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author | Bartosz Golaszewski <bgolaszewski@baylibre.com> | 2016-06-06 10:48:51 +0200 |
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committer | Wolfram Sang <wsa@the-dreams.de> | 2016-07-17 19:57:30 +0200 |
commit | 818d0220d857cc92cb37600758c5b47c3df3782b (patch) | |
tree | dea3c7a564d3ee9c181d1f867414965a7d29025c /drivers/misc/eeprom | |
parent | a7284a82e826b88eb6264747cee57888d4076c48 (diff) | |
download | linux-818d0220d857cc92cb37600758c5b47c3df3782b.tar.gz linux-818d0220d857cc92cb37600758c5b47c3df3782b.tar.bz2 linux-818d0220d857cc92cb37600758c5b47c3df3782b.zip |
eeprom: at24: support reading the serial number for 24csxx
The chips from the at24cs family have two memory areas - a regular
read-write block and a read-only area containing the serial number.
The latter is visible on a different slave address (the address of the
rw memory block + 0x08). In order to access both blocks the user needs
to instantiate a regular at24c device for the rw block address and a
corresponding at24cs device on the serial number block address.
Add a function that allows to access the serial number and assign it
to at24->read_func if the chip allows serial number read operations
and the driver was passed the relevant flag for this device.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/misc/eeprom')
-rw-r--r-- | drivers/misc/eeprom/at24.c | 80 |
1 files changed, 78 insertions, 2 deletions
diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c index 6acf35af271c..3b27ff14876c 100644 --- a/drivers/misc/eeprom/at24.c +++ b/drivers/misc/eeprom/at24.c @@ -134,16 +134,34 @@ static const struct i2c_device_id at24_ids[] = { { "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) }, + { "24cs01", AT24_DEVICE_MAGIC(16, + AT24_FLAG_SERIAL | AT24_FLAG_READONLY) }, { "24c02", AT24_DEVICE_MAGIC(2048 / 8, 0) }, + { "24cs02", AT24_DEVICE_MAGIC(16, + AT24_FLAG_SERIAL | AT24_FLAG_READONLY) }, /* 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) }, + { "24cs04", AT24_DEVICE_MAGIC(16, + AT24_FLAG_SERIAL | AT24_FLAG_READONLY) }, /* 24rf08 quirk is handled at i2c-core */ { "24c08", AT24_DEVICE_MAGIC(8192 / 8, 0) }, + { "24cs08", AT24_DEVICE_MAGIC(16, + AT24_FLAG_SERIAL | AT24_FLAG_READONLY) }, { "24c16", AT24_DEVICE_MAGIC(16384 / 8, 0) }, + { "24cs16", AT24_DEVICE_MAGIC(16, + AT24_FLAG_SERIAL | AT24_FLAG_READONLY) }, { "24c32", AT24_DEVICE_MAGIC(32768 / 8, AT24_FLAG_ADDR16) }, + { "24cs32", AT24_DEVICE_MAGIC(16, + AT24_FLAG_ADDR16 | + AT24_FLAG_SERIAL | + AT24_FLAG_READONLY) }, { "24c64", AT24_DEVICE_MAGIC(65536 / 8, AT24_FLAG_ADDR16) }, + { "24cs64", AT24_DEVICE_MAGIC(16, + AT24_FLAG_ADDR16 | + AT24_FLAG_SERIAL | + AT24_FLAG_READONLY) }, { "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) }, @@ -276,6 +294,59 @@ static ssize_t at24_eeprom_read_i2c(struct at24_data *at24, char *buf, return -ETIMEDOUT; } +static ssize_t at24_eeprom_read_serial(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]; + u8 addrbuf[2]; + int status; + + client = at24_translate_offset(at24, &offset); + + memset(msg, 0, sizeof(msg)); + msg[0].addr = client->addr; + msg[0].buf = addrbuf; + + /* + * The address pointer of the device is shared between the regular + * EEPROM array and the serial number block. The dummy write (part of + * the sequential read protocol) ensures the address pointer is reset + * to the desired position. + */ + if (at24->chip.flags & AT24_FLAG_ADDR16) { + /* + * For 16 bit address pointers, the word address must contain + * a '10' sequence in bits 11 and 10 regardless of the + * intended position of the address pointer. + */ + addrbuf[0] = 0x08; + addrbuf[1] = offset; + msg[0].len = 2; + } else { + /* + * Otherwise the word address must begin with a '10' sequence, + * regardless of the intended address. + */ + addrbuf[0] = 0x80 + offset; + msg[0].len = 1; + } + + msg[1].addr = client->addr; + msg[1].flags = I2C_M_RD; + msg[1].buf = buf; + msg[1].len = count; + + loop_until_timeout(timeout, read_time) { + status = i2c_transfer(client->adapter, msg, 2); + if (status == 2) + return count; + } + + return -ETIMEDOUT; +} + /* * Note that if the hardware write-protect pin is pulled high, the whole * chip is normally write protected. But there are plenty of product @@ -577,8 +648,13 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id) at24->chip = chip; at24->num_addresses = num_addresses; - at24->read_func = at24->use_smbus ? at24_eeprom_read_smbus - : at24_eeprom_read_i2c; + if (chip.flags & AT24_FLAG_SERIAL) { + at24->read_func = at24_eeprom_read_serial; + } else { + at24->read_func = at24->use_smbus ? at24_eeprom_read_smbus + : at24_eeprom_read_i2c; + } + if (at24->use_smbus) { if (at24->use_smbus_write == I2C_SMBUS_I2C_BLOCK_DATA) at24->write_func = at24_eeprom_write_smbus_block; |