[PATCH] firmware: added a firmware information passing method FFI

[Yunhui Cui]

Some BootLoaders do not support UEFI and cannot pass ACPI/SBMIOS table
addresses through UEFI, such as coreboot.

On the x86 platform, we pass the ACPI/SMBIOS table through the reserved
address segment 0xF0000, but other arches usually do not reserve this
address segment.

We have added a new firmware information transmission method named FFI
(FDT FIRMWARE INTERFACE), through FDT to obtain firmware information,
such as the base address of the ACPI and SMBIOS table.

Signed-off-by: Yunhui Cui <cuiyunhui@xxxxxxxxxxxxx>
---
 MAINTAINERS                 |  6 +++
 drivers/acpi/osl.c          |  8 ++++
 drivers/firmware/Kconfig    | 12 +++++
 drivers/firmware/Makefile   |  1 +
 drivers/firmware/dmi_scan.c | 96 ++++++++++++++++++++++---------------
 drivers/firmware/ffi.c      | 56 ++++++++++++++++++++++
 include/linux/ffi.h         | 15 ++++++
 7 files changed, 155 insertions(+), 39 deletions(-)
 create mode 100644 drivers/firmware/ffi.c
 create mode 100644 include/linux/ffi.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 8d5bc223f305..94664f3b4c96 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7750,6 +7750,12 @@ F:	arch/x86/platform/efi/
 F:	drivers/firmware/efi/
 F:	include/linux/efi*.h
 
+FDT FIRMWARE INTERFACE (FFI)
+M:	Yunhui Cui cuiyunhui@xxxxxxxxxxxxx
+S:	Maintained
+F:	drivers/firmware/ffi.c
+F:	include/linux/ffi.h
+
 EXTERNAL CONNECTOR SUBSYSTEM (EXTCON)
 M:	MyungJoo Ham <myungjoo.ham@xxxxxxxxxxx>
 M:	Chanwoo Choi <cw00.choi@xxxxxxxxxxx>
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 3269a888fb7a..d45000041d2b 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -25,6 +25,7 @@
 #include <linux/nmi.h>
 #include <linux/acpi.h>
 #include <linux/efi.h>
+#include <linux/ffi.h>
 #include <linux/ioport.h>
 #include <linux/list.h>
 #include <linux/jiffies.h>
@@ -206,6 +207,13 @@ acpi_physical_address __init acpi_os_get_root_pointer(void)
 	if (pa)
 		return pa;
 
+#ifdef CONFIG_FDT_FW_INTERFACE
+	if (fdt_fwtbl.acpi20 != FDT_INVALID_FWTBL_ADDR)
+		return fdt_fwtbl.acpi20;
+	if (fdt_fwtbl.acpi != FDT_INVALID_FWTBL_ADDR)
+		return fdt_fwtbl.acpi;
+	pr_err("Fdt system description tables not found\n");
+#endif
 	if (efi_enabled(EFI_CONFIG_TABLES)) {
 		if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
 			return efi.acpi20;
diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index b59e3041fd62..13c67b50c17a 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -303,6 +303,18 @@ config TURRIS_MOX_RWTM
 	  other manufacturing data and also utilize the Entropy Bit Generator
 	  for hardware random number generation.
 
+config FDT_FW_INTERFACE
+	bool "An interface for passing firmware info through FDT"
+	depends on OF && OF_FLATTREE
+	default n
+	help
+	  When some bootloaders do not support UEFI, and the arch does not
+	  support SMBIOS_ENTRY_POINT_SCAN_START, then you can enable this option
+	  to support the transfer of firmware information, such as acpi, smbios
+	  tables.
+
+	  Say Y here if you want to pass firmware information by FDT.
+
 source "drivers/firmware/arm_ffa/Kconfig"
 source "drivers/firmware/broadcom/Kconfig"
 source "drivers/firmware/cirrus/Kconfig"
diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
index 28fcddcd688f..3b8b5d0868a6 100644
--- a/drivers/firmware/Makefile
+++ b/drivers/firmware/Makefile
@@ -33,6 +33,7 @@ obj-y				+= cirrus/
 obj-y				+= meson/
 obj-$(CONFIG_GOOGLE_FIRMWARE)	+= google/
 obj-y				+= efi/
+obj-$(CONFIG_FDT_FW_INTERFACE)	+= ffi.o
 obj-y				+= imx/
 obj-y				+= psci/
 obj-y				+= smccc/
diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index 015c95a825d3..1e1a74ed7d3b 100644
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -6,6 +6,7 @@
 #include <linux/ctype.h>
 #include <linux/dmi.h>
 #include <linux/efi.h>
+#include <linux/ffi.h>
 #include <linux/memblock.h>
 #include <linux/random.h>
 #include <asm/dmi.h>
@@ -655,54 +656,71 @@ static int __init dmi_smbios3_present(const u8 *buf)
 	return 1;
 }
 
-static void __init dmi_scan_machine(void)
+/*
+ * According to the DMTF SMBIOS reference spec v3.0.0, it is
+ * allowed to define both the 64-bit entry point (smbios3) and
+ * the 32-bit entry point (smbios), in which case they should
+ * either both point to the same SMBIOS structure table, or the
+ * table pointed to by the 64-bit entry point should contain a
+ * superset of the table contents pointed to by the 32-bit entry
+ * point (section 5.2)
+ * This implies that the 64-bit entry point should have
+ * precedence if it is defined and supported by the OS. If we
+ * have the 64-bit entry point, but fail to decode it, fall
+ * back to the legacy one (if available)
+ */
+static int __init dmi_sacn_smbios(unsigned long smbios3, unsigned long smbios)
 {
-	char __iomem *p, *q;
+	char __iomem *p;
 	char buf[32];
+	#define INVALID_TABLE_ADDR (~0UL)
 
-	if (efi_enabled(EFI_CONFIG_TABLES)) {
-		/*
-		 * According to the DMTF SMBIOS reference spec v3.0.0, it is
-		 * allowed to define both the 64-bit entry point (smbios3) and
-		 * the 32-bit entry point (smbios), in which case they should
-		 * either both point to the same SMBIOS structure table, or the
-		 * table pointed to by the 64-bit entry point should contain a
-		 * superset of the table contents pointed to by the 32-bit entry
-		 * point (section 5.2)
-		 * This implies that the 64-bit entry point should have
-		 * precedence if it is defined and supported by the OS. If we
-		 * have the 64-bit entry point, but fail to decode it, fall
-		 * back to the legacy one (if available)
-		 */
-		if (efi.smbios3 != EFI_INVALID_TABLE_ADDR) {
-			p = dmi_early_remap(efi.smbios3, 32);
-			if (p == NULL)
-				goto error;
-			memcpy_fromio(buf, p, 32);
-			dmi_early_unmap(p, 32);
-
-			if (!dmi_smbios3_present(buf)) {
-				dmi_available = 1;
-				return;
-			}
-		}
-		if (efi.smbios == EFI_INVALID_TABLE_ADDR)
-			goto error;
-
-		/* This is called as a core_initcall() because it isn't
-		 * needed during early boot.  This also means we can
-		 * iounmap the space when we're done with it.
-		 */
-		p = dmi_early_remap(efi.smbios, 32);
+	if (smbios3 != INVALID_TABLE_ADDR) {
+		p = dmi_early_remap(smbios3, 32);
 		if (p == NULL)
-			goto error;
+			return -1;
 		memcpy_fromio(buf, p, 32);
 		dmi_early_unmap(p, 32);
 
-		if (!dmi_present(buf)) {
+		if (!dmi_smbios3_present(buf)) {
 			dmi_available = 1;
-			return;
+			return 0;
 		}
+	}
+
+	if (smbios == INVALID_TABLE_ADDR)
+		return -1;
+
+	/*
+	 * This is called as a core_initcall() because it isn't
+	 * needed during early boot.  This also means we can
+	 * iounmap the space when we're done with it.
+	 */
+	p = dmi_early_remap(smbios, 32);
+	if (p == NULL)
+		return -1;
+	memcpy_fromio(buf, p, 32);
+	dmi_early_unmap(p, 32);
+
+	if (!dmi_present(buf)) {
+		dmi_available = 1;
+		return 0;
+	}
+	return -1;
+}
+
+static void __init dmi_scan_machine(void)
+{
+	char __iomem *p, *q;
+	char buf[32];
+
+#ifdef CONFIG_FDT_FW_INTERFACE
+	if (dmi_sacn_smbios(fdt_fwtbl.smbios3, fdt_fwtbl.smbios))
+		goto error;
+#endif
+	if (efi_enabled(EFI_CONFIG_TABLES)) {
+		if (dmi_sacn_smbios(efi.smbios3, efi.smbios))
+			goto error;
 	} else if (IS_ENABLED(CONFIG_DMI_SCAN_MACHINE_NON_EFI_FALLBACK)) {
 		p = dmi_early_remap(SMBIOS_ENTRY_POINT_SCAN_START, 0x10000);
 		if (p == NULL)
diff --git a/drivers/firmware/ffi.c b/drivers/firmware/ffi.c
new file mode 100644
index 000000000000..83c7abf22220
--- /dev/null
+++ b/drivers/firmware/ffi.c
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kobject.h>
+#include <linux/ffi.h>
+#include <linux/of_fdt.h>
+#include <linux/libfdt.h>
+
+struct fdt_fwtable __read_mostly fdt_fwtbl = {
+	.acpi			= FDT_INVALID_FWTBL_ADDR,
+	.acpi20			= FDT_INVALID_FWTBL_ADDR,
+	.smbios			= FDT_INVALID_FWTBL_ADDR,
+	.smbios3		= FDT_INVALID_FWTBL_ADDR,
+};
+EXPORT_SYMBOL(fdt_fwtbl);
+
+void __init of_fdt_fwtbl(void)
+{
+	int cfgtbl, len;
+	fdt64_t *prop;
+
+	cfgtbl = fdt_path_offset(initial_boot_params, "/cfgtables");
+	if (cfgtbl < 0) {
+		pr_info("cfgtables not found.\n");
+		return;
+	}
+	prop = fdt_getprop_w(initial_boot_params, cfgtbl, "smbios_phy_ptr", &len);
+	if (!prop || len != sizeof(u64))
+		pr_info("smbios_phy_ptr not found.\n");
+	else
+		fdt_fwtbl.smbios = fdt64_to_cpu(*prop);
+
+	prop = fdt_getprop_w(initial_boot_params, cfgtbl, "smbios3_phy_ptr", &len);
+	if (!prop || len != sizeof(u64))
+		pr_info("smbios3_phy_ptr not found.\n");
+	else
+		fdt_fwtbl.smbios3 = fdt64_to_cpu(*prop);
+
+	prop = fdt_getprop_w(initial_boot_params, cfgtbl, "acpi_phy_ptr", &len);
+	if (!prop || len != sizeof(u64))
+		pr_info("acpi_phy_ptr not found.\n");
+	else
+		fdt_fwtbl.acpi = fdt64_to_cpu(*prop);
+
+	prop = fdt_getprop_w(initial_boot_params, cfgtbl, "acpi20_phy_ptr", &len);
+	if (!prop || len != sizeof(u64))
+		pr_info("acpi20_phy_ptr not found.\n");
+	else
+		fdt_fwtbl.acpi20 = fdt64_to_cpu(*prop);
+}
+
+void __init fdt_fwtbl_init(void)
+{
+	of_fdt_fwtbl();
+}
diff --git a/include/linux/ffi.h b/include/linux/ffi.h
new file mode 100644
index 000000000000..ffb50810a01e
--- /dev/null
+++ b/include/linux/ffi.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _LINUX_FDT_FW_H
+#define _LINUX_FDT_FW_H
+
+#define FDT_INVALID_FWTBL_ADDR		(~0UL)
+extern struct fdt_fwtable {
+	unsigned long			acpi;
+	unsigned long			acpi20;
+	unsigned long			smbios;
+	unsigned long			smbios3;
+	unsigned long			flags;
+} fdt_fwtbl;
+
+#endif
-- 
2.20.1