[PATCH 0/2] uacce: add device usage sysfs interface

[PATCH 0/2] uacce: add device usage sysfs interface

[Weili Qian]

Add a read-only dev_usage sysfs attribute so userspace can query device
usage through sysfs. Patch 1 adds the attribute and the get_dev_usage
callback to the UACCE framework; patch 2 implements the callback in the
HiSilicon QM driver.

Weili Qian (2):
  uacce: add device usage sysfs interface
  crypto: hisilicon/qm - implement uacce get_dev_usage callback

 Documentation/ABI/testing/sysfs-driver-uacce |  9 ++++
 drivers/crypto/hisilicon/debugfs.c           | 17 -------
 drivers/crypto/hisilicon/qm.c                | 52 ++++++++++++++++++++
 drivers/crypto/hisilicon/qm_common.h         |  1 +
 drivers/misc/uacce/uacce.c                   | 19 +++++++
 include/linux/uacce.h                        |  5 ++
 6 files changed, 86 insertions(+), 17 deletions(-)

-- 
2.43.0

[PATCH 1/2] uacce: add device usage sysfs interface

[Weili Qian]

Userspace has no way to query the runtime usage of a UACCE
device; it can only be inferred indirectly from queue state, which is
neither accurate nor uniform across drivers.

Add a read-only dev_usage sysfs attribute and a get_dev_usage callback
in struct uacce_ops. A driver implementing the callback writes the
current usage as a percentage (0-100) string into the caller-provided
buffer and returns the number of bytes written; dev_usage_show()
appends the trailing newline. The attribute is hidden via
uacce_dev_is_visible() when the driver does not provide the callback.

The corresponding ABI entry is added to Documentation/ABI/testing/
sysfs-driver-uacce.

Signed-off-by: Weili Qian <qianweili@huawei.com>
---
 Documentation/ABI/testing/sysfs-driver-uacce |  9 +++++++++
 drivers/misc/uacce/uacce.c                   | 19 +++++++++++++++++++
 include/linux/uacce.h                        |  5 +++++
 3 files changed, 33 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-driver-uacce b/Documentation/ABI/testing/sysfs-driver-uacce
index d3f0b8f3c589..3e4af4c1e5a9 100644
--- a/Documentation/ABI/testing/sysfs-driver-uacce
+++ b/Documentation/ABI/testing/sysfs-driver-uacce
@@ -55,3 +55,12 @@ Date:           Feb 2020
 KernelVersion:  5.7
 Contact:        linux-accelerators@lists.ozlabs.org
 Description:    Size (bytes) of dus region queue file
+
+What:           /sys/class/uacce/<dev_name>/dev_usage
+Date:           Sep 2026
+KernelVersion:  7.3
+Contact:        linux-accelerators@lists.ozlabs.org
+Description:    (R) Current usage of the device, reported as a driver-defined
+                string of up to PAGE_SIZE - 1 bytes. Usage is expressed as a
+                percentage (0-100). The attribute is hidden if the driver does
+                not implement the get_dev_usage callback.
diff --git a/drivers/misc/uacce/uacce.c b/drivers/misc/uacce/uacce.c
index 45521d4a56d1..545ba35a590b 100644
--- a/drivers/misc/uacce/uacce.c
+++ b/drivers/misc/uacce/uacce.c
@@ -433,6 +433,20 @@ static ssize_t isolate_strategy_store(struct device *dev, struct device_attribut
 	return count;
 }
 
+static ssize_t dev_usage_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct uacce_device *uacce = to_uacce_device(dev);
+	int ret;
+
+	ret = uacce->ops->get_dev_usage(uacce, buf, PAGE_SIZE - 1);
+	if (ret < 0)
+		return ret;
+
+	buf[ret++] = '\n';
+
+	return ret;
+}
+
 static DEVICE_ATTR_RO(api);
 static DEVICE_ATTR_RO(flags);
 static DEVICE_ATTR_RO(available_instances);
@@ -441,6 +455,7 @@ static DEVICE_ATTR_RO(region_mmio_size);
 static DEVICE_ATTR_RO(region_dus_size);
 static DEVICE_ATTR_RO(isolate);
 static DEVICE_ATTR_RW(isolate_strategy);
+static DEVICE_ATTR_RO(dev_usage);
 
 static struct attribute *uacce_dev_attrs[] = {
 	&dev_attr_api.attr,
@@ -451,6 +466,7 @@ static struct attribute *uacce_dev_attrs[] = {
 	&dev_attr_region_dus_size.attr,
 	&dev_attr_isolate.attr,
 	&dev_attr_isolate_strategy.attr,
+	&dev_attr_dev_usage.attr,
 	NULL,
 };
 
@@ -474,6 +490,9 @@ static umode_t uacce_dev_is_visible(struct kobject *kobj,
 	if (attr == &dev_attr_isolate.attr && !uacce->ops->get_isolate_state)
 		return 0;
 
+	if (attr == &dev_attr_dev_usage.attr && !uacce->ops->get_dev_usage)
+		return 0;
+
 	return attr->mode;
 }
 
diff --git a/include/linux/uacce.h b/include/linux/uacce.h
index e290c0269944..8f0b9765e4b6 100644
--- a/include/linux/uacce.h
+++ b/include/linux/uacce.h
@@ -34,6 +34,10 @@ struct uacce_qfile_region {
  * @get_isolate_state: get the device state after set the isolate strategy
  * @isolate_err_threshold_write: stored the isolate error threshold to the device
  * @isolate_err_threshold_read: read the isolate error threshold value from the device
+ * @get_dev_usage: get the device usage. Write a string describing current
+ *                 usage as a percentage (0-100) into @buf, at most @size
+ *                 bytes, without a trailing newline. Return the number of
+ *                 bytes written on success or a negative errno on failure.
  */
 struct uacce_ops {
 	int (*get_available_instances)(struct uacce_device *uacce);
@@ -50,6 +54,7 @@ struct uacce_ops {
 	enum uacce_dev_state (*get_isolate_state)(struct uacce_device *uacce);
 	int (*isolate_err_threshold_write)(struct uacce_device *uacce, u32 num);
 	u32 (*isolate_err_threshold_read)(struct uacce_device *uacce);
+	int (*get_dev_usage)(struct uacce_device *uacce, char *buf, int size);
 };
 
 /**
-- 
2.43.0

[PATCH 2/2] crypto: hisilicon/qm - implement uacce get_dev_usage callback

[Weili Qian]

The HiSilicon QM driver does not implement the get_dev_usage callback,
so the dev_usage sysfs attribute is hidden on its UACCE devices and
userspace cannot query per-channel usage through sysfs.

Implement hisi_qm_get_dev_usage and register it in uacce_qm_ops. For
each channel the callback reads the channel-usage register and derives
the usage via the existing qm_usage_percent() helper, moved to qm.c
with a shared declaration in qm_common.h to avoid duplication.

The channel-usage registers exist only on QM_HW_V5 and later, so the
callback returns -ENODEV on older revisions.

Signed-off-by: Weili Qian <qianweili@huawei.com>
---
 drivers/crypto/hisilicon/debugfs.c   | 17 ---------
 drivers/crypto/hisilicon/qm.c        | 52 ++++++++++++++++++++++++++++
 drivers/crypto/hisilicon/qm_common.h |  1 +
 3 files changed, 53 insertions(+), 17 deletions(-)

diff --git a/drivers/crypto/hisilicon/debugfs.c b/drivers/crypto/hisilicon/debugfs.c
index 3ee6de16e3f1..83dfbe74e704 100644
--- a/drivers/crypto/hisilicon/debugfs.c
+++ b/drivers/crypto/hisilicon/debugfs.c
@@ -1040,23 +1040,6 @@ void hisi_qm_show_last_dfx_regs(struct hisi_qm *qm)
 	}
 }
 
-static int qm_usage_percent(struct hisi_qm *qm, int chan_num)
-{
-	u32 val, used_bw, total_bw;
-
-	val = readl(qm->io_base + QM_CHANNEL_USAGE_OFFSET +
-				chan_num * QM_CHANNEL_ADDR_INTRVL);
-	used_bw = lower_16_bits(val);
-	total_bw = upper_16_bits(val);
-	if (!total_bw)
-		return -EIO;
-
-	if (total_bw <= used_bw)
-		return QM_MAX_DEV_USAGE;
-
-	return (used_bw * QM_DEV_USAGE_RATE) / total_bw;
-}
-
 static int qm_usage_show(struct seq_file *s, void *unused)
 {
 	struct hisi_qm *qm = s->private;
diff --git a/drivers/crypto/hisilicon/qm.c b/drivers/crypto/hisilicon/qm.c
index c01966a4a33f..6cd1e98dd9e3 100644
--- a/drivers/crypto/hisilicon/qm.c
+++ b/drivers/crypto/hisilicon/qm.c
@@ -2884,6 +2884,57 @@ static u32 hisi_qm_isolate_threshold_read(struct uacce_device *uacce)
 	return qm->isolate_data.err_threshold;
 }
 
+int qm_usage_percent(struct hisi_qm *qm, int chan_idx)
+{
+	u32 val, used_bw, total_bw;
+
+	val = readl(qm->io_base + QM_CHANNEL_USAGE_OFFSET +
+		    chan_idx * QM_CHANNEL_ADDR_INTRVL);
+	used_bw = lower_16_bits(val);
+	total_bw = upper_16_bits(val);
+	if (!total_bw)
+		return -EIO;
+
+	if (total_bw <= used_bw)
+		return QM_MAX_DEV_USAGE;
+
+	return (used_bw * QM_DEV_USAGE_RATE) / total_bw;
+}
+
+static int hisi_qm_get_dev_usage(struct uacce_device *uacce, char *buf, int size)
+{
+	struct hisi_qm *qm = uacce->priv;
+	struct qm_channel *channel_data = &qm->channel_data;
+	const char *sep = "";
+	int ret, i, len = 0;
+
+	if (qm->ver < QM_HW_V5)
+		return -ENODEV;
+
+	ret = qm_pm_get_sync(qm);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < channel_data->channel_num; i++) {
+		ret = qm_usage_percent(qm, i);
+		if (ret < 0)
+			goto out;
+
+		if (len >= size)
+			break;
+
+		len += scnprintf(buf + len, size - len, "%s%s: %d",
+				 sep, channel_data->channel_name[i], ret);
+		sep = "\n";
+	}
+
+	ret = len;
+out:
+	qm_pm_put_sync(qm);
+
+	return ret;
+}
+
 static const struct uacce_ops uacce_qm_ops = {
 	.get_available_instances = hisi_qm_get_available_instances,
 	.get_queue = hisi_qm_uacce_get_queue,
@@ -2896,6 +2947,7 @@ static const struct uacce_ops uacce_qm_ops = {
 	.get_isolate_state = hisi_qm_get_isolate_state,
 	.isolate_err_threshold_write = hisi_qm_isolate_threshold_write,
 	.isolate_err_threshold_read = hisi_qm_isolate_threshold_read,
+	.get_dev_usage = hisi_qm_get_dev_usage,
 };
 
 static void qm_remove_uacce(struct hisi_qm *qm)
diff --git a/drivers/crypto/hisilicon/qm_common.h b/drivers/crypto/hisilicon/qm_common.h
index 0760bf55f13e..78bcf40bd851 100644
--- a/drivers/crypto/hisilicon/qm_common.h
+++ b/drivers/crypto/hisilicon/qm_common.h
@@ -75,5 +75,6 @@ struct qm_aeqc {
 int qm_set_and_get_xqc(struct hisi_qm *qm, u8 cmd, void *xqc, u32 qp_id, bool op);
 void hisi_qm_show_last_dfx_regs(struct hisi_qm *qm);
 void hisi_qm_set_algqos_init(struct hisi_qm *qm);
+int qm_usage_percent(struct hisi_qm *qm, int chan_idx);
 
 #endif
-- 
2.43.0

Re: [PATCH 1/2] uacce: add device usage sysfs interface

[Greg KH]

On Mon, Sep 21, 2026 at 03:51:30PM +0800, Weili Qian wrote:
> Userspace has no way to query the runtime usage of a UACCE
> device; it can only be inferred indirectly from queue state, which is
> neither accurate nor uniform across drivers.
> 
> Add a read-only dev_usage sysfs attribute and a get_dev_usage callback
> in struct uacce_ops. A driver implementing the callback writes the
> current usage as a percentage (0-100) string into the caller-provided
> buffer and returns the number of bytes written; dev_usage_show()
> appends the trailing newline. The attribute is hidden via
> uacce_dev_is_visible() when the driver does not provide the callback.
> 
> The corresponding ABI entry is added to Documentation/ABI/testing/
> sysfs-driver-uacce.
> 
> Signed-off-by: Weili Qian <qianweili@huawei.com>
> ---
>  Documentation/ABI/testing/sysfs-driver-uacce |  9 +++++++++
>  drivers/misc/uacce/uacce.c                   | 19 +++++++++++++++++++
>  include/linux/uacce.h                        |  5 +++++
>  3 files changed, 33 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-driver-uacce b/Documentation/ABI/testing/sysfs-driver-uacce
> index d3f0b8f3c589..3e4af4c1e5a9 100644
> --- a/Documentation/ABI/testing/sysfs-driver-uacce
> +++ b/Documentation/ABI/testing/sysfs-driver-uacce
> @@ -55,3 +55,12 @@ Date:           Feb 2020
>  KernelVersion:  5.7
>  Contact:        linux-accelerators@lists.ozlabs.org
>  Description:    Size (bytes) of dus region queue file
> +
> +What:           /sys/class/uacce/<dev_name>/dev_usage
> +Date:           Sep 2026
> +KernelVersion:  7.3

That's not going to happen here :(

> +Contact:        linux-accelerators@lists.ozlabs.org
> +Description:    (R) Current usage of the device, reported as a driver-defined
> +                string of up to PAGE_SIZE - 1 bytes. Usage is expressed as a
> +                percentage (0-100). The attribute is hidden if the driver does
> +                not implement the get_dev_usage callback.
> diff --git a/drivers/misc/uacce/uacce.c b/drivers/misc/uacce/uacce.c
> index 45521d4a56d1..545ba35a590b 100644
> --- a/drivers/misc/uacce/uacce.c
> +++ b/drivers/misc/uacce/uacce.c
> @@ -433,6 +433,20 @@ static ssize_t isolate_strategy_store(struct device *dev, struct device_attribut
>  	return count;
>  }
>  
> +static ssize_t dev_usage_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +	struct uacce_device *uacce = to_uacce_device(dev);
> +	int ret;
> +
> +	ret = uacce->ops->get_dev_usage(uacce, buf, PAGE_SIZE - 1);

Why can't you use sysfs_emit()?  That way you don't have to worry about
PAGE_SIZE, and you don't have to do:

> +	if (ret < 0)
> +		return ret;
> +
> +	buf[ret++] = '\n';

That type of thing :(

Also, you got your math wrong above :(

> +
> +	return ret;
> +}
> +
>  static DEVICE_ATTR_RO(api);
>  static DEVICE_ATTR_RO(flags);
>  static DEVICE_ATTR_RO(available_instances);
> @@ -441,6 +455,7 @@ static DEVICE_ATTR_RO(region_mmio_size);
>  static DEVICE_ATTR_RO(region_dus_size);
>  static DEVICE_ATTR_RO(isolate);
>  static DEVICE_ATTR_RW(isolate_strategy);
> +static DEVICE_ATTR_RO(dev_usage);
>  
>  static struct attribute *uacce_dev_attrs[] = {
>  	&dev_attr_api.attr,
> @@ -451,6 +466,7 @@ static struct attribute *uacce_dev_attrs[] = {
>  	&dev_attr_region_dus_size.attr,
>  	&dev_attr_isolate.attr,
>  	&dev_attr_isolate_strategy.attr,
> +	&dev_attr_dev_usage.attr,
>  	NULL,
>  };
>  
> @@ -474,6 +490,9 @@ static umode_t uacce_dev_is_visible(struct kobject *kobj,
>  	if (attr == &dev_attr_isolate.attr && !uacce->ops->get_isolate_state)
>  		return 0;
>  
> +	if (attr == &dev_attr_dev_usage.attr && !uacce->ops->get_dev_usage)
> +		return 0;
> +
>  	return attr->mode;
>  }
>  
> diff --git a/include/linux/uacce.h b/include/linux/uacce.h
> index e290c0269944..8f0b9765e4b6 100644
> --- a/include/linux/uacce.h
> +++ b/include/linux/uacce.h
> @@ -34,6 +34,10 @@ struct uacce_qfile_region {
>   * @get_isolate_state: get the device state after set the isolate strategy
>   * @isolate_err_threshold_write: stored the isolate error threshold to the device
>   * @isolate_err_threshold_read: read the isolate error threshold value from the device
> + * @get_dev_usage: get the device usage. Write a string describing current
> + *                 usage as a percentage (0-100) into @buf, at most @size
> + *                 bytes, without a trailing newline. Return the number of
> + *                 bytes written on success or a negative errno on failure.

Why the newline thing?

thanks,

greg k-h