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