Re: [PATCH] hwmon: (pmbus) Add debugfs output voltage related commands

[Guenter Roeck <linux@roeck-us.net>]

On Tue, Sep 06, 2022 at 11:27:43AM +0200, Mårten Lindahl wrote:
> Export vout_command, vout_margin_high, and vout_margin_low through
> debugfs. This is useful in order to manually configure the output
> voltage on a channel.
> 

NACK, voltages must be set through regulators which is already supported.
We are not going to start bypassing regulators. Also, I don't think it
is a good idea to allow manipulating margin voltages. Those are critical
and should be set by manufacturing.

Guenter

> Signed-off-by: Mårten Lindahl <marten.lindahl@axis.com>
> ---
>  drivers/hwmon/pmbus/pmbus_core.c | 80 +++++++++++++++++++++++++++++++-
>  1 file changed, 78 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
> index 81d3f91dd204..25da2ff2d09f 100644
> --- a/drivers/hwmon/pmbus/pmbus_core.c
> +++ b/drivers/hwmon/pmbus/pmbus_core.c
> @@ -3050,6 +3050,41 @@ static int pmbus_debugfs_get(void *data, u64 *val)
>  DEFINE_DEBUGFS_ATTRIBUTE(pmbus_debugfs_ops, pmbus_debugfs_get, NULL,
>  			 "0x%02llx\n");
>  
> +static int pmbus_debugfs_get_word(void *data, u64 *val)
> +{
> +	struct pmbus_debugfs_entry *entry = data;
> +	struct pmbus_sensor s = {
> +		.page = entry->page,
> +		.class = PSC_VOLTAGE_OUT,
> +		.convert = true,
> +		.data = -1,
> +	};
> +
> +	s.data = _pmbus_read_word_data(entry->client, entry->page, 0xff, entry->reg);
> +	if (s.data < 0)
> +		return s.data;
> +	*val = pmbus_reg2data(i2c_get_clientdata(entry->client), &s);
> +
> +	return 0;
> +}
> +
> +static int pmbus_debugfs_set_word(void *data, u64 val)
> +{
> +	struct pmbus_debugfs_entry *entry = data;
> +	struct pmbus_sensor s = {
> +		.page = entry->page,
> +		.class = PSC_VOLTAGE_OUT,
> +		.convert = true,
> +		.data = -1,
> +	};
> +	val = pmbus_data2reg(i2c_get_clientdata(entry->client), &s, val);
> +
> +	return _pmbus_write_word_data(entry->client, entry->page, entry->reg,
> +				      (u16)val);
> +}
> +DEFINE_DEBUGFS_ATTRIBUTE(pmbus_debugfs_ops_rw_word, pmbus_debugfs_get_word,
> +			 pmbus_debugfs_set_word, "%llu\n");
> +
>  static int pmbus_debugfs_get_status(void *data, u64 *val)
>  {
>  	int rc;
> @@ -3126,10 +3161,10 @@ static int pmbus_init_debugfs(struct i2c_client *client,
>  	/*
>  	 * Allocate the max possible entries we need.
>  	 * 6 entries device-specific
> -	 * 10 entries page-specific
> +	 * 13 entries page-specific
>  	 */
>  	entries = devm_kcalloc(data->dev,
> -			       6 + data->info->pages * 10, sizeof(*entries),
> +			       6 + data->info->pages * 13, sizeof(*entries),
>  			       GFP_KERNEL);
>  	if (!entries)
>  		return -ENOMEM;
> @@ -3299,6 +3334,47 @@ static int pmbus_init_debugfs(struct i2c_client *client,
>  					    &entries[idx++],
>  					    &pmbus_debugfs_ops);
>  		}
> +
> +		/*
> +		 * VOUT_COMMAND - Nominal DC/DC output voltage setpoint.
> +		 */
> +		if (data->info->func[i] & PMBUS_HAVE_VOUT) {
> +			entries[idx].client = client;
> +			entries[idx].page = i;
> +			entries[idx].reg = PMBUS_VOUT_COMMAND;
> +			scnprintf(name, PMBUS_NAME_SIZE, "vout%d_command", i);
> +			debugfs_create_file(name, 0644, data->debugfs,
> +					    &entries[idx++],
> +					    &pmbus_debugfs_ops_rw_word);
> +		}
> +
> +		/*
> +		 * VOUT_MARGIN_HIGH - Margin high DC/DC converter output.
> +		 */
> +		if (data->info->func[i] & PMBUS_HAVE_VOUT) {
> +			entries[idx].client = client;
> +			entries[idx].page = i;
> +			entries[idx].reg = PMBUS_VOUT_MARGIN_HIGH;
> +			scnprintf(name, PMBUS_NAME_SIZE,
> +				  "vout%d_margin_high", i);
> +			debugfs_create_file(name, 0644, data->debugfs,
> +					    &entries[idx++],
> +					    &pmbus_debugfs_ops_rw_word);
> +		}
> +
> +		/*
> +		 * VOUT_MARGIN_LOW - Margin low DC/DC converter output.
> +		 */
> +		if (data->info->func[i] & PMBUS_HAVE_VOUT) {
> +			entries[idx].client = client;
> +			entries[idx].page = i;
> +			entries[idx].reg = PMBUS_VOUT_MARGIN_LOW;
> +			scnprintf(name, PMBUS_NAME_SIZE,
> +				  "vout%d_margin_low", i);
> +			debugfs_create_file(name, 0644, data->debugfs,
> +					    &entries[idx++],
> +					    &pmbus_debugfs_ops_rw_word);
> +		}
>  	}
>  
>  	return devm_add_action_or_reset(data->dev,