Re: [lm-sensors] [PATCH] hwmon: add driver for Microchip TC74
From: Guenter Roeck
Date: Sun Jun 21 2015 - 09:20:36 EST
On 06/21/2015 05:38 AM, Maciej S. Szmigiero wrote:
Add hwmon driver for the Microchip TC74.
The TC74 is a single-input 8-bit I2C temperature sensor,
with +-2 degrees centigrade accuracy.
Signed-off-by: Maciej Szmigiero <mail@xxxxxxxxxxxxxxxxxxxxx>
diff --git a/Documentation/hwmon/tc74 b/Documentation/hwmon/tc74
new file mode 100644
index 0000000..caecb1f
--- /dev/null
+++ b/Documentation/hwmon/tc74
@@ -0,0 +1,20 @@
+Kernel driver tc74
+====================
+
+Supported chips:
+ * Microchip TC74
+ Prefix: 'tc74'
+ Datasheet: Publicly available at Microchip website.
+
+Description
+-----------
+
+Driver supports the above part.
+
+The tc74 has an 8-bit sensor, with 1 degree centigrade resolution
+and +- 2 degrees centigrade accuracy.
+
+Notes
+-----
+
+Currently entering low power standby mode is not supported.
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 25d9e72..bbaaa2e 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1452,6 +1452,16 @@ config SENSORS_INA2XX
This driver can also be built as a module. If so, the module
will be called ina2xx.
+config SENSORS_TC74
+ tristate "Microchip TC74"
+ depends on I2C
+ help
+ If you say yes here you get support for Microchip TC74 single
+ input temperature sensor chips.
+
+ This driver can also be built as a module. If so, the module
+ will be called tc74.
+
config SENSORS_THMC50
tristate "Texas Instruments THMC50 / Analog Devices ADM1022"
depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index b4a40f1..ab90402 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -140,6 +140,7 @@ obj-$(CONFIG_SENSORS_SMSC47B397)+= smsc47b397.o
obj-$(CONFIG_SENSORS_SMSC47M1) += smsc47m1.o
obj-$(CONFIG_SENSORS_SMSC47M192)+= smsc47m192.o
obj-$(CONFIG_SENSORS_AMC6821) += amc6821.o
+obj-$(CONFIG_SENSORS_TC74) += tc74.o
obj-$(CONFIG_SENSORS_THMC50) += thmc50.o
obj-$(CONFIG_SENSORS_TMP102) += tmp102.o
obj-$(CONFIG_SENSORS_TMP103) += tmp103.o
diff --git a/drivers/hwmon/tc74.c b/drivers/hwmon/tc74.c
new file mode 100644
index 0000000..5000c58
--- /dev/null
+++ b/drivers/hwmon/tc74.c
@@ -0,0 +1,191 @@
+/*
+ * An hwmon driver for the Microchip TC74
+ *
+ * Copyright 2015 Maciej Szmigiero <mail@xxxxxxxxxxxxxxxxxxxxx>
+ *
+ * Based on ad7414.c:
+ * Copyright 2006 Stefan Roese, DENX Software Engineering
+ * Copyright 2008 Sean MacLennan, PIKA Technologies
+ * Copyright 2008 Frank Edelhaeuser, Spansion Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/jiffies.h>
+#include <linux/i2c.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/err.h>
+#include <linux/mutex.h>
+#include <linux/sysfs.h>
+#include <linux/slab.h>
+
Include files in alphabetic order, please.
+/* TC74 registers */
+#define TC74_REG_TEMP 0x00
+#define TC74_REG_CONFIG 0x01
+
+struct tc74_data {
+ struct i2c_client *client;
+ struct mutex lock; /* atomic read data updates */
+ char valid; /* !=0 if following fields are valid */
bool, please, and use true/false.
+ unsigned long next_update; /* In jiffies */
+ s8 temp_input; /* Temp value in dC */
+};
+
+static inline s8 tc74_temp_from_reg(s32 reg)
+{
+ u8 v8 = reg & 0xff;
+
+ return (s8)v8;
+}
+
+static inline s32 tc74_read(struct i2c_client *client, u8 reg)
+{
+ return i2c_smbus_read_byte_data(client, reg);
+}
+
+static inline s32 tc74_write(struct i2c_client *client, u8 reg, u8 value)
+{
+ return i2c_smbus_write_byte_data(client, reg, value);
+}
+
Those three functions are unnecessary; please drop.
+static int tc74_update_device(struct device *dev)
+{
+ struct tc74_data *data = dev_get_drvdata(dev);
+ struct i2c_client *client = data->client;
+ int ret;
+
+ ret = mutex_lock_interruptible(&data->lock);
+ if (ret)
+ return ret;
+
+ if (time_after(jiffies, data->next_update) || !data->valid) {
+ s32 value;
+
+ value = tc74_read(client, TC74_REG_CONFIG);
+ if (value < 0) {
+ dev_dbg(&client->dev, "TC74_REG_CONFIG read err %d\n",
+ (int)value);
+
+ ret = value;
+ goto ret_unlock;
+ }
+
+ if (!(value & 1 << 6)) {
Please use BIT().
+ /* not ready yet */
+
+ ret = -EAGAIN;
+ goto ret_unlock;
+ }
+
+ value = tc74_read(client, TC74_REG_TEMP);
+ if (value < 0) {
+ dev_dbg(&client->dev, "TC74_REG_TEMP read err %d\n",
+ (int)value);
+
+ ret = value;
+ goto ret_unlock;
+ }
+
+ data->temp_input = tc74_temp_from_reg(value);
C handles type conversion automatically, so just assign the value.
+ data->next_update = jiffies + HZ / 4;
+ data->valid = 1;
+ }
+
+ret_unlock:
+ mutex_unlock(&data->lock);
+
+ return ret;
+}
+
+static ssize_t show_temp_input(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct tc74_data *data = dev_get_drvdata(dev);
+ int ret;linux-kernel@xxxxxxxxxxxxxxx
+
???? does this compile ???
+ ret = tc74_update_device(dev);
+ if (ret)
+ return ret;
+
+ return sprintf(buf, "%d\n", (int)(data->temp_input) * 1000);
Unnecessary typecast.
+}
+static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp_input, NULL, 0);
+
+static struct attribute *tc74_attrs[] = {
+ &sensor_dev_attr_temp1_input.dev_attr.attr,
+ NULL
+};
+
+ATTRIBUTE_GROUPS(tc74);
+
+static int tc74_probe(struct i2c_client *client,
+ const struct i2c_device_id *dev_id)
+{
+ struct device *dev = &client->dev;
+ struct tc74_data *data;
+ struct device *hwmon_dev;
+ s32 conf;
+
+ if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+ return -EOPNOTSUPP;
+
+ data = devm_kzalloc(dev, sizeof(struct tc74_data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ data->client = client;
+ mutex_init(&data->lock);
+
+ /* Make sure the chip is powered up. */
+ conf = tc74_read(client, TC74_REG_CONFIG);
+ if (conf < 0) {
+ dev_err(dev, "unable to read config register\n");
+
+ return conf;
+ } else if (conf & 0x3f) {
+ dev_err(dev, "invalid config register value\n");
+
+ return -ENODEV;
+ } else if (conf & 1 << 7) {
Please use BIT().
The else cases are all not needed.
+ s32 ret;
+
+ conf &= ~(1 << 7);
Please use BIT.
+
+ ret = tc74_write(client, TC74_REG_CONFIG, conf);
+ if (ret)
+ dev_warn(dev, "unable to disable STANDBY\n");
+ }
+
+ dev_info(&client->dev, "chip found\n");
+
Unnecessary noise; please drop.
Thanks,
Guenter
+ hwmon_dev = devm_hwmon_device_register_with_groups(dev,
+ client->name,
+ data, tc74_groups);
+ return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct i2c_device_id tc74_id[] = {
+ { "tc74", 0 },
+ {}
+};
+MODULE_DEVICE_TABLE(i2c, tc74_id);
+
+static struct i2c_driver tc74_driver = {
+ .driver = {
+ .name = "tc74",
+ },
+ .probe = tc74_probe,
+ .id_table = tc74_id,
+};
+
+module_i2c_driver(tc74_driver);
+
+MODULE_AUTHOR("Maciej Szmigiero <mail@xxxxxxxxxxxxxxxxxxxxx>");
+
+MODULE_DESCRIPTION("TC74 driver");
+MODULE_LICENSE("GPL");
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