[PATCH v2 12/13] hwmon: spd5118: Add I3C support

Akhil R
2026-04-09T11:01:25Z

Add a regmap config and a probe function to support for I3C based
communication to SPD5118 devices.

On an I3C bus, SPD5118 are enumerated via SETAASA and always require an
ACPI or device tree entry. The device matching is hence through the OF
match tables only and do not need an I3C class match table. The device
identity is verified in the type registers before proceeding to the
common probe function.

Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
---
drivers/hwmon/Kconfig | 9 ++++---
drivers/hwmon/spd5118.c | 56 ++++++++++++++++++++++++++++++++++++++++-
2 files changed, 61 insertions(+), 4 deletions(-)

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 8af80e17d25e..7e8f419603df 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -2298,12 +2298,15 @@ config SENSORS_INA3221

config SENSORS_SPD5118
tristate "SPD5118 Compliant Temperature Sensors"
- depends on I2C
+ depends on I3C_OR_I2C
select REGMAP_I2C
+ select REGMAP_I3C if I3C
help
If you say yes here you get support for SPD5118 (JEDEC JESD300)
- compliant temperature sensors. Such sensors are found on DDR5 memory
- modules.
+ compliant temperature sensors using I2C or I3C bus interface.
+ Such sensors are found on DDR5 memory modules.
+
+ This driver supports both I2C and I3C interfaces.

This driver can also be built as a module. If so, the module
will be called spd5118.
diff --git a/drivers/hwmon/spd5118.c b/drivers/hwmon/spd5118.c
index 8fdde35e68cd..db66028d2f59 100644
--- a/drivers/hwmon/spd5118.c
+++ b/drivers/hwmon/spd5118.c
@@ -18,6 +18,7 @@
#include <linux/bits.h>
#include <linux/err.h>
#include <linux/i2c.h>
+#include <linux/i3c/device.h>
#include <linux/hwmon.h>
#include <linux/module.h>
#include <linux/mutex.h>
@@ -464,6 +465,27 @@ static const struct regmap_config spd5118_regmap8_config = {
.num_ranges = ARRAY_SIZE(spd5118_i2c_regmap_range_cfg),
};

+/*
+ * SPD5118 2-byte register address format (JESD300-5, Tables 7 & 20):
+ * Byte 1 (on wire first): MemReg | BlkAddr[0] | Address[5:0]
+ * Byte 2 (on wire second): 0000 | BlkAddr[4:1]
+ *
+ * The address byte (with MemReg and lower address bits) must be sent first,
+ * followed by the upper block address byte. With regmap 16-bit register
+ * format, this maps to little-endian: the low byte of the 16-bit value is
+ * transmitted first. No range config is needed since I3C does not use MR11
+ * page switching.
+ */
+static const struct regmap_config spd5118_regmap_i3c_config = {
+ .reg_bits = 16,
+ .val_bits = 8,
+ .max_register = 0x7ff,
+ .reg_format_endian = REGMAP_ENDIAN_LITTLE,
+ .writeable_reg = spd5118_writeable_reg,
+ .volatile_reg = spd5118_volatile_reg,
+ .cache_type = REGCACHE_MAPLE,
+};
+
static int spd5118_suspend(struct device *dev)
{
struct spd5118_data *data = dev_get_drvdata(dev);
@@ -701,7 +723,39 @@ static struct i2c_driver spd5118_i2c_driver = {
.address_list = IS_ENABLED(CONFIG_SENSORS_SPD5118_DETECT) ? normal_i2c : NULL,
};

-module_i2c_driver(spd5118_i2c_driver);
+/* I3C */
+
+static int spd5118_i3c_probe(struct i3c_device *i3cdev)
+{
+ struct device *dev = i3cdev_to_dev(i3cdev);
+ struct regmap *regmap;
+ u8 regval[2];
+ int err;
+
+ regmap = devm_regmap_init_i3c(i3cdev, &spd5118_regmap_i3c_config);
+ if (IS_ERR(regmap))
+ return dev_err_probe(dev, PTR_ERR(regmap), "regmap init failed\n");
+
+ err = regmap_bulk_read(regmap, SPD5118_REG_TYPE, regval, 2);
+ if (err)
+ return err;
+
+ if (regval[0] != 0x51 || regval[1] != 0x18)
+ return -ENODEV;
+
+ return spd5118_common_probe(dev, regmap);
+}
+
+static struct i3c_driver spd5118_i3c_driver = {
+ .driver = {
+ .name = "spd5118_i3c",
+ .of_match_table = spd5118_of_ids,
+ .pm = pm_sleep_ptr(&spd5118_pm_ops),
+ },
+ .probe = spd5118_i3c_probe,
+};
+
+module_i3c_i2c_driver(spd5118_i3c_driver, &spd5118_i2c_driver);

MODULE_AUTHOR("René Rebe <rene@exactcode.de>");
MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
--
2.50.1