On 08/10/2010 06:39 AM, Sekhar Nori wrote:
> The TI DA850/OMAP-L138/AM18x EVM can be populated with devices
> of different speed grades.
>
> The maximum speed the chip can support can only be determined from
> the label on the package (not software readable).
>
> Introduce a method to pass the speed grade information to kernel
> using ATAG_REVISION. The kernel uses this information to determine
> the maximum speed reachable using cpufreq.
>
> Note that U-Boot itself does not set the CPU rate. The CPU
> speed is setup by a primary bootloader ("UBL"). The rate setup
> by UBL could be different from the maximum speed grade of the
> device.
>
> Signed-off-by: Sekhar Nori<nsek...@ti.com>
> ---
> Applies to latest of U-Boot mainline master
>
> board/davinci/da8xxevm/da850evm.c | 38
> +++++++++++++++++++++++++++++++++++++
> include/configs/da850evm.h | 1 +
> 2 files changed, 39 insertions(+), 0 deletions(-)
>
> diff --git a/board/davinci/da8xxevm/da850evm.c
> b/board/davinci/da8xxevm/da850evm.c
> index 959b2c6..6a6d4fb 100644
> --- a/board/davinci/da8xxevm/da850evm.c
> +++ b/board/davinci/da8xxevm/da850evm.c
> @@ -70,6 +70,44 @@ static const struct lpsc_resource lpsc[] = {
> { DAVINCI_LPSC_GPIO },
> };
>
> +#ifndef CONFIG_DA850_EVM_MAX_SPEED
> +#define CONFIG_DA850_EVM_MAX_SPEED 300000
> +#endif
> +
> +/*
> + * get_board_rev() - setup to pass kernel board revision information
> + * Returns:
> + * bit[0-3] Maximum speed supported by the DA850/OMAP-L138/AM18x part
> + * 0 - 300 MHz
> + * 1 - 372 MHz
> + * 2 - 408 MHz
> + * 3 - 456 MHz
> + */
> +u32 get_board_rev(void)
> +{
> + char *s;
> + u32 maxspeed = CONFIG_DA850_EVM_MAX_SPEED;
> + u32 rev = 0;
> +
> + s = getenv("maxspeed");
> + if (s)
> + maxspeed = simple_strtoul(s, NULL, 10);
> +
> + switch (maxspeed) {
> + case 456000:
> + rev |= 3;
> + break;
> + case 408000:
> + rev |= 2;
> + break;
> + case 372000:
> + rev |= 1;
wondering if the |= makes any sense...
> + break;
> + }
> +
> + return rev;
IMHO, the logic could be simplified?
option 1:
u8 rev=0;
s = simple_strtoul(s, NULL, 10);
if (s) {
switch (simple_strtoul(s, NULL, 10)) {
case 456000:
rev = 3;
break;
case 408000:
rev = 2;
break;
case 372000:
rev = 1;
break;
}
}
option 2:
if you think that the speeds could get added in the future, that switch
is going to look pretty ugly.. use a lookup instead..
u32 speeds[]={372000,408000,456000};
int i;
u32 mspeed;
s=simple_strtoul(s, NULL, 10);
maxspeed = simple_strtoul(s, NULL, 10);
for (i=0;i<ARRAY_SIZE(speeds);i++)
if (maxspeed == speeds[i])
return i + 1;
return 0;
> +}
> +
> int board_init(void)
> {
> #ifndef CONFIG_USE_IRQ
> diff --git a/include/configs/da850evm.h b/include/configs/da850evm.h
> index 357715d..3ea9032 100644
> --- a/include/configs/da850evm.h
> +++ b/include/configs/da850evm.h
> @@ -102,6 +102,7 @@
> */
> #define LINUX_BOOT_PARAM_ADDR (CONFIG_SYS_MEMTEST_START + 0x100)
> #define CONFIG_CMDLINE_TAG
> +#define CONFIG_REVISION_TAG
> #define CONFIG_SETUP_MEMORY_TAGS
> #define CONFIG_BOOTARGS \
> "mem=32M console=ttyS2,115200n8 root=/dev/mtdblock2 rw noinitrd ip=dhcp"
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