// SPDX-License-Identifier: GPL-2.0-only

  /*
   * Copyright (c) 2013 ARM/Linaro
   *
   * Authors: Daniel Lezcano <daniel.lezcano@linaro.org>
   *          Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
   *          Nicolas Pitre <nicolas.pitre@linaro.org>
   *

   * Maintainer: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
   * Maintainer: Daniel Lezcano <daniel.lezcano@linaro.org>
   */
  #include <linux/cpuidle.h>
  #include <linux/cpu_pm.h>
  #include <linux/slab.h>
  #include <linux/of.h>
  
  #include <asm/cpu.h>
  #include <asm/cputype.h>
  #include <asm/cpuidle.h>
  #include <asm/mcpm.h>
  #include <asm/smp_plat.h>
  #include <asm/suspend.h>

  #include "dt_idle_states.h"

  static int bl_enter_powerdown(struct cpuidle_device *dev,
  			      struct cpuidle_driver *drv, int idx);
  
  /*
   * NB: Owing to current menu governor behaviour big and LITTLE
   * index 1 states have to define exit_latency and target_residency for
   * cluster state since, when all CPUs in a cluster hit it, the cluster
   * can be shutdown. This means that when a single CPU enters this state
   * the exit_latency and target_residency values are somewhat overkill.
   * There is no notion of cluster states in the menu governor, so CPUs
   * have to define CPU states where possibly the cluster will be shutdown
   * depending on the state of other CPUs. idle states entry and exit happen
   * at random times; however the cluster state provides target_residency
   * values as if all CPUs in a cluster enter the state at once; this is
   * somewhat optimistic and behaviour should be fixed either in the governor
   * or in the MCPM back-ends.
   * To make this driver 100% generic the number of states and the exit_latency
   * target_residency values must be obtained from device tree bindings.
   *
   * exit_latency: refers to the TC2 vexpress test chip and depends on the
   * current cluster operating point. It is the time it takes to get the CPU
   * up and running when the CPU is powered up on cluster wake-up from shutdown.
   * Current values for big and LITTLE clusters are provided for clusters
   * running at default operating points.
   *
   * target_residency: it is the minimum amount of time the cluster has
   * to be down to break even in terms of power consumption. cluster
   * shutdown has inherent dynamic power costs (L2 writebacks to DRAM
   * being the main factor) that depend on the current operating points.
   * The current values for both clusters are provided for a CPU whose half
   * of L2 lines are dirty and require cleaning to DRAM, and takes into
   * account leakage static power values related to the vexpress TC2 testchip.
   */
  static struct cpuidle_driver bl_idle_little_driver = {
  	.name = "little_idle",
  	.owner = THIS_MODULE,
  	.states[0] = ARM_CPUIDLE_WFI_STATE,
  	.states[1] = {
  		.enter			= bl_enter_powerdown,
  		.exit_latency		= 700,
  		.target_residency	= 2500,

  		.flags			= CPUIDLE_FLAG_TIMER_STOP,

  		.name			= "C1",
  		.desc			= "ARM little-cluster power down",
  	},
  	.state_count = 2,
  };

  static const struct of_device_id bl_idle_state_match[] __initconst = {
  	{ .compatible = "arm,idle-state",
  	  .data = bl_enter_powerdown },
  	{ },
  };

  static struct cpuidle_driver bl_idle_big_driver = {
  	.name = "big_idle",
  	.owner = THIS_MODULE,
  	.states[0] = ARM_CPUIDLE_WFI_STATE,
  	.states[1] = {
  		.enter			= bl_enter_powerdown,
  		.exit_latency		= 500,
  		.target_residency	= 2000,

  		.flags			= CPUIDLE_FLAG_TIMER_STOP,

  		.name			= "C1",
  		.desc			= "ARM big-cluster power down",
  	},
  	.state_count = 2,
  };
  
  /*
   * notrace prevents trace shims from getting inserted where they
   * should not. Global jumps and ldrex/strex must not be inserted
   * in power down sequences where caches and MMU may be turned off.
   */
  static int notrace bl_powerdown_finisher(unsigned long arg)
  {
  	/* MCPM works with HW CPU identifiers */
  	unsigned int mpidr = read_cpuid_mpidr();
  	unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
  	unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
  
  	mcpm_set_entry_vector(cpu, cluster, cpu_resume);

  	mcpm_cpu_suspend();

  
  	/* return value != 0 means failure */
  	return 1;
  }
  
  /**
   * bl_enter_powerdown - Programs CPU to enter the specified state
   * @dev: cpuidle device
   * @drv: The target state to be programmed
   * @idx: state index
   *
   * Called from the CPUidle framework to program the device to the
   * specified target state selected by the governor.
   */
  static int bl_enter_powerdown(struct cpuidle_device *dev,
  				struct cpuidle_driver *drv, int idx)
  {
  	cpu_pm_enter();
  
  	cpu_suspend(0, bl_powerdown_finisher);
  
  	/* signals the MCPM core that CPU is out of low power state */
  	mcpm_cpu_powered_up();
  
  	cpu_pm_exit();
  
  	return idx;
  }

  static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int part_id)

  {

  	struct cpumask *cpumask;

  	int cpu;
  
  	cpumask = kzalloc(cpumask_size(), GFP_KERNEL);
  	if (!cpumask)
  		return -ENOMEM;

  	for_each_possible_cpu(cpu)
  		if (smp_cpuid_part(cpu) == part_id)

  			cpumask_set_cpu(cpu, cpumask);

  
  	drv->cpumask = cpumask;
  
  	return 0;
  }

  static const struct of_device_id compatible_machine_match[] = {
  	{ .compatible = "arm,vexpress,v2p-ca15_a7" },

  	{ .compatible = "samsung,exynos5420" },

  	{ .compatible = "samsung,exynos5800" },

  	{},
  };

  static int __init bl_idle_init(void)
  {
  	int ret;

  	struct device_node *root = of_find_node_by_path("/");

  	const struct of_device_id *match_id;

  
  	if (!root)
  		return -ENODEV;

  
  	/*
  	 * Initialize the driver just for a compliant set of machines
  	 */

  	match_id = of_match_node(compatible_machine_match, root);
  
  	of_node_put(root);
  
  	if (!match_id)

  		return -ENODEV;

  
  	if (!mcpm_is_available())
  		return -EUNATCH;

  	/*
  	 * For now the differentiation between little and big cores
  	 * is based on the part number. A7 cores are considered little
  	 * cores, A15 are considered big cores. This distinction may
  	 * evolve in the future with a more generic matching approach.
  	 */
  	ret = bl_idle_driver_init(&bl_idle_little_driver,
  				  ARM_CPU_PART_CORTEX_A7);
  	if (ret)
  		return ret;
  
  	ret = bl_idle_driver_init(&bl_idle_big_driver, ARM_CPU_PART_CORTEX_A15);
  	if (ret)
  		goto out_uninit_little;

  	/* Start at index 1, index 0 standard WFI */
  	ret = dt_init_idle_driver(&bl_idle_big_driver, bl_idle_state_match, 1);
  	if (ret < 0)
  		goto out_uninit_big;
  
  	/* Start at index 1, index 0 standard WFI */
  	ret = dt_init_idle_driver(&bl_idle_little_driver,
  				  bl_idle_state_match, 1);
  	if (ret < 0)
  		goto out_uninit_big;

  	ret = cpuidle_register(&bl_idle_little_driver, NULL);
  	if (ret)
  		goto out_uninit_big;
  
  	ret = cpuidle_register(&bl_idle_big_driver, NULL);
  	if (ret)
  		goto out_unregister_little;
  
  	return 0;
  
  out_unregister_little:
  	cpuidle_unregister(&bl_idle_little_driver);
  out_uninit_big:
  	kfree(bl_idle_big_driver.cpumask);
  out_uninit_little:
  	kfree(bl_idle_little_driver.cpumask);
  
  	return ret;
  }
  device_initcall(bl_idle_init);