lkml.org 
[lkml]   [2013]   [Jan]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 1/4] ACPI / scan: Introduce struct acpi_scan_handler
    Hi Rafael,

    2013/01/28 21:59, Rafael J. Wysocki wrote:
    > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
    >
    > Introduce struct acpi_scan_handler for representing objects that
    > will do configuration tasks depending on ACPI device nodes'
    > hardware IDs (HIDs).
    >
    > Currently, those tasks are done either directly by the ACPI namespace
    > scanning code or by ACPI device drivers designed specifically for
    > this purpose. None of the above is desirable, however, because
    > doing that directly in the namespace scanning code makes that code
    > overly complicated and difficult to follow and doing that in
    > "special" device drivers leads to a great deal of confusion about
    > their role and to confusing interactions with the driver core (for
    > example, sysfs directories are created for those drivers, but they
    > are completely unnecessary and only increase the kernel's memory
    > footprint in vain).
    >
    > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
    > ---
    Acked-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>

    I have a comment. Please see below.

    > Documentation/acpi/scan_handlers.txt | 77 +++++++++++++++++++++++++++++++++++
    > drivers/acpi/scan.c | 60 ++++++++++++++++++++++++---
    > include/acpi/acpi_bus.h | 14 ++++++
    > 3 files changed, 144 insertions(+), 7 deletions(-)
    >
    > Index: test/include/acpi/acpi_bus.h
    > ===================================================================
    > --- test.orig/include/acpi/acpi_bus.h
    > +++ test/include/acpi/acpi_bus.h
    > @@ -84,6 +84,18 @@ struct acpi_driver;
    > struct acpi_device;
    >
    > /*
    > + * ACPI Scan Handler
    > + * -----------------
    > + */
    > +
    > +struct acpi_scan_handler {
    > + const struct acpi_device_id *ids;
    > + struct list_head list_node;
    > + int (*attach)(struct acpi_device *dev, const struct acpi_device_id *id);
    > + void (*detach)(struct acpi_device *dev);
    > +};
    > +
    > +/*
    > * ACPI Driver
    > * -----------
    > */
    > @@ -269,6 +281,7 @@ struct acpi_device {
    > struct acpi_device_wakeup wakeup;
    > struct acpi_device_perf performance;
    > struct acpi_device_dir dir;
    > + struct acpi_scan_handler *handler;
    > struct acpi_driver *driver;
    > void *driver_data;
    > struct device dev;
    > @@ -382,6 +395,7 @@ int acpi_bus_receive_event(struct acpi_b
    > static inline int acpi_bus_generate_proc_event(struct acpi_device *device, u8 type, int data)
    > { return 0; }
    > #endif
    > +int acpi_scan_add_handler(struct acpi_scan_handler *handler);
    > int acpi_bus_register_driver(struct acpi_driver *driver);
    > void acpi_bus_unregister_driver(struct acpi_driver *driver);
    > int acpi_bus_scan(acpi_handle handle);
    > Index: test/drivers/acpi/scan.c
    > ===================================================================
    > --- test.orig/drivers/acpi/scan.c
    > +++ test/drivers/acpi/scan.c
    > @@ -53,6 +53,7 @@ static const struct acpi_device_id acpi_
    > static LIST_HEAD(acpi_device_list);
    > static LIST_HEAD(acpi_bus_id_list);
    > static DEFINE_MUTEX(acpi_scan_lock);
    > +static LIST_HEAD(acpi_scan_handlers_list);
    > DEFINE_MUTEX(acpi_device_lock);
    > LIST_HEAD(acpi_wakeup_device_list);
    >
    > @@ -62,6 +63,15 @@ struct acpi_device_bus_id{
    > struct list_head node;
    > };
    >
    > +int acpi_scan_add_handler(struct acpi_scan_handler *handler)
    > +{
    > + if (!handler || !handler->attach)
    > + return -EINVAL;
    > +
    > + list_add_tail(&handler->list_node, &acpi_scan_handlers_list);
    > + return 0;
    > +}
    > +
    > /*
    > * Creates hid/cid(s) string needed for modalias and uevent
    > * e.g. on a device with hid:IBM0001 and cid:ACPI0001 you get:
    > @@ -1570,20 +1580,42 @@ static acpi_status acpi_bus_check_add(ac
    > return AE_OK;
    > }
    >
    > +static int acpi_scan_attach_handler(struct acpi_device *device)
    > +{
    > + struct acpi_scan_handler *handler;
    > + int ret = 0;
    > +
    > + list_for_each_entry(handler, &acpi_scan_handlers_list, list_node) {
    > + const struct acpi_device_id *id;
    > +
    > + id = __acpi_match_device(device, handler->ids);
    > + if (!id)
    > + continue;
    > +
    > + ret = handler->attach(device, id);
    > + if (ret > 0) {
    > + device->handler = handler;
    > + break;
    > + } else if (ret < 0) {
    > + break;
    > + }
    > + }
    > + return ret;
    > +}
    > +
    > static acpi_status acpi_bus_device_attach(acpi_handle handle, u32 lvl_not_used,
    > void *not_used, void **ret_not_used)
    > {
    > const struct acpi_device_id *id;
    > - acpi_status status = AE_OK;
    > struct acpi_device *device;
    > unsigned long long sta_not_used;
    > - int type_not_used;
    > + int ret;
    >
    > /*
    > * Ignore errors ignored by acpi_bus_check_add() to avoid terminating
    > * namespace walks prematurely.
    > */
    > - if (acpi_bus_type_and_status(handle, &type_not_used, &sta_not_used))
    > + if (acpi_bus_type_and_status(handle, &ret, &sta_not_used))
    > return AE_OK;
    >
    > if (acpi_bus_get_device(handle, &device))
    > @@ -1593,10 +1625,15 @@ static acpi_status acpi_bus_device_attac
    > if (id) {
    > /* This is a known good platform device. */
    > acpi_create_platform_device(device, id->driver_data);
    > - } else if (device_attach(&device->dev) < 0) {
    > - status = AE_CTRL_DEPTH;
    > + return AE_OK;
    > }
    > - return status;
    > +

    > + ret = acpi_scan_attach_handler(device);
    > + if (ret)
    > + return ret > 0 ? AE_OK : AE_CTRL_DEPTH;

    acpi_scan_attach_hanlder() returns only 0 or -EINVAL.
    How about just return AE_CTRL_DEPTH?

    Thanks,
    Yasuaki Ishimatsu

    > +
    > + ret = device_attach(&device->dev);
    > + return ret >= 0 ? AE_OK : AE_CTRL_DEPTH;
    > }
    >
    > /**
    > @@ -1639,8 +1676,17 @@ static acpi_status acpi_bus_device_detac
    > struct acpi_device *device = NULL;
    >
    > if (!acpi_bus_get_device(handle, &device)) {
    > + struct acpi_scan_handler *dev_handler = device->handler;
    > +
    > device->removal_type = ACPI_BUS_REMOVAL_EJECT;
    > - device_release_driver(&device->dev);
    > + if (dev_handler) {
    > + if (dev_handler->detach)
    > + dev_handler->detach(device);
    > +
    > + device->handler = NULL;
    > + } else {
    > + device_release_driver(&device->dev);
    > + }
    > }
    > return AE_OK;
    > }
    > Index: test/Documentation/acpi/scan_handlers.txt
    > ===================================================================
    > --- /dev/null
    > +++ test/Documentation/acpi/scan_handlers.txt
    > @@ -0,0 +1,77 @@
    > +ACPI Scan Handlers
    > +
    > +Copyright (C) 2012, Intel Corporation
    > +Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
    > +
    > +During system initialization and ACPI-based device hot-add, the ACPI namespace
    > +is scanned in search of device objects that generally represent various pieces
    > +of hardware. This causes a struct acpi_device object to be created and
    > +registered with the driver core for every device object in the ACPI namespace
    > +and the hierarchy of those struct acpi_device objects reflects the namespace
    > +layout (i.e. parent device objects in the namespace are represented by parent
    > +struct acpi_device objects and analogously for their children). Those struct
    > +acpi_device objects are referred to as "device nodes" in what follows, but they
    > +should not be confused with struct device_node objects used by the Device Trees
    > +parsing code (although their role is analogous to the role of those objects).
    > +
    > +During ACPI-based device hot-remove device nodes representing pieces of hardware
    > +being removed are unregistered and deleted.
    > +
    > +The core ACPI namespace scanning code in drivers/acpi/scan.c carries out basic
    > +initialization of device nodes, such as retrieving common configuration
    > +information from the device objects represented by them and populating them with
    > +appropriate data, but some of them require additional handling after they have
    > +been registered. For example, if the given device node represents a PCI host
    > +bridge, its registration should cause the PCI bus under that bridge to be
    > +enumerated and PCI devices on that bus to be registered with the driver core.
    > +Similarly, if the device node represents a PCI interrupt link, it is necessary
    > +to configure that link so that the kernel can use it.
    > +
    > +Those additional configuration tasks usually depend on the type of the hardware
    > +component represented by the given device node which can be determined on the
    > +basis of the device node's hardware ID (HID). They are performed by objects
    > +called ACPI scan handlers represented by the following structure:
    > +
    > +struct acpi_scan_handler {
    > + const struct acpi_device_id *ids;
    > + struct list_head list_node;
    > + int (*attach)(struct acpi_device *dev, const struct acpi_device_id *id);
    > + void (*detach)(struct acpi_device *dev);
    > +};
    > +
    > +where ids is the list of IDs of device nodes the given handler is supposed to
    > +take care of, list_node is the hook to the global list of ACPI scan handlers
    > +maintained by the ACPI core and the .attach() and .detach() callbacks are
    > +executed, respectively, after registration of new device nodes and before
    > +unregistration of device nodes the handler attached to previously.
    > +
    > +The namespace scanning function, acpi_bus_scan(), first registers all of the
    > +device nodes in the given namespace scope with the driver core. Then, it tries
    > +to match a scan handler against each of them using the ids arrays of the
    > +available scan handlers. If a matching scan handler is found, its .attach()
    > +callback is executed for the given device node. If that callback returns 1,
    > +that means that the handler has claimed the device node and is now responsible
    > +for carrying out any additional configuration tasks related to it. It also will
    > +be responsible for preparing the device node for unregistration in that case.
    > +The device node's handler field is then populated with the address of the scan
    > +handler that has claimed it.
    > +
    > +If the .attach() callback returns 0, it means that the device node is not
    > +interesting to the given scan handler and may be matched against the next scan
    > +handler in the list. If it returns a (negative) error code, that means that
    > +the namespace scan should be terminated due to a serious error. The error code
    > +returned should then reflect the type of the error.
    > +
    > +The namespace trimming function, acpi_bus_trim(), first executes .detach()
    > +callbacks from the scan handlers of all device nodes in the given namespace
    > +scope (if they have scan handlers). Next, it unregisters all of the device
    > +nodes in that scope.
    > +
    > +ACPI scan handlers can be added to the list maintained by the ACPI core with the
    > +help of the acpi_scan_add_handler() function taking a pointer to the new scan
    > +handler as an argument. The order in which scan handlers are added to the list
    > +is the order in which they are matched against device nodes during namespace
    > +scans.
    > +
    > +All scan handles must be added to the list before acpi_bus_scan() is run for the
    > +first time and they cannot be removed from it.
    >
    > --
    > To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
    > the body of a message to majordomo@vger.kernel.org
    > More majordomo info at http://vger.kernel.org/majordomo-info.html
    >




    \
     
     \ /
      Last update: 2013-01-29 03:41    [W:6.488 / U:0.916 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site