hwmon: Add Maxim MAX6620 hardware monitoring driver

Add hardware monitoring driver for Maxim MAX6620 Fan controller

Originally-from: L. Grunenberg <contact@lgrunenberg.de>
Originally-from: Cumulus Networks <support@cumulusnetworks.com>
Originally-from: Shuotian Cheng <shuche@microsoft.com>
Signed-off-by: Arun Saravanan Balachandran <Arun_Saravanan_Balac@dell.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 514 insertions, 0 deletions

diff --git a/drivers/hwmon/max6620.c b/drivers/hwmon/max6620.c
new file mode 100644
index 000000000000..202b6438179d
--- /dev/null
+++ b/drivers/hwmon/max6620.c
@@ -0,0 +1,514 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Hardware monitoring driver for Maxim MAX6620
+ *
+ * Originally from L. Grunenberg.
+ * (C) 2012 by L. Grunenberg <contact@lgrunenberg.de>
+ *
+ * Copyright (c) 2021 Dell Inc. or its subsidiaries. All Rights Reserved.
+ *
+ * based on code written by :
+ * 2007 by Hans J. Koch <hjk@hansjkoch.de>
+ * John Morris <john.morris@spirentcom.com>
+ * Copyright (c) 2003 Spirent Communications
+ * and Claus Gindhart <claus.gindhart@kontron.com>
+ *
+ * This module has only been tested with the MAX6620 chip.
+ *
+ * The datasheet was last seen at:
+ *
+ *        http://pdfserv.maxim-ic.com/en/ds/MAX6620.pdf
+ *
+ */
+
+#include <linux/bits.h>
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+/*
+ * MAX 6620 registers
+ */
+
+#define MAX6620_REG_CONFIG	0x00
+#define MAX6620_REG_FAULT	0x01
+#define MAX6620_REG_CONF_FAN0	0x02
+#define MAX6620_REG_CONF_FAN1	0x03
+#define MAX6620_REG_CONF_FAN2	0x04
+#define MAX6620_REG_CONF_FAN3	0x05
+#define MAX6620_REG_DYN_FAN0	0x06
+#define MAX6620_REG_DYN_FAN1	0x07
+#define MAX6620_REG_DYN_FAN2	0x08
+#define MAX6620_REG_DYN_FAN3	0x09
+#define MAX6620_REG_TACH0	0x10
+#define MAX6620_REG_TACH1	0x12
+#define MAX6620_REG_TACH2	0x14
+#define MAX6620_REG_TACH3	0x16
+#define MAX6620_REG_VOLT0	0x18
+#define MAX6620_REG_VOLT1	0x1A
+#define MAX6620_REG_VOLT2	0x1C
+#define MAX6620_REG_VOLT3	0x1E
+#define MAX6620_REG_TAR0	0x20
+#define MAX6620_REG_TAR1	0x22
+#define MAX6620_REG_TAR2	0x24
+#define MAX6620_REG_TAR3	0x26
+#define MAX6620_REG_DAC0	0x28
+#define MAX6620_REG_DAC1	0x2A
+#define MAX6620_REG_DAC2	0x2C
+#define MAX6620_REG_DAC3	0x2E
+
+/*
+ * Config register bits
+ */
+
+#define MAX6620_CFG_RUN		BIT(7)
+#define MAX6620_CFG_POR		BIT(6)
+#define MAX6620_CFG_TIMEOUT	BIT(5)
+#define MAX6620_CFG_FULLFAN	BIT(4)
+#define MAX6620_CFG_OSC		BIT(3)
+#define MAX6620_CFG_WD_MASK	(BIT(2) | BIT(1))
+#define MAX6620_CFG_WD_2	BIT(1)
+#define MAX6620_CFG_WD_6	BIT(2)
+#define MAX6620_CFG_WD10	(BIT(2) | BIT(1))
+#define MAX6620_CFG_WD		BIT(0)
+
+/*
+ * Failure status register bits
+ */
+
+#define MAX6620_FAIL_TACH0	BIT(4)
+#define MAX6620_FAIL_TACH1	BIT(5)
+#define MAX6620_FAIL_TACH2	BIT(6)
+#define MAX6620_FAIL_TACH3	BIT(7)
+#define MAX6620_FAIL_MASK0	BIT(0)
+#define MAX6620_FAIL_MASK1	BIT(1)
+#define MAX6620_FAIL_MASK2	BIT(2)
+#define MAX6620_FAIL_MASK3	BIT(3)
+
+#define MAX6620_CLOCK_FREQ	8192 /* Clock frequency in Hz */
+#define MAX6620_PULSE_PER_REV	2 /* Tachometer pulses per revolution */
+
+/* Minimum and maximum values of the FAN-RPM */
+#define FAN_RPM_MIN	240
+#define FAN_RPM_MAX	30000
+
+static const u8 config_reg[] = {
+	MAX6620_REG_CONF_FAN0,
+	MAX6620_REG_CONF_FAN1,
+	MAX6620_REG_CONF_FAN2,
+	MAX6620_REG_CONF_FAN3,
+};
+
+static const u8 dyn_reg[] = {
+	MAX6620_REG_DYN_FAN0,
+	MAX6620_REG_DYN_FAN1,
+	MAX6620_REG_DYN_FAN2,
+	MAX6620_REG_DYN_FAN3,
+};
+
+static const u8 tach_reg[] = {
+	MAX6620_REG_TACH0,
+	MAX6620_REG_TACH1,
+	MAX6620_REG_TACH2,
+	MAX6620_REG_TACH3,
+};
+
+static const u8 target_reg[] = {
+	MAX6620_REG_TAR0,
+	MAX6620_REG_TAR1,
+	MAX6620_REG_TAR2,
+	MAX6620_REG_TAR3,
+};
+
+/*
+ * Client data (each client gets its own)
+ */
+
+struct max6620_data {
+	struct i2c_client *client;
+	struct mutex update_lock;
+	bool valid; /* false until following fields are valid */
+	unsigned long last_updated; /* in jiffies */
+
+	/* register values */
+	u8 fancfg[4];
+	u8 fandyn[4];
+	u8 fault;
+	u16 tach[4];
+	u16 target[4];
+};
+
+static u8 max6620_fan_div_from_reg(u8 val)
+{
+	return BIT((val & 0xE0) >> 5);
+}
+
+static u16 max6620_fan_rpm_to_tach(u8 div, int rpm)
+{
+	return (60 * div * MAX6620_CLOCK_FREQ) / (rpm * MAX6620_PULSE_PER_REV);
+}
+
+static int max6620_fan_tach_to_rpm(u8 div, u16 tach)
+{
+	return (60 * div * MAX6620_CLOCK_FREQ) / (tach * MAX6620_PULSE_PER_REV);
+}
+
+static int max6620_update_device(struct device *dev)
+{
+	struct max6620_data *data = dev_get_drvdata(dev);
+	struct i2c_client *client = data->client;
+	int i;
+	int ret = 0;
+
+	mutex_lock(&data->update_lock);
+
+	if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
+		for (i = 0; i < 4; i++) {
+			ret = i2c_smbus_read_byte_data(client, config_reg[i]);
+			if (ret < 0)
+				goto error;
+			data->fancfg[i] = ret;
+
+			ret = i2c_smbus_read_byte_data(client, dyn_reg[i]);
+			if (ret < 0)
+				goto error;
+			data->fandyn[i] = ret;
+
+			ret = i2c_smbus_read_byte_data(client, tach_reg[i]);
+			if (ret < 0)
+				goto error;
+			data->tach[i] = (ret << 3) & 0x7f8;
+			ret = i2c_smbus_read_byte_data(client, tach_reg[i] + 1);
+			if (ret < 0)
+				goto error;
+			data->tach[i] |= (ret >> 5) & 0x7;
+
+			ret = i2c_smbus_read_byte_data(client, target_reg[i]);
+			if (ret < 0)
+				goto error;
+			data->target[i] = (ret << 3) & 0x7f8;
+			ret = i2c_smbus_read_byte_data(client, target_reg[i] + 1);
+			if (ret < 0)
+				goto error;
+			data->target[i] |= (ret >> 5) & 0x7;
+		}
+
+		/*
+		 * Alarms are cleared on read in case the condition that
+		 * caused the alarm is removed. Keep the value latched here
+		 * for providing the register through different alarm files.
+		 */
+		ret = i2c_smbus_read_byte_data(client, MAX6620_REG_FAULT);
+		if (ret < 0)
+			goto error;
+		data->fault |= (ret >> 4) & (ret & 0x0F);
+
+		data->last_updated = jiffies;
+		data->valid = true;
+	}
+
+error:
+	mutex_unlock(&data->update_lock);
+	return ret;
+}
+
+static umode_t
+max6620_is_visible(const void *data, enum hwmon_sensor_types type, u32 attr,
+		   int channel)
+{
+	switch (type) {
+	case hwmon_fan:
+		switch (attr) {
+		case hwmon_fan_alarm:
+		case hwmon_fan_input:
+			return 0444;
+		case hwmon_fan_div:
+		case hwmon_fan_target:
+			return 0644;
+		default:
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+static int
+max6620_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
+	     int channel, long *val)
+{
+	struct max6620_data *data;
+	struct i2c_client *client;
+	int ret;
+	u8 div;
+	u8 val1;
+	u8 val2;
+
+	ret = max6620_update_device(dev);
+	if (ret < 0)
+		return ret;
+	data = dev_get_drvdata(dev);
+	client = data->client;
+
+	switch (type) {
+	case hwmon_fan:
+		switch (attr) {
+		case hwmon_fan_alarm:
+			mutex_lock(&data->update_lock);
+			*val = !!(data->fault & BIT(channel));
+
+			/* Setting TACH count to re-enable fan fault detection */
+			if (*val == 1) {
+				val1 = (data->target[channel] >> 3) & 0xff;
+				val2 = (data->target[channel] << 5) & 0xe0;
+				ret = i2c_smbus_write_byte_data(client,
+								target_reg[channel], val1);
+				if (ret < 0) {
+					mutex_unlock(&data->update_lock);
+					return ret;
+				}
+				ret = i2c_smbus_write_byte_data(client,
+								target_reg[channel] + 1, val2);
+				if (ret < 0) {
+					mutex_unlock(&data->update_lock);
+					return ret;
+				}
+
+				data->fault &= ~BIT(channel);
+			}
+			mutex_unlock(&data->update_lock);
+
+			break;
+		case hwmon_fan_div:
+			*val = max6620_fan_div_from_reg(data->fandyn[channel]);
+			break;
+		case hwmon_fan_input:
+			if (data->tach[channel] == 0) {
+				*val = 0;
+			} else {
+				div = max6620_fan_div_from_reg(data->fandyn[channel]);
+				*val = max6620_fan_tach_to_rpm(div, data->tach[channel]);
+			}
+			break;
+		case hwmon_fan_target:
+			if (data->target[channel] == 0) {
+				*val = 0;
+			} else {
+				div = max6620_fan_div_from_reg(data->fandyn[channel]);
+				*val = max6620_fan_tach_to_rpm(div, data->target[channel]);
+			}
+			break;
+		default:
+			return -EOPNOTSUPP;
+		}
+		break;
+
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static int
+max6620_write(struct device *dev, enum hwmon_sensor_types type, u32 attr,
+	      int channel, long val)
+{
+	struct max6620_data *data;
+	struct i2c_client *client;
+	int ret;
+	u8 div;
+	u16 tach;
+	u8 val1;
+	u8 val2;
+
+	ret = max6620_update_device(dev);
+	if (ret < 0)
+		return ret;
+	data = dev_get_drvdata(dev);
+	client = data->client;
+	mutex_lock(&data->update_lock);
+
+	switch (type) {
+	case hwmon_fan:
+		switch (attr) {
+		case hwmon_fan_div:
+			switch (val) {
+			case 1:
+				div = 0;
+				break;
+			case 2:
+				div = 1;
+				break;
+			case 4:
+				div = 2;
+				break;
+			case 8:
+				div = 3;
+				break;
+			case 16:
+				div = 4;
+				break;
+			case 32:
+				div = 5;
+				break;
+			default:
+				ret = -EINVAL;
+				goto error;
+			}
+			data->fandyn[channel] &= 0x1F;
+			data->fandyn[channel] |= div << 5;
+			ret = i2c_smbus_write_byte_data(client, dyn_reg[channel],
+							data->fandyn[channel]);
+			break;
+		case hwmon_fan_target:
+			val = clamp_val(val, FAN_RPM_MIN, FAN_RPM_MAX);
+			div = max6620_fan_div_from_reg(data->fandyn[channel]);
+			tach = max6620_fan_rpm_to_tach(div, val);
+			val1 = (tach >> 3) & 0xff;
+			val2 = (tach << 5) & 0xe0;
+			ret = i2c_smbus_write_byte_data(client, target_reg[channel], val1);
+			if (ret < 0)
+				break;
+			ret = i2c_smbus_write_byte_data(client, target_reg[channel] + 1, val2);
+			if (ret < 0)
+				break;
+
+			/* Setting TACH count re-enables fan fault detection */
+			data->fault &= ~BIT(channel);
+
+			break;
+		default:
+			ret = -EOPNOTSUPP;
+			break;
+		}
+		break;
+
+	default:
+		ret = -EOPNOTSUPP;
+		break;
+	}
+
+error:
+	mutex_unlock(&data->update_lock);
+	return ret;
+}
+
+static const struct hwmon_channel_info *max6620_info[] = {
+	HWMON_CHANNEL_INFO(fan,
+			   HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_TARGET | HWMON_F_ALARM,
+			   HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_TARGET | HWMON_F_ALARM,
+			   HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_TARGET | HWMON_F_ALARM,
+			   HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_TARGET | HWMON_F_ALARM),
+	NULL
+};
+
+static const struct hwmon_ops max6620_hwmon_ops = {
+	.read = max6620_read,
+	.write = max6620_write,
+	.is_visible = max6620_is_visible,
+};
+
+static const struct hwmon_chip_info max6620_chip_info = {
+	.ops = &max6620_hwmon_ops,
+	.info = max6620_info,
+};
+
+static int max6620_init_client(struct max6620_data *data)
+{
+	struct i2c_client *client = data->client;
+	int config;
+	int err;
+	int i;
+	int reg;
+
+	config = i2c_smbus_read_byte_data(client, MAX6620_REG_CONFIG);
+	if (config < 0) {
+		dev_err(&client->dev, "Error reading config, aborting.\n");
+		return config;
+	}
+
+	/*
+	 * Set bit 4, disable other fans from going full speed on a fail
+	 * failure.
+	 */
+	err = i2c_smbus_write_byte_data(client, MAX6620_REG_CONFIG, config | 0x10);
+	if (err < 0) {
+		dev_err(&client->dev, "Config write error, aborting.\n");
+		return err;
+	}
+
+	for (i = 0; i < 4; i++) {
+		reg = i2c_smbus_read_byte_data(client, config_reg[i]);
+		if (reg < 0)
+			return reg;
+		data->fancfg[i] = reg;
+
+		/* Enable RPM mode */
+		data->fancfg[i] |= 0xa8;
+		err = i2c_smbus_write_byte_data(client, config_reg[i], data->fancfg[i]);
+		if (err < 0)
+			return err;
+
+		/* 2 counts (001) and Rate change 100 (0.125 secs) */
+		data->fandyn[i] = 0x30;
+		err = i2c_smbus_write_byte_data(client, dyn_reg[i], data->fandyn[i]);
+		if (err < 0)
+			return err;
+	}
+	return 0;
+}
+
+static int max6620_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct max6620_data *data;
+	struct device *hwmon_dev;
+	int err;
+
+	data = devm_kzalloc(dev, sizeof(struct max6620_data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->client = client;
+	mutex_init(&data->update_lock);
+
+	err = max6620_init_client(data);
+	if (err)
+		return err;
+
+	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
+							 data,
+							 &max6620_chip_info,
+							 NULL);
+
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct i2c_device_id max6620_id[] = {
+	{ "max6620", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, max6620_id);
+
+static struct i2c_driver max6620_driver = {
+	.class		= I2C_CLASS_HWMON,
+	.driver = {
+		.name	= "max6620",
+	},
+	.probe_new	= max6620_probe,
+	.id_table	= max6620_id,
+};
+
+module_i2c_driver(max6620_driver);
+
+MODULE_AUTHOR("Lucas Grunenberg");
+MODULE_DESCRIPTION("MAX6620 sensor driver");
+MODULE_LICENSE("GPL");