iommu/fsl: Allocate a default DMA window for a device once it's detached

from a domain.

This allows the device to be assigned back to the host, once a guest
VM exits.

Signed-off-by: Varun Sethi <Varun.Sethi@freescale.com>
Change-Id: I211b4452d2f7fce572ed8828a1fc5457d7f3b0e5
Reviewed-on: http://git.am.freescale.net:8181/5869
Tested-by: Review Code-CDREVIEW <CDREVIEW@freescale.com>
Reviewed-by: Bhushan Bharat-R65777 <Bharat.Bhushan@freescale.com>
Reviewed-by: Rivera Jose-B46482 <German.Rivera@freescale.com>

3 files changed, 81 insertions, 21 deletions

diff --git a/drivers/iommu/fsl_pamu.c b/drivers/iommu/fsl_pamu.c
index 84a5de7..42b903f 100644
--- a/drivers/iommu/fsl_pamu.c
+++ b/drivers/iommu/fsl_pamu.c
@@ -250,6 +250,40 @@ static unsigned long pamu_get_fspi_and_allocate(u32 subwin_cnt)
 	return (spaace_addr - (unsigned long)spaact) / (sizeof(struct paace));
 }
 
+/*
+ * Defaul PPAACE settings for an LIODN.
+ */
+static void setup_default_ppaace(struct paace *ppaace)
+{
+	pamu_init_ppaace(ppaace);
+	/* window size is 2^(WSE+1) bytes */
+	set_bf(ppaace->addr_bitfields, PPAACE_AF_WSE, 35);
+	ppaace->wbah = 0;
+	set_bf(ppaace->addr_bitfields, PPAACE_AF_WBAL, 0);
+	set_bf(ppaace->impl_attr, PAACE_IA_ATM,
+		PAACE_ATM_NO_XLATE);
+	set_bf(ppaace->addr_bitfields, PAACE_AF_AP,
+		PAACE_AP_PERMS_ALL);
+}
+
+/* Reset the PAACE entry to the default state */
+void enable_default_dma_window(int liodn)
+{
+	struct paace *ppaace;
+
+	ppaace = pamu_get_ppaace(liodn);
+	if (!ppaace) {
+		pr_debug("Invalid liodn entry\n");
+		return;
+	}
+
+	memset(ppaace, 0, sizeof(struct paace));
+
+	setup_default_ppaace(ppaace);
+	mb();
+	pamu_enable_liodn(liodn);
+}
+
 /* Release the subwindows reserved for a particular LIODN */
 void pamu_free_subwins(int liodn)
 {
@@ -854,15 +888,7 @@ static void __init enable_remaining_liodns(void)
 	for (liodn = 0; liodn < PAACE_NUMBER_ENTRIES; liodn++) {
 		ppaace = pamu_get_ppaace(liodn);
 		if (!get_bf(ppaace->addr_bitfields, PAACE_AF_V)) {
-			pamu_init_ppaace(ppaace);
-			/* window size is 2^(WSE+1) bytes */
-			set_bf(ppaace->addr_bitfields, PPAACE_AF_WSE, 35);
-			ppaace->wbah = 0;
-			set_bf(ppaace->addr_bitfields, PPAACE_AF_WBAL, 0);
-			set_bf(ppaace->impl_attr, PAACE_IA_ATM,
-				PAACE_ATM_NO_XLATE);
-			set_bf(ppaace->addr_bitfields, PAACE_AF_AP,
-				PAACE_AP_PERMS_ALL);
+			setup_default_ppaace(ppaace);
 			mb();
 			pamu_enable_liodn(liodn);
 		}
@@ -888,15 +914,7 @@ static void __init setup_liodns(void)
 				continue;
 			}
 			ppaace = pamu_get_ppaace(liodn);
-			pamu_init_ppaace(ppaace);
-			/* window size is 2^(WSE+1) bytes */
-			set_bf(ppaace->addr_bitfields, PPAACE_AF_WSE, 35);
-			ppaace->wbah = 0;
-			set_bf(ppaace->addr_bitfields, PPAACE_AF_WBAL, 0);
-			set_bf(ppaace->impl_attr, PAACE_IA_ATM,
-				PAACE_ATM_NO_XLATE);
-			set_bf(ppaace->addr_bitfields, PAACE_AF_AP,
-				PAACE_AP_PERMS_ALL);
+			setup_default_ppaace(ppaace);
 			if (of_device_is_compatible(node, "fsl,qman-portal"))
 				setup_dpaa_paace(ppaace, QMAN_PORTAL_PAACE);
 			if (of_device_is_compatible(node, "fsl,qman"))
diff --git a/drivers/iommu/fsl_pamu.h b/drivers/iommu/fsl_pamu.h
index fd9dd6d..119ae04 100644
--- a/drivers/iommu/fsl_pamu.h
+++ b/drivers/iommu/fsl_pamu.h
@@ -407,5 +407,6 @@ void get_ome_index(u32 *omi_index, struct device *dev);
 int  pamu_update_paace_field(int liodn, u32 subwin, int field, u32 value);
 int pamu_disable_spaace(int liodn, u32 subwin);
 u32 pamu_get_max_subwin_cnt(void);
+void enable_default_dma_window(int liodn);
 
 #endif  /* __FSL_PAMU_H */
diff --git a/drivers/iommu/fsl_pamu_domain.c b/drivers/iommu/fsl_pamu_domain.c
index c18b76f..c9eb0f9 100644
--- a/drivers/iommu/fsl_pamu_domain.c
+++ b/drivers/iommu/fsl_pamu_domain.c
@@ -338,15 +338,56 @@ static inline struct device_domain_info *find_domain(struct device *dev)
 	return dev->archdata.iommu_domain;
 }
 
+/* Disable device DMA capability and enable default DMA window */
+static void disable_device_dma(struct device_domain_info *info,
+				int enable_dma_window)
+{
+#ifdef CONFIG_PCI
+	if (info->dev->bus == &pci_bus_type) {
+		struct pci_dev *pdev = NULL;
+		pdev = to_pci_dev(info->dev);
+		if (pci_is_enabled(pdev))
+			pci_disable_device(pdev);
+	}
+#endif
+
+	if (enable_dma_window)
+		enable_default_dma_window(info->liodn);
+}
+
+static int check_for_shared_liodn(struct device_domain_info *info)
+{
+	struct device_domain_info *tmp;
+
+	/*
+	 * Sanity check, to ensure that this is not a
+	 * shared LIODN. In case of a PCIe controller
+	 * it's possible that all PCIe devices share
+	 * the same LIODN.
+	 */
+	list_for_each_entry(tmp, &info->domain->devices, link) {
+		if (info->liodn == tmp->liodn)
+			return 1;
+	}
+
+	return 0;
+}
+
 static void remove_device_ref(struct device_domain_info *info, u32 win_cnt)
 {
+	int enable_dma_window = 0;
+
 	list_del(&info->link);
 	spin_lock(&iommu_lock);
-	if (win_cnt > 1)
-		pamu_free_subwins(info->liodn);
-	pamu_disable_liodn(info->liodn);
+	if (!check_for_shared_liodn(info)) {
+		if (win_cnt > 1)
+			pamu_free_subwins(info->liodn);
+		pamu_disable_liodn(info->liodn);
+		enable_dma_window = 1;
+	}
 	spin_unlock(&iommu_lock);
 	spin_lock(&device_domain_lock);
+	disable_device_dma(info, enable_dma_window);
 	info->dev->archdata.iommu_domain = NULL;
 	kmem_cache_free(iommu_devinfo_cache, info);
 	spin_unlock(&device_domain_lock);