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 */
 62struct lradc_variant {
 63	u8 divisor_numerator;
 64	u8 divisor_denominator;
 65};
 66
 67static const struct lradc_variant lradc_variant_a10 = {
 68	.divisor_numerator = 2,
 69	.divisor_denominator = 3
 70};
 71
 72static const struct lradc_variant r_lradc_variant_a83t = {
 73	.divisor_numerator = 3,
 74	.divisor_denominator = 4
 75};
 76
 77struct sun4i_lradc_keymap {
 78	u32 voltage;
 79	u32 keycode;
 80};
 81
 82struct 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
 94static 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
134static 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
158static 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
170static 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
225static 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
288static 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};
295MODULE_DEVICE_TABLE(of, sun4i_lradc_of_match);
296
297static 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
305module_platform_driver(sun4i_lradc_driver);
306
307MODULE_DESCRIPTION("Allwinner sun4i low res adc attached tablet keys driver");
308MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
309MODULE_LICENSE("GPL");