iommu/dma: Move public interfaces to linux/iommu.h

The iommu-dma layer is now mostly encapsulated by iommu_dma_ops, with
only a couple more public interfaces left pertaining to MSI integration.
Since these depend on the main IOMMU API header anyway, move their
declarations there, taking the opportunity to update the half-baked
comments to proper kerneldoc along the way.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/9cd99738f52094e6bed44bfee03fa4f288d20695.1660668998.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

arch/arm64/mm/dma-mapping.c

@@ -7,7 +7,7 @@
 #include <linux/gfp.h>
 #include <linux/cache.h>
 #include <linux/dma-map-ops.h>
-#include <linux/dma-iommu.h>
+#include <linux/iommu.h>
 #include <xen/xen.h>
 
 #include <asm/cacheflush.h>

drivers/iommu/dma-iommu.c

@@ -1633,6 +1633,13 @@ static struct iommu_dma_msi_page *iommu_dma_get_msi_page(struct device *dev,
 	return NULL;
 }
 
+/**
+ * iommu_dma_prepare_msi() - Map the MSI page in the IOMMU domain
+ * @desc: MSI descriptor, will store the MSI page
+ * @msi_addr: MSI target address to be mapped
+ *
+ * Return: 0 on success or negative error code if the mapping failed.
+ */
 int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr)
 {
 	struct device *dev = msi_desc_to_dev(desc);
@@ -1661,8 +1668,12 @@ int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr)
 	return 0;
 }
 
-void iommu_dma_compose_msi_msg(struct msi_desc *desc,
-			       struct msi_msg *msg)
+/**
+ * iommu_dma_compose_msi_msg() - Apply translation to an MSI message
+ * @desc: MSI descriptor prepared by iommu_dma_prepare_msi()
+ * @msg: MSI message containing target physical address
+ */
+void iommu_dma_compose_msi_msg(struct msi_desc *desc, struct msi_msg *msg)
 {
 	struct device *dev = msi_desc_to_dev(desc);
 	const struct iommu_domain *domain = iommu_get_domain_for_dev(dev);

drivers/irqchip/irq-gic-v2m.c

@@ -13,7 +13,7 @@
 #define pr_fmt(fmt) "GICv2m: " fmt
 
 #include <linux/acpi.h>
-#include <linux/dma-iommu.h>
+#include <linux/iommu.h>
 #include <linux/irq.h>
 #include <linux/irqdomain.h>
 #include <linux/kernel.h>

drivers/irqchip/irq-gic-v3-its.c

@@ -11,9 +11,9 @@
 #include <linux/cpu.h>
 #include <linux/crash_dump.h>
 #include <linux/delay.h>
-#include <linux/dma-iommu.h>
 #include <linux/efi.h>
 #include <linux/interrupt.h>
+#include <linux/iommu.h>
 #include <linux/iopoll.h>
 #include <linux/irqdomain.h>
 #include <linux/list.h>

drivers/irqchip/irq-gic-v3-mbi.c

@@ -6,7 +6,7 @@
 
 #define pr_fmt(fmt) "GICv3: " fmt
 
-#include <linux/dma-iommu.h>
+#include <linux/iommu.h>
 #include <linux/irq.h>
 #include <linux/irqdomain.h>
 #include <linux/kernel.h>

drivers/irqchip/irq-ls-scfg-msi.c

@@ -11,6 +11,7 @@
 #include <linux/module.h>
 #include <linux/msi.h>
 #include <linux/interrupt.h>
+#include <linux/iommu.h>
 #include <linux/irq.h>
 #include <linux/irqchip/chained_irq.h>
 #include <linux/irqdomain.h>
@@ -18,7 +19,6 @@
 #include <linux/of_pci.h>
 #include <linux/of_platform.h>
 #include <linux/spinlock.h>
-#include <linux/dma-iommu.h>
 
 #define MSI_IRQS_PER_MSIR	32
 #define MSI_MSIR_OFFSET		4

drivers/vfio/vfio_iommu_type1.c

@@ -37,7 +37,6 @@
 #include <linux/vfio.h>
 #include <linux/workqueue.h>
 #include <linux/notifier.h>
-#include <linux/dma-iommu.h>
 #include <linux/irqdomain.h>
 #include "vfio.h"
 

include/linux/dma-iommu.h

@@ -15,27 +15,10 @@
 
 /* Domain management interface for IOMMU drivers */
 int iommu_get_dma_cookie(struct iommu_domain *domain);
-int iommu_get_msi_cookie(struct iommu_domain *domain, dma_addr_t base);
 void iommu_put_dma_cookie(struct iommu_domain *domain);
 
-/* Setup call for arch DMA mapping code */
-void iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 dma_limit);
 int iommu_dma_init_fq(struct iommu_domain *domain);
 
-/* The DMA API isn't _quite_ the whole story, though... */
-/*
- * iommu_dma_prepare_msi() - Map the MSI page in the IOMMU device
- *
- * The MSI page will be stored in @desc.
- *
- * Return: 0 on success otherwise an error describing the failure.
- */
-int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr);
-
-/* Update the MSI message if required. */
-void iommu_dma_compose_msi_msg(struct msi_desc *desc,
-			       struct msi_msg *msg);
-
 void iommu_dma_get_resv_regions(struct device *dev, struct list_head *list);
 
 void iommu_dma_free_cpu_cached_iovas(unsigned int cpu,
@@ -46,15 +29,8 @@ extern bool iommu_dma_forcedac;
 #else /* CONFIG_IOMMU_DMA */
 
 struct iommu_domain;
-struct msi_desc;
-struct msi_msg;
 struct device;
 
-static inline void iommu_setup_dma_ops(struct device *dev, u64 dma_base,
-				       u64 dma_limit)
-{
-}
-
 static inline int iommu_dma_init_fq(struct iommu_domain *domain)
 {
 	return -EINVAL;
@@ -65,26 +41,10 @@ static inline int iommu_get_dma_cookie(struct iommu_domain *domain)
 	return -ENODEV;
 }
 
-static inline int iommu_get_msi_cookie(struct iommu_domain *domain, dma_addr_t base)
-{
-	return -ENODEV;
-}
-
 static inline void iommu_put_dma_cookie(struct iommu_domain *domain)
 {
 }
 
-static inline int iommu_dma_prepare_msi(struct msi_desc *desc,
-					phys_addr_t msi_addr)
-{
-	return 0;
-}
-
-static inline void iommu_dma_compose_msi_msg(struct msi_desc *desc,
-					     struct msi_msg *msg)
-{
-}
-
 static inline void iommu_dma_get_resv_regions(struct device *dev, struct list_head *list)
 {
 }

include/linux/iommu.h

@@ -1063,4 +1063,40 @@ void iommu_debugfs_setup(void);
 static inline void iommu_debugfs_setup(void) {}
 #endif
 
+#ifdef CONFIG_IOMMU_DMA
+#include <linux/msi.h>
+
+/* Setup call for arch DMA mapping code */
+void iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 dma_limit);
+
+int iommu_get_msi_cookie(struct iommu_domain *domain, dma_addr_t base);
+
+int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr);
+void iommu_dma_compose_msi_msg(struct msi_desc *desc, struct msi_msg *msg);
+
+#else /* CONFIG_IOMMU_DMA */
+
+struct msi_desc;
+struct msi_msg;
+
+static inline void iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 dma_limit)
+{
+}
+
+static inline int iommu_get_msi_cookie(struct iommu_domain *domain, dma_addr_t base)
+{
+	return -ENODEV;
+}
+
+static inline int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr)
+{
+	return 0;
+}
+
+static inline void iommu_dma_compose_msi_msg(struct msi_desc *desc, struct msi_msg *msg)
+{
+}
+
+#endif	/* CONFIG_IOMMU_DMA */
+
 #endif /* __LINUX_IOMMU_H */