Re: [PATCH 2/2] hwmon: (max6650) Convert to be a platform driver

From: Guenter Roeck
Date: Fri Feb 14 2014 - 12:45:20 EST

On Fri, Feb 14, 2014 at 09:15:42AM +0000, Laszlo Papp wrote:
> The MFD driver has now been added, so this driver is now being adopted to be a
> subdevice driver on top of it. This means, the i2c driver usage is being
> converted to platform driver usage all around.
>
> Signed-off-by: Laszlo Papp <lpapp@xxxxxxx>
> ---
> drivers/hwmon/Kconfig | 2 +-
> drivers/hwmon/max6650.c | 125 ++++++++++++++++++++++++------------------------
> 2 files changed, 63 insertions(+), 64 deletions(-)
>
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 7ed3aa6..fcfe484 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -962,7 +962,7 @@ config SENSORS_MAX6642
>
> config SENSORS_MAX6650
> tristate "Maxim MAX6650 sensor chip"
> - depends on I2C
> + depends on MFD_MAX665X
> help
> If you say yes here you get support for the MAX6650 / MAX6651
> sensor chips.
> diff --git a/drivers/hwmon/max6650.c b/drivers/hwmon/max6650.c
> index 162a520..4d79413 100644
> --- a/drivers/hwmon/max6650.c
> +++ b/drivers/hwmon/max6650.c
> @@ -39,6 +39,9 @@
> #include <linux/hwmon.h>
> #include <linux/hwmon-sysfs.h>
> #include <linux/err.h>
> +#include <linux/platform_device.h>
> +
> +#include <linux/mfd/max665x-private.h>

'private' is a somewhat unusual file name in a global include file.
Why not just max665x.h ?

>
> /*
> * Insmod parameters
> @@ -112,18 +115,19 @@ module_param(clock, int, S_IRUGO);
> struct max6650_data {
> struct i2c_client *client;

client is no longer needed, and all other references to i2c
(such as include files) should be removed as well.

> const struct attribute_group *groups[3];
> + struct max665x_dev *iodev;

The only use of this variable is to dereference map. 'struct regmap *map'
might thus make more sense here.

Also, iodev is not initialized. The first access to iodev->map will result
in a null pointer access.

> struct mutex update_lock;
> int nr_fans;
> char valid; /* zero until following fields are valid */
> unsigned long last_updated; /* in jiffies */
>
> /* register values */
> - u8 speed;
> - u8 config;
> - u8 tach[4];
> - u8 count;
> - u8 dac;
> - u8 alarm;
> + int speed;
> + int config;
> + int tach[4];
> + int count;
> + int dac;
> + int alarm;
> };
>
> static const u8 tach_reg[] = {
> @@ -136,31 +140,29 @@ static const u8 tach_reg[] = {
> static struct max6650_data *max6650_update_device(struct device *dev)
> {
> struct max6650_data *data = dev_get_drvdata(dev);
> - struct i2c_client *client = data->client;
> + struct regmap *map = data->iodev->map;
> int i;
> + int alarm;
>
> mutex_lock(&data->update_lock);
>
> if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
> - data->speed = i2c_smbus_read_byte_data(client,
> - MAX6650_REG_SPEED);
> - data->config = i2c_smbus_read_byte_data(client,
> - MAX6650_REG_CONFIG);
> + regmap_read(map, MAX6650_REG_SPEED, &data->speed);
> + regmap_read(map, MAX6650_REG_CONFIG, &data->config);
> for (i = 0; i < data->nr_fans; i++) {
> - data->tach[i] = i2c_smbus_read_byte_data(client,
> - tach_reg[i]);
> + data->tach[i] = regmap_read(map, tach_reg[i],
> + &data->tach[i]);
> }
> - data->count = i2c_smbus_read_byte_data(client,
> - MAX6650_REG_COUNT);
> - data->dac = i2c_smbus_read_byte_data(client, MAX6650_REG_DAC);
> + regmap_read(map, MAX6650_REG_COUNT, &data->count);
> + regmap_read(map, MAX6650_REG_DAC, &data->dac);
>
> /*
> * 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.
> */
> - data->alarm |= i2c_smbus_read_byte_data(client,
> - MAX6650_REG_ALARM);
> + regmap_read(map, MAX6650_REG_ALARM, &alarm);
> + data->alarm |= alarm;
>
> data->last_updated = jiffies;
> data->valid = 1;
> @@ -256,7 +258,6 @@ static ssize_t set_target(struct device *dev, struct device_attribute *devattr,
> const char *buf, size_t count)
> {
> struct max6650_data *data = dev_get_drvdata(dev);
> - struct i2c_client *client = data->client;
> int kscale, ktach;
> unsigned long rpm;
> int err;
> @@ -284,7 +285,7 @@ static ssize_t set_target(struct device *dev, struct device_attribute *devattr,
> ktach = 255;
> data->speed = ktach;
>
> - i2c_smbus_write_byte_data(client, MAX6650_REG_SPEED, data->speed);
> + regmap_write(data->iodev->map, MAX6650_REG_SPEED, data->speed);
>
> mutex_unlock(&data->update_lock);
>
> @@ -325,7 +326,6 @@ static ssize_t set_pwm(struct device *dev, struct device_attribute *devattr,
> const char *buf, size_t count)
> {
> struct max6650_data *data = dev_get_drvdata(dev);
> - struct i2c_client *client = data->client;
> unsigned long pwm;
> int err;
>
> @@ -342,7 +342,7 @@ static ssize_t set_pwm(struct device *dev, struct device_attribute *devattr,
> else
> data->dac = 76 - (76 * pwm)/255;
>
> - i2c_smbus_write_byte_data(client, MAX6650_REG_DAC, data->dac);
> + regmap_write(data->iodev->map, MAX6650_REG_DAC, data->dac);
>
> mutex_unlock(&data->update_lock);
>
> @@ -371,7 +371,7 @@ static ssize_t set_enable(struct device *dev, struct device_attribute *devattr,
> const char *buf, size_t count)
> {
> struct max6650_data *data = dev_get_drvdata(dev);
> - struct i2c_client *client = data->client;
> + struct regmap *map = data->iodev->map;
> int max6650_modes[3] = {0, 3, 2};
> unsigned long mode;
> int err;
> @@ -385,11 +385,11 @@ static ssize_t set_enable(struct device *dev, struct device_attribute *devattr,
>
> mutex_lock(&data->update_lock);
>
> - data->config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);
> + regmap_read(map, MAX6650_REG_CONFIG, &data->config);
> data->config = (data->config & ~MAX6650_CFG_MODE_MASK)
> | (max6650_modes[mode] << 4);
>
> - i2c_smbus_write_byte_data(client, MAX6650_REG_CONFIG, data->config);
> + regmap_write(map, MAX6650_REG_CONFIG, data->config);
>
> mutex_unlock(&data->update_lock);
>
> @@ -421,7 +421,6 @@ static ssize_t set_div(struct device *dev, struct device_attribute *devattr,
> const char *buf, size_t count)
> {
> struct max6650_data *data = dev_get_drvdata(dev);
> - struct i2c_client *client = data->client;
> unsigned long div;
> int err;
>
> @@ -448,7 +447,7 @@ static ssize_t set_div(struct device *dev, struct device_attribute *devattr,
> return -EINVAL;
> }
>
> - i2c_smbus_write_byte_data(client, MAX6650_REG_COUNT, data->count);
> + regmap_write(data->iodev->map, MAX6650_REG_COUNT, data->count);
> mutex_unlock(&data->update_lock);
>
> return count;
> @@ -465,16 +464,15 @@ static ssize_t get_alarm(struct device *dev, struct device_attribute *devattr,
> char *buf)
> {
> struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
> - struct max6650_data *data = max6650_update_device(dev);
> - struct i2c_client *client = data->client;
> + struct max6650_data *data = dev_get_drvdata(dev);
> int alarm = 0;
>
> if (data->alarm & attr->index) {
> mutex_lock(&data->update_lock);
> - alarm = 1;
> data->alarm &= ~attr->index;
> - data->alarm |= i2c_smbus_read_byte_data(client,
> - MAX6650_REG_ALARM);
> + regmap_read(data->iodev->map, MAX6650_REG_ALARM, &alarm);
> + data->alarm |= alarm;
> + alarm = 1;
> mutex_unlock(&data->update_lock);
> }
>
> @@ -505,10 +503,11 @@ static umode_t max6650_attrs_visible(struct kobject *kobj, struct attribute *a,
> {
> struct device *dev = container_of(kobj, struct device, kobj);
> struct max6650_data *data = dev_get_drvdata(dev);
> - struct i2c_client *client = data->client;
> - u8 alarm_en = i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM_EN);
> + int alarm_en;
> struct device_attribute *devattr;
>
> + regmap_read(data->iodev->map, MAX6650_REG_ALARM_EN, &alarm_en);
> +

There is now a difference in handline alarm_en and in general
return values from i2c_smbus_read_byte_data vs. regmap_read.
alarm_en is no longer initialized if regmap_read() returns an error.
It will therefore be necessary to check the return values or pre-initialize
the variable. The same applies to all other places where the reeturn value of
regmap_read is not checked.

> /*
> * Hide the alarms that have not been enabled by the firmware
> */
> @@ -560,17 +559,17 @@ static const struct attribute_group max6651_group = {
> * Real code
> */
>
> -static int max6650_init_client(struct max6650_data *data,
> - struct i2c_client *client)
> +static int max6650_init_client(struct platform_device *pdev)
> {
> - struct device *dev = &client->dev;

I had a reason for introducing this variable here and in the probe function.
Please don't remove it.

> + struct max6650_data *data = platform_get_drvdata(pdev);
> + struct regmap *map = data->iodev->map;
> int config;
> int err = -EIO;
>
> - config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);
> + regmap_read(map, MAX6650_REG_CONFIG, &config);
>
> if (config < 0) {
> - dev_err(dev, "Error reading config, aborting.\n");
> + dev_err(&pdev->dev, "Error reading config, aborting.\n");
> return err;
> }
>
> @@ -584,11 +583,11 @@ static int max6650_init_client(struct max6650_data *data,
> config |= MAX6650_CFG_V12;
> break;
> default:
> - dev_err(dev, "illegal value for fan_voltage (%d)\n",
> + dev_err(&pdev->dev, "illegal value for fan_voltage (%d)\n",
> fan_voltage);
> }
>
> - dev_info(dev, "Fan voltage is set to %dV.\n",
> + dev_info(&pdev->dev, "Fan voltage is set to %dV.\n",
> (config & MAX6650_CFG_V12) ? 12 : 5);
>
> switch (prescaler) {
> @@ -614,10 +613,11 @@ static int max6650_init_client(struct max6650_data *data,
> | MAX6650_CFG_PRESCALER_16;
> break;
> default:
> - dev_err(dev, "illegal value for prescaler (%d)\n", prescaler);
> + dev_err(&pdev->dev, "illegal value for prescaler (%d)\n",
> + prescaler);
> }
>
> - dev_info(dev, "Prescaler is set to %d.\n",
> + dev_info(&pdev->dev, "Prescaler is set to %d.\n",
> 1 << (config & MAX6650_CFG_PRESCALER_MASK));
>
> /*
> @@ -627,46 +627,45 @@ static int max6650_init_client(struct max6650_data *data,
> */
>
> if ((config & MAX6650_CFG_MODE_MASK) == MAX6650_CFG_MODE_OFF) {
> - dev_dbg(dev, "Change mode to open loop, full off.\n");
> + dev_dbg(&pdev->dev, "Change mode to open loop, full off.\n");
> config = (config & ~MAX6650_CFG_MODE_MASK)
> | MAX6650_CFG_MODE_OPEN_LOOP;
> - if (i2c_smbus_write_byte_data(client, MAX6650_REG_DAC, 255)) {
> - dev_err(dev, "DAC write error, aborting.\n");
> + if (regmap_write(data->iodev->map, MAX6650_REG_DAC, 255) < 0) {
> + dev_err(&pdev->dev, "DAC write error, aborting.\n");
> return err;
> }
> }
>
> - if (i2c_smbus_write_byte_data(client, MAX6650_REG_CONFIG, config)) {
> - dev_err(dev, "Config write error, aborting.\n");
> + if (regmap_write(map, MAX6650_REG_CONFIG, config) < 0) {
> + dev_err(&pdev->dev, "Config write error, aborting.\n");
> return err;
> }
>
> data->config = config;
> - data->count = i2c_smbus_read_byte_data(client, MAX6650_REG_COUNT);
> + regmap_read(map, MAX6650_REG_COUNT, &data->count);
>
> return 0;
> }
>
> -static int max6650_probe(struct i2c_client *client,
> - const struct i2c_device_id *id)
> +static int max6650_probe(struct platform_device *pdev)
> {
> - struct device *dev = &client->dev;
> - struct max6650_data *data;
> + struct max6650_data *data = platform_get_drvdata(pdev);

driver data points to struct max665x_dev *.

This should probably be something like
struct max665x_dev *iodev = platform_get_drvdata(pdev);
as a separate variable. It also needs to be validated to ensure
that it is not NULL.

> + const struct platform_device_id *id = platform_get_device_id(pdev);
> struct device *hwmon_dev;
> int err;
>
> - data = devm_kzalloc(dev, sizeof(struct max6650_data), GFP_KERNEL);
> + data = devm_kzalloc(&pdev->dev, sizeof(struct max6650_data),
> + GFP_KERNEL);
> if (!data)
> return -ENOMEM;
>
> - data->client = client;

data->iodev = iodev;
or better
data->map = iodev->map;

is missing.

> mutex_init(&data->update_lock);
> data->nr_fans = id->driver_data;
>
> /*
> * Initialize the max6650 chip
> */
> - err = max6650_init_client(data, client);
> + err = max6650_init_client(pdev);
> if (err)
> return err;
>
> @@ -675,20 +674,20 @@ static int max6650_probe(struct i2c_client *client,
> if (data->nr_fans == 4)
> data->groups[1] = &max6651_group;
>
> - hwmon_dev = devm_hwmon_device_register_with_groups(dev,
> - client->name, data,
> - data->groups);
> + hwmon_dev = devm_hwmon_device_register_with_groups(&pdev->dev,
> + data->client->name,

This will crash (client is NULL).

You'll have to come up with a scheme to pass the device type from the mfd driver
to this one, and use "max6650" and "max6651" as names here.

> + data, data->groups);
> return PTR_ERR_OR_ZERO(hwmon_dev);
> }
>
> -static const struct i2c_device_id max6650_id[] = {
> +static const struct platform_device_id max6650_id[] = {
> { "max6650", 1 },
> { "max6651", 4 },
> { }
> };
> -MODULE_DEVICE_TABLE(i2c, max6650_id);
> +MODULE_DEVICE_TABLE(platform, max6650_id);
>
> -static struct i2c_driver max6650_driver = {
> +static struct platform_driver max6650_driver = {
> .driver = {
> .name = "max6650",
> },
> @@ -696,7 +695,7 @@ static struct i2c_driver max6650_driver = {
> .id_table = max6650_id,
> };
>
> -module_i2c_driver(max6650_driver);
> +module_platform_driver(max6650_driver);
>
> MODULE_AUTHOR("Hans J. Koch");
> MODULE_DESCRIPTION("MAX6650 sensor driver");
> --
> 1.8.5.4
>
>
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