[PATCH v3 0/7] ARM: zynq: cpufreq support

[PATCH v3 0/7] ARM: zynq: cpufreq support

[Soren Brinkmann]

Hi,

the merge window is over and ARM is also booting again. So, time to
restart the discussion on this series.
I rebased the series on 3.14-rc1 which removed some of the patches of
the original submission due to them already having been merged.
Other than that, I didn't do many changes compared to the patches that
have been sent out in early December. Changelogs are included with the
patches.

	Thanks,
	Sören

Soren Brinkmann (7):
  time: Serialize calls to 'clockevents_update_freq' in the timing core
  time: clockevents: Adjust timer interval when frequency changes
  clocksource/cadence_ttc: Call clockevents_update_freq() with IRQs
    enabled
  clocksource/cadence_ttc: Overhaul clocksource frequency adjustment
  clocksource/cadence_ttc: Use only one counter
  arm: zynq: Don't use arm_global_timer with cpufreq
  arm: zynq: Add support for cpufreq

 arch/arm/boot/dts/zynq-7000.dtsi        |   6 +
 arch/arm/mach-zynq/Kconfig              |   4 +-
 arch/arm/mach-zynq/common.c             |   3 +
 drivers/clocksource/cadence_ttc_timer.c | 213 ++++++++++++++++++--------------
 kernel/time/clockevents.c               |  32 +++--
 kernel/time/tick-broadcast.c            |  25 +++-
 kernel/time/tick-internal.h             |   4 +
 7 files changed, 177 insertions(+), 110 deletions(-)

-- 
1.8.5.3

[PATCH v3 1/7] time: Serialize calls to 'clockevents_update_freq' in the timing core

[Soren Brinkmann]

From: Thomas Gleixner <tglx@linutronix.de>

We can identify the broadcast device in the core and serialize all
callers including interrupts on a different CPU against the update.
Also, disabling interrupts is moved into the core allowing callers to
leave interrutps enabled when calling clockevents_update_freq().

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
 kernel/time/clockevents.c    | 29 ++++++++++++++++++++++-------
 kernel/time/tick-broadcast.c | 25 +++++++++++++++++++------
 kernel/time/tick-internal.h  |  4 ++++
 3 files changed, 45 insertions(+), 13 deletions(-)

diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index 086ad6043bcb..641d91003a45 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -439,6 +439,16 @@ void clockevents_config_and_register(struct clock_event_device *dev,
 }
 EXPORT_SYMBOL_GPL(clockevents_config_and_register);
 
+int __clockevents_update_freq(struct clock_event_device *dev, u32 freq)
+{
+	clockevents_config(dev, freq);
+
+	if (dev->mode != CLOCK_EVT_MODE_ONESHOT)
+		return 0;
+
+	return clockevents_program_event(dev, dev->next_event, false);
+}
+
 /**
  * clockevents_update_freq - Update frequency and reprogram a clock event device.
  * @dev:	device to modify
@@ -446,17 +456,22 @@ EXPORT_SYMBOL_GPL(clockevents_config_and_register);
  *
  * Reconfigure and reprogram a clock event device in oneshot
  * mode. Must be called on the cpu for which the device delivers per
- * cpu timer events with interrupts disabled!  Returns 0 on success,
- * -ETIME when the event is in the past.
+ * cpu timer events. If called for the broadcast device the core takes
+ * care of serialization.
+ *
+ * Returns 0 on success, -ETIME when the event is in the past.
  */
 int clockevents_update_freq(struct clock_event_device *dev, u32 freq)
 {
-	clockevents_config(dev, freq);
-
-	if (dev->mode != CLOCK_EVT_MODE_ONESHOT)
-		return 0;
+	unsigned long flags;
+	int ret;
 
-	return clockevents_program_event(dev, dev->next_event, false);
+	local_irq_save(flags);
+	ret = tick_broadcast_update_freq(dev, freq);
+	if (ret == -ENODEV)
+		ret = __clockevents_update_freq(dev, freq);
+	local_irq_restore(flags);
+	return ret;
 }
 
 /*
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 43780ab5e279..003e6c3663b1 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -120,6 +120,19 @@ int tick_is_broadcast_device(struct clock_event_device *dev)
 	return (dev && tick_broadcast_device.evtdev == dev);
 }
 
+int tick_broadcast_update_freq(struct clock_event_device *dev, u32 freq)
+{
+	int ret = -ENODEV;
+
+	if (tick_is_broadcast_device(dev)) {
+		raw_spin_lock(&tick_broadcast_lock);
+		ret = __clockevents_update_freq(dev, freq);
+		raw_spin_unlock(&tick_broadcast_lock);
+	}
+	return ret;
+}
+
+
 static void err_broadcast(const struct cpumask *mask)
 {
 	pr_crit_once("Failed to broadcast timer tick. Some CPUs may be unresponsive.\n");
@@ -272,12 +285,8 @@ static void tick_do_broadcast(struct cpumask *mask)
  */
 static void tick_do_periodic_broadcast(void)
 {
-	raw_spin_lock(&tick_broadcast_lock);
-
 	cpumask_and(tmpmask, cpu_online_mask, tick_broadcast_mask);
 	tick_do_broadcast(tmpmask);
-
-	raw_spin_unlock(&tick_broadcast_lock);
 }
 
 /*
@@ -287,13 +296,15 @@ static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
 {
 	ktime_t next;
 
+	raw_spin_lock(&tick_broadcast_lock);
+
 	tick_do_periodic_broadcast();
 
 	/*
 	 * The device is in periodic mode. No reprogramming necessary:
 	 */
 	if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
-		return;
+		goto unlock;
 
 	/*
 	 * Setup the next period for devices, which do not have
@@ -306,9 +317,11 @@ static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
 		next = ktime_add(next, tick_period);
 
 		if (!clockevents_program_event(dev, next, false))
-			return;
+			goto unlock;
 		tick_do_periodic_broadcast();
 	}
+unlock:
+	raw_spin_unlock(&tick_broadcast_lock);
 }
 
 /*
diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
index 8329669b51ec..26f1c0ba9d81 100644
--- a/kernel/time/tick-internal.h
+++ b/kernel/time/tick-internal.h
@@ -111,6 +111,7 @@ extern int tick_resume_broadcast(void);
 extern void tick_broadcast_init(void);
 extern void
 tick_set_periodic_handler(struct clock_event_device *dev, int broadcast);
+int tick_broadcast_update_freq(struct clock_event_device *dev, u32 freq);
 
 #else /* !BROADCAST */
 
@@ -133,6 +134,8 @@ static inline void tick_shutdown_broadcast(unsigned int *cpup) { }
 static inline void tick_suspend_broadcast(void) { }
 static inline int tick_resume_broadcast(void) { return 0; }
 static inline void tick_broadcast_init(void) { }
+static inline int tick_broadcast_update_freq(struct clock_event_device *dev,
+					     u32 freq) { return -ENODEV; }
 
 /*
  * Set the periodic handler in non broadcast mode
@@ -154,5 +157,6 @@ static inline int tick_device_is_functional(struct clock_event_device *dev)
 
 #endif
 
+int __clockevents_update_freq(struct clock_event_device *dev, u32 freq);
 extern void do_timer(unsigned long ticks);
 extern void update_wall_time(void);
-- 
1.8.5.3

[tip:timers/core] clockevents: Serialize calls to clockevents_update_freq() in the core

[tip-bot for Thomas Gleixner]

Commit-ID:  627ee7947e2e83ba565c31c5c9373d6e364b1ecd
Gitweb:     http://git.kernel.org/tip/627ee7947e2e83ba565c31c5c9373d6e364b1ecd
Author:     Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Mon, 3 Feb 2014 14:34:31 -0800
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 7 Feb 2014 15:34:28 +0100

clockevents: Serialize calls to clockevents_update_freq() in the core

We can identify the broadcast device in the core and serialize all
callers including interrupts on a different CPU against the update.
Also, disabling interrupts is moved into the core allowing callers to
leave interrutps enabled when calling clockevents_update_freq().

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Soeren Brinkmann <soren.brinkmann@xilinx.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Michal Simek <michal.simek@xilinx.com>
Link: http://lkml.kernel.org/r/1391466877-28908-2-git-send-email-soren.brinkmann@xilinx.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 kernel/time/clockevents.c    | 29 ++++++++++++++++++++++-------
 kernel/time/tick-broadcast.c | 25 +++++++++++++++++++------
 kernel/time/tick-internal.h  |  4 ++++
 3 files changed, 45 insertions(+), 13 deletions(-)

diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index 086ad60..641d910 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -439,6 +439,16 @@ void clockevents_config_and_register(struct clock_event_device *dev,
 }
 EXPORT_SYMBOL_GPL(clockevents_config_and_register);
 
+int __clockevents_update_freq(struct clock_event_device *dev, u32 freq)
+{
+	clockevents_config(dev, freq);
+
+	if (dev->mode != CLOCK_EVT_MODE_ONESHOT)
+		return 0;
+
+	return clockevents_program_event(dev, dev->next_event, false);
+}
+
 /**
  * clockevents_update_freq - Update frequency and reprogram a clock event device.
  * @dev:	device to modify
@@ -446,17 +456,22 @@ EXPORT_SYMBOL_GPL(clockevents_config_and_register);
  *
  * Reconfigure and reprogram a clock event device in oneshot
  * mode. Must be called on the cpu for which the device delivers per
- * cpu timer events with interrupts disabled!  Returns 0 on success,
- * -ETIME when the event is in the past.
+ * cpu timer events. If called for the broadcast device the core takes
+ * care of serialization.
+ *
+ * Returns 0 on success, -ETIME when the event is in the past.
  */
 int clockevents_update_freq(struct clock_event_device *dev, u32 freq)
 {
-	clockevents_config(dev, freq);
-
-	if (dev->mode != CLOCK_EVT_MODE_ONESHOT)
-		return 0;
+	unsigned long flags;
+	int ret;
 
-	return clockevents_program_event(dev, dev->next_event, false);
+	local_irq_save(flags);
+	ret = tick_broadcast_update_freq(dev, freq);
+	if (ret == -ENODEV)
+		ret = __clockevents_update_freq(dev, freq);
+	local_irq_restore(flags);
+	return ret;
 }
 
 /*
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 43780ab..003e6c3 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -120,6 +120,19 @@ int tick_is_broadcast_device(struct clock_event_device *dev)
 	return (dev && tick_broadcast_device.evtdev == dev);
 }
 
+int tick_broadcast_update_freq(struct clock_event_device *dev, u32 freq)
+{
+	int ret = -ENODEV;
+
+	if (tick_is_broadcast_device(dev)) {
+		raw_spin_lock(&tick_broadcast_lock);
+		ret = __clockevents_update_freq(dev, freq);
+		raw_spin_unlock(&tick_broadcast_lock);
+	}
+	return ret;
+}
+
+
 static void err_broadcast(const struct cpumask *mask)
 {
 	pr_crit_once("Failed to broadcast timer tick. Some CPUs may be unresponsive.\n");
@@ -272,12 +285,8 @@ static void tick_do_broadcast(struct cpumask *mask)
  */
 static void tick_do_periodic_broadcast(void)
 {
-	raw_spin_lock(&tick_broadcast_lock);
-
 	cpumask_and(tmpmask, cpu_online_mask, tick_broadcast_mask);
 	tick_do_broadcast(tmpmask);
-
-	raw_spin_unlock(&tick_broadcast_lock);
 }
 
 /*
@@ -287,13 +296,15 @@ static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
 {
 	ktime_t next;
 
+	raw_spin_lock(&tick_broadcast_lock);
+
 	tick_do_periodic_broadcast();
 
 	/*
 	 * The device is in periodic mode. No reprogramming necessary:
 	 */
 	if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
-		return;
+		goto unlock;
 
 	/*
 	 * Setup the next period for devices, which do not have
@@ -306,9 +317,11 @@ static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
 		next = ktime_add(next, tick_period);
 
 		if (!clockevents_program_event(dev, next, false))
-			return;
+			goto unlock;
 		tick_do_periodic_broadcast();
 	}
+unlock:
+	raw_spin_unlock(&tick_broadcast_lock);
 }
 
 /*
diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
index 8329669..26f1c0b 100644
--- a/kernel/time/tick-internal.h
+++ b/kernel/time/tick-internal.h
@@ -111,6 +111,7 @@ extern int tick_resume_broadcast(void);
 extern void tick_broadcast_init(void);
 extern void
 tick_set_periodic_handler(struct clock_event_device *dev, int broadcast);
+int tick_broadcast_update_freq(struct clock_event_device *dev, u32 freq);
 
 #else /* !BROADCAST */
 
@@ -133,6 +134,8 @@ static inline void tick_shutdown_broadcast(unsigned int *cpup) { }
 static inline void tick_suspend_broadcast(void) { }
 static inline int tick_resume_broadcast(void) { return 0; }
 static inline void tick_broadcast_init(void) { }
+static inline int tick_broadcast_update_freq(struct clock_event_device *dev,
+					     u32 freq) { return -ENODEV; }
 
 /*
  * Set the periodic handler in non broadcast mode
@@ -154,5 +157,6 @@ static inline int tick_device_is_functional(struct clock_event_device *dev)
 
 #endif
 
+int __clockevents_update_freq(struct clock_event_device *dev, u32 freq);
 extern void do_timer(unsigned long ticks);
 extern void update_wall_time(void);

[PATCH v3 2/7] time: clockevents: Adjust timer interval when frequency changes

[Soren Brinkmann]

To adjust the timer's interval in periodic mode, the clockevent device
is put into periodic mode during clockevents_update_freq() in case the
timer is in periodic mode.

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
It is assumed that simply calling the timer's 'set_mode()' API takes care of
programming an appropriate interval based on the current timer frequency.
If that doesn't work for all timers, I guess it might require a new API
call.
---
 kernel/time/clockevents.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index 641d91003a45..f85e5fda9c66 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -443,10 +443,13 @@ int __clockevents_update_freq(struct clock_event_device *dev, u32 freq)
 {
 	clockevents_config(dev, freq);
 
-	if (dev->mode != CLOCK_EVT_MODE_ONESHOT)
-		return 0;
+	if (dev->mode == CLOCK_EVT_MODE_ONESHOT)
+		return clockevents_program_event(dev, dev->next_event, false);
+
+	if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
+		dev->set_mode(CLOCK_EVT_MODE_PERIODIC, dev);
 
-	return clockevents_program_event(dev, dev->next_event, false);
+	return 0;
 }
 
 /**
-- 
1.8.5.3

[tip:timers/core] clockevents: Adjust timer interval when frequency changes

[tip-bot for Soren Brinkmann]

Commit-ID:  fe79a9ba11962a603fb6af68fcb476e64031e46c
Gitweb:     http://git.kernel.org/tip/fe79a9ba11962a603fb6af68fcb476e64031e46c
Author:     Soren Brinkmann <soren.brinkmann@xilinx.com>
AuthorDate: Mon, 3 Feb 2014 14:34:32 -0800
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 7 Feb 2014 15:34:29 +0100

clockevents: Adjust timer interval when frequency changes

clockevent devices in periodic mode are not updated when the frequency
of the device changes. Issue a dev->set_mode() callback which forces
the device to reevaluate the timer settings.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Michal Simek <michal.simek@xilinx.com>
Link: http://lkml.kernel.org/r/1391466877-28908-3-git-send-email-soren.brinkmann@xilinx.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 kernel/time/clockevents.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index 641d910..f85e5fd 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -443,10 +443,13 @@ int __clockevents_update_freq(struct clock_event_device *dev, u32 freq)
 {
 	clockevents_config(dev, freq);
 
-	if (dev->mode != CLOCK_EVT_MODE_ONESHOT)
-		return 0;
+	if (dev->mode == CLOCK_EVT_MODE_ONESHOT)
+		return clockevents_program_event(dev, dev->next_event, false);
+
+	if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
+		dev->set_mode(CLOCK_EVT_MODE_PERIODIC, dev);
 
-	return clockevents_program_event(dev, dev->next_event, false);
+	return 0;
 }
 
 /**

[PATCH v3 3/7] clocksource/cadence_ttc: Call clockevents_update_freq() with IRQs enabled

[Soren Brinkmann]

The timer core takes care of serialization and IRQs. Hence the driver is
no longer required to disable interrupts when calling
clockevents_update_freq().

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
 drivers/clocksource/cadence_ttc_timer.c | 17 ++---------------
 1 file changed, 2 insertions(+), 15 deletions(-)

diff --git a/drivers/clocksource/cadence_ttc_timer.c b/drivers/clocksource/cadence_ttc_timer.c
index 63f176de0d02..f05b9fdc7425 100644
--- a/drivers/clocksource/cadence_ttc_timer.c
+++ b/drivers/clocksource/cadence_ttc_timer.c
@@ -321,25 +321,12 @@ static int ttc_rate_change_clockevent_cb(struct notifier_block *nb,
 
 	switch (event) {
 	case POST_RATE_CHANGE:
-	{
-		unsigned long flags;
-
-		/*
-		 * clockevents_update_freq should be called with IRQ disabled on
-		 * the CPU the timer provides events for. The timer we use is
-		 * common to both CPUs, not sure if we need to run on both
-		 * cores.
-		 */
-		local_irq_save(flags);
-		clockevents_update_freq(&ttcce->ce,
-				ndata->new_rate / PRESCALE);
-		local_irq_restore(flags);
-
 		/* update cached frequency */
 		ttc->freq = ndata->new_rate;
 
+		clockevents_update_freq(&ttcce->ce, ndata->new_rate / PRESCALE);
+
 		/* fall through */
-	}
 	case PRE_RATE_CHANGE:
 	case ABORT_RATE_CHANGE:
 	default:
-- 
1.8.5.3

[PATCH v3 4/7] clocksource/cadence_ttc: Overhaul clocksource frequency adjustment

[Soren Brinkmann]

The currently used method adjusting the clocksource to a changing input
frequency does not work on kernels from 3.11 on.
The new approach is to keep the timer frequency as constant as possible.
I.e.
 - due to the TTC's prescaler limitations, allow frequency changes
   only if the frequency scales by a power of 2
 - adjust the counter's divider on the fly when a frequency change
   occurs

This limits cpufreq to scale by certain factors only.
But we may keep the time base somewhat constant, so that sleep() & co
keep working as expected, while supporting cpufreq.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
v3:
 - Clock notifier data does not behave as documented. Adjust code
   accordingly (https://lkml.org/lkml/2014/1/22/412)
v2:
 - remove PM notifier and associated code

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
 drivers/clocksource/cadence_ttc_timer.c | 104 ++++++++++++++++++++++++++------
 1 file changed, 84 insertions(+), 20 deletions(-)

diff --git a/drivers/clocksource/cadence_ttc_timer.c b/drivers/clocksource/cadence_ttc_timer.c
index f05b9fdc7425..49fbe2847c84 100644
--- a/drivers/clocksource/cadence_ttc_timer.c
+++ b/drivers/clocksource/cadence_ttc_timer.c
@@ -16,6 +16,7 @@
  */
 
 #include <linux/clk.h>
+#include <linux/clk-provider.h>
 #include <linux/interrupt.h>
 #include <linux/clockchips.h>
 #include <linux/of_address.h>
@@ -52,6 +53,8 @@
 #define TTC_CNT_CNTRL_DISABLE_MASK	0x1
 
 #define TTC_CLK_CNTRL_CSRC_MASK		(1 << 5)	/* clock source */
+#define TTC_CLK_CNTRL_PSV_MASK		0x1e
+#define TTC_CLK_CNTRL_PSV_SHIFT		1
 
 /*
  * Setup the timers to use pre-scaling, using a fixed value for now that will
@@ -63,6 +66,8 @@
 #define CLK_CNTRL_PRESCALE_EN	1
 #define CNT_CNTRL_RESET		(1 << 4)
 
+#define MAX_F_ERR 50
+
 /**
  * struct ttc_timer - This definition defines local timer structure
  *
@@ -82,6 +87,8 @@ struct ttc_timer {
 		container_of(x, struct ttc_timer, clk_rate_change_nb)
 
 struct ttc_timer_clocksource {
+	u32			scale_clk_ctrl_reg_old;
+	u32			scale_clk_ctrl_reg_new;
 	struct ttc_timer	ttc;
 	struct clocksource	cs;
 };
@@ -229,32 +236,89 @@ static int ttc_rate_change_clocksource_cb(struct notifier_block *nb,
 			struct ttc_timer_clocksource, ttc);
 
 	switch (event) {
-	case POST_RATE_CHANGE:
+	case PRE_RATE_CHANGE:
+	{
+		u32 psv;
+		unsigned long factor, rate_low, rate_high;
+
+		if (ndata->new_rate > ndata->old_rate) {
+			factor = DIV_ROUND_CLOSEST(ndata->new_rate,
+					ndata->old_rate);
+			rate_low = ndata->old_rate;
+			rate_high = ndata->new_rate;
+		} else {
+			factor = DIV_ROUND_CLOSEST(ndata->old_rate,
+					ndata->new_rate);
+			rate_low = ndata->new_rate;
+			rate_high = ndata->old_rate;
+		}
+
+		if (!is_power_of_2(factor))
+				return NOTIFY_BAD;
+
+		if (abs(rate_high - (factor * rate_low)) > MAX_F_ERR)
+			return NOTIFY_BAD;
+
+		factor = __ilog2_u32(factor);
+
 		/*
-		 * Do whatever is necessary to maintain a proper time base
-		 *
-		 * I cannot find a way to adjust the currently used clocksource
-		 * to the new frequency. __clocksource_updatefreq_hz() sounds
-		 * good, but does not work. Not sure what's that missing.
-		 *
-		 * This approach works, but triggers two clocksource switches.
-		 * The first after unregister to clocksource jiffies. And
-		 * another one after the register to the newly registered timer.
-		 *
-		 * Alternatively we could 'waste' another HW timer to ping pong
-		 * between clock sources. That would also use one register and
-		 * one unregister call, but only trigger one clocksource switch
-		 * for the cost of another HW timer used by the OS.
+		 * store timer clock ctrl register so we can restore it in case
+		 * of an abort.
 		 */
-		clocksource_unregister(&ttccs->cs);
-		clocksource_register_hz(&ttccs->cs,
-				ndata->new_rate / PRESCALE);
-		/* fall through */
-	case PRE_RATE_CHANGE:
+		ttccs->scale_clk_ctrl_reg_old =
+			__raw_readl(ttccs->ttc.base_addr +
+					TTC_CLK_CNTRL_OFFSET);
+
+		psv = (ttccs->scale_clk_ctrl_reg_old &
+				TTC_CLK_CNTRL_PSV_MASK) >>
+				TTC_CLK_CNTRL_PSV_SHIFT;
+		if (ndata->new_rate < ndata->old_rate)
+			psv -= factor;
+		else
+			psv += factor;
+
+		/* prescaler within legal range? */
+		if (psv & ~(TTC_CLK_CNTRL_PSV_MASK >> TTC_CLK_CNTRL_PSV_SHIFT))
+			return NOTIFY_BAD;
+
+		ttccs->scale_clk_ctrl_reg_new = ttccs->scale_clk_ctrl_reg_old &
+			~TTC_CLK_CNTRL_PSV_MASK;
+		ttccs->scale_clk_ctrl_reg_new |= psv << TTC_CLK_CNTRL_PSV_SHIFT;
+
+
+		/* scale down: adjust divider in post-change notification */
+		if (ndata->new_rate < ndata->old_rate)
+			return NOTIFY_DONE;
+
+		/* scale up: adjust divider now - before frequency change */
+		__raw_writel(ttccs->scale_clk_ctrl_reg_new,
+				ttccs->ttc.base_addr + TTC_CLK_CNTRL_OFFSET);
+		break;
+	}
+	case POST_RATE_CHANGE:
+		/* scale up: pre-change notification did the adjustment */
+		if (ndata->new_rate > ndata->old_rate)
+			return NOTIFY_OK;
+
+		/* scale down: adjust divider now - after frequency change */
+		__raw_writel(ttccs->scale_clk_ctrl_reg_new,
+				ttccs->ttc.base_addr + TTC_CLK_CNTRL_OFFSET);
+		break;
+
 	case ABORT_RATE_CHANGE:
+		/* we have to undo the adjustment in case we scale up */
+		if (ndata->new_rate < ndata->old_rate)
+			return NOTIFY_OK;
+
+		/* restore original register value */
+		__raw_writel(ttccs->scale_clk_ctrl_reg_old,
+				ttccs->ttc.base_addr + TTC_CLK_CNTRL_OFFSET);
+		/* fall through */
 	default:
 		return NOTIFY_DONE;
 	}
+
+	return NOTIFY_DONE;
 }
 
 static void __init ttc_setup_clocksource(struct clk *clk, void __iomem *base)
-- 
1.8.5.3

[PATCH v3 5/7] clocksource/cadence_ttc: Use only one counter

[Soren Brinkmann]

Currently the driver uses two of the three counters the TTC provides to
implement a clocksource and a clockevent device. By using the TTC's
match feature we can implement both use cases using a single counter
only.
The old approach is to use timer over-/underflow to generate an
interrupt. Using the match register allows to generate an interrupt on
arbitrary counter values. This way a dedicated clockevent counter can be
avoided.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
 drivers/clocksource/cadence_ttc_timer.c | 92 +++++++++++----------------------
 1 file changed, 31 insertions(+), 61 deletions(-)

diff --git a/drivers/clocksource/cadence_ttc_timer.c b/drivers/clocksource/cadence_ttc_timer.c
index 49fbe2847c84..d922e982af95 100644
--- a/drivers/clocksource/cadence_ttc_timer.c
+++ b/drivers/clocksource/cadence_ttc_timer.c
@@ -47,6 +47,7 @@
 #define TTC_CNT_CNTRL_OFFSET		0x0C /* Counter Control Reg, RW */
 #define TTC_COUNT_VAL_OFFSET		0x18 /* Counter Value Reg, RO */
 #define TTC_INTR_VAL_OFFSET		0x24 /* Interval Count Reg, RW */
+#define TTC_MATCH1_OFFSET	0x30 /* Match reg, RW */
 #define TTC_ISR_OFFSET		0x54 /* Interrupt Status Reg, RO */
 #define TTC_IER_OFFSET		0x60 /* Interrupt Enable Reg, RW */
 
@@ -64,7 +65,10 @@
 #define PRESCALE		2048	/* The exponent must match this */
 #define CLK_CNTRL_PRESCALE	((PRESCALE_EXPONENT - 1) << 1)
 #define CLK_CNTRL_PRESCALE_EN	1
-#define CNT_CNTRL_RESET		(1 << 4)
+#define CNT_CNTRL_RESET		BIT(4)
+#define CNT_CNTRL_MATCH		BIT(3)
+
+#define TTC_INTERRUPT_MATCH1	BIT(1)
 
 #define MAX_F_ERR 50
 
@@ -99,6 +103,7 @@ struct ttc_timer_clocksource {
 struct ttc_timer_clockevent {
 	struct ttc_timer		ttc;
 	struct clock_event_device	ce;
+	unsigned long			interval;
 };
 
 #define to_ttc_timer_clkevent(x) \
@@ -112,25 +117,20 @@ static void __iomem *ttc_sched_clock_val_reg;
  * @timer:	Pointer to the timer instance
  * @cycles:	Timer interval ticks
  **/
-static void ttc_set_interval(struct ttc_timer *timer,
-					unsigned long cycles)
+static void ttc_set_interval(struct ttc_timer *timer, unsigned long cycles)
 {
-	u32 ctrl_reg;
+	struct ttc_timer_clockevent *ttcce = container_of(timer,
+			struct ttc_timer_clockevent, ttc);
 
-	/* Disable the counter, set the counter value  and re-enable counter */
-	ctrl_reg = __raw_readl(timer->base_addr + TTC_CNT_CNTRL_OFFSET);
-	ctrl_reg |= TTC_CNT_CNTRL_DISABLE_MASK;
-	__raw_writel(ctrl_reg, timer->base_addr + TTC_CNT_CNTRL_OFFSET);
+	/* set interval */
+	u32 reg = __raw_readl(timer->base_addr + TTC_COUNT_VAL_OFFSET);
+	reg += cycles;
+	__raw_writel(reg, timer->base_addr + TTC_MATCH1_OFFSET);
 
-	__raw_writel(cycles, timer->base_addr + TTC_INTR_VAL_OFFSET);
+	/* enable match interrupt */
+	__raw_writel(TTC_INTERRUPT_MATCH1, timer->base_addr + TTC_IER_OFFSET);
 
-	/*
-	 * Reset the counter (0x10) so that it starts from 0, one-shot
-	 * mode makes this needed for timing to be right.
-	 */
-	ctrl_reg |= CNT_CNTRL_RESET;
-	ctrl_reg &= ~TTC_CNT_CNTRL_DISABLE_MASK;
-	__raw_writel(ctrl_reg, timer->base_addr + TTC_CNT_CNTRL_OFFSET);
+	ttcce->interval = cycles;
 }
 
 /**
@@ -148,6 +148,8 @@ static irqreturn_t ttc_clock_event_interrupt(int irq, void *dev_id)
 
 	/* Acknowledge the interrupt and call event handler */
 	__raw_readl(timer->base_addr + TTC_ISR_OFFSET);
+	if (ttce->ce.mode == CLOCK_EVT_MODE_PERIODIC)
+		ttc_set_interval(timer, ttce->interval);
 
 	ttce->ce.event_handler(&ttce->ce);
 
@@ -201,7 +203,6 @@ static void ttc_set_mode(enum clock_event_mode mode,
 {
 	struct ttc_timer_clockevent *ttce = to_ttc_timer_clkevent(evt);
 	struct ttc_timer *timer = &ttce->ttc;
-	u32 ctrl_reg;
 
 	switch (mode) {
 	case CLOCK_EVT_MODE_PERIODIC:
@@ -211,18 +212,9 @@ static void ttc_set_mode(enum clock_event_mode mode,
 	case CLOCK_EVT_MODE_ONESHOT:
 	case CLOCK_EVT_MODE_UNUSED:
 	case CLOCK_EVT_MODE_SHUTDOWN:
-		ctrl_reg = __raw_readl(timer->base_addr +
-					TTC_CNT_CNTRL_OFFSET);
-		ctrl_reg |= TTC_CNT_CNTRL_DISABLE_MASK;
-		__raw_writel(ctrl_reg,
-				timer->base_addr + TTC_CNT_CNTRL_OFFSET);
+		__raw_writel(0, timer->base_addr + TTC_IER_OFFSET);
 		break;
 	case CLOCK_EVT_MODE_RESUME:
-		ctrl_reg = __raw_readl(timer->base_addr +
-					TTC_CNT_CNTRL_OFFSET);
-		ctrl_reg &= ~TTC_CNT_CNTRL_DISABLE_MASK;
-		__raw_writel(ctrl_reg,
-				timer->base_addr + TTC_CNT_CNTRL_OFFSET);
 		break;
 	}
 }
@@ -354,17 +346,6 @@ static void __init ttc_setup_clocksource(struct clk *clk, void __iomem *base)
 	ttccs->cs.mask = CLOCKSOURCE_MASK(16);
 	ttccs->cs.flags = CLOCK_SOURCE_IS_CONTINUOUS;
 
-	/*
-	 * Setup the clock source counter to be an incrementing counter
-	 * with no interrupt and it rolls over at 0xFFFF. Pre-scale
-	 * it by 32 also. Let it start running now.
-	 */
-	__raw_writel(0x0,  ttccs->ttc.base_addr + TTC_IER_OFFSET);
-	__raw_writel(CLK_CNTRL_PRESCALE | CLK_CNTRL_PRESCALE_EN,
-		     ttccs->ttc.base_addr + TTC_CLK_CNTRL_OFFSET);
-	__raw_writel(CNT_CNTRL_RESET,
-		     ttccs->ttc.base_addr + TTC_CNT_CNTRL_OFFSET);
-
 	err = clocksource_register_hz(&ttccs->cs, ttccs->ttc.freq / PRESCALE);
 	if (WARN_ON(err)) {
 		kfree(ttccs);
@@ -433,16 +414,6 @@ static void __init ttc_setup_clockevent(struct clk *clk,
 	ttcce->ce.irq = irq;
 	ttcce->ce.cpumask = cpu_possible_mask;
 
-	/*
-	 * Setup the clock event timer to be an interval timer which
-	 * is prescaled by 32 using the interval interrupt. Leave it
-	 * disabled for now.
-	 */
-	__raw_writel(0x23, ttcce->ttc.base_addr + TTC_CNT_CNTRL_OFFSET);
-	__raw_writel(CLK_CNTRL_PRESCALE | CLK_CNTRL_PRESCALE_EN,
-		     ttcce->ttc.base_addr + TTC_CLK_CNTRL_OFFSET);
-	__raw_writel(0x1,  ttcce->ttc.base_addr + TTC_IER_OFFSET);
-
 	err = request_irq(irq, ttc_clock_event_interrupt,
 			  IRQF_TIMER, ttcce->ce.name, ttcce);
 	if (WARN_ON(err)) {
@@ -464,7 +435,7 @@ static void __init ttc_timer_init(struct device_node *timer)
 {
 	unsigned int irq;
 	void __iomem *timer_baseaddr;
-	struct clk *clk_cs, *clk_ce;
+	struct clk *clk;
 	static int initialized;
 	int clksel;
 
@@ -484,7 +455,7 @@ static void __init ttc_timer_init(struct device_node *timer)
 		BUG();
 	}
 
-	irq = irq_of_parse_and_map(timer, 1);
+	irq = irq_of_parse_and_map(timer, 0);
 	if (irq <= 0) {
 		pr_err("ERROR: invalid interrupt number\n");
 		BUG();
@@ -492,22 +463,21 @@ static void __init ttc_timer_init(struct device_node *timer)
 
 	clksel = __raw_readl(timer_baseaddr + TTC_CLK_CNTRL_OFFSET);
 	clksel = !!(clksel & TTC_CLK_CNTRL_CSRC_MASK);
-	clk_cs = of_clk_get(timer, clksel);
-	if (IS_ERR(clk_cs)) {
+	clk = of_clk_get(timer, clksel);
+	if (IS_ERR(clk)) {
 		pr_err("ERROR: timer input clock not found\n");
 		BUG();
 	}
 
-	clksel = __raw_readl(timer_baseaddr + 4 + TTC_CLK_CNTRL_OFFSET);
-	clksel = !!(clksel & TTC_CLK_CNTRL_CSRC_MASK);
-	clk_ce = of_clk_get(timer, clksel);
-	if (IS_ERR(clk_ce)) {
-		pr_err("ERROR: timer input clock not found\n");
-		BUG();
-	}
+	__raw_writel(CLK_CNTRL_PRESCALE | CLK_CNTRL_PRESCALE_EN,
+			timer_baseaddr + TTC_CLK_CNTRL_OFFSET);
+
+	/* start timer in overflow and match mode */
+	__raw_writel(CNT_CNTRL_RESET | CNT_CNTRL_MATCH,
+			timer_baseaddr + TTC_CNT_CNTRL_OFFSET);
 
-	ttc_setup_clocksource(clk_cs, timer_baseaddr);
-	ttc_setup_clockevent(clk_ce, timer_baseaddr + 4, irq);
+	ttc_setup_clocksource(clk, timer_baseaddr);
+	ttc_setup_clockevent(clk, timer_baseaddr, irq);
 
 	pr_info("%s #0 at %p, irq=%d\n", timer->name, timer_baseaddr, irq);
 }
-- 
1.8.5.3

Re: [PATCH v3 5/7] clocksource/cadence_ttc: Use only one counter

[Thomas Gleixner]

On Mon, 3 Feb 2014, Soren Brinkmann wrote:

> Currently the driver uses two of the three counters the TTC provides to
> implement a clocksource and a clockevent device. By using the TTC's
> match feature we can implement both use cases using a single counter
> only.

Are you entirely sure that this match feature is free of the infamous
HPET match feature issues?

See arch/x86/kernel/hpet.c: hpet_next_event()

If yes, please add a comment. If no ....

Thanks,

	tglx

Re: [PATCH v3 5/7] clocksource/cadence_ttc: Use only one counter

[Sören Brinkmann]

Hi Thomas,

On Tue, Feb 04, 2014 at 09:41:53PM +0100, Thomas Gleixner wrote:
> On Mon, 3 Feb 2014, Soren Brinkmann wrote:
> 
> > Currently the driver uses two of the three counters the TTC provides to
> > implement a clocksource and a clockevent device. By using the TTC's
> > match feature we can implement both use cases using a single counter
> > only.
> 
> Are you entirely sure that this match feature is free of the infamous
> HPET match feature issues?
> 
> See arch/x86/kernel/hpet.c: hpet_next_event()
> 
> If yes, please add a comment. If no ....
Good catch. Looks like the comparator compares on == as well. So, I
assume it may show similar issues. I'll have to spend some more time
looking into this.

Thanks for applying the first two patches of the series.

	Thanks,
	Sören

[PATCH v3 6/7] arm: zynq: Don't use arm_global_timer with cpufreq

[Soren Brinkmann]

The timer frequency of the arm_global_timer depends on the CPU
frequency. With cpufreq altering that frequency the arm_global_timer
does not maintain a stable time base. Therefore don't enable that timer
in case cpufreq is enabled.

Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
 arch/arm/mach-zynq/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/mach-zynq/Kconfig b/arch/arm/mach-zynq/Kconfig
index 6b04260aa142..f84fab14f0b7 100644
--- a/arch/arm/mach-zynq/Kconfig
+++ b/arch/arm/mach-zynq/Kconfig
@@ -13,6 +13,6 @@ config ARCH_ZYNQ
 	select HAVE_SMP
 	select SPARSE_IRQ
 	select CADENCE_TTC_TIMER
-	select ARM_GLOBAL_TIMER
+	select ARM_GLOBAL_TIMER if !CPU_FREQ
 	help
 	  Support for Xilinx Zynq ARM Cortex A9 Platform
-- 
1.8.5.3

[PATCH v3 7/7] arm: zynq: Add support for cpufreq

[Soren Brinkmann]

The generic cpufreq-cpu0 driver can scale the CPU frequency on Zynq
SOCs. Add the required platform device to the BSP and appropriate
OPPs to the dts.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
Cc: Kumar Gala <galak@codeaurora.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: devicetree@vger.kernel.org
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
v3:
 - change lowest frequency to 222223 (F_max / 3)
---
 arch/arm/boot/dts/zynq-7000.dtsi | 6 ++++++
 arch/arm/mach-zynq/Kconfig       | 2 ++
 arch/arm/mach-zynq/common.c      | 3 +++
 3 files changed, 11 insertions(+)

diff --git a/arch/arm/boot/dts/zynq-7000.dtsi b/arch/arm/boot/dts/zynq-7000.dtsi
index 8b67b19392ec..789d0bacc110 100644
--- a/arch/arm/boot/dts/zynq-7000.dtsi
+++ b/arch/arm/boot/dts/zynq-7000.dtsi
@@ -24,6 +24,12 @@
 			device_type = "cpu";
 			reg = <0>;
 			clocks = <&clkc 3>;
+			operating-points = <
+				/* kHz    uV */
+				666667  1000000
+				333334  1000000
+				222223  1000000
+			>;
 		};
 
 		cpu@1 {
diff --git a/arch/arm/mach-zynq/Kconfig b/arch/arm/mach-zynq/Kconfig
index f84fab14f0b7..f03e75bd0b2b 100644
--- a/arch/arm/mach-zynq/Kconfig
+++ b/arch/arm/mach-zynq/Kconfig
@@ -2,6 +2,8 @@ config ARCH_ZYNQ
 	bool "Xilinx Zynq ARM Cortex A9 Platform" if ARCH_MULTI_V7
 	select ARM_AMBA
 	select ARM_GIC
+	select ARCH_HAS_CPUFREQ
+	select ARCH_HAS_OPP
 	select COMMON_CLK
 	select CPU_V7
 	select GENERIC_CLOCKEVENTS
diff --git a/arch/arm/mach-zynq/common.c b/arch/arm/mach-zynq/common.c
index 1db2a5ca9ab8..644468151c04 100644
--- a/arch/arm/mach-zynq/common.c
+++ b/arch/arm/mach-zynq/common.c
@@ -51,6 +51,8 @@ static struct platform_device zynq_cpuidle_device = {
  */
 static void __init zynq_init_machine(void)
 {
+	struct platform_device_info devinfo = { .name = "cpufreq-cpu0", };
+
 	/*
 	 * 64KB way size, 8-way associativity, parity disabled
 	 */
@@ -59,6 +61,7 @@ static void __init zynq_init_machine(void)
 	of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
 
 	platform_device_register(&zynq_cpuidle_device);
+	platform_device_register_full(&devinfo);
 }
 
 static void __init zynq_timer_init(void)
-- 
1.8.5.3