1/*
  2 * Supports for the button array on the Surface tablets.
  3 *
  4 * (C) Copyright 2016 Red Hat, Inc
  5 *
  6 * Based on soc_button_array.c:
  7 *
  8 * {C} Copyright 2014 Intel Corporation
  9 *
 10 * This program is free software; you can redistribute it and/or
 11 * modify it under the terms of the GNU General Public License
 12 * as published by the Free Software Foundation; version 2
 13 * of the License.
 14 */
 15
 16#include <linux/module.h>
 17#include <linux/input.h>
 18#include <linux/init.h>
 19#include <linux/kernel.h>
 20#include <linux/i2c.h>
 21#include <linux/slab.h>
 22#include <linux/acpi.h>
 23#include <linux/gpio/consumer.h>
 24#include <linux/gpio_keys.h>
 25#include <linux/gpio.h>
 26#include <linux/platform_device.h>
 27
 28
 29#define SURFACE_BUTTON_OBJ_NAME		"TEV2"
 30#define MAX_NBUTTONS			4
 31
 32/*
 33 * Some of the buttons like volume up/down are auto repeat, while others
 34 * are not. To support both, we register two platform devices, and put
 35 * buttons into them based on whether the key should be auto repeat.
 36 */
 37#define BUTTON_TYPES			2
 38
 39/*
 40 * Power button, Home button, Volume buttons support is supposed to
 41 * be covered by drivers/input/misc/soc_button_array.c, which is implemented
 42 * according to "Windows ACPI Design Guide for SoC Platforms".
 43 * However surface 3 seems not to obey the specs, instead it uses
 44 * device TEV2(MSHW0028) for declaring the GPIOs. The gpios are also slightly
 45 * different in which the Home button is active high.
 46 * Compared to surfacepro3_button.c which also handles MSHW0028, the Surface 3
 47 * is a reduce platform and thus uses GPIOs, not ACPI events.
 48 * We choose an I2C driver here because we need to access the resources
 49 * declared under the device node, while surfacepro3_button.c only needs
 50 * the ACPI companion node.
 51 */
 52static const struct acpi_device_id surface3_acpi_match[] = {
 53	{ "MSHW0028", 0 },
 54	{ }
 55};
 56MODULE_DEVICE_TABLE(acpi, surface3_acpi_match);
 57
 58struct surface3_button_info {
 59	const char *name;
 60	int acpi_index;
 61	unsigned int event_type;
 62	unsigned int event_code;
 63	bool autorepeat;
 64	bool wakeup;
 65	bool active_low;
 66};
 67
 68struct surface3_button_data {
 69	struct platform_device *children[BUTTON_TYPES];
 70};
 71
 72/*
 73 * Get the Nth GPIO number from the ACPI object.
 74 */
 75static int surface3_button_lookup_gpio(struct device *dev, int acpi_index)
 76{
 77	struct gpio_desc *desc;
 78	int gpio;
 79
 80	desc = gpiod_get_index(dev, NULL, acpi_index, GPIOD_ASIS);
 81	if (IS_ERR(desc))
 82		return PTR_ERR(desc);
 83
 84	gpio = desc_to_gpio(desc);
 85
 86	gpiod_put(desc);
 87
 88	return gpio;
 89}
 90
 91static struct platform_device *
 92surface3_button_device_create(struct i2c_client *client,
 93			      const struct surface3_button_info *button_info,
 94			      bool autorepeat)
 95{
 96	const struct surface3_button_info *info;
 97	struct platform_device *pd;
 98	struct gpio_keys_button *gpio_keys;
 99	struct gpio_keys_platform_data *gpio_keys_pdata;
100	int n_buttons = 0;
101	int gpio;
102	int error;
103
104	gpio_keys_pdata = devm_kzalloc(&client->dev,
105				       sizeof(*gpio_keys_pdata) +
106				       sizeof(*gpio_keys) * MAX_NBUTTONS,
107				       GFP_KERNEL);
108	if (!gpio_keys_pdata)
109		return ERR_PTR(-ENOMEM);
110
111	gpio_keys = (void *)(gpio_keys_pdata + 1);
112
113	for (info = button_info; info->name; info++) {
114		if (info->autorepeat != autorepeat)
115			continue;
116
117		gpio = surface3_button_lookup_gpio(&client->dev,
118						   info->acpi_index);
119		if (!gpio_is_valid(gpio))
120			continue;
121
122		gpio_keys[n_buttons].type = info->event_type;
123		gpio_keys[n_buttons].code = info->event_code;
124		gpio_keys[n_buttons].gpio = gpio;
125		gpio_keys[n_buttons].active_low = info->active_low;
126		gpio_keys[n_buttons].desc = info->name;
127		gpio_keys[n_buttons].wakeup = info->wakeup;
128		n_buttons++;
129	}
130
131	if (n_buttons == 0) {
132		error = -ENODEV;
133		goto err_free_mem;
134	}
135
136	gpio_keys_pdata->buttons = gpio_keys;
137	gpio_keys_pdata->nbuttons = n_buttons;
138	gpio_keys_pdata->rep = autorepeat;
139
140	pd = platform_device_alloc("gpio-keys", PLATFORM_DEVID_AUTO);
141	if (!pd) {
142		error = -ENOMEM;
143		goto err_free_mem;
144	}
145
146	error = platform_device_add_data(pd, gpio_keys_pdata,
147					 sizeof(*gpio_keys_pdata));
148	if (error)
149		goto err_free_pdev;
150
151	error = platform_device_add(pd);
152	if (error)
153		goto err_free_pdev;
154
155	return pd;
156
157err_free_pdev:
158	platform_device_put(pd);
159err_free_mem:
160	devm_kfree(&client->dev, gpio_keys_pdata);
161	return ERR_PTR(error);
162}
163
164static int surface3_button_remove(struct i2c_client *client)
165{
166	struct surface3_button_data *priv = i2c_get_clientdata(client);
167
168	int i;
169
170	for (i = 0; i < BUTTON_TYPES; i++)
171		if (priv->children[i])
172			platform_device_unregister(priv->children[i]);
173
174	return 0;
175}
176
177static struct surface3_button_info surface3_button_surface3[] = {
178	{ "power", 0, EV_KEY, KEY_POWER, false, true, true },
179	{ "home", 1, EV_KEY, KEY_LEFTMETA, false, true, false },
180	{ "volume_up", 2, EV_KEY, KEY_VOLUMEUP, true, false, true },
181	{ "volume_down", 3, EV_KEY, KEY_VOLUMEDOWN, true, false, true },
182	{ }
183};
184
185static int surface3_button_probe(struct i2c_client *client,
186				 const struct i2c_device_id *id)
187{
188	struct device *dev = &client->dev;
189	struct surface3_button_data *priv;
190	struct platform_device *pd;
191	int i;
192	int error;
193
194	if (strncmp(acpi_device_bid(ACPI_COMPANION(&client->dev)),
195		    SURFACE_BUTTON_OBJ_NAME,
196		    strlen(SURFACE_BUTTON_OBJ_NAME)))
197		return -ENODEV;
198
199	error = gpiod_count(dev, NULL);
200	if (error < 0) {
201		dev_dbg(dev, "no GPIO attached, ignoring...\n");
202		return error;
203	}
204
205	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
206	if (!priv)
207		return -ENOMEM;
208
209	i2c_set_clientdata(client, priv);
210
211	for (i = 0; i < BUTTON_TYPES; i++) {
212		pd = surface3_button_device_create(client,
213						   surface3_button_surface3,
214						   i == 0);
215		if (IS_ERR(pd)) {
216			error = PTR_ERR(pd);
217			if (error != -ENODEV) {
218				surface3_button_remove(client);
219				return error;
220			}
221			continue;
222		}
223
224		priv->children[i] = pd;
225	}
226
227	if (!priv->children[0] && !priv->children[1])
228		return -ENODEV;
229
230	return 0;
231}
232
233static const struct i2c_device_id surface3_id[] = {
234	{ }
235};
236MODULE_DEVICE_TABLE(i2c, surface3_id);
237
238static struct i2c_driver surface3_driver = {
239	.probe = surface3_button_probe,
240	.remove = surface3_button_remove,
241	.id_table = surface3_id,
242	.driver = {
243		.name = "surface3",
244		.acpi_match_table = ACPI_PTR(surface3_acpi_match),
245	},
246};
247module_i2c_driver(surface3_driver);
248
249MODULE_AUTHOR("Benjamin Tissoires <benjamin.tissoires@gmail.com>");
250MODULE_DESCRIPTION("surface3 button array driver");
251MODULE_LICENSE("GPL v2");