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Date: Mon, 13 May 2024 11:51:25 -0700
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Subject: Re: [PATCH v3] hwmon: (corsair-cpro) Add firmware and bootloader
 information
To: Marius Zachmann <mail@mariuszachmann.de>
Cc: Jean Delvare <jdelvare@suse.com>, Jonathan Corbet <corbet@lwn.net>,
 linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20240513162328.17636-3-mail@mariuszachmann.de>
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From: Guenter Roeck <linux@roeck-us.net>
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In-Reply-To: <20240513162328.17636-3-mail@mariuszachmann.de>
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On 5/13/24 09:23, Marius Zachmann wrote:
> Add support for reporting firmware and bootloader version using debugfs.
> Update documentation accordingly.
> 
> Signed-off-by: Marius Zachmann <mail@mariuszachmann.de>
> ---
> Changes in v3:
> - use different debugfs directory name for each device
> 
> Changes in v2:
> - better patch description
> - Documentation uses "Firmware version" and "Bootloader version"
> - removed conditional CONFIG_DEBUG_FS
> - get_fw_version gets called from ccp_debugfs_init
> - get_fw_version does print a hid_notice when an error occurs
>    instead of failing.
> ---
>   Documentation/hwmon/corsair-cpro.rst |  8 ++++
>   drivers/hwmon/corsair-cpro.c         | 71 ++++++++++++++++++++++++++++
>   2 files changed, 79 insertions(+)
> 
> diff --git a/Documentation/hwmon/corsair-cpro.rst b/Documentation/hwmon/corsair-cpro.rst
> index 751f95476b57..15077203a2f8 100644
> --- a/Documentation/hwmon/corsair-cpro.rst
> +++ b/Documentation/hwmon/corsair-cpro.rst
> @@ -39,3 +39,11 @@ fan[1-6]_target		Sets fan speed target rpm.
>   pwm[1-6]		Sets the fan speed. Values from 0-255. Can only be read if pwm
>   			was set directly.
>   ======================= =====================================================================
> +
> +Debugfs entries
> +---------------
> +
> +======================= ===================
> +firmware_version	Firmware version
> +bootloader_version	Bootloader version
> +======================= ===================
> diff --git a/drivers/hwmon/corsair-cpro.c b/drivers/hwmon/corsair-cpro.c
> index 3e63666a61bd..f7d321d8676e 100644
> --- a/drivers/hwmon/corsair-cpro.c
> +++ b/drivers/hwmon/corsair-cpro.c
> @@ -10,11 +10,13 @@
>   
>   #include <linux/bitops.h>
>   #include <linux/completion.h>
> +#include <linux/debugfs.h>
>   #include <linux/hid.h>
>   #include <linux/hwmon.h>
>   #include <linux/kernel.h>
>   #include <linux/module.h>
>   #include <linux/mutex.h>
> +#include <linux/seq_file.h>
>   #include <linux/slab.h>
>   #include <linux/spinlock.h>
>   #include <linux/types.h>
> @@ -28,6 +30,8 @@
>   #define LABEL_LENGTH		11
>   #define REQ_TIMEOUT		300
>   
> +#define CTL_GET_FW_VER		0x02	/* returns the firmware version in bytes 1-3 */
> +#define CTL_GET_BL_VER		0x06	/* returns the bootloader version in bytes 1-2 */
>   #define CTL_GET_TMP_CNCT	0x10	/*
>   					 * returns in bytes 1-4 for each temp sensor:
>   					 * 0 not connected
> @@ -78,6 +82,7 @@
>   struct ccp_device {
>   	struct hid_device *hdev;
>   	struct device *hwmon_dev;
> +	struct dentry *debugfs;
>   	/* For reinitializing the completion below */
>   	spinlock_t wait_input_report_lock;
>   	struct completion wait_input_report;
> @@ -88,6 +93,8 @@ struct ccp_device {
>   	DECLARE_BITMAP(temp_cnct, NUM_TEMP_SENSORS);
>   	DECLARE_BITMAP(fan_cnct, NUM_FANS);
>   	char fan_label[6][LABEL_LENGTH];
> +	u8 firmware_ver[3];
> +	u8 bootloader_ver[2];
>   };
>   
>   /* converts response error in buffer to errno */
> @@ -496,6 +503,66 @@ static int get_temp_cnct(struct ccp_device *ccp)
>   	return 0;
>   }
>   
> +/* read firmware and bootloader version */
> +static void get_fw_version(struct ccp_device *ccp)
> +{
> +	int ret;
> +
> +	ret = send_usb_cmd(ccp, CTL_GET_FW_VER, 0, 0, 0);
> +	if (ret) {
> +		hid_notice(ccp->hdev, "Failed to read firmware version.\n");

If this happens, the debugfs file should not be created, or at the very least
display something like "unavailable".

> +	} else {
> +		ccp->firmware_ver[0] = ccp->buffer[1];
> +		ccp->firmware_ver[1] = ccp->buffer[2];
> +		ccp->firmware_ver[2] = ccp->buffer[3];

That makes me wonder: What is in buffer[0] ?

> +	}
> +
> +	ret = send_usb_cmd(ccp, CTL_GET_BL_VER, 0, 0, 0);
> +	if (ret) {
> +		hid_notice(ccp->hdev, "Failed to read bootloader version.\n");

Same here.

> +	} else {
> +		ccp->bootloader_ver[0] = ccp->buffer[1];
> +		ccp->bootloader_ver[1] = ccp->buffer[2];
> +	}
> +}
> +
> +static int firmware_show(struct seq_file *seqf, void *unused)
> +{
> +	struct ccp_device *ccp = seqf->private;
> +
> +	seq_printf(seqf, "%d.%d.%d\n",
> +		   ccp->firmware_ver[0],
> +		   ccp->firmware_ver[1],
> +		   ccp->firmware_ver[2]);
> +
> +	return 0;
> +}
> +DEFINE_SHOW_ATTRIBUTE(firmware);
> +
> +static int bootloader_show(struct seq_file *seqf, void *unused)
> +{
> +	struct ccp_device *ccp = seqf->private;
> +
> +	seq_printf(seqf, "%d.%d\n",
> +		   ccp->bootloader_ver[0],
> +		   ccp->bootloader_ver[1]);
> +
> +	return 0;
> +}
> +DEFINE_SHOW_ATTRIBUTE(bootloader);
> +
> +static void ccp_debugfs_init(struct ccp_device *ccp)
> +{
> +	char name[32];
> +
> +	get_fw_version(ccp);
> +
> +	scnprintf(name, sizeof(name), "corsaircpro-%s", dev_name(&ccp->hdev->dev));
> +	ccp->debugfs = debugfs_create_dir(name, NULL);
> +	debugfs_create_file("firmware_version", 0444, ccp->debugfs, ccp, &firmware_fops);
> +	debugfs_create_file("bootloader_version", 0444, ccp->debugfs, ccp, &bootloader_fops);
> +}
> +
>   static int ccp_probe(struct hid_device *hdev, const struct hid_device_id *id)
>   {
>   	struct ccp_device *ccp;
> @@ -542,6 +609,9 @@ static int ccp_probe(struct hid_device *hdev, const struct hid_device_id *id)
>   	ret = get_fan_cnct(ccp);
>   	if (ret)
>   		goto out_hw_close;
> +
> +	ccp_debugfs_init(ccp);
> +
>   	ccp->hwmon_dev = hwmon_device_register_with_info(&hdev->dev, "corsaircpro",
>   							 ccp, &ccp_chip_info, NULL);
>   	if (IS_ERR(ccp->hwmon_dev)) {
> @@ -562,6 +632,7 @@ static void ccp_remove(struct hid_device *hdev)
>   {
>   	struct ccp_device *ccp = hid_get_drvdata(hdev);
>   
> +	debugfs_remove_recursive(ccp->debugfs);
>   	hwmon_device_unregister(ccp->hwmon_dev);
>   	hid_hw_close(hdev);
>   	hid_hw_stop(hdev);