Re: [PATCH] hwmon: (ibmpowernv) Use platform 'id_table' to probe the device

[Guenter Roeck]

On 11/03/2014 11:30 PM, Neelesh Gupta wrote:
> The current driver probe() function assumes the sensor device to be
> alwary present and gets executed every time if the driver is loaded,
> but the appropriate hardware could not be present.
>
> So, move the platform device creation as part of platform init code
> and use the 'id_table' to check if the device present or not.
>
> Signed-off-by: Neelesh Gupta <neelegup@xxxxxxxxxxxxxxxxxx>
> ---
>   arch/powerpc/platforms/powernv/opal-sensor.c |   20 ++++++++
>   drivers/hwmon/ibmpowernv.c                   |   67 +++++++-------------------
>   2 files changed, 39 insertions(+), 48 deletions(-)
>
> diff --git a/arch/powerpc/platforms/powernv/opal-sensor.c b/arch/powerpc/platforms/powernv/opal-sensor.c
> index 10271ad..215c418 100644
> --- a/arch/powerpc/platforms/powernv/opal-sensor.c
> +++ b/arch/powerpc/platforms/powernv/opal-sensor.c
> @@ -20,7 +20,9 @@
>
>   #include <linux/delay.h>
>   #include <linux/mutex.h>
> +#include <linux/of_platform.h>
>   #include <asm/opal.h>
> +#include <asm/machdep.h>
>
>   static DEFINE_MUTEX(opal_sensor_mutex);
>
> @@ -64,3 +66,21 @@ out:
>   	return ret;
>   }
>   EXPORT_SYMBOL_GPL(opal_get_sensor_data);
> +
> +static __init int opal_sensor_init(void)
> +{
> +	struct platform_device *pdev;
> +	struct device_node *sensor;
> +
> +	sensor = of_find_node_by_path("/ibm,opal/sensors");
> +	if (sensor) {
> +		pdev = of_platform_device_create(sensor, "opal-sensor", NULL);
> +		of_node_put(sensor);
> +	} else {
> +		pr_info("Opal node 'sensors' not found\n");

Hi Neelesh,

this is either an error and should be reported with pr_err, or it is
a valid condition and should be reported with pr_debug or not at all.

Which one is it ?

Also, can you put this code into a 'normal' error handler instead of using if/else ?

	if (!sensor) {
		pr_err("Opal node 'sensors' not found\n");
		return -ENODEV;
	}
	pdev = of_platform_device_create(sensor, "opal-sensor", NULL);
	...

This would make the code flow easier to understand.

Thanks,
Guenter

> +		return -ENODEV;
> +	}
> +
> +	return PTR_ERR_OR_ZERO(pdev);
> +}
> +machine_subsys_initcall(powernv, opal_sensor_init);
> diff --git a/drivers/hwmon/ibmpowernv.c b/drivers/hwmon/ibmpowernv.c
> index 6a30eee..c7577b8 100644
> --- a/drivers/hwmon/ibmpowernv.c
> +++ b/drivers/hwmon/ibmpowernv.c
> @@ -74,9 +74,6 @@ struct platform_data {
>   	u32 sensors_count; /* Total count of sensors from each group */
>   };
>
> -/* Platform device representing all the ibmpowernv sensors */
> -static struct platform_device *pdevice;
> -
>   static ssize_t show_sensor(struct device *dev, struct device_attribute *devattr,
>   			   char *buf)
>   {
> @@ -99,7 +96,7 @@ static ssize_t show_sensor(struct device *dev, struct device_attribute *devattr,
>   	return sprintf(buf, "%u\n", x);
>   }
>
> -static int __init get_sensor_index_attr(const char *name, u32 *index,
> +static int get_sensor_index_attr(const char *name, u32 *index,
>   					char *attr)
>   {
>   	char *hash_pos = strchr(name, '#');
> @@ -136,7 +133,7 @@ static int __init get_sensor_index_attr(const char *name, u32 *index,
>    * which need to be mapped as fan2_input, temp1_max respectively before
>    * populating them inside hwmon device class.
>    */
> -static int __init create_hwmon_attr_name(struct device *dev, enum sensors type,
> +static int create_hwmon_attr_name(struct device *dev, enum sensors type,
>   					 const char *node_name,
>   					 char *hwmon_attr_name)
>   {
> @@ -172,7 +169,7 @@ static int __init create_hwmon_attr_name(struct device *dev, enum sensors type,
>   	return 0;
>   }
>
> -static int __init populate_attr_groups(struct platform_device *pdev)
> +static int populate_attr_groups(struct platform_device *pdev)
>   {
>   	struct platform_data *pdata = platform_get_drvdata(pdev);
>   	const struct attribute_group **pgroups = pdata->attr_groups;
> @@ -180,11 +177,6 @@ static int __init populate_attr_groups(struct platform_device *pdev)
>   	enum sensors type;
>
>   	opal = of_find_node_by_path("/ibm,opal/sensors");
> -	if (!opal) {
> -		dev_dbg(&pdev->dev, "Opal node 'sensors' not found\n");
> -		return -ENODEV;
> -	}
> -
>   	for_each_child_of_node(opal, np) {
>   		if (np->name == NULL)
>   			continue;
> @@ -221,7 +213,7 @@ static int __init populate_attr_groups(struct platform_device *pdev)
>    * to the name required by the higher 'hwmon' driver like fan1_input, temp1_max
>    * etc..
>    */
> -static int __init create_device_attrs(struct platform_device *pdev)
> +static int create_device_attrs(struct platform_device *pdev)
>   {
>   	struct platform_data *pdata = platform_get_drvdata(pdev);
>   	const struct attribute_group **pgroups = pdata->attr_groups;
> @@ -280,7 +272,7 @@ exit_put_node:
>   	return err;
>   }
>
> -static int __init ibmpowernv_probe(struct platform_device *pdev)
> +static int ibmpowernv_probe(struct platform_device *pdev)
>   {
>   	struct platform_data *pdata;
>   	struct device *hwmon_dev;
> @@ -309,52 +301,31 @@ static int __init ibmpowernv_probe(struct platform_device *pdev)
>   	return PTR_ERR_OR_ZERO(hwmon_dev);
>   }
>
> +static const struct platform_device_id opal_sensor_driver_ids[] = {
> +	{
> +		.name = "opal-sensor",
> +	},
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(platform, opal_sensor_driver_ids);
> +
>   static struct platform_driver ibmpowernv_driver = {
> -	.driver = {
> -		.owner = THIS_MODULE,
> -		.name = DRVNAME,
> +	.probe		= ibmpowernv_probe,
> +	.id_table	= opal_sensor_driver_ids,
> +	.driver		= {
> +		.owner	= THIS_MODULE,
> +		.name	= DRVNAME,
>   	},
>   };
>
>   static int __init ibmpowernv_init(void)
>   {
> -	int err;
> -
> -	pdevice = platform_device_alloc(DRVNAME, 0);
> -	if (!pdevice) {
> -		pr_err("Device allocation failed\n");
> -		err = -ENOMEM;
> -		goto exit;
> -	}
> -
> -	err = platform_device_add(pdevice);
> -	if (err) {
> -		pr_err("Device addition failed (%d)\n", err);
> -		goto exit_device_put;
> -	}
> -
> -	err = platform_driver_probe(&ibmpowernv_driver, ibmpowernv_probe);
> -	if (err) {
> -		if (err != -ENODEV)
> -			pr_err("Platform driver probe failed (%d)\n", err);
> -
> -		goto exit_device_del;
> -	}
> -
> -	return 0;
> -
> -exit_device_del:
> -	platform_device_del(pdevice);
> -exit_device_put:
> -	platform_device_put(pdevice);
> -exit:
> -	return err;
> +	return platform_driver_register(&ibmpowernv_driver);
>   }
>
>   static void __exit ibmpowernv_exit(void)
>   {
>   	platform_driver_unregister(&ibmpowernv_driver);
> -	platform_device_unregister(pdevice);
>   }
>
>   MODULE_AUTHOR("Neelesh Gupta <neelegup@xxxxxxxxxxxxxxxxxx>");

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