linux/arch/arm/mach-omap2/omap-smp.c
Santosh Shilimkar e97ca477e9 ARM: OMAP4: PM: CPU1 wakeup workaround from Low power modes
The SGI(Software Generated Interrupts) are not wakeup capable from
low power states. This is known limitation on OMAP4 and needs to be
worked around by using software forced clockdomain wake-up. CPU0 forces
the CPU1 clockdomain to software force wakeup.

More details can be found in OMAP4430 TRM - Version J
Section :
	4.3.4.2 Power States of CPU0 and CPU1

Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Jean Pihet <j-pihet@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Tested-by: Vishwanath BS <vishwanath.bs@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>
2011-12-08 11:29:00 -08:00

182 lines
4.6 KiB
C

/*
* OMAP4 SMP source file. It contains platform specific fucntions
* needed for the linux smp kernel.
*
* Copyright (C) 2009 Texas Instruments, Inc.
*
* Author:
* Santosh Shilimkar <santosh.shilimkar@ti.com>
*
* Platform file needed for the OMAP4 SMP. This file is based on arm
* realview smp platform.
* * Copyright (c) 2002 ARM Limited.
*
* 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.
*/
#include <linux/init.h>
#include <linux/device.h>
#include <linux/smp.h>
#include <linux/io.h>
#include <asm/cacheflush.h>
#include <asm/hardware/gic.h>
#include <asm/smp_scu.h>
#include <mach/hardware.h>
#include <mach/omap-secure.h>
#include "common.h"
#include "clockdomain.h"
/* SCU base address */
static void __iomem *scu_base;
static DEFINE_SPINLOCK(boot_lock);
void __iomem *omap4_get_scu_base(void)
{
return scu_base;
}
void __cpuinit platform_secondary_init(unsigned int cpu)
{
/*
* Configure ACTRL and enable NS SMP bit access on CPU1 on HS device.
* OMAP44XX EMU/HS devices - CPU0 SMP bit access is enabled in PPA
* init and for CPU1, a secure PPA API provided. CPU0 must be ON
* while executing NS_SMP API on CPU1 and PPA version must be 1.4.0+.
* OMAP443X GP devices- SMP bit isn't accessible.
* OMAP446X GP devices - SMP bit access is enabled on both CPUs.
*/
if (cpu_is_omap443x() && (omap_type() != OMAP2_DEVICE_TYPE_GP))
omap_secure_dispatcher(OMAP4_PPA_CPU_ACTRL_SMP_INDEX,
4, 0, 0, 0, 0, 0);
/*
* If any interrupts are already enabled for the primary
* core (e.g. timer irq), then they will not have been enabled
* for us: do so
*/
gic_secondary_init(0);
/*
* Synchronise with the boot thread.
*/
spin_lock(&boot_lock);
spin_unlock(&boot_lock);
}
int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
{
static struct clockdomain *cpu1_clkdm;
static bool booted;
/*
* Set synchronisation state between this boot processor
* and the secondary one
*/
spin_lock(&boot_lock);
/*
* Update the AuxCoreBoot0 with boot state for secondary core.
* omap_secondary_startup() routine will hold the secondary core till
* the AuxCoreBoot1 register is updated with cpu state
* A barrier is added to ensure that write buffer is drained
*/
omap_modify_auxcoreboot0(0x200, 0xfffffdff);
flush_cache_all();
smp_wmb();
if (!cpu1_clkdm)
cpu1_clkdm = clkdm_lookup("mpu1_clkdm");
/*
* The SGI(Software Generated Interrupts) are not wakeup capable
* from low power states. This is known limitation on OMAP4 and
* needs to be worked around by using software forced clockdomain
* wake-up. To wakeup CPU1, CPU0 forces the CPU1 clockdomain to
* software force wakeup. The clockdomain is then put back to
* hardware supervised mode.
* More details can be found in OMAP4430 TRM - Version J
* Section :
* 4.3.4.2 Power States of CPU0 and CPU1
*/
if (booted) {
clkdm_wakeup(cpu1_clkdm);
clkdm_allow_idle(cpu1_clkdm);
} else {
dsb_sev();
booted = true;
}
gic_raise_softirq(cpumask_of(cpu), 1);
/*
* Now the secondary core is starting up let it run its
* calibrations, then wait for it to finish
*/
spin_unlock(&boot_lock);
return 0;
}
static void __init wakeup_secondary(void)
{
/*
* Write the address of secondary startup routine into the
* AuxCoreBoot1 where ROM code will jump and start executing
* on secondary core once out of WFE
* A barrier is added to ensure that write buffer is drained
*/
omap_auxcoreboot_addr(virt_to_phys(omap_secondary_startup));
smp_wmb();
/*
* Send a 'sev' to wake the secondary core from WFE.
* Drain the outstanding writes to memory
*/
dsb_sev();
mb();
}
/*
* Initialise the CPU possible map early - this describes the CPUs
* which may be present or become present in the system.
*/
void __init smp_init_cpus(void)
{
unsigned int i, ncores;
/*
* Currently we can't call ioremap here because
* SoC detection won't work until after init_early.
*/
scu_base = OMAP2_L4_IO_ADDRESS(OMAP44XX_SCU_BASE);
BUG_ON(!scu_base);
ncores = scu_get_core_count(scu_base);
/* sanity check */
if (ncores > nr_cpu_ids) {
pr_warn("SMP: %u cores greater than maximum (%u), clipping\n",
ncores, nr_cpu_ids);
ncores = nr_cpu_ids;
}
for (i = 0; i < ncores; i++)
set_cpu_possible(i, true);
set_smp_cross_call(gic_raise_softirq);
}
void __init platform_smp_prepare_cpus(unsigned int max_cpus)
{
/*
* Initialise the SCU and wake up the secondary core using
* wakeup_secondary().
*/
scu_enable(scu_base);
wakeup_secondary();
}