1// SPDX-License-Identifier: BSD-2-Clause OR GPL-2.0-or-later
2/*
3 * Dell Wyse 3020 a.k.a. "Ariel" Power Button Driver
4 *
5 * Copyright (C) 2020 Lubomir Rintel
6 */
7
8#include <linux/device.h>
9#include <linux/gfp.h>
10#include <linux/input.h>
11#include <linux/interrupt.h>
12#include <linux/mod_devicetable.h>
13#include <linux/module.h>
14#include <linux/spi/spi.h>
15
16#define RESP_COUNTER(response)	(response.header & 0x3)
17#define RESP_SIZE(response)	((response.header >> 2) & 0x3)
18#define RESP_TYPE(response)	((response.header >> 4) & 0xf)
19
20struct ec_input_response {
21	u8 reserved;
22	u8 header;
23	u8 data[3];
24} __packed;
25
26struct ariel_pwrbutton {
27	struct spi_device *client;
28	struct input_dev *input;
29	u8 msg_counter;
30};
31
32static int ec_input_read(struct ariel_pwrbutton *priv,
33			 struct ec_input_response *response)
34{
35	u8 read_request[] = { 0x00, 0x5a, 0xa5, 0x00, 0x00 };
36	struct spi_device *spi = priv->client;
37	struct spi_transfer t = {
38		.tx_buf = read_request,
39		.rx_buf = response,
40		.len = sizeof(read_request),
41	};
42
43	compiletime_assert(sizeof(read_request) == sizeof(*response),
44			   "SPI xfer request/response size mismatch");
45
46	return spi_sync_transfer(spi, &t, 1);
47}
48
49static irqreturn_t ec_input_interrupt(int irq, void *dev_id)
50{
51	struct ariel_pwrbutton *priv = dev_id;
52	struct spi_device *spi = priv->client;
53	struct ec_input_response response;
54	int error;
55	int i;
56
57	error = ec_input_read(priv, &response);
58	if (error < 0) {
59		dev_err(&spi->dev, "EC read failed: %d\n", error);
60		goto out;
61	}
62
63	if (priv->msg_counter == RESP_COUNTER(response)) {
64		dev_warn(&spi->dev, "No new data to read?\n");
65		goto out;
66	}
67
68	priv->msg_counter = RESP_COUNTER(response);
69
70	if (RESP_TYPE(response) != 0x3 && RESP_TYPE(response) != 0xc) {
71		dev_dbg(&spi->dev, "Ignoring message that's not kbd data\n");
72		goto out;
73	}
74
75	for (i = 0; i < RESP_SIZE(response); i++) {
76		switch (response.data[i]) {
77		case 0x74:
78			input_report_key(priv->input, KEY_POWER, 1);
79			input_sync(priv->input);
80			break;
81		case 0xf4:
82			input_report_key(priv->input, KEY_POWER, 0);
83			input_sync(priv->input);
84			break;
85		default:
86			dev_dbg(&spi->dev, "Unknown scan code: %02x\n",
87				response.data[i]);
88		}
89	}
90
91out:
92	return IRQ_HANDLED;
93}
94
95static int ariel_pwrbutton_probe(struct spi_device *spi)
96{
97	struct ec_input_response response;
98	struct ariel_pwrbutton *priv;
99	int error;
100
101	if (!spi->irq) {
102		dev_err(&spi->dev, "Missing IRQ.\n");
103		return -EINVAL;
104	}
105
106	priv = devm_kzalloc(&spi->dev, sizeof(*priv), GFP_KERNEL);
107	if (!priv)
108		return -ENOMEM;
109
110	priv->client = spi;
111	spi_set_drvdata(spi, priv);
112
113	priv->input = devm_input_allocate_device(&spi->dev);
114	if (!priv->input)
115		return -ENOMEM;
116	priv->input->name = "Power Button";
117	priv->input->dev.parent = &spi->dev;
118	input_set_capability(priv->input, EV_KEY, KEY_POWER);
119	error = input_register_device(priv->input);
120	if (error) {
121		dev_err(&spi->dev, "error registering input device: %d\n", error);
122		return error;
123	}
124
125	error = ec_input_read(priv, &response);
126	if (error < 0) {
127		dev_err(&spi->dev, "EC read failed: %d\n", error);
128		return error;
129	}
130	priv->msg_counter = RESP_COUNTER(response);
131
132	error = devm_request_threaded_irq(&spi->dev, spi->irq, NULL,
133					  ec_input_interrupt,
134					  IRQF_ONESHOT,
135					  "Ariel EC Input", priv);
136
137	if (error) {
138		dev_err(&spi->dev, "Failed to request IRQ %d: %d\n",
139			spi->irq, error);
140		return error;
141	}
142
143	return 0;
144}
145
146static const struct of_device_id ariel_pwrbutton_of_match[] = {
147	{ .compatible = "dell,wyse-ariel-ec-input" },
148	{ }
149};
150MODULE_DEVICE_TABLE(of, ariel_pwrbutton_of_match);
151
152static const struct spi_device_id ariel_pwrbutton_spi_ids[] = {
153	{ .name = "wyse-ariel-ec-input" },
154	{ }
155};
156MODULE_DEVICE_TABLE(spi, ariel_pwrbutton_spi_ids);
157
158static struct spi_driver ariel_pwrbutton_driver = {
159	.driver = {
160		.name = "dell-wyse-ariel-ec-input",
161		.of_match_table = ariel_pwrbutton_of_match,
162	},
163	.probe = ariel_pwrbutton_probe,
164	.id_table = ariel_pwrbutton_spi_ids,
165};
166module_spi_driver(ariel_pwrbutton_driver);
167
168MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
169MODULE_DESCRIPTION("Dell Wyse 3020 Power Button Input Driver");
170MODULE_LICENSE("Dual BSD/GPL");
171