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

[Sean Anderson]

On 2/4/21 4:04 PM, Tom Rini wrote:
 > On Thu, Feb 04, 2021 at 03:52:51PM -0500, 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#.
 >
 > The normal method is more like stm32 (arch/arm/mach-stm32mp/cpu.c) or
 > rockchip (arch/arm/mach-rockchip/misc.c) where there's no ATAGs legacy
 > design (which is where omap_die_id_serial is).
 >

Thanks for the reference. It's often difficult to figure out what the
"best practice" is with so many boards added at different times.

--Sean