[PATCH v4 08/10] PCI/IDE: Report available IDE streams

[Dan Williams <dan.j.williams@intel.com>]

The limited number of link-encryption (IDE) streams that a given set of
host bridges supports is a platform specific detail. Provide
pci_ide_init_nr_streams() as a generic facility for either platform TSM
drivers, or PCI core native IDE, to report the number available streams.
After invoking pci_ide_init_nr_streams() an "available_secure_streams"
attribute appears in PCI host bridge sysfs to convey that count.

Introduce a device-type, @pci_host_bridge_type, now that both a release
method and sysfs attribute groups are being specified for all 'struct
pci_host_bridge' instances.

Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Samuel Ortiz <sameo@rivosinc.com>
Cc: Alexey Kardashevskiy <aik@amd.com>
Cc: Xu Yi lun <yilun.xu@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 .../ABI/testing/sysfs-devices-pci-host-bridge | 13 ++++
 drivers/pci/ide.c                             | 59 +++++++++++++++++++
 drivers/pci/pci.h                             |  3 +
 drivers/pci/probe.c                           | 12 +++-
 include/linux/pci.h                           |  8 +++
 5 files changed, 94 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/sysfs-devices-pci-host-bridge b/Documentation/ABI/testing/sysfs-devices-pci-host-bridge
index c67d7c30efa0..067d0879e353 100644
--- a/Documentation/ABI/testing/sysfs-devices-pci-host-bridge
+++ b/Documentation/ABI/testing/sysfs-devices-pci-host-bridge
@@ -33,3 +33,16 @@ Description:
 		resources shared by the Root Ports in a host bridge. See
 		/sys/devices/pciDDDD:BB entry for details about the DDDD:BB
 		format.
+
+What:		pciDDDD:BB/available_secure_streams
+Date:		December, 2024
+Contact:	linux-pci@vger.kernel.org
+Description:
+		(RO) When a host bridge has Root Ports that support PCIe IDE
+		(link encryption and integrity protection) there may be a
+		limited number of Selective IDE Streams that can be used for
+		establishing new end-to-end secure links. This attribute
+		decrements upon secure link setup, and increments upon secure
+		link teardown. The in-use stream count is determined by counting
+		stream symlinks.  See /sys/devices/pciDDDD:BB entry for details
+		about the DDDD:BB format.
diff --git a/drivers/pci/ide.c b/drivers/pci/ide.c
index cdc773a8b381..cafbc740a9da 100644
--- a/drivers/pci/ide.c
+++ b/drivers/pci/ide.c
@@ -513,3 +513,62 @@ void pci_ide_stream_disable(struct pci_dev *pdev, struct pci_ide *ide)
 	settings->enable = 0;
 }
 EXPORT_SYMBOL_GPL(pci_ide_stream_disable);
+
+static ssize_t available_secure_streams_show(struct device *dev,
+					     struct device_attribute *attr,
+					     char *buf)
+{
+	struct pci_host_bridge *hb = to_pci_host_bridge(dev);
+	int avail;
+
+	if (!hb->nr_ide_streams)
+		return -ENXIO;
+
+	avail = hb->nr_ide_streams -
+		bitmap_weight(hb->ide_stream_map, hb->nr_ide_streams);
+	return sysfs_emit(buf, "%d\n", avail);
+}
+static DEVICE_ATTR_RO(available_secure_streams);
+
+static struct attribute *pci_ide_attrs[] = {
+	&dev_attr_available_secure_streams.attr,
+	NULL
+};
+
+static umode_t pci_ide_attr_visible(struct kobject *kobj, struct attribute *a, int n)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct pci_host_bridge *hb = to_pci_host_bridge(dev);
+
+	if (a == &dev_attr_available_secure_streams.attr)
+		if (!hb->nr_ide_streams)
+			return 0;
+
+	return a->mode;
+}
+
+struct attribute_group pci_ide_attr_group = {
+	.attrs = pci_ide_attrs,
+	.is_visible = pci_ide_attr_visible,
+};
+
+/**
+ * pci_ide_init_nr_streams() - sets size of the pool of IDE Stream resources
+ * @hb: host bridge boundary for the stream pool
+ * @nr: number of streams
+ *
+ * Platform PCI init and/or expert test module use only. Enable IDE
+ * Stream establishment by setting the number of stream resources
+ * available at the host bridge. Platform init code must set this before
+ * the first pci_ide_stream_alloc() call.
+ *
+ * The "PCI_IDE" symbol namespace is required because this is typically
+ * a detail that is settled in early PCI init. I.e. this export is not
+ * for endpoint drivers.
+ */
+void pci_ide_init_nr_streams(struct pci_host_bridge *hb, u8 nr)
+{
+	hb->nr_ide_streams = nr;
+	sysfs_update_group(&hb->dev.kobj, &pci_ide_attr_group);
+}
+EXPORT_SYMBOL_NS_GPL(pci_ide_init_nr_streams, "PCI_IDE");
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 3b282c24dde8..8154f829d303 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -517,8 +517,11 @@ static inline void pci_doe_sysfs_teardown(struct pci_dev *pdev) { }
 
 #ifdef CONFIG_PCI_IDE
 void pci_ide_init(struct pci_dev *dev);
+extern struct attribute_group pci_ide_attr_group;
+#define PCI_IDE_ATTR_GROUP (&pci_ide_attr_group)
 #else
 static inline void pci_ide_init(struct pci_dev *dev) { }
+#define PCI_IDE_ATTR_GROUP NULL
 #endif
 
 #ifdef CONFIG_PCI_TSM
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 9ed25035a06d..a84aaad462ca 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -640,6 +640,16 @@ static void pci_release_host_bridge_dev(struct device *dev)
 	kfree(bridge);
 }
 
+static const struct attribute_group *pci_host_bridge_groups[] = {
+	PCI_IDE_ATTR_GROUP,
+	NULL
+};
+
+static const struct device_type pci_host_bridge_type = {
+	.groups = pci_host_bridge_groups,
+	.release = pci_release_host_bridge_dev,
+};
+
 static void pci_init_host_bridge(struct pci_host_bridge *bridge)
 {
 	INIT_LIST_HEAD(&bridge->windows);
@@ -659,6 +669,7 @@ static void pci_init_host_bridge(struct pci_host_bridge *bridge)
 	bridge->native_dpc = 1;
 	bridge->domain_nr = PCI_DOMAIN_NR_NOT_SET;
 	bridge->native_cxl_error = 1;
+	bridge->dev.type = &pci_host_bridge_type;
 
 	device_initialize(&bridge->dev);
 }
@@ -672,7 +683,6 @@ struct pci_host_bridge *pci_alloc_host_bridge(size_t priv)
 		return NULL;
 
 	pci_init_host_bridge(bridge);
-	bridge->dev.release = pci_release_host_bridge_dev;
 
 	return bridge;
 }
diff --git a/include/linux/pci.h b/include/linux/pci.h
index cc83ae274601..ae5f32539a91 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -664,6 +664,14 @@ void pci_set_host_bridge_release(struct pci_host_bridge *bridge,
 				 void (*release_fn)(struct pci_host_bridge *),
 				 void *release_data);
 
+#ifdef CONFIG_PCI_IDE
+void pci_ide_init_nr_streams(struct pci_host_bridge *hb, u8 nr);
+#else
+static inline void pci_ide_init_nr_streams(struct pci_host_bridge *hb, u8 nr)
+{
+}
+#endif
+
 int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge);
 
 #define PCI_REGION_FLAG_MASK	0x0fU	/* These bits of resource flags tell us the PCI region flags */
-- 
2.50.1