diff options
Diffstat (limited to 'drivers/cpuidle/cpuidle-cps.c')
| -rw-r--r-- | drivers/cpuidle/cpuidle-cps.c | 178 |
1 files changed, 178 insertions, 0 deletions
diff --git a/drivers/cpuidle/cpuidle-cps.c b/drivers/cpuidle/cpuidle-cps.c new file mode 100644 index 000000000..dff0ff4cc --- /dev/null +++ b/drivers/cpuidle/cpuidle-cps.c @@ -0,0 +1,178 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2014 Imagination Technologies + * Author: Paul Burton <paul.burton@mips.com> + */ + +#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 (cpus_are_siblings(0, dev->cpu) && (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, 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) { + device = &per_cpu(cpuidle_dev, cpu); + device->cpu = cpu; +#ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED + 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); |