On 7/28/21 7:11 AM, Balac, Arun Saravanan wrote:
From: Arun Saravanan Balachandran <Arun_Saravanan_Balac@xxxxxxxx>
Add hardware monitoring driver for Maxim MAX6620 Fan controller
Originally-from: L. Grunenberg <contact@xxxxxxxxxxxxxx>
Originally-from: Cumulus Networks <support@xxxxxxxxxxxxxxxxxxx>
Originally-from: Shuotian Cheng <shuche@xxxxxxxxxxxxx>
Signed-off-by: Arun Saravanan Balachandran <Arun_Saravanan_Balac@xxxxxxxx>
---
drivers/hwmon/Kconfig | 10 +
drivers/hwmon/Makefile | 1 +
drivers/hwmon/max6620.c | 464 ++++++++++++++++++++++++++++++++++++++++
Documentation missing.
3 files changed, 475 insertions(+)
create mode 100644 drivers/hwmon/max6620.c
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index e3675377bc5d..7bb2fbd72db4 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1022,6 +1022,16 @@ config SENSORS_MAX31730
This driver can also be built as a module. If so, the module
will be called max31730.
+config SENSORS_MAX6620
+ tristate "Maxim MAX6620 sensor chip"
+ depends on I2C
+ help
+ If you say yes here you get support for the MAX6620
+ sensor chips.
This is not a sensor, it is a fan controller.
+
+ This driver can also be built as a module. If so, the module
+ will be called max6620.
+
config SENSORS_MAX6621
tristate "Maxim MAX6621 sensor chip"
depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index d712c61c1f5e..9e50ff903931 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -135,6 +135,7 @@ obj-$(CONFIG_SENSORS_MAX1668) += max1668.o
obj-$(CONFIG_SENSORS_MAX197) += max197.o
obj-$(CONFIG_SENSORS_MAX31722) += max31722.o
obj-$(CONFIG_SENSORS_MAX31730) += max31730.o
+obj-$(CONFIG_SENSORS_MAX6620) += max6620.o
obj-$(CONFIG_SENSORS_MAX6621) += max6621.o
obj-$(CONFIG_SENSORS_MAX6639) += max6639.o
obj-$(CONFIG_SENSORS_MAX6642) += max6642.o
diff --git a/drivers/hwmon/max6620.c b/drivers/hwmon/max6620.c
new file mode 100644
index 000000000000..05f6fdc80343
--- /dev/null
+++ b/drivers/hwmon/max6620.c
@@ -0,0 +1,464 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * max6620.c - Linux Kernel module for hardware monitoring.
Pointless.
+ *
+ * (C) 2012 by L. Grunenberg <contact@xxxxxxxxxxxxxx>
+ *
+ * based on code written by :
+ * 2007 by Hans J. Koch <hjk@xxxxxxxxxxxx>
+ * John Morris <john.morris@xxxxxxxxxxxxxx>
+ * Copyright (c) 2003 Spirent Communications
+ * and Claus Gindhart <claus.gindhart@xxxxxxxxxxx>
+ *
+ * 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/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/jiffies.h>
+#include <linux/i2c.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
Not needed.
+#include <linux/err.h>
Alphabetic include file order, please.
+
+
+/*
+ * 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 0x80
+#define MAX6620_CFG_POR 0x40
+#define MAX6620_CFG_TIMEOUT 0x20
+#define MAX6620_CFG_FULLFAN 0x10
+#define MAX6620_CFG_OSC 0x08
+#define MAX6620_CFG_WD_MASK 0x06
+#define MAX6620_CFG_WD_2 0x02
+#define MAX6620_CFG_WD_6 0x04
+#define MAX6620_CFG_WD10 0x06
+#define MAX6620_CFG_WD 0x01
Please use BIT().
+
+
+/*
+ * Failure status register bits
+ */
+
+#define MAX6620_FAIL_TACH0 0x10
+#define MAX6620_FAIL_TACH1 0x20
+#define MAX6620_FAIL_TACH2 0x40
+#define MAX6620_FAIL_TACH3 0x80
+#define MAX6620_FAIL_MASK0 0x01
+#define MAX6620_FAIL_MASK1 0x02
+#define MAX6620_FAIL_MASK2 0x04
+#define MAX6620_FAIL_MASK3 0x08
+
+
+/* Minimum and maximum values of the FAN-RPM */
+#define FAN_RPM_MIN 240
+#define FAN_RPM_MAX 30000
#define<space>DEFINE<tab>value
+
+/*
+ * Insmod parameters
+ */
+
+
+/* clock: The clock frequency of the chip the driver should assume */
+static int clock = 8192;
+static u32 np = 2;
'clock' is always 8192. np is the number of pulses per revolution,
and always 2. Please use defines for both.
+
+module_param(clock, int, 0444);
+
+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;
+ char valid; /* zero until following fields are valid */
bool. However, I would strongly suggest to drop caching
except for the fault register.
+ unsigned long last_updated; /* in jiffies */
+
+ /* register values */
+ u8 config;
+ u8 fancfg[4];
+ u8 fandyn[4];
+ u8 fault;
+ u16 tach[4];
+ u16 target[4];
+};
+
+static u8 max6620_fan_div_from_reg(u8 val)
+{
+ return 1 << ((val & 0xE0) >> 5);
+}
+
+static struct max6620_data *max6620_update_device(struct device *dev)
+{
+ struct max6620_data *data = dev_get_drvdata(dev);
+ struct i2c_client *client = data->client;
+ int i;
+ u8 fault_reg, regval1, regval2;
+
+ mutex_lock(&data->update_lock);
+
+ if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
+
+ for (i = 0; i < 4; i++) {
+ data->fancfg[i] = i2c_smbus_read_byte_data(client, config_reg[i]);
+ data->fandyn[i] = i2c_smbus_read_byte_data(client, dyn_reg[i]);
+ regval1 = i2c_smbus_read_byte_data(client, tach_reg[i]);
+ regval2 = i2c_smbus_read_byte_data(client, tach_reg[i] + 1);
+ data->tach[i] = ((regval1 << 3) & 0x7f8) | ((regval2 >> 5) & 0x7);
+ regval1 = i2c_smbus_read_byte_data(client, target_reg[i]);
+ regval2 = i2c_smbus_read_byte_data(client, target_reg[i] + 1);
+ data->target[i] = ((regval1 << 3) & 0x7f8) | ((regval2 >> 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.
+ */
+ fault_reg = i2c_smbus_read_byte_data(client, MAX6620_REG_FAULT);
+ data->fault |= (fault_reg >> 4) & (fault_reg & 0x0F);
+
+ data->last_updated = jiffies;
+ data->valid = 1;
+ }
+
+ mutex_unlock(&data->update_lock);
+
+ return data;
+}
+
+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;
+ }
+
+ 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 = max6620_update_device(dev);
+ int alarm = 0;
+ u8 div;
+
+ switch (type) {
+ case hwmon_fan:
+ switch (attr) {
+ case hwmon_fan_alarm:
+ mutex_lock(&data->update_lock);
+ if (data->fault & (1 << channel))
+ alarm = 1;
+
+ mutex_unlock(&data->update_lock);
Locking is pointless here.
*val = !!(data->fault & BIT(channel));
does the same.
This code does not clear alarms after reading the attribute,
or re-enable alarms. Clearing faults by relying on a write
to fan_target is not appropriate. Alarms should be cleared
and re-armed after reading an alarm attribute.
+ *val = alarm;
+
+ 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 {
if and else branch both need to use { }.
Please run checkpatch --strict and fix what it reports.
+ div = max6620_fan_div_from_reg(data->fandyn[channel]);
+ *val = (60 * div * clock)/(data->tach[channel] * np);
+ }
+ break;
+ case hwmon_fan_target:
+ if (data->target[channel] == 0)
+ *val = 0;
+ else {
+ div = max6620_fan_div_from_reg(data->fandyn[channel]);
+ *val = (60 * div * clock)/(data->target[channel] * np);
+ }
+ 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 = dev_get_drvdata(dev);
+ struct i2c_client *client = data->client;
+ u8 div;
+ u16 tach;
+ u8 val1;
+ u8 val2;
+
+ switch (type) {
+ case hwmon_fan:
+ switch (attr) {
+ case hwmon_fan_div:
+ mutex_lock(&data->update_lock);
The lock is pointless here. Move it after the switch statement to
simplify the code.
+ 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:
+ mutex_unlock(&data->update_lock);
+ return -EINVAL;
+ }
+ data->fandyn[channel] &= 0x1F;
+ data->fandyn[channel] |= div << 5;
+ i2c_smbus_write_byte_data(client, dyn_reg[channel],
+ data->fandyn[channel]);
Please do not ignore errors (everywhere).
+ mutex_unlock(&data->update_lock);
+
+ break;
+ case hwmon_fan_target:
+ val = clamp_val(val, FAN_RPM_MIN, FAN_RPM_MAX);
+ mutex_lock(&data->update_lock);
+
+ div = max6620_fan_div_from_reg(data->fandyn[channel]);
+ tach = (60 * div * clock)/(val * np);
+ val1 = (tach >> 3) & 0xff;
+ val2 = (tach << 5) & 0xe0;
+ i2c_smbus_write_byte_data(client, target_reg[channel], val1);
+ i2c_smbus_write_byte_data(client, target_reg[channel] + 1, val2);
+
+ /* Setting TACH count re-enables fan fault detection */
+ data->fault &= ~(1 << channel);
Maybe, but expecting the user to write to this register to re-arm alarms
is not appropriate.
+
+ mutex_unlock(&data->update_lock);
+
+ break;
+ default:
+ return -EOPNOTSUPP;
+ }
+ break;
+
+ default:
+ return -EOPNOTSUPP;
+ }
+
+ return 0;
+}
+
+static const u32 max6620_fan_config[] = {
+ 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,
+ 0
+};
+
+static const struct hwmon_channel_info max6620_fan = {
+ .type = hwmon_fan,
+ .config = max6620_fan_config,
+};
+
+static const struct hwmon_channel_info *max6620_info[] = {
+ &max6620_fan,
+ NULL
+};
Please use the HWMON_CHANNEL_INFO() macro.
+
+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 i2c_client *client)
+{
+ struct max6620_data *data = i2c_get_clientdata(client);
+ int config;
+ int err = -EIO;
+ int i;
+
+ config = i2c_smbus_read_byte_data(client, MAX6620_REG_CONFIG);
+
Unnecessary empty line
+ if (config < 0) {
+ dev_err(&client->dev, "Error reading config, aborting.\n");
+ return err;
Please do not overwrite error codes. This should return config.
+ }
+
+ /*
+ * Set bit 4, disable other fans from going full speed on a fail
+ * failure.
+ */
+ if (i2c_smbus_write_byte_data(client, MAX6620_REG_CONFIG, config | 0x10)) {
+ dev_err(&client->dev, "Config write error, aborting.\n");
+ return err;
Please return the error code from i2c_smbus_write_byte_data().
+ }
+
+ data->config = config;
data->config is not used anywhere.
+ for (i = 0; i < 4; i++) {
+ data->fancfg[i] = i2c_smbus_read_byte_data(client, config_reg[i]);
+ /* Enable RPM mode */
+ data->fancfg[i] |= 0xa8;
+ i2c_smbus_write_byte_data(client, config_reg[i], data->fancfg[i]);
+ data->fandyn[i] = i2c_smbus_read_byte_data(client, dyn_reg[i]);
+ /* 2 counts (001) and Rate change 100 (0.125 secs) */
+ data->fandyn[i] = 0x30;
+ i2c_smbus_write_byte_data(client, dyn_reg[i], data->fandyn[i]);
Again, please do not ignore error codes. Also, this mostly duplicates
max6620_update_device().
+ }
+ 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;
+
+ i2c_set_clientdata(client, data);
The only reason for this is to use it in max6620_init_client().
Just pass 'data' to that function instead.
+ data->client = client;
+ mutex_init(&data->update_lock);
+
+ /*
+ * Initialize the max6620 chip
+ */
Pointless comment.
+ err = max6620_init_client(client);
+ 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");
base-commit: ff1176468d368232b684f75e82563369208bc371
