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[PATCH v3 0/4] ARM: at91: Properly handle slow clock

Started byAlexandre Belloni <alexandre.belloni@free-electrons.com>
First post2015-08-11 12:00 +0200
Last post2015-08-11 15:30 +0200
Articles 5 — 2 participants

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  [PATCH v3 0/4] ARM: at91: Properly handle slow clock Alexandre Belloni <alexandre.belloni@free-electrons.com> - 2015-08-11 12:00 +0200
    [PATCH v3 3/4] clocksource: tcb_clksrc: fix setup_clkevents error path Alexandre Belloni <alexandre.belloni@free-electrons.com> - 2015-08-11 12:00 +0200
      Re: [PATCH v3 3/4] clocksource: tcb_clksrc: fix setup_clkevents error  path Daniel Lezcano <daniel.lezcano@linaro.org> - 2015-08-11 15:30 +0200
    [PATCH v3 2/4] clocksource: atmel-st: get and use slow clock Alexandre Belloni <alexandre.belloni@free-electrons.com> - 2015-08-11 12:00 +0200
      Re: [PATCH v3 2/4] clocksource: atmel-st: get and use slow clock Daniel Lezcano <daniel.lezcano@linaro.org> - 2015-08-11 15:30 +0200

#1204975 — [PATCH v3 0/4] ARM: at91: Properly handle slow clock

FromAlexandre Belloni <alexandre.belloni@free-electrons.com>
Date2015-08-11 12:00 +0200
Subject[PATCH v3 0/4] ARM: at91: Properly handle slow clock
Message-ID<pWevE-1vq-3@gated-at.bofh.it>
Hi,

It was discovered that all the slow clock user were not properly claiming it.
This can end up in a system hang because the last registered user is releasing
it, and it gets disabled.

commit dca1a4b5ff6e ("clk: at91: keep slow clk enabled to prevent system hang")
was a workaround. This series is adding the slow clock to the necessary drivers
to avoid the issue and then removes that workaround.

Changes in v3:
 - dropped patches that were already taken or submitted separately
 - sclk is not a global anymore in timer-atmel-st.c
 - added Greg's ack

Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: linux-pwm@vger.kernel.org
Cc: linux-watchdog@vger.kernel.org
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wim Van Sebroeck <wim@iguana.be>

Alexandre Belloni (2):
  watchdog: at91sam9: get and use slow clock
  clocksource: atmel-st: get and use slow clock

Boris Brezillon (2):
  clocksource: tcb_clksrc: fix setup_clkevents error path
  misc: atmel_tclib: get and use slow clock

 drivers/clocksource/tcb_clksrc.c     | 10 +++++++++-
 drivers/clocksource/timer-atmel-st.c | 31 ++++++++++++++++++++++---------
 drivers/misc/atmel_tclib.c           |  4 ++++
 drivers/pwm/pwm-atmel-tcb.c          | 23 ++++++++++++++++-------
 drivers/watchdog/at91sam9_wdt.c      | 22 ++++++++++++++++++++--
 include/linux/atmel_tc.h             |  1 +
 6 files changed, 72 insertions(+), 19 deletions(-)

-- 
2.1.4

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#1204983 — [PATCH v3 3/4] clocksource: tcb_clksrc: fix setup_clkevents error path

FromAlexandre Belloni <alexandre.belloni@free-electrons.com>
Date2015-08-11 12:00 +0200
Subject[PATCH v3 3/4] clocksource: tcb_clksrc: fix setup_clkevents error path
Message-ID<pWevG-1vq-47@gated-at.bofh.it>
In reply to#1204975
From: Boris Brezillon <boris.brezillon@free-electrons.com>

t2_clk is already disabled before request_irq(), it must not be disabled
again.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
---
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
 drivers/clocksource/tcb_clksrc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clocksource/tcb_clksrc.c b/drivers/clocksource/tcb_clksrc.c
index 8bdbc45c6dad..b9b7277173c2 100644
--- a/drivers/clocksource/tcb_clksrc.c
+++ b/drivers/clocksource/tcb_clksrc.c
@@ -199,7 +199,7 @@ static int __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx)
 
 	ret = request_irq(irq, ch2_irq, IRQF_TIMER, "tc_clkevt", &clkevt);
 	if (ret) {
-		clk_disable_unprepare(t2_clk);
+		clk_unprepare(t2_clk);
 		return ret;
 	}
 
-- 
2.1.4

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#1205136 — Re: [PATCH v3 3/4] clocksource: tcb_clksrc: fix setup_clkevents error path

FromDaniel Lezcano <daniel.lezcano@linaro.org>
Date2015-08-11 15:30 +0200
SubjectRe: [PATCH v3 3/4] clocksource: tcb_clksrc: fix setup_clkevents error path
Message-ID<pWhMS-6mR-19@gated-at.bofh.it>
In reply to#1204983
On 08/11/2015 11:38 AM, Alexandre Belloni wrote:
> From: Boris Brezillon <boris.brezillon@free-electrons.com>
>
> t2_clk is already disabled before request_irq(), it must not be disabled
> again.
>
> Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
> ---

Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>


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#1204991 — [PATCH v3 2/4] clocksource: atmel-st: get and use slow clock

FromAlexandre Belloni <alexandre.belloni@free-electrons.com>
Date2015-08-11 12:00 +0200
Subject[PATCH v3 2/4] clocksource: atmel-st: get and use slow clock
Message-ID<pWevG-1vq-59@gated-at.bofh.it>
In reply to#1204975
The current slow clock rate is hardcoded. Properly get the slow clock
and use its rate.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
---
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
 drivers/clocksource/timer-atmel-st.c | 31 ++++++++++++++++++++++---------
 1 file changed, 22 insertions(+), 9 deletions(-)

diff --git a/drivers/clocksource/timer-atmel-st.c b/drivers/clocksource/timer-atmel-st.c
index 1692e17e096b..51dcbae0a654 100644
--- a/drivers/clocksource/timer-atmel-st.c
+++ b/drivers/clocksource/timer-atmel-st.c
@@ -22,6 +22,7 @@
 #include <linux/kernel.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
+#include <linux/clk.h>
 #include <linux/clockchips.h>
 #include <linux/export.h>
 #include <linux/mfd/syscon.h>
@@ -33,9 +34,7 @@ static unsigned long last_crtr;
 static u32 irqmask;
 static struct clock_event_device clkevt;
 static struct regmap *regmap_st;
-
-#define AT91_SLOW_CLOCK		32768
-#define RM9200_TIMER_LATCH	((AT91_SLOW_CLOCK + HZ/2) / HZ)
+static int timer_latch;
 
 /*
  * The ST_CRTR is updated asynchronously to the master clock ... but
@@ -82,8 +81,8 @@ static irqreturn_t at91rm9200_timer_interrupt(int irq, void *dev_id)
 	if (sr & AT91_ST_PITS) {
 		u32	crtr = read_CRTR();
 
-		while (((crtr - last_crtr) & AT91_ST_CRTV) >= RM9200_TIMER_LATCH) {
-			last_crtr += RM9200_TIMER_LATCH;
+		while (((crtr - last_crtr) & AT91_ST_CRTV) >= timer_latch) {
+			last_crtr += timer_latch;
 			clkevt.event_handler(&clkevt);
 		}
 		return IRQ_HANDLED;
@@ -120,7 +119,7 @@ clkevt32k_mode(enum clock_event_mode mode, struct clock_event_device *dev)
 	case CLOCK_EVT_MODE_PERIODIC:
 		/* PIT for periodic irqs; fixed rate of 1/HZ */
 		irqmask = AT91_ST_PITS;
-		regmap_write(regmap_st, AT91_ST_PIMR, RM9200_TIMER_LATCH);
+		regmap_write(regmap_st, AT91_ST_PIMR, timer_latch);
 		break;
 	case CLOCK_EVT_MODE_ONESHOT:
 		/* ALM for oneshot irqs, set by next_event()
@@ -182,7 +181,8 @@ static struct clock_event_device clkevt = {
  */
 static void __init atmel_st_timer_init(struct device_node *node)
 {
-	unsigned int val;
+	struct clk *sclk;
+	unsigned int sclk_rate, val;
 	int irq, ret;
 
 	regmap_st = syscon_node_to_regmap(node);
@@ -206,6 +206,19 @@ static void __init atmel_st_timer_init(struct device_node *node)
 	if (ret)
 		panic(pr_fmt("Unable to setup IRQ\n"));
 
+	sclk = of_clk_get(node, 0);
+	if (IS_ERR(sclk))
+		panic(pr_fmt("Unable to get slow clock\n"));
+
+	clk_prepare_enable(sclk);
+	if (ret)
+		panic(pr_fmt("Could not enable slow clock\n"));
+
+	sclk_rate = clk_get_rate(sclk);
+	if (!sclk_rate)
+		panic(pr_fmt("Invalid slow clock rate\n"));
+	timer_latch = (sclk_rate + HZ / 2) / HZ;
+
 	/* The 32KiHz "Slow Clock" (tick every 30517.58 nanoseconds) is used
 	 * directly for the clocksource and all clockevents, after adjusting
 	 * its prescaler from the 1 Hz default.
@@ -214,11 +227,11 @@ static void __init atmel_st_timer_init(struct device_node *node)
 
 	/* Setup timer clockevent, with minimum of two ticks (important!!) */
 	clkevt.cpumask = cpumask_of(0);
-	clockevents_config_and_register(&clkevt, AT91_SLOW_CLOCK,
+	clockevents_config_and_register(&clkevt, sclk_rate,
 					2, AT91_ST_ALMV);
 
 	/* register clocksource */
-	clocksource_register_hz(&clk32k, AT91_SLOW_CLOCK);
+	clocksource_register_hz(&clk32k, sclk_rate);
 }
 CLOCKSOURCE_OF_DECLARE(atmel_st_timer, "atmel,at91rm9200-st",
 		       atmel_st_timer_init);
-- 
2.1.4

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#1205133 — Re: [PATCH v3 2/4] clocksource: atmel-st: get and use slow clock

FromDaniel Lezcano <daniel.lezcano@linaro.org>
Date2015-08-11 15:30 +0200
SubjectRe: [PATCH v3 2/4] clocksource: atmel-st: get and use slow clock
Message-ID<pWhMR-6mR-5@gated-at.bofh.it>
In reply to#1204991
On 08/11/2015 11:38 AM, Alexandre Belloni wrote:
> The current slow clock rate is hardcoded. Properly get the slow clock
> and use its rate.
>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>

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