[mirror_ubuntu-jammy-kernel.git] / drivers / i2c / i2c-smbus.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * i2c-smbus.c - SMBus extensions to the I2C protocol
 *
 * Copyright (C) 2008 David Brownell
 * Copyright (C) 2010-2019 Jean Delvare <jdelvare@suse.de>
 */

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

struct i2c_smbus_alert {
	struct work_struct	alert;
	struct i2c_client	*ara;		/* Alert response address */
};

struct alert_data {
	unsigned short		addr;
	enum i2c_alert_protocol	type;
	unsigned int		data;
};

/* 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->type, data->data);
		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 irqreturn_t smbus_alert(int irq, void *d)
{
	struct i2c_smbus_alert *alert = d;
	struct i2c_client *ara;

	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.data = status & 1;
		data.addr = status >> 1;
		data.type = I2C_PROTOCOL_SMBUS_ALERT;

		dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n",
			data.addr, data.data);

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

	return IRQ_HANDLED;
}

static void smbalert_work(struct work_struct *work)
{
	struct i2c_smbus_alert *alert;

	alert = container_of(work, struct i2c_smbus_alert, alert);

	smbus_alert(0, alert);

}

/* 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, irq;

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

	if (setup) {
		irq = setup->irq;
	} else {
		irq = of_irq_get_byname(adapter->dev.of_node, "smbus_alert");
		if (irq <= 0)
			return irq;
	}

	INIT_WORK(&alert->alert, smbalert_work);
	alert->ara = ara;

	if (irq > 0) {
		res = devm_request_threaded_irq(&ara->dev, irq,
						NULL, smbus_alert,
						IRQF_SHARED | IRQF_ONESHOT,
						"smbus_alert", alert);
		if (res)
			return res;
	}

	i2c_set_clientdata(ara, alert);
	dev_info(&adapter->dev, "supports SMBALERT#\n");

	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_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_new_smbus_alert_device().
 */
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);

#if IS_ENABLED(CONFIG_I2C_SLAVE)
#define SMBUS_HOST_NOTIFY_LEN	3
struct i2c_slave_host_notify_status {
	u8 index;
	u8 addr;
};

static int i2c_slave_host_notify_cb(struct i2c_client *client,
				    enum i2c_slave_event event, u8 *val)
{
	struct i2c_slave_host_notify_status *status = client->dev.platform_data;

	switch (event) {
	case I2C_SLAVE_WRITE_RECEIVED:
		/* We only retrieve the first byte received (addr)
		 * since there is currently no support to retrieve the data
		 * parameter from the client.
		 */
		if (status->index == 0)
			status->addr = *val;
		if (status->index < U8_MAX)
			status->index++;
		break;
	case I2C_SLAVE_STOP:
		if (status->index == SMBUS_HOST_NOTIFY_LEN)
			i2c_handle_smbus_host_notify(client->adapter,
						     status->addr);
		fallthrough;
	case I2C_SLAVE_WRITE_REQUESTED:
		status->index = 0;
		break;
	case I2C_SLAVE_READ_REQUESTED:
	case I2C_SLAVE_READ_PROCESSED:
		*val = 0xff;
		break;
	}

	return 0;
}

/**
 * i2c_new_slave_host_notify_device - get a client for SMBus host-notify support
 * @adapter: the target adapter
 * Context: can sleep
 *
 * Setup handling of the SMBus host-notify protocol on a given I2C bus segment.
 *
 * Handling is done by creating a device and its callback and handling data
 * received via the SMBus host-notify address (0x8)
 *
 * This returns the client, which should be ultimately freed using
 * i2c_free_slave_host_notify_device(); or an ERRPTR to indicate an error.
 */
struct i2c_client *i2c_new_slave_host_notify_device(struct i2c_adapter *adapter)
{
	struct i2c_board_info host_notify_board_info = {
		I2C_BOARD_INFO("smbus_host_notify", 0x08),
		.flags  = I2C_CLIENT_SLAVE,
	};
	struct i2c_slave_host_notify_status *status;
	struct i2c_client *client;
	int ret;

	status = kzalloc(sizeof(struct i2c_slave_host_notify_status),
			 GFP_KERNEL);
	if (!status)
		return ERR_PTR(-ENOMEM);

	host_notify_board_info.platform_data = status;

	client = i2c_new_client_device(adapter, &host_notify_board_info);
	if (IS_ERR(client)) {
		kfree(status);
		return client;
	}

	ret = i2c_slave_register(client, i2c_slave_host_notify_cb);
	if (ret) {
		i2c_unregister_device(client);
		kfree(status);
		return ERR_PTR(ret);
	}

	return client;
}
EXPORT_SYMBOL_GPL(i2c_new_slave_host_notify_device);

/**
 * i2c_free_slave_host_notify_device - free the client for SMBus host-notify
 * support
 * @client: the client to free
 * Context: can sleep
 *
 * Free the i2c_client allocated via i2c_new_slave_host_notify_device
 */
void i2c_free_slave_host_notify_device(struct i2c_client *client)
{
	if (IS_ERR_OR_NULL(client))
		return;

	i2c_slave_unregister(client);
	kfree(client->dev.platform_data);
	i2c_unregister_device(client);
}
EXPORT_SYMBOL_GPL(i2c_free_slave_host_notify_device);
#endif

/*
 * SPD is not part of SMBus but we include it here for convenience as the
 * target systems are the same.
 * Restrictions to automatic SPD instantiation:
 *  - Only works if all filled slots have the same memory type
 *  - Only works for DDR2, DDR3 and DDR4 for now
 *  - Only works on systems with 1 to 4 memory slots
 */
#if IS_ENABLED(CONFIG_DMI)
void i2c_register_spd(struct i2c_adapter *adap)
{
	int n, slot_count = 0, dimm_count = 0;
	u16 handle;
	u8 common_mem_type = 0x0, mem_type;
	u64 mem_size;
	const char *name;

	while ((handle = dmi_memdev_handle(slot_count)) != 0xffff) {
		slot_count++;

		/* Skip empty slots */
		mem_size = dmi_memdev_size(handle);
		if (!mem_size)
			continue;

		/* Skip undefined memory type */
		mem_type = dmi_memdev_type(handle);
		if (mem_type <= 0x02)		/* Invalid, Other, Unknown */
			continue;

		if (!common_mem_type) {
			/* First filled slot */
			common_mem_type = mem_type;
		} else {
			/* Check that all filled slots have the same type */
			if (mem_type != common_mem_type) {
				dev_warn(&adap->dev,
					 "Different memory types mixed, not instantiating SPD\n");
				return;
			}
		}
		dimm_count++;
	}

	/* No useful DMI data, bail out */
	if (!dimm_count)
		return;

	dev_info(&adap->dev, "%d/%d memory slots populated (from DMI)\n",
		 dimm_count, slot_count);

	if (slot_count > 4) {
		dev_warn(&adap->dev,
			 "Systems with more than 4 memory slots not supported yet, not instantiating SPD\n");
		return;
	}

	switch (common_mem_type) {
	case 0x13:	/* DDR2 */
	case 0x18:	/* DDR3 */
	case 0x1C:	/* LPDDR2 */
	case 0x1D:	/* LPDDR3 */
		name = "spd";
		break;
	case 0x1A:	/* DDR4 */
	case 0x1E:	/* LPDDR4 */
		name = "ee1004";
		break;
	default:
		dev_info(&adap->dev,
			 "Memory type 0x%02x not supported yet, not instantiating SPD\n",
			 common_mem_type);
		return;
	}

	/*
	 * We don't know in which slots the memory modules are. We could
	 * try to guess from the slot names, but that would be rather complex
	 * and unreliable, so better probe all possible addresses until we
	 * have found all memory modules.
	 */
	for (n = 0; n < slot_count && dimm_count; n++) {
		struct i2c_board_info info;
		unsigned short addr_list[2];

		memset(&info, 0, sizeof(struct i2c_board_info));
		strlcpy(info.type, name, I2C_NAME_SIZE);
		addr_list[0] = 0x50 + n;
		addr_list[1] = I2C_CLIENT_END;

		if (!IS_ERR(i2c_new_scanned_device(adap, &info, addr_list, NULL))) {
			dev_info(&adap->dev,
				 "Successfully instantiated SPD at 0x%hx\n",
				 addr_list[0]);
			dimm_count--;
		}
	}
}
EXPORT_SYMBOL_GPL(i2c_register_spd);
#endif

MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
MODULE_DESCRIPTION("SMBus protocol extensions support");
MODULE_LICENSE("GPL");
Commit	Line	Data
c942fddf	1	// SPDX-License-Identifier: GPL-2.0-or-later
b5527a77 JD	2	/*
	3	* i2c-smbus.c - SMBus extensions to the I2C protocol
	4	*
	5	* Copyright (C) 2008 David Brownell
5ace6085	6	* Copyright (C) 2010-2019 Jean Delvare <jdelvare@suse.de>
b5527a77 JD	7	*/
b5527a77 JD	8
b5527a77	9	#include <linux/device.h>
5ace6085	10	#include <linux/dmi.h>
b5527a77 JD	11	#include <linux/i2c.h>
b5527a77 JD	12	#include <linux/i2c-smbus.h>
62c874ab WS	13	#include <linux/interrupt.h>
	14	#include <linux/kernel.h>
	15	#include <linux/module.h>
69d17246	16	#include <linux/of_irq.h>
5a0e3ad6	17	#include <linux/slab.h>
62c874ab	18	#include <linux/workqueue.h>
b5527a77 JD	19
b5527a77 JD	20	struct i2c_smbus_alert {
b5527a77 JD	21	struct work_struct alert;
	22	struct i2c_client ara; / Alert response address */
	23	};
	24
	25	struct alert_data {
	26	unsigned short addr;
e456cd37 BT	27	enum i2c_alert_protocol type;
e456cd37 BT	28	unsigned int data;
b5527a77 JD	29	};
	30
	31	/* If this is the alerting device, notify its driver */
	32	static int smbus_do_alert(struct device dev, void addrp)
	33	{
	34	struct i2c_client *client = i2c_verify_client(dev);
	35	struct alert_data *data = addrp;
0acc2b32	36	struct i2c_driver *driver;
b5527a77 JD	37
	38	if (!client \|\| client->addr != data->addr)
	39	return 0;
	40	if (client->flags & I2C_CLIENT_TEN)
	41	return 0;
	42
	43	/*
	44	* Drivers should either disable alerts, or provide at least
0acc2b32	45	* a minimal handler. Lock so the driver won't change.
b5527a77	46	*/
f635a1e7	47	device_lock(dev);
0acc2b32 LPC	48	if (client->dev.driver) {
	49	driver = to_i2c_driver(client->dev.driver);
	50	if (driver->alert)
e456cd37	51	driver->alert(client, data->type, data->data);
b5527a77 JD	52	else
	53	dev_warn(&client->dev, "no driver alert()!\n");
	54	} else
	55	dev_dbg(&client->dev, "alert with no driver\n");
f635a1e7	56	device_unlock(dev);
b5527a77 JD	57
	58	/* Stop iterating after we find the device */
	59	return -EBUSY;
	60	}
	61
	62	/*
	63	* The alert IRQ handler needs to hand work off to a task which can issue
	64	* SMBus calls, because those sleeping calls can't be made in IRQ context.
	65	*/
9b9f2b8b	66	static irqreturn_t smbus_alert(int irq, void *d)
b5527a77	67	{
9b9f2b8b	68	struct i2c_smbus_alert *alert = d;
b5527a77	69	struct i2c_client *ara;
b5527a77	70
b5527a77 JD	71	ara = alert->ara;
	72
	73	for (;;) {
	74	s32 status;
	75	struct alert_data data;
	76
	77	/*
	78	* Devices with pending alerts reply in address order, low
	79	* to high, because of slave transmit arbitration. After
	80	* responding, an SMBus device stops asserting SMBALERT#.
	81	*
edc9102a	82	* Note that SMBus 2.0 reserves 10-bit addresses for future
b5527a77 JD	83	* use. We neither handle them, nor try to use PEC here.
	84	*/
	85	status = i2c_smbus_read_byte(ara);
	86	if (status < 0)
	87	break;
	88
e456cd37	89	data.data = status & 1;
b5527a77	90	data.addr = status >> 1;
e456cd37	91	data.type = I2C_PROTOCOL_SMBUS_ALERT;
b5527a77	92
b5527a77	93	dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n",
e456cd37	94	data.addr, data.data);
b5527a77 JD	95
	96	/* Notify driver for the device which issued the alert */
	97	device_for_each_child(&ara->adapter->dev, &data,
	98	smbus_do_alert);
b5527a77 JD	99	}
b5527a77 JD	100
9b9f2b8b	101	return IRQ_HANDLED;
b5527a77 JD	102	}
b5527a77 JD	103
9b9f2b8b	104	static void smbalert_work(struct work_struct *work)
b5527a77	105	{
9b9f2b8b PR	106	struct i2c_smbus_alert *alert;
	107
	108	alert = container_of(work, struct i2c_smbus_alert, alert);
b5527a77	109
9b9f2b8b	110	smbus_alert(0, alert);
b5527a77	111
b5527a77 JD	112	}
	113
	114	/* Setup SMBALERT# infrastructure */
	115	static int smbalert_probe(struct i2c_client *ara,
	116	const struct i2c_device_id *id)
	117	{
6d4028c6	118	struct i2c_smbus_alert_setup *setup = dev_get_platdata(&ara->dev);
b5527a77 JD	119	struct i2c_smbus_alert *alert;
b5527a77 JD	120	struct i2c_adapter *adapter = ara->adapter;
9b9f2b8b	121	int res, irq;
b5527a77	122
71b57845 JL	123	alert = devm_kzalloc(&ara->dev, sizeof(struct i2c_smbus_alert),
71b57845 JL	124	GFP_KERNEL);
b5527a77 JD	125	if (!alert)
	126	return -ENOMEM;
	127
69d17246 PR	128	if (setup) {
	129	irq = setup->irq;
	130	} else {
	131	irq = of_irq_get_byname(adapter->dev.of_node, "smbus_alert");
	132	if (irq <= 0)
	133	return irq;
	134	}
	135
9b9f2b8b	136	INIT_WORK(&alert->alert, smbalert_work);
b5527a77 JD	137	alert->ara = ara;
b5527a77 JD	138
9b9f2b8b PR	139	if (irq > 0) {
	140	res = devm_request_threaded_irq(&ara->dev, irq,
	141	NULL, smbus_alert,
	142	IRQF_SHARED \| IRQF_ONESHOT,
	143	"smbus_alert", alert);
71b57845	144	if (res)
b5527a77	145	return res;
b5527a77 JD	146	}
	147
	148	i2c_set_clientdata(ara, alert);
9b9f2b8b	149	dev_info(&adapter->dev, "supports SMBALERT#\n");
b5527a77 JD	150
	151	return 0;
	152	}
	153
71b57845	154	/* IRQ and memory resources are managed so they are freed automatically */
b5527a77 JD	155	static int smbalert_remove(struct i2c_client *ara)
	156	{
	157	struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
	158
	159	cancel_work_sync(&alert->alert);
b5527a77 JD	160	return 0;
	161	}
	162
	163	static const struct i2c_device_id smbalert_ids[] = {
	164	{ "smbus_alert", 0 },
	165	{ /* LIST END */ }
	166	};
	167	MODULE_DEVICE_TABLE(i2c, smbalert_ids);
	168
	169	static struct i2c_driver smbalert_driver = {
	170	.driver = {
	171	.name = "smbus_alert",
	172	},
	173	.probe = smbalert_probe,
	174	.remove = smbalert_remove,
	175	.id_table = smbalert_ids,
	176	};
	177
b5527a77 JD	178	/**
	179	* i2c_handle_smbus_alert - Handle an SMBus alert
	180	* @ara: the ARA client on the relevant adapter
	181	* Context: can't sleep
	182	*
	183	* Helper function to be called from an I2C bus driver's interrupt
	184	* handler. It will schedule the alert work, in turn calling the
	185	* corresponding I2C device driver's alert function.
	186	*
	187	* It is assumed that ara is a valid i2c client previously returned by
ed680522	188	* i2c_new_smbus_alert_device().
b5527a77 JD	189	*/
	190	int i2c_handle_smbus_alert(struct i2c_client *ara)
	191	{
	192	struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
	193
	194	return schedule_work(&alert->alert);
	195	}
	196	EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert);
	197
fda2f4af	198	module_i2c_driver(smbalert_driver);
b5527a77	199
2a71593d AV	200	#if IS_ENABLED(CONFIG_I2C_SLAVE)
	201	#define SMBUS_HOST_NOTIFY_LEN 3
	202	struct i2c_slave_host_notify_status {
	203	u8 index;
	204	u8 addr;
	205	};
	206
	207	static int i2c_slave_host_notify_cb(struct i2c_client *client,
	208	enum i2c_slave_event event, u8 *val)
	209	{
	210	struct i2c_slave_host_notify_status *status = client->dev.platform_data;
	211
	212	switch (event) {
	213	case I2C_SLAVE_WRITE_RECEIVED:
	214	/* We only retrieve the first byte received (addr)
	215	* since there is currently no support to retrieve the data
	216	* parameter from the client.
	217	*/
	218	if (status->index == 0)
	219	status->addr = *val;
	220	if (status->index < U8_MAX)
	221	status->index++;
	222	break;
	223	case I2C_SLAVE_STOP:
	224	if (status->index == SMBUS_HOST_NOTIFY_LEN)
	225	i2c_handle_smbus_host_notify(client->adapter,
	226	status->addr);
	227	fallthrough;
	228	case I2C_SLAVE_WRITE_REQUESTED:
	229	status->index = 0;
	230	break;
	231	case I2C_SLAVE_READ_REQUESTED:
	232	case I2C_SLAVE_READ_PROCESSED:
	233	*val = 0xff;
	234	break;
	235	}
	236
	237	return 0;
	238	}
	239
	240	/**
	241	* i2c_new_slave_host_notify_device - get a client for SMBus host-notify support
	242	* @adapter: the target adapter
	243	* Context: can sleep
	244	*
	245	* Setup handling of the SMBus host-notify protocol on a given I2C bus segment.
	246	*
	247	* Handling is done by creating a device and its callback and handling data
	248	* received via the SMBus host-notify address (0x8)
	249	*
	250	* This returns the client, which should be ultimately freed using
	251	* i2c_free_slave_host_notify_device(); or an ERRPTR to indicate an error.
	252	*/
	253	struct i2c_client i2c_new_slave_host_notify_device(struct i2c_adapter adapter)
	254	{
	255	struct i2c_board_info host_notify_board_info = {
	256	I2C_BOARD_INFO("smbus_host_notify", 0x08),
	257	.flags = I2C_CLIENT_SLAVE,
	258	};
	259	struct i2c_slave_host_notify_status *status;
	260	struct i2c_client *client;
	261	int ret;
	262
	263	status = kzalloc(sizeof(struct i2c_slave_host_notify_status),
264	GFP_KERNEL);
265	if (!status)
266	return ERR_PTR(-ENOMEM);
267
268	host_notify_board_info.platform_data = status;
269
270	client = i2c_new_client_device(adapter, &host_notify_board_info);
271	if (IS_ERR(client)) {
272	kfree(status);
273	return client;
274	}
275
276	ret = i2c_slave_register(client, i2c_slave_host_notify_cb);
277	if (ret) {
278	i2c_unregister_device(client);
279	kfree(status);
280	return ERR_PTR(ret);
281	}
282
283	return client;
284	}
285	EXPORT_SYMBOL_GPL(i2c_new_slave_host_notify_device);
286
287	/**
288	* i2c_free_slave_host_notify_device - free the client for SMBus host-notify
289	* support
290	* @client: the client to free
291	* Context: can sleep
292	*
293	* Free the i2c_client allocated via i2c_new_slave_host_notify_device
294	*/
295	void i2c_free_slave_host_notify_device(struct i2c_client *client)
296	{
297	if (IS_ERR_OR_NULL(client))
298	return;
299
300	i2c_slave_unregister(client);
301	kfree(client->dev.platform_data);
302	i2c_unregister_device(client);
303	}
304	EXPORT_SYMBOL_GPL(i2c_free_slave_host_notify_device);
305	#endif
306
5ace6085 JD	307	/*
	308	* SPD is not part of SMBus but we include it here for convenience as the
	309	* target systems are the same.
	310	* Restrictions to automatic SPD instantiation:
	311	* - Only works if all filled slots have the same memory type
	312	* - Only works for DDR2, DDR3 and DDR4 for now
	313	* - Only works on systems with 1 to 4 memory slots
	314	*/
	315	#if IS_ENABLED(CONFIG_DMI)
	316	void i2c_register_spd(struct i2c_adapter *adap)
	317	{
	318	int n, slot_count = 0, dimm_count = 0;
	319	u16 handle;
	320	u8 common_mem_type = 0x0, mem_type;
	321	u64 mem_size;
	322	const char *name;
	323
	324	while ((handle = dmi_memdev_handle(slot_count)) != 0xffff) {
	325	slot_count++;
	326
	327	/* Skip empty slots */
	328	mem_size = dmi_memdev_size(handle);
	329	if (!mem_size)
	330	continue;
	331
	332	/* Skip undefined memory type */
	333	mem_type = dmi_memdev_type(handle);
	334	if (mem_type <= 0x02) /* Invalid, Other, Unknown */
	335	continue;
	336
	337	if (!common_mem_type) {
	338	/* First filled slot */
	339	common_mem_type = mem_type;
	340	} else {
	341	/* Check that all filled slots have the same type */
	342	if (mem_type != common_mem_type) {
	343	dev_warn(&adap->dev,
	344	"Different memory types mixed, not instantiating SPD\n");
	345	return;
	346	}
	347	}
	348	dimm_count++;
	349	}
	350
	351	/* No useful DMI data, bail out */
	352	if (!dimm_count)
	353	return;
	354
	355	dev_info(&adap->dev, "%d/%d memory slots populated (from DMI)\n",
	356	dimm_count, slot_count);
	357
	358	if (slot_count > 4) {
	359	dev_warn(&adap->dev,
	360	"Systems with more than 4 memory slots not supported yet, not instantiating SPD\n");
	361	return;
	362	}
	363
	364	switch (common_mem_type) {
	365	case 0x13: /* DDR2 */
	366	case 0x18: /* DDR3 */
	367	case 0x1C: /* LPDDR2 */
	368	case 0x1D: /* LPDDR3 */
	369	name = "spd";
	370	break;
371	case 0x1A: /* DDR4 */
372	case 0x1E: /* LPDDR4 */
373	name = "ee1004";
374	break;
375	default:
376	dev_info(&adap->dev,
377	"Memory type 0x%02x not supported yet, not instantiating SPD\n",
378	common_mem_type);
379	return;
380	}
381
382	/*
383	* We don't know in which slots the memory modules are. We could
384	* try to guess from the slot names, but that would be rather complex
385	* and unreliable, so better probe all possible addresses until we
386	* have found all memory modules.
387	*/
388	for (n = 0; n < slot_count && dimm_count; n++) {
389	struct i2c_board_info info;
390	unsigned short addr_list[2];
391
392	memset(&info, 0, sizeof(struct i2c_board_info));
393	strlcpy(info.type, name, I2C_NAME_SIZE);
394	addr_list[0] = 0x50 + n;
395	addr_list[1] = I2C_CLIENT_END;
396
397	if (!IS_ERR(i2c_new_scanned_device(adap, &info, addr_list, NULL))) {
398	dev_info(&adap->dev,
399	"Successfully instantiated SPD at 0x%hx\n",
400	addr_list[0]);
401	dimm_count--;
402	}
403	}
404	}
405	EXPORT_SYMBOL_GPL(i2c_register_spd);
406	#endif
407
7c81c60f	408	MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
b5527a77 JD	409	MODULE_DESCRIPTION("SMBus protocol extensions support");
b5527a77 JD	410	MODULE_LICENSE("GPL");