[PATCH RFT v3 4/4] hwmon: (spd5118) Add support for reading SPD data
From: Guenter Roeck
Date: Fri May 31 2024 - 19:06:58 EST
Add support for reading SPD NVRAM data from SPD5118 (Jedec JESD300)
compliant memory modules. NVRAM write operation is not supported.
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
v3: New patch
RFT: I'd like to get some more test coverage before moving forward
with this patch. decode-dimms doesn't recognize the 'spd5118'
driver.
Documentation/hwmon/spd5118.rst | 8 ++
drivers/hwmon/spd5118.c | 146 +++++++++++++++++++++++++++++++-
2 files changed, 150 insertions(+), 4 deletions(-)
diff --git a/Documentation/hwmon/spd5118.rst b/Documentation/hwmon/spd5118.rst
index a15d75aa2066..ef7338f46575 100644
--- a/Documentation/hwmon/spd5118.rst
+++ b/Documentation/hwmon/spd5118.rst
@@ -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.
diff --git a/drivers/hwmon/spd5118.c b/drivers/hwmon/spd5118.c
index baa315172298..131002290ff3 100644
--- a/drivers/hwmon/spd5118.c
+++ b/drivers/hwmon/spd5118.c
@@ -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 +55,31 @@ 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 +381,111 @@ 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_AUTO,
+ .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 +519,7 @@ 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 +529,15 @@ 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 +561,15 @@ 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);
+ if (err) {
+ 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;
regcache_cache_bypass(regmap, true);
regmap_update_bits(regmap, SPD5118_REG_TEMP_CONFIG, SPD5118_TS_DISABLE,
@@ -469,7 +606,8 @@ 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);
--
2.39.2