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 --- drivers/acpi/Makefile | 1 + drivers/acpi/acpi_keyvalue.c | 115 +++++++++++++++++++++++++++++++++++++++++++ include/linux/acpi.h | 9 ++++ 3 files changed, 125 insertions(+) create mode 100644 drivers/acpi/acpi_keyvalue.c
diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile index 262f0be..171c15f 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 0000000..5c3cde9 --- /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 6324f8b..dad1530 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -402,6 +402,15 @@ static inline bool acpi_driver_match_device(struct device *dev, return !!acpi_match_device(drv->acpi_match_table, dev); }
+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)
#else /* !CONFIG_ACPI */