add EEPROM usage instructions and example for kernel side. dm644x-evm was taken as example.
Signed-off-by: Yegor Yefremov <[email protected]> --- Documentation/misc-devices/eeprom | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) Index: b/Documentation/misc-devices/eeprom =================================================================== --- a/Documentation/misc-devices/eeprom +++ b/Documentation/misc-devices/eeprom @@ -90,7 +90,41 @@ Use: +1. Userland + After inserting the module (and any other required SMBus/i2c modules), you should have some EEPROM directories in /sys/bus/i2c/devices/* of names such as "0-0050". Inside each of these is a series of files, the eeprom file contains the binary data from EEPROM. + +2. Kernel + +It is also possible to read/write EEPROM from kernel side. at24.c provides two +routines at24_macc_read() and at24_macc_write(). Those routines can be used +as part of setup() routine, when configuring platform data for i2c EEPROM. + +Example: + +arch/arm/mach-davinci/board-dm644x-evm.c uses EEPROM to store MAC address. +This is how EEPROM platform data will be set up: + +static struct at24_platform_data eeprom_info = { + .byte_len = (256*1024) / 8, + .page_size = 64, + .flags = AT24_FLAG_ADDR16, + .setup = davinci_get_mac_addr, + .context = (void *)0x7f00, +}; + +davinci_get_mac_addr() will be called from at24_probe() and fetches the MAC +address from specified offset: + +void davinci_get_mac_addr(struct memory_accessor *mem_acc, void *context) +{ + char *mac_addr = davinci_soc_info.emac_pdata->mac_addr; + off_t offset = (off_t)context; + + /* Read MAC addr from EEPROM */ + if (mem_acc->read(mem_acc, mac_addr, offset, ETH_ALEN) == ETH_ALEN) + pr_info("Read MAC addr from EEPROM: %pM\n", mac_addr); +} -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
