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 
20 struct ec_input_response {
21 	u8 reserved;
22 	u8 header;
23 	u8 data[3];
24 } __packed;
25 
26 struct ariel_pwrbutton {
27 	struct spi_device *client;
28 	struct input_dev *input;
29 	u8 msg_counter;
30 };
31 
32 static 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 
49 static 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 
91 out:
92 	return IRQ_HANDLED;
93 }
94 
95 static 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 
146 static const struct of_device_id ariel_pwrbutton_of_match[] = {
147 	{ .compatible = "dell,wyse-ariel-ec-input" },
148 	{ }
149 };
150 MODULE_DEVICE_TABLE(of, ariel_pwrbutton_of_match);
151 
152 static struct spi_driver ariel_pwrbutton_driver = {
153 	.driver = {
154 		.name = "dell-wyse-ariel-ec-input",
155 		.of_match_table = ariel_pwrbutton_of_match,
156 	},
157 	.probe = ariel_pwrbutton_probe,
158 };
159 module_spi_driver(ariel_pwrbutton_driver);
160 
161 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
162 MODULE_DESCRIPTION("Dell Wyse 3020 Power Button Input Driver");
163 MODULE_LICENSE("Dual BSD/GPL");
164