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i2c: smbus: Add a way to instantiate SPD EEPROMs automatically

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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>
[wsa: minor change for new API]
Signed-off-by: Wolfram Sang <wsa@kernel.org>
This commit is contained in:
Jean Delvare 2020-03-16 11:22:24 +01:00 committed by Wolfram Sang
parent 7df915e540
commit 5ace60859e
2 changed files with 110 additions and 2 deletions
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104
drivers/i2c/i2c-smbus.c
View File

@ -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>
@ -196,6 +197,107 @@ 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 (!IS_ERR(i2c_new_scanned_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");

8
include/linux/i2c-smbus.h
View File

@ -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
@ -39,4 +39,10 @@ static inline int of_i2c_setup_smbus_alert(struct i2c_adapter *adap)
}
#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 */