[PATCH 2/4] rockchip: rk3576: Implement checkboard() to print SoC variant

[Jonas Karlman]

Implement checkboard() to print current SoC model used by a board when
U-Boot proper is running.

  U-Boot 2025.04 (Apr 22 2025 - 20:43:17 +0000)

  Model: Generic RK3576
  SoC:   RK3576
  DRAM:  8 GiB

Information about the SoC model and variant is read from OTP.

Also update rk3576-u-boot.dtsi to include OTP in U-Boot pre-reloc phase,
where checkboard() is called.

Signed-off-by: Jonas Karlman <jo...@kwiboo.se>
---
 arch/arm/dts/rk3576-u-boot.dtsi        |  4 +++
 arch/arm/mach-rockchip/rk3576/rk3576.c | 48 ++++++++++++++++++++++++++
 2 files changed, 52 insertions(+)

diff --git a/arch/arm/dts/rk3576-u-boot.dtsi b/arch/arm/dts/rk3576-u-boot.dtsi
index 928960862597..c623bf544688 100644
--- a/arch/arm/dts/rk3576-u-boot.dtsi
+++ b/arch/arm/dts/rk3576-u-boot.dtsi
@@ -56,6 +56,10 @@
        bootph-all;
 };
 
+&otp {
+       bootph-some-ram;
+};
+
 &pcfg_pull_none {
        bootph-all;
 };
diff --git a/arch/arm/mach-rockchip/rk3576/rk3576.c 
b/arch/arm/mach-rockchip/rk3576/rk3576.c
index ba5c94b4b3dd..2b1318f9532f 100644
--- a/arch/arm/mach-rockchip/rk3576/rk3576.c
+++ b/arch/arm/mach-rockchip/rk3576/rk3576.c
@@ -3,6 +3,10 @@
  * Copyright (c) 2024 Rockchip Electronics Co., Ltd
  */
 
+#define LOG_CATEGORY LOGC_ARCH
+
+#include <dm.h>
+#include <misc.h>
 #include <asm/armv8/mmu.h>
 #include <asm/arch-rockchip/bootrom.h>
 #include <asm/arch-rockchip/hardware.h>
@@ -153,3 +157,47 @@ int arch_cpu_init(void)
 
        return 0;
 }
+
+#define RK3576_OTP_CPU_CODE_OFFSET             0x02
+#define RK3576_OTP_SPECIFICATION_OFFSET                0x08
+
+int checkboard(void)
+{
+       u8 cpu_code[2], specification;
+       struct udevice *dev;
+       char suffix[2];
+       int ret;
+
+       if (!IS_ENABLED(CONFIG_ROCKCHIP_OTP) || !CONFIG_IS_ENABLED(MISC))
+               return 0;
+
+       ret = uclass_get_device_by_driver(UCLASS_MISC,
+                                         DM_DRIVER_GET(rockchip_otp), &dev);
+       if (ret) {
+               log_debug("Could not find otp device, ret=%d\n", ret);
+               return 0;
+       }
+
+       /* cpu-code: SoC model, e.g. 0x35 0x76 */
+       ret = misc_read(dev, RK3576_OTP_CPU_CODE_OFFSET, cpu_code, 2);
+       if (ret < 0) {
+               log_debug("Could not read cpu-code, ret=%d\n", ret);
+               return 0;
+       }
+
+       /* specification: SoC variant, e.g. 0xA for RK3576J */
+       ret = misc_read(dev, RK3576_OTP_SPECIFICATION_OFFSET, &specification, 
1);
+       if (ret < 0) {
+               log_debug("Could not read specification, ret=%d\n", ret);
+               return 0;
+       }
+       specification &= 0x1f;
+
+       /* for RK3576J i.e. '@' + 0xA = 'J' */
+       suffix[0] = specification > 1 ? '@' + specification : '\0';
+       suffix[1] = '\0';
+
+       printf("SoC:   RK%02x%02x%s\n", cpu_code[0], cpu_code[1], suffix);
+
+       return 0;
+}
-- 
2.49.0