[openwrt/openwrt] realtek: determine memory size during initialization

[LEDE Commits]

hauke pushed a commit to openwrt/openwrt.git, branch main:
https://git.openwrt.org/88e79af543cd0da4357b4327c694375c9b9610c6

commit 88e79af543cd0da4357b4327c694375c9b9610c6
Author: Markus Stockhausen <markus.stockhausen at gmx.de>
AuthorDate: Tue Dec 30 10:33:32 2025 +0100

    realtek: determine memory size during initialization
    
    For proper highmem initialization on RTL930x the size of the
    installed memory is needed during early bootup. Enhance the
    soc_info structure and fill the data from the registers.
    
    While we are here remove the obsolete compatible variable from
    the soc_info structure.
    
    Adapt boot message to show the memory size.
    
    old: SoC Type: Realtek RTL9301 rev B (6487)
    new: Realtek RTL9301 rev B (6487) SoC with 512 MB
    
    Signed-off-by: Markus Stockhausen <markus.stockhausen at gmx.de>
    Link: https://github.com/openwrt/openwrt/pull/21327
    Signed-off-by: Hauke Mehrtens <hauke at hauke-m.de>
---
 .../mips/include/asm/mach-rtl838x/mach-rtl83xx.h   |  2 +-
 .../realtek/files-6.12/arch/mips/rtl838x/prom.c    | 26 +++++++++++++++++++++-
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/target/linux/realtek/files-6.12/arch/mips/include/asm/mach-rtl838x/mach-rtl83xx.h b/target/linux/realtek/files-6.12/arch/mips/include/asm/mach-rtl838x/mach-rtl83xx.h
index 0a98399591..8639661a94 100644
--- a/target/linux/realtek/files-6.12/arch/mips/include/asm/mach-rtl838x/mach-rtl83xx.h
+++ b/target/linux/realtek/files-6.12/arch/mips/include/asm/mach-rtl838x/mach-rtl83xx.h
@@ -48,8 +48,8 @@ struct rtl83xx_soc_info {
 	unsigned int revision;
 	unsigned int cpu;
 	bool testchip;
-	unsigned char *compatible;
 	int cpu_port;
+	int memory_size;
 };
 
 #endif /* _MACH_RTL838X_H_ */
diff --git a/target/linux/realtek/files-6.12/arch/mips/rtl838x/prom.c b/target/linux/realtek/files-6.12/arch/mips/rtl838x/prom.c
index 94d659913c..f8c13ee49f 100644
--- a/target/linux/realtek/files-6.12/arch/mips/rtl838x/prom.c
+++ b/target/linux/realtek/files-6.12/arch/mips/rtl838x/prom.c
@@ -17,6 +17,13 @@
 
 #include <mach-rtl83xx.h>
 
+#define RTL_SOC_BASE			((volatile void *) 0xB8000000)
+#define RTL83XX_DRAM_CONFIG		0x1004
+#define RTL931X_DRAM_CONFIG		0x14304c
+
+#define soc_r32(reg)			readl(RTL_SOC_BASE + reg)
+#define soc_w32(val, reg)		writel(val, RTL_SOC_BASE + reg)
+
 struct rtl83xx_soc_info soc_info;
 const void *fdt;
 
@@ -228,14 +235,31 @@ static void __init set_system_type(void)
 		 soc_info.name, es, revision, soc_info.cpu);
 }
 
+static void get_system_memory(void)
+{
+	unsigned int dcr, bits;
+
+	if (soc_info.family == RTL9310_FAMILY_ID) {
+		dcr = soc_r32(RTL931X_DRAM_CONFIG);
+		bits = (dcr >> 12) + ((dcr >> 6) & 0x3f) + (dcr & 0x3f);
+	} else {
+		dcr = soc_r32(RTL83XX_DRAM_CONFIG);
+		bits = ((dcr >> 28) & 0x3) + ((dcr >> 24) & 0x3) +
+		       ((dcr >> 20) & 0xf) + ((dcr >> 16) & 0xf) + 20;
+	}
+
+	soc_info.memory_size = 1 << bits;
+}
+
 void __init prom_init(void)
 {
 	u32 model = read_model();
 
 	parse_model(model);
 	set_system_type();
+	get_system_memory();
 
-	pr_info("SoC Type: %s\n", get_system_type());
+	pr_info("%s SoC with %d MB\n", get_system_type(), soc_info.memory_size >> 20);
 
 	/*
 	 * fw_arg2 is be the pointer to the environment. Some devices (e.g. HP JG924A) hand