linux-kernel - Re: [PATCH] hwmon: (pmbus/acbel-fsg032) Add firmware version debugfs attribute

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Date:   Tue, 27 Jun 2023 15:19:26 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Eddie James <eajames@...ux.ibm.com>, linux-hwmon@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, jdelvare@...e.com,
        lakshmiy@...ibm.com
Subject: Re: [PATCH] hwmon: (pmbus/acbel-fsg032) Add firmware version debugfs
 attribute

On 6/27/23 11:40, Eddie James wrote:
> Like the IBM CFFPS driver, export the PSU's firmware version to a
> debugfs attribute as reported in the manufacturer register.
> 
> Signed-off-by: Eddie James <eajames@...ux.ibm.com>
> ---
>   drivers/hwmon/pmbus/acbel-fsg032.c | 48 ++++++++++++++++++++++++++++++
>   1 file changed, 48 insertions(+)
> 
> diff --git a/drivers/hwmon/pmbus/acbel-fsg032.c b/drivers/hwmon/pmbus/acbel-fsg032.c
> index 0a0ef4ce3493..4b97f108cfe3 100644
> --- a/drivers/hwmon/pmbus/acbel-fsg032.c
> +++ b/drivers/hwmon/pmbus/acbel-fsg032.c
> @@ -3,6 +3,7 @@
>    * Copyright 2023 IBM Corp.
>    */
>   
> +#include <linux/debugfs.h>
>   #include <linux/device.h>
>   #include <linux/fs.h>
>   #include <linux/i2c.h>
> @@ -11,6 +12,52 @@
>   #include <linux/hwmon-sysfs.h>
>   #include "pmbus.h"
>   
> +#define ACBEL_MFR_FW_REVISION	0xd9
> +
> +static ssize_t acbel_fsg032_debugfs_read(struct file *file, char __user *buf, size_t count,
> +					 loff_t *ppos)
> +{
> +	struct i2c_client *client = file->private_data;
> +	char data[I2C_SMBUS_BLOCK_MAX + 2] = { 0 };
> +	char out[8];
> +	int rc;
> +	int i;
> +
> +	rc = pmbus_lock_interruptible(client);

Is that needed here ?

> +	if (rc)
> +		return rc;
> +
> +	rc = i2c_smbus_read_block_data(client, ACBEL_MFR_FW_REVISION, data);
> +	pmbus_unlock(client);
> +	if (rc < 0)
> +		return rc;
> +
> +	for (i = 0; i < rc && i < 3; ++i)
> +		snprintf(&out[i * 2], 3, "%02X", data[i]);
> +
> +	rc = i * 2;
> +	out[rc++] = '\n';
> +	out[rc++] = 0;

Any reason for not using one of the %*ph variants ?

Thanks,
Guenter

> +	return simple_read_from_buffer(buf, count, ppos, out, rc);
> +}
> +
> +static const struct file_operations acbel_debugfs_ops = {
> +	.llseek = noop_llseek,
> +	.read = acbel_fsg032_debugfs_read,
> +	.write = NULL,
> +	.open = simple_open,
> +};
> +
> +static void acbel_fsg032_init_debugfs(struct i2c_client *client)
> +{
> +	struct dentry *debugfs = pmbus_get_debugfs_dir(client);
> +
> +	if (!debugfs)
> +		return;
> +
> +	debugfs_create_file("fw_version", 0444, debugfs, client, &acbel_debugfs_ops);
> +}
> +
>   static const struct i2c_device_id acbel_fsg032_id[] = {
>   	{ "acbel_fsg032" },
>   	{}
> @@ -59,6 +106,7 @@ static int acbel_fsg032_probe(struct i2c_client *client)
>   	if (rc)
>   		return rc;
>   
> +	acbel_fsg032_init_debugfs(client);
>   	return 0;
>   }
>