DOE r1.1 replaced all occurrences of "protocol" with the term "feature"
or "Data Object Type".
PCIe r6.1 (which was published July 24) incorporated that change.
This patch renames the existing terms protocol with feature.
Signed-off-by: Alistair Francis <[email protected]>
---
v8:
- Rename prot to feat as well
v7:
- Initial patch
drivers/pci/doe.c | 88 +++++++++++++++++++++++------------------------
1 file changed, 44 insertions(+), 44 deletions(-)
diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c
index e3aab5edaf70..78ce79e031cd 100644
--- a/drivers/pci/doe.c
+++ b/drivers/pci/doe.c
@@ -43,7 +43,7 @@
*
* @pdev: PCI device this mailbox belongs to
* @cap_offset: Capability offset
- * @prots: Array of protocols supported (encoded as long values)
+ * @feats: Array of features supported (encoded as long values)
* @wq: Wait queue for work item
* @work_queue: Queue of pci_doe_work items
* @flags: Bit array of PCI_DOE_FLAG_* flags
@@ -51,14 +51,14 @@
struct pci_doe_mb {
struct pci_dev *pdev;
u16 cap_offset;
- struct xarray prots;
+ struct xarray feats;
wait_queue_head_t wq;
struct workqueue_struct *work_queue;
unsigned long flags;
};
-struct pci_doe_protocol {
+struct pci_doe_feature {
u16 vid;
u8 type;
};
@@ -66,7 +66,7 @@ struct pci_doe_protocol {
/**
* struct pci_doe_task - represents a single query/response
*
- * @prot: DOE Protocol
+ * @feat: DOE Feature
* @request_pl: The request payload
* @request_pl_sz: Size of the request payload (bytes)
* @response_pl: The response payload
@@ -78,7 +78,7 @@ struct pci_doe_protocol {
* @doe_mb: Used internally by the mailbox
*/
struct pci_doe_task {
- struct pci_doe_protocol prot;
+ struct pci_doe_feature feat;
const __le32 *request_pl;
size_t request_pl_sz;
__le32 *response_pl;
@@ -171,8 +171,8 @@ static int pci_doe_send_req(struct pci_doe_mb *doe_mb,
length = 0;
/* Write DOE Header */
- val = FIELD_PREP(PCI_DOE_DATA_OBJECT_HEADER_1_VID, task->prot.vid) |
- FIELD_PREP(PCI_DOE_DATA_OBJECT_HEADER_1_TYPE, task->prot.type);
+ val = FIELD_PREP(PCI_DOE_DATA_OBJECT_HEADER_1_VID, task->feat.vid) |
+ FIELD_PREP(PCI_DOE_DATA_OBJECT_HEADER_1_TYPE, task->feat.type);
pci_write_config_dword(pdev, offset + PCI_DOE_WRITE, val);
pci_write_config_dword(pdev, offset + PCI_DOE_WRITE,
FIELD_PREP(PCI_DOE_DATA_OBJECT_HEADER_2_LENGTH,
@@ -217,12 +217,12 @@ static int pci_doe_recv_resp(struct pci_doe_mb *doe_mb, struct pci_doe_task *tas
int i = 0;
u32 val;
- /* Read the first dword to get the protocol */
+ /* Read the first dword to get the feature */
pci_read_config_dword(pdev, offset + PCI_DOE_READ, &val);
- if ((FIELD_GET(PCI_DOE_DATA_OBJECT_HEADER_1_VID, val) != task->prot.vid) ||
- (FIELD_GET(PCI_DOE_DATA_OBJECT_HEADER_1_TYPE, val) != task->prot.type)) {
- dev_err_ratelimited(&pdev->dev, "[%x] expected [VID, Protocol] = [%04x, %02x], got [%04x, %02x]\n",
- doe_mb->cap_offset, task->prot.vid, task->prot.type,
+ if ((FIELD_GET(PCI_DOE_DATA_OBJECT_HEADER_1_VID, val) != task->feat.vid) ||
+ (FIELD_GET(PCI_DOE_DATA_OBJECT_HEADER_1_TYPE, val) != task->feat.type)) {
+ dev_err_ratelimited(&pdev->dev, "[%x] expected [VID, Feature] = [%04x, %02x], got [%04x, %02x]\n",
+ doe_mb->cap_offset, task->feat.vid, task->feat.type,
FIELD_GET(PCI_DOE_DATA_OBJECT_HEADER_1_VID, val),
FIELD_GET(PCI_DOE_DATA_OBJECT_HEADER_1_TYPE, val));
return -EIO;
@@ -384,7 +384,7 @@ static void pci_doe_task_complete(struct pci_doe_task *task)
}
static int pci_doe_discovery(struct pci_doe_mb *doe_mb, u8 *index, u16 *vid,
- u8 *protocol)
+ u8 *feature)
{
u32 request_pl = FIELD_PREP(PCI_DOE_DATA_OBJECT_DISC_REQ_3_INDEX,
*index);
@@ -404,7 +404,7 @@ static int pci_doe_discovery(struct pci_doe_mb *doe_mb, u8 *index, u16 *vid,
response_pl = le32_to_cpu(response_pl_le);
*vid = FIELD_GET(PCI_DOE_DATA_OBJECT_DISC_RSP_3_VID, response_pl);
- *protocol = FIELD_GET(PCI_DOE_DATA_OBJECT_DISC_RSP_3_PROTOCOL,
+ *feature = FIELD_GET(PCI_DOE_DATA_OBJECT_DISC_RSP_3_PROTOCOL,
response_pl);
*index = FIELD_GET(PCI_DOE_DATA_OBJECT_DISC_RSP_3_NEXT_INDEX,
response_pl);
@@ -412,12 +412,12 @@ static int pci_doe_discovery(struct pci_doe_mb *doe_mb, u8 *index, u16 *vid,
return 0;
}
-static void *pci_doe_xa_prot_entry(u16 vid, u8 prot)
+static void *pci_doe_xa_feat_entry(u16 vid, u8 type)
{
- return xa_mk_value((vid << 8) | prot);
+ return xa_mk_value((vid << 8) | type);
}
-static int pci_doe_cache_protocols(struct pci_doe_mb *doe_mb)
+static int pci_doe_cache_features(struct pci_doe_mb *doe_mb)
{
u8 index = 0;
u8 xa_idx = 0;
@@ -425,18 +425,18 @@ static int pci_doe_cache_protocols(struct pci_doe_mb *doe_mb)
do {
int rc;
u16 vid;
- u8 prot;
+ u8 type;
- rc = pci_doe_discovery(doe_mb, &index, &vid, &prot);
+ rc = pci_doe_discovery(doe_mb, &index, &vid, &type);
if (rc)
return rc;
pci_dbg(doe_mb->pdev,
- "[%x] Found protocol %d vid: %x prot: %x\n",
- doe_mb->cap_offset, xa_idx, vid, prot);
+ "[%x] Found feature %d vid: %x type: %x\n",
+ doe_mb->cap_offset, xa_idx, vid, type);
- rc = xa_insert(&doe_mb->prots, xa_idx++,
- pci_doe_xa_prot_entry(vid, prot), GFP_KERNEL);
+ rc = xa_insert(&doe_mb->feats, xa_idx++,
+ pci_doe_xa_feat_entry(vid, type), GFP_KERNEL);
if (rc)
return rc;
} while (index);
@@ -460,7 +460,7 @@ static void pci_doe_cancel_tasks(struct pci_doe_mb *doe_mb)
* @pdev: PCI device to create the DOE mailbox for
* @cap_offset: Offset of the DOE mailbox
*
- * Create a single mailbox object to manage the mailbox protocol at the
+ * Create a single mailbox object to manage the mailbox feature at the
* cap_offset specified.
*
* RETURNS: created mailbox object on success
@@ -479,7 +479,7 @@ static struct pci_doe_mb *pci_doe_create_mb(struct pci_dev *pdev,
doe_mb->pdev = pdev;
doe_mb->cap_offset = cap_offset;
init_waitqueue_head(&doe_mb->wq);
- xa_init(&doe_mb->prots);
+ xa_init(&doe_mb->feats);
doe_mb->work_queue = alloc_ordered_workqueue("%s %s DOE [%x]", 0,
dev_bus_name(&pdev->dev),
@@ -502,11 +502,11 @@ static struct pci_doe_mb *pci_doe_create_mb(struct pci_dev *pdev,
/*
* The state machine and the mailbox should be in sync now;
- * Use the mailbox to query protocols.
+ * Use the mailbox to query features.
*/
- rc = pci_doe_cache_protocols(doe_mb);
+ rc = pci_doe_cache_features(doe_mb);
if (rc) {
- pci_err(pdev, "[%x] failed to cache protocols : %d\n",
+ pci_err(pdev, "[%x] failed to cache features : %d\n",
doe_mb->cap_offset, rc);
goto err_cancel;
}
@@ -515,7 +515,7 @@ static struct pci_doe_mb *pci_doe_create_mb(struct pci_dev *pdev,
err_cancel:
pci_doe_cancel_tasks(doe_mb);
- xa_destroy(&doe_mb->prots);
+ xa_destroy(&doe_mb->feats);
err_destroy_wq:
destroy_workqueue(doe_mb->work_queue);
err_free:
@@ -533,31 +533,31 @@ static struct pci_doe_mb *pci_doe_create_mb(struct pci_dev *pdev,
static void pci_doe_destroy_mb(struct pci_doe_mb *doe_mb)
{
pci_doe_cancel_tasks(doe_mb);
- xa_destroy(&doe_mb->prots);
+ xa_destroy(&doe_mb->feats);
destroy_workqueue(doe_mb->work_queue);
kfree(doe_mb);
}
/**
- * pci_doe_supports_prot() - Return if the DOE instance supports the given
- * protocol
+ * pci_doe_supports_feat() - Return if the DOE instance supports the given
+ * feature
* @doe_mb: DOE mailbox capability to query
- * @vid: Protocol Vendor ID
- * @type: Protocol type
+ * @vid: Feature Vendor ID
+ * @type: Feature type
*
- * RETURNS: True if the DOE mailbox supports the protocol specified
+ * RETURNS: True if the DOE mailbox supports the feature specified
*/
-static bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type)
+static bool pci_doe_supports_feat(struct pci_doe_mb *doe_mb, u16 vid, u8 type)
{
unsigned long index;
void *entry;
- /* The discovery protocol must always be supported */
+ /* The discovery feature must always be supported */
if (vid == PCI_VENDOR_ID_PCI_SIG && type == PCI_DOE_PROTOCOL_DISCOVERY)
return true;
- xa_for_each(&doe_mb->prots, index, entry)
- if (entry == pci_doe_xa_prot_entry(vid, type))
+ xa_for_each(&doe_mb->feats, index, entry)
+ if (entry == pci_doe_xa_feat_entry(vid, type))
return true;
return false;
@@ -585,7 +585,7 @@ static bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type)
static int pci_doe_submit_task(struct pci_doe_mb *doe_mb,
struct pci_doe_task *task)
{
- if (!pci_doe_supports_prot(doe_mb, task->prot.vid, task->prot.type))
+ if (!pci_doe_supports_feat(doe_mb, task->feat.vid, task->feat.type))
return -EINVAL;
if (test_bit(PCI_DOE_FLAG_DEAD, &doe_mb->flags))
@@ -631,8 +631,8 @@ int pci_doe(struct pci_doe_mb *doe_mb, u16 vendor, u8 type,
{
DECLARE_COMPLETION_ONSTACK(c);
struct pci_doe_task task = {
- .prot.vid = vendor,
- .prot.type = type,
+ .feat.vid = vendor,
+ .feat.type = type,
.request_pl = request,
.request_pl_sz = request_sz,
.response_pl = response,
@@ -659,7 +659,7 @@ EXPORT_SYMBOL_GPL(pci_doe);
* @vendor: Vendor ID
* @type: Data Object Type
*
- * Find first DOE mailbox of a PCI device which supports the given protocol.
+ * Find first DOE mailbox of a PCI device which supports the given feature.
*
* RETURNS: Pointer to the DOE mailbox or NULL if none was found.
*/
@@ -670,7 +670,7 @@ struct pci_doe_mb *pci_find_doe_mailbox(struct pci_dev *pdev, u16 vendor,
unsigned long index;
xa_for_each(&pdev->doe_mbs, index, doe_mb)
- if (pci_doe_supports_prot(doe_mb, vendor, type))
+ if (pci_doe_supports_feat(doe_mb, vendor, type))
return doe_mb;
return NULL;
--
2.41.0
PCIe devices (not CXL) can support DOE as well, so allow DOE to be
enabled even if CXL isn't.
Signed-off-by: Alistair Francis <[email protected]>
Reviewed-by: Jonathan Cameron <[email protected]>
---
v8:
- No changes
v7:
- Initial patch
drivers/pci/Kconfig | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
index e9ae66cc4189..672a1f5178c6 100644
--- a/drivers/pci/Kconfig
+++ b/drivers/pci/Kconfig
@@ -117,7 +117,10 @@ config PCI_ATS
bool
config PCI_DOE
- bool
+ bool "Enable PCI Data Object Exchange (DOE) support"
+ help
+ Say Y here if you want be able to communicate with PCIe DOE
+ mailboxes.
config PCI_ECAM
bool
--
2.41.0
The PCIe 6 specification added support for the Data Object Exchange (DOE).
When DOE is supported the Discovery Data Object Protocol must be
implemented. The protocol allows a requester to obtain information about
the other DOE features supported by the device.
The kernel is already querying the DOE features supported and cacheing
the values. This patch exposes the values via sysfs. This will allow
userspace to determine which DOE features are supported by the PCIe
device.
By exposing the information to userspace tools like lspci can relay the
information to users. By listing all of the supported features we can
allow userspace to parse and support the list, which might include
vendor specific features as well as yet to be supported features.
Signed-off-by: Alistair Francis <[email protected]>
---
v8:
- Inlucde an example in the docs
- Fixup removing a file that wasn't added
- Remove a blank line
v7:
- Fixup the #ifdefs to keep the test robot happy
v6:
- Use "feature" instead of protocol
- Don't use any devm_* functions
- Add two more patches to the series
v5:
- Return the file name as the file contents
- Code cleanups and simplifications
v4:
- Fixup typos in the documentation
- Make it clear that the file names contain the information
- Small code cleanups
- Remove most #ifdefs
- Remove extra NULL assignment
v3:
- Expose each DOE feature as a separate file
v2:
- Add documentation
- Code cleanups
This patch will create a doe_features directory for all
PCIe devies. This should be fixed by a pending sysfs fixup
patch.
Documentation/ABI/testing/sysfs-bus-pci | 23 +++++
drivers/pci/doe.c | 112 ++++++++++++++++++++++++
drivers/pci/pci-sysfs.c | 10 +++
drivers/pci/pci.h | 3 +
include/linux/pci-doe.h | 1 +
5 files changed, 149 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
index ecf47559f495..b52bb82a771e 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci
+++ b/Documentation/ABI/testing/sysfs-bus-pci
@@ -500,3 +500,26 @@ Description:
console drivers from the device. Raw users of pci-sysfs
resourceN attributes must be terminated prior to resizing.
Success of the resizing operation is not guaranteed.
+
+What: /sys/bus/pci/devices/.../doe_features
+Date: August 2023
+Contact: Linux PCI developers <[email protected]>
+Description:
+ This directory contains a list of the supported
+ Data Object Exchange (DOE) features. The feature values are in
+ the file name. The contents of each file are the same as the
+ name.
+
+ The value comes from the device and specifies the vendor and
+ data object type supported. The lower byte is the data object
+ type and the next two bytes are the vendor ID.
+
+ As all DOE devices must support the DOE discovery protocol, if
+ DOE is supported you will at least see this file, with this
+ contents
+
+ # cat doe_features/0x0001:00
+ 0x0001:00
+
+ If the device supports other protocols you will see other files
+ as well.
diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c
index 78ce79e031cd..30826462d167 100644
--- a/drivers/pci/doe.c
+++ b/drivers/pci/doe.c
@@ -47,6 +47,7 @@
* @wq: Wait queue for work item
* @work_queue: Queue of pci_doe_work items
* @flags: Bit array of PCI_DOE_FLAG_* flags
+ * @sysfs_attrs: Array of sysfs device attributes
*/
struct pci_doe_mb {
struct pci_dev *pdev;
@@ -56,6 +57,10 @@ struct pci_doe_mb {
wait_queue_head_t wq;
struct workqueue_struct *work_queue;
unsigned long flags;
+
+#ifdef CONFIG_SYSFS
+ struct device_attribute *sysfs_attrs;
+#endif
};
struct pci_doe_feature {
@@ -92,6 +97,113 @@ struct pci_doe_task {
struct pci_doe_mb *doe_mb;
};
+#ifdef CONFIG_SYSFS
+static umode_t pci_doe_sysfs_attr_is_visible(struct kobject *kobj,
+ struct attribute *a, int n)
+{
+ struct pci_dev *pdev = to_pci_dev(kobj_to_dev(kobj));
+ struct pci_doe_mb *doe_mb;
+ unsigned long index, j;
+ void *entry;
+
+ xa_for_each(&pdev->doe_mbs, index, doe_mb) {
+ xa_for_each(&doe_mb->feats, j, entry)
+ return a->mode;
+ }
+
+ return 0;
+}
+
+static struct attribute *pci_dev_doe_feature_attrs[] = {
+ NULL,
+};
+
+const struct attribute_group pci_dev_doe_feature_group = {
+ .name = "doe_features",
+ .attrs = pci_dev_doe_feature_attrs,
+ .is_visible = pci_doe_sysfs_attr_is_visible,
+};
+
+static ssize_t pci_doe_sysfs_feature_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ return sysfs_emit(buf, "%s\n", attr->attr.name);
+}
+
+static int pci_doe_sysfs_feature_supports(struct pci_dev *pdev,
+ struct pci_doe_mb *doe_mb)
+{
+ struct device *dev = &pdev->dev;
+ struct device_attribute *attrs;
+ unsigned long num_features = 0;
+ unsigned long vid, type;
+ unsigned long i;
+ void *entry;
+ int ret;
+
+ xa_for_each(&doe_mb->feats, i, entry)
+ num_features++;
+
+ attrs = kcalloc(num_features, sizeof(*attrs), GFP_KERNEL);
+ if (!attrs)
+ return -ENOMEM;
+
+ doe_mb->sysfs_attrs = attrs;
+ xa_for_each(&doe_mb->feats, i, entry) {
+ sysfs_attr_init(&attrs[i].attr);
+ vid = xa_to_value(entry) >> 8;
+ type = xa_to_value(entry) & 0xFF;
+ attrs[i].attr.name = kasprintf(GFP_KERNEL,
+ "0x%04lX:%02lX", vid, type);
+ if (!attrs[i].attr.name) {
+ ret = -ENOMEM;
+ goto fail;
+ }
+
+ attrs[i].attr.mode = 0444;
+ attrs[i].show = pci_doe_sysfs_feature_show;
+
+ ret = sysfs_add_file_to_group(&dev->kobj, &attrs[i].attr,
+ pci_dev_doe_feature_group.name);
+ if (ret) {
+ attrs[i].show = NULL;
+ goto fail;
+ }
+ }
+
+ return 0;
+
+fail:
+ doe_mb->sysfs_attrs = NULL;
+ xa_for_each(&doe_mb->feats, i, entry) {
+ if (attrs[i].show)
+ sysfs_remove_file_from_group(&dev->kobj, &attrs[i].attr,
+ pci_dev_doe_feature_group.name);
+ kfree(attrs[i].attr.name);
+ }
+
+ kfree(attrs);
+
+ return ret;
+}
+
+int doe_sysfs_init(struct pci_dev *pdev)
+{
+ struct pci_doe_mb *doe_mb;
+ unsigned long index;
+ int ret;
+
+ xa_for_each(&pdev->doe_mbs, index, doe_mb) {
+ ret = pci_doe_sysfs_feature_supports(pdev, doe_mb);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+#endif
+
static int pci_doe_wait(struct pci_doe_mb *doe_mb, unsigned long timeout)
{
if (wait_event_timeout(doe_mb->wq,
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index d9eede2dbc0e..01bbd1f1cb9b 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -16,6 +16,7 @@
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/pci.h>
+#include <linux/pci-doe.h>
#include <linux/stat.h>
#include <linux/export.h>
#include <linux/topology.h>
@@ -1230,6 +1231,12 @@ static int pci_create_resource_files(struct pci_dev *pdev)
int i;
int retval;
+ if (IS_ENABLED(CONFIG_PCI_DOE)) {
+ retval = doe_sysfs_init(pdev);
+ if (retval)
+ return retval;
+ }
+
/* Expose the PCI resources from this device as files */
for (i = 0; i < PCI_STD_NUM_BARS; i++) {
@@ -1655,6 +1662,9 @@ static const struct attribute_group *pci_dev_attr_groups[] = {
#endif
#ifdef CONFIG_PCIEASPM
&aspm_ctrl_attr_group,
+#endif
+#ifdef CONFIG_PCI_DOE
+ &pci_dev_doe_feature_group,
#endif
NULL,
};
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 39a8932dc340..b85dd83ddfcb 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -186,6 +186,9 @@ extern const struct attribute_group *pci_dev_groups[];
extern const struct attribute_group *pcibus_groups[];
extern const struct device_type pci_dev_type;
extern const struct attribute_group *pci_bus_groups[];
+#ifdef CONFIG_SYSFS
+extern const struct attribute_group pci_dev_doe_feature_group;
+#endif
extern unsigned long pci_hotplug_io_size;
extern unsigned long pci_hotplug_mmio_size;
diff --git a/include/linux/pci-doe.h b/include/linux/pci-doe.h
index 1f14aed4354b..4cc13d9ccb50 100644
--- a/include/linux/pci-doe.h
+++ b/include/linux/pci-doe.h
@@ -22,4 +22,5 @@ int pci_doe(struct pci_doe_mb *doe_mb, u16 vendor, u8 type,
const void *request, size_t request_sz,
void *response, size_t response_sz);
+int doe_sysfs_init(struct pci_dev *pci_dev);
#endif
--
2.41.0
On Thu, Sep 21, 2023 at 03:55:29PM +1000, Alistair Francis wrote:
> DOE r1.1 replaced all occurrences of "protocol" with the term "feature"
> or "Data Object Type".
>
> PCIe r6.1 (which was published July 24) incorporated that change.
>
> This patch renames the existing terms protocol with feature.
Imperative mood is generally preferred instead of "This patch", i.e.:
"Rename the exising..."
Could you also rename PCI_DOE_DATA_OBJECT_DISC_RSP_3_PROTOCOL
to PCI_DOE_DATA_OBJECT_DISC_RSP_3_TYPE (per PCIe r6.1 Table 6-31,
both in drivers/pci/doe.c and include/uapi/linux/pci_regs.h).
Likewise PCI_DOE_PROTOCOL_DISCOVERY to PCI_DOE_FEATURE_DISCOVERY
(per PCIe r6.1 sec 6.30.1.1, only in drivers/pci/doe.c)?
With that addressed,
Reviewed-by: Lukas Wunner <[email protected]>
Thanks!
Lukas
On Thu, Sep 21, 2023 at 03:55:30PM +1000, Alistair Francis wrote:
> The PCIe 6 specification added support for the Data Object Exchange (DOE).
> When DOE is supported the Discovery Data Object Protocol must be
"... the DOE Discovery *Feature* must be implemented per PCIe r6.1
sec 6.30.1.1"
> implemented. The protocol allows a requester to obtain information about
> the other DOE features supported by the device.
>
> The kernel is already querying the DOE features supported and cacheing
> the values. This patch exposes the values via sysfs. This will allow
Instead of "This patch ...", prefer imperative mood, i.e.:
"Expose the values in sysfs to allow user space to ..."
> --- a/Documentation/ABI/testing/sysfs-bus-pci
> +++ b/Documentation/ABI/testing/sysfs-bus-pci
> @@ -500,3 +500,26 @@ Description:
> console drivers from the device. Raw users of pci-sysfs
> resourceN attributes must be terminated prior to resizing.
> Success of the resizing operation is not guaranteed.
> +
> +What: /sys/bus/pci/devices/.../doe_features
> +Date: August 2023
Date says August but patch submission is from September.
> --- a/drivers/pci/doe.c
> +++ b/drivers/pci/doe.c
> @@ -47,6 +47,7 @@
> * @wq: Wait queue for work item
> * @work_queue: Queue of pci_doe_work items
> * @flags: Bit array of PCI_DOE_FLAG_* flags
> + * @sysfs_attrs: Array of sysfs device attributes
What's the purpose of this pointer? It's set in
pci_doe_sysfs_feature_supports() but never used for anything.
I'm guessing that you meant to use it to tear down the added attributes
on device removal, but that's missing in the patch.
The attributes are added with sysfs_add_file_to_group(), but it seems
to me they're not automatically removed by sysfs_remove_groups() on
device teardown. Am I missing something?
> +static int pci_doe_sysfs_feature_supports(struct pci_dev *pdev,
> + struct pci_doe_mb *doe_mb)
I don't quite understand the meaning of the function name:
It sounds as if its purpose is to determine whether a feature
is supported. Maybe something like pci_doe_sysfs_add_features()
instead?
> + doe_mb->sysfs_attrs = attrs;
Set this after the xa_for_each() loop to avoid having to reset it
to NULL on error.
> + attrs[i].show = pci_doe_sysfs_feature_show;
> +
> + ret = sysfs_add_file_to_group(&dev->kobj, &attrs[i].attr,
> + pci_dev_doe_feature_group.name);
> + if (ret) {
> + attrs[i].show = NULL;
> + goto fail;
> + }
The purpose of resetting attrs[i].show to NULL in the error path
seems to be that you want to skip over features which haven't
been created as attributes yet.
It seems more straightforward to just iterate over the elements
in attrs[] until you reach one whose mode is 0.
Alternatively, use xa_for_each_range(&doe_mb->feats, i, entry, 0, i - 1).
> +int doe_sysfs_init(struct pci_dev *pdev)
Rename to pci_doe_sysfs_init() for consistency.
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -186,6 +186,9 @@ extern const struct attribute_group *pci_dev_groups[];
> extern const struct attribute_group *pcibus_groups[];
> extern const struct device_type pci_dev_type;
> extern const struct attribute_group *pci_bus_groups[];
> +#ifdef CONFIG_SYSFS
> +extern const struct attribute_group pci_dev_doe_feature_group;
> +#endif
No #ifdef necessary.
Thanks,
Lukas
On Mon, Oct 2, 2023 at 3:53 AM Lukas Wunner <[email protected]> wrote:
>
> On Thu, Sep 21, 2023 at 03:55:30PM +1000, Alistair Francis wrote:
> > The PCIe 6 specification added support for the Data Object Exchange (DOE).
> > When DOE is supported the Discovery Data Object Protocol must be
>
> "... the DOE Discovery *Feature* must be implemented per PCIe r6.1
> sec 6.30.1.1"
>
>
> > implemented. The protocol allows a requester to obtain information about
> > the other DOE features supported by the device.
> >
> > The kernel is already querying the DOE features supported and cacheing
> > the values. This patch exposes the values via sysfs. This will allow
>
> Instead of "This patch ...", prefer imperative mood, i.e.:
> "Expose the values in sysfs to allow user space to ..."
>
>
> > --- a/Documentation/ABI/testing/sysfs-bus-pci
> > +++ b/Documentation/ABI/testing/sysfs-bus-pci
> > @@ -500,3 +500,26 @@ Description:
> > console drivers from the device. Raw users of pci-sysfs
> > resourceN attributes must be terminated prior to resizing.
> > Success of the resizing operation is not guaranteed.
> > +
> > +What: /sys/bus/pci/devices/.../doe_features
> > +Date: August 2023
>
> Date says August but patch submission is from September.
>
>
> > --- a/drivers/pci/doe.c
> > +++ b/drivers/pci/doe.c
> > @@ -47,6 +47,7 @@
> > * @wq: Wait queue for work item
> > * @work_queue: Queue of pci_doe_work items
> > * @flags: Bit array of PCI_DOE_FLAG_* flags
> > + * @sysfs_attrs: Array of sysfs device attributes
>
> What's the purpose of this pointer? It's set in
> pci_doe_sysfs_feature_supports() but never used for anything.
>
> I'm guessing that you meant to use it to tear down the added attributes
> on device removal, but that's missing in the patch.
Yeah, the tear down got lost in one of the revisions. I have added it
back and reworked the patch to use the teardown.
>
> The attributes are added with sysfs_add_file_to_group(), but it seems
> to me they're not automatically removed by sysfs_remove_groups() on
> device teardown. Am I missing something?
>
>
> > +static int pci_doe_sysfs_feature_supports(struct pci_dev *pdev,
> > + struct pci_doe_mb *doe_mb)
>
> I don't quite understand the meaning of the function name:
> It sounds as if its purpose is to determine whether a feature
> is supported. Maybe something like pci_doe_sysfs_add_features()
> instead?
I changed it to pci_doe_sysfs_feature_populate() which should be clear
and matches some similar functions in the kernel.
Alistair
>
>
> > + doe_mb->sysfs_attrs = attrs;
>
> Set this after the xa_for_each() loop to avoid having to reset it
> to NULL on error.
>
>
> > + attrs[i].show = pci_doe_sysfs_feature_show;
> > +
> > + ret = sysfs_add_file_to_group(&dev->kobj, &attrs[i].attr,
> > + pci_dev_doe_feature_group.name);
> > + if (ret) {
> > + attrs[i].show = NULL;
> > + goto fail;
> > + }
>
> The purpose of resetting attrs[i].show to NULL in the error path
> seems to be that you want to skip over features which haven't
> been created as attributes yet.
>
> It seems more straightforward to just iterate over the elements
> in attrs[] until you reach one whose mode is 0.
>
> Alternatively, use xa_for_each_range(&doe_mb->feats, i, entry, 0, i - 1).
>
>
> > +int doe_sysfs_init(struct pci_dev *pdev)
>
> Rename to pci_doe_sysfs_init() for consistency.
>
>
> > --- a/drivers/pci/pci.h
> > +++ b/drivers/pci/pci.h
> > @@ -186,6 +186,9 @@ extern const struct attribute_group *pci_dev_groups[];
> > extern const struct attribute_group *pcibus_groups[];
> > extern const struct device_type pci_dev_type;
> > extern const struct attribute_group *pci_bus_groups[];
> > +#ifdef CONFIG_SYSFS
> > +extern const struct attribute_group pci_dev_doe_feature_group;
> > +#endif
>
> No #ifdef necessary.
>
> Thanks,
>
> Lukas