[PATCH v4 2/5] acpi: Store CRC-32 hash of the _PLD in struct acpi_device

Heikki Krogerus
2021-12-22T14:33:02Z

Storing CRC-32 hash of the Physical Location of Device
object (_PLD) with devices that have it. The hash is stored
to a new struct acpi_device member "pld_crc".

The hash makes it easier to find devices that share a
location, as there is no need to evaluate the entire object
every time. Knowledge about devices that share a location
can be used in device drivers that need to know the
connections to other components inside a system. USB3 ports
will for example always share their location with a USB2
port.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
---
drivers/acpi/scan.c | 16 ++++++++++++++++
include/acpi/acpi_bus.h | 14 +++++++++++++-
2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 7ff55a197a583..113414c46b713 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -19,6 +19,7 @@
#include <linux/dma-map-ops.h>
#include <linux/platform_data/x86/apple.h>
#include <linux/pgtable.h>
+#include <linux/crc32.h>

#include "internal.h"

@@ -667,6 +668,19 @@ static int acpi_tie_acpi_dev(struct acpi_device *adev)
return 0;
}

+static void acpi_store_pld_crc(struct acpi_device *adev)
+{
+ struct acpi_pld_info *pld;
+ acpi_status status;
+
+ status = acpi_get_physical_device_location(adev->handle, &pld);
+ if (ACPI_FAILURE(status))
+ return;
+
+ adev->pld_crc = crc32(~0, pld, sizeof(*pld));
+ ACPI_FREE(pld);
+}
+
static int __acpi_device_add(struct acpi_device *device,
void (*release)(struct device *))
{
@@ -725,6 +739,8 @@ static int __acpi_device_add(struct acpi_device *device,
if (device->wakeup.flags.valid)
list_add_tail(&device->wakeup_list, &acpi_wakeup_device_list);

+ acpi_store_pld_crc(device);
+
mutex_unlock(&acpi_device_lock);

if (device->parent)
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index 8e87ead2af341..1977db19458ed 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -356,10 +356,23 @@ struct acpi_device_data {
struct list_head subnodes;
};

+/*
+ * struct acpi_device_location - Device location based on _PLD
+ * @devices: List of devices that share this location
+ * @node: Entry in the internal list of locations
+ * @pld_crc: CRC-32 hash of the _PLD
+ */
+struct acpi_device_location {
+ struct list_head devices;
+ struct list_head node;
+ u32 pld_crc;
+};
+
struct acpi_gpio_mapping;

/* Device */
struct acpi_device {
+ u32 pld_crc;
int device_type;
acpi_handle handle; /* no handle for fixed hardware */
struct fwnode_handle fwnode;
@@ -739,7 +752,6 @@ static inline void acpi_bus_put_acpi_device(struct acpi_device *adev)

static inline int register_acpi_bus_type(void *bus) { return 0; }
static inline int unregister_acpi_bus_type(void *bus) { return 0; }
-
#endif /* CONFIG_ACPI */

#endif /*__ACPI_BUS_H__*/
--
2.34.1