Initial import

1 files changed, 719 insertions, 0 deletions

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
new file mode 100644
index 000000000..2d3db81be
--- /dev/null
+++ b/drivers/misc/eeprom/at24.c
@@ -0,0 +1,719 @@
+/*
+ * at24.c - handle most I2C EEPROMs
+ *
+ * Copyright (C) 2005-2007 David Brownell
+ * Copyright (C) 2008 Wolfram Sang, Pengutronix
+ *
+ * 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.
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/mutex.h>
+#include <linux/sysfs.h>
+#include <linux/mod_devicetable.h>
+#include <linux/log2.h>
+#include <linux/bitops.h>
+#include <linux/jiffies.h>
+#include <linux/of.h>
+#include <linux/i2c.h>
+#include <linux/platform_data/at24.h>
+
+/*
+ * I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
+ * Differences between different vendor product lines (like Atmel AT24C or
+ * MicroChip 24LC, etc) won't much matter for typical read/write access.
+ * There are also I2C RAM chips, likewise interchangeable. One example
+ * would be the PCF8570, which acts like a 24c02 EEPROM (256 bytes).
+ *
+ * However, misconfiguration can lose data. "Set 16-bit memory address"
+ * to a part with 8-bit addressing will overwrite data. Writing with too
+ * big a page size also loses data. And it's not safe to assume that the
+ * conventional addresses 0x50..0x57 only hold eeproms; a PCF8563 RTC
+ * uses 0x51, for just one example.
+ *
+ * Accordingly, explicit board-specific configuration data should be used
+ * in almost all cases. (One partial exception is an SMBus used to access
+ * "SPD" data for DRAM sticks. Those only use 24c02 EEPROMs.)
+ *
+ * So this driver uses "new style" I2C driver binding, expecting to be
+ * told what devices exist. That may be in arch/X/mach-Y/board-Z.c or
+ * similar kernel-resident tables; or, configuration data coming from
+ * a bootloader.
+ *
+ * Other than binding model, current differences from "eeprom" driver are
+ * that this one handles write access and isn't restricted to 24c02 devices.
+ * It also handles larger devices (32 kbit and up) with two-byte addresses,
+ * which won't work on pure SMBus systems.
+ */
+
+struct at24_data {
+	struct at24_platform_data chip;
+	struct memory_accessor macc;
+	int use_smbus;
+	int use_smbus_write;
+
+	/*
+	 * Lock protects against activities from other Linux tasks,
+	 * but not from changes by other I2C masters.
+	 */
+	struct mutex lock;
+	struct bin_attribute bin;
+
+	u8 *writebuf;
+	unsigned write_max;
+	unsigned num_addresses;
+
+	/*
+	 * Some chips tie up multiple I2C addresses; dummy devices reserve
+	 * them for us, and we'll use them with SMBus calls.
+	 */
+	struct i2c_client *client[];
+};
+
+/*
+ * This parameter is to help this driver avoid blocking other drivers out
+ * of I2C for potentially troublesome amounts of time. With a 100 kHz I2C
+ * clock, one 256 byte read takes about 1/43 second which is excessive;
+ * but the 1/170 second it takes at 400 kHz may be quite reasonable; and
+ * at 1 MHz (Fm+) a 1/430 second delay could easily be invisible.
+ *
+ * This value is forced to be a power of two so that writes align on pages.
+ */
+static unsigned io_limit = 128;
+module_param(io_limit, uint, 0);
+MODULE_PARM_DESC(io_limit, "Maximum bytes per I/O (default 128)");
+
+/*
+ * Specs often allow 5 msec for a page write, sometimes 20 msec;
+ * it's important to recover from write timeouts.
+ */
+static unsigned write_timeout = 25;
+module_param(write_timeout, uint, 0);
+MODULE_PARM_DESC(write_timeout, "Time (in ms) to try writes (default 25)");
+
+#define AT24_SIZE_BYTELEN 5
+#define AT24_SIZE_FLAGS 8
+
+#define AT24_BITMASK(x) (BIT(x) - 1)
+
+/* create non-zero magic value for given eeprom parameters */
+#define AT24_DEVICE_MAGIC(_len, _flags) 		\
+	((1 << AT24_SIZE_FLAGS | (_flags)) 		\
+	    << AT24_SIZE_BYTELEN | ilog2(_len))
+
+static const struct i2c_device_id at24_ids[] = {
+	/* needs 8 addresses as A0-A2 are ignored */
+	{ "24c00", AT24_DEVICE_MAGIC(128 / 8, AT24_FLAG_TAKE8ADDR) },
+	/* old variants can't be handled with this generic entry! */
+	{ "24c01", AT24_DEVICE_MAGIC(1024 / 8, 0) },
+	{ "24c02", AT24_DEVICE_MAGIC(2048 / 8, 0) },
+	/* spd is a 24c02 in memory DIMMs */
+	{ "spd", AT24_DEVICE_MAGIC(2048 / 8,
+		AT24_FLAG_READONLY | AT24_FLAG_IRUGO) },
+	{ "24c04", AT24_DEVICE_MAGIC(4096 / 8, 0) },
+	/* 24rf08 quirk is handled at i2c-core */
+	{ "24c08", AT24_DEVICE_MAGIC(8192 / 8, 0) },
+	{ "24c16", AT24_DEVICE_MAGIC(16384 / 8, 0) },
+	{ "24c32", AT24_DEVICE_MAGIC(32768 / 8, AT24_FLAG_ADDR16) },
+	{ "24c64", AT24_DEVICE_MAGIC(65536 / 8, AT24_FLAG_ADDR16) },
+	{ "24c128", AT24_DEVICE_MAGIC(131072 / 8, AT24_FLAG_ADDR16) },
+	{ "24c256", AT24_DEVICE_MAGIC(262144 / 8, AT24_FLAG_ADDR16) },
+	{ "24c512", AT24_DEVICE_MAGIC(524288 / 8, AT24_FLAG_ADDR16) },
+	{ "24c1024", AT24_DEVICE_MAGIC(1048576 / 8, AT24_FLAG_ADDR16) },
+	{ "at24", 0 },
+	{ /* END OF LIST */ }
+};
+MODULE_DEVICE_TABLE(i2c, at24_ids);
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * This routine supports chips which consume multiple I2C addresses. It
+ * computes the addressing information to be used for a given r/w request.
+ * Assumes that sanity checks for offset happened at sysfs-layer.
+ */
+static struct i2c_client *at24_translate_offset(struct at24_data *at24,
+		unsigned *offset)
+{
+	unsigned i;
+
+	if (at24->chip.flags & AT24_FLAG_ADDR16) {
+		i = *offset >> 16;
+		*offset &= 0xffff;
+	} else {
+		i = *offset >> 8;
+		*offset &= 0xff;
+	}
+
+	return at24->client[i];
+}
+
+static ssize_t at24_eeprom_read(struct at24_data *at24, char *buf,
+		unsigned offset, size_t count)
+{
+	struct i2c_msg msg[2];
+	u8 msgbuf[2];
+	struct i2c_client *client;
+	unsigned long timeout, read_time;
+	int status, i;
+
+	memset(msg, 0, sizeof(msg));
+
+	/*
+	 * REVISIT some multi-address chips don't rollover page reads to
+	 * the next slave address, so we may need to truncate the count.
+	 * Those chips might need another quirk flag.
+	 *
+	 * If the real hardware used four adjacent 24c02 chips and that
+	 * were misconfigured as one 24c08, that would be a similar effect:
+	 * one "eeprom" file not four, but larger reads would fail when
+	 * they crossed certain pages.
+	 */
+
+	/*
+	 * Slave address and byte offset derive from the offset. Always
+	 * set the byte address; on a multi-master board, another master
+	 * may have changed the chip's "current" address pointer.
+	 */
+	client = at24_translate_offset(at24, &offset);
+
+	if (count > io_limit)
+		count = io_limit;
+
+	switch (at24->use_smbus) {
+	case I2C_SMBUS_I2C_BLOCK_DATA:
+		/* Smaller eeproms can work given some SMBus extension calls */
+		if (count > I2C_SMBUS_BLOCK_MAX)
+			count = I2C_SMBUS_BLOCK_MAX;
+		break;
+	case I2C_SMBUS_WORD_DATA:
+		count = 2;
+		break;
+	case I2C_SMBUS_BYTE_DATA:
+		count = 1;
+		break;
+	default:
+		/*
+		 * When we have a better choice than SMBus calls, use a
+		 * combined I2C message. Write address; then read up to
+		 * io_limit data bytes. Note that read page rollover helps us
+		 * here (unlike writes). msgbuf is u8 and will cast to our
+		 * needs.
+		 */
+		i = 0;
+		if (at24->chip.flags & AT24_FLAG_ADDR16)
+			msgbuf[i++] = offset >> 8;
+		msgbuf[i++] = offset;
+
+		msg[0].addr = client->addr;
+		msg[0].buf = msgbuf;
+		msg[0].len = i;
+
+		msg[1].addr = client->addr;
+		msg[1].flags = I2C_M_RD;
+		msg[1].buf = buf;
+		msg[1].len = count;
+	}
+
+	/*
+	 * Reads fail if the previous write didn't complete yet. We may
+	 * loop a few times until this one succeeds, waiting at least
+	 * long enough for one entire page write to work.
+	 */
+	timeout = jiffies + msecs_to_jiffies(write_timeout);
+	do {
+		read_time = jiffies;
+		switch (at24->use_smbus) {
+		case I2C_SMBUS_I2C_BLOCK_DATA:
+			status = i2c_smbus_read_i2c_block_data(client, offset,
+					count, buf);
+			break;
+		case I2C_SMBUS_WORD_DATA:
+			status = i2c_smbus_read_word_data(client, offset);
+			if (status >= 0) {
+				buf[0] = status & 0xff;
+				buf[1] = status >> 8;
+				status = count;
+			}
+			break;
+		case I2C_SMBUS_BYTE_DATA:
+			status = i2c_smbus_read_byte_data(client, offset);
+			if (status >= 0) {
+				buf[0] = status;
+				status = count;
+			}
+			break;
+		default:
+			status = i2c_transfer(client->adapter, msg, 2);
+			if (status == 2)
+				status = count;
+		}
+		dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n",
+				count, offset, status, jiffies);
+
+		if (status == count)
+			return count;
+
+		/* REVISIT: at HZ=100, this is sloooow */
+		msleep(1);
+	} while (time_before(read_time, timeout));
+
+	return -ETIMEDOUT;
+}
+
+static ssize_t at24_read(struct at24_data *at24,
+		char *buf, loff_t off, size_t count)
+{
+	ssize_t retval = 0;
+
+	if (unlikely(!count))
+		return count;
+
+	/*
+	 * Read data from chip, protecting against concurrent updates
+	 * from this host, but not from other I2C masters.
+	 */
+	mutex_lock(&at24->lock);
+
+	while (count) {
+		ssize_t	status;
+
+		status = at24_eeprom_read(at24, buf, off, count);
+		if (status <= 0) {
+			if (retval == 0)
+				retval = status;
+			break;
+		}
+		buf += status;
+		off += status;
+		count -= status;
+		retval += status;
+	}
+
+	mutex_unlock(&at24->lock);
+
+	return retval;
+}
+
+static ssize_t at24_bin_read(struct file *filp, struct kobject *kobj,
+		struct bin_attribute *attr,
+		char *buf, loff_t off, size_t count)
+{
+	struct at24_data *at24;
+
+	at24 = dev_get_drvdata(container_of(kobj, struct device, kobj));
+	return at24_read(at24, buf, off, count);
+}
+
+
+/*
+ * Note that if the hardware write-protect pin is pulled high, the whole
+ * chip is normally write protected. But there are plenty of product
+ * variants here, including OTP fuses and partial chip protect.
+ *
+ * We only use page mode writes; the alternative is sloooow. This routine
+ * writes at most one page.
+ */
+static ssize_t at24_eeprom_write(struct at24_data *at24, const char *buf,
+		unsigned offset, size_t count)
+{
+	struct i2c_client *client;
+	struct i2c_msg msg;
+	ssize_t status = 0;
+	unsigned long timeout, write_time;
+	unsigned next_page;
+
+	/* Get corresponding I2C address and adjust offset */
+	client = at24_translate_offset(at24, &offset);
+
+	/* write_max is at most a page */
+	if (count > at24->write_max)
+		count = at24->write_max;
+
+	/* Never roll over backwards, to the start of this page */
+	next_page = roundup(offset + 1, at24->chip.page_size);
+	if (offset + count > next_page)
+		count = next_page - offset;
+
+	/* If we'll use I2C calls for I/O, set up the message */
+	if (!at24->use_smbus) {
+		int i = 0;
+
+		msg.addr = client->addr;
+		msg.flags = 0;
+
+		/* msg.buf is u8 and casts will mask the values */
+		msg.buf = at24->writebuf;
+		if (at24->chip.flags & AT24_FLAG_ADDR16)
+			msg.buf[i++] = offset >> 8;
+
+		msg.buf[i++] = offset;
+		memcpy(&msg.buf[i], buf, count);
+		msg.len = i + count;
+	}
+
+	/*
+	 * Writes fail if the previous one didn't complete yet. We may
+	 * loop a few times until this one succeeds, waiting at least
+	 * long enough for one entire page write to work.
+	 */
+	timeout = jiffies + msecs_to_jiffies(write_timeout);
+	do {
+		write_time = jiffies;
+		if (at24->use_smbus_write) {
+			switch (at24->use_smbus_write) {
+			case I2C_SMBUS_I2C_BLOCK_DATA:
+				status = i2c_smbus_write_i2c_block_data(client,
+						offset, count, buf);
+				break;
+			case I2C_SMBUS_BYTE_DATA:
+				status = i2c_smbus_write_byte_data(client,
+						offset, buf[0]);
+				break;
+			}
+
+			if (status == 0)
+				status = count;
+		} else {
+			status = i2c_transfer(client->adapter, &msg, 1);
+			if (status == 1)
+				status = count;
+		}
+		dev_dbg(&client->dev, "write %zu@%d --> %zd (%ld)\n",
+				count, offset, status, jiffies);
+
+		if (status == count)
+			return count;
+
+		/* REVISIT: at HZ=100, this is sloooow */
+		msleep(1);
+	} while (time_before(write_time, timeout));
+
+	return -ETIMEDOUT;
+}
+
+static ssize_t at24_write(struct at24_data *at24, const char *buf, loff_t off,
+			  size_t count)
+{
+	ssize_t retval = 0;
+
+	if (unlikely(!count))
+		return count;
+
+	/*
+	 * Write data to chip, protecting against concurrent updates
+	 * from this host, but not from other I2C masters.
+	 */
+	mutex_lock(&at24->lock);
+
+	while (count) {
+		ssize_t	status;
+
+		status = at24_eeprom_write(at24, buf, off, count);
+		if (status <= 0) {
+			if (retval == 0)
+				retval = status;
+			break;
+		}
+		buf += status;
+		off += status;
+		count -= status;
+		retval += status;
+	}
+
+	mutex_unlock(&at24->lock);
+
+	return retval;
+}
+
+static ssize_t at24_bin_write(struct file *filp, struct kobject *kobj,
+		struct bin_attribute *attr,
+		char *buf, loff_t off, size_t count)
+{
+	struct at24_data *at24;
+
+	if (unlikely(off >= attr->size))
+		return -EFBIG;
+
+	at24 = dev_get_drvdata(container_of(kobj, struct device, kobj));
+	return at24_write(at24, buf, off, count);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * This lets other kernel code access the eeprom data. For example, it
+ * might hold a board's Ethernet address, or board-specific calibration
+ * data generated on the manufacturing floor.
+ */
+
+static ssize_t at24_macc_read(struct memory_accessor *macc, char *buf,
+			 off_t offset, size_t count)
+{
+	struct at24_data *at24 = container_of(macc, struct at24_data, macc);
+
+	return at24_read(at24, buf, offset, count);
+}
+
+static ssize_t at24_macc_write(struct memory_accessor *macc, const char *buf,
+			  off_t offset, size_t count)
+{
+	struct at24_data *at24 = container_of(macc, struct at24_data, macc);
+
+	return at24_write(at24, buf, offset, count);
+}
+
+/*-------------------------------------------------------------------------*/
+
+#ifdef CONFIG_OF
+static void at24_get_ofdata(struct i2c_client *client,
+		struct at24_platform_data *chip)
+{
+	const __be32 *val;
+	struct device_node *node = client->dev.of_node;
+
+	if (node) {
+		if (of_get_property(node, "read-only", NULL))
+			chip->flags |= AT24_FLAG_READONLY;
+		val = of_get_property(node, "pagesize", NULL);
+		if (val)
+			chip->page_size = be32_to_cpup(val);
+	}
+}
+#else
+static void at24_get_ofdata(struct i2c_client *client,
+		struct at24_platform_data *chip)
+{ }
+#endif /* CONFIG_OF */
+
+static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
+{
+	struct at24_platform_data chip;
+	bool writable;
+	int use_smbus = 0;
+	int use_smbus_write = 0;
+	struct at24_data *at24;
+	int err;
+	unsigned i, num_addresses;
+	kernel_ulong_t magic;
+
+	if (client->dev.platform_data) {
+		chip = *(struct at24_platform_data *)client->dev.platform_data;
+	} else {
+		if (!id->driver_data)
+			return -ENODEV;
+
+		magic = id->driver_data;
+		chip.byte_len = BIT(magic & AT24_BITMASK(AT24_SIZE_BYTELEN));
+		magic >>= AT24_SIZE_BYTELEN;
+		chip.flags = magic & AT24_BITMASK(AT24_SIZE_FLAGS);
+		/*
+		 * This is slow, but we can't know all eeproms, so we better
+		 * play safe. Specifying custom eeprom-types via platform_data
+		 * is recommended anyhow.
+		 */
+		chip.page_size = 1;
+
+		/* update chipdata if OF is present */
+		at24_get_ofdata(client, &chip);
+
+		chip.setup = NULL;
+		chip.context = NULL;
+	}
+
+	if (!is_power_of_2(chip.byte_len))
+		dev_warn(&client->dev,
+			"byte_len looks suspicious (no power of 2)!\n");
+	if (!chip.page_size) {
+		dev_err(&client->dev, "page_size must not be 0!\n");
+		return -EINVAL;
+	}
+	if (!is_power_of_2(chip.page_size))
+		dev_warn(&client->dev,
+			"page_size looks suspicious (no power of 2)!\n");
+
+	/* Use I2C operations unless we're stuck with SMBus extensions. */
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
+		if (chip.flags & AT24_FLAG_ADDR16)
+			return -EPFNOSUPPORT;
+
+		if (i2c_check_functionality(client->adapter,
+				I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
+			use_smbus = I2C_SMBUS_I2C_BLOCK_DATA;
+		} else if (i2c_check_functionality(client->adapter,
+				I2C_FUNC_SMBUS_READ_WORD_DATA)) {
+			use_smbus = I2C_SMBUS_WORD_DATA;
+		} else if (i2c_check_functionality(client->adapter,
+				I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
+			use_smbus = I2C_SMBUS_BYTE_DATA;
+		} else {
+			return -EPFNOSUPPORT;
+		}
+	}
+
+	/* Use I2C operations unless we're stuck with SMBus extensions. */
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
+		if (i2c_check_functionality(client->adapter,
+				I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)) {
+			use_smbus_write = I2C_SMBUS_I2C_BLOCK_DATA;
+		} else if (i2c_check_functionality(client->adapter,
+				I2C_FUNC_SMBUS_WRITE_BYTE_DATA)) {
+			use_smbus_write = I2C_SMBUS_BYTE_DATA;
+			chip.page_size = 1;
+		}
+	}
+
+	if (chip.flags & AT24_FLAG_TAKE8ADDR)
+		num_addresses = 8;
+	else
+		num_addresses =	DIV_ROUND_UP(chip.byte_len,
+			(chip.flags & AT24_FLAG_ADDR16) ? 65536 : 256);
+
+	at24 = devm_kzalloc(&client->dev, sizeof(struct at24_data) +
+		num_addresses * sizeof(struct i2c_client *), GFP_KERNEL);
+	if (!at24)
+		return -ENOMEM;
+
+	mutex_init(&at24->lock);
+	at24->use_smbus = use_smbus;
+	at24->use_smbus_write = use_smbus_write;
+	at24->chip = chip;
+	at24->num_addresses = num_addresses;
+
+	/*
+	 * Export the EEPROM bytes through sysfs, since that's convenient.
+	 * By default, only root should see the data (maybe passwords etc)
+	 */
+	sysfs_bin_attr_init(&at24->bin);
+	at24->bin.attr.name = "eeprom";
+	at24->bin.attr.mode = chip.flags & AT24_FLAG_IRUGO ? S_IRUGO : S_IRUSR;
+	at24->bin.read = at24_bin_read;
+	at24->bin.size = chip.byte_len;
+
+	at24->macc.read = at24_macc_read;
+
+	writable = !(chip.flags & AT24_FLAG_READONLY);
+	if (writable) {
+		if (!use_smbus || use_smbus_write) {
+
+			unsigned write_max = chip.page_size;
+
+			at24->macc.write = at24_macc_write;
+
+			at24->bin.write = at24_bin_write;
+			at24->bin.attr.mode |= S_IWUSR;
+
+			if (write_max > io_limit)
+				write_max = io_limit;
+			if (use_smbus && write_max > I2C_SMBUS_BLOCK_MAX)
+				write_max = I2C_SMBUS_BLOCK_MAX;
+			at24->write_max = write_max;
+
+			/* buffer (data + address at the beginning) */
+			at24->writebuf = devm_kzalloc(&client->dev,
+				write_max + 2, GFP_KERNEL);
+			if (!at24->writebuf)
+				return -ENOMEM;
+		} else {
+			dev_warn(&client->dev,
+				"cannot write due to controller restrictions.");
+		}
+	}
+
+	at24->client[0] = client;
+
+	/* use dummy devices for multiple-address chips */
+	for (i = 1; i < num_addresses; i++) {
+		at24->client[i] = i2c_new_dummy(client->adapter,
+					client->addr + i);
+		if (!at24->client[i]) {
+			dev_err(&client->dev, "address 0x%02x unavailable\n",
+					client->addr + i);
+			err = -EADDRINUSE;
+			goto err_clients;
+		}
+	}
+
+	err = sysfs_create_bin_file(&client->dev.kobj, &at24->bin);
+	if (err)
+		goto err_clients;
+
+	i2c_set_clientdata(client, at24);
+
+	dev_info(&client->dev, "%zu byte %s EEPROM, %s, %u bytes/write\n",
+		at24->bin.size, client->name,
+		writable ? "writable" : "read-only", at24->write_max);
+	if (use_smbus == I2C_SMBUS_WORD_DATA ||
+	    use_smbus == I2C_SMBUS_BYTE_DATA) {
+		dev_notice(&client->dev, "Falling back to %s reads, "
+			   "performance will suffer\n", use_smbus ==
+			   I2C_SMBUS_WORD_DATA ? "word" : "byte");
+	}
+
+	/* export data to kernel code */
+	if (chip.setup)
+		chip.setup(&at24->macc, chip.context);
+
+	return 0;
+
+err_clients:
+	for (i = 1; i < num_addresses; i++)
+		if (at24->client[i])
+			i2c_unregister_device(at24->client[i]);
+
+	return err;
+}
+
+static int at24_remove(struct i2c_client *client)
+{
+	struct at24_data *at24;
+	int i;
+
+	at24 = i2c_get_clientdata(client);
+	sysfs_remove_bin_file(&client->dev.kobj, &at24->bin);
+
+	for (i = 1; i < at24->num_addresses; i++)
+		i2c_unregister_device(at24->client[i]);
+
+	return 0;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static struct i2c_driver at24_driver = {
+	.driver = {
+		.name = "at24",
+		.owner = THIS_MODULE,
+	},
+	.probe = at24_probe,
+	.remove = at24_remove,
+	.id_table = at24_ids,
+};
+
+static int __init at24_init(void)
+{
+	if (!io_limit) {
+		pr_err("at24: io_limit must not be 0!\n");
+		return -EINVAL;
+	}
+
+	io_limit = rounddown_pow_of_two(io_limit);
+	return i2c_add_driver(&at24_driver);
+}
+module_init(at24_init);
+
+static void __exit at24_exit(void)
+{
+	i2c_del_driver(&at24_driver);
+}
+module_exit(at24_exit);
+
+MODULE_DESCRIPTION("Driver for most I2C EEPROMs");
+MODULE_AUTHOR("David Brownell and Wolfram Sang");
+MODULE_LICENSE("GPL");