diff options
Diffstat (limited to 'drivers/cpuidle/cpuidle-arm.c')
| -rw-r--r-- | drivers/cpuidle/cpuidle-arm.c | 163 |
1 files changed, 163 insertions, 0 deletions
diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c new file mode 100644 index 000000000000..545069d5fdfb --- /dev/null +++ b/drivers/cpuidle/cpuidle-arm.c @@ -0,0 +1,163 @@ +/* + * ARM/ARM64 generic CPU idle driver. + * + * Copyright (C) 2014 ARM Ltd. + * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#define pr_fmt(fmt) "CPUidle arm: " fmt + +#include <linux/cpuidle.h> +#include <linux/cpumask.h> +#include <linux/cpu_pm.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/slab.h> + +#include <asm/cpuidle.h> + +#include "dt_idle_states.h" + +/* + * arm_enter_idle_state - Programs CPU to enter the specified state + * + * dev: cpuidle device + * drv: cpuidle driver + * idx: state index + * + * Called from the CPUidle framework to program the device to the + * specified target state selected by the governor. + */ +static int arm_enter_idle_state(struct cpuidle_device *dev, + struct cpuidle_driver *drv, int idx) +{ + int ret; + + if (!idx) { + cpu_do_idle(); + return idx; + } + + ret = cpu_pm_enter(); + if (!ret) { + /* + * Pass idle state index to cpu_suspend which in turn will + * call the CPU ops suspend protocol with idle index as a + * parameter. + */ + arm_cpuidle_suspend(idx); + + cpu_pm_exit(); + } + + return ret ? -1 : idx; +} + +static struct cpuidle_driver arm_idle_driver = { + .name = "arm_idle", + .owner = THIS_MODULE, + /* + * State at index 0 is standby wfi and considered standard + * on all ARM platforms. If in some platforms simple wfi + * can't be used as "state 0", DT bindings must be implemented + * to work around this issue and allow installing a special + * handler for idle state index 0. + */ + .states[0] = { + .enter = arm_enter_idle_state, + .exit_latency = 1, + .target_residency = 1, + .power_usage = UINT_MAX, + .name = "WFI", + .desc = "ARM WFI", + } +}; + +static const struct of_device_id arm_idle_state_match[] __initconst = { + { .compatible = "arm,idle-state", + .data = arm_enter_idle_state }, + { }, +}; + +/* + * arm_idle_init + * + * Registers the arm specific cpuidle driver with the cpuidle + * framework. It relies on core code to parse the idle states + * and initialize them using driver data structures accordingly. + */ +static int __init arm_idle_init(void) +{ + int cpu, ret; + struct cpuidle_driver *drv = &arm_idle_driver; + struct cpuidle_device *dev; + + /* + * Initialize idle states data, starting at index 1. + * This driver is DT only, if no DT idle states are detected (ret == 0) + * let the driver initialization fail accordingly since there is no + * reason to initialize the idle driver if only wfi is supported. + */ + ret = dt_init_idle_driver(drv, arm_idle_state_match, 1); + if (ret <= 0) + return ret ? : -ENODEV; + + ret = cpuidle_register_driver(drv); + if (ret) { + pr_err("Failed to register cpuidle driver\n"); + return ret; + } + + /* + * Call arch CPU operations in order to initialize + * idle states suspend back-end specific data + */ + for_each_possible_cpu(cpu) { + ret = arm_cpuidle_init(cpu); + + /* + * Skip the cpuidle device initialization if the reported + * failure is a HW misconfiguration/breakage (-ENXIO). + */ + if (ret == -ENXIO) + continue; + + if (ret) { + pr_err("CPU %d failed to init idle CPU ops\n", cpu); + goto out_fail; + } + + dev = kzalloc(sizeof(*dev), GFP_KERNEL); + if (!dev) { + pr_err("Failed to allocate cpuidle device\n"); + goto out_fail; + } + dev->cpu = cpu; + + ret = cpuidle_register_device(dev); + if (ret) { + pr_err("Failed to register cpuidle device for CPU %d\n", + cpu); + kfree(dev); + goto out_fail; + } + } + + return 0; +out_fail: + while (--cpu >= 0) { + dev = per_cpu(cpuidle_devices, cpu); + cpuidle_unregister_device(dev); + kfree(dev); + } + + cpuidle_unregister_driver(drv); + + return ret; +} +device_initcall(arm_idle_init); |