linux/arch/mips/kernel/mips-cpc.c

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/*
* Copyright (C) 2013 Imagination Technologies
* Author: Paul Burton <paul.burton@imgtec.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*/
#include <linux/errno.h>
MIPS: smp-cps: rework core/VPE initialisation When hotplug and/or a powered down idle state are supported cases will arise where a non-zero VPE must be brought online without VPE 0, and it where multiple VPEs must be onlined simultaneously. This patch prepares for that by: - Splitting struct boot_config into core & VPE boot config structures, allocated one per core or VPE respectively. This allows for multiple VPEs to be onlined simultaneously without clobbering each others configuration. - Indicating which VPEs should be online within a core at any given time using a bitmap. This allows multiple VPEs to be brought online simultaneously and also indicates to VPE 0 whether it should halt after starting any non-zero VPEs that should be online within the core. For example if all VPEs within a core are offlined via hotplug and the user onlines the second VPE within that core: 1) The core will be powered up. 2) VPE 0 will run from the BEV (ie. mips_cps_core_entry) to initialise the core. 3) VPE 0 will start VPE 1 because its bit is set in the cores bitmap. 4) VPE 0 will halt itself because its bit is clear in the cores bitmap. - Moving the core & VPE initialisation to assembly code which does not make any use of the stack. This is because if a non-zero VPE is to be brought online in a powered down core then when VPE 0 of that core runs it may not have a valid stack, and even if it did then it's messy to run through parts of generic kernel code on VPE 0 before starting the correct VPE. Signed-off-by: Paul Burton <paul.burton@imgtec.com>
2014-04-14 11:04:27 +00:00
#include <linux/percpu.h>
#include <linux/spinlock.h>
#include <asm/mips-cm.h>
#include <asm/mips-cpc.h>
void __iomem *mips_cpc_base;
static DEFINE_PER_CPU_ALIGNED(spinlock_t, cpc_core_lock);
static DEFINE_PER_CPU_ALIGNED(unsigned long, cpc_core_lock_flags);
/**
* mips_cpc_phys_base - retrieve the physical base address of the CPC
*
* This function returns the physical base address of the Cluster Power
* Controller memory mapped registers, or 0 if no Cluster Power Controller
* is present.
*/
static phys_addr_t mips_cpc_phys_base(void)
{
unsigned long cpc_base;
if (!mips_cm_present())
return 0;
if (!(read_gcr_cpc_status() & CM_GCR_CPC_STATUS_EX_MSK))
return 0;
/* If the CPC is already enabled, leave it so */
cpc_base = read_gcr_cpc_base();
if (cpc_base & CM_GCR_CPC_BASE_CPCEN_MSK)
return cpc_base & CM_GCR_CPC_BASE_CPCBASE_MSK;
/* Otherwise, give it the default address & enable it */
cpc_base = mips_cpc_default_phys_base();
write_gcr_cpc_base(cpc_base | CM_GCR_CPC_BASE_CPCEN_MSK);
return cpc_base;
}
int mips_cpc_probe(void)
{
phys_addr_t addr;
unsigned cpu;
for_each_possible_cpu(cpu)
spin_lock_init(&per_cpu(cpc_core_lock, cpu));
addr = mips_cpc_phys_base();
if (!addr)
return -ENODEV;
mips_cpc_base = ioremap_nocache(addr, 0x8000);
if (!mips_cpc_base)
return -ENXIO;
return 0;
}
void mips_cpc_lock_other(unsigned int core)
{
unsigned curr_core;
preempt_disable();
curr_core = current_cpu_data.core;
spin_lock_irqsave(&per_cpu(cpc_core_lock, curr_core),
per_cpu(cpc_core_lock_flags, curr_core));
write_cpc_cl_other(core << CPC_Cx_OTHER_CORENUM_SHF);
/*
* Ensure the core-other region reflects the appropriate core &
* VP before any accesses to it occur.
*/
mb();
}
void mips_cpc_unlock_other(void)
{
unsigned curr_core = current_cpu_data.core;
spin_unlock_irqrestore(&per_cpu(cpc_core_lock, curr_core),
per_cpu(cpc_core_lock_flags, curr_core));
preempt_enable();
}