[linux-block.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/property.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;
	int ret;

	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) {
			/* Stop iterating after we find the device */
			driver->alert(client, data->type, data->data);
			ret = -EBUSY;
		} else {
			dev_warn(&client->dev, "no driver alert()!\n");
			ret = -EOPNOTSUPP;
		}
	} else {
		dev_dbg(&client->dev, "alert with no driver\n");
		ret = -ENODEV;
	}
	device_unlock(dev);

	return ret;
}

/* Same as above, but call back all drivers with alert handler */

static int smbus_do_alert_force(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->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);
	}
	device_unlock(dev);

	return 0;
}

/*
 * 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;
	unsigned short prev_addr = I2C_CLIENT_END; /* Not a valid address */

	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 */
		status = device_for_each_child(&ara->adapter->dev, &data,
					       smbus_do_alert);
		/*
		 * If we read the same address more than once, and the alert
		 * was not handled by a driver, it won't do any good to repeat
		 * the loop because it will never terminate. Try again, this
		 * time calling the alert handlers of all devices connected to
		 * the bus, and abort the loop afterwards. If this helps, we
		 * are all set. If it doesn't, there is nothing else we can do,
		 * so we might as well abort the loop.
		 * Note: This assumes that a driver with alert handler handles
		 * the alert properly and clears it if necessary.
		 */
		if (data.addr == prev_addr && status != -EBUSY) {
			device_for_each_child(&ara->adapter->dev, &data,
					      smbus_do_alert_force);
			break;
		}
		prev_addr = data.addr;
	}

	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)
{
	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 = fwnode_irq_get_byname(dev_fwnode(adapter->dev.parent),
					    "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 void smbalert_remove(struct i2c_client *ara)
{
	struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);

	cancel_work_sync(&alert->alert);
}

static const struct i2c_device_id smbalert_ids[] = {
	{ "smbus_alert" },
	{ /* 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 (LP)DDR memory types up to DDR5
 *  - Only works on systems with 1 to 8 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;

	/*
	 * The max number of SPD EEPROMs that can be addressed per bus is 8.
	 * If more slots are present either muxed or multiple busses are
	 * necessary or the additional slots are ignored.
	 */
	slot_count = min(slot_count, 8);

	/*
	 * Memory types could be found at section 7.18.2 (Memory Device — Type), table 78
	 * https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.6.0.pdf
	 */
	switch (common_mem_type) {
	case 0x12:	/* DDR */
	case 0x13:	/* DDR2 */
	case 0x18:	/* DDR3 */
	case 0x1B:	/* LPDDR */
	case 0x1C:	/* LPDDR2 */
	case 0x1D:	/* LPDDR3 */
		name = "spd";
		break;
	case 0x1A:	/* DDR4 */
	case 0x1E:	/* LPDDR4 */
		name = "ee1004";
		break;
	case 0x22:	/* DDR5 */
	case 0x23:	/* LPDDR5 */
		name = "spd5118";
		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));
		strscpy(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>
a263a840	16	#include <linux/property.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;
37c526f0	37	int ret;
b5527a77 JD	38
	39	if (!client \|\| client->addr != data->addr)
	40	return 0;
	41	if (client->flags & I2C_CLIENT_TEN)
	42	return 0;
	43
	44	/*
	45	* Drivers should either disable alerts, or provide at least
0acc2b32	46	* a minimal handler. Lock so the driver won't change.
b5527a77	47	*/
f635a1e7	48	device_lock(dev);
0acc2b32 LPC	49	if (client->dev.driver) {
0acc2b32 LPC	50	driver = to_i2c_driver(client->dev.driver);
37c526f0 GR	51	if (driver->alert) {
37c526f0 GR	52	/* Stop iterating after we find the device */
e456cd37	53	driver->alert(client, data->type, data->data);
37c526f0 GR	54	ret = -EBUSY;
37c526f0 GR	55	} else {
b5527a77	56	dev_warn(&client->dev, "no driver alert()!\n");
37c526f0 GR	57	ret = -EOPNOTSUPP;
	58	}
	59	} else {
b5527a77	60	dev_dbg(&client->dev, "alert with no driver\n");
37c526f0 GR	61	ret = -ENODEV;
37c526f0 GR	62	}
f635a1e7	63	device_unlock(dev);
b5527a77	64
37c526f0	65	return ret;
b5527a77 JD	66	}
b5527a77 JD	67
f6c29f71 GR	68	/* Same as above, but call back all drivers with alert handler */
	69
	70	static int smbus_do_alert_force(struct device dev, void addrp)
	71	{
	72	struct i2c_client *client = i2c_verify_client(dev);
	73	struct alert_data *data = addrp;
	74	struct i2c_driver *driver;
	75
	76	if (!client \|\| (client->flags & I2C_CLIENT_TEN))
	77	return 0;
	78
	79	/*
	80	* Drivers should either disable alerts, or provide at least
	81	* a minimal handler. Lock so the driver won't change.
	82	*/
	83	device_lock(dev);
	84	if (client->dev.driver) {
	85	driver = to_i2c_driver(client->dev.driver);
	86	if (driver->alert)
	87	driver->alert(client, data->type, data->data);
	88	}
	89	device_unlock(dev);
	90
	91	return 0;
	92	}
	93
b5527a77 JD	94	/*
	95	* The alert IRQ handler needs to hand work off to a task which can issue
	96	* SMBus calls, because those sleeping calls can't be made in IRQ context.
	97	*/
9b9f2b8b	98	static irqreturn_t smbus_alert(int irq, void *d)
b5527a77	99	{
9b9f2b8b	100	struct i2c_smbus_alert *alert = d;
b5527a77	101	struct i2c_client *ara;
37c526f0	102	unsigned short prev_addr = I2C_CLIENT_END; /* Not a valid address */
b5527a77	103
b5527a77 JD	104	ara = alert->ara;
	105
	106	for (;;) {
	107	s32 status;
	108	struct alert_data data;
	109
	110	/*
	111	* Devices with pending alerts reply in address order, low
	112	* to high, because of slave transmit arbitration. After
	113	* responding, an SMBus device stops asserting SMBALERT#.
	114	*
edc9102a	115	* Note that SMBus 2.0 reserves 10-bit addresses for future
b5527a77 JD	116	* use. We neither handle them, nor try to use PEC here.
	117	*/
	118	status = i2c_smbus_read_byte(ara);
	119	if (status < 0)
	120	break;
	121
e456cd37	122	data.data = status & 1;
b5527a77	123	data.addr = status >> 1;
e456cd37	124	data.type = I2C_PROTOCOL_SMBUS_ALERT;
b5527a77	125
b5527a77	126	dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n",
e456cd37	127	data.addr, data.data);
b5527a77 JD	128
b5527a77 JD	129	/* Notify driver for the device which issued the alert */
37c526f0 GR	130	status = device_for_each_child(&ara->adapter->dev, &data,
	131	smbus_do_alert);
	132	/*
	133	* If we read the same address more than once, and the alert
	134	* was not handled by a driver, it won't do any good to repeat
f6c29f71 GR	135	* the loop because it will never terminate. Try again, this
	136	* time calling the alert handlers of all devices connected to
	137	* the bus, and abort the loop afterwards. If this helps, we
	138	* are all set. If it doesn't, there is nothing else we can do,
	139	* so we might as well abort the loop.
37c526f0 GR	140	* Note: This assumes that a driver with alert handler handles
	141	* the alert properly and clears it if necessary.
	142	*/
f6c29f71 GR	143	if (data.addr == prev_addr && status != -EBUSY) {
	144	device_for_each_child(&ara->adapter->dev, &data,
	145	smbus_do_alert_force);
37c526f0	146	break;
f6c29f71	147	}
37c526f0	148	prev_addr = data.addr;
b5527a77 JD	149	}
b5527a77 JD	150
9b9f2b8b	151	return IRQ_HANDLED;
b5527a77 JD	152	}
b5527a77 JD	153
9b9f2b8b	154	static void smbalert_work(struct work_struct *work)
b5527a77	155	{
9b9f2b8b PR	156	struct i2c_smbus_alert *alert;
	157
	158	alert = container_of(work, struct i2c_smbus_alert, alert);
b5527a77	159
9b9f2b8b	160	smbus_alert(0, alert);
b5527a77	161
b5527a77 JD	162	}
	163
	164	/* Setup SMBALERT# infrastructure */
a00f6d37	165	static int smbalert_probe(struct i2c_client *ara)
b5527a77	166	{
6d4028c6	167	struct i2c_smbus_alert_setup *setup = dev_get_platdata(&ara->dev);
b5527a77 JD	168	struct i2c_smbus_alert *alert;
b5527a77 JD	169	struct i2c_adapter *adapter = ara->adapter;
9b9f2b8b	170	int res, irq;
b5527a77	171
71b57845 JL	172	alert = devm_kzalloc(&ara->dev, sizeof(struct i2c_smbus_alert),
71b57845 JL	173	GFP_KERNEL);
b5527a77 JD	174	if (!alert)
	175	return -ENOMEM;
	176
69d17246 PR	177	if (setup) {
	178	irq = setup->irq;
	179	} else {
a263a840 A	180	irq = fwnode_irq_get_byname(dev_fwnode(adapter->dev.parent),
a263a840 A	181	"smbus_alert");
69d17246 PR	182	if (irq <= 0)
	183	return irq;
	184	}
	185
9b9f2b8b	186	INIT_WORK(&alert->alert, smbalert_work);
b5527a77 JD	187	alert->ara = ara;
b5527a77 JD	188
9b9f2b8b PR	189	if (irq > 0) {
	190	res = devm_request_threaded_irq(&ara->dev, irq,
	191	NULL, smbus_alert,
	192	IRQF_SHARED \| IRQF_ONESHOT,
	193	"smbus_alert", alert);
71b57845	194	if (res)
b5527a77	195	return res;
b5527a77 JD	196	}
	197
	198	i2c_set_clientdata(ara, alert);
9b9f2b8b	199	dev_info(&adapter->dev, "supports SMBALERT#\n");
b5527a77 JD	200
	201	return 0;
	202	}
	203
71b57845	204	/* IRQ and memory resources are managed so they are freed automatically */
ed5c2f5f	205	static void smbalert_remove(struct i2c_client *ara)
b5527a77 JD	206	{
	207	struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
	208
	209	cancel_work_sync(&alert->alert);
b5527a77 JD	210	}
	211
	212	static const struct i2c_device_id smbalert_ids[] = {
d08ed106	213	{ "smbus_alert" },
b5527a77 JD	214	{ /* LIST END */ }
	215	};
	216	MODULE_DEVICE_TABLE(i2c, smbalert_ids);
	217
	218	static struct i2c_driver smbalert_driver = {
	219	.driver = {
	220	.name = "smbus_alert",
	221	},
834a9dc4	222	.probe = smbalert_probe,
b5527a77 JD	223	.remove = smbalert_remove,
	224	.id_table = smbalert_ids,
	225	};
	226
b5527a77 JD	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
ed680522	237	* i2c_new_smbus_alert_device().
b5527a77 JD	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
fda2f4af	247	module_i2c_driver(smbalert_driver);
b5527a77	248
2a71593d AV	249	#if IS_ENABLED(CONFIG_I2C_SLAVE)
	250	#define SMBUS_HOST_NOTIFY_LEN 3
	251	struct i2c_slave_host_notify_status {
	252	u8 index;
	253	u8 addr;
	254	};
	255
	256	static int i2c_slave_host_notify_cb(struct i2c_client *client,
	257	enum i2c_slave_event event, u8 *val)
	258	{
	259	struct i2c_slave_host_notify_status *status = client->dev.platform_data;
	260
	261	switch (event) {
	262	case I2C_SLAVE_WRITE_RECEIVED:
	263	/* We only retrieve the first byte received (addr)
	264	* since there is currently no support to retrieve the data
	265	* parameter from the client.
	266	*/
	267	if (status->index == 0)
	268	status->addr = *val;
	269	if (status->index < U8_MAX)
	270	status->index++;
	271	break;
	272	case I2C_SLAVE_STOP:
	273	if (status->index == SMBUS_HOST_NOTIFY_LEN)
	274	i2c_handle_smbus_host_notify(client->adapter,
	275	status->addr);
	276	fallthrough;
	277	case I2C_SLAVE_WRITE_REQUESTED:
	278	status->index = 0;
	279	break;
	280	case I2C_SLAVE_READ_REQUESTED:
	281	case I2C_SLAVE_READ_PROCESSED:
	282	*val = 0xff;
	283	break;
	284	}
	285
	286	return 0;
	287	}
	288
	289	/**
	290	* i2c_new_slave_host_notify_device - get a client for SMBus host-notify support
	291	* @adapter: the target adapter
	292	* Context: can sleep
	293	*
	294	* Setup handling of the SMBus host-notify protocol on a given I2C bus segment.
	295	*
	296	* Handling is done by creating a device and its callback and handling data
	297	* received via the SMBus host-notify address (0x8)
	298	*
	299	* This returns the client, which should be ultimately freed using
	300	* i2c_free_slave_host_notify_device(); or an ERRPTR to indicate an error.
	301	*/
	302	struct i2c_client i2c_new_slave_host_notify_device(struct i2c_adapter adapter)
	303	{
	304	struct i2c_board_info host_notify_board_info = {
	305	I2C_BOARD_INFO("smbus_host_notify", 0x08),
	306	.flags = I2C_CLIENT_SLAVE,
	307	};
	308	struct i2c_slave_host_notify_status *status;
	309	struct i2c_client *client;
	310	int ret;
	311
	312	status = kzalloc(sizeof(struct i2c_slave_host_notify_status),
313	GFP_KERNEL);
314	if (!status)
315	return ERR_PTR(-ENOMEM);
316
317	host_notify_board_info.platform_data = status;
318
319	client = i2c_new_client_device(adapter, &host_notify_board_info);
320	if (IS_ERR(client)) {
321	kfree(status);
322	return client;
323	}
324
325	ret = i2c_slave_register(client, i2c_slave_host_notify_cb);
326	if (ret) {
327	i2c_unregister_device(client);
328	kfree(status);
329	return ERR_PTR(ret);
330	}
331
332	return client;
333	}
334	EXPORT_SYMBOL_GPL(i2c_new_slave_host_notify_device);
335
336	/**
337	* i2c_free_slave_host_notify_device - free the client for SMBus host-notify
338	* support
339	* @client: the client to free
340	* Context: can sleep
341	*
342	* Free the i2c_client allocated via i2c_new_slave_host_notify_device
343	*/
344	void i2c_free_slave_host_notify_device(struct i2c_client *client)
345	{
346	if (IS_ERR_OR_NULL(client))
347	return;
348
349	i2c_slave_unregister(client);
350	kfree(client->dev.platform_data);
351	i2c_unregister_device(client);
352	}
353	EXPORT_SYMBOL_GPL(i2c_free_slave_host_notify_device);
354	#endif
355
5ace6085 JD	356	/*
	357	* SPD is not part of SMBus but we include it here for convenience as the
	358	* target systems are the same.
	359	* Restrictions to automatic SPD instantiation:
	360	* - Only works if all filled slots have the same memory type
84d47735	361	* - Only works for (LP)DDR memory types up to DDR5
13e3a512	362	* - Only works on systems with 1 to 8 memory slots
5ace6085 JD	363	*/
	364	#if IS_ENABLED(CONFIG_DMI)
	365	void i2c_register_spd(struct i2c_adapter *adap)
	366	{
	367	int n, slot_count = 0, dimm_count = 0;
	368	u16 handle;
	369	u8 common_mem_type = 0x0, mem_type;
	370	u64 mem_size;
	371	const char *name;
	372
	373	while ((handle = dmi_memdev_handle(slot_count)) != 0xffff) {
	374	slot_count++;
	375
	376	/* Skip empty slots */
	377	mem_size = dmi_memdev_size(handle);
	378	if (!mem_size)
	379	continue;
	380
	381	/* Skip undefined memory type */
	382	mem_type = dmi_memdev_type(handle);
	383	if (mem_type <= 0x02) /* Invalid, Other, Unknown */
	384	continue;
	385
	386	if (!common_mem_type) {
	387	/* First filled slot */
	388	common_mem_type = mem_type;
	389	} else {
	390	/* Check that all filled slots have the same type */
	391	if (mem_type != common_mem_type) {
	392	dev_warn(&adap->dev,
	393	"Different memory types mixed, not instantiating SPD\n");
	394	return;
	395	}
	396	}
	397	dimm_count++;
	398	}
	399
	400	/* No useful DMI data, bail out */
	401	if (!dimm_count)
	402	return;
	403
8821c837	404	/*
8f3075cc TW	405	* The max number of SPD EEPROMs that can be addressed per bus is 8.
	406	* If more slots are present either muxed or multiple busses are
	407	* necessary or the additional slots are ignored.
8821c837	408	*/
8f3075cc	409	slot_count = min(slot_count, 8);
5ace6085	410
3d50b95b CL	411	/*
	412	* Memory types could be found at section 7.18.2 (Memory Device — Type), table 78
	413	* https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.6.0.pdf
	414	*/
5ace6085	415	switch (common_mem_type) {
3d50b95b	416	case 0x12: /* DDR */
5ace6085 JD	417	case 0x13: /* DDR2 */
5ace6085 JD	418	case 0x18: /* DDR3 */
3d50b95b	419	case 0x1B: /* LPDDR */
5ace6085 JD	420	case 0x1C: /* LPDDR2 */
	421	case 0x1D: /* LPDDR3 */
	422	name = "spd";
	423	break;
	424	case 0x1A: /* DDR4 */
	425	case 0x1E: /* LPDDR4 */
	426	name = "ee1004";
	427	break;
84d47735 GR	428	case 0x22: /* DDR5 */
	429	case 0x23: /* LPDDR5 */
	430	name = "spd5118";
	431	break;
5ace6085 JD	432	default:
	433	dev_info(&adap->dev,
	434	"Memory type 0x%02x not supported yet, not instantiating SPD\n",
	435	common_mem_type);
	436	return;
	437	}
	438
	439	/*
	440	* We don't know in which slots the memory modules are. We could
	441	* try to guess from the slot names, but that would be rather complex
	442	* and unreliable, so better probe all possible addresses until we
	443	* have found all memory modules.
	444	*/
	445	for (n = 0; n < slot_count && dimm_count; n++) {
	446	struct i2c_board_info info;
	447	unsigned short addr_list[2];
	448
	449	memset(&info, 0, sizeof(struct i2c_board_info));
0b0221d9	450	strscpy(info.type, name, I2C_NAME_SIZE);
5ace6085 JD	451	addr_list[0] = 0x50 + n;
	452	addr_list[1] = I2C_CLIENT_END;
	453
	454	if (!IS_ERR(i2c_new_scanned_device(adap, &info, addr_list, NULL))) {
	455	dev_info(&adap->dev,
	456	"Successfully instantiated SPD at 0x%hx\n",
	457	addr_list[0]);
	458	dimm_count--;
	459	}
	460	}
	461	}
	462	EXPORT_SYMBOL_GPL(i2c_register_spd);
	463	#endif
	464
7c81c60f	465	MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
b5527a77 JD	466	MODULE_DESCRIPTION("SMBus protocol extensions support");
b5527a77 JD	467	MODULE_LICENSE("GPL");