2010-10-08 19:40:19 +02:00
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/*
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* OMAP 32ksynctimer/counter_32k-related code
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*
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* Copyright (C) 2009 Texas Instruments
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* Copyright (C) 2010 Nokia Corporation
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* Tony Lindgren <tony@atomide.com>
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* Added OMAP4 support - Santosh Shilimkar <santosh.shilimkar@ti.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* NOTE: This timer is not the same timer as the old OMAP1 MPU timer.
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/clk.h>
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2010-11-26 18:06:02 +01:00
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#include <linux/err.h>
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2010-10-08 19:40:19 +02:00
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#include <linux/io.h>
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2011-07-11 08:05:34 +02:00
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#include <linux/clocksource.h>
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2010-10-08 19:40:19 +02:00
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2012-05-05 20:28:44 +02:00
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#include <asm/mach/time.h>
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2010-12-15 22:53:51 +01:00
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#include <asm/sched_clock.h>
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2010-10-08 19:40:19 +02:00
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#include <plat/common.h>
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#include <plat/clock.h>
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ARM: OMAP: Make OMAP clocksource source selection using kernel param
Current OMAP code supports couple of clocksource options based
on compilation flag (CONFIG_OMAP_32K_TIMER). The 32KHz sync-timer
and a gptimer which can run on 32KHz or system clock (e.g 38.4 MHz).
So there can be 3 options -
1. 32KHz sync-timer
2. Sys_clock based (e.g 13/19.2/26/38.4 MHz) gptimer
3. 32KHz based gptimer.
The optional gptimer based clocksource was added so that it can
give the high precision than sync-timer, so expected usage was 2
and not 3.
Unfortunately option 2, clocksource doesn't meet the requirement of
free-running clock as per clocksource need. It stops in low power states
when sys_clock is cut. That makes gptimer based clocksource option
useless for OMAP2/3/4 devices with sys_clock as a clock input.
So, in order to use option 2, deeper idle state MUST be disabled.
Option 3 will still work but it is no better than 32K sync-timer
based clocksource.
We must support both sync timer and gptimer based clocksource as
some OMAP based derivative SoCs like AM33XX does not have the
sync timer.
Considering above, make sync-timer and gptimer clocksource runtime
selectable so that both OMAP and AMXXXX continue to use the same code.
And, in order to precisely configure/setup sched_clock for given
clocksource, decision has to be made early enough in boot sequence.
So, the solution is,
Use standard kernel parameter ("clocksource=") to override
default 32k_sync-timer, in addition to this, we also use hwmod database
lookup mechanism, through which at run-time we can identify availability
of 32k-sync timer on the device, else fall back to gptimer.
Also, moved low-level SoC specific init code to respective files,
(mach-omap1/timer32k.c and mach-omap2/timer.c)
Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tarun Kanti DebBarma <tarun.kanti@ti.com>
Cc: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
2012-05-09 19:07:05 +02:00
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/* OMAP2_32KSYNCNT_CR_OFF: offset of 32ksync counter register */
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2012-05-10 10:47:22 +02:00
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#define OMAP2_32KSYNCNT_REV_OFF 0x0
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#define OMAP2_32KSYNCNT_REV_SCHEME (0x3 << 30)
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#define OMAP2_32KSYNCNT_CR_OFF_LOW 0x10
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#define OMAP2_32KSYNCNT_CR_OFF_HIGH 0x30
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ARM: OMAP: Make OMAP clocksource source selection using kernel param
Current OMAP code supports couple of clocksource options based
on compilation flag (CONFIG_OMAP_32K_TIMER). The 32KHz sync-timer
and a gptimer which can run on 32KHz or system clock (e.g 38.4 MHz).
So there can be 3 options -
1. 32KHz sync-timer
2. Sys_clock based (e.g 13/19.2/26/38.4 MHz) gptimer
3. 32KHz based gptimer.
The optional gptimer based clocksource was added so that it can
give the high precision than sync-timer, so expected usage was 2
and not 3.
Unfortunately option 2, clocksource doesn't meet the requirement of
free-running clock as per clocksource need. It stops in low power states
when sys_clock is cut. That makes gptimer based clocksource option
useless for OMAP2/3/4 devices with sys_clock as a clock input.
So, in order to use option 2, deeper idle state MUST be disabled.
Option 3 will still work but it is no better than 32K sync-timer
based clocksource.
We must support both sync timer and gptimer based clocksource as
some OMAP based derivative SoCs like AM33XX does not have the
sync timer.
Considering above, make sync-timer and gptimer clocksource runtime
selectable so that both OMAP and AMXXXX continue to use the same code.
And, in order to precisely configure/setup sched_clock for given
clocksource, decision has to be made early enough in boot sequence.
So, the solution is,
Use standard kernel parameter ("clocksource=") to override
default 32k_sync-timer, in addition to this, we also use hwmod database
lookup mechanism, through which at run-time we can identify availability
of 32k-sync timer on the device, else fall back to gptimer.
Also, moved low-level SoC specific init code to respective files,
(mach-omap1/timer32k.c and mach-omap2/timer.c)
Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tarun Kanti DebBarma <tarun.kanti@ti.com>
Cc: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
2012-05-09 19:07:05 +02:00
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2010-10-08 19:40:19 +02:00
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/*
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* 32KHz clocksource ... always available, on pretty most chips except
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* OMAP 730 and 1510. Other timers could be used as clocksources, with
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* higher resolution in free-running counter modes (e.g. 12 MHz xtal),
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* but systems won't necessarily want to spend resources that way.
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*/
|
ARM: OMAP: Make OMAP clocksource source selection using kernel param
Current OMAP code supports couple of clocksource options based
on compilation flag (CONFIG_OMAP_32K_TIMER). The 32KHz sync-timer
and a gptimer which can run on 32KHz or system clock (e.g 38.4 MHz).
So there can be 3 options -
1. 32KHz sync-timer
2. Sys_clock based (e.g 13/19.2/26/38.4 MHz) gptimer
3. 32KHz based gptimer.
The optional gptimer based clocksource was added so that it can
give the high precision than sync-timer, so expected usage was 2
and not 3.
Unfortunately option 2, clocksource doesn't meet the requirement of
free-running clock as per clocksource need. It stops in low power states
when sys_clock is cut. That makes gptimer based clocksource option
useless for OMAP2/3/4 devices with sys_clock as a clock input.
So, in order to use option 2, deeper idle state MUST be disabled.
Option 3 will still work but it is no better than 32K sync-timer
based clocksource.
We must support both sync timer and gptimer based clocksource as
some OMAP based derivative SoCs like AM33XX does not have the
sync timer.
Considering above, make sync-timer and gptimer clocksource runtime
selectable so that both OMAP and AMXXXX continue to use the same code.
And, in order to precisely configure/setup sched_clock for given
clocksource, decision has to be made early enough in boot sequence.
So, the solution is,
Use standard kernel parameter ("clocksource=") to override
default 32k_sync-timer, in addition to this, we also use hwmod database
lookup mechanism, through which at run-time we can identify availability
of 32k-sync timer on the device, else fall back to gptimer.
Also, moved low-level SoC specific init code to respective files,
(mach-omap1/timer32k.c and mach-omap2/timer.c)
Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tarun Kanti DebBarma <tarun.kanti@ti.com>
Cc: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
2012-05-09 19:07:05 +02:00
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static void __iomem *sync32k_cnt_reg;
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2010-10-08 19:40:19 +02:00
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2011-12-15 12:19:23 +01:00
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static u32 notrace omap_32k_read_sched_clock(void)
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2010-10-08 19:40:19 +02:00
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{
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ARM: OMAP: Make OMAP clocksource source selection using kernel param
Current OMAP code supports couple of clocksource options based
on compilation flag (CONFIG_OMAP_32K_TIMER). The 32KHz sync-timer
and a gptimer which can run on 32KHz or system clock (e.g 38.4 MHz).
So there can be 3 options -
1. 32KHz sync-timer
2. Sys_clock based (e.g 13/19.2/26/38.4 MHz) gptimer
3. 32KHz based gptimer.
The optional gptimer based clocksource was added so that it can
give the high precision than sync-timer, so expected usage was 2
and not 3.
Unfortunately option 2, clocksource doesn't meet the requirement of
free-running clock as per clocksource need. It stops in low power states
when sys_clock is cut. That makes gptimer based clocksource option
useless for OMAP2/3/4 devices with sys_clock as a clock input.
So, in order to use option 2, deeper idle state MUST be disabled.
Option 3 will still work but it is no better than 32K sync-timer
based clocksource.
We must support both sync timer and gptimer based clocksource as
some OMAP based derivative SoCs like AM33XX does not have the
sync timer.
Considering above, make sync-timer and gptimer clocksource runtime
selectable so that both OMAP and AMXXXX continue to use the same code.
And, in order to precisely configure/setup sched_clock for given
clocksource, decision has to be made early enough in boot sequence.
So, the solution is,
Use standard kernel parameter ("clocksource=") to override
default 32k_sync-timer, in addition to this, we also use hwmod database
lookup mechanism, through which at run-time we can identify availability
of 32k-sync timer on the device, else fall back to gptimer.
Also, moved low-level SoC specific init code to respective files,
(mach-omap1/timer32k.c and mach-omap2/timer.c)
Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tarun Kanti DebBarma <tarun.kanti@ti.com>
Cc: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
2012-05-09 19:07:05 +02:00
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return sync32k_cnt_reg ? __raw_readl(sync32k_cnt_reg) : 0;
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2010-10-08 19:40:19 +02:00
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}
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/**
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2012-05-05 20:28:44 +02:00
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* omap_read_persistent_clock - Return time from a persistent clock.
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2010-10-08 19:40:19 +02:00
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*
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* Reads the time from a source which isn't disabled during PM, the
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* 32k sync timer. Convert the cycles elapsed since last read into
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* nsecs and adds to a monotonically increasing timespec.
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*/
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static struct timespec persistent_ts;
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2012-10-08 23:01:12 +02:00
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static cycles_t cycles;
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2011-07-11 08:05:34 +02:00
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static unsigned int persistent_mult, persistent_shift;
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2012-10-08 23:01:12 +02:00
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static DEFINE_SPINLOCK(read_persistent_clock_lock);
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2012-05-05 20:28:44 +02:00
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static void omap_read_persistent_clock(struct timespec *ts)
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2010-10-08 19:40:19 +02:00
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{
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unsigned long long nsecs;
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2012-10-08 23:01:12 +02:00
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cycles_t last_cycles;
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unsigned long flags;
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spin_lock_irqsave(&read_persistent_clock_lock, flags);
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2010-10-08 19:40:19 +02:00
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last_cycles = cycles;
|
ARM: OMAP: Make OMAP clocksource source selection using kernel param
Current OMAP code supports couple of clocksource options based
on compilation flag (CONFIG_OMAP_32K_TIMER). The 32KHz sync-timer
and a gptimer which can run on 32KHz or system clock (e.g 38.4 MHz).
So there can be 3 options -
1. 32KHz sync-timer
2. Sys_clock based (e.g 13/19.2/26/38.4 MHz) gptimer
3. 32KHz based gptimer.
The optional gptimer based clocksource was added so that it can
give the high precision than sync-timer, so expected usage was 2
and not 3.
Unfortunately option 2, clocksource doesn't meet the requirement of
free-running clock as per clocksource need. It stops in low power states
when sys_clock is cut. That makes gptimer based clocksource option
useless for OMAP2/3/4 devices with sys_clock as a clock input.
So, in order to use option 2, deeper idle state MUST be disabled.
Option 3 will still work but it is no better than 32K sync-timer
based clocksource.
We must support both sync timer and gptimer based clocksource as
some OMAP based derivative SoCs like AM33XX does not have the
sync timer.
Considering above, make sync-timer and gptimer clocksource runtime
selectable so that both OMAP and AMXXXX continue to use the same code.
And, in order to precisely configure/setup sched_clock for given
clocksource, decision has to be made early enough in boot sequence.
So, the solution is,
Use standard kernel parameter ("clocksource=") to override
default 32k_sync-timer, in addition to this, we also use hwmod database
lookup mechanism, through which at run-time we can identify availability
of 32k-sync timer on the device, else fall back to gptimer.
Also, moved low-level SoC specific init code to respective files,
(mach-omap1/timer32k.c and mach-omap2/timer.c)
Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tarun Kanti DebBarma <tarun.kanti@ti.com>
Cc: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
2012-05-09 19:07:05 +02:00
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cycles = sync32k_cnt_reg ? __raw_readl(sync32k_cnt_reg) : 0;
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2010-10-08 19:40:19 +02:00
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2012-10-08 23:01:12 +02:00
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nsecs = clocksource_cyc2ns(cycles - last_cycles,
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persistent_mult, persistent_shift);
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timespec_add_ns(&persistent_ts, nsecs);
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*ts = persistent_ts;
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2010-10-08 19:40:19 +02:00
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2012-10-08 23:01:12 +02:00
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spin_unlock_irqrestore(&read_persistent_clock_lock, flags);
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2010-10-08 19:40:19 +02:00
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}
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|
ARM: OMAP: Make OMAP clocksource source selection using kernel param
Current OMAP code supports couple of clocksource options based
on compilation flag (CONFIG_OMAP_32K_TIMER). The 32KHz sync-timer
and a gptimer which can run on 32KHz or system clock (e.g 38.4 MHz).
So there can be 3 options -
1. 32KHz sync-timer
2. Sys_clock based (e.g 13/19.2/26/38.4 MHz) gptimer
3. 32KHz based gptimer.
The optional gptimer based clocksource was added so that it can
give the high precision than sync-timer, so expected usage was 2
and not 3.
Unfortunately option 2, clocksource doesn't meet the requirement of
free-running clock as per clocksource need. It stops in low power states
when sys_clock is cut. That makes gptimer based clocksource option
useless for OMAP2/3/4 devices with sys_clock as a clock input.
So, in order to use option 2, deeper idle state MUST be disabled.
Option 3 will still work but it is no better than 32K sync-timer
based clocksource.
We must support both sync timer and gptimer based clocksource as
some OMAP based derivative SoCs like AM33XX does not have the
sync timer.
Considering above, make sync-timer and gptimer clocksource runtime
selectable so that both OMAP and AMXXXX continue to use the same code.
And, in order to precisely configure/setup sched_clock for given
clocksource, decision has to be made early enough in boot sequence.
So, the solution is,
Use standard kernel parameter ("clocksource=") to override
default 32k_sync-timer, in addition to this, we also use hwmod database
lookup mechanism, through which at run-time we can identify availability
of 32k-sync timer on the device, else fall back to gptimer.
Also, moved low-level SoC specific init code to respective files,
(mach-omap1/timer32k.c and mach-omap2/timer.c)
Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tarun Kanti DebBarma <tarun.kanti@ti.com>
Cc: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
2012-05-09 19:07:05 +02:00
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/**
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* omap_init_clocksource_32k - setup and register counter 32k as a
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* kernel clocksource
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* @pbase: base addr of counter_32k module
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* @size: size of counter_32k to map
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*
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* Returns 0 upon success or negative error code upon failure.
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*
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*/
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int __init omap_init_clocksource_32k(void __iomem *vbase)
|
2010-10-08 19:40:19 +02:00
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{
|
ARM: OMAP: Make OMAP clocksource source selection using kernel param
Current OMAP code supports couple of clocksource options based
on compilation flag (CONFIG_OMAP_32K_TIMER). The 32KHz sync-timer
and a gptimer which can run on 32KHz or system clock (e.g 38.4 MHz).
So there can be 3 options -
1. 32KHz sync-timer
2. Sys_clock based (e.g 13/19.2/26/38.4 MHz) gptimer
3. 32KHz based gptimer.
The optional gptimer based clocksource was added so that it can
give the high precision than sync-timer, so expected usage was 2
and not 3.
Unfortunately option 2, clocksource doesn't meet the requirement of
free-running clock as per clocksource need. It stops in low power states
when sys_clock is cut. That makes gptimer based clocksource option
useless for OMAP2/3/4 devices with sys_clock as a clock input.
So, in order to use option 2, deeper idle state MUST be disabled.
Option 3 will still work but it is no better than 32K sync-timer
based clocksource.
We must support both sync timer and gptimer based clocksource as
some OMAP based derivative SoCs like AM33XX does not have the
sync timer.
Considering above, make sync-timer and gptimer clocksource runtime
selectable so that both OMAP and AMXXXX continue to use the same code.
And, in order to precisely configure/setup sched_clock for given
clocksource, decision has to be made early enough in boot sequence.
So, the solution is,
Use standard kernel parameter ("clocksource=") to override
default 32k_sync-timer, in addition to this, we also use hwmod database
lookup mechanism, through which at run-time we can identify availability
of 32k-sync timer on the device, else fall back to gptimer.
Also, moved low-level SoC specific init code to respective files,
(mach-omap1/timer32k.c and mach-omap2/timer.c)
Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tarun Kanti DebBarma <tarun.kanti@ti.com>
Cc: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
2012-05-09 19:07:05 +02:00
|
|
|
int ret;
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/*
|
2012-05-10 10:47:22 +02:00
|
|
|
* 32k sync Counter IP register offsets vary between the
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|
|
* highlander version and the legacy ones.
|
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* The 'SCHEME' bits(30-31) of the revision register is used
|
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* to identify the version.
|
ARM: OMAP: Make OMAP clocksource source selection using kernel param
Current OMAP code supports couple of clocksource options based
on compilation flag (CONFIG_OMAP_32K_TIMER). The 32KHz sync-timer
and a gptimer which can run on 32KHz or system clock (e.g 38.4 MHz).
So there can be 3 options -
1. 32KHz sync-timer
2. Sys_clock based (e.g 13/19.2/26/38.4 MHz) gptimer
3. 32KHz based gptimer.
The optional gptimer based clocksource was added so that it can
give the high precision than sync-timer, so expected usage was 2
and not 3.
Unfortunately option 2, clocksource doesn't meet the requirement of
free-running clock as per clocksource need. It stops in low power states
when sys_clock is cut. That makes gptimer based clocksource option
useless for OMAP2/3/4 devices with sys_clock as a clock input.
So, in order to use option 2, deeper idle state MUST be disabled.
Option 3 will still work but it is no better than 32K sync-timer
based clocksource.
We must support both sync timer and gptimer based clocksource as
some OMAP based derivative SoCs like AM33XX does not have the
sync timer.
Considering above, make sync-timer and gptimer clocksource runtime
selectable so that both OMAP and AMXXXX continue to use the same code.
And, in order to precisely configure/setup sched_clock for given
clocksource, decision has to be made early enough in boot sequence.
So, the solution is,
Use standard kernel parameter ("clocksource=") to override
default 32k_sync-timer, in addition to this, we also use hwmod database
lookup mechanism, through which at run-time we can identify availability
of 32k-sync timer on the device, else fall back to gptimer.
Also, moved low-level SoC specific init code to respective files,
(mach-omap1/timer32k.c and mach-omap2/timer.c)
Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tarun Kanti DebBarma <tarun.kanti@ti.com>
Cc: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
2012-05-09 19:07:05 +02:00
|
|
|
*/
|
2012-05-10 10:47:22 +02:00
|
|
|
if (__raw_readl(vbase + OMAP2_32KSYNCNT_REV_OFF) &
|
|
|
|
OMAP2_32KSYNCNT_REV_SCHEME)
|
|
|
|
sync32k_cnt_reg = vbase + OMAP2_32KSYNCNT_CR_OFF_HIGH;
|
|
|
|
else
|
|
|
|
sync32k_cnt_reg = vbase + OMAP2_32KSYNCNT_CR_OFF_LOW;
|
ARM: OMAP: Make OMAP clocksource source selection using kernel param
Current OMAP code supports couple of clocksource options based
on compilation flag (CONFIG_OMAP_32K_TIMER). The 32KHz sync-timer
and a gptimer which can run on 32KHz or system clock (e.g 38.4 MHz).
So there can be 3 options -
1. 32KHz sync-timer
2. Sys_clock based (e.g 13/19.2/26/38.4 MHz) gptimer
3. 32KHz based gptimer.
The optional gptimer based clocksource was added so that it can
give the high precision than sync-timer, so expected usage was 2
and not 3.
Unfortunately option 2, clocksource doesn't meet the requirement of
free-running clock as per clocksource need. It stops in low power states
when sys_clock is cut. That makes gptimer based clocksource option
useless for OMAP2/3/4 devices with sys_clock as a clock input.
So, in order to use option 2, deeper idle state MUST be disabled.
Option 3 will still work but it is no better than 32K sync-timer
based clocksource.
We must support both sync timer and gptimer based clocksource as
some OMAP based derivative SoCs like AM33XX does not have the
sync timer.
Considering above, make sync-timer and gptimer clocksource runtime
selectable so that both OMAP and AMXXXX continue to use the same code.
And, in order to precisely configure/setup sched_clock for given
clocksource, decision has to be made early enough in boot sequence.
So, the solution is,
Use standard kernel parameter ("clocksource=") to override
default 32k_sync-timer, in addition to this, we also use hwmod database
lookup mechanism, through which at run-time we can identify availability
of 32k-sync timer on the device, else fall back to gptimer.
Also, moved low-level SoC specific init code to respective files,
(mach-omap1/timer32k.c and mach-omap2/timer.c)
Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tarun Kanti DebBarma <tarun.kanti@ti.com>
Cc: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
2012-05-09 19:07:05 +02:00
|
|
|
|
|
|
|
/*
|
|
|
|
* 120000 rough estimate from the calculations in
|
|
|
|
* __clocksource_updatefreq_scale.
|
|
|
|
*/
|
|
|
|
clocks_calc_mult_shift(&persistent_mult, &persistent_shift,
|
|
|
|
32768, NSEC_PER_SEC, 120000);
|
|
|
|
|
|
|
|
ret = clocksource_mmio_init(sync32k_cnt_reg, "32k_counter", 32768,
|
|
|
|
250, 32, clocksource_mmio_readl_up);
|
|
|
|
if (ret) {
|
|
|
|
pr_err("32k_counter: can't register clocksource\n");
|
|
|
|
return ret;
|
2010-10-08 19:40:19 +02:00
|
|
|
}
|
ARM: OMAP: Make OMAP clocksource source selection using kernel param
Current OMAP code supports couple of clocksource options based
on compilation flag (CONFIG_OMAP_32K_TIMER). The 32KHz sync-timer
and a gptimer which can run on 32KHz or system clock (e.g 38.4 MHz).
So there can be 3 options -
1. 32KHz sync-timer
2. Sys_clock based (e.g 13/19.2/26/38.4 MHz) gptimer
3. 32KHz based gptimer.
The optional gptimer based clocksource was added so that it can
give the high precision than sync-timer, so expected usage was 2
and not 3.
Unfortunately option 2, clocksource doesn't meet the requirement of
free-running clock as per clocksource need. It stops in low power states
when sys_clock is cut. That makes gptimer based clocksource option
useless for OMAP2/3/4 devices with sys_clock as a clock input.
So, in order to use option 2, deeper idle state MUST be disabled.
Option 3 will still work but it is no better than 32K sync-timer
based clocksource.
We must support both sync timer and gptimer based clocksource as
some OMAP based derivative SoCs like AM33XX does not have the
sync timer.
Considering above, make sync-timer and gptimer clocksource runtime
selectable so that both OMAP and AMXXXX continue to use the same code.
And, in order to precisely configure/setup sched_clock for given
clocksource, decision has to be made early enough in boot sequence.
So, the solution is,
Use standard kernel parameter ("clocksource=") to override
default 32k_sync-timer, in addition to this, we also use hwmod database
lookup mechanism, through which at run-time we can identify availability
of 32k-sync timer on the device, else fall back to gptimer.
Also, moved low-level SoC specific init code to respective files,
(mach-omap1/timer32k.c and mach-omap2/timer.c)
Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tarun Kanti DebBarma <tarun.kanti@ti.com>
Cc: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
2012-05-09 19:07:05 +02:00
|
|
|
|
|
|
|
setup_sched_clock(omap_32k_read_sched_clock, 32, 32768);
|
2012-05-26 21:31:49 +02:00
|
|
|
register_persistent_clock(NULL, omap_read_persistent_clock);
|
ARM: OMAP: Make OMAP clocksource source selection using kernel param
Current OMAP code supports couple of clocksource options based
on compilation flag (CONFIG_OMAP_32K_TIMER). The 32KHz sync-timer
and a gptimer which can run on 32KHz or system clock (e.g 38.4 MHz).
So there can be 3 options -
1. 32KHz sync-timer
2. Sys_clock based (e.g 13/19.2/26/38.4 MHz) gptimer
3. 32KHz based gptimer.
The optional gptimer based clocksource was added so that it can
give the high precision than sync-timer, so expected usage was 2
and not 3.
Unfortunately option 2, clocksource doesn't meet the requirement of
free-running clock as per clocksource need. It stops in low power states
when sys_clock is cut. That makes gptimer based clocksource option
useless for OMAP2/3/4 devices with sys_clock as a clock input.
So, in order to use option 2, deeper idle state MUST be disabled.
Option 3 will still work but it is no better than 32K sync-timer
based clocksource.
We must support both sync timer and gptimer based clocksource as
some OMAP based derivative SoCs like AM33XX does not have the
sync timer.
Considering above, make sync-timer and gptimer clocksource runtime
selectable so that both OMAP and AMXXXX continue to use the same code.
And, in order to precisely configure/setup sched_clock for given
clocksource, decision has to be made early enough in boot sequence.
So, the solution is,
Use standard kernel parameter ("clocksource=") to override
default 32k_sync-timer, in addition to this, we also use hwmod database
lookup mechanism, through which at run-time we can identify availability
of 32k-sync timer on the device, else fall back to gptimer.
Also, moved low-level SoC specific init code to respective files,
(mach-omap1/timer32k.c and mach-omap2/timer.c)
Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tarun Kanti DebBarma <tarun.kanti@ti.com>
Cc: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
2012-05-09 19:07:05 +02:00
|
|
|
pr_info("OMAP clocksource: 32k_counter at 32768 Hz\n");
|
|
|
|
|
2010-10-08 19:40:19 +02:00
|
|
|
return 0;
|
|
|
|
}
|