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Date: Fri, 30 Apr 2010 18:36:25 -0700
From: John Stultz <johnstul@...ibm.com>
To: lkml <linux-kernel@...r.kernel.org>
Cc: John Stultz <johnstul@...ibm.com>,
Ralf Baechle <ralf@...ux-mips.org>,
Martin Schwidefsky <schwidefsky@...ibm.com>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mundt <lethal@...ux-sh.org>,
Jim Cromie <jim.cromie@...il.com>,
Thomas Gleixner <tglx@...utronix.de>
Subject: [RFC][PATCH 3/3] Try to convert non-trivial clocksources to clocksource_register_hz
NOT FOR INCLUSION!
NOT FOR INCLUSION!
I've already gone through and converted the rest of the clocksources
to use clocksource_register_hz, and I'll be hopefully pushing those
to arch maintainers for 2.6.36-2.6.37.
However, in going through all the clocksources, I hit a few
non-trivial conversions and wanted to bring them up on the list
early so they can be handled soon.
The following patch tries to convert the non-trival clocksources
to use clocksource_register_hz/khz. It is likely broken. I will
need arch maintainer help to figure out the best way to resovle
these clocksources.
This patch requires the previous "Add clocksource_register_hz/khz
interface" patch to build.
So any help maintainers can provide in finding solutions to
break the mult/shift assumptions in the arch code would be
greatly appreciated!
thanks
-john
NOT FOR INCLUSION!
NOT FOR INCLUSION!
CC: Ralf Baechle <ralf@...ux-mips.org>
CC: Martin Schwidefsky <schwidefsky@...ibm.com>
CC: Benjamin Herrenschmidt <benh@...nel.crashing.org>
CC: Paul Mundt <lethal@...ux-sh.org>
CC: Jim Cromie <jim.cromie@...il.com>
CC: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: John Stultz <johnstul@...ibm.com>
---
arch/mips/nxp/pnx8550/common/time.c | 7 ++++++-
arch/powerpc/kernel/time.c | 14 +++++++-------
arch/s390/kernel/time.c | 13 ++++++++++---
drivers/clocksource/scx200_hrt.c | 19 ++++++-------------
drivers/clocksource/sh_cmt.c | 4 ++--
drivers/clocksource/sh_tmu.c | 4 ++--
kernel/time/jiffies.c | 3 ++-
7 files changed, 35 insertions(+), 29 deletions(-)
diff --git a/arch/mips/nxp/pnx8550/common/time.c b/arch/mips/nxp/pnx8550/common/time.c
index 8836c62..a4420f0 100644
--- a/arch/mips/nxp/pnx8550/common/time.c
+++ b/arch/mips/nxp/pnx8550/common/time.c
@@ -104,7 +104,12 @@ __init void plat_time_init(void)
pnx8xxx_clockevent.cpumask = cpu_none_mask;
clockevents_register_device(&pnx8xxx_clockevent);
- clocksource_register(&pnx_clocksource);
+
+ /*
+ * XXX - Nothing seems to set pnx_clocksource mult/shift!
+ * So I don't know what freq to use here. Help! -johnstul
+ */
+ clocksource_register_hz(&pnx_clocksource, 0);
/* Timer 1 start */
configPR = read_c0_config7();
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 1b16b9a..827abe6 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -86,8 +86,6 @@ static struct clocksource clocksource_rtc = {
.rating = 400,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
.mask = CLOCKSOURCE_MASK(64),
- .shift = 22,
- .mult = 0, /* To be filled in */
.read = rtc_read,
};
@@ -97,8 +95,6 @@ static struct clocksource clocksource_timebase = {
.rating = 400,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
.mask = CLOCKSOURCE_MASK(64),
- .shift = 22,
- .mult = 0, /* To be filled in */
.read = timebase_read,
};
@@ -848,6 +844,12 @@ void update_vsyscall(struct timespec *wall_time, struct clocksource *clock,
/* Make userspace gettimeofday spin until we're done. */
++vdso_data->tb_update_count;
smp_mb();
+
+ /*
+ * XXX UGH! the below assumes clock->shift == 22.
+ * This will no longer be the case with clocksource_register_hz
+ * HELP! -johnstul
+ */
/* XXX this assumes clock->shift == 22 */
/* 4611686018 ~= 2^(20+64-22) / 1e9 */
@@ -878,9 +880,7 @@ static void __init clocksource_init(void)
else
clock = &clocksource_timebase;
- clock->mult = clocksource_hz2mult(tb_ticks_per_sec, clock->shift);
-
- if (clocksource_register(clock)) {
+ if (clocksource_register_hz(clock, tb_ticks_per_sec)) {
printk(KERN_ERR "clocksource: %s is already registered\n",
clock->name);
return;
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index d906bf1..6412752 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -197,8 +197,6 @@ static struct clocksource clocksource_tod = {
.rating = 400,
.read = read_tod_clock,
.mask = -1ULL,
- .mult = 1000,
- .shift = 12,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
@@ -257,7 +255,16 @@ void __init time_init(void)
if (register_external_interrupt(0x1406, timing_alert_interrupt))
panic("Couldn't request external interrupt 0x1406");
- if (clocksource_register(&clocksource_tod) != 0)
+ /*
+ * XXX - Brute forced tod freq from:
+ * 2^shift/mult * NSEC_PER_SEC = cyc/sec
+ * 2^12 / 1000 * 1000000000 = cyc/sec
+ * 2^12 * 1000000 = cyc/sec
+ * 2^12 * 1000 = kcyc/sec
+ * 1000<<12 = kcyc/sec
+ * Could be totally wrong. -johnstul
+ */
+ if (clocksource_register_khz(&clocksource_tod, (1000<<12) ) != 0)
panic("Could not register TOD clock source");
/* Enable TOD clock interrupts on the boot cpu. */
diff --git a/drivers/clocksource/scx200_hrt.c b/drivers/clocksource/scx200_hrt.c
index 27f4d96..24f884c 100644
--- a/drivers/clocksource/scx200_hrt.c
+++ b/drivers/clocksource/scx200_hrt.c
@@ -49,9 +49,6 @@ static cycle_t read_hrt(struct clocksource *cs)
return (cycle_t) inl(scx200_cb_base + SCx200_TIMER_OFFSET);
}
-#define HRT_SHIFT_1 22
-#define HRT_SHIFT_27 26
-
static struct clocksource cs_hrt = {
.name = "scx200_hrt",
.rating = 250,
@@ -63,6 +60,7 @@ static struct clocksource cs_hrt = {
static int __init init_hrt_clocksource(void)
{
+ u32 freq;
/* Make sure scx200 has initialized the configuration block */
if (!scx200_cb_present())
return -ENODEV;
@@ -79,19 +77,14 @@ static int __init init_hrt_clocksource(void)
outb(HR_TMEN | (mhz27 ? HR_TMCLKSEL : 0),
scx200_cb_base + SCx200_TMCNFG_OFFSET);
- if (mhz27) {
- cs_hrt.shift = HRT_SHIFT_27;
- cs_hrt.mult = clocksource_hz2mult((HRT_FREQ + ppm) * 27,
- cs_hrt.shift);
- } else {
- cs_hrt.shift = HRT_SHIFT_1;
- cs_hrt.mult = clocksource_hz2mult(HRT_FREQ + ppm,
- cs_hrt.shift);
- }
+ freq = (HRT_FREQ + ppm);
+ if (mhz27)
+ freq *= 27;
+
printk(KERN_INFO "enabling scx200 high-res timer (%s MHz +%d ppm)\n",
mhz27 ? "27":"1", ppm);
- return clocksource_register(&cs_hrt);
+ return clocksource_register_hz(&cs_hrt, freq);
}
module_init(init_hrt_clocksource);
diff --git a/drivers/clocksource/sh_cmt.c b/drivers/clocksource/sh_cmt.c
index 744f748..23bb543 100644
--- a/drivers/clocksource/sh_cmt.c
+++ b/drivers/clocksource/sh_cmt.c
@@ -422,7 +422,6 @@ static int sh_cmt_clocksource_enable(struct clocksource *cs)
return ret;
/* TODO: calculate good shift from rate and counter bit width */
- cs->shift = 0;
cs->mult = clocksource_hz2mult(p->rate, cs->shift);
return 0;
}
@@ -452,7 +451,8 @@ static int sh_cmt_register_clocksource(struct sh_cmt_priv *p,
cs->mask = CLOCKSOURCE_MASK(sizeof(unsigned long) * 8);
cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
pr_info("sh_cmt: %s used as clock source\n", cs->name);
- clocksource_register(cs);
+ /* XXX - What do we do about rate changes? -johnstul */
+ clocksource_register_hz(cs, p->rate);
return 0;
}
diff --git a/drivers/clocksource/sh_tmu.c b/drivers/clocksource/sh_tmu.c
index fc9ff1e..5d7f947 100644
--- a/drivers/clocksource/sh_tmu.c
+++ b/drivers/clocksource/sh_tmu.c
@@ -207,7 +207,6 @@ static int sh_tmu_clocksource_enable(struct clocksource *cs)
return ret;
/* TODO: calculate good shift from rate and counter bit width */
- cs->shift = 10;
cs->mult = clocksource_hz2mult(p->rate, cs->shift);
return 0;
}
@@ -230,7 +229,8 @@ static int sh_tmu_register_clocksource(struct sh_tmu_priv *p,
cs->mask = CLOCKSOURCE_MASK(32);
cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
pr_info("sh_tmu: %s used as clock source\n", cs->name);
- clocksource_register(cs);
+ /* XXX - What do we do about the rate changes in enable/disable? */
+ clocksource_register_hz(cs, p->rate);
return 0;
}
diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c
index 5404a84..73b0a86 100644
--- a/kernel/time/jiffies.c
+++ b/kernel/time/jiffies.c
@@ -66,7 +66,8 @@ struct clocksource clocksource_jiffies = {
static int __init init_jiffies_clocksource(void)
{
- return clocksource_register(&clocksource_jiffies);
+ /* XXX - HRMMM.. we're losing some precision since ACTHZ>>8 != HZ */
+ return clocksource_register_hz(&clocksource_jiffies, HZ);
}
core_initcall(init_jiffies_clocksource);
--
1.6.0.4
--
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