[linux-2.6-block.git] / drivers / i2c / i2c-slave-eeprom.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * I2C slave mode EEPROM simulator
 *
 * Copyright (C) 2014 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
 * Copyright (C) 2014 by Renesas Electronics Corporation
 *
 * Because most slave IP cores can only detect one I2C slave address anyhow,
 * this driver does not support simulating EEPROM types which take more than
 * one address.
 */

/*
 * FIXME: What to do if only 8 bits of a 16 bit address are sent?
 * The ST-M24C64 sends only 0xff then. Needs verification with other
 * EEPROMs, though. We currently use the 8 bit as a valid address.
 */

#include <linux/bitfield.h>
#include <linux/firmware.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/sysfs.h>

struct eeprom_data {
	struct bin_attribute bin;
	spinlock_t buffer_lock;
	u16 buffer_idx;
	u16 address_mask;
	u8 num_address_bytes;
	u8 idx_write_cnt;
	bool read_only;
	u8 buffer[];
};

#define I2C_SLAVE_BYTELEN GENMASK(15, 0)
#define I2C_SLAVE_FLAG_ADDR16 BIT(16)
#define I2C_SLAVE_FLAG_RO BIT(17)
#define I2C_SLAVE_DEVICE_MAGIC(_len, _flags) ((_flags) | ((_len) - 1))

static int i2c_slave_eeprom_slave_cb(struct i2c_client *client,
				     enum i2c_slave_event event, u8 *val)
{
	struct eeprom_data *eeprom = i2c_get_clientdata(client);

	switch (event) {
	case I2C_SLAVE_WRITE_RECEIVED:
		if (eeprom->idx_write_cnt < eeprom->num_address_bytes) {
			if (eeprom->idx_write_cnt == 0)
				eeprom->buffer_idx = 0;
			eeprom->buffer_idx = *val | (eeprom->buffer_idx << 8);
			eeprom->idx_write_cnt++;
		} else {
			if (!eeprom->read_only) {
				spin_lock(&eeprom->buffer_lock);
				eeprom->buffer[eeprom->buffer_idx++ & eeprom->address_mask] = *val;
				spin_unlock(&eeprom->buffer_lock);
			}
		}
		break;

	case I2C_SLAVE_READ_PROCESSED:
		/* The previous byte made it to the bus, get next one */
		eeprom->buffer_idx++;
		fallthrough;
	case I2C_SLAVE_READ_REQUESTED:
		spin_lock(&eeprom->buffer_lock);
		*val = eeprom->buffer[eeprom->buffer_idx & eeprom->address_mask];
		spin_unlock(&eeprom->buffer_lock);
		/*
		 * Do not increment buffer_idx here, because we don't know if
		 * this byte will be actually used. Read Linux I2C slave docs
		 * for details.
		 */
		break;

	case I2C_SLAVE_STOP:
	case I2C_SLAVE_WRITE_REQUESTED:
		eeprom->idx_write_cnt = 0;
		break;

	default:
		break;
	}

	return 0;
}

static ssize_t i2c_slave_eeprom_bin_read(struct file *filp, struct kobject *kobj,
		struct bin_attribute *attr, char *buf, loff_t off, size_t count)
{
	struct eeprom_data *eeprom;
	unsigned long flags;

	eeprom = dev_get_drvdata(kobj_to_dev(kobj));

	spin_lock_irqsave(&eeprom->buffer_lock, flags);
	memcpy(buf, &eeprom->buffer[off], count);
	spin_unlock_irqrestore(&eeprom->buffer_lock, flags);

	return count;
}

static ssize_t i2c_slave_eeprom_bin_write(struct file *filp, struct kobject *kobj,
		struct bin_attribute *attr, char *buf, loff_t off, size_t count)
{
	struct eeprom_data *eeprom;
	unsigned long flags;

	eeprom = dev_get_drvdata(kobj_to_dev(kobj));

	spin_lock_irqsave(&eeprom->buffer_lock, flags);
	memcpy(&eeprom->buffer[off], buf, count);
	spin_unlock_irqrestore(&eeprom->buffer_lock, flags);

	return count;
}

static int i2c_slave_init_eeprom_data(struct eeprom_data *eeprom, struct i2c_client *client,
				      unsigned int size)
{
	const struct firmware *fw;
	const char *eeprom_data;
	int ret = device_property_read_string(&client->dev, "firmware-name", &eeprom_data);

	if (!ret) {
		ret = request_firmware_into_buf(&fw, eeprom_data, &client->dev,
						eeprom->buffer, size);
		if (ret)
			return ret;
		release_firmware(fw);
	} else {
		/* An empty eeprom typically has all bits set to 1 */
		memset(eeprom->buffer, 0xff, size);
	}
	return 0;
}

static int i2c_slave_eeprom_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
	struct eeprom_data *eeprom;
	int ret;
	unsigned int size = FIELD_GET(I2C_SLAVE_BYTELEN, id->driver_data) + 1;
	unsigned int flag_addr16 = FIELD_GET(I2C_SLAVE_FLAG_ADDR16, id->driver_data);

	eeprom = devm_kzalloc(&client->dev, sizeof(struct eeprom_data) + size, GFP_KERNEL);
	if (!eeprom)
		return -ENOMEM;

	eeprom->num_address_bytes = flag_addr16 ? 2 : 1;
	eeprom->address_mask = size - 1;
	eeprom->read_only = FIELD_GET(I2C_SLAVE_FLAG_RO, id->driver_data);
	spin_lock_init(&eeprom->buffer_lock);
	i2c_set_clientdata(client, eeprom);

	ret = i2c_slave_init_eeprom_data(eeprom, client, size);
	if (ret)
		return ret;

	sysfs_bin_attr_init(&eeprom->bin);
	eeprom->bin.attr.name = "slave-eeprom";
	eeprom->bin.attr.mode = S_IRUSR | S_IWUSR;
	eeprom->bin.read = i2c_slave_eeprom_bin_read;
	eeprom->bin.write = i2c_slave_eeprom_bin_write;
	eeprom->bin.size = size;

	ret = sysfs_create_bin_file(&client->dev.kobj, &eeprom->bin);
	if (ret)
		return ret;

	ret = i2c_slave_register(client, i2c_slave_eeprom_slave_cb);
	if (ret) {
		sysfs_remove_bin_file(&client->dev.kobj, &eeprom->bin);
		return ret;
	}

	return 0;
};

static int i2c_slave_eeprom_remove(struct i2c_client *client)
{
	struct eeprom_data *eeprom = i2c_get_clientdata(client);

	i2c_slave_unregister(client);
	sysfs_remove_bin_file(&client->dev.kobj, &eeprom->bin);

	return 0;
}

static const struct i2c_device_id i2c_slave_eeprom_id[] = {
	{ "slave-24c02", I2C_SLAVE_DEVICE_MAGIC(2048 / 8,  0) },
	{ "slave-24c02ro", I2C_SLAVE_DEVICE_MAGIC(2048 / 8,  I2C_SLAVE_FLAG_RO) },
	{ "slave-24c32", I2C_SLAVE_DEVICE_MAGIC(32768 / 8, I2C_SLAVE_FLAG_ADDR16) },
	{ "slave-24c32ro", I2C_SLAVE_DEVICE_MAGIC(32768 / 8, I2C_SLAVE_FLAG_ADDR16 | I2C_SLAVE_FLAG_RO) },
	{ "slave-24c64", I2C_SLAVE_DEVICE_MAGIC(65536 / 8, I2C_SLAVE_FLAG_ADDR16) },
	{ "slave-24c64ro", I2C_SLAVE_DEVICE_MAGIC(65536 / 8, I2C_SLAVE_FLAG_ADDR16 | I2C_SLAVE_FLAG_RO) },
	{ "slave-24c512", I2C_SLAVE_DEVICE_MAGIC(524288 / 8, I2C_SLAVE_FLAG_ADDR16) },
	{ "slave-24c512ro", I2C_SLAVE_DEVICE_MAGIC(524288 / 8, I2C_SLAVE_FLAG_ADDR16 | I2C_SLAVE_FLAG_RO) },
	{ }
};
MODULE_DEVICE_TABLE(i2c, i2c_slave_eeprom_id);

static struct i2c_driver i2c_slave_eeprom_driver = {
	.driver = {
		.name = "i2c-slave-eeprom",
	},
	.probe = i2c_slave_eeprom_probe,
	.remove = i2c_slave_eeprom_remove,
	.id_table = i2c_slave_eeprom_id,
};
module_i2c_driver(i2c_slave_eeprom_driver);

MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
MODULE_DESCRIPTION("I2C slave mode EEPROM simulator");
MODULE_LICENSE("GPL v2");
Commit	Line	Data
b886d83c	1	// SPDX-License-Identifier: GPL-2.0-only
389be323 WS	2	/*
	3	* I2C slave mode EEPROM simulator
	4	*
	5	* Copyright (C) 2014 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
	6	* Copyright (C) 2014 by Renesas Electronics Corporation
	7	*
468ed57f WS	8	* Because most slave IP cores can only detect one I2C slave address anyhow,
	9	* this driver does not support simulating EEPROM types which take more than
	10	* one address.
389be323 WS	11	*/
389be323 WS	12
fe050f99 BA	13	/*
	14	* FIXME: What to do if only 8 bits of a 16 bit address are sent?
	15	* The ST-M24C64 sends only 0xff then. Needs verification with other
	16	* EEPROMs, though. We currently use the 8 bit as a valid address.
	17	*/
	18
82d51481	19	#include <linux/bitfield.h>
e804f0a7	20	#include <linux/firmware.h>
389be323 WS	21	#include <linux/i2c.h>
	22	#include <linux/init.h>
	23	#include <linux/module.h>
	24	#include <linux/of.h>
	25	#include <linux/slab.h>
	26	#include <linux/spinlock.h>
	27	#include <linux/sysfs.h>
	28
	29	struct eeprom_data {
	30	struct bin_attribute bin;
389be323	31	spinlock_t buffer_lock;
82d51481 BA	32	u16 buffer_idx;
	33	u16 address_mask;
	34	u8 num_address_bytes;
	35	u8 idx_write_cnt;
11af27f4	36	bool read_only;
389be323 WS	37	u8 buffer[];
	38	};
	39
82d51481 BA	40	#define I2C_SLAVE_BYTELEN GENMASK(15, 0)
82d51481 BA	41	#define I2C_SLAVE_FLAG_ADDR16 BIT(16)
11af27f4	42	#define I2C_SLAVE_FLAG_RO BIT(17)
5c71ca4d	43	#define I2C_SLAVE_DEVICE_MAGIC(_len, _flags) ((_flags) \| ((_len) - 1))
82d51481	44
389be323 WS	45	static int i2c_slave_eeprom_slave_cb(struct i2c_client *client,
	46	enum i2c_slave_event event, u8 *val)
	47	{
	48	struct eeprom_data *eeprom = i2c_get_clientdata(client);
	49
	50	switch (event) {
5b77d162	51	case I2C_SLAVE_WRITE_RECEIVED:
82d51481 BA	52	if (eeprom->idx_write_cnt < eeprom->num_address_bytes) {
	53	if (eeprom->idx_write_cnt == 0)
	54	eeprom->buffer_idx = 0;
	55	eeprom->buffer_idx = *val \| (eeprom->buffer_idx << 8);
	56	eeprom->idx_write_cnt++;
389be323	57	} else {
11af27f4 BA	58	if (!eeprom->read_only) {
	59	spin_lock(&eeprom->buffer_lock);
	60	eeprom->buffer[eeprom->buffer_idx++ & eeprom->address_mask] = *val;
	61	spin_unlock(&eeprom->buffer_lock);
	62	}
389be323 WS	63	}
	64	break;
	65
5b77d162	66	case I2C_SLAVE_READ_PROCESSED:
98e982b3	67	/* The previous byte made it to the bus, get next one */
5b77d162	68	eeprom->buffer_idx++;
4db7e178	69	fallthrough;
5b77d162	70	case I2C_SLAVE_READ_REQUESTED:
389be323	71	spin_lock(&eeprom->buffer_lock);
82d51481	72	*val = eeprom->buffer[eeprom->buffer_idx & eeprom->address_mask];
389be323	73	spin_unlock(&eeprom->buffer_lock);
98e982b3 WS	74	/*
	75	* Do not increment buffer_idx here, because we don't know if
	76	* this byte will be actually used. Read Linux I2C slave docs
	77	* for details.
	78	*/
389be323 WS	79	break;
389be323 WS	80
389be323	81	case I2C_SLAVE_STOP:
5b77d162	82	case I2C_SLAVE_WRITE_REQUESTED:
82d51481	83	eeprom->idx_write_cnt = 0;
389be323 WS	84	break;
	85
	86	default:
	87	break;
	88	}
	89
	90	return 0;
	91	}
	92
	93	static ssize_t i2c_slave_eeprom_bin_read(struct file filp, struct kobject kobj,
	94	struct bin_attribute attr, char buf, loff_t off, size_t count)
	95	{
	96	struct eeprom_data *eeprom;
	97	unsigned long flags;
	98
6b060d8a	99	eeprom = dev_get_drvdata(kobj_to_dev(kobj));
389be323 WS	100
	101	spin_lock_irqsave(&eeprom->buffer_lock, flags);
	102	memcpy(buf, &eeprom->buffer[off], count);
	103	spin_unlock_irqrestore(&eeprom->buffer_lock, flags);
	104
	105	return count;
	106	}
	107
	108	static ssize_t i2c_slave_eeprom_bin_write(struct file filp, struct kobject kobj,
	109	struct bin_attribute attr, char buf, loff_t off, size_t count)
	110	{
	111	struct eeprom_data *eeprom;
	112	unsigned long flags;
	113
6b060d8a	114	eeprom = dev_get_drvdata(kobj_to_dev(kobj));
389be323 WS	115
	116	spin_lock_irqsave(&eeprom->buffer_lock, flags);
	117	memcpy(&eeprom->buffer[off], buf, count);
	118	spin_unlock_irqrestore(&eeprom->buffer_lock, flags);
	119
	120	return count;
	121	}
	122
e804f0a7 BA	123	static int i2c_slave_init_eeprom_data(struct eeprom_data eeprom, struct i2c_client client,
	124	unsigned int size)
	125	{
	126	const struct firmware *fw;
	127	const char *eeprom_data;
	128	int ret = device_property_read_string(&client->dev, "firmware-name", &eeprom_data);
	129
	130	if (!ret) {
	131	ret = request_firmware_into_buf(&fw, eeprom_data, &client->dev,
	132	eeprom->buffer, size);
	133	if (ret)
	134	return ret;
	135	release_firmware(fw);
	136	} else {
	137	/* An empty eeprom typically has all bits set to 1 */
	138	memset(eeprom->buffer, 0xff, size);
	139	}
	140	return 0;
	141	}
	142
389be323 WS	143	static int i2c_slave_eeprom_probe(struct i2c_client client, const struct i2c_device_id id)
	144	{
	145	struct eeprom_data *eeprom;
	146	int ret;
5c71ca4d	147	unsigned int size = FIELD_GET(I2C_SLAVE_BYTELEN, id->driver_data) + 1;
82d51481	148	unsigned int flag_addr16 = FIELD_GET(I2C_SLAVE_FLAG_ADDR16, id->driver_data);
389be323 WS	149
	150	eeprom = devm_kzalloc(&client->dev, sizeof(struct eeprom_data) + size, GFP_KERNEL);
	151	if (!eeprom)
	152	return -ENOMEM;
	153
82d51481 BA	154	eeprom->num_address_bytes = flag_addr16 ? 2 : 1;
82d51481 BA	155	eeprom->address_mask = size - 1;
11af27f4	156	eeprom->read_only = FIELD_GET(I2C_SLAVE_FLAG_RO, id->driver_data);
389be323 WS	157	spin_lock_init(&eeprom->buffer_lock);
	158	i2c_set_clientdata(client, eeprom);
	159
e804f0a7 BA	160	ret = i2c_slave_init_eeprom_data(eeprom, client, size);
	161	if (ret)
	162	return ret;
	163
389be323 WS	164	sysfs_bin_attr_init(&eeprom->bin);
	165	eeprom->bin.attr.name = "slave-eeprom";
	166	eeprom->bin.attr.mode = S_IRUSR \| S_IWUSR;
	167	eeprom->bin.read = i2c_slave_eeprom_bin_read;
	168	eeprom->bin.write = i2c_slave_eeprom_bin_write;
	169	eeprom->bin.size = size;
	170
	171	ret = sysfs_create_bin_file(&client->dev.kobj, &eeprom->bin);
	172	if (ret)
	173	return ret;
	174
	175	ret = i2c_slave_register(client, i2c_slave_eeprom_slave_cb);
	176	if (ret) {
	177	sysfs_remove_bin_file(&client->dev.kobj, &eeprom->bin);
	178	return ret;
	179	}
	180
	181	return 0;
	182	};
	183
	184	static int i2c_slave_eeprom_remove(struct i2c_client *client)
	185	{
	186	struct eeprom_data *eeprom = i2c_get_clientdata(client);
	187
	188	i2c_slave_unregister(client);
	189	sysfs_remove_bin_file(&client->dev.kobj, &eeprom->bin);
	190
	191	return 0;
	192	}
	193
	194	static const struct i2c_device_id i2c_slave_eeprom_id[] = {
82d51481	195	{ "slave-24c02", I2C_SLAVE_DEVICE_MAGIC(2048 / 8, 0) },
11af27f4	196	{ "slave-24c02ro", I2C_SLAVE_DEVICE_MAGIC(2048 / 8, I2C_SLAVE_FLAG_RO) },
82d51481	197	{ "slave-24c32", I2C_SLAVE_DEVICE_MAGIC(32768 / 8, I2C_SLAVE_FLAG_ADDR16) },
11af27f4	198	{ "slave-24c32ro", I2C_SLAVE_DEVICE_MAGIC(32768 / 8, I2C_SLAVE_FLAG_ADDR16 \| I2C_SLAVE_FLAG_RO) },
82d51481	199	{ "slave-24c64", I2C_SLAVE_DEVICE_MAGIC(65536 / 8, I2C_SLAVE_FLAG_ADDR16) },
11af27f4	200	{ "slave-24c64ro", I2C_SLAVE_DEVICE_MAGIC(65536 / 8, I2C_SLAVE_FLAG_ADDR16 \| I2C_SLAVE_FLAG_RO) },
5c71ca4d WS	201	{ "slave-24c512", I2C_SLAVE_DEVICE_MAGIC(524288 / 8, I2C_SLAVE_FLAG_ADDR16) },
5c71ca4d WS	202	{ "slave-24c512ro", I2C_SLAVE_DEVICE_MAGIC(524288 / 8, I2C_SLAVE_FLAG_ADDR16 \| I2C_SLAVE_FLAG_RO) },
389be323 WS	203	{ }
	204	};
	205	MODULE_DEVICE_TABLE(i2c, i2c_slave_eeprom_id);
	206
	207	static struct i2c_driver i2c_slave_eeprom_driver = {
	208	.driver = {
	209	.name = "i2c-slave-eeprom",
389be323 WS	210	},
	211	.probe = i2c_slave_eeprom_probe,
	212	.remove = i2c_slave_eeprom_remove,
	213	.id_table = i2c_slave_eeprom_id,
	214	};
	215	module_i2c_driver(i2c_slave_eeprom_driver);
	216
	217	MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
	218	MODULE_DESCRIPTION("I2C slave mode EEPROM simulator");
	219	MODULE_LICENSE("GPL v2");