[U-Boot] [PATCH] Add bootcount to AT91

[Anders Darander]

Hi Tom,

Thanks for your comments.

On Thu, Feb 25, 2010 at 15:24, Tom <Tom.Rix at windriver.com> wrote:
> Anders Darander wrote:
>>
>> From: Anders Darander <ad at datarespons.se>
>> --- a/cpu/arm926ejs/at91/cpu.c
>> +++ b/cpu/arm926ejs/at91/cpu.c
>> @@ -31,6 +31,11 @@
>>  #define AT91_MAIN_CLOCK 0
>>  #endif
>>  +/* The at91sam9260 has 4 GPBR (0-3), we'll use the last one, nr 3,
>> + * to keep track of the bootcount. */
>
> multi-line comments are
> /*
>  *Comment lines
>  */

Correct, I'll fix this.

>> +#define AT91_GPBR_BOOTCOUNT_REGISTER 3
>> +#define AT91_BOOTCOUNT_ADDRESS (AT91_GPBR +
>> 4*AT91_GPBR_BOOTCOUNT_REGISTER)
>> +
>>  int arch_cpu_init(void)
>>  {
>>        return at91_clock_init(AT91_MAIN_CLOCK);
>> @@ -52,3 +57,26 @@ int print_cpuinfo(void)
>>        return 0;
>>  }
>>  #endif
>> +
>> +#ifdef CONFIG_BOOTCOUNT_LIMIT
>> +
>> +void bootcount_store (ulong a)
>> +{
>> +       volatile ulong *save_addr =
>> +               (volatile ulong *)(AT91_BASE_SYS +
>> AT91_BOOTCOUNT_ADDRESS);
>> +
>> +       *save_addr = (BOOTCOUNT_MAGIC & 0xffff0000) | a;
>
> implied length of a is 16 bits.
> the  parameter type passed in should be explicitly cast/masked to u16.

Correct, I'll fix this.

> I see sharing the 32 bits this way is how mpc5xxx does it..
>
> But
>
> mpc8260, mpc83xx, mpc8xx, ppc4xx, ipx store the bootcount_magic and the
> parameter as 2 32bit values.
>
> Is there a memory limitation on why you can not follow what most of the
> others
> are doing ? If there is, please add the explanation as a comment.

Well, I think I'd prefer to keep the boocount and the magic to share a
32-bit register; the main reason being that the AT91SAM9260 only has 4
GPBR, i.e. only four registers that keep it's data between resets.
I'll add a comment about this.

Best regards,
Anders

-- 
Anders Darander
EPO guidelines 1978: "If the contribution to the known art resides
solely in a computer program then the subject matter is not
patentable in whatever manner it may be presented in the claims."