RealView: Add sparsemem support for the RealView PBX platform

The RealView PBX board has two 512MB blocks of memory - one at
0x70000000 (with 256MB mirror at 0) and another at 0x20000000. Only the
block at 0x70000000 (or the mirror at 0) may be used for DMA (e.g.
framebuffer). This patch adds the sparsemem definitions to allow the use
of all the memory split as follows:

  256MB @ 0x00000000 (ZONE_DMA)
  512MB @ 0x20000000 (ZONE_NORMAL)
  256MB @ 0x80000000 (ZONE_NORMAL)
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm/mach-realview/Kconfig

@@ -70,6 +70,8 @@ config MACH_REALVIEW_PBX
 	bool "Support RealView/PBX platform"
 	select ARM_GIC
 	select HAVE_PATA_PLATFORM
+	select ARCH_SPARSEMEM_ENABLE if CPU_V7 && !HIGH_PHYS_OFFSET
+	select ZONE_DMA if SPARSEMEM
 	help
 	  Include support for the ARM(R) RealView PBX platform.
 
@@ -82,6 +84,7 @@ config REALVIEW_HIGH_PHYS_OFFSET
 	  0x70000000, 256MB of which being mirrored at 0x00000000. If
 	  the board supports 512MB of RAM, this option allows the
 	  memory to be accessed contiguously at the high physical
-	  offset.
+	  offset. On the PBX board, disabling this option allows 1GB of
+	  RAM to be used with SPARSEMEM.
 
 endmenu

arch/arm/mach-realview/core.c

@@ -59,6 +59,25 @@
 /* used by entry-macro.S and platsmp.c */
 void __iomem *gic_cpu_base_addr;
 
+#ifdef CONFIG_ZONE_DMA
+/*
+ * Adjust the zones if there are restrictions for DMA access.
+ */
+void __init realview_adjust_zones(int node, unsigned long *size,
+				  unsigned long *hole)
+{
+	unsigned long dma_size = SZ_256M >> PAGE_SHIFT;
+
+	if (!machine_is_realview_pbx() || node || (size[0] <= dma_size))
+		return;
+
+	size[ZONE_NORMAL] = size[0] - dma_size;
+	size[ZONE_DMA] = dma_size;
+	hole[ZONE_NORMAL] = hole[0];
+	hole[ZONE_DMA] = 0;
+}
+#endif
+
 /*
  * This is the RealView sched_clock implementation.  This has
  * a resolution of 41.7ns, and a maximum value of about 179s.
@@ -543,7 +562,7 @@ static int realview_clcd_setup(struct clcd_fb *fb)
 	fb->panel		= realview_clcd_panel();
 
 	fb->fb.screen_base = dma_alloc_writecombine(&fb->dev->dev, framesize,
-						    &dma, GFP_KERNEL);
+						    &dma, GFP_KERNEL | GFP_DMA);
 	if (!fb->fb.screen_base) {
 		printk(KERN_ERR "CLCD: unable to map framebuffer\n");
 		return -ENOMEM;

arch/arm/mach-realview/include/mach/memory.h

@@ -29,4 +29,53 @@
 #define PHYS_OFFSET		UL(0x00000000)
 #endif
 
+#if !defined(__ASSEMBLY__) && defined(CONFIG_ZONE_DMA)
+extern void realview_adjust_zones(int node, unsigned long *size,
+				  unsigned long *hole);
+#define arch_adjust_zones(node, size, hole) \
+	realview_adjust_zones(node, size, hole)
+
+#define ISA_DMA_THRESHOLD	(PHYS_OFFSET + SZ_256M - 1)
+#define MAX_DMA_ADDRESS		(PAGE_OFFSET + SZ_256M)
+#endif
+
+#ifdef CONFIG_SPARSEMEM
+
+/*
+ * Sparsemem definitions for RealView PBX.
+ *
+ * The RealView PBX board has another block of 512MB of RAM at 0x20000000,
+ * however only the block at 0x70000000 (or the 256MB mirror at 0x00000000)
+ * may be used for DMA.
+ *
+ * The macros below define a section size of 256MB and a non-linear virtual to
+ * physical mapping:
+ *
+ * 256MB @ 0x00000000 -> PAGE_OFFSET
+ * 512MB @ 0x20000000 -> PAGE_OFFSET + 0x10000000
+ * 256MB @ 0x80000000 -> PAGE_OFFSET + 0x30000000
+ */
+#ifdef CONFIG_REALVIEW_HIGH_PHYS_OFFSET
+#error "SPARSEMEM not available with REALVIEW_HIGH_PHYS_OFFSET"
+#endif
+
+#define MAX_PHYSMEM_BITS	32
+#define SECTION_SIZE_BITS	28
+
+/* bank page offsets */
+#define PAGE_OFFSET1	(PAGE_OFFSET + 0x10000000)
+#define PAGE_OFFSET2	(PAGE_OFFSET + 0x30000000)
+
+#define __phys_to_virt(phys)						\
+	((phys) >= 0x80000000 ?	(phys) - 0x80000000 + PAGE_OFFSET2 :	\
+	 (phys) >= 0x20000000 ?	(phys) - 0x20000000 + PAGE_OFFSET1 :	\
+	 (phys) + PAGE_OFFSET)
+
+#define __virt_to_phys(virt)						\
+	 ((virt) >= PAGE_OFFSET2 ? (virt) - PAGE_OFFSET2 + 0x80000000 :	\
+	  (virt) >= PAGE_OFFSET1 ? (virt) - PAGE_OFFSET1 + 0x20000000 :	\
+	  (virt) - PAGE_OFFSET)
+
+#endif	/* CONFIG_SPARSEMEM */
+
 #endif

arch/arm/mach-realview/realview_pbx.c

@@ -304,6 +304,26 @@ static struct sys_timer realview_pbx_timer = {
 	.init		= realview_pbx_timer_init,
 };
 
+static void realview_pbx_fixup(struct machine_desc *mdesc, struct tag *tags,
+			       char **from, struct meminfo *meminfo)
+{
+#ifdef CONFIG_SPARSEMEM
+	/*
+	 * Memory configuration with SPARSEMEM enabled on RealView PBX (see
+	 * asm/mach/memory.h for more information).
+	 */
+	meminfo->bank[0].start = 0;
+	meminfo->bank[0].size = SZ_256M;
+	meminfo->bank[1].start = 0x20000000;
+	meminfo->bank[1].size = SZ_512M;
+	meminfo->bank[2].start = 0x80000000;
+	meminfo->bank[2].size = SZ_256M;
+	meminfo->nr_banks = 3;
+#else
+	realview_fixup(mdesc, tags, from, meminfo);
+#endif
+}
+
 static void __init realview_pbx_init(void)
 {
 	int i;
@@ -345,7 +365,7 @@ MACHINE_START(REALVIEW_PBX, "ARM-RealView PBX")
 	.phys_io	= REALVIEW_PBX_UART0_BASE,
 	.io_pg_offst	= (IO_ADDRESS(REALVIEW_PBX_UART0_BASE) >> 18) & 0xfffc,
 	.boot_params	= PHYS_OFFSET + 0x00000100,
-	.fixup		= realview_fixup,
+	.fixup		= realview_pbx_fixup,
 	.map_io		= realview_pbx_map_io,
 	.init_irq	= gic_init_irq,
 	.timer		= &realview_pbx_timer,