// SPDX-License-Identifier: GPL-2.0-only
/*
 * ARM/ARM64 generic CPU idle driver.
 *
 * Copyright (C) 2014 ARM Ltd.
 * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
 */

#define pr_fmt(fmt) "CPUidle arm: " fmt

#include <linux/cpu_cooling.h>
#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 __cpuidle int arm_enter_idle_state(struct cpuidle_device *dev,
                                          struct cpuidle_driver *drv, int idx)
{
        /*
         * Pass idle state index to arm_cpuidle_suspend which in turn
         * will call the CPU ops suspend protocol with idle index as a
         * parameter.
         */
        return CPU_PM_CPU_IDLE_ENTER(arm_cpuidle_suspend, idx);
}

static struct cpuidle_driver arm_idle_driver __initdata = {
        .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_cpu
 *
 * 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_cpu(int cpu)
{
        int ret;
        struct cpuidle_driver *drv;

        drv = kmemdup(&arm_idle_driver, sizeof(*drv), GFP_KERNEL);
        if (!drv)
                return -ENOMEM;

        drv->cpumask = (struct cpumask *)cpumask_of(cpu);

        /*
         * 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) {
                ret = ret ? : -ENODEV;
                goto out_kfree_drv;
        }

        /*
         * Call arch CPU operations in order to initialize
         * idle states suspend back-end specific data
         */
        ret = arm_cpuidle_init(cpu);

        /*
         * Allow the initialization to continue for other CPUs, if the
         * reported failure is a HW misconfiguration/breakage (-ENXIO).
         *
         * Some platforms do not support idle operations
         * (arm_cpuidle_init() returning -EOPNOTSUPP), we should
         * not flag this case as an error, it is a valid
         * configuration.
         */
        if (ret) {
                if (ret != -EOPNOTSUPP)
                        pr_err("CPU %d failed to init idle CPU ops\n", cpu);
                ret = ret == -ENXIO ? 0 : ret;
                goto out_kfree_drv;
        }

        ret = cpuidle_register(drv, NULL);
        if (ret)
                goto out_kfree_drv;

        cpuidle_cooling_register(drv);

        return 0;

out_kfree_drv:
        kfree(drv);
        return ret;
}

/*
 * arm_idle_init - Initializes arm cpuidle driver
 *
 * Initializes arm cpuidle driver for all present CPUs, if any
 * CPU fails to register cpuidle driver then rollback to cancel
 * all CPUs registration.
 */
static int __init arm_idle_init(void)
{
        int cpu, ret;
        struct cpuidle_driver *drv;
        struct cpuidle_device *dev;

        for_each_present_cpu(cpu) {
                ret = arm_idle_init_cpu(cpu);
                if (ret)
                        goto out_fail;
        }

        return 0;

out_fail:
        while (--cpu >= 0) {
                dev = per_cpu(cpuidle_devices, cpu);
                drv = cpuidle_get_cpu_driver(dev);
                cpuidle_unregister(drv);
                kfree(drv);
        }

        return ret;
}
device_initcall(arm_idle_init);