linux-kernel - Re: [PATCH v4] hwmon: (max6650.c) Add devicetree support

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Message-ID: <47fa9220-4393-7c76-7a81-4127635712e3@roeck-us.net>
Date:   Thu, 18 Aug 2016 19:43:19 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Mike Looijmans <mike.looijmans@...ic.nl>, hjk@...sjkoch.de
Cc:     linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] hwmon: (max6650.c) Add devicetree support

On 08/16/2016 12:20 AM, Mike Looijmans wrote:
> Parse devicetree parameters for voltage and prescaler setting. This allows
> using multiple max6550 devices with varying settings, and also makes it
> possible to instantiate and configure the device using devicetree.
>
> Signed-off-by: Mike Looijmans <mike.looijmans@...ic.nl>
> ---
> v4: Vendor prefix "maxim," for devicetree properties and compatible string
>     Split documentation into separate patch
> v3: Resubmit because wrong mailing lists used
>     Fix style errors as reported by checkpatch.pl
>     Fix bug in DT parsing of fan-prescale
> v2: Add devicetree binding documentation
>     Code changes as suggested by Guenter
>     Reduce log info, output only a single line
>  drivers/hwmon/max6650.c | 47 ++++++++++++++++++++++++++++++++++++-----------
>  1 file changed, 36 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/hwmon/max6650.c b/drivers/hwmon/max6650.c
> index 162a520..6beb62c 100644
> --- a/drivers/hwmon/max6650.c
> +++ b/drivers/hwmon/max6650.c
> @@ -39,6 +39,7 @@
>  #include <linux/hwmon.h>
>  #include <linux/hwmon-sysfs.h>
>  #include <linux/err.h>
> +#include <linux/of_device.h>
>
>  /*
>   * Insmod parameters
> @@ -48,7 +49,7 @@
>  static int fan_voltage;
>  /* prescaler: Possible values are 1, 2, 4, 8, 16 or 0 for don't change */
>  static int prescaler;
> -/* clock: The clock frequency of the chip the driver should assume */
> +/* clock: The clock frequency of the chip (max6651 can be clocked externally) */
>  static int clock = 254000;
>
>  module_param(fan_voltage, int, S_IRUGO);
> @@ -133,6 +134,19 @@ static const u8 tach_reg[] = {
>  	MAX6650_REG_TACH3,
>  };
>
> +static const struct of_device_id max6650_dt_match[] = {
> +	{
> +		.compatible = "maxim,max6650",
> +		.data = (void *)1
> +	},
> +	{
> +		.compatible = "maxim,max6651",
> +		.data = (void *)4
> +	},
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, max6650_dt_match);
> +
>  static struct max6650_data *max6650_update_device(struct device *dev)
>  {
>  	struct max6650_data *data = dev_get_drvdata(dev);
> @@ -566,6 +580,17 @@ static int max6650_init_client(struct max6650_data *data,
>  	struct device *dev = &client->dev;
>  	int config;
>  	int err = -EIO;
> +	u32 voltage;
> +	u32 prescale;
> +
> +	if (of_property_read_u32(dev->of_node, "maxim,fan-microvolt",
> +				 &voltage))
> +		voltage = fan_voltage;
> +	else
> +		voltage = voltage > 5500000 ? 12 : 5;

I think this should only accept 5V or 12V.

Guenter

> +	if (of_property_read_u32(dev->of_node, "maxim,fan-prescale",
> +				 &prescale))
> +		prescale = prescaler;
>
>  	config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);
>
> @@ -574,7 +599,7 @@ static int max6650_init_client(struct max6650_data *data,
>  		return err;
>  	}
>
> -	switch (fan_voltage) {
> +	switch (voltage) {
>  	case 0:
>  		break;
>  	case 5:
> @@ -584,14 +609,10 @@ 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",
> -			fan_voltage);
> +		dev_err(dev, "illegal value for fan_voltage (%d)\n", voltage);
>  	}
>
> -	dev_info(dev, "Fan voltage is set to %dV.\n",
> -		 (config & MAX6650_CFG_V12) ? 12 : 5);
> -
> -	switch (prescaler) {
> +	switch (prescale) {
>  	case 0:
>  		break;
>  	case 1:
> @@ -614,10 +635,11 @@ 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(dev, "illegal value for prescaler (%d)\n", prescale);
>  	}
>
> -	dev_info(dev, "Prescaler is set to %d.\n",
> +	dev_info(dev, "Fan voltage: %dV, prescaler: %d.\n",
> +		 (config & MAX6650_CFG_V12) ? 12 : 5,
>  		 1 << (config & MAX6650_CFG_PRESCALER_MASK));
>
>  	/*
> @@ -651,6 +673,8 @@ static int max6650_probe(struct i2c_client *client,
>  			 const struct i2c_device_id *id)
>  {
>  	struct device *dev = &client->dev;
> +	const struct of_device_id *of_id =
> +		of_match_device(of_match_ptr(max6650_dt_match), dev);
>  	struct max6650_data *data;
>  	struct device *hwmon_dev;
>  	int err;
> @@ -661,7 +685,7 @@ static int max6650_probe(struct i2c_client *client,
>
>  	data->client = client;
>  	mutex_init(&data->update_lock);
> -	data->nr_fans = id->driver_data;
> +	data->nr_fans = of_id ? (int)(uintptr_t)of_id->data : id->driver_data;
>
>  	/*
>  	 * Initialize the max6650 chip
> @@ -691,6 +715,7 @@ MODULE_DEVICE_TABLE(i2c, max6650_id);
>  static struct i2c_driver max6650_driver = {
>  	.driver = {
>  		.name	= "max6650",
> +		.of_match_table = of_match_ptr(max6650_dt_match),
>  	},
>  	.probe		= max6650_probe,
>  	.id_table	= max6650_id,
>