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author | Graeme Gregory <graeme.gregory@linaro.org> | 2013-12-12 16:14:06 +0000 |
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committer | Graeme Gregory <graeme.gregory@linaro.org> | 2014-06-03 09:24:41 +0100 |
commit | 9ed4012cc9784bbe27cfa23d445449d1b0fbb550 (patch) | |
tree | 4541cc869110de1f6898a6f2ece6b60c5cd42a2c | |
parent | 337a30ff28ac7a3e9c9b11785e65479daa3b5d4f (diff) | |
download | leg-kernel-9ed4012cc9784bbe27cfa23d445449d1b0fbb550.tar.gz |
acpi: add utility acpi_keyvalue to retrieve from _DSM
Adapt code written for AMBA acpi driver to generic case for fetching
key/value pairs from _DSM method.
Signed-off-by: Brandon Anderson <brandon.anderson@amd.com>
Signed-off-by: Graeme Gregory <graeme.gregory@linaro.org>
Acked-by: Tomasz Nowicki <tomasz.nowicki@linaro.org>
-rw-r--r-- | drivers/acpi/Makefile | 1 | ||||
-rw-r--r-- | drivers/acpi/acpi_keyvalue.c | 115 | ||||
-rw-r--r-- | include/linux/acpi.h | 8 |
3 files changed, 124 insertions, 0 deletions
diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile index 3433c9e9ca75..8f584067d0ad 100644 --- a/drivers/acpi/Makefile +++ b/drivers/acpi/Makefile @@ -15,6 +15,7 @@ obj-$(CONFIG_X86) += blacklist.o # ACPI Core Subsystem (Interpreter) # obj-y += acpi.o \ + acpi_keyvalue.o \ acpica/ # All the builtin files are in the "acpi." module_param namespace. diff --git a/drivers/acpi/acpi_keyvalue.c b/drivers/acpi/acpi_keyvalue.c new file mode 100644 index 000000000000..5c3cde921b22 --- /dev/null +++ b/drivers/acpi/acpi_keyvalue.c @@ -0,0 +1,115 @@ +/* + * Key/Value handler from _DSM method + * + * Copyright (C) 2013 Linaro Ltd + * + * Author: Graeme Gregory <graeme.gregory@linaro.org> + * + * Original based on code :- + * + * Copyright (C) 2013 Advanced Micro Devices, Inc. + * + * Author: Brandon Anderson <brandon.anderson@amd.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/acpi.h> + +/* UUID: a706b112-bf0b-48d2-9fa3-95591a3c4c06 (randomly generated) */ +static const char acpi_amba_dsm_uuid[] = { + 0xa7, 0x06, 0xb1, 0x12, 0xbf, 0x0b, 0x48, 0xd2, + 0x9f, 0xa3, 0x95, 0x59, 0x1a, 0x3c, 0x4c, 0x06 +}; + +/* acpi_dsm_lookup_value() + * + * Helper to parse through ACPI _DSM object for a device. Each entry + * has three fields. + */ +int acpi_dsm_lookup_value(acpi_handle handle, + const char *tag, int index, + struct acpi_dsm_entry *entry) +{ + acpi_status status; + struct acpi_object_list input; + struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL }; + union acpi_object params[4]; + union acpi_object *obj; + int len, match_count, i; + + /* invalidate output in case there's no entry to supply */ + entry->key = NULL; + entry->value = NULL; + + if (!acpi_has_method(handle, "_DSM")) + return -ENOENT; + + input.count = 4; + params[0].type = ACPI_TYPE_BUFFER; /* UUID */ + params[0].buffer.length = sizeof(acpi_amba_dsm_uuid); + params[0].buffer.pointer = (char *)acpi_amba_dsm_uuid; + params[1].type = ACPI_TYPE_INTEGER; /* Revision */ + params[1].integer.value = 1; + params[2].type = ACPI_TYPE_INTEGER; /* Function # */ + params[2].integer.value = 1; + params[3].type = ACPI_TYPE_PACKAGE; /* Arguments */ + params[3].package.count = 0; + params[3].package.elements = NULL; + input.pointer = params; + + status = acpi_evaluate_object_typed(handle, "_DSM", + &input, &output, ACPI_TYPE_PACKAGE); + if (ACPI_FAILURE(status)) { + pr_err("failed to get _DSM package for this device\n"); + return -ENOENT; + } + + obj = (union acpi_object *)output.pointer; + + /* parse 2 objects per entry */ + match_count = 0; + for (i = 0; (i + 2) <= obj->package.count; i += 2) { + /* key must be a string */ + len = obj->package.elements[i].string.length; + if (len <= 0) + continue; + + /* check to see if this is the entry to return */ + if (strncmp(tag, obj->package.elements[i].string.pointer, + len) != 0 || + match_count < index) { + match_count++; + continue; + } + + /* copy the key */ + entry->key = kmalloc(len + 1, GFP_KERNEL); + strncpy(entry->key, + obj->package.elements[i].string.pointer, + len); + entry->key[len] = '\0'; + + /* value is a string with space-delimited fields if necessary */ + len = obj->package.elements[i + 1].string.length; + if (len > 0) { + entry->value = kmalloc(len + 1, GFP_KERNEL); + strncpy(entry->value, + obj->package.elements[i+1].string.pointer, + len); + entry->value[len] = '\0'; + } + + break; + } + + kfree(output.pointer); + + if (entry->key == NULL) + return -ENOENT; + + return 0; +} +EXPORT_SYMBOL_GPL(acpi_dsm_lookup_value); diff --git a/include/linux/acpi.h b/include/linux/acpi.h index 651abc4cde29..ca3290d22b78 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -446,6 +446,14 @@ static inline bool acpi_driver_match_device(struct device *dev, int acpi_device_uevent_modalias(struct device *, struct kobj_uevent_env *); int acpi_device_modalias(struct device *, char *, int); +struct acpi_dsm_entry { + char *key; + char *value; +}; + +int acpi_dsm_lookup_value(acpi_handle handle, + const char *tag, int index, + struct acpi_dsm_entry *entry); #define ACPI_PTR(_ptr) (_ptr) |