iommu/amd: Convert iommu initialization to state machine

This step makes it very easy to keep track about the current
intialization state of the iommu driver. With this change we
can initialize the IOMMU hardware to a point where it can
remap interrupts and later resume the initializion to enable
dma remapping.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

drivers/iommu/amd_iommu_init.c

@@ -187,7 +187,23 @@ static u32 dev_table_size;	/* size of the device table */
 static u32 alias_table_size;	/* size of the alias table */
 static u32 rlookup_table_size;	/* size if the rlookup table */
 
+enum iommu_init_state {
+	IOMMU_START_STATE,
+	IOMMU_IVRS_DETECTED,
+	IOMMU_ACPI_FINISHED,
+	IOMMU_ENABLED,
+	IOMMU_PCI_INIT,
+	IOMMU_INTERRUPTS_EN,
+	IOMMU_DMA_OPS,
+	IOMMU_INITIALIZED,
+	IOMMU_NOT_FOUND,
+	IOMMU_INIT_ERROR,
+};
+
+static enum iommu_init_state init_state = IOMMU_START_STATE;
+
 static int amd_iommu_enable_interrupts(void);
+static int __init iommu_go_to_state(enum iommu_init_state state);
 
 static inline void update_last_devid(u16 devid)
 {
@@ -1104,7 +1120,7 @@ static void print_iommu_info(void)
 	}
 }
 
-static int amd_iommu_init_pci(void)
+static int __init amd_iommu_init_pci(void)
 {
 	struct amd_iommu *iommu;
 	int ret = 0;
@@ -1516,11 +1532,6 @@ static int __init early_amd_iommu_init(void)
 	if (!amd_iommu_detected)
 		return -ENODEV;
 
-	if (amd_iommu_dev_table != NULL) {
-		/* Hardware already initialized */
-		return 0;
-	}
-
 	status = acpi_get_table_with_size("IVRS", 0, &ivrs_base, &ivrs_size);
 	if (status == AE_NOT_FOUND)
 		return -ENODEV;
@@ -1535,7 +1546,8 @@ static int __init early_amd_iommu_init(void)
 	 * we need to handle. Upon this information the shared data
 	 * structures for the IOMMUs in the system will be allocated
 	 */
-	if (find_last_devid_acpi(ivrs_base))
+	ret = find_last_devid_acpi(ivrs_base);
+	if (ret)
 		goto out;
 
 	dev_table_size     = tbl_size(DEV_TABLE_ENTRY_SIZE);
@@ -1556,20 +1568,20 @@ static int __init early_amd_iommu_init(void)
 	amd_iommu_alias_table = (void *)__get_free_pages(GFP_KERNEL,
 			get_order(alias_table_size));
 	if (amd_iommu_alias_table == NULL)
-		goto free;
+		goto out;
 
 	/* IOMMU rlookup table - find the IOMMU for a specific device */
 	amd_iommu_rlookup_table = (void *)__get_free_pages(
 			GFP_KERNEL | __GFP_ZERO,
 			get_order(rlookup_table_size));
 	if (amd_iommu_rlookup_table == NULL)
-		goto free;
+		goto out;
 
 	amd_iommu_pd_alloc_bitmap = (void *)__get_free_pages(
 					    GFP_KERNEL | __GFP_ZERO,
 					    get_order(MAX_DOMAIN_ID/8));
 	if (amd_iommu_pd_alloc_bitmap == NULL)
-		goto free;
+		goto out;
 
 	/* init the device table */
 	init_device_table();
@@ -1594,41 +1606,17 @@ static int __init early_amd_iommu_init(void)
 	 */
 	ret = init_iommu_all(ivrs_base);
 	if (ret)
-		goto free;
+		goto out;
 
 	ret = init_memory_definitions(ivrs_base);
 	if (ret)
-		goto free;
+		goto out;
 
 out:
 	/* Don't leak any ACPI memory */
 	early_acpi_os_unmap_memory((char __iomem *)ivrs_base, ivrs_size);
 	ivrs_base = NULL;
 
-	return ret;
-
-free:
-	free_on_init_error();
-
-	goto out;
-}
-
-int __init amd_iommu_init_hardware(void)
-{
-	int ret = 0;
-
-	ret = early_amd_iommu_init();
-	if (ret)
-		return ret;
-
-	ret = amd_iommu_init_pci();
-	if (ret)
-		return ret;
-
-	enable_iommus();
-
-	register_syscore_ops(&amd_iommu_syscore_ops);
-
 	return ret;
 }
 
@@ -1686,44 +1674,99 @@ static int amd_iommu_init_dma(void)
 	return 0;
 }
 
-/*
- * This is the core init function for AMD IOMMU hardware in the system.
- * This function is called from the generic x86 DMA layer initialization
- * code.
+/****************************************************************************
  *
- * The function calls amd_iommu_init_hardware() to setup and enable the
- * IOMMU hardware if this has not happened yet. After that the driver
- * registers for the DMA-API and for the IOMMU-API as necessary.
- */
-static int __init amd_iommu_init(void)
+ * AMD IOMMU Initialization State Machine
+ *
+ ****************************************************************************/
+
+static int __init state_next(void)
 {
 	int ret = 0;
 
-	ret = amd_iommu_init_hardware();
-	if (ret)
-		goto out;
-
-	ret = amd_iommu_enable_interrupts();
-	if (ret)
-		goto free;
+	switch (init_state) {
+	case IOMMU_START_STATE:
+		if (!detect_ivrs()) {
+			init_state	= IOMMU_NOT_FOUND;
+			ret		= -ENODEV;
+		} else {
+			init_state	= IOMMU_IVRS_DETECTED;
+		}
+		break;
+	case IOMMU_IVRS_DETECTED:
+		ret = early_amd_iommu_init();
+		init_state = ret ? IOMMU_INIT_ERROR : IOMMU_ACPI_FINISHED;
+		break;
+	case IOMMU_ACPI_FINISHED:
+		early_enable_iommus();
+		register_syscore_ops(&amd_iommu_syscore_ops);
+		x86_platform.iommu_shutdown = disable_iommus;
+		init_state = IOMMU_ENABLED;
+		break;
+	case IOMMU_ENABLED:
+		ret = amd_iommu_init_pci();
+		init_state = ret ? IOMMU_INIT_ERROR : IOMMU_PCI_INIT;
+		enable_iommus_v2();
+		break;
+	case IOMMU_PCI_INIT:
+		ret = amd_iommu_enable_interrupts();
+		init_state = ret ? IOMMU_INIT_ERROR : IOMMU_INTERRUPTS_EN;
+		break;
+	case IOMMU_INTERRUPTS_EN:
+		ret = amd_iommu_init_dma();
+		init_state = ret ? IOMMU_INIT_ERROR : IOMMU_DMA_OPS;
+		break;
+	case IOMMU_DMA_OPS:
+		init_state = IOMMU_INITIALIZED;
+		break;
+	case IOMMU_INITIALIZED:
+		/* Nothing to do */
+		break;
+	case IOMMU_NOT_FOUND:
+	case IOMMU_INIT_ERROR:
+		/* Error states => do nothing */
+		ret = -EINVAL;
+		break;
+	default:
+		/* Unknown state */
+		BUG();
+	}
 
-	ret = amd_iommu_init_dma();
-	if (ret)
-		goto free;
+	return ret;
+}
 
-	amd_iommu_init_api();
+static int __init iommu_go_to_state(enum iommu_init_state state)
+{
+	int ret = 0;
 
-	x86_platform.iommu_shutdown = disable_iommus;
+	while (init_state != state) {
+		ret = state_next();
+		if (init_state == IOMMU_NOT_FOUND ||
+		    init_state == IOMMU_INIT_ERROR)
+			break;
+	}
 
-out:
 	return ret;
+}
 
-free:
-	disable_iommus();
 
-	free_on_init_error();
 
-	goto out;
+/*
+ * This is the core init function for AMD IOMMU hardware in the system.
+ * This function is called from the generic x86 DMA layer initialization
+ * code.
+ */
+static int __init amd_iommu_init(void)
+{
+	int ret;
+
+	ret = iommu_go_to_state(IOMMU_INITIALIZED);
+	if (ret) {
+		disable_iommus();
+		free_on_init_error();
+	}
+
+	return ret;
 }
 
 /****************************************************************************
@@ -1735,6 +1778,7 @@ static int __init amd_iommu_init(void)
  ****************************************************************************/
 int __init amd_iommu_detect(void)
 {
+	int ret;
 
 	if (no_iommu || (iommu_detected && !gart_iommu_aperture))
 		return -ENODEV;
@@ -1742,8 +1786,9 @@ int __init amd_iommu_detect(void)
 	if (amd_iommu_disabled)
 		return -ENODEV;
 
-	if (!detect_ivrs())
-		return -ENODEV;
+	ret = iommu_go_to_state(IOMMU_IVRS_DETECTED);
+	if (ret)
+		return ret;
 
 	amd_iommu_detected = true;
 	iommu_detected = 1;