[PATCH 2/2] hwmon: pmbus: Add ltc4286 driver

[Delphine CC Chiu <Delphine_CC_Chiu@Wiwynn.com>]

Add a driver to support ltc4286 chip

Signed-off-by: Delphine CC Chiu <Delphine_CC_Chiu@Wiwynn.com>
---
 drivers/hwmon/pmbus/Kconfig   |   9 +++
 drivers/hwmon/pmbus/Makefile  |   1 +
 drivers/hwmon/pmbus/ltc4286.c | 147 ++++++++++++++++++++++++++++++++++
 3 files changed, 157 insertions(+)
 create mode 100644 drivers/hwmon/pmbus/ltc4286.c

diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
index 270b6336b76d..7cb9cbff587d 100644
--- a/drivers/hwmon/pmbus/Kconfig
+++ b/drivers/hwmon/pmbus/Kconfig
@@ -226,6 +226,15 @@ config SENSORS_LTC3815
 
 	  This driver can also be built as a module. If so, the module will
 	  be called ltc3815.
+config SENSORS_LTC4286
+	bool "Analog Devices LTC4286"
+	help
+	  LTC4286 is an integrated solution for hot swap applications that
+	  allows a board to be safely inserted and removed from a
+	  live backplane.
+	  This chip could be used to monitor voltage, current, ...etc.
+	  If you say yes here you get hardware monitoring support for Analog
+	  Devices LTC4286.
 
 config SENSORS_MAX15301
 	tristate "Maxim MAX15301"
diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
index 84ee960a6c2d..94e28f6d6a61 100644
--- a/drivers/hwmon/pmbus/Makefile
+++ b/drivers/hwmon/pmbus/Makefile
@@ -24,6 +24,7 @@ obj-$(CONFIG_SENSORS_LM25066)	+= lm25066.o
 obj-$(CONFIG_SENSORS_LT7182S)	+= lt7182s.o
 obj-$(CONFIG_SENSORS_LTC2978)	+= ltc2978.o
 obj-$(CONFIG_SENSORS_LTC3815)	+= ltc3815.o
+obj-$(CONFIG_SENSORS_LTC4286)	+= ltc4286.o
 obj-$(CONFIG_SENSORS_MAX15301)	+= max15301.o
 obj-$(CONFIG_SENSORS_MAX16064)	+= max16064.o
 obj-$(CONFIG_SENSORS_MAX16601)	+= max16601.o
diff --git a/drivers/hwmon/pmbus/ltc4286.c b/drivers/hwmon/pmbus/ltc4286.c
new file mode 100644
index 000000000000..b86bf31cfbae
--- /dev/null
+++ b/drivers/hwmon/pmbus/ltc4286.c
@@ -0,0 +1,147 @@
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pmbus.h>
+#include "pmbus.h"
+
+/* LTC4286 register */
+#define LTC4286_MFR_CONFIG1	0xF2
+
+/* LTC4286 configuration */
+#define VRANGE_SELECT_BIT	BIT(1)
+
+#define LTC4286_MFR_ID_SIZE	3
+
+enum chips { ltc4286, ltc4287 };
+
+/*
+ * Initialize the MBR as default settings which is referred to LTC4286 datasheet
+ * (March 22, 2022 version) table 3 page 16
+ */
+static struct pmbus_driver_info ltc4286_info = {
+	.pages = 1,
+	.format[PSC_VOLTAGE_IN] = direct,
+	.format[PSC_VOLTAGE_OUT] = direct,
+	.format[PSC_CURRENT_OUT] = direct,
+	.format[PSC_POWER] = direct,
+	.format[PSC_TEMPERATURE] = direct,
+	.m[PSC_VOLTAGE_IN] = 32,
+	.b[PSC_VOLTAGE_IN] = 0,
+	.R[PSC_VOLTAGE_IN] = 1,
+	.m[PSC_VOLTAGE_OUT] = 32,
+	.b[PSC_VOLTAGE_OUT] = 0,
+	.R[PSC_VOLTAGE_OUT] = 1,
+	.m[PSC_CURRENT_OUT] = 1024,
+	.b[PSC_CURRENT_OUT] = 0,
+	.R[PSC_CURRENT_OUT] = 3 - 6, /* To support small shunt resistor value */
+	.m[PSC_POWER] = 1,
+	.b[PSC_POWER] = 0,
+	.R[PSC_POWER] = 4 - 6, /* To support small shunt resistor value */
+	.m[PSC_TEMPERATURE] = 1,
+	.b[PSC_TEMPERATURE] = 273,
+	.R[PSC_TEMPERATURE] = 0,
+	.func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT |
+		   PMBUS_HAVE_PIN | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_VOUT |
+		   PMBUS_HAVE_STATUS_IOUT | PMBUS_HAVE_STATUS_TEMP,
+};
+
+static const struct i2c_device_id ltc4286_id[] = { { "ltc4286", ltc4286 },
+						   { "ltc4287", ltc4287 },
+						   {} };
+MODULE_DEVICE_TABLE(i2c, ltc4286_id);
+
+static int ltc4286_probe(struct i2c_client *client)
+{
+	int ret;
+	u8 block_buffer[I2C_SMBUS_BLOCK_MAX + 1];
+	struct pmbus_driver_info *info;
+	u32 rsense;
+
+	ret = i2c_smbus_read_block_data(client, PMBUS_MFR_ID, block_buffer);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed to read manufacturer id\n");
+		return ret;
+	}
+
+	/*
+	 * Refer to ltc4286 datasheet page 20
+	 * the manufacturer id is LTC
+	 */
+	if (ret != LTC4286_MFR_ID_SIZE ||
+	    strncmp(block_buffer, "LTC", LTC4286_MFR_ID_SIZE)) {
+		return dev_err_probe(&client->dev, err,
+				     "failed to read manufacturer id\n");
+	}
+
+	ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, block_buffer);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed to read manufacturer model\n");
+		return ret;
+	}
+
+	for (mid = ltc4286_id; mid->name[0]; mid++) {
+		if (!strncasecmp(mid->name, block_buffer, strlen(mid->name)))
+			break;
+	}
+
+	ret = of_property_read_u32(client->dev.of_node,
+				   "shunt-resistor-micro-ohms", &rsense);
+	if (ret < 0)
+		return ret;
+
+	if (rsense == 0)
+		return -EINVAL;
+
+	info = &ltc4286_info;
+
+	/* Default of VRANGE_SELECT = 1, 102.4V */
+	if (device_property_read_bool(client->dev, "vrange_select_25p6")) {
+		/* Setup MFR1 CONFIG register bit 1 VRANGE_SELECT */
+		ret = i2c_smbus_read_word_data(client, LTC4286_MFR_CONFIG1);
+		if (ret < 0) {
+			dev_err(&client->dev,
+				"failed to read manufacturer configuration one\n");
+			return ret;
+		}
+
+		ret &= ~VRANGE_SELECT; /* VRANGE_SELECT = 0, 25.6V */
+		ret = i2c_smbus_write_word_data(client, LTC4286_MFR_CONFIG1,
+						ret);
+		if (ret < 0) {
+			dev_err(&client->dev, "failed to set vrange\n");
+			return ret;
+		}
+
+		info->m[PSC_VOLTAGE_IN] = 128;
+		info->m[PSC_VOLTAGE_OUT] = 128;
+		info->m[PSC_POWER] = 4 * rsense;
+	} else
+		info->m[PSC_POWER] = rsense;
+
+	info->m[PSC_CURRENT_OUT] = 1024 * rsense;
+
+	return pmbus_do_probe(client, info);
+}
+
+static const struct of_device_id ltc4286_of_match[] = {
+	{ .compatible = "lltc,ltc4286" },
+	{ .compatible = "lltc,ltc4287" },
+	{}
+};
+
+static struct i2c_driver ltc4286_driver = {
+	.driver = {
+		.name = "ltc4286",
+		.of_match_table = ltc4286_of_match,
+	},
+	.probe = ltc4286_probe,
+	.id_table = ltc4286_id,
+};
+
+module_i2c_driver(ltc4286_driver);
+
+MODULE_AUTHOR("Delphine CC Chiu <Delphine_CC_Chiu@wiwynn.com>");
+MODULE_DESCRIPTION("PMBUS driver for LTC4286 and compatibles");
+MODULE_LICENSE("GPL");
-- 
2.25.1