[PATCH 0/4 v2] Instantiate SPD EEPROMs at boot on x86

[PATCH 0/4 v2] Instantiate SPD EEPROMs at boot on x86

[Jean Delvare]

This is my work to let decode-dimms work out of the box on most x86
desktop and laptop systems.

[PATCH 1/4] firmware: dmi: Remember the memory type
[PATCH 2/4] firmware: dmi: Add dmi_memdev_handle
[PATCH 3/4] i2c: smbus: Add a way to instantiate SPD EEPROMs automatically
[PATCH 4/4] i2c: i801: Instantiate SPD EEPROMs automatically

Changes since v1:
 * Fix build warning and error reported by kbuild test bot for specific
   kernel configurations

-- 
Jean Delvare
SUSE L3 Support

[PATCH 1/4] firmware: dmi: Remember the memory type

[Jean Delvare]

Store the memory type while walking the memory slots, and provide a
way to retrieve it later.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
---
 drivers/firmware/dmi_scan.c |   25 ++++++++++++++++++++++++-
 include/linux/dmi.h         |    2 ++
 2 files changed, 26 insertions(+), 1 deletion(-)

--- linux-5.3.orig/drivers/firmware/dmi_scan.c	2019-10-08 14:27:23.783640227 +0200
+++ linux-5.3/drivers/firmware/dmi_scan.c	2019-10-08 16:35:35.442803880 +0200
@@ -35,6 +35,7 @@ static struct dmi_memdev_info {
 	const char *bank;
 	u64 size;		/* bytes */
 	u16 handle;
+	u8 type;		/* DDR2, DDR3, DDR4 etc */
 } *dmi_memdev;
 static int dmi_memdev_nr;
 
@@ -391,7 +392,7 @@ static void __init save_mem_devices(cons
 	u64 bytes;
 	u16 size;
 
-	if (dm->type != DMI_ENTRY_MEM_DEVICE || dm->length < 0x12)
+	if (dm->type != DMI_ENTRY_MEM_DEVICE || dm->length < 0x13)
 		return;
 	if (nr >= dmi_memdev_nr) {
 		pr_warn(FW_BUG "Too many DIMM entries in SMBIOS table\n");
@@ -400,6 +401,7 @@ static void __init save_mem_devices(cons
 	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]);
+	dmi_memdev[nr].type = d[0x12];
 
 	size = get_unaligned((u16 *)&d[0xC]);
 	if (size == 0)
@@ -1128,3 +1130,24 @@ u64 dmi_memdev_size(u16 handle)
 	return ~0ull;
 }
 EXPORT_SYMBOL_GPL(dmi_memdev_size);
+
+/**
+ * dmi_memdev_type - get the memory type
+ * @handle: DMI structure handle
+ *
+ * Return the DMI memory type of the module in the slot associated with the
+ * given DMI handle, or 0x0 if no such DMI handle exists.
+ */
+u8 dmi_memdev_type(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].type;
+		}
+	}
+	return 0x0;	/* Not a valid value */
+}
+EXPORT_SYMBOL_GPL(dmi_memdev_type);
--- linux-5.3.orig/include/linux/dmi.h	2019-10-04 16:14:24.575714482 +0200
+++ linux-5.3/include/linux/dmi.h	2019-10-08 17:42:19.726907967 +0200
@@ -113,6 +113,7 @@ extern int dmi_walk(void (*decode)(const
 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);
+extern u8 dmi_memdev_type(u16 handle);
 
 #else
 
@@ -142,6 +143,7 @@ static inline bool dmi_match(enum dmi_fi
 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 u8 dmi_memdev_type(u16 handle) { return 0x0; }
 static inline const struct dmi_system_id *
 	dmi_first_match(const struct dmi_system_id *list) { return NULL; }
 

-- 
Jean Delvare
SUSE L3 Support

[PATCH 2/4] firmware: dmi: Add dmi_memdev_handle

[Jean Delvare]

Add a utility function dmi_memdev_handle() which returns the DMI
handle associated with a given memory slot. This will allow kernel
drivers to iterate over the memory slots.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
---
 drivers/firmware/dmi_scan.c |   16 ++++++++++++++++
 include/linux/dmi.h         |    2 ++
 2 files changed, 18 insertions(+)

--- linux-5.3.orig/drivers/firmware/dmi_scan.c	2019-10-10 11:33:02.871034637 +0200
+++ linux-5.3/drivers/firmware/dmi_scan.c	2019-10-10 11:45:37.275549638 +0200
@@ -1151,3 +1151,19 @@ u8 dmi_memdev_type(u16 handle)
 	return 0x0;	/* Not a valid value */
 }
 EXPORT_SYMBOL_GPL(dmi_memdev_type);
+
+/**
+ *	dmi_memdev_handle - get the DMI handle of a memory slot
+ *	@slot: slot number
+ *
+ *	Return the DMI handle associated with a given memory slot, or %0xFFFF
+ *      if there is no such slot.
+ */
+u16 dmi_memdev_handle(int slot)
+{
+	if (dmi_memdev && slot >= 0 && slot < dmi_memdev_nr)
+		return dmi_memdev[slot].handle;
+
+	return 0xffff;	/* Not a valid value */
+}
+EXPORT_SYMBOL_GPL(dmi_memdev_handle);
--- linux-5.3.orig/include/linux/dmi.h	2019-10-10 11:33:02.871034637 +0200
+++ linux-5.3/include/linux/dmi.h	2019-10-10 11:34:46.146337207 +0200
@@ -114,6 +114,7 @@ extern bool dmi_match(enum dmi_field f,
 extern void dmi_memdev_name(u16 handle, const char **bank, const char **device);
 extern u64 dmi_memdev_size(u16 handle);
 extern u8 dmi_memdev_type(u16 handle);
+extern u16 dmi_memdev_handle(int slot);
 
 #else
 
@@ -144,6 +145,7 @@ static inline void dmi_memdev_name(u16 h
 		const char **device) { }
 static inline u64 dmi_memdev_size(u16 handle) { return ~0ul; }
 static inline u8 dmi_memdev_type(u16 handle) { return 0x0; }
+static inline u16 dmi_memdev_handle(int slot) { return 0xffff; }
 static inline const struct dmi_system_id *
 	dmi_first_match(const struct dmi_system_id *list) { return NULL; }
 


-- 
Jean Delvare
SUSE L3 Support

[PATCH 3/4 v2] i2c: smbus: Add a way to instantiate SPD EEPROMs automatically

[Jean Delvare]

In simple cases we can instantiate SPD EEPROMs on the SMBus
automatically. Start with just DDR2, DDR3 and DDR4 on x86 for now,
and only for systems with no more than 4 memory slots. These
limitations may be lifted later.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
---
Changes since v1:
 * Fixed build warning reported by kbuild test bot

 drivers/i2c/i2c-smbus.c   |  104 +++++++++++++++++++++++++++++++++++++++++++++-
 include/linux/i2c-smbus.h |    8 +++
 2 files changed, 110 insertions(+), 2 deletions(-)

--- linux-5.3.orig/drivers/i2c/i2c-smbus.c	2019-10-14 11:33:20.372781769 +0200
+++ linux-5.3/drivers/i2c/i2c-smbus.c	2019-10-14 16:42:12.815302881 +0200
@@ -3,10 +3,11 @@
  * i2c-smbus.c - SMBus extensions to the I2C protocol
  *
  * Copyright (C) 2008 David Brownell
- * Copyright (C) 2010 Jean Delvare <jdelvare@suse.de>
+ * Copyright (C) 2010-2019 Jean Delvare <jdelvare@suse.de>
  */
 
 #include <linux/device.h>
+#include <linux/dmi.h>
 #include <linux/i2c.h>
 #include <linux/i2c-smbus.h>
 #include <linux/interrupt.h>
@@ -203,6 +204,107 @@ EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert
 
 module_i2c_driver(smbalert_driver);
 
+/*
+ * SPD is not part of SMBus but we include it here for convenience as the
+ * target systems are the same.
+ * Restrictions to automatic SPD instantiation:
+ *  - Only works if all filled slots have the same memory type
+ *  - Only works for DDR2, DDR3 and DDR4 for now
+ *  - Only works on systems with 1 to 4 memory slots
+ */
+#if IS_ENABLED(CONFIG_DMI)
+void i2c_register_spd(struct i2c_adapter *adap)
+{
+	int n, slot_count = 0, dimm_count = 0;
+	u16 handle;
+	u8 common_mem_type = 0x0, mem_type;
+	u64 mem_size;
+	const char *name;
+
+	while ((handle = dmi_memdev_handle(slot_count)) != 0xffff) {
+		slot_count++;
+
+		/* Skip empty slots */
+		mem_size = dmi_memdev_size(handle);
+		if (!mem_size)
+			continue;
+
+		/* Skip undefined memory type */
+		mem_type = dmi_memdev_type(handle);
+		if (mem_type <= 0x02)		/* Invalid, Other, Unknown */
+			continue;
+
+		if (!common_mem_type) {
+			/* First filled slot */
+			common_mem_type = mem_type;
+		} else {
+			/* Check that all filled slots have the same type */
+			if (mem_type != common_mem_type) {
+				dev_warn(&adap->dev,
+					 "Different memory types mixed, not instantiating SPD\n");
+				return;
+			}
+		}
+		dimm_count++;
+	}
+
+	/* No useful DMI data, bail out */
+	if (!dimm_count)
+		return;
+
+	dev_info(&adap->dev, "%d/%d memory slots populated (from DMI)\n",
+		 dimm_count, slot_count);
+
+	if (slot_count > 4) {
+		dev_warn(&adap->dev,
+			 "Systems with more than 4 memory slots not supported yet, not instantiating SPD\n");
+		return;
+	}
+
+	switch (common_mem_type) {
+	case 0x13:	/* DDR2 */
+	case 0x18:	/* DDR3 */
+	case 0x1C:	/* LPDDR2 */
+	case 0x1D:	/* LPDDR3 */
+		name = "spd";
+		break;
+	case 0x1A:	/* DDR4 */
+	case 0x1E:	/* LPDDR4 */
+		name = "ee1004";
+		break;
+	default:
+		dev_info(&adap->dev,
+			 "Memory type 0x%02x not supported yet, not instantiating SPD\n",
+			 common_mem_type);
+		return;
+	}
+
+	/*
+	 * We don't know in which slots the memory modules are. We could
+	 * try to guess from the slot names, but that would be rather complex
+	 * and unreliable, so better probe all possible addresses until we
+	 * have found all memory modules.
+	 */
+	for (n = 0; n < slot_count && dimm_count; n++) {
+		struct i2c_board_info info;
+		unsigned short addr_list[2];
+
+		memset(&info, 0, sizeof(struct i2c_board_info));
+		strlcpy(info.type, name, I2C_NAME_SIZE);
+		addr_list[0] = 0x50 + n;
+		addr_list[1] = I2C_CLIENT_END;
+
+		if (i2c_new_probed_device(adap, &info, addr_list, NULL)) {
+			dev_info(&adap->dev,
+				 "Successfully instantiated SPD at 0x%hx\n",
+				 addr_list[0]);
+			dimm_count--;
+		}
+	}
+}
+EXPORT_SYMBOL_GPL(i2c_register_spd);
+#endif
+
 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
 MODULE_DESCRIPTION("SMBus protocol extensions support");
 MODULE_LICENSE("GPL");
--- linux-5.3.orig/include/linux/i2c-smbus.h	2019-10-14 11:33:20.372781769 +0200
+++ linux-5.3/include/linux/i2c-smbus.h	2019-10-14 16:44:22.636959738 +0200
@@ -2,7 +2,7 @@
 /*
  * i2c-smbus.h - SMBus extensions to the I2C protocol
  *
- * Copyright (C) 2010 Jean Delvare <jdelvare@suse.de>
+ * Copyright (C) 2010-2019 Jean Delvare <jdelvare@suse.de>
  */
 
 #ifndef _LINUX_I2C_SMBUS_H
@@ -44,4 +44,10 @@ static inline int of_i2c_setup_smbus_ale
 }
 #endif
 
+#if IS_ENABLED(CONFIG_I2C_SMBUS) && IS_ENABLED(CONFIG_DMI)
+void i2c_register_spd(struct i2c_adapter *adap);
+#else
+static inline void i2c_register_spd(struct i2c_adapter *adap) { }
+#endif
+
 #endif /* _LINUX_I2C_SMBUS_H */

-- 
Jean Delvare
SUSE L3 Support

[PATCH 4/4 v2] i2c: i801: Instantiate SPD EEPROMs automatically

[Jean Delvare]

Call the function to instantiate SPD EEPROMs automatically on the
main SMBus controller.

Multiplexed SMBus systems are excluded for now as they are more
complex to handle.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
---
Changes since v1:
 * Fixed build error reported by kbuild test robot

 drivers/i2c/busses/i2c-i801.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- linux-5.4-rc7.orig/drivers/i2c/busses/i2c-i801.c	2019-11-18 10:21:39.688372006 +0100
+++ linux-5.4-rc7/drivers/i2c/busses/i2c-i801.c	2019-11-18 10:21:41.928402933 +0100
@@ -1320,6 +1320,12 @@ static void i801_probe_optional_slaves(s
 
 	if (is_dell_system_with_lis3lv02d())
 		register_dell_lis3lv02d_i2c_device(priv);
+
+	/* Instantiate SPD EEPROMs unless the SMBus is multiplexed */
+#if IS_ENABLED(CONFIG_I2C_MUX_GPIO)
+	if (!priv->mux_drvdata)
+#endif
+		i2c_register_spd(&priv->adapter);
 }
 #else
 static void __init input_apanel_init(void) {}

-- 
Jean Delvare
SUSE L3 Support