eeprom: at24: split at24_eeprom_read() into specialized functions (9afd6866) · Commits · 戴 / test

drivers/misc/eeprom/at24.c

+71 −54

Original line number	Original line	Diff line number	Diff line
	@@ -165,6 +165,19 @@ MODULE_DEVICE_TABLE(acpi, at24_acpi_ids);
	* This routine supports chips which consume multiple I2C addresses. It		* This routine supports chips which consume multiple I2C addresses. It
	* computes the addressing information to be used for a given r/w request.		* computes the addressing information to be used for a given r/w request.
	* Assumes that sanity checks for offset happened at sysfs-layer.		* Assumes that sanity checks for offset happened at sysfs-layer.
			*
			* 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.
			*
			* 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.
	*/		*/
	static struct i2c_client at24_translate_offset(struct at24_data at24,		static struct i2c_client at24_translate_offset(struct at24_data at24,
	unsigned int *offset)		unsigned int *offset)
	@@ -182,49 +195,57 @@ static struct i2c_client at24_translate_offset(struct at24_data at24,
	return at24->client[i];		return at24->client[i];
	}		}

	static ssize_t at24_eeprom_read(struct at24_data at24, char buf,		static ssize_t at24_eeprom_read_smbus(struct at24_data at24, char buf,
	unsigned int offset, size_t count)		unsigned int offset, size_t count)
	{		{
	struct i2c_msg msg[2];
	u8 msgbuf[2];
	struct i2c_client *client;
	unsigned long timeout, read_time;		unsigned long timeout, read_time;
	int status, i;		struct i2c_client *client;
			int status;
	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);		client = at24_translate_offset(at24, &offset);

	if (count > io_limit)		if (count > io_limit)
	count = io_limit;		count = io_limit;

	if (at24->use_smbus) {
	/* Smaller eeproms can work given some SMBus extension calls */		/* Smaller eeproms can work given some SMBus extension calls */
	if (count > I2C_SMBUS_BLOCK_MAX)		if (count > I2C_SMBUS_BLOCK_MAX)
	count = I2C_SMBUS_BLOCK_MAX;		count = I2C_SMBUS_BLOCK_MAX;
	} else {
			loop_until_timeout(timeout, read_time) {
			status = i2c_smbus_read_i2c_block_data_or_emulated(client,
			offset,
			count, buf);

			dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n",
			count, offset, status, jiffies);

			if (status == count)
			return count;
			}

			return -ETIMEDOUT;
			}

			static ssize_t at24_eeprom_read_i2c(struct at24_data at24, char buf,
			unsigned int offset, size_t count)
			{
			unsigned long timeout, read_time;
			struct i2c_client *client;
			struct i2c_msg msg[2];
			int status, i;
			u8 msgbuf[2];

			memset(msg, 0, sizeof(msg));
			client = at24_translate_offset(at24, &offset);

			if (count > io_limit)
			count = io_limit;

	/*		/*
	* When we have a better choice than SMBus calls, use a		* When we have a better choice than SMBus calls, use a combined I2C
	* combined I2C message. Write address; then read up to		* message. Write address; then read up to io_limit data bytes. Note
	* io_limit data bytes. Note that read page rollover helps us		* that read page rollover helps us here (unlike writes). msgbuf is
	* here (unlike writes). msgbuf is u8 and will cast to our		* u8 and will cast to our needs.
	* needs.
	*/		*/
	i = 0;		i = 0;
	if (at24->chip.flags & AT24_FLAG_ADDR16)		if (at24->chip.flags & AT24_FLAG_ADDR16)
	@@ -239,17 +260,12 @@ static ssize_t at24_eeprom_read(struct at24_data at24, char buf,
	msg[1].flags = I2C_M_RD;		msg[1].flags = I2C_M_RD;
	msg[1].buf = buf;		msg[1].buf = buf;
	msg[1].len = count;		msg[1].len = count;
	}

	loop_until_timeout(timeout, read_time) {		loop_until_timeout(timeout, read_time) {
	if (at24->use_smbus) {
	status = i2c_smbus_read_i2c_block_data_or_emulated(client, offset,
	count, buf);
	} else {
	status = i2c_transfer(client->adapter, msg, 2);		status = i2c_transfer(client->adapter, msg, 2);
	if (status == 2)		if (status == 2)
	status = count;		status = count;
	}
	dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n",		dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n",
	count, offset, status, jiffies);		count, offset, status, jiffies);

	@@ -520,7 +536,8 @@ static int at24_probe(struct i2c_client client, const struct i2c_device_id id)
	at24->chip = chip;		at24->chip = chip;
	at24->num_addresses = num_addresses;		at24->num_addresses = num_addresses;

	at24->read_func = at24_eeprom_read;		at24->read_func = at24->use_smbus ? at24_eeprom_read_smbus
			: at24_eeprom_read_i2c;
	at24->write_func = at24_eeprom_write;		at24->write_func = at24_eeprom_write;

	writable = !(chip.flags & AT24_FLAG_READONLY);		writable = !(chip.flags & AT24_FLAG_READONLY);

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