[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 IP blocks can only detect one I2C slave address anyhow, this
 * driver does not support simulating EEPROM types which take more than one
 * address. It is prepared to simulate bigger EEPROMs with an internal 16 bit
 * pointer, yet implementation is deferred until the need actually arises.
 */

#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;
	bool first_write;
	spinlock_t buffer_lock;
	u8 buffer_idx;
	u8 buffer[];
};

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->first_write) {
			eeprom->buffer_idx = *val;
			eeprom->first_write = false;
		} else {
			spin_lock(&eeprom->buffer_lock);
			eeprom->buffer[eeprom->buffer_idx++] = *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];
		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->first_write = true;
		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(container_of(kobj, struct device, 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(container_of(kobj, struct device, 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_eeprom_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
	struct eeprom_data *eeprom;
	int ret;
	unsigned size = id->driver_data;

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

	eeprom->first_write = true;
	spin_lock_init(&eeprom->buffer_lock);
	i2c_set_clientdata(client, eeprom);

	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", 2048 / 8 },
	{ }
};
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	*
389be323 WS	8	* Because most IP blocks can only detect one I2C slave address anyhow, this
	9	* driver does not support simulating EEPROM types which take more than one
	10	* address. It is prepared to simulate bigger EEPROMs with an internal 16 bit
	11	* pointer, yet implementation is deferred until the need actually arises.
	12	*/
	13
	14	#include <linux/i2c.h>
	15	#include <linux/init.h>
	16	#include <linux/module.h>
	17	#include <linux/of.h>
	18	#include <linux/slab.h>
	19	#include <linux/spinlock.h>
	20	#include <linux/sysfs.h>
	21
	22	struct eeprom_data {
	23	struct bin_attribute bin;
	24	bool first_write;
	25	spinlock_t buffer_lock;
	26	u8 buffer_idx;
	27	u8 buffer[];
	28	};
	29
	30	static int i2c_slave_eeprom_slave_cb(struct i2c_client *client,
	31	enum i2c_slave_event event, u8 *val)
	32	{
	33	struct eeprom_data *eeprom = i2c_get_clientdata(client);
	34
	35	switch (event) {
5b77d162	36	case I2C_SLAVE_WRITE_RECEIVED:
389be323 WS	37	if (eeprom->first_write) {
	38	eeprom->buffer_idx = *val;
	39	eeprom->first_write = false;
	40	} else {
	41	spin_lock(&eeprom->buffer_lock);
	42	eeprom->buffer[eeprom->buffer_idx++] = *val;
	43	spin_unlock(&eeprom->buffer_lock);
	44	}
	45	break;
	46
5b77d162	47	case I2C_SLAVE_READ_PROCESSED:
98e982b3	48	/* The previous byte made it to the bus, get next one */
5b77d162 WS	49	eeprom->buffer_idx++;
	50	/* fallthrough */
	51	case I2C_SLAVE_READ_REQUESTED:
389be323 WS	52	spin_lock(&eeprom->buffer_lock);
	53	*val = eeprom->buffer[eeprom->buffer_idx];
	54	spin_unlock(&eeprom->buffer_lock);
98e982b3 WS	55	/*
	56	* Do not increment buffer_idx here, because we don't know if
	57	* this byte will be actually used. Read Linux I2C slave docs
	58	* for details.
	59	*/
389be323 WS	60	break;
389be323 WS	61
389be323	62	case I2C_SLAVE_STOP:
5b77d162	63	case I2C_SLAVE_WRITE_REQUESTED:
389be323 WS	64	eeprom->first_write = true;
	65	break;
	66
	67	default:
	68	break;
	69	}
	70
	71	return 0;
	72	}
	73
	74	static ssize_t i2c_slave_eeprom_bin_read(struct file filp, struct kobject kobj,
	75	struct bin_attribute attr, char buf, loff_t off, size_t count)
	76	{
	77	struct eeprom_data *eeprom;
	78	unsigned long flags;
	79
389be323 WS	80	eeprom = dev_get_drvdata(container_of(kobj, struct device, kobj));
	81
	82	spin_lock_irqsave(&eeprom->buffer_lock, flags);
	83	memcpy(buf, &eeprom->buffer[off], count);
	84	spin_unlock_irqrestore(&eeprom->buffer_lock, flags);
	85
	86	return count;
	87	}
	88
	89	static ssize_t i2c_slave_eeprom_bin_write(struct file filp, struct kobject kobj,
	90	struct bin_attribute attr, char buf, loff_t off, size_t count)
	91	{
	92	struct eeprom_data *eeprom;
	93	unsigned long flags;
	94
389be323 WS	95	eeprom = dev_get_drvdata(container_of(kobj, struct device, kobj));
	96
	97	spin_lock_irqsave(&eeprom->buffer_lock, flags);
	98	memcpy(&eeprom->buffer[off], buf, count);
	99	spin_unlock_irqrestore(&eeprom->buffer_lock, flags);
	100
	101	return count;
	102	}
	103
	104	static int i2c_slave_eeprom_probe(struct i2c_client client, const struct i2c_device_id id)
	105	{
	106	struct eeprom_data *eeprom;
	107	int ret;
	108	unsigned size = id->driver_data;
	109
	110	eeprom = devm_kzalloc(&client->dev, sizeof(struct eeprom_data) + size, GFP_KERNEL);
	111	if (!eeprom)
	112	return -ENOMEM;
	113
	114	eeprom->first_write = true;
	115	spin_lock_init(&eeprom->buffer_lock);
	116	i2c_set_clientdata(client, eeprom);
	117
	118	sysfs_bin_attr_init(&eeprom->bin);
	119	eeprom->bin.attr.name = "slave-eeprom";
	120	eeprom->bin.attr.mode = S_IRUSR \| S_IWUSR;
	121	eeprom->bin.read = i2c_slave_eeprom_bin_read;
	122	eeprom->bin.write = i2c_slave_eeprom_bin_write;
	123	eeprom->bin.size = size;
	124
	125	ret = sysfs_create_bin_file(&client->dev.kobj, &eeprom->bin);
	126	if (ret)
	127	return ret;
	128
	129	ret = i2c_slave_register(client, i2c_slave_eeprom_slave_cb);
	130	if (ret) {
	131	sysfs_remove_bin_file(&client->dev.kobj, &eeprom->bin);
	132	return ret;
	133	}
	134
	135	return 0;
	136	};
	137
	138	static int i2c_slave_eeprom_remove(struct i2c_client *client)
	139	{
	140	struct eeprom_data *eeprom = i2c_get_clientdata(client);
	141
	142	i2c_slave_unregister(client);
	143	sysfs_remove_bin_file(&client->dev.kobj, &eeprom->bin);
	144
	145	return 0;
	146	}
	147
	148	static const struct i2c_device_id i2c_slave_eeprom_id[] = {
	149	{ "slave-24c02", 2048 / 8 },
	150	{ }
	151	};
	152	MODULE_DEVICE_TABLE(i2c, i2c_slave_eeprom_id);
	153
	154	static struct i2c_driver i2c_slave_eeprom_driver = {
	155	.driver = {
	156	.name = "i2c-slave-eeprom",
389be323 WS	157	},
	158	.probe = i2c_slave_eeprom_probe,
	159	.remove = i2c_slave_eeprom_remove,
	160	.id_table = i2c_slave_eeprom_id,
	161	};
	162	module_i2c_driver(i2c_slave_eeprom_driver);
	163
	164	MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
	165	MODULE_DESCRIPTION("I2C slave mode EEPROM simulator");
	166	MODULE_LICENSE("GPL v2");