[PATCH 1/2] hwmon: Add driver for EMC181x temperature sensors

[Mark Tomlinson]

This patch adds a HWMON driver for the EMC1812, EMC1813, EMC1814,
EMC1815 and EMC1833 temperature sensor chips from microchip. Does not
currently support the alert outputs.

Signed-off-by: Mark Tomlinson <mark.tomlinson@xxxxxxxxxxxxxxxxxxx>
Co-developed-by: Mathew McBride <matt@xxxxxxxxxxxxxxx>
Signed-off-by: Mathew McBride <matt@xxxxxxxxxxxxxxx>
---
 drivers/hwmon/Kconfig   |  10 ++
 drivers/hwmon/Makefile  |   1 +
 drivers/hwmon/emc181x.c | 296 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 307 insertions(+)
 create mode 100644 drivers/hwmon/emc181x.c

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 307477b8a371..196d91494536 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1820,6 +1820,16 @@ config SENSORS_EMC1403
 	  Threshold values can be configured using sysfs.
 	  Data from the different diodes are accessible via sysfs.
 
+config SENSORS_EMC181X
+	tristate "SMSC EMC181X thermal sensor"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  If you say yes here you get support for the SMSC EMC181X
+	  temperature monitoring chip.
+
+	  Data from the different diodes are accessible via sysfs.
+
 config SENSORS_EMC2103
 	tristate "SMSC EMC2103"
 	depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 3f4b0fda0998..bcea887dfe17 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -69,6 +69,7 @@ obj-$(CONFIG_SENSORS_DRIVETEMP)	+= drivetemp.o
 obj-$(CONFIG_SENSORS_DS620)	+= ds620.o
 obj-$(CONFIG_SENSORS_DS1621)	+= ds1621.o
 obj-$(CONFIG_SENSORS_EMC1403)	+= emc1403.o
+obj-$(CONFIG_SENSORS_EMC181X)	+= emc181x.o
 obj-$(CONFIG_SENSORS_EMC2103)	+= emc2103.o
 obj-$(CONFIG_SENSORS_EMC2305)	+= emc2305.o
 obj-$(CONFIG_SENSORS_EMC6W201)	+= emc6w201.o
diff --git a/drivers/hwmon/emc181x.c b/drivers/hwmon/emc181x.c
new file mode 100644
index 000000000000..364d2bfb15ca
--- /dev/null
+++ b/drivers/hwmon/emc181x.c
@@ -0,0 +1,296 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for the Microchip/SMSC EMC181x Temperature monitor
+ *
+ * Copyright (C) 2018-2019 Traverse Technologies
+ * Author: Mathew McBride <matt@xxxxxxxxxxxxxxx>
+ *
+ * Copyright (C) 2023 Allied Telesis Labs
+ * Author: Mark Tomlinson <mark.tomlinson@xxxxxxxxxxxxxxxxxxx>
+ *
+ */
+
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/of_device.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#define EMC1812_ID	0x81
+#define EMC1813_ID	0x87
+#define EMC1814_ID	0x84
+#define EMC1815_ID	0x85
+#define EMC1833_ID	0x83
+
+#define MICROCHIP_ID	0x54
+
+#define EMC181X_STATUS_REG	0x02
+#define EMC181X_CONFIG_REG	0x03
+#define EMC181X_DIODE_DATA_BASE	0x60
+#define EMC181X_PID_REG		0xfd
+#define EMC181X_SMSC_ID_REG	0xfe
+#define EMC181X_REVISION_REG	0xff
+
+/* Adjustable address type is 0x7c, 0x5c, 0x4c, 0x6c, 0x1c, 0x3c */
+/* Fixed address is either 0x4c or 0x45 */
+static const unsigned short emc181x_address_list[] = {
+	0x7c, 0x5c, 0x4c, 0x6c, 0x1c, 0x3c, 0x45, I2C_CLIENT_END
+};
+
+enum chips {
+	emc1812, emc1813,
+	emc1814, emc1815,
+	emc1833,
+};
+
+struct emc181x_data {
+	struct i2c_client *i2c;
+	enum chips type;
+	bool is_extended_range;
+};
+
+static int emc181x_read(struct device *dev, enum hwmon_sensor_types type,
+			u32 attr, int channel, long *val)
+{
+	struct emc181x_data *data = dev_get_drvdata(dev);
+	struct i2c_client *i2c = data->i2c;
+
+	u8 channel_reg = 0;
+	s32 channel_deg = 0;
+	s32 channel_frac = 0;
+
+	if (type != hwmon_temp)
+		return -EOPNOTSUPP;
+	if (channel > 4)
+		return -EINVAL;
+
+	channel_reg = EMC181X_DIODE_DATA_BASE + (channel * 0x02);
+	channel_deg = i2c_smbus_read_byte_data(i2c, channel_reg);
+	if (channel_deg < 0)
+		return channel_deg;
+	if (data->is_extended_range)
+		channel_deg -= 64;
+
+	channel_frac = i2c_smbus_read_byte_data(i2c, channel_reg + 0x01);
+	if (channel_frac < 0)
+		return channel_frac;
+
+	*val = ((channel_deg << 3) | (channel_frac >> 5)) * 125;
+	return 0;
+}
+
+static umode_t emc181x_is_visible(const void *drvdata, enum hwmon_sensor_types type,
+				  u32 attr, int channel)
+{
+	if (type == hwmon_temp && attr == hwmon_temp_input)
+		return 0444;
+	else
+		return 0;
+}
+
+static const struct hwmon_channel_info *emc1812_info[] = {
+	HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
+	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT, HWMON_T_INPUT),
+	NULL
+};
+
+static const struct hwmon_channel_info *emc1813_info[] = {
+	HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
+	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT, HWMON_T_INPUT, HWMON_T_INPUT),
+	NULL
+};
+
+static const struct hwmon_channel_info *emc1814_info[] = {
+	HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
+	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT, HWMON_T_INPUT, HWMON_T_INPUT,
+			   HWMON_T_INPUT),
+	NULL
+};
+
+static const struct hwmon_channel_info *emc1815_info[] = {
+	HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
+	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT, HWMON_T_INPUT, HWMON_T_INPUT,
+			   HWMON_T_INPUT, HWMON_T_INPUT),
+	NULL
+};
+
+static const struct hwmon_ops emc181x_ops = {
+	.is_visible = emc181x_is_visible,
+	.read = emc181x_read,
+};
+
+static const struct hwmon_chip_info emc181x_chip_info[] = {
+	[emc1812] = {
+		.ops = &emc181x_ops,
+		.info = emc1812_info,
+	},
+	[emc1813] = {
+		.ops = &emc181x_ops,
+		.info = emc1813_info,
+	},
+	[emc1814] = {
+		.ops = &emc181x_ops,
+		.info = emc1814_info,
+	},
+	[emc1815] = {
+		.ops = &emc181x_ops,
+		.info = emc1815_info,
+	},
+	[emc1833] = {
+		.ops = &emc181x_ops,
+		.info = emc1813_info,
+	},
+};
+
+static const struct i2c_device_id emc181x_i2c_id[] = {
+	{ "emc1812", emc1812 },
+	{ "emc1813", emc1813 },
+	{ "emc1814", emc1814 },
+	{ "emc1815", emc1815 },
+	{ "emc1833", emc1833 },
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, emc181x_i2c_id);
+
+/* Return 0 if detection is successful, -ENODEV otherwise */
+static int emc181x_i2c_detect(struct i2c_client *client,
+		       struct i2c_board_info *info)
+{
+	struct i2c_adapter *adapter = client->adapter;
+	int pid, id, rev;
+	const char *name;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
+				     I2C_FUNC_SMBUS_WORD_DATA))
+		return -ENODEV;
+
+	/* Determine the chip type */
+	id = i2c_smbus_read_byte_data(client, EMC181X_SMSC_ID_REG);
+	if (id < 0)
+		return id;
+	if (id != MICROCHIP_ID)
+		return -ENODEV;
+	pid = i2c_smbus_read_byte_data(client, EMC181X_PID_REG);
+	if (pid < 0)
+		return pid;
+	rev = i2c_smbus_read_byte_data(client, EMC181X_REVISION_REG);
+	if (rev < 0)
+		return rev;
+
+	switch (pid) {
+	case EMC1812_ID:
+		name = emc181x_i2c_id[emc1812].name;
+		break;
+	case EMC1813_ID:
+		name = emc181x_i2c_id[emc1813].name;
+		break;
+	case EMC1814_ID:
+		name = emc181x_i2c_id[emc1814].name;
+		break;
+	case EMC1815_ID:
+		name = emc181x_i2c_id[emc1815].name;
+		break;
+	case EMC1833_ID:
+		name = emc181x_i2c_id[emc1833].name;
+		break;
+	default:
+		return -ENODEV;
+	}
+	strscpy(info->type, name, I2C_NAME_SIZE);
+
+	dev_dbg(&client->dev,
+		"Detected device %s at 0x%02x with COMPANY: 0x%02x and PID: 0x%02x REV: 0x%02x\n",
+		name, client->addr, id, pid, rev);
+
+	return 0;
+}
+
+static int emc181x_i2c_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct device *hwmon_dev;
+	struct emc181x_data *data;
+	s32 regval;
+	u8 config;
+
+	data = devm_kzalloc(dev, sizeof(struct emc181x_data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->i2c = client;
+	if (dev_fwnode(dev)) {
+		data->type = (enum chips)device_get_match_data(dev);
+		data->is_extended_range = device_property_present(dev, "emc181x,extended-range");
+	} else
+		data->type = i2c_match_id(emc181x_i2c_id, client)->driver_data;
+
+	regval = i2c_smbus_read_byte_data(client, EMC181X_CONFIG_REG);
+	if (regval < 0) {
+		dev_dbg(dev, "Failed to read config reg %d", regval);
+		return regval;
+	}
+
+	/* By default, extended range is disabled in the EMC181X,
+	 * if enabled we need to set this in the CONFIG register.
+	 */
+	config = regval & ~0x04;
+	if (data->is_extended_range)
+		config |= 0x04;
+
+	dev_dbg(dev, "EMC181X setting CONFIG to %d\n", config);
+	if (config != regval)
+		i2c_smbus_write_byte_data(client, EMC181X_CONFIG_REG, config);
+
+	hwmon_dev = devm_hwmon_device_register_with_info(dev,
+			client->name,
+			data,
+			&emc181x_chip_info[data->type],
+			NULL);
+
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct of_device_id __maybe_unused emc181x_of_match[] = {
+	{
+		.compatible = "microchip,emc1812",
+		.data = (void *)emc1812
+	},
+	{
+		.compatible = "microchip,emc1813",
+		.data = (void *)emc1813
+	},
+	{
+		.compatible = "microchip,emc1814",
+		.data = (void *)emc1814
+	},
+	{
+		.compatible = "microchip,emc1815",
+		.data = (void *)emc1815
+	},
+	{
+		.compatible = "microchip,emc1833",
+		.data = (void *)emc1833
+	},
+	{ },
+};
+MODULE_DEVICE_TABLE(of, emc181x_of_match);
+
+static struct i2c_driver emc181x_i2c_driver = {
+	.driver = {
+		.name = "emc181x",
+		.of_match_table = of_match_ptr(emc181x_of_match),
+	},
+	.probe = emc181x_i2c_probe,
+	.id_table = emc181x_i2c_id,
+	.detect = emc181x_i2c_detect,
+	.address_list = emc181x_address_list,
+};
+
+module_i2c_driver(emc181x_i2c_driver);
+
+MODULE_DESCRIPTION("EMC181X Sensor Driver");
+MODULE_AUTHOR("Mark Tomlinson <mark.tomlinson@xxxxxxxxxxxxxxxxxxx>");
+MODULE_LICENSE("GPL");
-- 
2.41.0