linux/arch/arm/include/asm/arch_timer.h
Sonny Rao 0b46b8a718 clocksource: arch_timer: Fix code to use physical timers when requested
This is a bug fix for using physical arch timers when
the arch_timer_use_virtual boolean is false.  It restores the
arch_counter_get_cntpct() function after removal in

0d651e4e "clocksource: arch_timer: use virtual counters"

We need this on certain ARMv7 systems which are architected like this:

* The firmware doesn't know and doesn't care about hypervisor mode and
  we don't want to add the complexity of hypervisor there.

* The firmware isn't involved in SMP bringup or resume.

* The ARCH timer come up with an uninitialized offset between the
  virtual and physical counters.  Each core gets a different random
  offset.

* The device boots in "Secure SVC" mode.

* Nothing has touched the reset value of CNTHCTL.PL1PCEN or
  CNTHCTL.PL1PCTEN (both default to 1 at reset)

One example of such as system is RK3288 where it is much simpler to
use the physical counter since there's nobody managing the offset and
each time a core goes down and comes back up it will get reinitialized
to some other random value.

Fixes: 0d651e4e65 ("clocksource: arch_timer: use virtual counters")
Cc: stable@vger.kernel.org
Signed-off-by: Sonny Rao <sonnyrao@chromium.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Olof Johansson <olof@lixom.net>
2014-12-04 23:30:26 -08:00

114 lines
2.4 KiB
C

#ifndef __ASMARM_ARCH_TIMER_H
#define __ASMARM_ARCH_TIMER_H
#include <asm/barrier.h>
#include <asm/errno.h>
#include <linux/clocksource.h>
#include <linux/init.h>
#include <linux/types.h>
#include <clocksource/arm_arch_timer.h>
#ifdef CONFIG_ARM_ARCH_TIMER
int arch_timer_arch_init(void);
/*
* These register accessors are marked inline so the compiler can
* nicely work out which register we want, and chuck away the rest of
* the code. At least it does so with a recent GCC (4.6.3).
*/
static __always_inline
void arch_timer_reg_write_cp15(int access, enum arch_timer_reg reg, u32 val)
{
if (access == ARCH_TIMER_PHYS_ACCESS) {
switch (reg) {
case ARCH_TIMER_REG_CTRL:
asm volatile("mcr p15, 0, %0, c14, c2, 1" : : "r" (val));
break;
case ARCH_TIMER_REG_TVAL:
asm volatile("mcr p15, 0, %0, c14, c2, 0" : : "r" (val));
break;
}
} else if (access == ARCH_TIMER_VIRT_ACCESS) {
switch (reg) {
case ARCH_TIMER_REG_CTRL:
asm volatile("mcr p15, 0, %0, c14, c3, 1" : : "r" (val));
break;
case ARCH_TIMER_REG_TVAL:
asm volatile("mcr p15, 0, %0, c14, c3, 0" : : "r" (val));
break;
}
}
isb();
}
static __always_inline
u32 arch_timer_reg_read_cp15(int access, enum arch_timer_reg reg)
{
u32 val = 0;
if (access == ARCH_TIMER_PHYS_ACCESS) {
switch (reg) {
case ARCH_TIMER_REG_CTRL:
asm volatile("mrc p15, 0, %0, c14, c2, 1" : "=r" (val));
break;
case ARCH_TIMER_REG_TVAL:
asm volatile("mrc p15, 0, %0, c14, c2, 0" : "=r" (val));
break;
}
} else if (access == ARCH_TIMER_VIRT_ACCESS) {
switch (reg) {
case ARCH_TIMER_REG_CTRL:
asm volatile("mrc p15, 0, %0, c14, c3, 1" : "=r" (val));
break;
case ARCH_TIMER_REG_TVAL:
asm volatile("mrc p15, 0, %0, c14, c3, 0" : "=r" (val));
break;
}
}
return val;
}
static inline u32 arch_timer_get_cntfrq(void)
{
u32 val;
asm volatile("mrc p15, 0, %0, c14, c0, 0" : "=r" (val));
return val;
}
static inline u64 arch_counter_get_cntpct(void)
{
u64 cval;
isb();
asm volatile("mrrc p15, 0, %Q0, %R0, c14" : "=r" (cval));
return cval;
}
static inline u64 arch_counter_get_cntvct(void)
{
u64 cval;
isb();
asm volatile("mrrc p15, 1, %Q0, %R0, c14" : "=r" (cval));
return cval;
}
static inline u32 arch_timer_get_cntkctl(void)
{
u32 cntkctl;
asm volatile("mrc p15, 0, %0, c14, c1, 0" : "=r" (cntkctl));
return cntkctl;
}
static inline void arch_timer_set_cntkctl(u32 cntkctl)
{
asm volatile("mcr p15, 0, %0, c14, c1, 0" : : "r" (cntkctl));
}
#endif
#endif