[U-Boot-Users] [PATCH] icecube/lite5200b: wakeup from low-power support

[Grant Likely]

On 3/15/07, Domen Puncer <domen.puncer at telargo.com> wrote:
> U-Boot part of Lite5200b low power mode support.
> Puts SDRAM out of self-refresh and transfers control to
> address saved at physical 0x0.

This looks pretty straight forward.

My only comment is that psc2_4 is probably used as GPIO instead of
power control by some users (The lite5200 is an eval board after all).
 Maybe wrap the code with #ifdef CONFIG_LITE5200B_PM (instead of
CONFIG_LITE5200B) so that it can be easily compiled out.

Also, '//' style comments should be changed to '/* */'

Otherwise;
Acked-by: Grant Likely <grant.likely at secretlab.ca>

g.

>
> ---
>  board/icecube/icecube.c |   50 ++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 50 insertions(+)
>
> Index: u-boot.git/board/icecube/icecube.c
> ===================================================================
> --- u-boot.git.orig/board/icecube/icecube.c
> +++ u-boot.git/board/icecube/icecube.c
> @@ -42,6 +42,54 @@
>  #include "mt48lc16m16a2-75.h"
>  # endif
>  #endif
> +
> +#ifdef CONFIG_LITE5200B
> +/* u-boot part of low-power mode implementation */
> +#define SAVED_ADDR (*(void **)0x00000000)
> +#define PSC2_4 0x02
> +
> +void lite5200b_wakeup(void)
> +{
> +       unsigned char wakeup_pin;
> +       void (*linux_wakeup)(void);
> +
> +       /* check PSC2_4, if it's down "QT" is signaling we have a wakeup
> +        * from low power mode */
> +       *(vu_char *)MPC5XXX_WU_GPIO_ENABLE = PSC2_4;
> +       __asm__ volatile ("sync");
> +
> +       wakeup_pin = *(vu_char *)MPC5XXX_WU_GPIO_DATA_I;
> +       if (wakeup_pin & PSC2_4)
> +               return;
> +
> +       /* acknowledge to "QT"
> +        * by holding pin at 1 for 10 uS */
> +       *(vu_char *)MPC5XXX_WU_GPIO_DIR = PSC2_4;
> +       __asm__ volatile ("sync");
> +       *(vu_char *)MPC5XXX_WU_GPIO_DATA_O = PSC2_4;
> +       __asm__ volatile ("sync");
> +       udelay(10);
> +
> +       /* put ram out of self-refresh */
> +       *(vu_long *)MPC5XXX_SDRAM_CTRL |= 0x80000000;   // mode_en
> +       __asm__ volatile ("sync");
> +       *(vu_long *)MPC5XXX_SDRAM_CTRL |= 0x50000000;   // cke ref_en
> +       __asm__ volatile ("sync");
> +       *(vu_long *)MPC5XXX_SDRAM_CTRL &= ~0x80000000;  // !mode_en
> +       __asm__ volatile ("sync");
> +       udelay(10); /* wait a bit */
> +
> +       /* jump back to linux kernel code */
> +       linux_wakeup = SAVED_ADDR;
> +       printf("\n\nLooks like we just woke, transferring control to 0x%08lx\n",
> +                       linux_wakeup);
> +       linux_wakeup();
> +}
> +#else
> +#define lite5200b_wakeup()
> +#endif
> +
> +
>  #ifndef CFG_RAMBOOT
>  static void sdram_start (int hi_addr)
>  {
> @@ -208,6 +256,8 @@ long int initdram (int board_type)
>                 __asm__ volatile ("sync");
>         }
>
> +       lite5200b_wakeup();
> +
>         return dramsize + dramsize2;
>  }