arm: Move to upstream udelay via timer implementation
This is a squash of a handful of changes and reverts of the
Qualcomm specific implementation:
Revert "arm: Implement a timer based __delay() loop"
This reverts commit 976eafa8b18252876e15f861944acf693b07ce7e.
Revert "arm: Allow machines to override __delay()"
This reverts commit bc0ef8ab167272890f1aab62928b04a9aeb87ce9.
Revert "arm: Translate delay.S into (mostly) C"
This reverts commit 8d5868d8205d10a0a8e423f53e9cc9bb3e9d1a34.
ARM: 7451/1: arch timer: implement read_current_timer and get_cycles
This patch implements read_current_timer using the architected timers
when they are selected via CONFIG_ARM_ARCH_TIMER. If they are detected
not to be usable at runtime, we return -ENXIO to the caller.
Furthermore, if read_current_timer is exported then we can implement
get_cycles in terms of it for use as both an entropy source and for
implementing __udelay and friends.
Tested-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
ARM: 7452/1: delay: allow timer-based delay implementation to be
selected
This patch allows a timer-based delay implementation to be selected by
switching the delay routines over to use get_cycles, which is
implemented in terms of read_current_timer. This further allows us to
skip the loop calibration and have a consistent delay function in the
face of core frequency scaling.
To avoid the pain of dealing with memory-mapped counters, this
implementation uses the co-processor interface to the architected timers
when they are available. The previous loop-based implementation is
kept around for CPUs without the architected timers and we retain both
the maximum delay (2ms) and the corresponding conversion factors for
determining the number of loops required for a given interval. Since the
indirection of the timer routines will only work when called from C,
the sa1100 sleep routines are modified to branch to the loop-based delay
functions directly.
Tested-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
ARM: delay: set loops_per_jiffy when moving to timer-based loop
The delay functions may be called by some platforms between switching to
the timer-based delay loop but before calibration. In this case, the
initial loops_per_jiffy may not be suitable for the timer (although a
compromise may be achievable) and delay times may be considered too
inaccurate.
This patch updates loops_per_jiffy when switching to the timer-based
delay loop so that delays are consistent prior to calibration.
Signed-off-by: Will Deacon <will.deacon@arm.com>
ARM: delay: add registration mechanism for delay timer sources
The current timer-based delay loop relies on the architected timer to
initiate the switch away from the polling-based implementation. This is
unfortunate for platforms without the architected timers but with a
suitable delay source (that is, constant frequency, always powered-up
and ticking as long as the CPUs are online).
This patch introduces a registration mechanism for the delay timer
(which provides an unconditional read_current_timer implementation) and
updates the architected timer code to use the new interface.
Signed-off-by: Jonathan Austin <jonathan.austin@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
ARM: export default read_current_timer
read_current_timer is used by get_cycles since "ARM: 7538/1: delay:
add registration mechanism for delay timer sources", and get_cycles
can be used by device drivers in loadable modules, so it has to
be exported.
Without this patch, building imote2_defconfig fails with
ERROR: "read_current_timer" [crypto/tcrypt.ko] undefined!
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Jonathan Austin <jonathan.austin@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Change-Id: If1ad095d6852f5966ea995856103e06de6ab2f59
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
diff --git a/arch/arm/mach-msm/timer.c b/arch/arm/mach-msm/timer.c
index 212ad77..e3a29ff 100644
--- a/arch/arm/mach-msm/timer.c
+++ b/arch/arm/mach-msm/timer.c
@@ -942,11 +942,12 @@
return cs->read(NULL);
}
-int read_current_timer(unsigned long *timer_val)
+static struct delay_timer msm_delay_timer;
+
+static unsigned long msm_read_current_timer(void)
{
struct msm_clock *dgt = &msm_clocks[MSM_CLOCK_DGT];
- *timer_val = msm_read_timer_count(dgt, GLOBAL_TIMER);
- return 0;
+ return msm_read_timer_count(dgt, GLOBAL_TIMER);
}
static void __init msm_sched_clock_init(void)
@@ -1183,13 +1184,13 @@
}
}
-#ifdef ARCH_HAS_READ_CURRENT_TIMER
if (is_smp()) {
__raw_writel(1,
msm_clocks[MSM_CLOCK_DGT].regbase + TIMER_ENABLE);
- set_delay_fn(read_current_timer_delay_loop);
+ msm_delay_timer.freq = dgt->freq;
+ msm_delay_timer.read_current_timer = &msm_read_current_timer;
+ register_current_timer_delay(&msm_delay_timer);
}
-#endif
#ifdef CONFIG_LOCAL_TIMERS
local_timer_register(&msm_lt_ops);