sh: Fix up large system memory handling for SH7780 PCI.

For systems that have more than 512MB we need to set up an additional
mapping, this fixes up the rounding to the next power of two and splits
out the mapping accordingly between the two local bus mapping windows.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/drivers/pci/pci-sh7780.c

@@ -13,6 +13,7 @@
 #include <linux/pci.h>
 #include <linux/errno.h>
 #include <linux/delay.h>
+#include <linux/log2.h>
 #include "pci-sh4.h"
 #include <asm/mmu.h>
 #include <asm/sizes.h>
@@ -59,7 +60,11 @@ static int __init sh7780_pci_init(void)
 	__raw_writel(SH4_PCICR_PREFIX | SH4_PCICR_PRST,
 		     chan->reg_base + SH4_PCICR);
 
-	/* Wait for it to come back up.. */
+	/*
+	 * Wait for it to come back up. The spec says to allow for up to
+	 * 1 second after toggling the reset pin, but in practice 100ms
+	 * is more than enough.
+	 */
 	mdelay(100);
 
 	id = __raw_readw(chan->reg_base + PCI_VENDOR_ID);
@@ -90,17 +95,34 @@ static int __init sh7780_pci_init(void)
 	 */
 	__raw_writel(SH4_PCICR_PREFIX, chan->reg_base + SH4_PCICR);
 
+	__raw_writel(0, chan->reg_base + PCI_BASE_ADDRESS_0);
+
 	memphys = __pa(memory_start);
-	memsize = memory_end - memory_start;
+	memsize = roundup_pow_of_two(memory_end - memory_start);
 
 	/*
-	 * Set IO and Mem windows to local address
-	 * Make PCI and local address the same for easy 1 to 1 mapping
+	 * If there's more than 512MB of memory, we need to roll over to
+	 * LAR1/LSR1.
 	 */
-	__raw_writel(0, chan->reg_base + PCI_BASE_ADDRESS_0);
+	if (memsize > SZ_512M) {
+		__raw_writel(memphys + SZ_512M, chan->reg_base + SH4_PCILAR1);
+		__raw_writel((((memsize - SZ_512M) - SZ_1M) & 0x1ff00000) | 1,
+			     chan->reg_base + SH4_PCILSR1);
+		memsize = SZ_512M;
+	} else {
+		/*
+		 * Otherwise just zero it out and disable it.
+		 */
+		__raw_writel(0, chan->reg_base + SH4_PCILAR1);
+		__raw_writel(0, chan->reg_base + SH4_PCILSR1);
+	}
 
+	/*
+	 * LAR0/LSR0 covers up to the first 512MB, which is enough to
+	 * cover all of lowmem on most platforms.
+	 */
 	__raw_writel(memphys, chan->reg_base + SH4_PCILAR0);
-	__raw_writel((memsize - 1) << 9 | 1,
+	__raw_writel(((memsize - SZ_1M) & 0x1ff00000) | 1,
 		     chan->reg_base + SH4_PCILSR0);
 
 	/* Clear out PCI arbiter IRQs */