rockchip: implement board_lmb_reserve()

Using last bi_dram[...] to initialize "bootm_low" and "bootm_mapsize".
This makes lmb_alloc_base() always alloc from tail of sdram.
If we don't assign it, bi_dram[0] is used by default and it may cause
lmb_alloc_base() fail when bi_dram[0] range is small.

Change-Id: I13c2c2d6135e26e647dcfde4c173d896c800fea5
Signed-off-by: Joseph Chen <chenjh@rock-chips.com>

arch/arm/mach-rockchip/board.c

@@ -275,6 +275,47 @@ void enable_caches(void)
 	dcache_enable();
 }
 
+/*
+ * Using last bi_dram[...] to initialize "bootm_low" and "bootm_mapsize".
+ * This makes lmb_alloc_base() always alloc from tail of sdram.
+ * If we don't assign it, bi_dram[0] is used by default and it may cause
+ * lmb_alloc_base() fail when bi_dram[0] range is small.
+ */
+void board_lmb_reserve(struct lmb *lmb)
+{
+	u64 start, size;
+	char bootm_low[32];
+	char bootm_mapsize[32];
+	int i;
+
+	for (i = 0; i < CONFIG_NR_DRAM_BANKS; i++) {
+		if (!gd->bd->bi_dram[i].size)
+			break;
+	}
+
+	start = gd->bd->bi_dram[i - 1].start;
+	size = gd->bd->bi_dram[i - 1].size;
+
+	/*
+	 * 32-bit kernel: ramdisk/fdt shouldn't be loaded to highmem area, otherwise
+	 * "Unable to handle kernel paging request at virtual address ...".
+	 * If so, using low address region, i.e before tustos region(132MB).
+	 */
+#ifndef ARM64
+	if (start >= ((u64)CONFIG_SYS_SDRAM_BASE + SZ_768M)) {
+		start = gd->bd->bi_dram[i - 2].start;
+		size = gd->bd->bi_dram[i - 2].size;
+	}
+
+	if ((start + size) > ((u64)CONFIG_SYS_SDRAM_BASE + SZ_768M))
+		size = (u64)CONFIG_SYS_SDRAM_BASE + SZ_768M - start;
+#endif
+	sprintf(bootm_low, "0x%llx", start);
+	sprintf(bootm_mapsize, "0x%llx", size);
+	env_set("bootm_low", bootm_low);
+	env_set("bootm_mapsize", bootm_mapsize);
+}
+
 #ifdef CONFIG_ROCKCHIP_PRELOADER_SERIAL
 int board_init_f_init_serial(void)
 {

include/linux/sizes.h

@@ -40,6 +40,7 @@
 #define SZ_128M				0x08000000
 #define SZ_256M				0x10000000
 #define SZ_512M				0x20000000
+#define SZ_768M				0x30000000
 
 #define SZ_1G				0x40000000
 #define SZ_2G				0x80000000