1 files changed, 403 insertions, 0 deletions

diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c
new file mode 100644
index 000000000..c32c600b3
--- /dev/null
+++ b/drivers/cpuidle/cpuidle-powernv.c
@@ -0,0 +1,403 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  cpuidle-powernv - idle state cpuidle driver.
+ *  Adapted from drivers/cpuidle/cpuidle-pseries
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/moduleparam.h>
+#include <linux/cpuidle.h>
+#include <linux/cpu.h>
+#include <linux/notifier.h>
+#include <linux/clockchips.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+
+#include <asm/machdep.h>
+#include <asm/firmware.h>
+#include <asm/opal.h>
+#include <asm/runlatch.h>
+#include <asm/cpuidle.h>
+
+/*
+ * Expose only those Hardware idle states via the cpuidle framework
+ * that have latency value below POWERNV_THRESHOLD_LATENCY_NS.
+ */
+#define POWERNV_THRESHOLD_LATENCY_NS 200000
+
+static struct cpuidle_driver powernv_idle_driver = {
+	.name             = "powernv_idle",
+	.owner            = THIS_MODULE,
+};
+
+static int max_idle_state __read_mostly;
+static struct cpuidle_state *cpuidle_state_table __read_mostly;
+
+struct stop_psscr_table {
+	u64 val;
+	u64 mask;
+};
+
+static struct stop_psscr_table stop_psscr_table[CPUIDLE_STATE_MAX] __read_mostly;
+
+static u64 default_snooze_timeout __read_mostly;
+static bool snooze_timeout_en __read_mostly;
+
+static u64 get_snooze_timeout(struct cpuidle_device *dev,
+			      struct cpuidle_driver *drv,
+			      int index)
+{
+	int i;
+
+	if (unlikely(!snooze_timeout_en))
+		return default_snooze_timeout;
+
+	for (i = index + 1; i < drv->state_count; i++) {
+		if (dev->states_usage[i].disable)
+			continue;
+
+		return drv->states[i].target_residency * tb_ticks_per_usec;
+	}
+
+	return default_snooze_timeout;
+}
+
+static int snooze_loop(struct cpuidle_device *dev,
+			struct cpuidle_driver *drv,
+			int index)
+{
+	u64 snooze_exit_time;
+
+	set_thread_flag(TIF_POLLING_NRFLAG);
+
+	local_irq_enable();
+
+	snooze_exit_time = get_tb() + get_snooze_timeout(dev, drv, index);
+	ppc64_runlatch_off();
+	HMT_very_low();
+	while (!need_resched()) {
+		if (likely(snooze_timeout_en) && get_tb() > snooze_exit_time) {
+			/*
+			 * Task has not woken up but we are exiting the polling
+			 * loop anyway. Require a barrier after polling is
+			 * cleared to order subsequent test of need_resched().
+			 */
+			clear_thread_flag(TIF_POLLING_NRFLAG);
+			smp_mb();
+			break;
+		}
+	}
+
+	HMT_medium();
+	ppc64_runlatch_on();
+	clear_thread_flag(TIF_POLLING_NRFLAG);
+
+	local_irq_disable();
+
+	return index;
+}
+
+static int nap_loop(struct cpuidle_device *dev,
+			struct cpuidle_driver *drv,
+			int index)
+{
+	power7_idle_type(PNV_THREAD_NAP);
+
+	return index;
+}
+
+/* Register for fastsleep only in oneshot mode of broadcast */
+#ifdef CONFIG_TICK_ONESHOT
+static int fastsleep_loop(struct cpuidle_device *dev,
+				struct cpuidle_driver *drv,
+				int index)
+{
+	unsigned long old_lpcr = mfspr(SPRN_LPCR);
+	unsigned long new_lpcr;
+
+	if (unlikely(system_state < SYSTEM_RUNNING))
+		return index;
+
+	new_lpcr = old_lpcr;
+	/* Do not exit powersave upon decrementer as we've setup the timer
+	 * offload.
+	 */
+	new_lpcr &= ~LPCR_PECE1;
+
+	mtspr(SPRN_LPCR, new_lpcr);
+
+	power7_idle_type(PNV_THREAD_SLEEP);
+
+	mtspr(SPRN_LPCR, old_lpcr);
+
+	return index;
+}
+#endif
+
+static int stop_loop(struct cpuidle_device *dev,
+		     struct cpuidle_driver *drv,
+		     int index)
+{
+	arch300_idle_type(stop_psscr_table[index].val,
+			 stop_psscr_table[index].mask);
+	return index;
+}
+
+/*
+ * States for dedicated partition case.
+ */
+static struct cpuidle_state powernv_states[CPUIDLE_STATE_MAX] = {
+	{ /* Snooze */
+		.name = "snooze",
+		.desc = "snooze",
+		.exit_latency = 0,
+		.target_residency = 0,
+		.enter = snooze_loop },
+};
+
+static int powernv_cpuidle_cpu_online(unsigned int cpu)
+{
+	struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
+
+	if (dev && cpuidle_get_driver()) {
+		cpuidle_pause_and_lock();
+		cpuidle_enable_device(dev);
+		cpuidle_resume_and_unlock();
+	}
+	return 0;
+}
+
+static int powernv_cpuidle_cpu_dead(unsigned int cpu)
+{
+	struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
+
+	if (dev && cpuidle_get_driver()) {
+		cpuidle_pause_and_lock();
+		cpuidle_disable_device(dev);
+		cpuidle_resume_and_unlock();
+	}
+	return 0;
+}
+
+/*
+ * powernv_cpuidle_driver_init()
+ */
+static int powernv_cpuidle_driver_init(void)
+{
+	int idle_state;
+	struct cpuidle_driver *drv = &powernv_idle_driver;
+
+	drv->state_count = 0;
+
+	for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
+		/* Is the state not enabled? */
+		if (cpuidle_state_table[idle_state].enter == NULL)
+			continue;
+
+		drv->states[drv->state_count] =	/* structure copy */
+			cpuidle_state_table[idle_state];
+
+		drv->state_count += 1;
+	}
+
+	/*
+	 * On the PowerNV platform cpu_present may be less than cpu_possible in
+	 * cases when firmware detects the CPU, but it is not available to the
+	 * OS.  If CONFIG_HOTPLUG_CPU=n, then such CPUs are not hotplugable at
+	 * run time and hence cpu_devices are not created for those CPUs by the
+	 * generic topology_init().
+	 *
+	 * drv->cpumask defaults to cpu_possible_mask in
+	 * __cpuidle_driver_init().  This breaks cpuidle on PowerNV where
+	 * cpu_devices are not created for CPUs in cpu_possible_mask that
+	 * cannot be hot-added later at run time.
+	 *
+	 * Trying cpuidle_register_device() on a CPU without a cpu_device is
+	 * incorrect, so pass a correct CPU mask to the generic cpuidle driver.
+	 */
+
+	drv->cpumask = (struct cpumask *)cpu_present_mask;
+
+	return 0;
+}
+
+static inline void add_powernv_state(int index, const char *name,
+				     unsigned int flags,
+				     int (*idle_fn)(struct cpuidle_device *,
+						    struct cpuidle_driver *,
+						    int),
+				     unsigned int target_residency,
+				     unsigned int exit_latency,
+				     u64 psscr_val, u64 psscr_mask)
+{
+	strlcpy(powernv_states[index].name, name, CPUIDLE_NAME_LEN);
+	strlcpy(powernv_states[index].desc, name, CPUIDLE_NAME_LEN);
+	powernv_states[index].flags = flags;
+	powernv_states[index].target_residency = target_residency;
+	powernv_states[index].exit_latency = exit_latency;
+	powernv_states[index].enter = idle_fn;
+	/* For power8 and below psscr_* will be 0 */
+	stop_psscr_table[index].val = psscr_val;
+	stop_psscr_table[index].mask = psscr_mask;
+}
+
+extern u32 pnv_get_supported_cpuidle_states(void);
+static int powernv_add_idle_states(void)
+{
+	int nr_idle_states = 1; /* Snooze */
+	int dt_idle_states;
+	u32 has_stop_states = 0;
+	int i;
+	u32 supported_flags = pnv_get_supported_cpuidle_states();
+
+
+	/* Currently we have snooze statically defined */
+	if (nr_pnv_idle_states <= 0) {
+		pr_warn("cpuidle-powernv : Only Snooze is available\n");
+		goto out;
+	}
+
+	/* TODO: Count only states which are eligible for cpuidle */
+	dt_idle_states = nr_pnv_idle_states;
+
+	/*
+	 * Since snooze is used as first idle state, max idle states allowed is
+	 * CPUIDLE_STATE_MAX -1
+	 */
+	if (nr_pnv_idle_states > CPUIDLE_STATE_MAX - 1) {
+		pr_warn("cpuidle-powernv: discovered idle states more than allowed");
+		dt_idle_states = CPUIDLE_STATE_MAX - 1;
+	}
+
+	/*
+	 * If the idle states use stop instruction, probe for psscr values
+	 * and psscr mask which are necessary to specify required stop level.
+	 */
+	has_stop_states = (pnv_idle_states[0].flags &
+			   (OPAL_PM_STOP_INST_FAST | OPAL_PM_STOP_INST_DEEP));
+
+	for (i = 0; i < dt_idle_states; i++) {
+		unsigned int exit_latency, target_residency;
+		bool stops_timebase = false;
+		struct pnv_idle_states_t *state = &pnv_idle_states[i];
+
+		/*
+		 * Skip the platform idle state whose flag isn't in
+		 * the supported_cpuidle_states flag mask.
+		 */
+		if ((state->flags & supported_flags) != state->flags)
+			continue;
+		/*
+		 * If an idle state has exit latency beyond
+		 * POWERNV_THRESHOLD_LATENCY_NS then don't use it
+		 * in cpu-idle.
+		 */
+		if (state->latency_ns > POWERNV_THRESHOLD_LATENCY_NS)
+			continue;
+		/*
+		 * Firmware passes residency and latency values in ns.
+		 * cpuidle expects it in us.
+		 */
+		exit_latency = DIV_ROUND_UP(state->latency_ns, 1000);
+		target_residency = DIV_ROUND_UP(state->residency_ns, 1000);
+
+		if (has_stop_states && !(state->valid))
+				continue;
+
+		if (state->flags & OPAL_PM_TIMEBASE_STOP)
+			stops_timebase = true;
+
+		if (state->flags & OPAL_PM_NAP_ENABLED) {
+			/* Add NAP state */
+			add_powernv_state(nr_idle_states, "Nap",
+					  CPUIDLE_FLAG_NONE, nap_loop,
+					  target_residency, exit_latency, 0, 0);
+		} else if (has_stop_states && !stops_timebase) {
+			add_powernv_state(nr_idle_states, state->name,
+					  CPUIDLE_FLAG_NONE, stop_loop,
+					  target_residency, exit_latency,
+					  state->psscr_val,
+					  state->psscr_mask);
+		}
+
+		/*
+		 * All cpuidle states with CPUIDLE_FLAG_TIMER_STOP set must come
+		 * within this config dependency check.
+		 */
+#ifdef CONFIG_TICK_ONESHOT
+		else if (state->flags & OPAL_PM_SLEEP_ENABLED ||
+			 state->flags & OPAL_PM_SLEEP_ENABLED_ER1) {
+			/* Add FASTSLEEP state */
+			add_powernv_state(nr_idle_states, "FastSleep",
+					  CPUIDLE_FLAG_TIMER_STOP,
+					  fastsleep_loop,
+					  target_residency, exit_latency, 0, 0);
+		} else if (has_stop_states && stops_timebase) {
+			add_powernv_state(nr_idle_states, state->name,
+					  CPUIDLE_FLAG_TIMER_STOP, stop_loop,
+					  target_residency, exit_latency,
+					  state->psscr_val,
+					  state->psscr_mask);
+		}
+#endif
+		else
+			continue;
+		nr_idle_states++;
+	}
+out:
+	return nr_idle_states;
+}
+
+/*
+ * powernv_idle_probe()
+ * Choose state table for shared versus dedicated partition
+ */
+static int powernv_idle_probe(void)
+{
+	if (cpuidle_disable != IDLE_NO_OVERRIDE)
+		return -ENODEV;
+
+	if (firmware_has_feature(FW_FEATURE_OPAL)) {
+		cpuidle_state_table = powernv_states;
+		/* Device tree can indicate more idle states */
+		max_idle_state = powernv_add_idle_states();
+		default_snooze_timeout = TICK_USEC * tb_ticks_per_usec;
+		if (max_idle_state > 1)
+			snooze_timeout_en = true;
+ 	} else
+ 		return -ENODEV;
+
+	return 0;
+}
+
+static int __init powernv_processor_idle_init(void)
+{
+	int retval;
+
+	retval = powernv_idle_probe();
+	if (retval)
+		return retval;
+
+	powernv_cpuidle_driver_init();
+	retval = cpuidle_register(&powernv_idle_driver, NULL);
+	if (retval) {
+		printk(KERN_DEBUG "Registration of powernv driver failed.\n");
+		return retval;
+	}
+
+	retval = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
+					   "cpuidle/powernv:online",
+					   powernv_cpuidle_cpu_online, NULL);
+	WARN_ON(retval < 0);
+	retval = cpuhp_setup_state_nocalls(CPUHP_CPUIDLE_DEAD,
+					   "cpuidle/powernv:dead", NULL,
+					   powernv_cpuidle_cpu_dead);
+	WARN_ON(retval < 0);
+	printk(KERN_DEBUG "powernv_idle_driver registered\n");
+	return 0;
+}
+
+device_initcall(powernv_processor_idle_init);