p1022ds: fix switching of DIU/LBC signals

On the P1022, the pins which drive the video display (DIU) are muxed with the
local bus controller (LBC), so if the DIU is active, the pins need to be
temporarily muxed to LBC whenever accessing NOR flash.

The code which handled this transition is checking and changing the wrong
bits in PMUXCR.

Also add a follow-up read after a write to NOR flash if we're going to
mux back to DIU after the write, as described in the P1022 RM.

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

board/freescale/p1022ds/diu.c

@@ -32,6 +32,7 @@
 
 #define PMUXCR_ELBCDIU_MASK	0xc0000000
 #define PMUXCR_ELBCDIU_NOR16	0x80000000
+#define PMUXCR_ELBCDIU_DIU	0x40000000
 
 /*
  * DIU Area Descriptor
@@ -131,9 +132,8 @@ int platform_diu_init(unsigned int *xres, unsigned int *yres)
 	px_brdcfg0 = in_8(lbc_lcs1_ba);
 	out_8(lbc_lcs1_ba, px_brdcfg0 | PX_BRDCFG0_ELBC_DIU);
 
-	/* Setting PMUXCR to switch to DVI from ELBC */
-	clrsetbits_be32(&gur->pmuxcr,
-		PMUXCR_ELBCDIU_MASK, PMUXCR_ELBCDIU_NOR16);
+	/* Set PMUXCR to switch the muxed pins from the LBC to the DIU */
+	clrsetbits_be32(&gur->pmuxcr, PMUXCR_ELBCDIU_MASK, PMUXCR_ELBCDIU_DIU);
 	pmuxcr = in_be32(&gur->pmuxcr);
 
 	return fsl_diu_init(*xres, pixel_format, 0);
@@ -161,7 +161,7 @@ static int set_mux_to_lbc(void)
 	ccsr_gur_t *gur = (void *)CONFIG_SYS_MPC85xx_GUTS_ADDR;
 
 	/* Switch the muxes only if they're currently set to DIU mode */
-	if ((in_be32(&gur->pmuxcr) & PMUXCR_ELBCDIU_MASK) ==
+	if ((in_be32(&gur->pmuxcr) & PMUXCR_ELBCDIU_MASK) !=
 	    PMUXCR_ELBCDIU_NOR16) {
 		/*
 		 * In DIU mode, the PIXIS can only be accessed indirectly
@@ -216,8 +216,17 @@ void flash_write8(u8 value, void *addr)
 	int sw = set_mux_to_lbc();
 
 	__raw_writeb(value, addr);
-	if (sw)
+	if (sw) {
+		/*
+		 * To ensure the post-write is completed to eLBC, software must
+		 * perform a dummy read from one valid address from eLBC space
+		 * before changing the eLBC_DIU from NOR mode to DIU mode.
+		 * set_mux_to_diu() includes a sync that will ensure the
+		 * __raw_readb() completes before it switches the mux.
+		 */
+		__raw_readb(addr);
 		set_mux_to_diu();
+	}
 }
 
 void flash_write16(u16 value, void *addr)
@@ -225,8 +234,17 @@ void flash_write16(u16 value, void *addr)
 	int sw = set_mux_to_lbc();
 
 	__raw_writew(value, addr);
-	if (sw)
+	if (sw) {
+		/*
+		 * To ensure the post-write is completed to eLBC, software must
+		 * perform a dummy read from one valid address from eLBC space
+		 * before changing the eLBC_DIU from NOR mode to DIU mode.
+		 * set_mux_to_diu() includes a sync that will ensure the
+		 * __raw_readb() completes before it switches the mux.
+		 */
+		__raw_readb(addr);
 		set_mux_to_diu();
+	}
 }
 
 void flash_write32(u32 value, void *addr)
@@ -234,18 +252,47 @@ void flash_write32(u32 value, void *addr)
 	int sw = set_mux_to_lbc();
 
 	__raw_writel(value, addr);
-	if (sw)
+	if (sw) {
+		/*
+		 * To ensure the post-write is completed to eLBC, software must
+		 * perform a dummy read from one valid address from eLBC space
+		 * before changing the eLBC_DIU from NOR mode to DIU mode.
+		 * set_mux_to_diu() includes a sync that will ensure the
+		 * __raw_readb() completes before it switches the mux.
+		 */
+		__raw_readb(addr);
 		set_mux_to_diu();
+	}
 }
 
 void flash_write64(u64 value, void *addr)
 {
 	int sw = set_mux_to_lbc();
+	uint32_t *p = addr;
 
-	/* There is no __raw_writeq(), so do the write manually */
-	*(volatile u64 *)addr = value;
-	if (sw)
+	/*
+	 * There is no __raw_writeq(), so do the write manually.  We don't trust
+	 * the compiler, so we use inline assembly.
+	 */
+	__asm__ __volatile__(
+		"stw%U0%X0 %2,%0;\n"
+		"stw%U1%X1 %3,%1;\n"
+		: "=m" (*p), "=m" (*(p + 1))
+		: "r" ((uint32_t) (value >> 32)), "r" ((uint32_t) (value)));
+
+	if (sw) {
+		/*
+		 * To ensure the post-write is completed to eLBC, software must
+		 * perform a dummy read from one valid address from eLBC space
+		 * before changing the eLBC_DIU from NOR mode to DIU mode.  We
+		 * read addr+4 because we just wrote to addr+4, so that's how we
+		 * maintain execution order.  set_mux_to_diu() includes a sync
+		 * that will ensure the __raw_readb() completes before it
+		 * switches the mux.
+		 */
+		__raw_readb(addr + 4);
 		set_mux_to_diu();
+	}
 }
 
 u8 flash_read8(void *addr)