inval channel prop\n", pp);
201 			of_node_put(pp);
202 			return -EINVAL;
203 		}
204 
205 		error = of_property_read_u32(pp, "voltage", &map->voltage);
206 		if (error) {
207 			dev_err(dev, "%pOFn: Inval voltage prop\n", pp);
208 			of_node_put(pp);
209 			return -EINVAL;
210 		}
211 
212 		error = of_property_read_u32(pp, "linux,code", &map->keycode);
213 		if (error) {
214 			dev_err(dev, "%pOFn: Inval linux,code prop\n", pp);
215 			of_node_put(pp);
216 			return -EINVAL;
217 		}
218 
219 		i++;
220 	}
221 
222 	return 0;
223 }
224 
225 static int sun4i_lradc_probe(struct platform_device *pdev)
226 {
227 	struct sun4i_lradc_data *lradc;
228 	struct device *dev = &pdev->dev;
229 	int i;
230 	int error;
231 
232 	lradc = devm_kzalloc(dev, sizeof(struct sun4i_lradc_data), GFP_KERNEL);
233 	if (!lradc)
234 		return -ENOMEM;
235 
236 	error = sun4i_lradc_load_dt_keymap(dev, lradc);
237 	if (error)
238 		return error;
239 
240 	lradc->variant = of_device_get_match_data(&pdev->dev);
241 	if (!lradc->variant) {
242 		dev_err(&pdev->dev, "Missing sun4i-a10-lradc-keys variant\n");
243 		return -EINVAL;
244 	}
245 
246 	lradc->vref_supply = devm_regulator_get(dev, "vref");
247 	if (IS_ERR(lradc->vref_supply))
248 		return PTR_ERR(lradc->vref_supply);
249 
250 	lradc->dev = dev;
251 	lradc->input = devm_input_allocate_device(dev);
252 	if (!lradc->input)
253 		return -ENOMEM;
254 
255 	lradc->input->name = pdev->name;
256 	lradc->input->phys = "sun4i_lradc/input0";
257 	lradc->input->open = sun4i_lradc_open;
258 	lradc->input->close = sun4i_lradc_close;
259 	lradc->input->id.bustype = BUS_HOST;
260 	lradc->input->id.vendor = 0x0001;
261 	lradc->input->id.product = 0x0001;
262 	lradc->input->id.version = 0x0100;
263 
264 	__set_bit(EV_KEY, lradc->input->evbit);
265 	for (i = 0; i < lradc->chan0_map_count; i++)
266 		__set_bit(lradc->chan0_map[i].keycode, lradc->input->keybit);
267 
268 	input_set_drvdata(lradc->input, lradc);
269 
270 	lradc->base = devm_ioremap_resource(dev,
271 			      platform_get_resource(pdev, IORESOURCE_MEM, 0));
272 	if (IS_ERR(lradc->base))
273 		return PTR_ERR(lradc->base);
274 
275 	error = devm_request_irq(dev, platform_get_irq(pdev, 0),
276 				 sun4i_lradc_irq, 0,
277 				 "sun4i-a10-lradc-keys", lradc);
278 	if (error)
279 		return error;
280 
281 	error = input_register_device(lradc->input);
282 	if (error)
283 		return error;
284 
285 	return 0;
286 }
287 
288 static const struct of_device_id sun4i_lradc_of_match[] = {
289 	{ .compatible = "allwinner,sun4i-a10-lradc-keys",
290 		.data = &lradc_variant_a10 },
291 	{ .compatible = "allwinner,sun8i-a83t-r-lradc",
292 		.data = &r_lradc_variant_a83t },
293 	{ /* sentinel */ }
294 };
295 MODULE_DEVICE_TABLE(of, sun4i_lradc_of_match);
296 
297 static struct platform_driver sun4i_lradc_driver = {
298 	.driver = {
299 		.name	= "sun4i-a10-lradc-keys",
300 		.of_match_table = of_match_ptr(sun4i_lradc_of_match),
301 	},
302 	.probe	= sun4i_lradc_probe,
303 };
304 
305 module_platform_driver(sun4i_lradc_driver);
306 
307 MODULE_DESCRIPTION("Allwinner sun4i low res adc attached tablet keys driver");
308 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
309 MODULE_LICENSE("GPL");
310