[PATCH v3] riscv: spacemit: k1: probe dram size during boot phase.

[Huan Zhou]

Implement functionality to probe and calculate the DRAM size during the boot phase for the RISC-V spacemit K1 platform.
The `map_format_size` function extracts the memory density from a given value, while `ddr_get_density` aggregates the sizes of the memory chips.
The `dram_init` function initializes the global RAM base and size based on the detected DRAM density, ensuring proper memory configuration at boot.

Tested-by: Marcel Ziswiler <marcel at ziswiler.com> # BPI-F3 16G
Signed-off-by: Huan Zhou <me at per1cycle.org>
---
This patch introduce improvement for get dram size on spacemit k1 platform,
retrieving the dram size dynamically.
Have tested on Licheepi LPI3A 8G[1].

Links:
[1] https://gist.github.com/per1cycle/e4eab66ebb6f83fe5118e823367fce28 .

Changes in v3:
- Remove the inline attr in arch/riscv/cpu/k1/dram.c map_format_size().
- Add detailed commit message.
- Link to v2: https://lore.kernel.org/r/20250114-get-dram-size-v2-1-aba5a281ea28@per1cycle.org

Changes in v2:
- Fix bracker and return type in map_format_size() function.
- Add test log in the cover letter..
- Link to v1: https://lore.kernel.org/r/20250108-get-dram-size-v1-1-4bae32ecf756@per1cycle.org
---
 arch/riscv/cpu/k1/dram.c | 40 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/cpu/k1/dram.c b/arch/riscv/cpu/k1/dram.c
index c477c15cbfb19f0e3a0ee72985b602f5bda352d7..54d209ca277db7b304df04f81b12ae4efa400e45 100644
--- a/arch/riscv/cpu/k1/dram.c
+++ b/arch/riscv/cpu/k1/dram.c
@@ -4,17 +4,53 @@
  */
 
 #include <asm/global_data.h>
+#include <asm/io.h>
 #include <config.h>
+#include <bitfield.h>
 #include <fdt_support.h>
 #include <linux/sizes.h>
 
+#define DDR_BASE 0xC0000000
 DECLARE_GLOBAL_DATA_PTR;
 
+static phys_size_t map_format_size(u32 val)
+{
+	u32 tmp;
+
+	if (!(val & 0x1))
+		return 0;
+
+	tmp = bitfield_extract(val, 16, 5);
+	switch (tmp) {
+	case 0xd:
+		return 512;
+	case 0xe:
+		return 1024;
+	case 0xf:
+		return 2048;
+	case 0x10:
+		return 4096;
+	case 0x11:
+		return 8192;
+	default:
+		pr_info("Invalid DRAM density %x\n", val);
+		return 0;
+	}
+}
+
+phys_size_t ddr_get_density(void)
+{
+	phys_size_t cs0_size = map_format_size(readl((void *)DDR_BASE + 0x200));
+	phys_size_t cs1_size = map_format_size(readl((void *)DDR_BASE + 0x208));
+	phys_size_t ddr_size = cs0_size + cs1_size;
+
+	return ddr_size;
+}
+
 int dram_init(void)
 {
 	gd->ram_base = CFG_SYS_SDRAM_BASE;
-	/* TODO get ram size from ddr controller */
-	gd->ram_size = SZ_4G;
+	gd->ram_size = ddr_get_density() * SZ_1M;
 	return 0;
 }
 

---
base-commit: 19fc0b7f7d907119a13e9c207991899f0817f8fc
change-id: 20250108-get-dram-size-65cf59a15201

Best regards,
-- 
Huan Zhou <me at per1cycle.org>