1 /*
2 * Allwinner sun4i low res adc attached tablet keys driver
3 *
4 * Copyright (C) 2014 Hans de Goede <hdegoede@redhat.com>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 */
16
17 /*
18 * Allwinnner sunxi SoCs have a lradc which is specifically designed to have
19 * various (tablet) keys (ie home, back, search, etc). attached to it using
20 * a resistor network. This driver is for the keys on such boards.
21 *
22 * There are 2 channels, currently this driver only supports channel 0 since
23 * there are no boards known to use channel 1.
24 */
25
26 #include <linux/err.h>
27 #include <linux/init.h>
28 #include <linux/input.h>
29 #include <linux/interrupt.h>
30 #include <linux/io.h>
31 #include <linux/module.h>
32 #include <linux/of_platform.h>
33 #include <linux/platform_device.h>
34 #include <linux/regulator/consumer.h>
35 #include <linux/slab.h>
36
37 #define LRADC_CTRL 0x00
38 #define LRADC_INTC 0x04
39 #define LRADC_INTS 0x08
40 #define LRADC_DATA0 0x0c
41 #define LRADC_DATA1 0x10
42
43 /* LRADC_CTRL bits */
44 #define FIRST_CONVERT_DLY(x) ((x) << 24) /* 8 bits */
45 #define CHAN_SELECT(x) ((x) << 22) /* 2 bits */
46 #define CONTINUE_TIME_SEL(x) ((x) << 16) /* 4 bits */
47 #define KEY_MODE_SEL(x) ((x) << 12) /* 2 bits */
48 #define LEVELA_B_CNT(x) ((x) << 8) /* 4 bits */
49 #define HOLD_EN(x) ((x) << 6)
50 #define LEVELB_VOL(x) ((x) << 4) /* 2 bits */
51 #define SAMPLE_RATE(x) ((x) << 2) /* 2 bits */
52 #define ENABLE(x) ((x) << 0)
53
54 /* LRADC_INTC and LRADC_INTS bits */
55 #define CHAN1_KEYUP_IRQ BIT(12)
56 #define CHAN1_ALRDY_HOLD_IRQ BIT(11)
57 #define CHAN1_HOLD_IRQ BIT(10)
58 #define CHAN1_KEYDOWN_IRQ BIT(9)
59 #define CHAN1_DATA_IRQ BIT(8)
60 #define CHAN0_KEYUP_IRQ BIT(4)
61 #define CHAN0_ALRDY_HOLD_IRQ BIT(3)
62 #define CHAN0_HOLD_IRQ BIT(2)
63 #define CHAN0_KEYDOWN_IRQ BIT(1)
64 #define CHAN0_DATA_IRQ BIT(0)
65
66 struct sun4i_lradc_keymap {
67 u32 voltage;
68 u32 keycode;
69 };
70
71 struct sun4i_lradc_data {
72 struct device *dev;
73 struct input_dev *input;
74 void __iomem *base;
75 struct regulator *vref_supply;
76 struct sun4i_lradc_keymap *chan0_map;
77 u32 chan0_map_count;
78 u32 chan0_keycode;
79 u32 vref;
80 };
81
sun4i_lradc_irq(int irq,void * dev_id)82 static irqreturn_t sun4i_lradc_irq(int irq, void *dev_id)
83 {
84 struct sun4i_lradc_data *lradc = dev_id;
85 u32 i, ints, val, voltage, diff, keycode = 0, closest = 0xffffffff;
86
87 ints = readl(lradc->base + LRADC_INTS);
88
89 /*
90 * lradc supports only one keypress at a time, release does not give
91 * any info as to which key was released, so we cache the keycode.
92 */
93
94 if (ints & CHAN0_KEYUP_IRQ) {
95 input_report_key(lradc->input, lradc->chan0_keycode, 0);
96 lradc->chan0_keycode = 0;
97 }
98
99 if ((ints & CHAN0_KEYDOWN_IRQ) && lradc->chan0_keycode == 0) {
100 val = readl(lradc->base + LRADC_DATA0) & 0x3f;
101 voltage = val * lradc->vref / 63;
102
103 for (i = 0; i < lradc->chan0_map_count; i++) {
104 diff = abs(lradc->chan0_map[i].voltage - voltage);
105 if (diff < closest) {
106 closest = diff;
107 keycode = lradc->chan0_map[i].keycode;
108 }
109 }
110
111 lradc->chan0_keycode = keycode;
112 input_report_key(lradc->input, lradc->chan0_keycode, 1);
113 }
114
115 input_sync(lradc->input);
116
117 writel(ints, lradc->base + LRADC_INTS);
118
119 return IRQ_HANDLED;
120 }
121
sun4i_lradc_open(struct input_dev * dev)122 static int sun4i_lradc_open(struct input_dev *dev)
123 {
124 struct sun4i_lradc_data *lradc = input_get_drvdata(dev);
125 int error;
126
127 error = regulator_enable(lradc->vref_supply);
128 if (error)
129 return error;
130
131 /* lradc Vref internally is divided by 2/3 */
132 lradc->vref = regulator_get_voltage(lradc->vref_supply) * 2 / 3;
133
134 /*
135 * Set sample time to 4 ms / 250 Hz. Wait 2 * 4 ms for key to
136 * stabilize on press, wait (1 + 1) * 4 ms for key release
137 */
138 writel(FIRST_CONVERT_DLY(2) | LEVELA_B_CNT(1) | HOLD_EN(1) |
139 SAMPLE_RATE(0) | ENABLE(1), lradc->base + LRADC_CTRL);
140
141 writel(CHAN0_KEYUP_IRQ | CHAN0_KEYDOWN_IRQ, lradc->base + LRADC_INTC);
142
143 return 0;
144 }
145
sun4i_lradc_close(struct input_dev * dev)146 static void sun4i_lradc_close(struct input_dev *dev)
147 {
148 struct sun4i_lradc_data *lradc = input_get_drvdata(dev);
149
150 /* Disable lradc, leave other settings unchanged */
151 writel(FIRST_CONVERT_DLY(2) | LEVELA_B_CNT(1) | HOLD_EN(1) |
152 SAMPLE_RATE(2), lradc->base + LRADC_CTRL);
153 writel(0, lradc->base + LRADC_INTC);
154
155 regulator_disable(lradc->vref_supply);
156 }
157
sun4i_lradc_load_dt_keymap(struct device * dev,struct sun4i_lradc_data * lradc)158 static int sun4i_lradc_load_dt_keymap(struct device *dev,
159 struct sun4i_lradc_data *lradc)
160 {
161 struct device_node *np, *pp;
162 int i;
163 int error;
164
165 np = dev->of_node;
166 if (!np)
167 return -EINVAL;
168
169 lradc->chan0_map_count = of_get_child_count(np);
170 if (lradc->chan0_map_count == 0) {
171 dev_err(dev, "keymap is missing in device tree\n");
172 return -EINVAL;
173 }
174
175 lradc->chan0_map = devm_kmalloc_array(dev, lradc->chan0_map_count,
176 sizeof(struct sun4i_lradc_keymap),
177 GFP_KERNEL);
178 if (!lradc->chan0_map)
179 return -ENOMEM;
180
181 i = 0;
182 for_each_child_of_node(np, pp) {
183 struct sun4i_lradc_keymap *map = &lradc->chan0_map[i];
184 u32 channel;
185
186 error = of_property_read_u32(pp, "channel", &channel);
187 if (error || channel != 0) {
188 dev_err(dev, "%s: Inval channel prop\n", pp->name);
189 return -EINVAL;
190 }
191
192 error = of_property_read_u32(pp, "voltage", &map->voltage);
193 if (error) {
194 dev_err(dev, "%s: Inval voltage prop\n", pp->name);
195 return -EINVAL;
196 }
197
198 error = of_property_read_u32(pp, "linux,code", &map->keycode);
199 if (error) {
200 dev_err(dev, "%s: Inval linux,code prop\n", pp->name);
201 return -EINVAL;
202 }
203
204 i++;
205 }
206
207 return 0;
208 }
209
sun4i_lradc_probe(struct platform_device * pdev)210 static int sun4i_lradc_probe(struct platform_device *pdev)
211 {
212 struct sun4i_lradc_data *lradc;
213 struct device *dev = &pdev->dev;
214 int i;
215 int error;
216
217 lradc = devm_kzalloc(dev, sizeof(struct sun4i_lradc_data), GFP_KERNEL);
218 if (!lradc)
219 return -ENOMEM;
220
221 error = sun4i_lradc_load_dt_keymap(dev, lradc);
222 if (error)
223 return error;
224
225 lradc->vref_supply = devm_regulator_get(dev, "vref");
226 if (IS_ERR(lradc->vref_supply))
227 return PTR_ERR(lradc->vref_supply);
228
229 lradc->dev = dev;
230 lradc->input = devm_input_allocate_device(dev);
231 if (!lradc->input)
232 return -ENOMEM;
233
234 lradc->input->name = pdev->name;
235 lradc->input->phys = "sun4i_lradc/input0";
236 lradc->input->open = sun4i_lradc_open;
237 lradc->input->close = sun4i_lradc_close;
238 lradc->input->id.bustype = BUS_HOST;
239 lradc->input->id.vendor = 0x0001;
240 lradc->input->id.product = 0x0001;
241 lradc->input->id.version = 0x0100;
242
243 __set_bit(EV_KEY, lradc->input->evbit);
244 for (i = 0; i < lradc->chan0_map_count; i++)
245 __set_bit(lradc->chan0_map[i].keycode, lradc->input->keybit);
246
247 input_set_drvdata(lradc->input, lradc);
248
249 lradc->base = devm_ioremap_resource(dev,
250 platform_get_resource(pdev, IORESOURCE_MEM, 0));
251 if (IS_ERR(lradc->base))
252 return PTR_ERR(lradc->base);
253
254 error = devm_request_irq(dev, platform_get_irq(pdev, 0),
255 sun4i_lradc_irq, 0,
256 "sun4i-a10-lradc-keys", lradc);
257 if (error)
258 return error;
259
260 error = input_register_device(lradc->input);
261 if (error)
262 return error;
263
264 return 0;
265 }
266
267 static const struct of_device_id sun4i_lradc_of_match[] = {
268 { .compatible = "allwinner,sun4i-a10-lradc-keys", },
269 { /* sentinel */ }
270 };
271 MODULE_DEVICE_TABLE(of, sun4i_lradc_of_match);
272
273 static struct platform_driver sun4i_lradc_driver = {
274 .driver = {
275 .name = "sun4i-a10-lradc-keys",
276 .of_match_table = of_match_ptr(sun4i_lradc_of_match),
277 },
278 .probe = sun4i_lradc_probe,
279 };
280
281 module_platform_driver(sun4i_lradc_driver);
282
283 MODULE_DESCRIPTION("Allwinner sun4i low res adc attached tablet keys driver");
284 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
285 MODULE_LICENSE("GPL");
286
