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![preeti](/assets/img/avatar_default.png)
On some archs, the local clockevent device stops in deep cpuidle states. The broadcast framework is used to wakeup cpus in these idle states, in which either an external clockevent device is used to send wakeup ipis or the hrtimer broadcast framework kicks in in the absence of such a device. One cpu is nominated as the broadcast cpu and this cpu sends wakeup ipis to sleeping cpus at the appropriate time. This is the implementation in the oneshot mode of broadcast. In periodic mode of broadcast however, the presence of such cpuidle states results in the cpuidle driver calling tick_broadcast_enable() which shuts down the local clockevent devices of all the cpus and appoints the tick broadcast device as the clockevent device for each of them. This works on those archs where the tick broadcast device is a real clockevent device. But on archs which depend on the hrtimer mode of broadcast, the tick broadcast device hapens to be a pseudo device. The consequence is that the local clockevent devices of all cpus are shutdown and the kernel hangs at boot time in periodic mode. Let us thus not register the cpuidle states which have CPUIDLE_FLAG_TIMER_STOP flag set, on archs which depend on the hrtimer mode of broadcast in periodic mode. This patch takes care of doing this on powerpc. The cpus would not have entered into such deep cpuidle states in periodic mode on powerpc anyway. So there is no loss here. Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: 3.19+ <stable@vger.kernel.org> # 3.19+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
302 lines
7.2 KiB
C
302 lines
7.2 KiB
C
/*
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* cpuidle-powernv - idle state cpuidle driver.
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* Adapted from drivers/cpuidle/cpuidle-pseries
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*
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/moduleparam.h>
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#include <linux/cpuidle.h>
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#include <linux/cpu.h>
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#include <linux/notifier.h>
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#include <linux/clockchips.h>
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#include <linux/of.h>
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#include <linux/slab.h>
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#include <asm/machdep.h>
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#include <asm/firmware.h>
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#include <asm/opal.h>
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#include <asm/runlatch.h>
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#define MAX_POWERNV_IDLE_STATES 8
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struct cpuidle_driver powernv_idle_driver = {
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.name = "powernv_idle",
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.owner = THIS_MODULE,
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};
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static int max_idle_state;
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static struct cpuidle_state *cpuidle_state_table;
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static u64 snooze_timeout;
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static bool snooze_timeout_en;
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static int snooze_loop(struct cpuidle_device *dev,
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struct cpuidle_driver *drv,
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int index)
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{
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u64 snooze_exit_time;
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local_irq_enable();
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set_thread_flag(TIF_POLLING_NRFLAG);
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snooze_exit_time = get_tb() + snooze_timeout;
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ppc64_runlatch_off();
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while (!need_resched()) {
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HMT_low();
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HMT_very_low();
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if (snooze_timeout_en && get_tb() > snooze_exit_time)
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break;
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}
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HMT_medium();
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ppc64_runlatch_on();
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clear_thread_flag(TIF_POLLING_NRFLAG);
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smp_mb();
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return index;
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}
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static int nap_loop(struct cpuidle_device *dev,
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struct cpuidle_driver *drv,
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int index)
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{
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ppc64_runlatch_off();
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power7_idle();
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ppc64_runlatch_on();
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return index;
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}
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/* Register for fastsleep only in oneshot mode of broadcast */
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#ifdef CONFIG_TICK_ONESHOT
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static int fastsleep_loop(struct cpuidle_device *dev,
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struct cpuidle_driver *drv,
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int index)
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{
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unsigned long old_lpcr = mfspr(SPRN_LPCR);
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unsigned long new_lpcr;
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if (unlikely(system_state < SYSTEM_RUNNING))
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return index;
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new_lpcr = old_lpcr;
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/* Do not exit powersave upon decrementer as we've setup the timer
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* offload.
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*/
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new_lpcr &= ~LPCR_PECE1;
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mtspr(SPRN_LPCR, new_lpcr);
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power7_sleep();
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mtspr(SPRN_LPCR, old_lpcr);
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return index;
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}
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#endif
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/*
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* States for dedicated partition case.
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*/
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static struct cpuidle_state powernv_states[MAX_POWERNV_IDLE_STATES] = {
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{ /* Snooze */
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.name = "snooze",
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.desc = "snooze",
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.exit_latency = 0,
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.target_residency = 0,
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.enter = &snooze_loop },
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};
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static int powernv_cpuidle_add_cpu_notifier(struct notifier_block *n,
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unsigned long action, void *hcpu)
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{
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int hotcpu = (unsigned long)hcpu;
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struct cpuidle_device *dev =
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per_cpu(cpuidle_devices, hotcpu);
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if (dev && cpuidle_get_driver()) {
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switch (action) {
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case CPU_ONLINE:
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case CPU_ONLINE_FROZEN:
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cpuidle_pause_and_lock();
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cpuidle_enable_device(dev);
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cpuidle_resume_and_unlock();
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break;
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case CPU_DEAD:
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case CPU_DEAD_FROZEN:
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cpuidle_pause_and_lock();
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cpuidle_disable_device(dev);
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cpuidle_resume_and_unlock();
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break;
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default:
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return NOTIFY_DONE;
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}
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}
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return NOTIFY_OK;
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}
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static struct notifier_block setup_hotplug_notifier = {
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.notifier_call = powernv_cpuidle_add_cpu_notifier,
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};
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/*
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* powernv_cpuidle_driver_init()
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*/
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static int powernv_cpuidle_driver_init(void)
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{
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int idle_state;
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struct cpuidle_driver *drv = &powernv_idle_driver;
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drv->state_count = 0;
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for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
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/* Is the state not enabled? */
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if (cpuidle_state_table[idle_state].enter == NULL)
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continue;
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drv->states[drv->state_count] = /* structure copy */
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cpuidle_state_table[idle_state];
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drv->state_count += 1;
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}
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return 0;
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}
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static int powernv_add_idle_states(void)
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{
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struct device_node *power_mgt;
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int nr_idle_states = 1; /* Snooze */
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int dt_idle_states;
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u32 *latency_ns, *residency_ns, *flags;
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int i, rc;
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/* Currently we have snooze statically defined */
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power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
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if (!power_mgt) {
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pr_warn("opal: PowerMgmt Node not found\n");
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goto out;
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}
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/* Read values of any property to determine the num of idle states */
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dt_idle_states = of_property_count_u32_elems(power_mgt, "ibm,cpu-idle-state-flags");
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if (dt_idle_states < 0) {
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pr_warn("cpuidle-powernv: no idle states found in the DT\n");
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goto out;
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}
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flags = kzalloc(sizeof(*flags) * dt_idle_states, GFP_KERNEL);
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if (of_property_read_u32_array(power_mgt,
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"ibm,cpu-idle-state-flags", flags, dt_idle_states)) {
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pr_warn("cpuidle-powernv : missing ibm,cpu-idle-state-flags in DT\n");
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goto out_free_flags;
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}
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latency_ns = kzalloc(sizeof(*latency_ns) * dt_idle_states, GFP_KERNEL);
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rc = of_property_read_u32_array(power_mgt,
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"ibm,cpu-idle-state-latencies-ns", latency_ns, dt_idle_states);
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if (rc) {
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pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-latencies-ns in DT\n");
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goto out_free_latency;
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}
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residency_ns = kzalloc(sizeof(*residency_ns) * dt_idle_states, GFP_KERNEL);
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rc = of_property_read_u32_array(power_mgt,
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"ibm,cpu-idle-state-residency-ns", residency_ns, dt_idle_states);
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for (i = 0; i < dt_idle_states; i++) {
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/*
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* Cpuidle accepts exit_latency and target_residency in us.
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* Use default target_residency values if f/w does not expose it.
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*/
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if (flags[i] & OPAL_PM_NAP_ENABLED) {
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/* Add NAP state */
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strcpy(powernv_states[nr_idle_states].name, "Nap");
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strcpy(powernv_states[nr_idle_states].desc, "Nap");
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powernv_states[nr_idle_states].flags = 0;
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powernv_states[nr_idle_states].target_residency = 100;
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powernv_states[nr_idle_states].enter = &nap_loop;
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}
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/*
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* All cpuidle states with CPUIDLE_FLAG_TIMER_STOP set must come
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* within this config dependency check.
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*/
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#ifdef CONFIG_TICK_ONESHOT
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if (flags[i] & OPAL_PM_SLEEP_ENABLED ||
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flags[i] & OPAL_PM_SLEEP_ENABLED_ER1) {
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/* Add FASTSLEEP state */
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strcpy(powernv_states[nr_idle_states].name, "FastSleep");
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strcpy(powernv_states[nr_idle_states].desc, "FastSleep");
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powernv_states[nr_idle_states].flags = CPUIDLE_FLAG_TIMER_STOP;
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powernv_states[nr_idle_states].target_residency = 300000;
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powernv_states[nr_idle_states].enter = &fastsleep_loop;
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}
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#endif
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powernv_states[nr_idle_states].exit_latency =
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((unsigned int)latency_ns[i]) / 1000;
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if (!rc) {
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powernv_states[nr_idle_states].target_residency =
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((unsigned int)residency_ns[i]) / 1000;
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}
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nr_idle_states++;
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}
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kfree(residency_ns);
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out_free_latency:
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kfree(latency_ns);
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out_free_flags:
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kfree(flags);
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out:
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return nr_idle_states;
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}
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/*
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* powernv_idle_probe()
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* Choose state table for shared versus dedicated partition
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*/
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static int powernv_idle_probe(void)
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{
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if (cpuidle_disable != IDLE_NO_OVERRIDE)
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return -ENODEV;
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if (firmware_has_feature(FW_FEATURE_OPALv3)) {
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cpuidle_state_table = powernv_states;
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/* Device tree can indicate more idle states */
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max_idle_state = powernv_add_idle_states();
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if (max_idle_state > 1) {
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snooze_timeout_en = true;
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snooze_timeout = powernv_states[1].target_residency *
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tb_ticks_per_usec;
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}
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} else
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return -ENODEV;
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return 0;
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}
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static int __init powernv_processor_idle_init(void)
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{
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int retval;
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retval = powernv_idle_probe();
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if (retval)
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return retval;
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powernv_cpuidle_driver_init();
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retval = cpuidle_register(&powernv_idle_driver, NULL);
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if (retval) {
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printk(KERN_DEBUG "Registration of powernv driver failed.\n");
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return retval;
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}
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register_cpu_notifier(&setup_hotplug_notifier);
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printk(KERN_DEBUG "powernv_idle_driver registered\n");
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return 0;
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}
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device_initcall(powernv_processor_idle_init);
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