Subject: Re: [PATCH] icecube/lite5200b: wakeup from low-power support

From: Domen Puncer <[email-masked]>
Date: Tue, 3 Apr 2007 10:46:49 +0200

U-Boot part of Lite5200b low power mode support.
Puts SDRAM out of self-refresh and transfers control to
address saved at physical 0x0.

---
On 26/03/07 10:08 -0600, Grant Likely wrote:
> On 3/15/07, Domen Puncer <[email-masked]> 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 <[email-masked]>
> 

OK. This one should be better:

 Makefile                |    5 ++++
 board/icecube/icecube.c |   49 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 54 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 +42,53 @@
 #include "mt48lc16m16a2-75.h"
 # endif
 #endif
+
+#ifdef CONFIG_LITE5200B_PM
+/* 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 +255,8 @@ long int initdram (int board_type)
 		__asm__ volatile ("sync");
 	}
 
+	lite5200b_wakeup();
+
 	return dramsize + dramsize2;
 }
 
Index: u-boot.git/Makefile
===================================================================
--- u-boot.git.orig/Makefile
+++ u-boot.git/Makefile
@@ -430,6 +430,7 @@ inka4x0_config:	unconfig
 	@$(MKCONFIG) inka4x0 ppc mpc5xxx inka4x0
 
 lite5200b_config	\
+lite5200b_PM_config	\
 lite5200b_LOWBOOT_config:	unconfig
 	@mkdir -p $(obj)include
 	@mkdir -p $(obj)board/icecube
@@ -438,6 +439,10 @@ lite5200b_LOWBOOT_config:	unconfig
 	@ echo "... DDR memory revision"
 	@ echo "#define CONFIG_MPC5200"		>>$(obj)include/config.h
 	@ echo "#define CONFIG_LITE5200B"	>>$(obj)include/config.h
+	@[ -z "$(findstring _PM_,$@)" ] || \
+		{ echo "#define CONFIG_LITE5200B_PM"	>>$(obj)include/config.h ; \
+		  echo "... with power management (low-power mode) support" ; \
+		}
 	@[ -z "$(findstring LOWBOOT_,$@)" ] || \
 		{ echo "TEXT_BASE = 0xFF000000" >$(obj)board/icecube/config.tmp ; \
 		  echo "... with LOWBOOT configuration" ; \