firmware, DMI: Add function to look up a handle and return DIMM size

When we first scan the SMBIOS table, save the size of the DIMM.

Provide a function for other code (EDAC driver) to look up the size
of a DIMM from its SMBIOS handle.

Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Cc: Aristeu Rozanski <aris@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: linux-acpi@vger.kernel.org
Cc: linux-nvdimm@lists.01.org
Link: http://lkml.kernel.org/r/20180312182430.10335-5-tony.luck@intel.com
Signed-off-by: Borislav Petkov <bp@suse.de>

drivers/firmware/dmi_scan.c

@@ -32,6 +32,7 @@ static char dmi_ids_string[128] __initdata;
 static struct dmi_memdev_info {
 	const char *device;
 	const char *bank;
+	u64 size;		/* bytes */
 	u16 handle;
 } *dmi_memdev;
 static int dmi_memdev_nr;
@@ -386,6 +387,8 @@ static void __init save_mem_devices(const struct dmi_header *dm, void *v)
 {
 	const char *d = (const char *)dm;
 	static int nr;
+	u64 bytes;
+	u16 size;
 
 	if (dm->type != DMI_ENTRY_MEM_DEVICE || dm->length < 0x12)
 		return;
@@ -396,6 +399,20 @@ static void __init save_mem_devices(const struct dmi_header *dm, void *v)
 	dmi_memdev[nr].handle = get_unaligned(&dm->handle);
 	dmi_memdev[nr].device = dmi_string(dm, d[0x10]);
 	dmi_memdev[nr].bank = dmi_string(dm, d[0x11]);
+
+	size = get_unaligned((u16 *)&d[0xC]);
+	if (size == 0)
+		bytes = 0;
+	else if (size == 0xffff)
+		bytes = ~0ull;
+	else if (size & 0x8000)
+		bytes = (u64)(size & 0x7fff) << 10;
+	else if (size != 0x7fff)
+		bytes = (u64)size << 20;
+	else
+		bytes = (u64)get_unaligned((u32 *)&d[0x1C]) << 20;
+
+	dmi_memdev[nr].size = bytes;
 	nr++;
 }
 
@@ -1065,3 +1082,17 @@ void dmi_memdev_name(u16 handle, const char **bank, const char **device)
 	}
 }
 EXPORT_SYMBOL_GPL(dmi_memdev_name);
+
+u64 dmi_memdev_size(u16 handle)
+{
+	int n;
+
+	if (dmi_memdev) {
+		for (n = 0; n < dmi_memdev_nr; n++) {
+			if (handle == dmi_memdev[n].handle)
+				return dmi_memdev[n].size;
+		}
+	}
+	return ~0ull;
+}
+EXPORT_SYMBOL_GPL(dmi_memdev_size);

include/linux/dmi.h

@@ -113,6 +113,7 @@ extern int dmi_walk(void (*decode)(const struct dmi_header *, void *),
 	void *private_data);
 extern bool dmi_match(enum dmi_field f, const char *str);
 extern void dmi_memdev_name(u16 handle, const char **bank, const char **device);
+extern u64 dmi_memdev_size(u16 handle);
 
 #else
 
@@ -142,6 +143,7 @@ static inline bool dmi_match(enum dmi_field f, const char *str)
 	{ return false; }
 static inline void dmi_memdev_name(u16 handle, const char **bank,
 		const char **device) { }
+static inline u64 dmi_memdev_size(u16 handle) { return ~0ul; }
 static inline const struct dmi_system_id *
 	dmi_first_match(const struct dmi_system_id *list) { return NULL; }