ACPI / adxl: Address translation interface using ACPI DSM

Some new servers provide an interface so that the OS can ask the BIOS to translate a system physical address to a memory address (socket, memory controller, channel, rank, dimm, etc.). This is useful for EDAC drivers that want to take the address of an error reported in a machine check bank and let the user know which DIMM may need to be replaced.

Specification for this interface is available at:

    https://cdrdv2.intel.com/v1/dl/getContent/603354

[Based on earlier code by Qiuxu Zhuo <[email protected]>]

---
Comments addressed since last version:
Rafael:
Added URL for specification (to commit & header comment) Fixed NULL error return from error case of adxl_dsm()

Boris:
Added sanity check on number of address components (also added check that number of values returned by
decode operation matches number of strings)
g/pr_debug/s//pr_info/
Added "." at end of sentences in comments Make return from adxl_get_component_names() immutable

 drivers/acpi/Kconfig     |  10 ++
 drivers/acpi/Makefile    |   3 +
 drivers/acpi/acpi_adxl.c | 199 +++++++++++++++++++++++++++++++++++++++
 include/linux/adxl.h     |  25 +++++
 4 files changed, 237 insertions(+)
 create mode 100644 drivers/acpi/acpi_adxl.c
 create mode 100644 include/linux/adxl.h

index dd1eea90f67f..327c93b51cb7 100644
@@ -498,6 +498,16 @@ config ACPI_EXTLOG
 	  driver adds support for that functionality with corresponding
 	  tracepoint which carries that information to userspace.
 
+config ACPI_ADXL
+	bool "Physical address to DIMM address translation"
+	def_bool n
+	help
+	  Enable interface that calls into BIOS using a DSM (device
+	  specific method) to convert system physical addresses
+	  to DIMM (socket, channel, rank, dimm, etc.).
+	  Only available on some servers.
+	  Used by newer EDAC drivers.
+
 menuconfig PMIC_OPREGION
 	bool "PMIC (Power Management Integrated Circuit) operation region support"
 	help

index 6d59aa109a91..edc039313cd6 100644
@@ -61,6 +61,9 @@ acpi-$(CONFIG_ACPI_LPIT)	+= acpi_lpit.o
 acpi-$(CONFIG_ACPI_GENERIC_GSI) += irq.o
 acpi-$(CONFIG_ACPI_WATCHDOG)	+= acpi_watchdog.o
 
+# Address translation
+acpi-$(CONFIG_ACPI_ADXL)	+= acpi_adxl.o
+
 # These are (potentially) separate modules
 
 # IPMI may be used by other drivers, so it has to initialise before them

new file mode 100644
index 000000000000..6023704e5d0b
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Address translation interface via ACPI DSM.
+ * Copyright (C) 2018 Intel Corporation
+ */
+
+#ifndef _LINUX_ADXL_H
+#define _LINUX_ADXL_H
+
+#ifdef CONFIG_ACPI_ADXL
+const char * const *adxl_get_component_names(void);
+int adxl_decode(u64 addr, u64 component_values[]);
+#else
+static inline const char * const *adxl_get_component_names(void)
+{
+	return NULL;
+}
+
+static inline int adxl_decode(u64 addr, u64 component_values[])
+{
+	return -EOPNOTSUPP;
+}
+#endif
+
+#endif /* _LINUX_ADXL_H */