[RFC,v5,04/17] dma-reserved-iommu: alloc/free_reserved_iova_domain

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index a1e75cb..0775143 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -55,6 +55,12 @@  config IOMMU_DMA
 	select IOMMU_API
 	select IOMMU_IOVA
 
+# IOMMU reserved IOVA mapping (MSI doorbell)
+config IOMMU_DMA_RESERVED
+	bool
+	select IOMMU_API
+	select IOMMU_IOVA
+
 config FSL_PAMU
 	bool "Freescale IOMMU support"
 	depends on PPC32
@@ -288,6 +294,7 @@  config SPAPR_TCE_IOMMU
 config ARM_SMMU
 	bool "ARM Ltd. System MMU (SMMU) Support"
 	depends on (ARM64 || ARM) && MMU
+	select IOMMU_DMA_RESERVED
 	select IOMMU_API
 	select IOMMU_IO_PGTABLE_LPAE
 	select ARM_DMA_USE_IOMMU if ARM
@@ -301,6 +308,7 @@  config ARM_SMMU
 config ARM_SMMU_V3
 	bool "ARM Ltd. System MMU Version 3 (SMMUv3) Support"
 	depends on ARM64 && PCI
+	select IOMMU_DMA_RESERVED
 	select IOMMU_API
 	select IOMMU_IO_PGTABLE_LPAE
 	select GENERIC_MSI_IRQ_DOMAIN
diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index 42fc0c2..ea68d23 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-$(CONFIG_IOMMU_DMA_RESERVED) += dma-reserved-iommu.o
 obj-$(CONFIG_IOMMU_IO_PGTABLE) += io-pgtable.o
 obj-$(CONFIG_IOMMU_IO_PGTABLE_LPAE) += io-pgtable-arm.o
 obj-$(CONFIG_IOMMU_IOVA) += iova.o
diff --git a/drivers/iommu/dma-reserved-iommu.c b/drivers/iommu/dma-reserved-iommu.c
new file mode 100644
index 0000000..41a1add
--- /dev/null
+++ b/drivers/iommu/dma-reserved-iommu.c
@@ -0,0 +1,74 @@ 
+/*
+ * Reserved IOVA Management
+ *
+ * Copyright (c) 2015 Linaro Ltd.
+ *              www.linaro.org
+ *
+ * Copyright (C) 2000-2004 Russell King
+ *
+ * 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/iova.h>
+
+int iommu_alloc_reserved_iova_domain(struct iommu_domain *domain,
+				     dma_addr_t iova, size_t size,
+				     unsigned long order)
+{
+	unsigned long granule, mask;
+	struct iova_domain *iovad;
+	int ret = 0;
+
+	granule = 1UL << order;
+	mask = granule - 1;
+	if (iova & mask || (!size) || (size & mask))
+		return -EINVAL;
+
+	mutex_lock(&domain->reserved_mutex);
+
+	if (domain->reserved_iova_cookie) {
+		ret = -EEXIST;
+		goto unlock;
+	}
+
+	iovad = kzalloc(sizeof(struct iova_domain), GFP_KERNEL);
+	if (!iovad) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+
+	init_iova_domain(iovad, granule,
+			 iova >> order, (iova + size - 1) >> order);
+	domain->reserved_iova_cookie = iovad;
+
+unlock:
+	mutex_unlock(&domain->reserved_mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iommu_alloc_reserved_iova_domain);
+
+void iommu_free_reserved_iova_domain(struct iommu_domain *domain)
+{
+	struct iova_domain *iovad =
+		(struct iova_domain *)domain->reserved_iova_cookie;
+
+	if (!iovad)
+		return;
+
+	mutex_lock(&domain->reserved_mutex);
+
+	put_iova_domain(iovad);
+	kfree(iovad);
+
+	mutex_unlock(&domain->reserved_mutex);
+}
+EXPORT_SYMBOL_GPL(iommu_free_reserved_iova_domain);
diff --git a/include/linux/dma-reserved-iommu.h b/include/linux/dma-reserved-iommu.h
new file mode 100644
index 0000000..5bf863b
--- /dev/null
+++ b/include/linux/dma-reserved-iommu.h
@@ -0,0 +1,45 @@ 
+/*
+ * 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 __DMA_RESERVED_IOMMU_H
+#define __DMA_RESERVED_IOMMU_H
+
+#ifdef __KERNEL__
+#include <asm/errno.h>
+
+#ifdef CONFIG_IOMMU_DMA_RESERVED
+#include <linux/iommu.h>
+
+/**
+ * iommu_alloc_reserved_iova_domain: allocate the reserved iova domain
+ *
+ * @domain: iommu domain handle
+ * @iova: base iova address
+ * @size: iova window size
+ * @order: page order
+ */
+int iommu_alloc_reserved_iova_domain(struct iommu_domain *domain,
+				     dma_addr_t iova, size_t size,
+				     unsigned long order);
+
+/**
+ * iommu_free_reserved_iova_domain: free the reserved iova domain
+ *
+ * @domain: iommu domain handle
+ */
+void iommu_free_reserved_iova_domain(struct iommu_domain *domain);
+
+#endif	/* CONFIG_IOMMU_DMA_RESERVED */
+#endif	/* __KERNEL__ */
+#endif	/* __DMA_RESERVED_IOMMU_H */