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Subject[PATCH v6 1/2] ACPI: utils: Add api to read _SUB from ACPI
Date
Add a wrapper function to read the _SUB string from ACPI.

Signed-off-by: Stefan Binding <sbinding@opensource.cirrus.com>
---
drivers/acpi/utils.c | 38 ++++++++++++++++++++++++++++++++++++++
include/linux/acpi.h | 6 ++++++
2 files changed, 44 insertions(+)

diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c
index 3a9773a09e19..5a7b8065e77f 100644
--- a/drivers/acpi/utils.c
+++ b/drivers/acpi/utils.c
@@ -291,6 +291,44 @@ int acpi_get_local_address(acpi_handle handle, u32 *addr)
}
EXPORT_SYMBOL(acpi_get_local_address);

+#define ACPI_MAX_SUB_BUF_SIZE 9
+
+const char *acpi_get_subsystem_id(acpi_handle handle)
+{
+ struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+ union acpi_object *obj;
+ acpi_status status;
+ const char *sub;
+ size_t len;
+
+ status = acpi_evaluate_object(handle, METHOD_NAME__SUB, NULL, &buffer);
+ if (ACPI_FAILURE(status)) {
+ acpi_handle_debug(handle, "Reading ACPI _SUB failed: %#x\n", status);
+ return ERR_PTR(-ENODATA);
+ }
+
+ obj = buffer.pointer;
+ if (obj->type == ACPI_TYPE_STRING) {
+ len = strlen(obj->string.pointer);
+ if (len < ACPI_MAX_SUB_BUF_SIZE && len > 0) {
+ sub = kstrdup(obj->string.pointer, GFP_KERNEL);
+ if (!sub)
+ sub = ERR_PTR(-ENOMEM);
+ } else {
+ acpi_handle_err(handle, "ACPI _SUB Length %zu is Invalid\n", len);
+ sub = ERR_PTR(-ENODATA);
+ }
+ } else {
+ acpi_handle_warn(handle, "Warning ACPI _SUB did not return a string\n");
+ sub = ERR_PTR(-ENODATA);
+ }
+
+ acpi_os_free(buffer.pointer);
+
+ return sub;
+}
+EXPORT_SYMBOL_GPL(acpi_get_subsystem_id);
+
acpi_status
acpi_evaluate_reference(acpi_handle handle,
acpi_string pathname,
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 2a0e95336094..447898685e09 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -762,6 +762,7 @@ static inline u64 acpi_arch_get_root_pointer(void)
#endif

int acpi_get_local_address(acpi_handle handle, u32 *addr);
+const char *acpi_get_subsystem_id(acpi_handle handle);

#else /* !CONFIG_ACPI */

@@ -1023,6 +1024,11 @@ static inline int acpi_get_local_address(acpi_handle handle, u32 *addr)
return -ENODEV;
}

+static inline const char *acpi_get_subsystem_id(acpi_handle handle)
+{
+ return ERR_PTR(-ENODEV);
+}
+
static inline int acpi_register_wakeup_handler(int wake_irq,
bool (*wakeup)(void *context), void *context)
{
--
2.25.1
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