mirror of
https://github.com/torvalds/linux.git
synced 2024-12-23 03:11:46 +00:00
292ec42af7
Add a function to set the SCU low-power mode for SMP CPUs. This centralizes this functionality rather than having to expose the SCU register definitions to each platform. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
76 lines
1.7 KiB
C
76 lines
1.7 KiB
C
/*
|
|
* linux/arch/arm/kernel/smp_scu.c
|
|
*
|
|
* Copyright (C) 2002 ARM Ltd.
|
|
* All Rights Reserved
|
|
*
|
|
* 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/io.h>
|
|
|
|
#include <asm/smp_scu.h>
|
|
#include <asm/cacheflush.h>
|
|
|
|
#define SCU_CTRL 0x00
|
|
#define SCU_CONFIG 0x04
|
|
#define SCU_CPU_STATUS 0x08
|
|
#define SCU_INVALIDATE 0x0c
|
|
#define SCU_FPGA_REVISION 0x10
|
|
|
|
/*
|
|
* Get the number of CPU cores from the SCU configuration
|
|
*/
|
|
unsigned int __init scu_get_core_count(void __iomem *scu_base)
|
|
{
|
|
unsigned int ncores = __raw_readl(scu_base + SCU_CONFIG);
|
|
return (ncores & 0x03) + 1;
|
|
}
|
|
|
|
/*
|
|
* Enable the SCU
|
|
*/
|
|
void __init scu_enable(void __iomem *scu_base)
|
|
{
|
|
u32 scu_ctrl;
|
|
|
|
scu_ctrl = __raw_readl(scu_base + SCU_CTRL);
|
|
/* already enabled? */
|
|
if (scu_ctrl & 1)
|
|
return;
|
|
|
|
scu_ctrl |= 1;
|
|
__raw_writel(scu_ctrl, scu_base + SCU_CTRL);
|
|
|
|
/*
|
|
* Ensure that the data accessed by CPU0 before the SCU was
|
|
* initialised is visible to the other CPUs.
|
|
*/
|
|
flush_cache_all();
|
|
}
|
|
|
|
/*
|
|
* Set the executing CPUs power mode as defined. This will be in
|
|
* preparation for it executing a WFI instruction.
|
|
*
|
|
* This function must be called with preemption disabled, and as it
|
|
* has the side effect of disabling coherency, caches must have been
|
|
* flushed. Interrupts must also have been disabled.
|
|
*/
|
|
int scu_power_mode(void __iomem *scu_base, unsigned int mode)
|
|
{
|
|
unsigned int val;
|
|
int cpu = smp_processor_id();
|
|
|
|
if (mode > 3 || mode == 1 || cpu > 3)
|
|
return -EINVAL;
|
|
|
|
val = __raw_readb(scu_base + SCU_CPU_STATUS + cpu) & ~0x03;
|
|
val |= mode;
|
|
__raw_writeb(val, scu_base + SCU_CPU_STATUS + cpu);
|
|
|
|
return 0;
|
|
}
|