[RFC 2/2] rockchip: rk3588: Add SoC specific RAM bank logic

[Chris Morgan]

From: Chris Morgan <macromorgan at hotmail.com>

Add SoC specific RAM bank logic for the rk3588 boards. This logic
works by reading the ATAGS created by the ROCKCHIP_TPL stage and
applies fixups on those to ensure we aren't stepping on any
reserved memory addresses.

The existing logic requires us to define memory holes to allow
devices with 16GB or more RAM to function properly, as well as
blocking up to 256MB of otherwise accessible RAM.

Signed-off-by: Chris Morgan <macromorgan at hotmail.com>
---
 arch/arm/mach-rockchip/rk3588/rk3588.c | 93 ++++++++++++++++++++++++++
 1 file changed, 93 insertions(+)

diff --git a/arch/arm/mach-rockchip/rk3588/rk3588.c b/arch/arm/mach-rockchip/rk3588/rk3588.c
index 38e95a6e2b..73ff742ffc 100644
--- a/arch/arm/mach-rockchip/rk3588/rk3588.c
+++ b/arch/arm/mach-rockchip/rk3588/rk3588.c
@@ -7,10 +7,14 @@
 #include <common.h>
 #include <spl.h>
 #include <asm/armv8/mmu.h>
+#include <asm/global_data.h>
 #include <asm/io.h>
 #include <asm/arch-rockchip/bootrom.h>
 #include <asm/arch-rockchip/hardware.h>
 #include <asm/arch-rockchip/ioc_rk3588.h>
+#include <linux/errno.h>
+
+DECLARE_GLOBAL_DATA_PTR;
 
 #define FIREWALL_DDR_BASE		0xfe030000
 #define FW_DDR_MST5_REG			0x54
@@ -35,6 +39,15 @@
 #define BUS_IOC_GPIO2D_IOMUX_SEL_H	0x5c
 #define BUS_IOC_GPIO3A_IOMUX_SEL_L	0x60
 
+/* Tag magic */
+#define ATAG_CORE_MAGIC		0x54410001
+#define ATAG_DDR_MEM_MAGIC	0x54410052
+
+/* Tag size and offset */
+#define ATAGS_SIZE		(0x2000) /* 8K */
+#define ATAGS_OFFSET		(SZ_2M - ATAGS_SIZE)
+#define ATAGS_PHYS_BASE		(CFG_SYS_SDRAM_BASE + ATAGS_OFFSET)
+
 /**
  * Boot-device identifiers used by the BROM on RK3588 when device is booted
  * from SPI flash. IOMUX used for SPI flash affect the value used by the BROM
@@ -83,6 +96,16 @@ static struct mm_region rk3588_mem_map[] = {
 
 struct mm_region *mem_map = rk3588_mem_map;
 
+/* ATAGS memory structure. */
+struct tag_ddr_mem {
+	u32 count;
+	u32 version;
+	u64 bank[20];
+	u32 flags;
+	u32 data[2];
+	u32 hash;
+} __packed;
+
 /* GPIO0B_IOMUX_SEL_H */
 enum {
 	GPIO0B5_SHIFT		= 4,
@@ -130,6 +153,76 @@ void rockchip_stimer_init(void)
 }
 #endif
 
+/**
+ * rk_get_ram_banks() - Get RAM banks from Rockchip TPL stage
+ *
+ * Iterate through the defined ATAGS memory location to first find a
+ * valid core header, then find a valid ddr_info header. Sanity check
+ * the number of banks found. Then, iterate through the data to add
+ * each individual memory bank. Perform fixups on memory banks that
+ * overlap with a reserved space. If an error condition is received,
+ * it is expected that memory bank setup will fall back on existing
+ * logic. If CONFIG_IS_ENABLED(ROCKCHIP_EXTERNAL_TPL) is false then
+ * immediately return.
+ *
+ * Return 0 on success or negative on error.
+ */
+int rk_get_ram_banks(void)
+{
+	struct tag_ddr_mem *ddr_info;
+	size_t val;
+	size_t addr = ATAGS_PHYS_BASE;
+
+	if (!IS_ENABLED(CONFIG_ROCKCHIP_EXTERNAL_TPL))
+		return -EPERM;
+
+	while (addr < (ATAGS_PHYS_BASE + ATAGS_SIZE)) {
+		val = readl(addr);
+		if (val == ATAG_CORE_MAGIC)
+			break;
+		addr += 4;
+	}
+	if (addr >= (ATAGS_PHYS_BASE + ATAGS_SIZE))
+		return -ENODATA;
+
+	while (addr < (ATAGS_PHYS_BASE + ATAGS_SIZE)) {
+		val = readl(addr);
+		if (val == ATAG_DDR_MEM_MAGIC)
+			break;
+		addr += 4;
+	}
+	if (addr >= (ATAGS_PHYS_BASE + ATAGS_SIZE))
+		return -ENODATA;
+
+	ddr_info = (void *)addr + 4;
+	if (!ddr_info->count || ddr_info->count > CONFIG_NR_DRAM_BANKS)
+		return -ENODATA;
+
+	for (int i = 0; i < (ddr_info->count); i++) {
+		size_t start_addr = ddr_info->bank[i];
+		size_t size = ddr_info->bank[(i + ddr_info->count)];
+		size_t tmp;
+
+		if (start_addr < SZ_2M) {
+			tmp = SZ_2M - start_addr;
+			start_addr = SZ_2M;
+			size = size - tmp;
+		}
+
+		if (start_addr >= SDRAM_MAX_SIZE && start_addr < SZ_4G)
+			start_addr = SZ_4G;
+
+		tmp = start_addr + size;
+		if (tmp > SDRAM_MAX_SIZE && tmp < SZ_4G)
+			size = SDRAM_MAX_SIZE - start_addr;
+
+		gd->bd->bi_dram[i].start = start_addr;
+		gd->bd->bi_dram[i].size = size;
+	}
+
+	return 0;
+}
+
 #ifndef CONFIG_TPL_BUILD
 int arch_cpu_init(void)
 {
-- 
2.34.1