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[PATCH 0/9] ARC clockevent/clocksource modernization

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  [PATCH 0/9] ARC clockevent/clocksource modernization Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-02 12:00 +0100
    [PATCH 2/9] ARC: [dts] Introduce Timer bindings Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-02 12:00 +0100
      Re: [PATCH 2/9] ARC: [dts] Introduce Timer bindings Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2016-02-02 13:50 +0100
      Re: [PATCH 2/9] ARC: [dts] Introduce Timer bindings Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2016-02-02 14:20 +0100
        Re: [PATCH 2/9] ARC: [dts] Introduce Timer bindings Vineet Gupta <vgupta@synopsys.com> - 2016-02-02 15:30 +0100
          Re: [PATCH 2/9] ARC: [dts] Introduce Timer bindings Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2016-02-02 16:40 +0100
            Re: [PATCH 2/9] ARC: [dts] Introduce Timer bindings Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2016-02-03 00:00 +0100
              Re: [PATCH 2/9] ARC: [dts] Introduce Timer bindings Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2016-02-03 14:50 +0100
                Re: [PATCH 2/9] ARC: [dts] Introduce Timer bindings Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2016-02-03 15:00 +0100
      Re: [PATCH 2/9] ARC: [dts] Introduce Timer bindings Rob Herring <robh@kernel.org> - 2016-02-02 23:10 +0100
        Re: [PATCH 2/9] ARC: [dts] Introduce Timer bindings Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-03 09:10 +0100
          Re: [PATCH 2/9] ARC: [dts] Introduce Timer bindings Rob Herring <robh@kernel.org> - 2016-02-03 16:40 +0100
    [PATCH 6/9] ARC: clocksource: DT based probe Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-02 12:10 +0100
      Re: [PATCH 6/9] ARC: clocksource: DT based probe Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-02-08 13:20 +0100
        Re: [PATCH 6/9] ARC: clocksource: DT based probe Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-08 13:30 +0100
    [PATCH 3/9] ARC: clockevent: switch to cpu notifier for clockevent setup Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-02 12:10 +0100
    [PATCH 9/9] ARC: RIP arc_{get|set}_core_freq() clk API Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-02 12:10 +0100
    [PATCH 4/9] ARC: clockevent: Prepare for DT based probe Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-02 12:10 +0100
    [PATCH 7/9] ARC: use fixed frequencies in arc_set_early_base_baud() Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-02 12:10 +0100
      Re: [PATCH 7/9] ARC: use fixed frequencies in  arc_set_early_base_baud() Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2016-02-02 14:00 +0100
        Re: [PATCH 7/9] ARC: use fixed frequencies in arc_set_early_base_baud() christian.ruppert@alitech.com - 2016-02-02 15:10 +0100
          Re: [PATCH 7/9] ARC: use fixed frequencies in  arc_set_early_base_baud() Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2016-02-02 15:30 +0100
    [PATCH 5/9] ARC: clockevent: DT based probe Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-02 12:10 +0100
    [PATCH 8/9] ARC: [plat-axs] Don't use arc_{get|set}_core_freq() for manipulating core clk Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-02-02 12:10 +0100

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#1324107 — Re: [PATCH 7/9] ARC: use fixed frequencies in arc_set_early_base_baud()

Alexey Brodkin <Alexey.Brodkin@synopsys.com> wrote on 02.02.2016 13:53:26:
> 
> Adding Christian for Abilis TB10x clocks review.
> 
> On Tue, 2016-02-02 at 16:28 +0530, Vineet Gupta wrote:
> > From: Alexey Brodkin <abrodkin@synopsys.com>
> > 
> > UARTs usually have fixed clock so we're switching to use of
> > constant values instead of something derived from core clock
> > frequency.
> > 
> > Among other things this will allow us to get rid of
> > arc_{get|set}_core_freq() and switch to generic clock
> > framework later on.
> > 
> > Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
> > Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
> > ---
> >  arch/arc/kernel/devtree.c | 6 ++----
> >  1 file changed, 2 insertions(+), 4 deletions(-)
> > 
> > diff --git a/arch/arc/kernel/devtree.c b/arch/arc/kernel/devtree.c
> > index 7e844fd8213f..e155126c79b1 100644
> > --- a/arch/arc/kernel/devtree.c
> > +++ b/arch/arc/kernel/devtree.c
> > @@ -28,14 +28,12 @@ unsigned int __init arc_early_base_baud(void)
> > 
> >  static void __init arc_set_early_base_baud(unsigned long dt_root)
> >  {
> > -   unsigned int core_clk = arc_get_core_freq();
> > -
> >     if (of_flat_dt_is_compatible(dt_root, "abilis,arc-tb10x"))
> > -      arc_base_baud = core_clk/3;
> > +      arc_base_baud = 166666667;   /* Fixed 166.7MHz clk (TB10x) */

Actually, (int)core_clk/(int)3 is 166666666 not 166666667.
I seem to remember that this rounding detail did make a difference at some 
point. Unluckily, the details are long forgotten in the mist of time...

> >     else if (of_flat_dt_is_compatible(dt_root, "snps,arc-sdp"))
> >        arc_base_baud = 33333333;   /* Fixed 33MHz clk (AXS10x) */
> >     else
> > -      arc_base_baud = core_clk;
> > +      arc_base_baud = 50000000;   /* Fixed default 50MHz */
> >  }
> >  #else
> >  #define arc_set_early_base_baud(dt_root)
> 
> -Alexey

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#1324125 — Re: [PATCH 7/9] ARC: use fixed frequencies in arc_set_early_base_baud()

Hi Christian,

On Tue, 2016-02-02 at 14:43 +0100, christian.ruppert@alitech.com wrote:
> Alexey Brodkin <Alexey.Brodkin@synopsys.com> wrote on 02.02.2016 13:53:26:
> > 
> > Adding Christian for Abilis TB10x clocks review.
> > 
> > On Tue, 2016-02-02 at 16:28 +0530, Vineet Gupta wrote:
> > > From: Alexey Brodkin <abrodkin@synopsys.com>
> > > 
> > > UARTs usually have fixed clock so we're switching to use of
> > > constant values instead of something derived from core clock
> > > frequency.
> > > 
> > > Among other things this will allow us to get rid of
> > > arc_{get|set}_core_freq() and switch to generic clock
> > > framework later on.
> > > 
> > > Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
> > > Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
> > > ---
> > >  arch/arc/kernel/devtree.c | 6 ++----
> > >  1 file changed, 2 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/arch/arc/kernel/devtree.c b/arch/arc/kernel/devtree.c
> > > index 7e844fd8213f..e155126c79b1 100644
> > > --- a/arch/arc/kernel/devtree.c
> > > +++ b/arch/arc/kernel/devtree.c
> > > @@ -28,14 +28,12 @@ unsigned int __init arc_early_base_baud(void)
> > > 
> > >  static void __init arc_set_early_base_baud(unsigned long dt_root)
> > >  {
> > > -   unsigned int core_clk = arc_get_core_freq();
> > > -
> > >     if (of_flat_dt_is_compatible(dt_root, "abilis,arc-tb10x"))
> > > -      arc_base_baud = core_clk/3;
> > > +      arc_base_baud = 166666667;   /* Fixed 166.7MHz clk (TB10x) */
> 
> Actually, (int)core_clk/(int)3 is 166666666 not 166666667.
> I seem to remember that this rounding detail did make a difference at some 
> point. Unluckily, the details are long forgotten in the mist of time...

Interesting :)

I did that rounding intentionally hoping for the best.
But so good we've got your valuable input before it's too late.

-Alexey

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#1323982 — [PATCH 5/9] ARC: clockevent: DT based probe

 - timer frequency is derived from DT (no longer rely on top level
   DT "clock-frequency" probed early and exported by asm/clk.h)

 - TIMER0_IRQ need not be exported across arch code, confided to intc as
   it is property of same

Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/include/asm/irq.h     |  4 ---
 arch/arc/kernel/intc-compact.c |  2 ++
 arch/arc/kernel/time.c         | 67 ++++++++++++++++++++++++++----------------
 3 files changed, 44 insertions(+), 29 deletions(-)

diff --git a/arch/arc/include/asm/irq.h b/arch/arc/include/asm/irq.h
index 0c86f0787bcd..44b6ea85e8fb 100644
--- a/arch/arc/include/asm/irq.h
+++ b/arch/arc/include/asm/irq.h
@@ -14,12 +14,8 @@
 
 /* Platform Independent IRQs */
 #ifdef CONFIG_ISA_ARCOMPACT
-#define TIMER0_IRQ      3
-#define TIMER1_IRQ      4
 #define IPI_IRQ		(NR_CPU_IRQS-1) /* dummy to enable SMP build for up hardware */
 #else
-#define TIMER0_IRQ      16
-#define TIMER1_IRQ      17
 #define IPI_IRQ         19
 #endif
 
diff --git a/arch/arc/kernel/intc-compact.c b/arch/arc/kernel/intc-compact.c
index 06bcedf19b62..5d390958d233 100644
--- a/arch/arc/kernel/intc-compact.c
+++ b/arch/arc/kernel/intc-compact.c
@@ -14,6 +14,8 @@
 #include <linux/irqchip.h>
 #include <asm/irq.h>
 
+#define TIMER0_IRQ	3	/* Fixed by ISA */
+
 /*
  * Early Hardware specific Interrupt setup
  * -Platform independent, needed for each CPU (not foldable into init_IRQ)
diff --git a/arch/arc/kernel/time.c b/arch/arc/kernel/time.c
index 1f5a6fe03bcc..43ef22853473 100644
--- a/arch/arc/kernel/time.c
+++ b/arch/arc/kernel/time.c
@@ -29,22 +29,16 @@
  * which however is currently broken
  */
 
-#include <linux/spinlock.h>
 #include <linux/interrupt.h>
-#include <linux/module.h>
-#include <linux/sched.h>
-#include <linux/kernel.h>
-#include <linux/time.h>
-#include <linux/init.h>
-#include <linux/timex.h>
-#include <linux/profile.h>
 #include <linux/clk-provider.h>
+#include <linux/clk.h>
 #include <linux/clocksource.h>
 #include <linux/clockchips.h>
+#include <linux/cpu.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
 #include <asm/irq.h>
 #include <asm/arcregs.h>
-#include <asm/clk.h>
-#include <asm/mach_desc.h>
 
 #include <asm/mcip.h>
 
@@ -61,6 +55,24 @@
 
 #define ARC_TIMER_MAX	0xFFFFFFFF
 
+static unsigned long arc_timer_freq;
+
+static void noinline arc_get_timer_clk(struct device_node *node)
+{
+	struct clk *clk;
+	int ret;
+
+	clk = of_clk_get(node, 0);
+	if (IS_ERR(clk))
+		panic("Can't get timer clock");
+
+	ret = clk_prepare_enable(clk);
+	if (ret)
+		pr_err("Couldn't enable parent clock\n");
+
+	arc_timer_freq = clk_get_rate(clk);
+}
+
 /********** Clock Source Device *********/
 
 #ifdef CONFIG_ARC_HAS_GFRC
@@ -184,7 +196,7 @@ static struct clocksource arc_counter = {
 
 /********** Clock Event Device *********/
 
-static int arc_timer_irq = TIMER0_IRQ;
+static int arc_timer_irq;
 
 /*
  * Arm the timer to interrupt after @cycles
@@ -212,7 +224,7 @@ static int arc_clkevent_set_periodic(struct clock_event_device *dev)
 	 * At X Hz, 1 sec = 1000ms -> X cycles;
 	 *		      10ms -> X / 100 cycles
 	 */
-	arc_timer_event_setup(arc_get_core_freq() / HZ);
+	arc_timer_event_setup(arc_timer_freq / HZ);
 	return 0;
 }
 
@@ -221,7 +233,6 @@ static DEFINE_PER_CPU(struct clock_event_device, arc_clockevent_device) = {
 	.features		= CLOCK_EVT_FEAT_ONESHOT |
 				  CLOCK_EVT_FEAT_PERIODIC,
 	.rating			= 300,
-	.irq			= TIMER0_IRQ,	/* hardwired, no need for resources */
 	.set_next_event		= arc_clkevent_set_next_event,
 	.set_state_periodic	= arc_clkevent_set_periodic,
 };
@@ -256,7 +267,7 @@ static int arc_timer_cpu_notify(struct notifier_block *self,
 
 	switch (action & ~CPU_TASKS_FROZEN) {
 	case CPU_STARTING:
-		clockevents_config_and_register(evt, arc_get_core_freq(),
+		clockevents_config_and_register(evt, arc_timer_freq,
 						0, ULONG_MAX);
 		enable_percpu_irq(arc_timer_irq, 0);
 		break;
@@ -268,32 +279,41 @@ static int arc_timer_cpu_notify(struct notifier_block *self,
 	return NOTIFY_OK;
 }
 
-static struct notifier_block nps_timer_cpu_nb = {
+static struct notifier_block arc_timer_cpu_nb = {
 	.notifier_call = arc_timer_cpu_notify,
 };
 
 /*
  * clockevent setup for boot CPU
  */
-static void __init arc_clockevent_setup()
+static void __init arc_clockevent_setup(struct device_node *node)
 {
 	struct clock_event_device *evt = this_cpu_ptr(&arc_clockevent_device);
+	int ret;
 
 	register_cpu_notifier(&arc_timer_cpu_nb);
 
+	arc_timer_irq = irq_of_parse_and_map(node, 0);
+	if (arc_timer_irq <= 0)
+		panic("Can't parse IRQ");
+
+	arc_get_timer_clk(node);
+
+	evt->irq = arc_timer_irq;
 	evt->cpumask = cpumask_of(smp_processor_id());
-	clockevents_config_and_register(evt, arc_get_core_freq(),
+	clockevents_config_and_register(evt, arc_timer_freq,
 					0, ARC_TIMER_MAX);
 
 	/* setup the per-cpu timer IRQ handler - for all cpus */
-	request_percpu_irq(arc_timer_irq, timer_irq_handler,
-			   "Timer0 (per-cpu-tick)", evt);
+	ret = request_percpu_irq(arc_timer_irq, timer_irq_handler,
+				 "Timer0 (per-cpu-tick)", evt);
+	if (ret)
+		pr_err("Unable to register interrupt\n");
 
 	enable_percpu_irq(arc_timer_irq, 0);
 
-	if (ret)
-		pr_err("Unable to register interrupt\n");
 }
+CLOCKSOURCE_OF_DECLARE(arc_clkevt, "snps,arc-timer0", arc_clockevent_setup);
 
 /*
  * Called from start_kernel() - boot CPU only
@@ -302,7 +322,6 @@ static void __init arc_clockevent_setup()
  * -Also sets up any global state needed for timer subsystem:
  *    - for "counting" timer, registers a clocksource, usable across CPUs
  *      (provided that underlying counter h/w is synchronized across cores)
- *    - for "event" timer, sets up TIMER0 IRQ (as that is platform agnostic)
  */
 void __init time_init(void)
 {
@@ -318,7 +337,5 @@ void __init time_init(void)
 		 * CLK upto 4.29 GHz can be safely represented in 32 bits
 		 * because Max 32 bit number is 4,294,967,295
 		 */
-		clocksource_register_hz(&arc_counter, arc_get_core_freq());
-
-	arc_clockevent_setup();
+		clocksource_register_hz(&arc_counter, arc_timer_freq);
 }
-- 
2.5.0

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#1323983 — [PATCH 8/9] ARC: [plat-axs] Don't use arc_{get|set}_core_freq() for manipulating core clk

From: Alexey Brodkin <abrodkin@synopsys.com>

For AXS103, certain bitfile configurations may not work with stock
"clock-frequency" specified in DT. Instead of duplicating the DT files, we
fixup the DT in-place.

This used to be done differently - as in top level "clock-frequency" was
read very early from FDT and exported using arc_{get|set}_core_freq()
also used in setting up clockevent/clocksource timers

This homebrew clk API served well for legacy timer probe (non DT)

However TIMERS are now probed from DT and use "core_clk" defined in DT,
and thus can no longer use the top level "clock-frequency".
This change reduces the number of users of ARC clk hack and paves way
for removal.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
[vgupta: broken out of from bigger patch]
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/kernel/setup.c       | 12 +++++++-----
 arch/arc/plat-axs10x/axs10x.c | 27 +++++++++++++++++++++------
 2 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c
index 953068e9c9e1..c35552dca46a 100644
--- a/arch/arc/kernel/setup.c
+++ b/arch/arc/kernel/setup.c
@@ -24,7 +24,6 @@
 #include <asm/page.h>
 #include <asm/irq.h>
 #include <asm/unwind.h>
-#include <asm/clk.h>
 #include <asm/mach_desc.h>
 #include <asm/smp.h>
 
@@ -208,10 +207,6 @@ static char *arc_cpu_mumbojumbo(int cpu_id, char *buf, int len)
 	if (tbl->info.id == 0)
 		n += scnprintf(buf + n, len - n, "UNKNOWN ARC Processor\n");
 
-	n += scnprintf(buf + n, len - n, "CPU speed\t: %u.%02u Mhz\n",
-		       (unsigned int)(arc_get_core_freq() / 1000000),
-		       (unsigned int)(arc_get_core_freq() / 10000) % 100);
-
 	n += scnprintf(buf + n, len - n, "Timers\t\t: %s%s%s%s\nISA Extn\t: ",
 		       IS_AVAIL1(cpu->extn.timer0, "Timer0 "),
 		       IS_AVAIL1(cpu->extn.timer1, "Timer1 "),
@@ -467,6 +462,10 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 {
 	char *str;
 	int cpu_id = ptr_to_cpu(v);
+	struct device_node *pll = of_find_node_by_name(NULL, "core_clk");
+	u32 freq;
+
+	of_property_read_u32(pll, "clock-frequency", &freq);
 
 	if (!cpu_online(cpu_id)) {
 		seq_printf(m, "processor [%d]\t: Offline\n", cpu_id);
@@ -478,6 +477,9 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 		goto done;
 
 	seq_printf(m, arc_cpu_mumbojumbo(cpu_id, str, PAGE_SIZE));
+	seq_printf(m, "CPU speed\t: %u.%02u Mhz\n",
+		   (unsigned int)(freq / 1000000),
+		   (unsigned int)(freq / 10000) % 100);
 
 	seq_printf(m, "Bogo MIPS\t: %lu.%02lu\n",
 		   loops_per_jiffy / (500000 / HZ),
diff --git a/arch/arc/plat-axs10x/axs10x.c b/arch/arc/plat-axs10x/axs10x.c
index 1b0f0f458a2b..9701c93f315d 100644
--- a/arch/arc/plat-axs10x/axs10x.c
+++ b/arch/arc/plat-axs10x/axs10x.c
@@ -14,10 +14,11 @@
  *
  */
 
+#include <linux/of_fdt.h>
 #include <linux/of_platform.h>
+#include <linux/libfdt.h>
 
 #include <asm/asm-offsets.h>
-#include <asm/clk.h>
 #include <asm/io.h>
 #include <asm/mach_desc.h>
 #include <asm/mcip.h>
@@ -389,6 +390,13 @@ axs103_set_freq(unsigned int id, unsigned int fd, unsigned int od)
 
 static void __init axs103_early_init(void)
 {
+	int offset = fdt_path_offset(initial_boot_params, "/cpu_card/core_clk");
+	const struct fdt_property *prop = fdt_get_property(initial_boot_params,
+							   offset,
+							   "clock-frequency",
+							   NULL);
+	u32 freq = be32_to_cpu(*(u32*)(prop->data)) / 1000000, orig = freq;
+
 	/*
 	 * AXS103 configurations for SMP/QUAD configurations share device tree
 	 * which defaults to 90 MHz. However recent failures of Quad config
@@ -401,12 +409,12 @@ static void __init axs103_early_init(void)
 #ifdef CONFIG_ARC_MCIP
 	unsigned int num_cores = (read_aux_reg(ARC_REG_MCIP_BCR) >> 16) & 0x3F;
 	if (num_cores > 2)
-		arc_set_core_freq(50 * 1000000);
+		freq = 50;
 	else if (num_cores == 2)
-		arc_set_core_freq(75 * 1000000);
+		freq = 75;
 #endif
 
-	switch (arc_get_core_freq()/1000000) {
+	switch (freq) {
 	case 33:
 		axs103_set_freq(1, 1, 1);
 		break;
@@ -431,11 +439,18 @@ static void __init axs103_early_init(void)
 		 * DT "clock-frequency" might not match with board value.
 		 * Hence update it to match the board value.
 		 */
-		arc_set_core_freq(axs103_get_freq() * 1000000);
+		freq = axs103_get_freq();
 		break;
 	}
 
-	pr_info("Freq is %dMHz\n", axs103_get_freq());
+	pr_info("Freq is %dMHz\n", freq);
+
+	/* Patching .dtb in-place with new core clock value */
+	if (freq != orig ) {
+		freq = cpu_to_be32(freq * 1000000);
+		fdt_setprop_inplace(initial_boot_params, offset,
+				    "clock-frequency", &freq, sizeof(freq));
+	}
 
 	/* Memory maps already config in pre-bootloader */
 
-- 
2.5.0

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