1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Supports for the button array on the Surface tablets.
  4 *
  5 * (C) Copyright 2016 Red Hat, Inc
  6 *
  7 * Based on soc_button_array.c:
  8 *
  9 * {C} Copyright 2014 Intel Corporation
 10 */
 11
 12#include <linux/module.h>
 13#include <linux/input.h>
 14#include <linux/init.h>
 15#include <linux/kernel.h>
 16#include <linux/i2c.h>
 17#include <linux/slab.h>
 18#include <linux/acpi.h>
 19#include <linux/gpio/consumer.h>
 20#include <linux/gpio_keys.h>
 21#include <linux/gpio.h>
 22#include <linux/platform_device.h>
 23
 24
 25#define SURFACE_BUTTON_OBJ_NAME		"TEV2"
 26#define MAX_NBUTTONS			4
 27
 28/*
 29 * Some of the buttons like volume up/down are auto repeat, while others
 30 * are not. To support both, we register two platform devices, and put
 31 * buttons into them based on whether the key should be auto repeat.
 32 */
 33#define BUTTON_TYPES			2
 34
 35/*
 36 * Power button, Home button, Volume buttons support is supposed to
 37 * be covered by drivers/input/misc/soc_button_array.c, which is implemented
 38 * according to "Windows ACPI Design Guide for SoC Platforms".
 39 * However surface 3 seems not to obey the specs, instead it uses
 40 * device TEV2(MSHW0028) for declaring the GPIOs. The gpios are also slightly
 41 * different in which the Home button is active high.
 42 * Compared to surfacepro3_button.c which also handles MSHW0028, the Surface 3
 43 * is a reduce platform and thus uses GPIOs, not ACPI events.
 44 * We choose an I2C driver here because we need to access the resources
 45 * declared under the device node, while surfacepro3_button.c only needs
 46 * the ACPI companion node.
 47 */
 48static const struct acpi_device_id surface3_acpi_match[] = {
 49	{ "MSHW0028", 0 },
 50	{ }
 51};
 52MODULE_DEVICE_TABLE(acpi, surface3_acpi_match);
 53
 54struct surface3_button_info {
 55	const char *name;
 56	int acpi_index;
 57	unsigned int event_type;
 58	unsigned int event_code;
 59	bool autorepeat;
 60	bool wakeup;
 61	bool active_low;
 62};
 63
 64struct surface3_button_data {
 65	struct platform_device *children[BUTTON_TYPES];
 66};
 67
 68/*
 69 * Get the Nth GPIO number from the ACPI object.
 70 */
 71static int surface3_button_lookup_gpio(struct device *dev, int acpi_index)
 72{
 73	struct gpio_desc *desc;
 74	int gpio;
 75
 76	desc = gpiod_get_index(dev, NULL, acpi_index, GPIOD_ASIS);
 77	if (IS_ERR(desc))
 78		return PTR_ERR(desc);
 79
 80	gpio = desc_to_gpio(desc);
 81
 82	gpiod_put(desc);
 83
 84	return gpio;
 85}
 86
 87static struct platform_device *
 88surface3_button_device_create(struct i2c_client *client,
 89			      const struct surface3_button_info *button_info,
 90			      bool autorepeat)
 91{
 92	const struct surface3_button_info *info;
 93	struct platform_device *pd;
 94	struct gpio_keys_button *gpio_keys;
 95	struct gpio_keys_platform_data *gpio_keys_pdata;
 96	int n_buttons = 0;
 97	int gpio;
 98	int error;
 99
100	gpio_keys_pdata = devm_kzalloc(&client->dev,
101				       sizeof(*gpio_keys_pdata) +
102				       sizeof(*gpio_keys) * MAX_NBUTTONS,
103				       GFP_KERNEL);
104	if (!gpio_keys_pdata)
105		return ERR_PTR(-ENOMEM);
106
107	gpio_keys = (void *)(gpio_keys_pdata + 1);
108
109	for (info = button_info; info->name; info++) {
110		if (info->autorepeat != autorepeat)
111			continue;
112
113		gpio = surface3_button_lookup_gpio(&client->dev,
114						   info->acpi_index);
115		if (!gpio_is_valid(gpio))
116			continue;
117
118		gpio_keys[n_buttons].type = info->event_type;
119		gpio_keys[n_buttons].code = info->event_code;
120		gpio_keys[n_buttons].gpio = gpio;
121		gpio_keys[n_buttons].active_low = info->active_low;
122		gpio_keys[n_buttons].desc = info->name;
123		gpio_keys[n_buttons].wakeup = info->wakeup;
124		n_buttons++;
125	}
126
127	if (n_buttons == 0) {
128		error = -ENODEV;
129		goto err_free_mem;
130	}
131
132	gpio_keys_pdata->buttons = gpio_keys;
133	gpio_keys_pdata->nbuttons = n_buttons;
134	gpio_keys_pdata->rep = autorepeat;
135
136	pd = platform_device_alloc("gpio-keys", PLATFORM_DEVID_AUTO);
137	if (!pd) {
138		error = -ENOMEM;
139		goto err_free_mem;
140	}
141
142	error = platform_device_add_data(pd, gpio_keys_pdata,
143					 sizeof(*gpio_keys_pdata));
144	if (error)
145		goto err_free_pdev;
146
147	error = platform_device_add(pd);
148	if (error)
149		goto err_free_pdev;
150
151	return pd;
152
153err_free_pdev:
154	platform_device_put(pd);
155err_free_mem:
156	devm_kfree(&client->dev, gpio_keys_pdata);
157	return ERR_PTR(error);
158}
159
160static int surface3_button_remove(struct i2c_client *client)
161{
162	struct surface3_button_data *priv = i2c_get_clientdata(client);
163
164	int i;
165
166	for (i = 0; i < BUTTON_TYPES; i++)
167		if (priv->children[i])
168			platform_device_unregister(priv->children[i]);
169
170	return 0;
171}
172
173static struct surface3_button_info surface3_button_surface3[] = {
174	{ "power", 0, EV_KEY, KEY_POWER, false, true, true },
175	{ "home", 1, EV_KEY, KEY_LEFTMETA, false, true, false },
176	{ "volume_up", 2, EV_KEY, KEY_VOLUMEUP, true, false, true },
177	{ "volume_down", 3, EV_KEY, KEY_VOLUMEDOWN, true, false, true },
178	{ }
179};
180
181static int surface3_button_probe(struct i2c_client *client,
182				 const struct i2c_device_id *id)
183{
184	struct device *dev = &client->dev;
185	struct surface3_button_data *priv;
186	struct platform_device *pd;
187	int i;
188	int error;
189
190	if (strncmp(acpi_device_bid(ACPI_COMPANION(&client->dev)),
191		    SURFACE_BUTTON_OBJ_NAME,
192		    strlen(SURFACE_BUTTON_OBJ_NAME)))
193		return -ENODEV;
194
195	error = gpiod_count(dev, NULL);
196	if (error < 0) {
197		dev_dbg(dev, "no GPIO attached, ignoring...\n");
198		return error;
199	}
200
201	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
202	if (!priv)
203		return -ENOMEM;
204
205	i2c_set_clientdata(client, priv);
206
207	for (i = 0; i < BUTTON_TYPES; i++) {
208		pd = surface3_button_device_create(client,
209						   surface3_button_surface3,
210						   i == 0);
211		if (IS_ERR(pd)) {
212			error = PTR_ERR(pd);
213			if (error != -ENODEV) {
214				surface3_button_remove(client);
215				return error;
216			}
217			continue;
218		}
219
220		priv->children[i] = pd;
221	}
222
223	if (!priv->children[0] && !priv->children[1])
224		return -ENODEV;
225
226	return 0;
227}
228
229static const struct i2c_device_id surface3_id[] = {
230	{ }
231};
232MODULE_DEVICE_TABLE(i2c, surface3_id);
233
234static struct i2c_driver surface3_driver = {
235	.probe = surface3_button_probe,
236	.remove = surface3_button_remove,
237	.id_table = surface3_id,
238	.driver = {
239		.name = "surface3",
240		.acpi_match_table = ACPI_PTR(surface3_acpi_match),
241	},
242};
243module_i2c_driver(surface3_driver);
244
245MODULE_AUTHOR("Benjamin Tissoires <benjamin.tissoires@gmail.com>");
246MODULE_DESCRIPTION("surface3 button array driver");
247MODULE_LICENSE("GPL v2");