Re: [lm-sensors] [PATCH] hwmon: add driver for Microchip TC74

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Hello Guenter,

Thanks for your review.

Best regards,
Maciej Szmigiero

W dniu 21.06.2015 15:19, Guenter Roeck pisze:
> 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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