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 */
68struct lradc_variant {
69	u8 divisor_numerator;
70	u8 divisor_denominator;
71	bool has_clock_reset;
72};
73
74static const struct lradc_variant lradc_variant_a10 = {
75	.divisor_numerator = 2,
76	.divisor_denominator = 3
77};
78
79static const struct lradc_variant r_lradc_variant_a83t = {
80	.divisor_numerator = 3,
81	.divisor_denominator = 4
82};
83
84static const struct lradc_variant lradc_variant_r329 = {
85	.divisor_numerator = 3,
86	.divisor_denominator = 4,
87	.has_clock_reset = true,
88};
89
90struct sun4i_lradc_keymap {
91	u32 voltage;
92	u32 keycode;
93};
94
95struct 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
109static 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
149static 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
180err_assert_reset:
181	reset_control_assert(lradc->reset);
182err_disable_reg:
183	regulator_disable(lradc->vref_supply);
184
185	return error;
186}
187
188static 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
202static 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
257static 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
341static 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};
350MODULE_DEVICE_TABLE(of, sun4i_lradc_of_match);
351
352static 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
360module_platform_driver(sun4i_lradc_driver);
361
362MODULE_DESCRIPTION("Allwinner sun4i low res adc attached tablet keys driver");
363MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
364MODULE_LICENSE("GPL");
365