[PATCH] ARM: mx6: Add function to read UNIQUE_ID

[Heinrich Schuchardt]

On 2/4/21 9:52 PM, Sean Anderson wrote:
>
>
> On 2/4/21 3:41 PM, Tom Rini wrote:
>  > On Thu, Feb 04, 2021 at 03:29:48PM -0500, Sean Anderson wrote:
>  >
>  >> This is almost identical to the imx7 version, except that the register
>  >> names are different.
>  >>
>  >> Signed-off-by: Sean Anderson <sean.anderson at seco.com>
>  >> ---
>  >>
>  >>   arch/arm/mach-imx/mx6/soc.c | 33 +++++++++++++++++++++++++++++++++
>  >>   1 file changed, 33 insertions(+)
>  >>
>  >> diff --git a/arch/arm/mach-imx/mx6/soc.c b/arch/arm/mach-imx/mx6/soc.c
>  >> index bf6dddfdc9..cb729be46f 100644
>  >> --- a/arch/arm/mach-imx/mx6/soc.c
>  >> +++ b/arch/arm/mach-imx/mx6/soc.c
>  >> @@ -11,6 +11,7 @@
>  >>   #include <linux/delay.h>
>  >>   #include <linux/errno.h>
>  >>   #include <asm/io.h>
>  >> +#include <asm/setup.h>
>  >>   #include <asm/arch/imx-regs.h>
>  >>   #include <asm/arch/clock.h>
>  >>   #include <asm/arch/sys_proto.h>
>  >> @@ -705,6 +706,38 @@ int arch_misc_init(void)
>  >>   }
>  >>   #endif
>  >>
>  >> +#ifdef CONFIG_SERIAL_TAG
>  >> +/*
>  >> + * UNIQUE_ID describes a unique ID based on silicon wafer
>  >> + * and die X/Y position
>  >> + *
>  >> + * UNIQUE_ID offset 0x410
>  >> + * 31:0 fuse 0
>  >> + * FSL-wide unique, encoded LOT ID STD II/SJC CHALLENGE/ Unique ID
>  >> + *
>  >> + * UNIQUE_ID offset 0x420
>  >> + * 31:24 fuse 1
>  >> + * The X-coordinate of the die location on the wafer/SJC CHALLENGE/
> Unique ID
>  >> + * 23:16 fuse 1
>  >> + * The Y-coordinate of the die location on the wafer/SJC CHALLENGE/
> Unique ID
>  >> + * 15:11 fuse 1
>  >> + * The wafer number of the wafer on which the device was
> fabricated/SJC
>  >> + * CHALLENGE/ Unique ID
>  >> + * 10:0 fuse 1
>  >> + * FSL-wide unique, encoded LOT ID STD II/SJC CHALLENGE/ Unique ID
>  >> + */
>  >> +void get_board_serial(struct tag_serialnr *serialnr)
>  >> +{
>  >> +    struct ocotp_regs *ocotp = (struct ocotp_regs *)OCOTP_BASE_ADDR;
>  >> +    struct fuse_bank *bank = &ocotp->bank[0];
>  >> +    struct fuse_bank0_regs *fuse =
>  >> +        (struct fuse_bank0_regs *)bank->fuse_regs;
>  >> +
>  >> +    serialnr->low = fuse->uid_low;
>  >> +    serialnr->high = fuse->uid_high;
>  >> +}
>  >> +#endif
>  >> +
>  >>   /*
>  >>    * gpr_init() function is common for boards using MX6S, MX6DL, MX6D,
>  >>    * MX6Q and MX6QP processors
>  >
>  > NAK.  This needs to use the normal mechanism to populate "serial#"
>  > directly and not abuse the old ATAG infrastructure.
>
> What is the "normal" mechanism? Define something like
> omap_die_id_serial which sets serial# directly? From what I can tell,
> get_board_serial is the "generic" function for separating the getting of
> the serial from the setting of serial#.
>
> --Sean

get_board_serial() is defined as empty function in bootm.h if
CONFIG_SERIAL_TAG=n. But CONFIG_SERIAL_TAG is not documented anywhere.

board/gateworks/gw_ventana/gw_ventana.c has this comment:

#ifdef CONFIG_SERIAL_TAG
/*
  * called when setting up ATAGS before booting kernel
  * populate serialnum from the following (in order of priority):
  *   serial# env var
  *   eeprom
  */
void get_board_serial(struct tag_serialnr *serialnr)

serial# seems to be set generally in misc_init_r().
But doing this on a per board level seems to be an inadequate design for
i.mx6. The best place for i.mx6 seems to be arch_misc_init().

@Tom:
Linux Kconfig has:

CONFIG_ATAGS:
  This is the traditional way of passing data to the kernel at boot time.
  If you are solely relying on the flattened device tree (or
  the ARM_ATAG_DTB_COMPAT option) then you may unselect this option
  to remove ATAGS support from your kernel binary.  If unsure, leave this
  to y.

CONFIG_DEPRECATED_PARAM_STRUCT
  depends on ATAGS
  This was deprecated in 2001 and announced to live on for 5 years.
  Some old boot loaders still use this way.

As this has been deprecated 20 years ago, why don't we remove it from
U-Boot?

Best regards

Heinrich