1/*
  2 * Supports for the button array on SoC tablets originally running
  3 * Windows 8.
  4 *
  5 * (C) Copyright 2014 Intel Corporation
  6 *
  7 * This program is free software; you can redistribute it and/or
  8 * modify it under the terms of the GNU General Public License
  9 * as published by the Free Software Foundation; version 2
 10 * of the License.
 11 */
 12
 13#include <linux/module.h>
 14#include <linux/input.h>
 15#include <linux/init.h>
 16#include <linux/kernel.h>
 17#include <linux/acpi.h>
 18#include <linux/gpio/consumer.h>
 19#include <linux/gpio_keys.h>
 20#include <linux/platform_device.h>
 21
 22/*
 23 * Definition of buttons on the tablet. The ACPI index of each button
 24 * is defined in section 2.8.7.2 of "Windows ACPI Design Guide for SoC
 25 * Platforms"
 26 */
 27#define MAX_NBUTTONS	5
 28
 29struct soc_button_info {
 30	const char *name;
 31	int acpi_index;
 32	unsigned int event_type;
 33	unsigned int event_code;
 34	bool autorepeat;
 35	bool wakeup;
 36};
 37
 38/*
 39 * Some of the buttons like volume up/down are auto repeat, while others
 40 * are not. To support both, we register two platform devices, and put
 41 * buttons into them based on whether the key should be auto repeat.
 42 */
 43#define BUTTON_TYPES	2
 44
 45struct soc_button_data {
 46	struct platform_device *children[BUTTON_TYPES];
 47};
 48
 49/*
 50 * Get the Nth GPIO number from the ACPI object.
 51 */
 52static int soc_button_lookup_gpio(struct device *dev, int acpi_index)
 53{
 54	struct gpio_desc *desc;
 55	int gpio;
 56
 57	desc = gpiod_get_index(dev, KBUILD_MODNAME, acpi_index, GPIOD_ASIS);
 58	if (IS_ERR(desc))
 59		return PTR_ERR(desc);
 60
 61	gpio = desc_to_gpio(desc);
 62
 63	gpiod_put(desc);
 64
 65	return gpio;
 66}
 67
 68static struct platform_device *
 69soc_button_device_create(struct platform_device *pdev,
 70			 const struct soc_button_info *button_info,
 71			 bool autorepeat)
 72{
 73	const struct soc_button_info *info;
 74	struct platform_device *pd;
 75	struct gpio_keys_button *gpio_keys;
 76	struct gpio_keys_platform_data *gpio_keys_pdata;
 77	int n_buttons = 0;
 78	int gpio;
 79	int error;
 80
 81	gpio_keys_pdata = devm_kzalloc(&pdev->dev,
 82				       sizeof(*gpio_keys_pdata) +
 83					sizeof(*gpio_keys) * MAX_NBUTTONS,
 84				       GFP_KERNEL);
 85	if (!gpio_keys_pdata)
 86		return ERR_PTR(-ENOMEM);
 87
 88	gpio_keys = (void *)(gpio_keys_pdata + 1);
 89
 90	for (info = button_info; info->name; info++) {
 91		if (info->autorepeat != autorepeat)
 92			continue;
 93
 94		gpio = soc_button_lookup_gpio(&pdev->dev, info->acpi_index);
 95		if (gpio < 0)
 96			continue;
 97
 98		gpio_keys[n_buttons].type = info->event_type;
 99		gpio_keys[n_buttons].code = info->event_code;
100		gpio_keys[n_buttons].gpio = gpio;
101		gpio_keys[n_buttons].active_low = 1;
102		gpio_keys[n_buttons].desc = info->name;
103		gpio_keys[n_buttons].wakeup = info->wakeup;
104		n_buttons++;
105	}
106
107	if (n_buttons == 0) {
108		error = -ENODEV;
109		goto err_free_mem;
110	}
111
112	gpio_keys_pdata->buttons = gpio_keys;
113	gpio_keys_pdata->nbuttons = n_buttons;
114	gpio_keys_pdata->rep = autorepeat;
115
116	pd = platform_device_alloc("gpio-keys", PLATFORM_DEVID_AUTO);
117	if (!pd) {
118		error = -ENOMEM;
119		goto err_free_mem;
120	}
121
122	error = platform_device_add_data(pd, gpio_keys_pdata,
123					 sizeof(*gpio_keys_pdata));
124	if (error)
125		goto err_free_pdev;
126
127	error = platform_device_add(pd);
128	if (error)
129		goto err_free_pdev;
130
131	return pd;
132
133err_free_pdev:
134	platform_device_put(pd);
135err_free_mem:
136	devm_kfree(&pdev->dev, gpio_keys_pdata);
137	return ERR_PTR(error);
138}
139
140static int soc_button_remove(struct platform_device *pdev)
141{
142	struct soc_button_data *priv = platform_get_drvdata(pdev);
143
144	int i;
145
146	for (i = 0; i < BUTTON_TYPES; i++)
147		if (priv->children[i])
148			platform_device_unregister(priv->children[i]);
149
150	return 0;
151}
152
153static int soc_button_probe(struct platform_device *pdev)
154{
155	struct device *dev = &pdev->dev;
156	const struct acpi_device_id *id;
157	struct soc_button_info *button_info;
158	struct soc_button_data *priv;
159	struct platform_device *pd;
160	int i;
161	int error;
162
163	id = acpi_match_device(dev->driver->acpi_match_table, dev);
164	if (!id)
165		return -ENODEV;
166
167	button_info = (struct soc_button_info *)id->driver_data;
168
169	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
170	if (!priv)
171		return -ENOMEM;
172
173	platform_set_drvdata(pdev, priv);
174
175	for (i = 0; i < BUTTON_TYPES; i++) {
176		pd = soc_button_device_create(pdev, button_info, i == 0);
177		if (IS_ERR(pd)) {
178			error = PTR_ERR(pd);
179			if (error != -ENODEV) {
180				soc_button_remove(pdev);
181				return error;
182			}
183			continue;
184		}
185
186		priv->children[i] = pd;
187	}
188
189	if (!priv->children[0] && !priv->children[1])
190		return -ENODEV;
191
192	return 0;
193}
194
195static struct soc_button_info soc_button_PNP0C40[] = {
196	{ "power", 0, EV_KEY, KEY_POWER, false, true },
197	{ "home", 1, EV_KEY, KEY_LEFTMETA, false, true },
198	{ "volume_up", 2, EV_KEY, KEY_VOLUMEUP, true, false },
199	{ "volume_down", 3, EV_KEY, KEY_VOLUMEDOWN, true, false },
200	{ "rotation_lock", 4, EV_SW, SW_ROTATE_LOCK, false, false },
201	{ }
202};
203
204static const struct acpi_device_id soc_button_acpi_match[] = {
205	{ "PNP0C40", (unsigned long)soc_button_PNP0C40 },
206	{ }
207};
208
209MODULE_DEVICE_TABLE(acpi, soc_button_acpi_match);
210
211static struct platform_driver soc_button_driver = {
212	.probe          = soc_button_probe,
213	.remove		= soc_button_remove,
214	.driver		= {
215		.name = KBUILD_MODNAME,
216		.acpi_match_table = ACPI_PTR(soc_button_acpi_match),
217	},
218};
219module_platform_driver(soc_button_driver);
220
221MODULE_LICENSE("GPL");