[GitHub/mt8127/android_kernel_alcatel_ttab.git] / drivers / i2c / i2c-smbus.c

/*
 * i2c-smbus.c - SMBus extensions to the I2C protocol
 *
 * Copyright (C) 2008 David Brownell
 * Copyright (C) 2010 Jean Delvare <khali@linux-fr.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301 USA.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/interrupt.h>
#include <linux/workqueue.h>
#include <linux/i2c.h>
#include <linux/i2c-smbus.h>
#include <linux/slab.h>

struct i2c_smbus_alert {
	unsigned int		alert_edge_triggered:1;
	int			irq;
	struct work_struct	alert;
	struct i2c_client	*ara;		/* Alert response address */
};

struct alert_data {
	unsigned short		addr;
	u8			flag:1;
};

/* If this is the alerting device, notify its driver */
static int smbus_do_alert(struct device *dev, void *addrp)
{
	struct i2c_client *client = i2c_verify_client(dev);
	struct alert_data *data = addrp;

	if (!client || client->addr != data->addr)
		return 0;
	if (client->flags & I2C_CLIENT_TEN)
		return 0;

	/*
	 * Drivers should either disable alerts, or provide at least
	 * a minimal handler.  Lock so client->driver won't change.
	 */
	device_lock(dev);
	if (client->driver) {
		if (client->driver->alert)
			client->driver->alert(client, data->flag);
		else
			dev_warn(&client->dev, "no driver alert()!\n");
	} else
		dev_dbg(&client->dev, "alert with no driver\n");
	device_unlock(dev);

	/* Stop iterating after we find the device */
	return -EBUSY;
}

/*
 * The alert IRQ handler needs to hand work off to a task which can issue
 * SMBus calls, because those sleeping calls can't be made in IRQ context.
 */
static void smbus_alert(struct work_struct *work)
{
	struct i2c_smbus_alert *alert;
	struct i2c_client *ara;
	unsigned short prev_addr = 0;	/* Not a valid address */

	alert = container_of(work, struct i2c_smbus_alert, alert);
	ara = alert->ara;

	for (;;) {
		s32 status;
		struct alert_data data;

		/*
		 * Devices with pending alerts reply in address order, low
		 * to high, because of slave transmit arbitration.  After
		 * responding, an SMBus device stops asserting SMBALERT#.
		 *
		 * Note that SMBus 2.0 reserves 10-bit addresess for future
		 * use.  We neither handle them, nor try to use PEC here.
		 */
		status = i2c_smbus_read_byte(ara);
		if (status < 0)
			break;

		data.flag = status & 1;
		data.addr = status >> 1;

		if (data.addr == prev_addr) {
			dev_warn(&ara->dev, "Duplicate SMBALERT# from dev "
				"0x%02x, skipping\n", data.addr);
			break;
		}
		dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n",
			data.addr, data.flag);

		/* Notify driver for the device which issued the alert */
		device_for_each_child(&ara->adapter->dev, &data,
				      smbus_do_alert);
		prev_addr = data.addr;
	}

	/* We handled all alerts; re-enable level-triggered IRQs */
	if (!alert->alert_edge_triggered)
		enable_irq(alert->irq);
}

static irqreturn_t smbalert_irq(int irq, void *d)
{
	struct i2c_smbus_alert *alert = d;

	/* Disable level-triggered IRQs until we handle them */
	if (!alert->alert_edge_triggered)
		disable_irq_nosync(irq);

	schedule_work(&alert->alert);
	return IRQ_HANDLED;
}

/* Setup SMBALERT# infrastructure */
static int smbalert_probe(struct i2c_client *ara,
			  const struct i2c_device_id *id)
{
	struct i2c_smbus_alert_setup *setup = ara->dev.platform_data;
	struct i2c_smbus_alert *alert;
	struct i2c_adapter *adapter = ara->adapter;
	int res;

	alert = devm_kzalloc(&ara->dev, sizeof(struct i2c_smbus_alert),
			     GFP_KERNEL);
	if (!alert)
		return -ENOMEM;

	alert->alert_edge_triggered = setup->alert_edge_triggered;
	alert->irq = setup->irq;
	INIT_WORK(&alert->alert, smbus_alert);
	alert->ara = ara;

	if (setup->irq > 0) {
		res = devm_request_irq(&ara->dev, setup->irq, smbalert_irq,
				       0, "smbus_alert", alert);
		if (res)
			return res;
	}

	i2c_set_clientdata(ara, alert);
	dev_info(&adapter->dev, "supports SMBALERT#, %s trigger\n",
		 setup->alert_edge_triggered ? "edge" : "level");

	return 0;
}

/* IRQ and memory resources are managed so they are freed automatically */
static int smbalert_remove(struct i2c_client *ara)
{
	struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);

	cancel_work_sync(&alert->alert);
	return 0;
}

static const struct i2c_device_id smbalert_ids[] = {
	{ "smbus_alert", 0 },
	{ /* LIST END */ }
};
MODULE_DEVICE_TABLE(i2c, smbalert_ids);

static struct i2c_driver smbalert_driver = {
	.driver = {
		.name	= "smbus_alert",
	},
	.probe		= smbalert_probe,
	.remove		= smbalert_remove,
	.id_table	= smbalert_ids,
};

/**
 * i2c_setup_smbus_alert - Setup SMBus alert support
 * @adapter: the target adapter
 * @setup: setup data for the SMBus alert handler
 * Context: can sleep
 *
 * Setup handling of the SMBus alert protocol on a given I2C bus segment.
 *
 * Handling can be done either through our IRQ handler, or by the
 * adapter (from its handler, periodic polling, or whatever).
 *
 * NOTE that if we manage the IRQ, we *MUST* know if it's level or
 * edge triggered in order to hand it to the workqueue correctly.
 * If triggering the alert seems to wedge the system, you probably
 * should have said it's level triggered.
 *
 * This returns the ara client, which should be saved for later use with
 * i2c_handle_smbus_alert() and ultimately i2c_unregister_device(); or NULL
 * to indicate an error.
 */
struct i2c_client *i2c_setup_smbus_alert(struct i2c_adapter *adapter,
					 struct i2c_smbus_alert_setup *setup)
{
	struct i2c_board_info ara_board_info = {
		I2C_BOARD_INFO("smbus_alert", 0x0c),
		.platform_data = setup,
	};

	return i2c_new_device(adapter, &ara_board_info);
}
EXPORT_SYMBOL_GPL(i2c_setup_smbus_alert);

/**
 * i2c_handle_smbus_alert - Handle an SMBus alert
 * @ara: the ARA client on the relevant adapter
 * Context: can't sleep
 *
 * Helper function to be called from an I2C bus driver's interrupt
 * handler. It will schedule the alert work, in turn calling the
 * corresponding I2C device driver's alert function.
 *
 * It is assumed that ara is a valid i2c client previously returned by
 * i2c_setup_smbus_alert().
 */
int i2c_handle_smbus_alert(struct i2c_client *ara)
{
	struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);

	return schedule_work(&alert->alert);
}
EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert);

module_i2c_driver(smbalert_driver);

MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
MODULE_DESCRIPTION("SMBus protocol extensions support");
MODULE_LICENSE("GPL");
Commit	Line	Data
b5527a77 JD	1	/*
	2	* i2c-smbus.c - SMBus extensions to the I2C protocol
	3	*
	4	* Copyright (C) 2008 David Brownell
	5	* Copyright (C) 2010 Jean Delvare <khali@linux-fr.org>
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License as published by
	9	* the Free Software Foundation; either version 2 of the License, or
	10	* (at your option) any later version.
	11	*
	12	* This program is distributed in the hope that it will be useful,
	13	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	15	* GNU General Public License for more details.
	16	*
	17	* You should have received a copy of the GNU General Public License
	18	* along with this program; if not, write to the Free Software
5694f8a8 JD	19	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
5694f8a8 JD	20	* MA 02110-1301 USA.
b5527a77 JD	21	*/
	22
	23	#include <linux/kernel.h>
	24	#include <linux/module.h>
	25	#include <linux/device.h>
b5527a77 JD	26	#include <linux/interrupt.h>
	27	#include <linux/workqueue.h>
	28	#include <linux/i2c.h>
	29	#include <linux/i2c-smbus.h>
5a0e3ad6	30	#include <linux/slab.h>
b5527a77 JD	31
	32	struct i2c_smbus_alert {
	33	unsigned int alert_edge_triggered:1;
	34	int irq;
	35	struct work_struct alert;
	36	struct i2c_client ara; / Alert response address */
	37	};
	38
	39	struct alert_data {
	40	unsigned short addr;
	41	u8 flag:1;
	42	};
	43
	44	/* If this is the alerting device, notify its driver */
	45	static int smbus_do_alert(struct device dev, void addrp)
	46	{
	47	struct i2c_client *client = i2c_verify_client(dev);
	48	struct alert_data *data = addrp;
	49
	50	if (!client \|\| client->addr != data->addr)
	51	return 0;
	52	if (client->flags & I2C_CLIENT_TEN)
	53	return 0;
	54
	55	/*
	56	* Drivers should either disable alerts, or provide at least
	57	* a minimal handler. Lock so client->driver won't change.
	58	*/
f635a1e7	59	device_lock(dev);
b5527a77 JD	60	if (client->driver) {
	61	if (client->driver->alert)
	62	client->driver->alert(client, data->flag);
	63	else
	64	dev_warn(&client->dev, "no driver alert()!\n");
	65	} else
	66	dev_dbg(&client->dev, "alert with no driver\n");
f635a1e7	67	device_unlock(dev);
b5527a77 JD	68
	69	/* Stop iterating after we find the device */
	70	return -EBUSY;
	71	}
	72
	73	/*
	74	* The alert IRQ handler needs to hand work off to a task which can issue
	75	* SMBus calls, because those sleeping calls can't be made in IRQ context.
	76	*/
	77	static void smbus_alert(struct work_struct *work)
	78	{
	79	struct i2c_smbus_alert *alert;
	80	struct i2c_client *ara;
	81	unsigned short prev_addr = 0; /* Not a valid address */
	82
	83	alert = container_of(work, struct i2c_smbus_alert, alert);
	84	ara = alert->ara;
	85
	86	for (;;) {
	87	s32 status;
	88	struct alert_data data;
	89
	90	/*
	91	* Devices with pending alerts reply in address order, low
	92	* to high, because of slave transmit arbitration. After
	93	* responding, an SMBus device stops asserting SMBALERT#.
	94	*
	95	* Note that SMBus 2.0 reserves 10-bit addresess for future
	96	* use. We neither handle them, nor try to use PEC here.
	97	*/
	98	status = i2c_smbus_read_byte(ara);
	99	if (status < 0)
	100	break;
	101
	102	data.flag = status & 1;
	103	data.addr = status >> 1;
	104
	105	if (data.addr == prev_addr) {
	106	dev_warn(&ara->dev, "Duplicate SMBALERT# from dev "
	107	"0x%02x, skipping\n", data.addr);
	108	break;
	109	}
	110	dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n",
	111	data.addr, data.flag);
	112
	113	/* Notify driver for the device which issued the alert */
	114	device_for_each_child(&ara->adapter->dev, &data,
	115	smbus_do_alert);
	116	prev_addr = data.addr;
	117	}
	118
	119	/* We handled all alerts; re-enable level-triggered IRQs */
	120	if (!alert->alert_edge_triggered)
	121	enable_irq(alert->irq);
	122	}
	123
	124	static irqreturn_t smbalert_irq(int irq, void *d)
	125	{
	126	struct i2c_smbus_alert *alert = d;
	127
	128	/* Disable level-triggered IRQs until we handle them */
	129	if (!alert->alert_edge_triggered)
	130	disable_irq_nosync(irq);
	131
132	schedule_work(&alert->alert);
133	return IRQ_HANDLED;
134	}
135
136	/* Setup SMBALERT# infrastructure */
137	static int smbalert_probe(struct i2c_client *ara,
138	const struct i2c_device_id *id)
139	{
140	struct i2c_smbus_alert_setup *setup = ara->dev.platform_data;
141	struct i2c_smbus_alert *alert;
142	struct i2c_adapter *adapter = ara->adapter;
143	int res;
144
71b57845 JL	145	alert = devm_kzalloc(&ara->dev, sizeof(struct i2c_smbus_alert),
71b57845 JL	146	GFP_KERNEL);
b5527a77 JD	147	if (!alert)
	148	return -ENOMEM;
	149
	150	alert->alert_edge_triggered = setup->alert_edge_triggered;
	151	alert->irq = setup->irq;
	152	INIT_WORK(&alert->alert, smbus_alert);
	153	alert->ara = ara;
	154
	155	if (setup->irq > 0) {
	156	res = devm_request_irq(&ara->dev, setup->irq, smbalert_irq,
	157	0, "smbus_alert", alert);
71b57845	158	if (res)
b5527a77	159	return res;
b5527a77 JD	160	}
	161
	162	i2c_set_clientdata(ara, alert);
	163	dev_info(&adapter->dev, "supports SMBALERT#, %s trigger\n",
	164	setup->alert_edge_triggered ? "edge" : "level");
	165
	166	return 0;
	167	}
	168
71b57845	169	/* IRQ and memory resources are managed so they are freed automatically */
b5527a77 JD	170	static int smbalert_remove(struct i2c_client *ara)
	171	{
	172	struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
	173
	174	cancel_work_sync(&alert->alert);
b5527a77 JD	175	return 0;
	176	}
	177
	178	static const struct i2c_device_id smbalert_ids[] = {
	179	{ "smbus_alert", 0 },
	180	{ /* LIST END */ }
	181	};
	182	MODULE_DEVICE_TABLE(i2c, smbalert_ids);
	183
	184	static struct i2c_driver smbalert_driver = {
	185	.driver = {
	186	.name = "smbus_alert",
	187	},
	188	.probe = smbalert_probe,
	189	.remove = smbalert_remove,
	190	.id_table = smbalert_ids,
	191	};
	192
	193	/**
	194	* i2c_setup_smbus_alert - Setup SMBus alert support
	195	* @adapter: the target adapter
	196	* @setup: setup data for the SMBus alert handler
	197	* Context: can sleep
	198	*
	199	* Setup handling of the SMBus alert protocol on a given I2C bus segment.
	200	*
	201	* Handling can be done either through our IRQ handler, or by the
	202	* adapter (from its handler, periodic polling, or whatever).
	203	*
	204	* NOTE that if we manage the IRQ, we MUST know if it's level or
	205	* edge triggered in order to hand it to the workqueue correctly.
	206	* If triggering the alert seems to wedge the system, you probably
	207	* should have said it's level triggered.
	208	*
	209	* This returns the ara client, which should be saved for later use with
	210	* i2c_handle_smbus_alert() and ultimately i2c_unregister_device(); or NULL
	211	* to indicate an error.
	212	*/
	213	struct i2c_client i2c_setup_smbus_alert(struct i2c_adapter adapter,
	214	struct i2c_smbus_alert_setup *setup)
	215	{
	216	struct i2c_board_info ara_board_info = {
	217	I2C_BOARD_INFO("smbus_alert", 0x0c),
	218	.platform_data = setup,
	219	};
	220
	221	return i2c_new_device(adapter, &ara_board_info);
	222	}
	223	EXPORT_SYMBOL_GPL(i2c_setup_smbus_alert);
	224
	225	/**
	226	* i2c_handle_smbus_alert - Handle an SMBus alert
	227	* @ara: the ARA client on the relevant adapter
	228	* Context: can't sleep
	229	*
	230	* Helper function to be called from an I2C bus driver's interrupt
	231	* handler. It will schedule the alert work, in turn calling the
	232	* corresponding I2C device driver's alert function.
	233	*
	234	* It is assumed that ara is a valid i2c client previously returned by
	235	* i2c_setup_smbus_alert().
	236	*/
	237	int i2c_handle_smbus_alert(struct i2c_client *ara)
	238	{
239	struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
240
241	return schedule_work(&alert->alert);
242	}
243	EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert);
244
fda2f4af	245	module_i2c_driver(smbalert_driver);
b5527a77 JD	246
	247	MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
	248	MODULE_DESCRIPTION("SMBus protocol extensions support");
	249	MODULE_LICENSE("GPL");