libpayload: Add API to get physical memory size

sysinfo contains both CBMEM_ID_MEMINFO and CBMEM_ID_MEM_CHIP.
This new function allows to easily retrieve the amount of memory the
system has based on the mentioned CBMEM entries structures.

BUG=b:450374306
TEST=Checked on Google/Brya/Omnigul (x86) - MEMINFO
TEST=Checked on Google/Rauru/Navi (ARM64) - MEM_CHIP

Change-Id: Iaf69c54dfb3d2eaffbccacee8bee3be425b78a3f
Signed-off-by: Jakub Czapiga <czapiga@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/90430
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

payloads/libpayload/include/libpayload.h

@@ -493,6 +493,15 @@ u8 *sha1(const u8 *data, size_t len, u8 *buf);
  */
 
 int sysinfo_have_multiboot(unsigned long *addr);
+
+/**
+ * Check CBMEM_ID_MEM_CHIP and CBMEM_ID_MEMINFO, extract physical memory size
+ * present in the system.
+ *
+ * @returns physical memory detected in the system or zero in case of failure
+ */
+size_t sysinfo_get_physical_memory_size_mib(void);
+
 /** @} */
 
 /**

payloads/libpayload/libc/sysinfo.c

@@ -34,3 +34,23 @@ int sysinfo_have_multiboot(unsigned long *addr)
 	*addr = (unsigned long) lib_sysinfo.mbtable;
 	return (lib_sysinfo.mbtable == 0) ? 0 : 1;
 }
+
+size_t sysinfo_get_physical_memory_size_mib(void)
+{
+	const struct mem_chip_info *mc = phys_to_virt(lib_sysinfo.mem_chip_base);
+
+	if (mc)
+		return mem_chip_info_total_density_bytes(mc) / MiB;
+
+#if CONFIG(LP_GPL)
+	const struct memory_info *memory_info = phys_to_virt(lib_sysinfo.memory_info);
+	size_t memory_size_mib = 0;
+	if (memory_info) {
+		for (int i = 0; i < memory_info->dimm_cnt; ++i)
+			memory_size_mib += memory_info->dimm[i].dimm_size;
+		return memory_size_mib;
+	}
+#endif
+
+	return 0;
+}