[v4] Add address translation interface using ACPI DSM

["Luck, Tony" <tony.luck@intel.com>]

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 <qiuxu.zhuo@intel.com>]

Tested-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
---

v4: Now with *all* the bits from v2 and v3.

    Also fixes include/linux/adxl.h ... it shouldn't have the stubs
    any more. A driver that does #include <linux/adxl.h> should also
    have a "select ACPI_ADXL". It makes no sense to wait until driver
    module load time to tell the user they missed a step.

 drivers/acpi/Kconfig     |   3 +
 drivers/acpi/Makefile    |   3 +
 drivers/acpi/acpi_adxl.c | 192 +++++++++++++++++++++++++++++++++++++++
 include/linux/adxl.h     |  13 +++
 4 files changed, 211 insertions(+)
 create mode 100644 drivers/acpi/acpi_adxl.c
 create mode 100644 include/linux/adxl.h

diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index dd1eea90f67f..09991cc91b89 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -498,6 +498,9 @@ config ACPI_EXTLOG
 	  driver adds support for that functionality with corresponding
 	  tracepoint which carries that information to userspace.
 
+config ACPI_ADXL
+	bool
+
 menuconfig PMIC_OPREGION
 	bool "PMIC (Power Management Integrated Circuit) operation region support"
 	help
diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 6d59aa109a91..edc039313cd6 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -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
diff --git a/drivers/acpi/acpi_adxl.c b/drivers/acpi/acpi_adxl.c
new file mode 100644
index 000000000000..4c47fc75145c
--- /dev/null
+++ b/drivers/acpi/acpi_adxl.c
@@ -0,0 +1,192 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Address translation interface via ACPI DSM.
+ * Copyright (C) 2018 Intel Corporation
+ *
+ * Specification for this interface is available at:
+ *
+ *	https://cdrdv2.intel.com/v1/dl/getContent/603354
+ */
+
+#include <linux/acpi.h>
+#include <linux/adxl.h>
+
+#define ADXL_REVISION			0x1
+#define ADXL_IDX_GET_ADDR_PARAMS	0x1
+#define ADXL_IDX_FORWARD_TRANSLATE	0x2
+#define ACPI_ADXL_PATH			"\\_SB.ADXL"
+
+/*
+ * The specification doesn't provide a limit on how many
+ * components are in a memory address. But since we allocate
+ * memory based on the number the BIOS tells us, we should
+ * defend against insane values.
+ */
+#define ADXL_MAX_COMPONENTS		500
+
+#undef pr_fmt
+#define pr_fmt(fmt) "ADXL: " fmt
+
+static acpi_handle handle;
+static union acpi_object *params;
+static const guid_t adxl_guid =
+	GUID_INIT(0xAA3C050A, 0x7EA4, 0x4C1F,
+		  0xAF, 0xDA, 0x12, 0x67, 0xDF, 0xD3, 0xD4, 0x8D);
+
+static int adxl_count;
+static char **adxl_component_names;
+
+static union acpi_object *adxl_dsm(int cmd, union acpi_object argv[])
+{
+	union acpi_object *obj, *o;
+
+	obj = acpi_evaluate_dsm_typed(handle, &adxl_guid, ADXL_REVISION,
+				      cmd, argv, ACPI_TYPE_PACKAGE);
+	if (!obj) {
+		pr_info("DSM call failed for cmd=%d\n", cmd);
+		return NULL;
+	}
+
+	if (obj->package.count != 2) {
+		pr_info("Bad pkg count %d\n", obj->package.count);
+		goto err;
+	}
+
+	o = obj->package.elements;
+	if (o->type != ACPI_TYPE_INTEGER) {
+		pr_info("Bad 1st element type %d\n", o->type);
+		goto err;
+	}
+	if (o->integer.value) {
+		pr_info("Bad ret val %llu\n", o->integer.value);
+		goto err;
+	}
+
+	o = obj->package.elements + 1;
+	if (o->type != ACPI_TYPE_PACKAGE) {
+		pr_info("Bad 2nd element type %d\n", o->type);
+		goto err;
+	}
+	return obj;
+
+err:
+	ACPI_FREE(obj);
+	return NULL;
+}
+
+/**
+ * adxl_get_component_names - get list of memory component names
+ * Returns NULL terminated list of string names
+ *
+ * Give the caller a pointer to the list of memory component names
+ * e.g. { "SystemAddress", "ProcessorSocketId", "ChannelId", ... NULL }
+ * Caller should count how many strings in order to allocate a buffer
+ * for the return from adxl_decode().
+ */
+const char * const *adxl_get_component_names(void)
+{
+	return (const char * const *)adxl_component_names;
+}
+EXPORT_SYMBOL_GPL(adxl_get_component_names);
+
+/**
+ * adxl_decode - ask BIOS to decode a system address to memory address
+ * @addr: the address to decode
+ * @component_values: pointer to array of values for each component
+ * Returns 0 on success, negative error code otherwise
+ *
+ * The index of each value returned in the array matches the index of
+ * each component name returned by adxl_get_component_names().
+ * Components that are not defined for this address translation (e.g.
+ * mirror channel number for a non-mirrored address) are set to ~0ull.
+ */
+int adxl_decode(u64 addr, u64 component_values[])
+{
+	union acpi_object argv4[2], *results, *r;
+	int i, cnt;
+
+	if (!adxl_component_names)
+		return -EOPNOTSUPP;
+
+	argv4[0].type = ACPI_TYPE_PACKAGE;
+	argv4[0].package.count = 1;
+	argv4[0].package.elements = &argv4[1];
+	argv4[1].integer.type = ACPI_TYPE_INTEGER;
+	argv4[1].integer.value = addr;
+
+	results = adxl_dsm(ADXL_IDX_FORWARD_TRANSLATE, argv4);
+	if (!results)
+		return -EINVAL;
+
+	r = results->package.elements + 1;
+	cnt = r->package.count;
+	if (cnt != adxl_count) {
+		ACPI_FREE(results);
+		return -EINVAL;
+	}
+	r = r->package.elements;
+
+	for (i = 0; i < cnt; i++)
+		component_values[i] = r[i].integer.value;
+
+	ACPI_FREE(results);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(adxl_decode);
+
+static int __init adxl_init(void)
+{
+	char *path = ACPI_ADXL_PATH;
+	union acpi_object *p;
+	acpi_status status;
+	int i;
+
+	status = acpi_get_handle(NULL, path, &handle);
+	if (ACPI_FAILURE(status)) {
+		pr_info("No ACPI handle for path %s\n", path);
+		return -ENODEV;
+	}
+
+	if (!acpi_has_method(handle, "_DSM")) {
+		pr_info("No DSM method\n");
+		return -ENODEV;
+	}
+
+	if (!acpi_check_dsm(handle, &adxl_guid, ADXL_REVISION,
+			    ADXL_IDX_GET_ADDR_PARAMS |
+			    ADXL_IDX_FORWARD_TRANSLATE)) {
+		pr_info("DSM method does not support forward translate\n");
+		return -ENODEV;
+	}
+
+	params = adxl_dsm(ADXL_IDX_GET_ADDR_PARAMS, NULL);
+	if (!params) {
+		pr_info("Failed to get component names\n");
+		return -ENODEV;
+	}
+
+	p = params->package.elements + 1;
+	adxl_count = p->package.count;
+	if (adxl_count > ADXL_MAX_COMPONENTS) {
+		pr_info("Insane number of address component names %d\n", adxl_count);
+		ACPI_FREE(params);
+		return -ENODEV;
+	}
+	p = p->package.elements;
+
+	/*
+	 * Allocate one extra for NULL termination.
+	 */
+	adxl_component_names = kcalloc(adxl_count + 1, sizeof(char *), GFP_KERNEL);
+	if (!adxl_component_names) {
+		ACPI_FREE(params);
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < adxl_count; i++)
+		adxl_component_names[i] = p[i].string.pointer;
+
+	return 0;
+}
+subsys_initcall(adxl_init);
diff --git a/include/linux/adxl.h b/include/linux/adxl.h
new file mode 100644
index 000000000000..2a629acb4c3f
--- /dev/null
+++ b/include/linux/adxl.h
@@ -0,0 +1,13 @@
+/* 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
+
+const char * const *adxl_get_component_names(void);
+int adxl_decode(u64 addr, u64 component_values[]);
+
+#endif /* _LINUX_ADXL_H */