cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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cpuidle-ux500.c (3099B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Copyright (c) 2012 Linaro : Daniel Lezcano <daniel.lezcano@linaro.org> (IBM)
      4 *
      5 * Based on the work of Rickard Andersson <rickard.andersson@stericsson.com>
      6 * and Jonas Aaberg <jonas.aberg@stericsson.com>.
      7 */
      8
      9#include <linux/init.h>
     10#include <linux/cpuidle.h>
     11#include <linux/spinlock.h>
     12#include <linux/atomic.h>
     13#include <linux/smp.h>
     14#include <linux/mfd/dbx500-prcmu.h>
     15#include <linux/platform_data/arm-ux500-pm.h>
     16#include <linux/platform_device.h>
     17
     18#include <asm/cpuidle.h>
     19
     20static atomic_t master = ATOMIC_INIT(0);
     21static DEFINE_SPINLOCK(master_lock);
     22
     23static inline int ux500_enter_idle(struct cpuidle_device *dev,
     24				   struct cpuidle_driver *drv, int index)
     25{
     26	int this_cpu = smp_processor_id();
     27	bool recouple = false;
     28
     29	if (atomic_inc_return(&master) == num_online_cpus()) {
     30
     31		/* With this lock, we prevent the other cpu to exit and enter
     32		 * this function again and become the master */
     33		if (!spin_trylock(&master_lock))
     34			goto wfi;
     35
     36		/* decouple the gic from the A9 cores */
     37		if (prcmu_gic_decouple()) {
     38			spin_unlock(&master_lock);
     39			goto out;
     40		}
     41
     42		/* If an error occur, we will have to recouple the gic
     43		 * manually */
     44		recouple = true;
     45
     46		/* At this state, as the gic is decoupled, if the other
     47		 * cpu is in WFI, we have the guarantee it won't be wake
     48		 * up, so we can safely go to retention */
     49		if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))
     50			goto out;
     51
     52		/* The prcmu will be in charge of watching the interrupts
     53		 * and wake up the cpus */
     54		if (prcmu_copy_gic_settings())
     55			goto out;
     56
     57		/* Check in the meantime an interrupt did
     58		 * not occur on the gic ... */
     59		if (prcmu_gic_pending_irq())
     60			goto out;
     61
     62		/* ... and the prcmu */
     63		if (prcmu_pending_irq())
     64			goto out;
     65
     66		/* Go to the retention state, the prcmu will wait for the
     67		 * cpu to go WFI and this is what happens after exiting this
     68		 * 'master' critical section */
     69		if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))
     70			goto out;
     71
     72		/* When we switch to retention, the prcmu is in charge
     73		 * of recoupling the gic automatically */
     74		recouple = false;
     75
     76		spin_unlock(&master_lock);
     77	}
     78wfi:
     79	cpu_do_idle();
     80out:
     81	atomic_dec(&master);
     82
     83	if (recouple) {
     84		prcmu_gic_recouple();
     85		spin_unlock(&master_lock);
     86	}
     87
     88	return index;
     89}
     90
     91static struct cpuidle_driver ux500_idle_driver = {
     92	.name = "ux500_idle",
     93	.owner = THIS_MODULE,
     94	.states = {
     95		ARM_CPUIDLE_WFI_STATE,
     96		{
     97			.enter		  = ux500_enter_idle,
     98			.exit_latency	  = 70,
     99			.target_residency = 260,
    100			.flags		  = CPUIDLE_FLAG_TIMER_STOP,
    101			.name		  = "ApIdle",
    102			.desc		  = "ARM Retention",
    103		},
    104	},
    105	.safe_state_index = 0,
    106	.state_count = 2,
    107};
    108
    109static int dbx500_cpuidle_probe(struct platform_device *pdev)
    110{
    111	/* Configure wake up reasons */
    112	prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
    113			     PRCMU_WAKEUP(ABB));
    114
    115	return cpuidle_register(&ux500_idle_driver, NULL);
    116}
    117
    118static struct platform_driver dbx500_cpuidle_plat_driver = {
    119	.driver = {
    120		.name = "db8500-cpuidle",
    121	},
    122	.probe = dbx500_cpuidle_probe,
    123};
    124builtin_platform_driver(dbx500_cpuidle_plat_driver);