[PATCH 1/2] hwmon: (max127) Add Maxim MAX127 hardware monitoring driver

rentao.bupt
2020-11-17T01:10:18Z

Add hardware monitoring driver for the Maxim MAX127 chip.

MAX127 min/max range handling code is inspired by the max197 driver.

Signed-off-by: Tao Ren <rentao.bupt@gmail.com>
---
drivers/hwmon/Kconfig | 9 ++
drivers/hwmon/Makefile | 1 +
drivers/hwmon/max127.c | 286 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 296 insertions(+)
create mode 100644 drivers/hwmon/max127.c

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 9d600e0c5584..716df51edc87 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -950,6 +950,15 @@ config SENSORS_MAX1111
This driver can also be built as a module. If so, the module
will be called max1111.

+config SENSORS_MAX127
+ tristate "Maxim MAX127 12-bit 8-channel Data Acquisition System"
+ depends on I2C
+ help
+ Say y here to support Maxim's MAX127 DAS chips.
+
+ This driver can also be built as a module. If so, the module
+ will be called max127.
+
config SENSORS_MAX16065
tristate "Maxim MAX16065 System Manager and compatibles"
depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 1083bbfac779..01ca5d3fbad4 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -127,6 +127,7 @@ obj-$(CONFIG_SENSORS_LTC4260) += ltc4260.o
obj-$(CONFIG_SENSORS_LTC4261) += ltc4261.o
obj-$(CONFIG_SENSORS_LTQ_CPUTEMP) += ltq-cputemp.o
obj-$(CONFIG_SENSORS_MAX1111) += max1111.o
+obj-$(CONFIG_SENSORS_MAX127) += max127.o
obj-$(CONFIG_SENSORS_MAX16065) += max16065.o
obj-$(CONFIG_SENSORS_MAX1619) += max1619.o
obj-$(CONFIG_SENSORS_MAX1668) += max1668.o
diff --git a/drivers/hwmon/max127.c b/drivers/hwmon/max127.c
new file mode 100644
index 000000000000..df74a95bcf28
--- /dev/null
+++ b/drivers/hwmon/max127.c
@@ -0,0 +1,286 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Hardware monitoring driver for MAX127.
+ *
+ * Copyright (c) 2020 Facebook Inc.
+ */
+
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/sysfs.h>
+
+/* MAX127 Control Byte. */
+#define MAX127_CTRL_START BIT(7)
+#define MAX127_CTRL_SEL_OFFSET 4
+#define MAX127_CTRL_RNG BIT(3)
+#define MAX127_CTRL_BIP BIT(2)
+#define MAX127_CTRL_PD1 BIT(1)
+#define MAX127_CTRL_PD0 BIT(0)
+
+#define MAX127_NUM_CHANNELS 8
+#define MAX127_SET_CHANNEL(ch) (((ch) & 7) << (MAX127_CTRL_SEL_OFFSET))
+
+#define MAX127_INPUT_LIMIT 10 /* 10V */
+
+/*
+ * MAX127 returns 2 bytes at read:
+ * - the first byte contains data[11:4].
+ * - the second byte contains data[3:0] (MSB) and 4 dummy 0s (LSB).
+ */
+#define MAX127_DATA1_SHIFT 4
+
+struct max127_data {
+ struct mutex lock;
+ struct i2c_client *client;
+ int input_limit;
+ u8 ctrl_byte[MAX127_NUM_CHANNELS];
+};
+
+static int max127_select_channel(struct max127_data *data, int channel)
+{
+ int status;
+ struct i2c_client *client = data->client;
+ struct i2c_msg msg = {
+ .addr = client->addr,
+ .flags = 0,
+ .len = 1,
+ .buf = &data->ctrl_byte[channel],
+ };
+
+ status = i2c_transfer(client->adapter, &msg, 1);
+ if (status != 1)
+ return status;
+
+ return 0;
+}
+
+static int max127_read_channel(struct max127_data *data, int channel, u16 *vin)
+{
+ int status;
+ u8 i2c_data[2];
+ struct i2c_client *client = data->client;
+ struct i2c_msg msg = {
+ .addr = client->addr,
+ .flags = I2C_M_RD,
+ .len = 2,
+ .buf = i2c_data,
+ };
+
+ status = i2c_transfer(client->adapter, &msg, 1);
+ if (status != 1)
+ return status;
+
+ *vin = ((i2c_data[0] << 8) | i2c_data[1]) >> MAX127_DATA1_SHIFT;
+ return 0;
+}
+
+static ssize_t max127_input_show(struct device *dev,
+ struct device_attribute *dev_attr,
+ char *buf)
+{
+ u16 vin;
+ int status;
+ struct max127_data *data = dev_get_drvdata(dev);
+ struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
+
+ if (mutex_lock_interruptible(&data->lock))
+ return -ERESTARTSYS;
+
+ status = max127_select_channel(data, attr->index);
+ if (status)
+ goto exit;
+
+ status = max127_read_channel(data, attr->index, &vin);
+ if (status)
+ goto exit;
+
+ status = sprintf(buf, "%u", vin);
+
+exit:
+ mutex_unlock(&data->lock);
+ return status;
+}
+
+static ssize_t max127_range_show(struct device *dev,
+ struct device_attribute *dev_attr,
+ char *buf)
+{
+ u8 ctrl, rng_bip;
+ struct max127_data *data = dev_get_drvdata(dev);
+ struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(dev_attr);
+ int rng_type = attr->nr; /* 0 for min, 1 for max */
+ int channel = attr->index;
+ int full = data->input_limit;
+ int half = full / 2;
+ int range_table[4][2] = {
+ [0] = {0, half}, /* RNG=0, BIP=0 */
+ [1] = {-half, half}, /* RNG=0, BIP=1 */
+ [2] = {0, full}, /* RNG=1, BIP=0 */
+ [3] = {-full, full}, /* RNG=1, BIP=1 */
+ };
+
+ if (mutex_lock_interruptible(&data->lock))
+ return -ERESTARTSYS;
+ ctrl = data->ctrl_byte[channel];
+ mutex_unlock(&data->lock);
+
+ rng_bip = (ctrl >> 2) & 3;
+ return sprintf(buf, "%d", range_table[rng_bip][rng_type]);
+}
+
+static void max127_set_range(struct max127_data *data, int channel)
+{
+ data->ctrl_byte[channel] |= MAX127_CTRL_RNG;
+}
+
+static void max127_clear_range(struct max127_data *data, int channel)
+{
+ data->ctrl_byte[channel] &= ~MAX127_CTRL_RNG;
+}
+
+static void max127_set_polarity(struct max127_data *data, int channel)
+{
+ data->ctrl_byte[channel] |= MAX127_CTRL_BIP;
+}
+
+static void max127_clear_polarity(struct max127_data *data, int channel)
+{
+ data->ctrl_byte[channel] &= ~MAX127_CTRL_BIP;
+}
+
+static ssize_t max127_range_store(struct device *dev,
+ struct device_attribute *devattr,
+ const char *buf,
+ size_t count)
+{
+ struct max127_data *data = dev_get_drvdata(dev);
+ struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(devattr);
+ int rng_type = attr->nr; /* 0 for min, 1 for max */
+ int channel = attr->index;
+ int full = data->input_limit;
+ int half = full / 2;
+ long input, output;
+
+ if (kstrtol(buf, 0, &input))
+ return -EINVAL;
+
+ if (rng_type == 0) { /* min input */
+ if (input <= -full)
+ output = -full;
+ else if (input < 0)
+ output = -half;
+ else
+ output = 0;
+ } else { /* max input */
+ output = (input >= full) ? full : half;
+ }
+
+ if (mutex_lock_interruptible(&data->lock))
+ return -ERESTARTSYS;
+
+ if (output == -full) {
+ max127_set_polarity(data, channel);
+ max127_set_range(data, channel);
+ } else if (output == -half) {
+ max127_set_polarity(data, channel);
+ max127_clear_range(data, channel);
+ } else if (output == 0) {
+ max127_clear_polarity(data, channel);
+ } else if (output == half) {
+ max127_clear_range(data, channel);
+ } else {
+ max127_set_range(data, channel);
+ }
+
+ mutex_unlock(&data->lock);
+
+ return count;
+}
+
+#define MAX127_SENSOR_DEV_ATTR_DEF(ch) \
+ static SENSOR_DEVICE_ATTR_RO(in##ch##_input, max127_input, ch); \
+ static SENSOR_DEVICE_ATTR_2_RW(in##ch##_min, max127_range, 0, ch); \
+ static SENSOR_DEVICE_ATTR_2_RW(in##ch##_max, max127_range, 1, ch)
+
+MAX127_SENSOR_DEV_ATTR_DEF(0);
+MAX127_SENSOR_DEV_ATTR_DEF(1);
+MAX127_SENSOR_DEV_ATTR_DEF(2);
+MAX127_SENSOR_DEV_ATTR_DEF(3);
+MAX127_SENSOR_DEV_ATTR_DEF(4);
+MAX127_SENSOR_DEV_ATTR_DEF(5);
+MAX127_SENSOR_DEV_ATTR_DEF(6);
+MAX127_SENSOR_DEV_ATTR_DEF(7);
+
+#define MAX127_SENSOR_DEVICE_ATTR(ch) \
+ &sensor_dev_attr_in##ch##_input.dev_attr.attr, \
+ &sensor_dev_attr_in##ch##_min.dev_attr.attr, \
+ &sensor_dev_attr_in##ch##_max.dev_attr.attr
+
+static struct attribute *max127_attrs[] = {
+ MAX127_SENSOR_DEVICE_ATTR(0),
+ MAX127_SENSOR_DEVICE_ATTR(1),
+ MAX127_SENSOR_DEVICE_ATTR(2),
+ MAX127_SENSOR_DEVICE_ATTR(3),
+ MAX127_SENSOR_DEVICE_ATTR(4),
+ MAX127_SENSOR_DEVICE_ATTR(5),
+ MAX127_SENSOR_DEVICE_ATTR(6),
+ MAX127_SENSOR_DEVICE_ATTR(7),
+ NULL,
+};
+
+ATTRIBUTE_GROUPS(max127);
+
+static const struct attribute_group max127_attr_groups = {
+ .attrs = max127_attrs,
+};
+
+static int max127_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ int i;
+ struct device *hwmon_dev;
+ struct max127_data *data;
+ struct device *dev = &client->dev;
+
+ data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ data->client = client;
+ mutex_init(&data->lock);
+ data->input_limit = MAX127_INPUT_LIMIT;
+ for (i = 0; i < ARRAY_SIZE(data->ctrl_byte); i++)
+ data->ctrl_byte[i] = (MAX127_CTRL_START |
+ MAX127_SET_CHANNEL(i));
+
+ hwmon_dev = devm_hwmon_device_register_with_groups(dev,
+ client->name, data, max127_groups);
+
+ return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct i2c_device_id max127_id[] = {
+ { "max127", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, max127_id);
+
+static struct i2c_driver max127_driver = {
+ .class = I2C_CLASS_HWMON,
+ .driver = {
+ .name = "max127",
+ },
+ .probe = max127_probe,
+ .id_table = max127_id,
+};
+
+module_i2c_driver(max127_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Mike Choi <mikechoi@fb.com>");
+MODULE_AUTHOR("Tao Ren <rentao.bupt@gmail.com>");
+MODULE_DESCRIPTION("MAX127 Hardware Monitoring driver");
--
2.17.1