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