[PATCH v7 09/15] ACPI: platform-msi: retrieve dev id from IORT

[Hanjun Guo]

For devices connecting to ITS, it needs dev id to identify itself, and
this dev id is represented in the IORT table in named component node
[1] for platform devices, so in this patch we will scan the IORT to
retrieve device's dev id.

For named components we know that there are always two steps
involved (second optional):

(1) Retrieve the initial id (this may well provide the final mapping)
(2) Map the id (optional if (1) represents the map type we need), this
    is needed for use cases such as NC (named component) -> SMMU -> ITS
    mappings.

we have API iort_node_get_id() for step (1) above and
iort_node_map_rid() for step (2), so create a wrapper
iort_node_map_platform_id() to retrieve the dev id.

[1]: https://static.docs.arm.com/den0049/b/DEN0049B_IO_Remapping_Table.pdf

Suggested-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
Suggested-by: Tomasz Nowicki <tn at semihalf.com>
Signed-off-by: Hanjun Guo <hanjun.guo at linaro.org>
Cc: Marc Zyngier <marc.zyngier at arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
Cc: Sinan Kaya <okaya at codeaurora.org>
Cc: Tomasz Nowicki <tn at semihalf.com>
Cc: Thomas Gleixner <tglx at linutronix.de>
---
 drivers/acpi/arm64/iort.c                     | 56 +++++++++++++++++++++++++++
 drivers/irqchip/irq-gic-v3-its-platform-msi.c |  4 +-
 include/linux/acpi_iort.h                     |  8 ++++
 3 files changed, 67 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index 069a690..95fd20b 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -30,6 +30,7 @@
 #define IORT_MSI_TYPE		(1 << ACPI_IORT_NODE_ITS_GROUP)
 #define IORT_IOMMU_TYPE		((1 << ACPI_IORT_NODE_SMMU) |	\
 				(1 << ACPI_IORT_NODE_SMMU_V3))
+#define IORT_TYPE_ANY		(IORT_MSI_TYPE | IORT_IOMMU_TYPE)
 
 struct iort_its_msi_chip {
 	struct list_head	list;
@@ -406,6 +407,34 @@ static struct acpi_iort_node *iort_node_map_id(struct acpi_iort_node *node,
 	return NULL;
 }
 
+static
+struct acpi_iort_node *iort_node_map_platform_id(struct acpi_iort_node *node,
+						 u32 *id_out, u8 type_mask,
+						 int index)
+{
+	struct acpi_iort_node *parent;
+	u32 id;
+
+	/* step 1: retrieve the initial dev id */
+	parent = iort_node_get_id(node, &id, IORT_TYPE_ANY, index);
+	if (!parent)
+		return NULL;
+
+	/*
+	 * optional step 2: map the initial dev id if its parent is not
+	 * the target type we wanted, map it again for the use cases such
+	 * as NC (named component) -> SMMU -> ITS. If the type is matched,
+	 * return the parent pointer directly.
+	 */
+	if (!(IORT_TYPE_MASK(parent->type) & type_mask))
+		parent = iort_node_map_id(parent, id, id_out, type_mask);
+	else
+		if (id_out)
+			*id_out = id;
+
+	return parent;
+}
+
 static struct acpi_iort_node *iort_find_dev_node(struct device *dev)
 {
 	struct pci_bus *pbus;
@@ -444,6 +473,33 @@ u32 iort_msi_map_rid(struct device *dev, u32 req_id)
 }
 
 /**
+ * iort_pmsi_get_dev_id() - Get the device id for a device
+ * @dev: The device for which the mapping is to be done.
+ * @dev_id: The device ID found.
+ *
+ * Returns: 0 for successful find a dev id, errors otherwise
+ */
+int iort_pmsi_get_dev_id(struct device *dev, u32 *dev_id)
+{
+	int i;
+	struct acpi_iort_node *node;
+
+	if (!iort_table)
+		return -ENODEV;
+
+	node = iort_find_dev_node(dev);
+	if (!node)
+		return -ENODEV;
+
+	for (i = 0; i < node->mapping_count; i++) {
+		if(iort_node_map_platform_id(node, dev_id, IORT_MSI_TYPE, i))
+			return 0;
+	}
+
+	return -ENODEV;
+}
+
+/**
  * iort_dev_find_its_id() - Find the ITS identifier for a device
  * @dev: The device.
  * @req_id: Device's requester ID
diff --git a/drivers/irqchip/irq-gic-v3-its-platform-msi.c b/drivers/irqchip/irq-gic-v3-its-platform-msi.c
index ebe933e..e801fc0 100644
--- a/drivers/irqchip/irq-gic-v3-its-platform-msi.c
+++ b/drivers/irqchip/irq-gic-v3-its-platform-msi.c
@@ -15,6 +15,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <linux/acpi_iort.h>
 #include <linux/device.h>
 #include <linux/msi.h>
 #include <linux/of.h>
@@ -56,7 +57,8 @@ static int its_pmsi_prepare(struct irq_domain *domain, struct device *dev,
 
 	msi_info = msi_get_domain_info(domain->parent);
 
-	ret = of_pmsi_get_dev_id(domain, dev, &dev_id);
+	ret = dev->of_node ? of_pmsi_get_dev_id(domain, dev, &dev_id) :
+		iort_pmsi_get_dev_id(dev, &dev_id);
 	if (ret)
 		return ret;
 
diff --git a/include/linux/acpi_iort.h b/include/linux/acpi_iort.h
index 77e0809..ef99fd52 100644
--- a/include/linux/acpi_iort.h
+++ b/include/linux/acpi_iort.h
@@ -33,6 +33,7 @@
 void acpi_iort_init(void);
 bool iort_node_match(u8 type);
 u32 iort_msi_map_rid(struct device *dev, u32 req_id);
+int iort_pmsi_get_dev_id(struct device *dev, u32 *dev_id);
 struct irq_domain *iort_get_device_domain(struct device *dev, u32 req_id);
 /* IOMMU interface */
 void iort_set_dma_mask(struct device *dev);
@@ -42,9 +43,16 @@ static inline void acpi_iort_init(void) { }
 static inline bool iort_node_match(u8 type) { return false; }
 static inline u32 iort_msi_map_rid(struct device *dev, u32 req_id)
 { return req_id; }
+
 static inline struct irq_domain *iort_get_device_domain(struct device *dev,
 							u32 req_id)
 { return NULL; }
+
+static inline int iort_pmsi_get_dev_id(struct device *dev, u32 *dev_id)
+{
+	return -ENODEV;
+}
+
 /* IOMMU interface */
 static inline void iort_set_dma_mask(struct device *dev) { }
 static inline
-- 
1.9.1