[PATCH v12 4/8] iommu/msi-iommu: initialization

[Eric Auger]

iommu_get/put_msi_cookie allocates/frees the resource used to store
and ref count the MSI doorbell mappings. iommu_msi_set_aperture
initializes the iova domain used for MSI IOVA allocation and sets the
iommu domain's msi geometry.

The implementation relies on dma-iommu API and iova API.

New msi functions are fully implemented if CONFIG_IOMMU_MSI is set.

Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>

---
v11 -> v12:
- handle allocation failure in iommu_get_msi_cookie

v10:
- split error management in iommu_msi_set_aperture

v9:
- remove is_aperture_set and use iommu_domain_msi_aperture_valid helper
  instead
- set iommu domain's msi geometry

v8:
- new design where msi-iommu relies on dma-iommu
- remove the iommu_domain * from the doorbell_mapping struct
- added is_aperture_set

v7:
- fix locking
- add iova_cache_get/put
- static inline functions when CONFIG_IOMMU_DMA_RESERVED is not set
- introduce struct reserved_iova_domain to encapsulate prot info &
  add prot parameter in alloc_reserved_iova_domain

v5 -> v6:
- use spin lock instead of mutex

v3 -> v4:
- formerly in "iommu/arm-smmu: implement alloc/free_reserved_iova_domain" &
  "iommu: add alloc/free_reserved_iova_domain"

v2 -> v3:
- remove iommu_alloc_reserved_iova_domain & iommu_free_reserved_iova_domain
  static implementation in case CONFIG_IOMMU_API is not set

v1 -> v2:
- moved from vfio API to IOMMU API
---
 drivers/iommu/Kconfig     |   7 ++++
 drivers/iommu/Makefile    |   1 +
 drivers/iommu/msi-iommu.c | 104 ++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/msi-iommu.h |  65 +++++++++++++++++++++++++++++
 4 files changed, 177 insertions(+)
 create mode 100644 drivers/iommu/msi-iommu.c
 create mode 100644 include/linux/msi-iommu.h

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index ad08603..5ea1610 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -74,6 +74,11 @@ config IOMMU_DMA
 	select IOMMU_IOVA
 	select NEED_SG_DMA_LENGTH
 
+# IOMMU MSI mapping
+config IOMMU_MSI
+	bool
+	select IOMMU_DMA
+
 config FSL_PAMU
 	bool "Freescale IOMMU support"
 	depends on PPC_E500MC || (COMPILE_TEST && PPC)
@@ -296,6 +301,7 @@ config SPAPR_TCE_IOMMU
 config ARM_SMMU
 	bool "ARM Ltd. System MMU (SMMU) Support"
 	depends on (ARM64 || ARM) && MMU
+	select IOMMU_MSI
 	select IOMMU_API
 	select IOMMU_IO_PGTABLE_LPAE
 	select ARM_DMA_USE_IOMMU if ARM
@@ -309,6 +315,7 @@ config ARM_SMMU
 config ARM_SMMU_V3
 	bool "ARM Ltd. System MMU Version 3 (SMMUv3) Support"
 	depends on ARM64 && PCI
+	select IOMMU_MSI
 	select IOMMU_API
 	select IOMMU_IO_PGTABLE_LPAE
 	select GENERIC_MSI_IRQ_DOMAIN
diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index c6edb31..a381e66 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -2,6 +2,7 @@ obj-$(CONFIG_IOMMU_API) += iommu.o
 obj-$(CONFIG_IOMMU_API) += iommu-traces.o
 obj-$(CONFIG_IOMMU_API) += iommu-sysfs.o
 obj-$(CONFIG_IOMMU_DMA) += dma-iommu.o
+obj-$(CONFIG_IOMMU_MSI) += msi-iommu.o
 obj-$(CONFIG_IOMMU_IO_PGTABLE) += io-pgtable.o
 obj-$(CONFIG_IOMMU_IO_PGTABLE_ARMV7S) += io-pgtable-arm-v7s.o
 obj-$(CONFIG_IOMMU_IO_PGTABLE_LPAE) += io-pgtable-arm.o
diff --git a/drivers/iommu/msi-iommu.c b/drivers/iommu/msi-iommu.c
new file mode 100644
index 0000000..26aa502f
--- /dev/null
+++ b/drivers/iommu/msi-iommu.c
@@ -0,0 +1,104 @@
+/*
+ * Reserved IOVA Management
+ *
+ * Copyright (c) 2015 Linaro Ltd.
+ *              www.linaro.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/iommu.h>
+#include <linux/dma-iommu.h>
+#include <linux/msi-iommu.h>
+#include <linux/spinlock.h>
+#include <linux/iova.h>
+
+struct doorbell_mapping {
+	struct kref		kref;
+	struct list_head	next;
+	phys_addr_t		addr;
+	dma_addr_t		iova;
+	size_t			size;
+};
+
+struct doorbell_mapping_info {
+	struct list_head list; /* list of doorbell mapping entries */
+	spinlock_t lock;
+};
+
+int iommu_get_msi_cookie(struct iommu_domain *domain)
+{
+	struct doorbell_mapping_info *dmi;
+	int ret;
+
+	if (domain->msi_cookie || domain->iova_cookie)
+		return -EINVAL;
+
+	ret = iommu_get_dma_cookie(domain);
+	if (ret)
+		return ret;
+
+	dmi = kzalloc(sizeof(*dmi), GFP_KERNEL);
+	if (!dmi) {
+		iommu_put_dma_cookie(domain);
+		return -ENOMEM;
+	}
+
+	INIT_LIST_HEAD(&dmi->list);
+	spin_lock_init(&dmi->lock);
+	iova_cache_get();
+
+	domain->msi_cookie = dmi;
+
+	return 0;
+}
+EXPORT_SYMBOL(iommu_get_msi_cookie);
+
+void iommu_put_msi_cookie(struct iommu_domain *domain)
+{
+	struct doorbell_mapping_info *dmi = domain->msi_cookie;
+
+	if (!dmi)
+		return;
+
+	domain->msi_cookie = NULL;
+
+	WARN_ON(!list_empty(&dmi->list));
+
+	kfree(dmi);
+	iommu_put_dma_cookie(domain);
+	iova_cache_put();
+}
+EXPORT_SYMBOL(iommu_put_msi_cookie);
+
+int iommu_msi_set_aperture(struct iommu_domain *domain,
+			   dma_addr_t start, dma_addr_t end)
+{
+	struct doorbell_mapping_info *dmi = domain->msi_cookie;
+	int ret;
+
+	if (!dmi)
+		return -ENODEV;
+
+	if (iommu_domain_msi_aperture_valid(domain))
+		return -EINVAL;
+
+	ret = iommu_dma_init_domain(domain, start, end - start + 1);
+
+	if (!ret) {
+		domain->msi_geometry.aperture_start = start;
+		domain->msi_geometry.aperture_end = end;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iommu_msi_set_aperture);
+
diff --git a/include/linux/msi-iommu.h b/include/linux/msi-iommu.h
new file mode 100644
index 0000000..fe5859a
--- /dev/null
+++ b/include/linux/msi-iommu.h
@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2015 Linaro Ltd.
+ *              www.linaro.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+#ifndef __MSI_IOMMU_H
+#define __MSI_IOMMU_H
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+
+struct iommu_domain;
+
+#ifdef CONFIG_IOMMU_MSI
+
+/**
+ * iommu_get_msi_cookie - Acquire MSI mapping resources for a domain
+ * @domain: IOMMU domain to prepare for MSI mapping
+ *
+ * IOMMU drivers which require MSI mapping should normally call this
+ * from their domain_alloc callback when domain->type ==
+ * IOMMU_DOMAIN_UNMANAGED.
+ */
+int iommu_get_msi_cookie(struct iommu_domain *domain);
+
+/**
+ * iommu_put_msi_cookie - Release a domain's MSI mapping resources
+ * @domain: IOMMU domain previously prepared by iommu_get_msi_cookie()
+ *
+ * IOMMU drivers requesting MSI mapping should normally call this from
+ * their domain_free callback.
+ */
+void iommu_put_msi_cookie(struct iommu_domain *domain);
+
+/**
+ * iommu_msi_set_aperture - allocate the msi iova domain
+ * according to the specified start/end IOVAs
+ *
+ * @domain: iommu domain handle
+ * @start: MSI iova start address
+ * @end: MSI iova end address
+ */
+int iommu_msi_set_aperture(struct iommu_domain *domain,
+			   dma_addr_t start, dma_addr_t end);
+
+#else
+
+static inline int
+iommu_msi_set_aperture(struct iommu_domain *domain,
+		       dma_addr_t start, dma_addr_t end)
+{
+	return -ENOENT;
+}
+
+#endif	/* CONFIG_IOMMU_MSI */
+#endif	/* __MSI_IOMMU_H */
-- 
1.9.1