linux-kernel - Re: [PATCH v5 6/7] hwmon: pmbus: adm1266: debugfs for blackbox info

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Date:   Wed, 24 Jun 2020 14:53:18 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     alexandru.tachici@...log.com
Cc:     linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, robh+dt@...nel.org
Subject: Re: [PATCH v5 6/7] hwmon: pmbus: adm1266: debugfs for blackbox info

On Wed, Jun 24, 2020 at 06:17:35PM +0300, alexandru.tachici@...log.com wrote:
> From: Alexandru Tachici <alexandru.tachici@...log.com>
> 
> Add a debugfs file to print information in the
> BLACKBOX_INFORMATION register. Contains information
> about the number of stored records, logic index and id
> of the latest record.

How is this different to the nvram method implemented in toe previous patch ?
Why do we need both ?

> 
> Signed-off-by: Alexandru Tachici <alexandru.tachici@...log.com>
> ---
>  drivers/hwmon/pmbus/adm1266.c | 56 ++++++++++++++++++++++++++++++++++-
>  1 file changed, 55 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/hwmon/pmbus/adm1266.c b/drivers/hwmon/pmbus/adm1266.c
> index b9e92ab1e39a..ea2dc481094b 100644
> --- a/drivers/hwmon/pmbus/adm1266.c
> +++ b/drivers/hwmon/pmbus/adm1266.c
> @@ -60,6 +60,7 @@ struct adm1266_data {
>  	const char *gpio_names[ADM1266_GPIO_NR + ADM1266_PDIO_NR];
>  	struct i2c_client *client;
>  	struct mutex ioctl_mutex; /* lock ioctl access */
> +	struct dentry *debugfs_dir;
>  	struct nvmem_config nvmem_config;
>  	struct nvmem_device *nvmem;
>  	u8 *dev_mem;
> @@ -406,6 +407,28 @@ static const struct proc_ops adm1266_proc_ops = {
>  	.proc_ioctl	= adm1266_ioctl,
>  };
>  
> +static int adm1266_blackbox_information_read(struct seq_file *s, void *pdata)
> +{
> +	struct device *dev = s->private;
> +	struct i2c_client *client = to_i2c_client(dev);
> +	u8 read_buf[5];
> +	unsigned int latest_id;
> +	int ret;
> +
> +	ret = i2c_smbus_read_block_data(client, ADM1266_BLACKBOX_INFO,
> +					read_buf);
> +	if (ret < 0)
> +		return ret;
> +
> +	seq_puts(s, "BLACKBOX_INFORMATION:\n");
> +	latest_id = read_buf[0] + (read_buf[1] << 8);
> +	seq_printf(s, "Black box ID: %u\n", latest_id);
> +	seq_printf(s, "Logic index: %u\n", read_buf[2]);
> +	seq_printf(s, "Record count: %u\n", read_buf[3]);
> +
> +	return 0;
> +}
> +
>  static int adm1266_init_procfs(struct adm1266_data *data)
>  {
>  	struct proc_dir_entry *proc_dir;
> @@ -423,6 +446,29 @@ static int adm1266_init_procfs(struct adm1266_data *data)
>  	return 0;
>  }
>  
> +static int adm1266_init_debugfs(struct adm1266_data *data)
> +{
> +	struct dentry *entry;
> +	struct dentry *root;
> +
> +	root = pmbus_get_debugfs_dir(data->client);
> +	if (!root)
> +		return -ENOENT;
> +
> +	data->debugfs_dir = debugfs_create_dir(data->client->name, root);
> +	if (!data->debugfs_dir)
> +		return -ENOENT;
> +
> +	entry = debugfs_create_devm_seqfile(&data->client->dev,
> +					    "blackbox_information",
> +					    data->debugfs_dir,
> +					    adm1266_blackbox_information_read);
> +	if (!entry)
> +		return -ENOENT;
> +
> +	return 0;
> +}
> +
>  static int adm1266_nvmem_read_blackbox(struct adm1266_data *data, u8 *buf)
>  {
>  	u8 read_buf[5];
> @@ -571,7 +617,15 @@ static int adm1266_probe(struct i2c_client *client,
>  	for (i = 0; i < info->pages; i++)
>  		info->func[i] = funcs;
>  
> -	return pmbus_do_probe(client, id, info);
> +	ret = pmbus_do_probe(client, id, info);
> +	if (ret)
> +		return ret;
> +
> +	ret = adm1266_init_debugfs(data);
> +	if (ret)
> +		dev_warn(&client->dev, "Failed to register debugfs: %d\n", ret);

debugfs functions are supposed to fail silently.

> +
> +	return 0;
>  }
>  
>  static const struct of_device_id adm1266_of_match[] = {