2 * Allwinner sun4i low res adc attached tablet keys driver
4 * Copyright (C) 2014 Hans de Goede <hdegoede@redhat.com>
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.
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.
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.
22 * There are 2 channels, currently this driver only supports channel 0 since
23 * there are no boards known to use channel 1.
26 #include <linux/err.h>
27 #include <linux/init.h>
28 #include <linux/input.h>
29 #include <linux/interrupt.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>
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
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_KEY_EN(x) ((x) << 7)
50 #define HOLD_EN(x) ((x) << 6)
51 #define LEVELB_VOL(x) ((x) << 4) /* 2 bits */
52 #define SAMPLE_RATE(x) ((x) << 2) /* 2 bits */
53 #define ENABLE(x) ((x) << 0)
55 /* LRADC_INTC and LRADC_INTS bits */
56 #define CHAN1_KEYUP_IRQ BIT(12)
57 #define CHAN1_ALRDY_HOLD_IRQ BIT(11)
58 #define CHAN1_HOLD_IRQ BIT(10)
59 #define CHAN1_KEYDOWN_IRQ BIT(9)
60 #define CHAN1_DATA_IRQ BIT(8)
61 #define CHAN0_KEYUP_IRQ BIT(4)
62 #define CHAN0_ALRDY_HOLD_IRQ BIT(3)
63 #define CHAN0_HOLD_IRQ BIT(2)
64 #define CHAN0_KEYDOWN_IRQ BIT(1)
65 #define CHAN0_DATA_IRQ BIT(0)
67 /* struct lradc_variant - Describe sun4i-a10-lradc-keys hardware variant
68 * @divisor_numerator: The numerator of lradc Vref internally divisor
69 * @divisor_denominator: The denominator of lradc Vref internally divisor
71 struct lradc_variant {
73 u8 divisor_denominator;
76 static const struct lradc_variant lradc_variant_a10 = {
77 .divisor_numerator = 2,
78 .divisor_denominator = 3
81 static const struct lradc_variant r_lradc_variant_a83t = {
82 .divisor_numerator = 3,
83 .divisor_denominator = 4
86 struct sun4i_lradc_keymap {
91 struct sun4i_lradc_data {
93 struct input_dev *input;
95 struct regulator *vref_supply;
96 struct sun4i_lradc_keymap *chan0_map;
97 const struct lradc_variant *variant;
103 static irqreturn_t sun4i_lradc_irq(int irq, void *dev_id)
105 struct sun4i_lradc_data *lradc = dev_id;
106 u32 i, ints, val, voltage, diff, keycode = 0, closest = 0xffffffff;
108 ints = readl(lradc->base + LRADC_INTS);
111 * lradc supports only one keypress at a time, release does not give
112 * any info as to which key was released, so we cache the keycode.
115 if (ints & CHAN0_KEYUP_IRQ) {
116 input_report_key(lradc->input, lradc->chan0_keycode, 0);
117 lradc->chan0_keycode = 0;
120 if ((ints & CHAN0_KEYDOWN_IRQ) && lradc->chan0_keycode == 0) {
121 val = readl(lradc->base + LRADC_DATA0) & 0x3f;
122 voltage = val * lradc->vref / 63;
124 for (i = 0; i < lradc->chan0_map_count; i++) {
125 diff = abs(lradc->chan0_map[i].voltage - voltage);
126 if (diff < closest) {
128 keycode = lradc->chan0_map[i].keycode;
132 lradc->chan0_keycode = keycode;
133 input_report_key(lradc->input, lradc->chan0_keycode, 1);
136 input_sync(lradc->input);
138 writel(ints, lradc->base + LRADC_INTS);
143 static int sun4i_lradc_open(struct input_dev *dev)
145 struct sun4i_lradc_data *lradc = input_get_drvdata(dev);
148 error = regulator_enable(lradc->vref_supply);
152 lradc->vref = regulator_get_voltage(lradc->vref_supply) *
153 lradc->variant->divisor_numerator /
154 lradc->variant->divisor_denominator;
156 * Set sample time to 4 ms / 250 Hz. Wait 2 * 4 ms for key to
157 * stabilize on press, wait (1 + 1) * 4 ms for key release
159 writel(FIRST_CONVERT_DLY(2) | LEVELA_B_CNT(1) | HOLD_EN(1) |
160 SAMPLE_RATE(0) | ENABLE(1), lradc->base + LRADC_CTRL);
162 writel(CHAN0_KEYUP_IRQ | CHAN0_KEYDOWN_IRQ, lradc->base + LRADC_INTC);
167 static void sun4i_lradc_close(struct input_dev *dev)
169 struct sun4i_lradc_data *lradc = input_get_drvdata(dev);
171 /* Disable lradc, leave other settings unchanged */
172 writel(FIRST_CONVERT_DLY(2) | LEVELA_B_CNT(1) | HOLD_EN(1) |
173 SAMPLE_RATE(2), lradc->base + LRADC_CTRL);
174 writel(0, lradc->base + LRADC_INTC);
176 regulator_disable(lradc->vref_supply);
179 static int sun4i_lradc_load_dt_keymap(struct device *dev,
180 struct sun4i_lradc_data *lradc)
182 struct device_node *np, *pp;
190 lradc->chan0_map_count = of_get_child_count(np);
191 if (lradc->chan0_map_count == 0) {
192 dev_err(dev, "keymap is missing in device tree\n");
196 lradc->chan0_map = devm_kmalloc_array(dev, lradc->chan0_map_count,
197 sizeof(struct sun4i_lradc_keymap),
199 if (!lradc->chan0_map)
203 for_each_child_of_node(np, pp) {
204 struct sun4i_lradc_keymap *map = &lradc->chan0_map[i];
207 error = of_property_read_u32(pp, "channel", &channel);
208 if (error || channel != 0) {
209 dev_err(dev, "%pOFn: Inval channel prop\n", pp);
213 error = of_property_read_u32(pp, "voltage", &map->voltage);
215 dev_err(dev, "%pOFn: Inval voltage prop\n", pp);
219 error = of_property_read_u32(pp, "linux,code", &map->keycode);
221 dev_err(dev, "%pOFn: Inval linux,code prop\n", pp);
231 static int sun4i_lradc_probe(struct platform_device *pdev)
233 struct sun4i_lradc_data *lradc;
234 struct device *dev = &pdev->dev;
238 lradc = devm_kzalloc(dev, sizeof(struct sun4i_lradc_data), GFP_KERNEL);
242 error = sun4i_lradc_load_dt_keymap(dev, lradc);
246 lradc->variant = of_device_get_match_data(&pdev->dev);
247 if (!lradc->variant) {
248 dev_err(&pdev->dev, "Missing sun4i-a10-lradc-keys variant\n");
252 lradc->vref_supply = devm_regulator_get(dev, "vref");
253 if (IS_ERR(lradc->vref_supply))
254 return PTR_ERR(lradc->vref_supply);
257 lradc->input = devm_input_allocate_device(dev);
261 lradc->input->name = pdev->name;
262 lradc->input->phys = "sun4i_lradc/input0";
263 lradc->input->open = sun4i_lradc_open;
264 lradc->input->close = sun4i_lradc_close;
265 lradc->input->id.bustype = BUS_HOST;
266 lradc->input->id.vendor = 0x0001;
267 lradc->input->id.product = 0x0001;
268 lradc->input->id.version = 0x0100;
270 __set_bit(EV_KEY, lradc->input->evbit);
271 for (i = 0; i < lradc->chan0_map_count; i++)
272 __set_bit(lradc->chan0_map[i].keycode, lradc->input->keybit);
274 input_set_drvdata(lradc->input, lradc);
276 lradc->base = devm_ioremap_resource(dev,
277 platform_get_resource(pdev, IORESOURCE_MEM, 0));
278 if (IS_ERR(lradc->base))
279 return PTR_ERR(lradc->base);
281 error = devm_request_irq(dev, platform_get_irq(pdev, 0),
283 "sun4i-a10-lradc-keys", lradc);
287 error = input_register_device(lradc->input);
294 static const struct of_device_id sun4i_lradc_of_match[] = {
295 { .compatible = "allwinner,sun4i-a10-lradc-keys",
296 .data = &lradc_variant_a10 },
297 { .compatible = "allwinner,sun8i-a83t-r-lradc",
298 .data = &r_lradc_variant_a83t },
301 MODULE_DEVICE_TABLE(of, sun4i_lradc_of_match);
303 static struct platform_driver sun4i_lradc_driver = {
305 .name = "sun4i-a10-lradc-keys",
306 .of_match_table = of_match_ptr(sun4i_lradc_of_match),
308 .probe = sun4i_lradc_probe,
311 module_platform_driver(sun4i_lradc_driver);
313 MODULE_DESCRIPTION("Allwinner sun4i low res adc attached tablet keys driver");
314 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
315 MODULE_LICENSE("GPL");