--- /dev/null
+/*
+ * Copyright (C) 2014 Imagination Technologies
+ * Author: Paul Burton <paul.burton@imgtec.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ */
+
+#include <linux/cpu_pm.h>
+#include <linux/cpuidle.h>
+#include <linux/init.h>
+
+#include <asm/idle.h>
+#include <asm/pm-cps.h>
+
+/* Enumeration of the various idle states this driver may enter */
+enum cps_idle_state {
+ STATE_WAIT = 0, /* MIPS wait instruction, coherent */
+ STATE_NC_WAIT, /* MIPS wait instruction, non-coherent */
+ STATE_CLOCK_GATED, /* Core clock gated */
+ STATE_POWER_GATED, /* Core power gated */
+ STATE_COUNT
+};
+
+static int cps_nc_enter(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv, int index)
+{
+ enum cps_pm_state pm_state;
+ int err;
+
+ /*
+ * At least one core must remain powered up & clocked in order for the
+ * system to have any hope of functioning.
+ *
+ * TODO: don't treat core 0 specially, just prevent the final core
+ * TODO: remap interrupt affinity temporarily
+ */
+ if (!cpu_data[dev->cpu].core && (index > STATE_NC_WAIT))
+ index = STATE_NC_WAIT;
+
+ /* Select the appropriate cps_pm_state */
+ switch (index) {
+ case STATE_NC_WAIT:
+ pm_state = CPS_PM_NC_WAIT;
+ break;
+ case STATE_CLOCK_GATED:
+ pm_state = CPS_PM_CLOCK_GATED;
+ break;
+ case STATE_POWER_GATED:
+ pm_state = CPS_PM_POWER_GATED;
+ break;
+ default:
+ BUG();
+ return -EINVAL;
+ }
+
+ /* Notify listeners the CPU is about to power down */
+ if ((pm_state == CPS_PM_POWER_GATED) && cpu_pm_enter())
+ return -EINTR;
+
+ /* Enter that state */
+ err = cps_pm_enter_state(pm_state);
+
+ /* Notify listeners the CPU is back up */
+ if (pm_state == CPS_PM_POWER_GATED)
+ cpu_pm_exit();
+
+ return err ?: index;
+}
+
+static struct cpuidle_driver cps_driver = {
+ .name = "cpc_cpuidle",
+ .owner = THIS_MODULE,
+ .states = {
+ [STATE_WAIT] = MIPS_CPUIDLE_WAIT_STATE,
+ [STATE_NC_WAIT] = {
+ .enter = cps_nc_enter,
+ .exit_latency = 200,
+ .target_residency = 450,
+ .name = "nc-wait",
+ .desc = "non-coherent MIPS wait",
+ },
+ [STATE_CLOCK_GATED] = {
+ .enter = cps_nc_enter,
+ .exit_latency = 300,
+ .target_residency = 700,
+ .flags = CPUIDLE_FLAG_TIMER_STOP,
+ .name = "clock-gated",
+ .desc = "core clock gated",
+ },
+ [STATE_POWER_GATED] = {
+ .enter = cps_nc_enter,
+ .exit_latency = 600,
+ .target_residency = 1000,
+ .flags = CPUIDLE_FLAG_TIMER_STOP,
+ .name = "power-gated",
+ .desc = "core power gated",
+ },
+ },
+ .state_count = STATE_COUNT,
+ .safe_state_index = 0,
+};
+
+static void __init cps_cpuidle_unregister(void)
+{
+ int cpu;
+ struct cpuidle_device *device;
+
+ for_each_possible_cpu(cpu) {
+ device = &per_cpu(cpuidle_dev, cpu);
+ cpuidle_unregister_device(device);
+ }
+
+ cpuidle_unregister_driver(&cps_driver);
+}
+
+static int __init cps_cpuidle_init(void)
+{
+ int err, cpu, core, i;
+ struct cpuidle_device *device;
+
+ /* Detect supported states */
+ if (!cps_pm_support_state(CPS_PM_POWER_GATED))
+ cps_driver.state_count = STATE_CLOCK_GATED + 1;
+ if (!cps_pm_support_state(CPS_PM_CLOCK_GATED))
+ cps_driver.state_count = STATE_NC_WAIT + 1;
+ if (!cps_pm_support_state(CPS_PM_NC_WAIT))
+ cps_driver.state_count = STATE_WAIT + 1;
+
+ /* Inform the user if some states are unavailable */
+ if (cps_driver.state_count < STATE_COUNT) {
+ pr_info("cpuidle-cps: limited to ");
+ switch (cps_driver.state_count - 1) {
+ case STATE_WAIT:
+ pr_cont("coherent wait\n");
+ break;
+ case STATE_NC_WAIT:
+ pr_cont("non-coherent wait\n");
+ break;
+ case STATE_CLOCK_GATED:
+ pr_cont("clock gating\n");
+ break;
+ }
+ }
+
+ /*
+ * Set the coupled flag on the appropriate states if this system
+ * requires it.
+ */
+ if (coupled_coherence)
+ for (i = STATE_NC_WAIT; i < cps_driver.state_count; i++)
+ cps_driver.states[i].flags |= CPUIDLE_FLAG_COUPLED;
+
+ err = cpuidle_register_driver(&cps_driver);
+ if (err) {
+ pr_err("Failed to register CPS cpuidle driver\n");
+ return err;
+ }
+
+ for_each_possible_cpu(cpu) {
+ core = cpu_data[cpu].core;
+ device = &per_cpu(cpuidle_dev, cpu);
+ device->cpu = cpu;
+#ifdef CONFIG_MIPS_MT
+ cpumask_copy(&device->coupled_cpus, &cpu_sibling_map[cpu]);
+#endif
+
+ err = cpuidle_register_device(device);
+ if (err) {
+ pr_err("Failed to register CPU%d cpuidle device\n",
+ cpu);
+ goto err_out;
+ }
+ }
+
+ return 0;
+err_out:
+ cps_cpuidle_unregister();
+ return err;
+}
+device_initcall(cps_cpuidle_init);
Code Review / kvmfornfv.git / blobdiff