--- /dev/null
+/*
+ * driver.c - driver support
+ *
+ * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
+ * Shaohua Li <shaohua.li@intel.com>
+ * Adam Belay <abelay@novell.com>
+ *
+ * This code is licenced under the GPL.
+ */
+
+#include <linux/mutex.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/cpuidle.h>
+#include <linux/cpumask.h>
+#include <linux/tick.h>
+
+#include "cpuidle.h"
+
+DEFINE_SPINLOCK(cpuidle_driver_lock);
+
+#ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS
+
+static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers);
+
+/**
+ * __cpuidle_get_cpu_driver - return the cpuidle driver tied to a CPU.
+ * @cpu: the CPU handled by the driver
+ *
+ * Returns a pointer to struct cpuidle_driver or NULL if no driver has been
+ * registered for @cpu.
+ */
+static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
+{
+ return per_cpu(cpuidle_drivers, cpu);
+}
+
+/**
+ * __cpuidle_unset_driver - unset per CPU driver variables.
+ * @drv: a valid pointer to a struct cpuidle_driver
+ *
+ * For each CPU in the driver's CPU mask, unset the registered driver per CPU
+ * variable. If @drv is different from the registered driver, the corresponding
+ * variable is not cleared.
+ */
+static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)
+{
+ int cpu;
+
+ for_each_cpu(cpu, drv->cpumask) {
+
+ if (drv != __cpuidle_get_cpu_driver(cpu))
+ continue;
+
+ per_cpu(cpuidle_drivers, cpu) = NULL;
+ }
+}
+
+/**
+ * __cpuidle_set_driver - set per CPU driver variables for the given driver.
+ * @drv: a valid pointer to a struct cpuidle_driver
+ *
+ * For each CPU in the driver's cpumask, unset the registered driver per CPU
+ * to @drv.
+ *
+ * Returns 0 on success, -EBUSY if the CPUs have driver(s) already.
+ */
+static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
+{
+ int cpu;
+
+ for_each_cpu(cpu, drv->cpumask) {
+
+ if (__cpuidle_get_cpu_driver(cpu)) {
+ __cpuidle_unset_driver(drv);
+ return -EBUSY;
+ }
+
+ per_cpu(cpuidle_drivers, cpu) = drv;
+ }
+
+ return 0;
+}
+
+#else
+
+static struct cpuidle_driver *cpuidle_curr_driver;
+
+/**
+ * __cpuidle_get_cpu_driver - return the global cpuidle driver pointer.
+ * @cpu: ignored without the multiple driver support
+ *
+ * Return a pointer to a struct cpuidle_driver object or NULL if no driver was
+ * previously registered.
+ */
+static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
+{
+ return cpuidle_curr_driver;
+}
+
+/**
+ * __cpuidle_set_driver - assign the global cpuidle driver variable.
+ * @drv: pointer to a struct cpuidle_driver object
+ *
+ * Returns 0 on success, -EBUSY if the driver is already registered.
+ */
+static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
+{
+ if (cpuidle_curr_driver)
+ return -EBUSY;
+
+ cpuidle_curr_driver = drv;
+
+ return 0;
+}
+
+/**
+ * __cpuidle_unset_driver - unset the global cpuidle driver variable.
+ * @drv: a pointer to a struct cpuidle_driver
+ *
+ * Reset the global cpuidle variable to NULL. If @drv does not match the
+ * registered driver, do nothing.
+ */
+static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)
+{
+ if (drv == cpuidle_curr_driver)
+ cpuidle_curr_driver = NULL;
+}
+
+#endif
+
+/**
+ * cpuidle_setup_broadcast_timer - enable/disable the broadcast timer on a cpu
+ * @arg: a void pointer used to match the SMP cross call API
+ *
+ * If @arg is NULL broadcast is disabled otherwise enabled
+ *
+ * This function is executed per CPU by an SMP cross call. It's not
+ * supposed to be called directly.
+ */
+static void cpuidle_setup_broadcast_timer(void *arg)
+{
+ if (arg)
+ tick_broadcast_enable();
+ else
+ tick_broadcast_disable();
+}
+
+/**
+ * __cpuidle_driver_init - initialize the driver's internal data
+ * @drv: a valid pointer to a struct cpuidle_driver
+ */
+static void __cpuidle_driver_init(struct cpuidle_driver *drv)
+{
+ int i;
+
+ drv->refcnt = 0;
+
+ /*
+ * Use all possible CPUs as the default, because if the kernel boots
+ * with some CPUs offline and then we online one of them, the CPU
+ * notifier has to know which driver to assign.
+ */
+ if (!drv->cpumask)
+ drv->cpumask = (struct cpumask *)cpu_possible_mask;
+
+ /*
+ * Look for the timer stop flag in the different states, so that we know
+ * if the broadcast timer has to be set up. The loop is in the reverse
+ * order, because usually one of the deeper states have this flag set.
+ */
+ for (i = drv->state_count - 1; i >= 0 ; i--) {
+ if (drv->states[i].flags & CPUIDLE_FLAG_TIMER_STOP) {
+ drv->bctimer = 1;
+ break;
+ }
+ }
+}
+
+#ifdef CONFIG_ARCH_HAS_CPU_RELAX
+static int poll_idle(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv, int index)
+{
+ local_irq_enable();
+ if (!current_set_polling_and_test()) {
+ while (!need_resched())
+ cpu_relax();
+ }
+ current_clr_polling();
+
+ return index;
+}
+
+static void poll_idle_init(struct cpuidle_driver *drv)
+{
+ struct cpuidle_state *state = &drv->states[0];
+
+ snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
+ snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
+ state->exit_latency = 0;
+ state->target_residency = 0;
+ state->power_usage = -1;
+ state->enter = poll_idle;
+ state->disabled = false;
+}
+#else
+static void poll_idle_init(struct cpuidle_driver *drv) {}
+#endif /* !CONFIG_ARCH_HAS_CPU_RELAX */
+
+/**
+ * __cpuidle_register_driver: register the driver
+ * @drv: a valid pointer to a struct cpuidle_driver
+ *
+ * Do some sanity checks, initialize the driver, assign the driver to the
+ * global cpuidle driver variable(s) and set up the broadcast timer if the
+ * cpuidle driver has some states that shut down the local timer.
+ *
+ * Returns 0 on success, a negative error code otherwise:
+ * * -EINVAL if the driver pointer is NULL or no idle states are available
+ * * -ENODEV if the cpuidle framework is disabled
+ * * -EBUSY if the driver is already assigned to the global variable(s)
+ */
+static int __cpuidle_register_driver(struct cpuidle_driver *drv)
+{
+ int ret;
+
+ if (!drv || !drv->state_count)
+ return -EINVAL;
+
+ if (cpuidle_disabled())
+ return -ENODEV;
+
+ __cpuidle_driver_init(drv);
+
+ ret = __cpuidle_set_driver(drv);
+ if (ret)
+ return ret;
+
+ if (drv->bctimer)
+ on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
+ (void *)1, 1);
+
+ poll_idle_init(drv);
+
+ return 0;
+}
+
+/**
+ * __cpuidle_unregister_driver - unregister the driver
+ * @drv: a valid pointer to a struct cpuidle_driver
+ *
+ * Check if the driver is no longer in use, reset the global cpuidle driver
+ * variable(s) and disable the timer broadcast notification mechanism if it was
+ * in use.
+ *
+ */
+static void __cpuidle_unregister_driver(struct cpuidle_driver *drv)
+{
+ if (WARN_ON(drv->refcnt > 0))
+ return;
+
+ if (drv->bctimer) {
+ drv->bctimer = 0;
+ on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
+ NULL, 1);
+ }
+
+ __cpuidle_unset_driver(drv);
+}
+
+/**
+ * cpuidle_register_driver - registers a driver
+ * @drv: a pointer to a valid struct cpuidle_driver
+ *
+ * Register the driver under a lock to prevent concurrent attempts to
+ * [un]register the driver from occuring at the same time.
+ *
+ * Returns 0 on success, a negative error code (returned by
+ * __cpuidle_register_driver()) otherwise.
+ */
+int cpuidle_register_driver(struct cpuidle_driver *drv)
+{
+ int ret;
+
+ spin_lock(&cpuidle_driver_lock);
+ ret = __cpuidle_register_driver(drv);
+ spin_unlock(&cpuidle_driver_lock);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(cpuidle_register_driver);
+
+/**
+ * cpuidle_unregister_driver - unregisters a driver
+ * @drv: a pointer to a valid struct cpuidle_driver
+ *
+ * Unregisters the cpuidle driver under a lock to prevent concurrent attempts
+ * to [un]register the driver from occuring at the same time. @drv has to
+ * match the currently registered driver.
+ */
+void cpuidle_unregister_driver(struct cpuidle_driver *drv)
+{
+ spin_lock(&cpuidle_driver_lock);
+ __cpuidle_unregister_driver(drv);
+ spin_unlock(&cpuidle_driver_lock);
+}
+EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
+
+/**
+ * cpuidle_get_driver - return the driver tied to the current CPU.
+ *
+ * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered.
+ */
+struct cpuidle_driver *cpuidle_get_driver(void)
+{
+ struct cpuidle_driver *drv;
+ int cpu;
+
+ cpu = get_cpu();
+ drv = __cpuidle_get_cpu_driver(cpu);
+ put_cpu();
+
+ return drv;
+}
+EXPORT_SYMBOL_GPL(cpuidle_get_driver);
+
+/**
+ * cpuidle_get_cpu_driver - return the driver registered for a CPU.
+ * @dev: a valid pointer to a struct cpuidle_device
+ *
+ * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered
+ * for the CPU associated with @dev.
+ */
+struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev)
+{
+ if (!dev)
+ return NULL;
+
+ return __cpuidle_get_cpu_driver(dev->cpu);
+}
+EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver);
+
+/**
+ * cpuidle_driver_ref - get a reference to the driver.
+ *
+ * Increment the reference counter of the cpuidle driver associated with
+ * the current CPU.
+ *
+ * Returns a pointer to the driver, or NULL if the current CPU has no driver.
+ */
+struct cpuidle_driver *cpuidle_driver_ref(void)
+{
+ struct cpuidle_driver *drv;
+
+ spin_lock(&cpuidle_driver_lock);
+
+ drv = cpuidle_get_driver();
+ if (drv)
+ drv->refcnt++;
+
+ spin_unlock(&cpuidle_driver_lock);
+ return drv;
+}
+
+/**
+ * cpuidle_driver_unref - puts down the refcount for the driver
+ *
+ * Decrement the reference counter of the cpuidle driver associated with
+ * the current CPU.
+ */
+void cpuidle_driver_unref(void)
+{
+ struct cpuidle_driver *drv;
+
+ spin_lock(&cpuidle_driver_lock);
+
+ drv = cpuidle_get_driver();
+ if (drv && !WARN_ON(drv->refcnt <= 0))
+ drv->refcnt--;
+
+ spin_unlock(&cpuidle_driver_lock);
+}
Code Review / kvmfornfv.git / blobdiff