linux-stable/arch/arm/common/krait-l2-accessors.c
Stephen Boyd 36d68f64c4 ARM: Add Krait L2 register accessor functions
Krait CPUs have a handful of L2 cache controller registers that
live behind a cp15 based indirection register. First you program
the indirection register (l2cpselr) to point the L2 'window'
register (l2cpdr) at what you want to read/write.  Then you
read/write the 'window' register to do what you want. The
l2cpselr register is not banked per-cpu so we must lock around
accesses to it to prevent other CPUs from re-pointing l2cpdr
underneath us.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Russell King <linux@arm.linux.org.uk>
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Sricharan R <sricharan@codeaurora.org>
Tested-by: Craig Tatlor <ctatlor97@gmail.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
2018-10-17 13:14:33 -07:00

48 lines
1.2 KiB
C

// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2018, The Linux Foundation. All rights reserved.
#include <linux/spinlock.h>
#include <linux/export.h>
#include <asm/barrier.h>
#include <asm/krait-l2-accessors.h>
static DEFINE_RAW_SPINLOCK(krait_l2_lock);
void krait_set_l2_indirect_reg(u32 addr, u32 val)
{
unsigned long flags;
raw_spin_lock_irqsave(&krait_l2_lock, flags);
/*
* Select the L2 window by poking l2cpselr, then write to the window
* via l2cpdr.
*/
asm volatile ("mcr p15, 3, %0, c15, c0, 6 @ l2cpselr" : : "r" (addr));
isb();
asm volatile ("mcr p15, 3, %0, c15, c0, 7 @ l2cpdr" : : "r" (val));
isb();
raw_spin_unlock_irqrestore(&krait_l2_lock, flags);
}
EXPORT_SYMBOL(krait_set_l2_indirect_reg);
u32 krait_get_l2_indirect_reg(u32 addr)
{
u32 val;
unsigned long flags;
raw_spin_lock_irqsave(&krait_l2_lock, flags);
/*
* Select the L2 window by poking l2cpselr, then read from the window
* via l2cpdr.
*/
asm volatile ("mcr p15, 3, %0, c15, c0, 6 @ l2cpselr" : : "r" (addr));
isb();
asm volatile ("mrc p15, 3, %0, c15, c0, 7 @ l2cpdr" : "=r" (val));
raw_spin_unlock_irqrestore(&krait_l2_lock, flags);
return val;
}
EXPORT_SYMBOL(krait_get_l2_indirect_reg);