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/property.h>
 28#include <linux/regulator/consumer.h>
 29#include <linux/reset.h>
 30#include <linux/slab.h>
 31
 32#define LRADC_CTRL		0x00
 33#define LRADC_INTC		0x04
 34#define LRADC_INTS		0x08
 35#define LRADC_DATA0		0x0c
 36#define LRADC_DATA1		0x10
 37
 38/* LRADC_CTRL bits */
 39#define FIRST_CONVERT_DLY(x)	((x) << 24) /* 8 bits */
 40#define CHAN_SELECT(x)		((x) << 22) /* 2 bits */
 41#define CONTINUE_TIME_SEL(x)	((x) << 16) /* 4 bits */
 42#define KEY_MODE_SEL(x)		((x) << 12) /* 2 bits */
 43#define LEVELA_B_CNT(x)		((x) << 8)  /* 4 bits */
 44#define HOLD_KEY_EN(x)		((x) << 7)
 45#define HOLD_EN(x)		((x) << 6)
 46#define LEVELB_VOL(x)		((x) << 4)  /* 2 bits */
 47#define SAMPLE_RATE(x)		((x) << 2)  /* 2 bits */
 48#define ENABLE(x)		((x) << 0)
 49
 50/* LRADC_INTC and LRADC_INTS bits */
 51#define CHAN1_KEYUP_IRQ		BIT(12)
 52#define CHAN1_ALRDY_HOLD_IRQ	BIT(11)
 53#define CHAN1_HOLD_IRQ		BIT(10)
 54#define	CHAN1_KEYDOWN_IRQ	BIT(9)
 55#define CHAN1_DATA_IRQ		BIT(8)
 56#define CHAN0_KEYUP_IRQ		BIT(4)
 57#define CHAN0_ALRDY_HOLD_IRQ	BIT(3)
 58#define CHAN0_HOLD_IRQ		BIT(2)
 59#define	CHAN0_KEYDOWN_IRQ	BIT(1)
 60#define CHAN0_DATA_IRQ		BIT(0)
 61
 62/* struct lradc_variant - Describe sun4i-a10-lradc-keys hardware variant
 63 * @divisor_numerator:		The numerator of lradc Vref internally divisor
 64 * @divisor_denominator:	The denominator of lradc Vref internally divisor
 65 * @has_clock_reset:		If the binding requires a clock and reset
 66 */
 67struct lradc_variant {
 68	u8 divisor_numerator;
 69	u8 divisor_denominator;
 70	bool has_clock_reset;
 71};
 72
 73static const struct lradc_variant lradc_variant_a10 = {
 74	.divisor_numerator = 2,
 75	.divisor_denominator = 3
 76};
 77
 78static const struct lradc_variant r_lradc_variant_a83t = {
 79	.divisor_numerator = 3,
 80	.divisor_denominator = 4
 81};
 82
 83static const struct lradc_variant lradc_variant_r329 = {
 84	.divisor_numerator = 3,
 85	.divisor_denominator = 4,
 86	.has_clock_reset = true,
 87};
 88
 89struct sun4i_lradc_keymap {
 90	u32 voltage;
 91	u32 keycode;
 92};
 93
 94struct sun4i_lradc_data {
 95	struct device *dev;
 96	struct input_dev *input;
 97	void __iomem *base;
 98	struct clk *clk;
 99	struct reset_control *reset;
100	struct regulator *vref_supply;
101	struct sun4i_lradc_keymap *chan0_map;
102	const struct lradc_variant *variant;
103	u32 chan0_map_count;
104	u32 chan0_keycode;
105	u32 vref;
106};
107
108static irqreturn_t sun4i_lradc_irq(int irq, void *dev_id)
109{
110	struct sun4i_lradc_data *lradc = dev_id;
111	u32 i, ints, val, voltage, diff, keycode = 0, closest = 0xffffffff;
112
113	ints  = readl(lradc->base + LRADC_INTS);
114
115	/*
116	 * lradc supports only one keypress at a time, release does not give
117	 * any info as to which key was released, so we cache the keycode.
118	 */
119
120	if (ints & CHAN0_KEYUP_IRQ) {
121		input_report_key(lradc->input, lradc->chan0_keycode, 0);
122		lradc->chan0_keycode = 0;
123	}
124
125	if ((ints & CHAN0_KEYDOWN_IRQ) && lradc->chan0_keycode == 0) {
126		val = readl(lradc->base + LRADC_DATA0) & 0x3f;
127		voltage = val * lradc->vref / 63;
128
129		for (i = 0; i < lradc->chan0_map_count; i++) {
130			diff = abs(lradc->chan0_map[i].voltage - voltage);
131			if (diff < closest) {
132				closest = diff;
133				keycode = lradc->chan0_map[i].keycode;
134			}
135		}
136
137		lradc->chan0_keycode = keycode;
138		input_report_key(lradc->input, lradc->chan0_keycode, 1);
139	}
140
141	input_sync(lradc->input);
142
143	writel(ints, lradc->base + LRADC_INTS);
144
145	return IRQ_HANDLED;
146}
147
148static int sun4i_lradc_open(struct input_dev *dev)
149{
150	struct sun4i_lradc_data *lradc = input_get_drvdata(dev);
151	int error;
152
153	error = regulator_enable(lradc->vref_supply);
154	if (error)
155		return error;
156
157	error = reset_control_deassert(lradc->reset);
158	if (error)
159		goto err_disable_reg;
160
161	error = clk_prepare_enable(lradc->clk);
162	if (error)
163		goto err_assert_reset;
164
165	lradc->vref = regulator_get_voltage(lradc->vref_supply) *
166		      lradc->variant->divisor_numerator /
167		      lradc->variant->divisor_denominator;
168	/*
169	 * Set sample time to 4 ms / 250 Hz. Wait 2 * 4 ms for key to
170	 * stabilize on press, wait (1 + 1) * 4 ms for key release
171	 */
172	writel(FIRST_CONVERT_DLY(2) | LEVELA_B_CNT(1) | HOLD_EN(1) |
173		SAMPLE_RATE(0) | ENABLE(1), lradc->base + LRADC_CTRL);
174
175	writel(CHAN0_KEYUP_IRQ | CHAN0_KEYDOWN_IRQ, lradc->base + LRADC_INTC);
176
177	return 0;
178
179err_assert_reset:
180	reset_control_assert(lradc->reset);
181err_disable_reg:
182	regulator_disable(lradc->vref_supply);
183
184	return error;
185}
186
187static void sun4i_lradc_close(struct input_dev *dev)
188{
189	struct sun4i_lradc_data *lradc = input_get_drvdata(dev);
190
191	/* Disable lradc, leave other settings unchanged */
192	writel(FIRST_CONVERT_DLY(2) | LEVELA_B_CNT(1) | HOLD_EN(1) |
193		SAMPLE_RATE(2), lradc->base + LRADC_CTRL);
194	writel(0, lradc->base + LRADC_INTC);
195
196	clk_disable_unprepare(lradc->clk);
197	reset_control_assert(lradc->reset);
198	regulator_disable(lradc->vref_supply);
199}
200
201static int sun4i_lradc_load_dt_keymap(struct device *dev,
202				      struct sun4i_lradc_data *lradc)
203{
204	struct device_node *np;
205	int i;
206	int error;
207
208	np = dev->of_node;
209	if (!np)
210		return -EINVAL;
211
212	lradc->chan0_map_count = of_get_child_count(np);
213	if (lradc->chan0_map_count == 0) {
214		dev_err(dev, "keymap is missing in device tree\n");
215		return -EINVAL;
216	}
217
218	lradc->chan0_map = devm_kmalloc_array(dev, lradc->chan0_map_count,
219					      sizeof(struct sun4i_lradc_keymap),
220					      GFP_KERNEL);
221	if (!lradc->chan0_map)
222		return -ENOMEM;
223
224	i = 0;
225	for_each_child_of_node_scoped(np, pp) {
226		struct sun4i_lradc_keymap *map = &lradc->chan0_map[i];
227		u32 channel;
228
229		error = of_property_read_u32(pp, "channel", &channel);
230		if (error || channel != 0) {
231			dev_err(dev, "%pOFn: Inval channel prop\n", pp);
232			return -EINVAL;
233		}
234
235		error = of_property_read_u32(pp, "voltage", &map->voltage);
236		if (error) {
237			dev_err(dev, "%pOFn: Inval voltage prop\n", pp);
238			return -EINVAL;
239		}
240
241		error = of_property_read_u32(pp, "linux,code", &map->keycode);
242		if (error) {
243			dev_err(dev, "%pOFn: Inval linux,code prop\n", pp);
244			return -EINVAL;
245		}
246
247		i++;
248	}
249
250	return 0;
251}
252
253static int sun4i_lradc_probe(struct platform_device *pdev)
254{
255	struct sun4i_lradc_data *lradc;
256	struct device *dev = &pdev->dev;
257	int error, i, irq;
258
259	lradc = devm_kzalloc(dev, sizeof(struct sun4i_lradc_data), GFP_KERNEL);
260	if (!lradc)
261		return -ENOMEM;
262
263	error = sun4i_lradc_load_dt_keymap(dev, lradc);
264	if (error)
265		return error;
266
267	lradc->variant = of_device_get_match_data(&pdev->dev);
268	if (!lradc->variant) {
269		dev_err(&pdev->dev, "Missing sun4i-a10-lradc-keys variant\n");
270		return -EINVAL;
271	}
272
273	if (lradc->variant->has_clock_reset) {
274		lradc->clk = devm_clk_get(dev, NULL);
275		if (IS_ERR(lradc->clk))
276			return PTR_ERR(lradc->clk);
277
278		lradc->reset = devm_reset_control_get_exclusive(dev, NULL);
279		if (IS_ERR(lradc->reset))
280			return PTR_ERR(lradc->reset);
281	}
282
283	lradc->vref_supply = devm_regulator_get(dev, "vref");
284	if (IS_ERR(lradc->vref_supply))
285		return PTR_ERR(lradc->vref_supply);
286
287	lradc->dev = dev;
288	lradc->input = devm_input_allocate_device(dev);
289	if (!lradc->input)
290		return -ENOMEM;
291
292	lradc->input->name = pdev->name;
293	lradc->input->phys = "sun4i_lradc/input0";
294	lradc->input->open = sun4i_lradc_open;
295	lradc->input->close = sun4i_lradc_close;
296	lradc->input->id.bustype = BUS_HOST;
297	lradc->input->id.vendor = 0x0001;
298	lradc->input->id.product = 0x0001;
299	lradc->input->id.version = 0x0100;
300
301	__set_bit(EV_KEY, lradc->input->evbit);
302	for (i = 0; i < lradc->chan0_map_count; i++)
303		__set_bit(lradc->chan0_map[i].keycode, lradc->input->keybit);
304
305	input_set_drvdata(lradc->input, lradc);
306
307	lradc->base = devm_platform_ioremap_resource(pdev, 0);
308	if (IS_ERR(lradc->base))
309		return PTR_ERR(lradc->base);
310
311	irq = platform_get_irq(pdev, 0);
312	if (irq < 0)
313		return irq;
314
315	error = devm_request_irq(dev, irq, sun4i_lradc_irq, 0,
316				 "sun4i-a10-lradc-keys", lradc);
317	if (error)
318		return error;
319
320	error = input_register_device(lradc->input);
321	if (error)
322		return error;
323
324	if (device_property_read_bool(dev, "wakeup-source")) {
325		error = dev_pm_set_wake_irq(dev, irq);
326		if (error)
327			dev_warn(dev,
328				 "Failed to set IRQ %d as a wake IRQ: %d\n",
329				 irq, error);
330		else
331			device_set_wakeup_capable(dev, true);
332	}
333
334	return 0;
335}
336
337static const struct of_device_id sun4i_lradc_of_match[] = {
338	{ .compatible = "allwinner,sun4i-a10-lradc-keys",
339		.data = &lradc_variant_a10 },
340	{ .compatible = "allwinner,sun8i-a83t-r-lradc",
341		.data = &r_lradc_variant_a83t },
342	{ .compatible = "allwinner,sun50i-r329-lradc",
343		.data = &lradc_variant_r329 },
344	{ /* sentinel */ }
345};
346MODULE_DEVICE_TABLE(of, sun4i_lradc_of_match);
347
348static struct platform_driver sun4i_lradc_driver = {
349	.driver = {
350		.name	= "sun4i-a10-lradc-keys",
351		.of_match_table = of_match_ptr(sun4i_lradc_of_match),
352	},
353	.probe	= sun4i_lradc_probe,
354};
355
356module_platform_driver(sun4i_lradc_driver);
357
358MODULE_DESCRIPTION("Allwinner sun4i low res adc attached tablet keys driver");
359MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
360MODULE_LICENSE("GPL");