[net-next-2.6.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., 675 Mass Ave, Cambridge, MA 02139, 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 = kzalloc(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) {
			kfree(alert);
			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 resource is managed so it is freed automatically */
static int smbalert_remove(struct i2c_client *ara)
{
	struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);

	cancel_work_sync(&alert->alert);

	kfree(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);

static int __init i2c_smbus_init(void)
{
	return i2c_add_driver(&smbalert_driver);
}

static void __exit i2c_smbus_exit(void)
{
	i2c_del_driver(&smbalert_driver);
}

module_init(i2c_smbus_init);
module_exit(i2c_smbus_exit);

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
	19	* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	20	*/
	21
	22	#include <linux/kernel.h>
	23	#include <linux/module.h>
	24	#include <linux/device.h>
b5527a77 JD	25	#include <linux/interrupt.h>
	26	#include <linux/workqueue.h>
	27	#include <linux/i2c.h>
	28	#include <linux/i2c-smbus.h>
5a0e3ad6	29	#include <linux/slab.h>
b5527a77 JD	30
	31	struct i2c_smbus_alert {
	32	unsigned int alert_edge_triggered:1;
	33	int irq;
	34	struct work_struct alert;
	35	struct i2c_client ara; / Alert response address */
	36	};
	37
	38	struct alert_data {
	39	unsigned short addr;
	40	u8 flag:1;
	41	};
	42
	43	/* If this is the alerting device, notify its driver */
	44	static int smbus_do_alert(struct device dev, void addrp)
	45	{
	46	struct i2c_client *client = i2c_verify_client(dev);
	47	struct alert_data *data = addrp;
	48
	49	if (!client \|\| client->addr != data->addr)
	50	return 0;
	51	if (client->flags & I2C_CLIENT_TEN)
	52	return 0;
	53
	54	/*
	55	* Drivers should either disable alerts, or provide at least
	56	* a minimal handler. Lock so client->driver won't change.
	57	*/
f635a1e7	58	device_lock(dev);
b5527a77 JD	59	if (client->driver) {
	60	if (client->driver->alert)
	61	client->driver->alert(client, data->flag);
	62	else
	63	dev_warn(&client->dev, "no driver alert()!\n");
	64	} else
	65	dev_dbg(&client->dev, "alert with no driver\n");
f635a1e7	66	device_unlock(dev);
b5527a77 JD	67
	68	/* Stop iterating after we find the device */
	69	return -EBUSY;
	70	}
	71
	72	/*
	73	* The alert IRQ handler needs to hand work off to a task which can issue
	74	* SMBus calls, because those sleeping calls can't be made in IRQ context.
	75	*/
	76	static void smbus_alert(struct work_struct *work)
	77	{
	78	struct i2c_smbus_alert *alert;
	79	struct i2c_client *ara;
	80	unsigned short prev_addr = 0; /* Not a valid address */
	81
	82	alert = container_of(work, struct i2c_smbus_alert, alert);
	83	ara = alert->ara;
	84
	85	for (;;) {
	86	s32 status;
	87	struct alert_data data;
	88
	89	/*
	90	* Devices with pending alerts reply in address order, low
	91	* to high, because of slave transmit arbitration. After
	92	* responding, an SMBus device stops asserting SMBALERT#.
	93	*
	94	* Note that SMBus 2.0 reserves 10-bit addresess for future
	95	* use. We neither handle them, nor try to use PEC here.
	96	*/
	97	status = i2c_smbus_read_byte(ara);
	98	if (status < 0)
	99	break;
	100
	101	data.flag = status & 1;
	102	data.addr = status >> 1;
	103
	104	if (data.addr == prev_addr) {
	105	dev_warn(&ara->dev, "Duplicate SMBALERT# from dev "
	106	"0x%02x, skipping\n", data.addr);
	107	break;
	108	}
	109	dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n",
	110	data.addr, data.flag);
	111
	112	/* Notify driver for the device which issued the alert */
	113	device_for_each_child(&ara->adapter->dev, &data,
	114	smbus_do_alert);
	115	prev_addr = data.addr;
	116	}
	117
	118	/* We handled all alerts; re-enable level-triggered IRQs */
	119	if (!alert->alert_edge_triggered)
	120	enable_irq(alert->irq);
	121	}
	122
	123	static irqreturn_t smbalert_irq(int irq, void *d)
	124	{
	125	struct i2c_smbus_alert *alert = d;
	126
	127	/* Disable level-triggered IRQs until we handle them */
	128	if (!alert->alert_edge_triggered)
	129	disable_irq_nosync(irq);
	130
131	schedule_work(&alert->alert);
132	return IRQ_HANDLED;
133	}
134
135	/* Setup SMBALERT# infrastructure */
136	static int smbalert_probe(struct i2c_client *ara,
137	const struct i2c_device_id *id)
138	{
139	struct i2c_smbus_alert_setup *setup = ara->dev.platform_data;
140	struct i2c_smbus_alert *alert;
141	struct i2c_adapter *adapter = ara->adapter;
142	int res;
143
144	alert = kzalloc(sizeof(struct i2c_smbus_alert), GFP_KERNEL);
145	if (!alert)
146	return -ENOMEM;
147
148	alert->alert_edge_triggered = setup->alert_edge_triggered;
149	alert->irq = setup->irq;
150	INIT_WORK(&alert->alert, smbus_alert);
151	alert->ara = ara;
152
153	if (setup->irq > 0) {
154	res = devm_request_irq(&ara->dev, setup->irq, smbalert_irq,
155	0, "smbus_alert", alert);
156	if (res) {
157	kfree(alert);
158	return res;
159	}
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
169	/* IRQ resource is managed so it is freed automatically */
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);
175
b5527a77 JD	176	kfree(alert);
	177	return 0;
	178	}
	179
	180	static const struct i2c_device_id smbalert_ids[] = {
	181	{ "smbus_alert", 0 },
	182	{ /* LIST END */ }
	183	};
	184	MODULE_DEVICE_TABLE(i2c, smbalert_ids);
	185
	186	static struct i2c_driver smbalert_driver = {
	187	.driver = {
	188	.name = "smbus_alert",
	189	},
	190	.probe = smbalert_probe,
	191	.remove = smbalert_remove,
	192	.id_table = smbalert_ids,
	193	};
	194
	195	/**
	196	* i2c_setup_smbus_alert - Setup SMBus alert support
	197	* @adapter: the target adapter
	198	* @setup: setup data for the SMBus alert handler
	199	* Context: can sleep
	200	*
	201	* Setup handling of the SMBus alert protocol on a given I2C bus segment.
	202	*
	203	* Handling can be done either through our IRQ handler, or by the
	204	* adapter (from its handler, periodic polling, or whatever).
	205	*
	206	* NOTE that if we manage the IRQ, we MUST know if it's level or
	207	* edge triggered in order to hand it to the workqueue correctly.
	208	* If triggering the alert seems to wedge the system, you probably
	209	* should have said it's level triggered.
	210	*
	211	* This returns the ara client, which should be saved for later use with
	212	* i2c_handle_smbus_alert() and ultimately i2c_unregister_device(); or NULL
	213	* to indicate an error.
	214	*/
	215	struct i2c_client i2c_setup_smbus_alert(struct i2c_adapter adapter,
	216	struct i2c_smbus_alert_setup *setup)
	217	{
	218	struct i2c_board_info ara_board_info = {
	219	I2C_BOARD_INFO("smbus_alert", 0x0c),
	220	.platform_data = setup,
	221	};
	222
	223	return i2c_new_device(adapter, &ara_board_info);
	224	}
	225	EXPORT_SYMBOL_GPL(i2c_setup_smbus_alert);
	226
	227	/**
	228	* i2c_handle_smbus_alert - Handle an SMBus alert
	229	* @ara: the ARA client on the relevant adapter
	230	* Context: can't sleep
	231	*
	232	* Helper function to be called from an I2C bus driver's interrupt
	233	* handler. It will schedule the alert work, in turn calling the
	234	* corresponding I2C device driver's alert function.
	235	*
	236	* It is assumed that ara is a valid i2c client previously returned by
	237	* i2c_setup_smbus_alert().
	238	*/
	239	int i2c_handle_smbus_alert(struct i2c_client *ara)
240	{
241	struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
242
243	return schedule_work(&alert->alert);
244	}
245	EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert);
246
247	static int __init i2c_smbus_init(void)
248	{
249	return i2c_add_driver(&smbalert_driver);
250	}
251
252	static void __exit i2c_smbus_exit(void)
253	{
254	i2c_del_driver(&smbalert_driver);
255	}
256
257	module_init(i2c_smbus_init);
258	module_exit(i2c_smbus_exit);
259
260	MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
261	MODULE_DESCRIPTION("SMBus protocol extensions support");
262	MODULE_LICENSE("GPL");