u-boot has a standard "serial#" environment variable that is suitable for storing the iSerial number we will supply via the USB device descriptor. serial# is automatically picked up by the disk subsystem in u-boot - thus providing a handy unique identifier in /dev/disk/by-id as detailed below.
Storing the hardware serial identifier in serial# means we can change the serial# if we want before USB enumeration - thus making iSerial automatic via OTP but overridable if necessary.
This patch reads the defined OTP fuse and sets environment variable "serial#" to the value read. If there is any error in reading the value the boot will continue and "serial#" will be set to zero.
With this patch in place the USB mass storage device will appear in /dev/disk/by-id with a unique name based on the OTP value. For example
/dev/disk/by-id/usb-Linux_UMS_disk_0_WaRP7-0xf42400d3000000d4-0:0
Signed-off-by: Bryan O'Donoghue bryan.odonoghue@linaro.org Cc: Fabio Estevam fabio.estevam@nxp.com Reviewed-by: Rui Miguel Silva rui.silva@linaro.org Reviewed-by: Ryan Harkin ryan.harkin@linaro.org --- board/warp7/warp7.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/board/warp7/warp7.c b/board/warp7/warp7.c index 2cec448..a27993f 100644 --- a/board/warp7/warp7.c +++ b/board/warp7/warp7.c @@ -239,6 +239,9 @@ int board_usb_phy_mode(int port) int board_late_init(void) { struct wdog_regs *wdog = (struct wdog_regs *)WDOG1_BASE_ADDR; + u64 serial_id = 0; + char serial_string[0x20]; + int ret;
imx_iomux_v3_setup_multiple_pads(wdog_pads, ARRAY_SIZE(wdog_pads));
@@ -250,5 +253,14 @@ int board_late_init(void) */ clrsetbits_le16(&wdog->wcr, 0, 0x10);
+ /* Set serial# standard environment variable based on OTP settings */ + ret = warp7_get_serialid(&serial_id); + if (ret) + printf("error %d reading from serial# OTP fuse\n", ret); + + snprintf(serial_string, sizeof(serial_string), "WaRP7-0x%016llx", + serial_id); + env_set("serial#", serial_string); + return 0; }