[U-Boot-Users] [PATCH] lite5200b: support wake from low-power mode

[Domen Puncer]

Puts SDRAM out of self-refresh and transfers control to
address saved at physical 0x0.

Used by Linux patches posted at
http://ozlabs.org/pipermail/linuxppc-embedded/2007-March/026242.html

Index: u-boot-of.git/board/icecube/icecube.c
===================================================================
--- u-boot-of.git.orig/board/icecube/icecube.c
+++ u-boot-of.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 = 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;
 }
 
Index: u-boot-of.git/include/mpc5xxx.h
===================================================================
--- u-boot-of.git.orig/include/mpc5xxx.h
+++ u-boot-of.git/include/mpc5xxx.h
@@ -189,6 +189,7 @@
 #define MPC5XXX_WU_GPIO_ODE     (MPC5XXX_WU_GPIO + 0x0004)
 #define MPC5XXX_WU_GPIO_DIR     (MPC5XXX_WU_GPIO + 0x0008)
 #define MPC5XXX_WU_GPIO_DATA    (MPC5XXX_WU_GPIO + 0x000c)
+#define MPC5XXX_WU_GPIO_DATA_I  (MPC5XXX_WU_GPIO + 0x0020)
 
 /* PCI registers */
 #define MPC5XXX_PCI_CMD		(MPC5XXX_PCI + 0x04)

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