[linux.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 <[email protected]>
 *
 * 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.
 */

#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;
	struct i2c_driver *driver;

	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 the driver won't change.
	 */
	device_lock(dev);
	if (client->dev.driver) {
		driver = to_i2c_driver(client->dev.driver);
		if (driver->alert)
			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 addresses 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 = dev_get_platdata(&ara->dev);
	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 <[email protected]>");
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
7c81c60f	5	* Copyright (C) 2010 Jean Delvare <[email protected]>
b5527a77 JD	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.
b5527a77 JD	16	*/
	17
	18	#include <linux/kernel.h>
	19	#include <linux/module.h>
	20	#include <linux/device.h>
b5527a77 JD	21	#include <linux/interrupt.h>
	22	#include <linux/workqueue.h>
	23	#include <linux/i2c.h>
	24	#include <linux/i2c-smbus.h>
5a0e3ad6	25	#include <linux/slab.h>
b5527a77 JD	26
	27	struct i2c_smbus_alert {
	28	unsigned int alert_edge_triggered:1;
	29	int irq;
	30	struct work_struct alert;
	31	struct i2c_client ara; / Alert response address */
	32	};
	33
	34	struct alert_data {
	35	unsigned short addr;
	36	u8 flag:1;
	37	};
	38
	39	/* If this is the alerting device, notify its driver */
	40	static int smbus_do_alert(struct device dev, void addrp)
	41	{
	42	struct i2c_client *client = i2c_verify_client(dev);
	43	struct alert_data *data = addrp;
0acc2b32	44	struct i2c_driver *driver;
b5527a77 JD	45
	46	if (!client \|\| client->addr != data->addr)
	47	return 0;
	48	if (client->flags & I2C_CLIENT_TEN)
	49	return 0;
	50
	51	/*
	52	* Drivers should either disable alerts, or provide at least
0acc2b32	53	* a minimal handler. Lock so the driver won't change.
b5527a77	54	*/
f635a1e7	55	device_lock(dev);
0acc2b32 LPC	56	if (client->dev.driver) {
	57	driver = to_i2c_driver(client->dev.driver);
	58	if (driver->alert)
	59	driver->alert(client, data->flag);
b5527a77 JD	60	else
	61	dev_warn(&client->dev, "no driver alert()!\n");
	62	} else
	63	dev_dbg(&client->dev, "alert with no driver\n");
f635a1e7	64	device_unlock(dev);
b5527a77 JD	65
	66	/* Stop iterating after we find the device */
	67	return -EBUSY;
	68	}
	69
	70	/*
	71	* The alert IRQ handler needs to hand work off to a task which can issue
	72	* SMBus calls, because those sleeping calls can't be made in IRQ context.
	73	*/
	74	static void smbus_alert(struct work_struct *work)
	75	{
	76	struct i2c_smbus_alert *alert;
	77	struct i2c_client *ara;
	78	unsigned short prev_addr = 0; /* Not a valid address */
	79
	80	alert = container_of(work, struct i2c_smbus_alert, alert);
	81	ara = alert->ara;
	82
	83	for (;;) {
	84	s32 status;
	85	struct alert_data data;
	86
	87	/*
	88	* Devices with pending alerts reply in address order, low
	89	* to high, because of slave transmit arbitration. After
	90	* responding, an SMBus device stops asserting SMBALERT#.
	91	*
edc9102a	92	* Note that SMBus 2.0 reserves 10-bit addresses for future
b5527a77 JD	93	* use. We neither handle them, nor try to use PEC here.
	94	*/
	95	status = i2c_smbus_read_byte(ara);
	96	if (status < 0)
	97	break;
	98
	99	data.flag = status & 1;
	100	data.addr = status >> 1;
	101
	102	if (data.addr == prev_addr) {
	103	dev_warn(&ara->dev, "Duplicate SMBALERT# from dev "
	104	"0x%02x, skipping\n", data.addr);
	105	break;
	106	}
	107	dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n",
	108	data.addr, data.flag);
	109
	110	/* Notify driver for the device which issued the alert */
	111	device_for_each_child(&ara->adapter->dev, &data,
	112	smbus_do_alert);
	113	prev_addr = data.addr;
	114	}
	115
	116	/* We handled all alerts; re-enable level-triggered IRQs */
	117	if (!alert->alert_edge_triggered)
	118	enable_irq(alert->irq);
	119	}
	120
	121	static irqreturn_t smbalert_irq(int irq, void *d)
	122	{
	123	struct i2c_smbus_alert *alert = d;
	124
	125	/* Disable level-triggered IRQs until we handle them */
	126	if (!alert->alert_edge_triggered)
	127	disable_irq_nosync(irq);
	128
	129	schedule_work(&alert->alert);
	130	return IRQ_HANDLED;
	131	}
	132
	133	/* Setup SMBALERT# infrastructure */
	134	static int smbalert_probe(struct i2c_client *ara,
	135	const struct i2c_device_id *id)
	136	{
6d4028c6	137	struct i2c_smbus_alert_setup *setup = dev_get_platdata(&ara->dev);
b5527a77 JD	138	struct i2c_smbus_alert *alert;
	139	struct i2c_adapter *adapter = ara->adapter;
	140	int res;
	141
71b57845 JL	142	alert = devm_kzalloc(&ara->dev, sizeof(struct i2c_smbus_alert),
71b57845 JL	143	GFP_KERNEL);
b5527a77 JD	144	if (!alert)
	145	return -ENOMEM;
	146
	147	alert->alert_edge_triggered = setup->alert_edge_triggered;
	148	alert->irq = setup->irq;
	149	INIT_WORK(&alert->alert, smbus_alert);
	150	alert->ara = ara;
	151
	152	if (setup->irq > 0) {
	153	res = devm_request_irq(&ara->dev, setup->irq, smbalert_irq,
	154	0, "smbus_alert", alert);
71b57845	155	if (res)
b5527a77	156	return res;
b5527a77 JD	157	}
	158
	159	i2c_set_clientdata(ara, alert);
	160	dev_info(&adapter->dev, "supports SMBALERT#, %s trigger\n",
	161	setup->alert_edge_triggered ? "edge" : "level");
	162
	163	return 0;
	164	}
	165
71b57845	166	/* IRQ and memory resources are managed so they are freed automatically */
b5527a77 JD	167	static int smbalert_remove(struct i2c_client *ara)
	168	{
	169	struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
	170
	171	cancel_work_sync(&alert->alert);
b5527a77 JD	172	return 0;
	173	}
	174
	175	static const struct i2c_device_id smbalert_ids[] = {
	176	{ "smbus_alert", 0 },
	177	{ /* LIST END */ }
	178	};
	179	MODULE_DEVICE_TABLE(i2c, smbalert_ids);
	180
	181	static struct i2c_driver smbalert_driver = {
	182	.driver = {
	183	.name = "smbus_alert",
	184	},
	185	.probe = smbalert_probe,
	186	.remove = smbalert_remove,
	187	.id_table = smbalert_ids,
	188	};
	189
	190	/**
	191	* i2c_setup_smbus_alert - Setup SMBus alert support
	192	* @adapter: the target adapter
	193	* @setup: setup data for the SMBus alert handler
	194	* Context: can sleep
	195	*
	196	* Setup handling of the SMBus alert protocol on a given I2C bus segment.
	197	*
	198	* Handling can be done either through our IRQ handler, or by the
	199	* adapter (from its handler, periodic polling, or whatever).
	200	*
	201	* NOTE that if we manage the IRQ, we MUST know if it's level or
	202	* edge triggered in order to hand it to the workqueue correctly.
	203	* If triggering the alert seems to wedge the system, you probably
	204	* should have said it's level triggered.
	205	*
	206	* This returns the ara client, which should be saved for later use with
	207	* i2c_handle_smbus_alert() and ultimately i2c_unregister_device(); or NULL
	208	* to indicate an error.
	209	*/
	210	struct i2c_client i2c_setup_smbus_alert(struct i2c_adapter adapter,
	211	struct i2c_smbus_alert_setup *setup)
	212	{
	213	struct i2c_board_info ara_board_info = {
	214	I2C_BOARD_INFO("smbus_alert", 0x0c),
	215	.platform_data = setup,
	216	};
	217
	218	return i2c_new_device(adapter, &ara_board_info);
	219	}
	220	EXPORT_SYMBOL_GPL(i2c_setup_smbus_alert);
	221
	222	/**
	223	* i2c_handle_smbus_alert - Handle an SMBus alert
	224	* @ara: the ARA client on the relevant adapter
	225	* Context: can't sleep
	226	*
	227	* Helper function to be called from an I2C bus driver's interrupt
	228	* handler. It will schedule the alert work, in turn calling the
	229	* corresponding I2C device driver's alert function.
	230	*
	231	* It is assumed that ara is a valid i2c client previously returned by
	232	* i2c_setup_smbus_alert().
	233	*/
	234	int i2c_handle_smbus_alert(struct i2c_client *ara)
	235	{
236	struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
237
238	return schedule_work(&alert->alert);
239	}
240	EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert);
241
fda2f4af	242	module_i2c_driver(smbalert_driver);
b5527a77	243
7c81c60f	244	MODULE_AUTHOR("Jean Delvare <[email protected]>");
b5527a77 JD	245	MODULE_DESCRIPTION("SMBus protocol extensions support");
b5527a77 JD	246	MODULE_LICENSE("GPL");