[PATCH 11/12] hwmon: spd5118: Add I3C support

[Akhil R <akhilrajeev@nvidia.com>]

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   |  7 +++--
 drivers/hwmon/spd5118.c | 66 ++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 70 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 8af80e17d25e..23604c05ad22 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -2300,10 +2300,13 @@ config SENSORS_SPD5118
 	tristate "SPD5118 Compliant Temperature Sensors"
 	depends on 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 5da44571b6a0..d70123e10616 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>
@@ -482,6 +483,25 @@ static const struct regmap_config spd5118_regmap16_config = {
 	.cache_type = REGCACHE_MAPLE,
 };
 
+/*
+ * I3C uses 2-byte register addressing -
+ *   Byte 1: MemReg | BlkAddr[0] | Address[5:0]
+ *   Byte 2: 0000   | BlkAddr[4:1]
+ *
+ * The low byte carries the register/NVM address and the high byte carries the
+ * upper block address bits, so little-endian format is required. 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);
@@ -770,7 +790,51 @@ 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;
+	unsigned int regval;
+	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");
+
+	/* Verify this is a SPD5118 device */
+	err = regmap_read(regmap, SPD5118_REG_TYPE, &regval);
+	if (err)
+		return err;
+
+	if (regval != 0x51) {
+		dev_err(dev, "unexpected device type 0x%02x, expected 0x51\n", regval);
+		return -ENODEV;
+	}
+
+	err = regmap_read(regmap, SPD5118_REG_TYPE + 1, &regval);
+	if (err)
+		return err;
+
+	if (regval != 0x18) {
+		dev_err(dev, "unexpected device type 0x%02x, expected 0x18\n", regval);
+		return -ENODEV;
+	}
+
+	return spd5118_common_probe(dev, regmap, false);
+}
+
+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