From a4ff342afe2d05c6bb8f479b51c7365412763e9c Mon Sep 17 00:00:00 2001 From: Patrick Mochel <mochel@osdl.org> Date: Mon, 9 Jun 2003 02:40:02 -0700 Subject: [PATCH] [driver model] Rewrite system device API System devices are special, and after two years of listening to Linus preach this, it finally sunk in enough to do something about. We don't need to regard them as real devices that reside on a peripheral bus and can be dynamically bound to drivers. If we discover, e.g. a CPU, we know by default that we have a driver for it, and we know damn well that we have a CPU. We still need to keep track of all the devices, and all the devices of a particular type. The kobject infrastructure allows us to do this, without the overhead of the regular model. A new subsystem is defined that registers as a child object of devices_subsys, giving us: /sys/devices/system/ struct sysdev_class { struct list_head drivers; /* Default operations for these types of devices */ int (*shutdown)(struct sys_device *); int (*suspend)(struct sys_device *, u32 state); int (*resume)(struct sys_device *); struct kset kset; }; Defines a type of system device. These are registered on startup, by e.g. drivers/base/cpu.c. The methods are default operations for devices of that type that may or may not be used. For things like the i8259 controller, these will be filled in, since it is registered by the same component that the device controls reside in. For things like CPUs, generic code will register the class, but other architecture-specific or otherwise configurable drivers may register auxillary drivers, that look like: struct sysdev_driver { struct list_head entry; int (*add)(struct sys_device *); int (*remove)(struct sys_device *); int (*shutdown)(struct sys_device *); int (*suspend)(struct sys_device *, u32 state); int (*resume)(struct sys_device *); }; Each auxillary driver gets called during each operation on a device of a particular class. Auxillary drivers may register with a NULL class parameter, in which case they will be added to a list of 'global drivers' that get called for each device of each class. Besides providing a decent of cleanup for system device drivers, this also allows: - Special handling of system devices during power transitions. We no longer have to worry about shutting down the PIC before we shut down any devices. We can shut down the system devices after we've shut down every other device. Ditto for suspend/resume cycles. Almost (if not) all PM actions for system devices happen with interrupts off, and require only one call, which makes that easier. But, we can also make sure we take care of these last during suspend and first during resume. - Easy expression of configurable device-specific interfaces. Namely cpufreq and mtrr. We don't have to worry about mispresentation in the driver model (like recent MTRR patches) or using a cumbersome interface ({device,class}_interface) that don't receive all the necessary calls. - Consolidation of userspace representation. No longer do we have /sys/devices/sys, /sys/bus/sys, and /sys/class/cpu, etc. We have only /sys/devices/system: # tree /sys/devices/system/ /sys/devices/system/ |-- cpu | `-- cpu0 |-- i8259 | `-- i82590 |-- lapic | `-- lapic0 |-- rtc | `-- rtc0 `-- timer `-- timer0 Each directory in 'system' is the class, and each directory under that is the instance of each device in that class. --- drivers/base/sys.c | 343 +++++++++++++++++++++++++++++++---------- include/linux/device.h | 68 ++++++-- 2 files changed, 318 insertions(+), 93 deletions(-) diff --git a/drivers/base/sys.c b/drivers/base/sys.c index 5ae457170548..aa71e40a865e 100644 --- a/drivers/base/sys.c +++ b/drivers/base/sys.c @@ -12,7 +12,7 @@ * add themselves as children of the system bus. */ -#undef DEBUG +#define DEBUG #include <linux/device.h> #include <linux/err.h> @@ -22,130 +22,307 @@ #include <linux/slab.h> #include <linux/string.h> -/* The default system device parent. */ -static struct device system_bus = { - .name = "System Bus", - .bus_id = "sys", -}; +extern struct subsystem devices_subsys; + +/* + * declare system_subsys + */ +decl_subsys(system,NULL,NULL); + +int sysdev_class_register(struct sysdev_class * cls) +{ + pr_debug("Registering sysdev class '%s'\n",cls->kset.kobj.name); + INIT_LIST_HEAD(&cls->drivers); + cls->kset.subsys = &system_subsys; + kset_set_kset_s(cls,system_subsys); + return kset_register(&cls->kset); +} + +void sysdev_class_unregister(struct sysdev_class * cls) +{ + pr_debug("Unregistering sysdev class '%s'\n",cls->kset.kobj.name); + kset_unregister(&cls->kset); +} + +EXPORT_SYMBOL(sysdev_class_register); +EXPORT_SYMBOL(sysdev_class_unregister); + + +static LIST_HEAD(global_drivers); /** - * sys_register_root - add a subordinate system root - * @root: new root - * - * This is for NUMA-like systems so they can accurately - * represent the topology of the entire system. - * As boards are discovered, a new struct sys_root should - * be allocated and registered. - * The discovery mechanism should initialize the id field - * of the struture, as well as much of the embedded device - * structure as possible, inlcuding the name, the bus_id - * and parent fields. + * sysdev_driver_register - Register auxillary driver + * @cls: Device class driver belongs to. + * @drv: Driver. * - * This simply calls device_register on the embedded device. - * On success, it will use the struct @root->sysdev - * device to create a pseudo-parent for system devices - * on that board. + * If @cls is valid, then @drv is inserted into @cls->drivers to be + * called on each operation on devices of that class. The refcount + * of @cls is incremented. + * Otherwise, @drv is inserted into global_drivers, and called for + * each device. + */ + +int sysdev_driver_register(struct sysdev_class * cls, + struct sysdev_driver * drv) +{ + down_write(&system_subsys.rwsem); + if (kset_get(&cls->kset)) + list_add_tail(&drv->entry,&cls->drivers); + else + list_add_tail(&drv->entry,&global_drivers); + up_write(&system_subsys.rwsem); + return 0; +} + + +/** + * sysdev_driver_unregister - Remove an auxillary driver. + * @cls: Class driver belongs to. + * @drv: Driver. + */ +void sysdev_driver_unregister(struct sysdev_class * cls, + struct sysdev_driver * drv) +{ + down_write(&system_subsys.rwsem); + list_del_init(&drv->entry); + if (cls) + kset_put(&cls->kset); + up_write(&system_subsys.rwsem); +} + + +/** + * sys_device_register - add a system device to the tree + * @sysdev: device in question * - * The platform code can then use @root to specifiy the - * controlling board when discovering and registering - * system devices. */ -int sys_register_root(struct sys_root * root) +int sys_device_register(struct sys_device * sysdev) { - int error = 0; + int error; + struct sysdev_class * cls = sysdev->cls; - if (!root) + if (!cls) return -EINVAL; - if (!root->dev.parent) - root->dev.parent = &system_bus; + /* Make sure the kset is set */ + sysdev->kobj.kset = &cls->kset; + + /* set the kobject name */ + snprintf(sysdev->kobj.name,KOBJ_NAME_LEN,"%s%d", + cls->kset.kobj.name,sysdev->id); + + pr_debug("Registering sys device '%s'\n",sysdev->kobj.name); - pr_debug("Registering system board %d\n",root->id); + /* Register the object */ + error = kobject_register(&sysdev->kobj); - error = device_register(&root->dev); if (!error) { - strlcpy(root->sysdev.bus_id,"sys",BUS_ID_SIZE); - strlcpy(root->sysdev.name,"System Bus",DEVICE_NAME_SIZE); - root->sysdev.parent = &root->dev; - error = device_register(&root->sysdev); - }; + struct sysdev_driver * drv; + + down_read(&system_subsys.rwsem); + /* Generic notification is implicit, because it's that + * code that should have called us. + */ + + /* Notify global drivers */ + list_for_each_entry(drv,&global_drivers,entry) { + if (drv->add) + drv->add(sysdev); + } + /* Notify class auxillary drivers */ + list_for_each_entry(drv,&cls->drivers,entry) { + if (drv->add) + drv->add(sysdev); + } + up_read(&system_subsys.rwsem); + } return error; } +void sys_device_unregister(struct sys_device * sysdev) +{ + struct sysdev_driver * drv; + + down_read(&system_subsys.rwsem); + list_for_each_entry(drv,&global_drivers,entry) { + if (drv->remove) + drv->remove(sysdev); + } + + list_for_each_entry(drv,&sysdev->cls->drivers,entry) { + if (drv->remove) + drv->remove(sysdev); + } + up_read(&system_subsys.rwsem); + + kobject_unregister(&sysdev->kobj); +} + + + /** - * sys_unregister_root - remove subordinate root from tree - * @root: subordinate root in question. + * sys_device_shutdown - Shut down all system devices. + * + * Loop over each class of system devices, and the devices in each + * of those classes. For each device, we call the shutdown method for + * each driver registered for the device - the globals, the auxillaries, + * and the class driver. * - * We only decrement the reference count on @root->sysdev - * and @root->dev. - * If both are 0, they will be cleaned up by the core. + * Note: The list is iterated in reverse order, so that we shut down + * child devices before we shut down thier parents. The list ordering + * is guaranteed by virtue of the fact that child devices are registered + * after their parents. */ -void sys_unregister_root(struct sys_root *root) + +void sys_device_shutdown(void) { - device_unregister(&root->sysdev); - device_unregister(&root->dev); + struct sysdev_class * cls; + + pr_debug("Shutting Down System Devices\n"); + + down_write(&system_subsys.rwsem); + list_for_each_entry_reverse(cls,&system_subsys.kset.list, + kset.kobj.entry) { + struct sys_device * sysdev; + + pr_debug("Shutting down type '%s':\n",cls->kset.kobj.name); + + list_for_each_entry(sysdev,&cls->kset.list,kobj.entry) { + struct sysdev_driver * drv; + pr_debug(" %s\n",sysdev->kobj.name); + + /* Call global drivers first. */ + list_for_each_entry(drv,&global_drivers,entry) { + if (drv->shutdown) + drv->shutdown(sysdev); + } + + /* Call auxillary drivers next. */ + list_for_each_entry(drv,&cls->drivers,entry) { + if (drv->shutdown) + drv->shutdown(sysdev); + } + + /* Now call the generic one */ + if (cls->shutdown) + cls->shutdown(sysdev); + } + } + up_write(&system_subsys.rwsem); } + /** - * sys_device_register - add a system device to the tree - * @sysdev: device in question - * - * The hardest part about this is getting the ancestry right. - * If the device has a parent - super! We do nothing. - * If the device doesn't, but @dev->root is set, then we're - * dealing with a NUMA like architecture where each root - * has a system pseudo-bus to foster the device. - * If not, then we fallback to system_bus (at the top of - * this file). + * sys_device_suspend - Suspend all system devices. + * @state: Power state to enter. * - * One way or another, we call device_register() on it and - * are done. + * We perform an almost identical operation as sys_device_shutdown() + * above, though calling ->suspend() instead. * - * The caller is also responsible for initializing the bus_id - * and name fields of @sysdev->dev. + * Note: Interrupts are disabled when called, so we can't sleep when + * trying to get the subsystem's rwsem. If that happens, print a nasty + * warning and return an error. */ -int sys_device_register(struct sys_device * sysdev) + +int sys_device_suspend(u32 state) { - if (!sysdev) - return -EINVAL; + struct sysdev_class * cls; - if (!sysdev->dev.parent) { - if (sysdev->root) - sysdev->dev.parent = &sysdev->root->sysdev; - else - sysdev->dev.parent = &system_bus; + pr_debug("Suspending System Devices\n"); + + if (!down_write_trylock(&system_subsys.rwsem)) { + printk("%s: Cannot acquire semaphore; Failing\n",__FUNCTION__); + return -EFAULT; } - /* make sure bus type is set */ - if (!sysdev->dev.bus) - sysdev->dev.bus = &system_bus_type; + list_for_each_entry_reverse(cls,&system_subsys.kset.list, + kset.kobj.entry) { + struct sys_device * sysdev; + + pr_debug("Suspending type '%s':\n",cls->kset.kobj.name); - /* construct bus_id */ - snprintf(sysdev->dev.bus_id,BUS_ID_SIZE,"%s%u",sysdev->name,sysdev->id); + list_for_each_entry(sysdev,&cls->kset.list,kobj.entry) { + struct sysdev_driver * drv; + pr_debug(" %s\n",sysdev->kobj.name); - pr_debug("Registering system device %s\n", sysdev->dev.bus_id); + /* Call global drivers first. */ + list_for_each_entry(drv,&global_drivers,entry) { + if (drv->suspend) + drv->suspend(sysdev,state); + } - return device_register(&sysdev->dev); + /* Call auxillary drivers next. */ + list_for_each_entry(drv,&cls->drivers,entry) { + if (drv->suspend) + drv->suspend(sysdev,state); + } + + /* Now call the generic one */ + if (cls->suspend) + cls->suspend(sysdev,state); + } + } + up_write(&system_subsys.rwsem); + + return 0; } -void sys_device_unregister(struct sys_device * sysdev) + +/** + * sys_device_resume - Bring system devices back to life. + * + * Similar to sys_device_suspend(), but we iterate the list forwards + * to guarantee that parent devices are resumed before their children. + * + * Note: Interrupts are disabled when called. + */ + +int sys_device_resume(void) { - if (sysdev) - device_unregister(&sysdev->dev); -} + struct sysdev_class * cls; + + pr_debug("Resuming System Devices\n"); + + if(!down_write_trylock(&system_subsys.rwsem)) + return -EFAULT; + + list_for_each_entry(cls,&system_subsys.kset.list,kset.kobj.entry) { + struct sys_device * sysdev; + + pr_debug("Resuming type '%s':\n",cls->kset.kobj.name); -struct bus_type system_bus_type = { - .name = "system", -}; + list_for_each_entry(sysdev,&cls->kset.list,kobj.entry) { + struct sysdev_driver * drv; + pr_debug(" %s\n",sysdev->kobj.name); + + /* Call global drivers first. */ + list_for_each_entry(drv,&global_drivers,entry) { + if (drv->resume) + drv->resume(sysdev); + } + + /* Call auxillary drivers next. */ + list_for_each_entry(drv,&cls->drivers,entry) { + if (drv->resume) + drv->resume(sysdev); + } + + /* Now call the generic one */ + if (cls->resume) + cls->resume(sysdev); + } + } + up_write(&system_subsys.rwsem); + return 0; +} int __init sys_bus_init(void) { - bus_register(&system_bus_type); - return device_register(&system_bus); + system_subsys.kset.kobj.parent = &devices_subsys.kset.kobj; + return subsystem_register(&system_subsys); } -EXPORT_SYMBOL(system_bus_type); EXPORT_SYMBOL(sys_device_register); EXPORT_SYMBOL(sys_device_unregister); diff --git a/include/linux/device.h b/include/linux/device.h index 3604d351f3f0..de674eaea31c 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -351,24 +351,72 @@ extern int (*platform_notify_remove)(struct device * dev); extern struct device * get_device(struct device * dev); extern void put_device(struct device * dev); + /* drivers/base/sys.c */ -struct sys_root { - u32 id; - struct device dev; - struct device sysdev; +/** + * System devices follow a slightly different driver model. + * They don't need to do dynammic driver binding, can't be probed, + * and don't reside on any type of peripheral bus. + * So, we represent and treat them a little differently. + * + * We still have a notion of a driver for a system device, because we still + * want to perform basic operations on these devices. + * + * We also support auxillary drivers binding to devices of a certain class. + * + * This allows configurable drivers to register themselves for devices of + * a certain type. And, it allows class definitions to reside in generic + * code while arch-specific code can register specific drivers. + * + * Auxillary drivers registered with a NULL cls are registered as drivers + * for all system devices, and get notification calls for each device. + */ + +struct sys_device; + +struct sysdev_class { + struct list_head drivers; + + /* Default operations for these types of devices */ + int (*shutdown)(struct sys_device *); + int (*suspend)(struct sys_device *, u32 state); + int (*resume)(struct sys_device *); + struct kset kset; +}; + + +extern int sysdev_class_register(struct sysdev_class *); +extern void sysdev_class_unregister(struct sysdev_class *); + + +/** + * Auxillary system device drivers. + */ + +struct sysdev_driver { + struct list_head entry; + int (*add)(struct sys_device *); + int (*remove)(struct sys_device *); + int (*shutdown)(struct sys_device *); + int (*suspend)(struct sys_device *, u32 state); + int (*resume)(struct sys_device *); }; -extern int sys_register_root(struct sys_root *); -extern void sys_unregister_root(struct sys_root *); + +extern int sysdev_driver_register(struct sysdev_class *, struct sysdev_driver *); +extern void sysdev_driver_unregister(struct sysdev_class *, struct sysdev_driver *); +/** + * sys_devices can be simplified a lot from regular devices, because they're + * simply not as versatile. + */ + struct sys_device { - char * name; u32 id; - struct sys_root * root; - struct device dev; - struct class_device class_dev; + struct sysdev_class * cls; + struct kobject kobj; }; extern int sys_device_register(struct sys_device *); -- 2.30.9