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hwmon: (spd5118) Add support for reading SPD data

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Add support for reading SPD NVMEM data from SPD5118 (Jedec JESD300)
compliant memory modules. NVMEM write operation is not supported.

NVMEM support is optional. If CONFIG_NVMEM is disabled, the driver will
still instantiate but not provide NVMEM attribute files.

Reviewed-by: Thomas Weißschuh <linux@weissschuh.net>
Tested-by: Armin Wolf <W_Armin@gmx.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Guenter Roeck 2024-05-31 09:55:37 -07:00
parent d1b4c75508
commit 25dff444c6
2 changed files with 150 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
Documentation/hwmon/spd5118.rst
View File

@ -53,3 +53,11 @@ temp1_crit_alarm Temperature critical alarm
Alarm attributes are sticky until read and will be cleared afterwards
unless the alarm condition still applies.
SPD (Serial Presence Detect) support
------------------------------------
The driver also supports reading the SPD NVRAM on SPD5118 compatible chips.
SPD data is available from the 'eeprom' binary attribute file attached to the
chip's I2C device.

146
drivers/hwmon/spd5118.c
View File

@ -20,6 +20,8 @@
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/nvmem-provider.h>
#include <linux/pm.h>
#include <linux/regmap.h>
#include <linux/units.h>
@ -53,12 +55,30 @@ static const unsigned short normal_i2c[] = {
#define SPD5118_TS_DISABLE BIT(0) /* temperature sensor disable */
#define SPD5118_LEGACY_MODE_ADDR BIT(3)
#define SPD5118_LEGACY_PAGE_MASK GENMASK(2, 0)
#define SPD5118_LEGACY_MODE_MASK (SPD5118_LEGACY_MODE_ADDR | SPD5118_LEGACY_PAGE_MASK)
#define SPD5118_NUM_PAGES 8
#define SPD5118_PAGE_SIZE 128
#define SPD5118_PAGE_SHIFT 7
#define SPD5118_PAGE_MASK GENMASK(6, 0)
#define SPD5118_EEPROM_BASE 0x80
#define SPD5118_EEPROM_SIZE (SPD5118_PAGE_SIZE * SPD5118_NUM_PAGES)
/* Temperature unit in millicelsius */
#define SPD5118_TEMP_UNIT (MILLIDEGREE_PER_DEGREE / 4)
/* Representable temperature range in millicelsius */
#define SPD5118_TEMP_RANGE_MIN -256000
#define SPD5118_TEMP_RANGE_MAX 255750
struct spd5118_data {
struct regmap *regmap;
struct mutex nvmem_lock;
};
/* hwmon */
static int spd5118_temp_from_reg(u16 reg)
{
int temp = sign_extend32(reg >> 2, 10);
@ -360,9 +380,111 @@ static const struct hwmon_chip_info spd5118_chip_info = {
.info = spd5118_info,
};
/* nvmem */
static int spd5118_nvmem_set_page(struct regmap *regmap, int page)
{
unsigned int old_page;
int err;
err = regmap_read(regmap, SPD5118_REG_I2C_LEGACY_MODE, &old_page);
if (err)
return err;
if (page != (old_page & SPD5118_LEGACY_MODE_MASK)) {
/* Update page and explicitly select 1-byte addressing */
err = regmap_update_bits(regmap, SPD5118_REG_I2C_LEGACY_MODE,
SPD5118_LEGACY_MODE_MASK, page);
if (err)
return err;
/* Selected new NVMEM page, drop cached data */
regcache_drop_region(regmap, SPD5118_EEPROM_BASE, 0xff);
}
return 0;
}
static ssize_t spd5118_nvmem_read_page(struct regmap *regmap, char *buf,
unsigned int offset, size_t count)
{
int err;
err = spd5118_nvmem_set_page(regmap, offset >> SPD5118_PAGE_SHIFT);
if (err)
return err;
offset &= SPD5118_PAGE_MASK;
/* Can't cross page boundaries */
if (offset + count > SPD5118_PAGE_SIZE)
count = SPD5118_PAGE_SIZE - offset;
err = regmap_bulk_read(regmap, SPD5118_EEPROM_BASE + offset, buf, count);
if (err)
return err;
return count;
}
static int spd5118_nvmem_read(void *priv, unsigned int off, void *val, size_t count)
{
struct spd5118_data *data = priv;
char *buf = val;
int ret;
if (unlikely(!count))
return count;
if (off + count > SPD5118_EEPROM_SIZE)
return -EINVAL;
mutex_lock(&data->nvmem_lock);
while (count) {
ret = spd5118_nvmem_read_page(data->regmap, buf, off, count);
if (ret < 0) {
mutex_unlock(&data->nvmem_lock);
return ret;
}
buf += ret;
off += ret;
count -= ret;
}
mutex_unlock(&data->nvmem_lock);
return 0;
}
static int spd5118_nvmem_init(struct device *dev, struct spd5118_data *data)
{
struct nvmem_config nvmem_config = {
.type = NVMEM_TYPE_EEPROM,
.name = dev_name(dev),
.id = NVMEM_DEVID_NONE,
.dev = dev,
.base_dev = dev,
.read_only = true,
.root_only = false,
.owner = THIS_MODULE,
.compat = true,
.reg_read = spd5118_nvmem_read,
.priv = data,
.stride = 1,
.word_size = 1,
.size = SPD5118_EEPROM_SIZE,
};
struct nvmem_device *nvmem;
nvmem = devm_nvmem_register(dev, &nvmem_config);
return PTR_ERR_OR_ZERO(nvmem);
}
/* regmap */
static bool spd5118_writeable_reg(struct device *dev, unsigned int reg)
{
switch (reg) {
case SPD5118_REG_I2C_LEGACY_MODE:
case SPD5118_REG_TEMP_CLR:
case SPD5118_REG_TEMP_CONFIG:
case SPD5118_REG_TEMP_MAX:
@ -396,7 +518,7 @@ static bool spd5118_volatile_reg(struct device *dev, unsigned int reg)
static const struct regmap_config spd5118_regmap_config = {
.reg_bits = 8,
.val_bits = 8,
.max_register = SPD5118_REG_TEMP_STATUS,
.max_register = 0xff,
.writeable_reg = spd5118_writeable_reg,
.volatile_reg = spd5118_volatile_reg,
.cache_type = REGCACHE_MAPLE,
@ -406,10 +528,15 @@ static int spd5118_probe(struct i2c_client *client)
{
struct device *dev = &client->dev;
unsigned int regval, revision, vendor, bank;
struct spd5118_data *data;
struct device *hwmon_dev;
struct regmap *regmap;
int err;
data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
regmap = devm_regmap_init_i2c(client, &spd5118_regmap_config);
if (IS_ERR(regmap))
return dev_err_probe(dev, PTR_ERR(regmap), "regmap init failed\n");
@ -433,7 +560,16 @@ static int spd5118_probe(struct i2c_client *client)
if (!spd5118_vendor_valid(bank, vendor))
return -ENODEV;
dev_set_drvdata(dev, regmap);
data->regmap = regmap;
mutex_init(&data->nvmem_lock);
dev_set_drvdata(dev, data);
err = spd5118_nvmem_init(dev, data);
/* Ignore if NVMEM support is disabled */
if (err && err != -EOPNOTSUPP) {
dev_err_probe(dev, err, "failed to register nvmem\n");
return err;
}
hwmon_dev = devm_hwmon_device_register_with_info(dev, "spd5118",
regmap, &spd5118_chip_info,
@ -454,7 +590,8 @@ static int spd5118_probe(struct i2c_client *client)
static int spd5118_suspend(struct device *dev)
{
struct regmap *regmap = dev_get_drvdata(dev);
struct spd5118_data *data = dev_get_drvdata(dev);
struct regmap *regmap = data->regmap;
u32 regval;
int err;
@ -479,7 +616,8 @@ static int spd5118_suspend(struct device *dev)
static int spd5118_resume(struct device *dev)
{
struct regmap *regmap = dev_get_drvdata(dev);
struct spd5118_data *data = dev_get_drvdata(dev);
struct regmap *regmap = data->regmap;
regcache_cache_only(regmap, false);
return regcache_sync(regmap);