[PATCH -stable] ibft: Fix finding IBFT ACPI table on UEFI

commit 935a9fee51c945b8942be2d7b4bae069167b4886 upstream.

it is backporting for:
	kernel 2.6.36, 2.6.37, 2.6.38, 2.6.39

Found one system with UEFI/iBFT, kernel does not detect the iBFT during
iscsi_ibft module loading.

Root cause: on x86 (UEFI), we are calling of find_ibft_region() much earlier
	- specifically in setup_arch() before ACPI is enabled.

Try to split acpi checking code out and call that later

At that time ACPI iBFT already get permanent mapped with ioremap.
So isa_virt_to_bus() will get wrong phys from right virt address.
We could just skip that phys address printing.

For legacy one, print the found address early.

-v2: update comments and description according to Konrad.
-v3: fix problem about module use case that is found by Konrad.
-v4: use acpi_get_table() instead of acpi_table_parse() to handle module use case that is found by Konrad again..

Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
 drivers/firmware/iscsi_ibft.c      |   42 +++++++++++++++++++++++++++++++++++--
 drivers/firmware/iscsi_ibft_find.c |   22 +------------------
 2 files changed, 42 insertions(+), 22 deletions(-)

Index: linux-2.6/drivers/firmware/iscsi_ibft.c
===================================================================
--- linux-2.6.orig/drivers/firmware/iscsi_ibft.c
+++ linux-2.6/drivers/firmware/iscsi_ibft.c
@@ -738,6 +738,37 @@ static void __exit ibft_exit(void)
 	ibft_cleanup();
 }
 
+#ifdef CONFIG_ACPI
+static const struct {
+	char *sign;
+} ibft_signs[] = {
+	/*
+	 * One spec says "IBFT", the other says "iBFT". We have to check
+	 * for both.
+	 */
+	{ ACPI_SIG_IBFT },
+	{ "iBFT" },
+};
+
+static void __init acpi_find_ibft_region(void)
+{
+	int i;
+	struct acpi_table_header *table = NULL;
+
+	if (acpi_disabled)
+		return;
+
+	for (i = 0; i < ARRAY_SIZE(ibft_signs) && !ibft_addr; i++) {
+		acpi_get_table(ibft_signs[i].sign, 0, &table);
+		ibft_addr = (struct acpi_table_ibft *)table;
+	}
+}
+#else
+static void __init acpi_find_ibft_region(void)
+{
+}
+#endif
+
 /*
  * ibft_init() - creates sysfs tree entries for the iBFT data.
  */
@@ -745,9 +776,16 @@ static int __init ibft_init(void)
 {
 	int rc = 0;
 
+	/*
+	   As on UEFI systems the setup_arch()/find_ibft_region()
+	   is called before ACPI tables are parsed and it only does
+	   legacy finding.
+	*/
+	if (!ibft_addr)
+		acpi_find_ibft_region();
+
 	if (ibft_addr) {
-		printk(KERN_INFO "iBFT detected at 0x%llx.\n",
-		       (u64)isa_virt_to_bus(ibft_addr));
+		pr_info("iBFT detected.\n");
 
 		rc = ibft_check_device();
 		if (rc)
Index: linux-2.6/drivers/firmware/iscsi_ibft_find.c
===================================================================
--- linux-2.6.orig/drivers/firmware/iscsi_ibft_find.c
+++ linux-2.6/drivers/firmware/iscsi_ibft_find.c
@@ -49,14 +49,6 @@ EXPORT_SYMBOL_GPL(ibft_addr);
 #define VGA_MEM 0xA0000 /* VGA buffer */
 #define VGA_SIZE 0x20000 /* 128kB */
 
-#ifdef CONFIG_ACPI
-static int __init acpi_find_ibft(struct acpi_table_header *header)
-{
-	ibft_addr = (struct acpi_table_ibft *)header;
-	return 0;
-}
-#endif /* CONFIG_ACPI */
-
 static int __init find_ibft_in_mem(void)
 {
 	unsigned long pos;
@@ -77,6 +69,7 @@ static int __init find_ibft_in_mem(void)
 			 * the table cannot be valid. */
 			if (pos + len <= (IBFT_END-1)) {
 				ibft_addr = (struct acpi_table_ibft *)virt;
+				pr_info("iBFT found at 0x%lx.\n", pos);
 				break;
 			}
 		}
@@ -92,21 +85,10 @@ unsigned long __init find_ibft_region(un
 
 	ibft_addr = NULL;
 
-#ifdef CONFIG_ACPI
-	/*
-	 * One spec says "IBFT", the other says "iBFT". We have to check
-	 * for both.
-	 */
-	if (!ibft_addr)
-		acpi_table_parse(ACPI_SIG_IBFT, acpi_find_ibft);
-	if (!ibft_addr)
-		acpi_table_parse(IBFT_SIGN, acpi_find_ibft);
-#endif /* CONFIG_ACPI */
-
 	/* iBFT 1.03 section 1.4.3.1 mandates that UEFI machines will
 	 * only use ACPI for this */
 
-	if (!ibft_addr && !efi_enabled)
+	if (!efi_enabled)
 		find_ibft_in_mem();
 
 	if (ibft_addr) {