Re: [PATCH 3/7] clocksource/cadence_ttc: Store timer frequency in driver data

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On 11/08/2013 10:21 PM, Soren Brinkmann wrote:
It is not allowed to call clk_get_rate() from interrupt context. To
avoid such calls the timer input frequency is stored in the driver's
data struct which makes it accessible to the driver in any context.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xxxxxxxxxx>
---

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

  drivers/clocksource/cadence_ttc_timer.c | 21 +++++++++++++--------
  1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/drivers/clocksource/cadence_ttc_timer.c b/drivers/clocksource/cadence_ttc_timer.c
index b2bb3a4bc205..a92350b55d32 100644
--- a/drivers/clocksource/cadence_ttc_timer.c
+++ b/drivers/clocksource/cadence_ttc_timer.c
@@ -67,11 +67,13 @@
   * struct ttc_timer - This definition defines local timer structure
   *
   * @base_addr:	Base address of timer
+ * @freq:	Timer input clock frequency
   * @clk:	Associated clock source
   * @clk_rate_change_nb	Notifier block for clock rate changes
   */
  struct ttc_timer {
  	void __iomem *base_addr;
+	unsigned long freq;
  	struct clk *clk;
  	struct notifier_block clk_rate_change_nb;
  };
@@ -196,9 +198,8 @@ static void ttc_set_mode(enum clock_event_mode mode,

  	switch (mode) {
  	case CLOCK_EVT_MODE_PERIODIC:
-		ttc_set_interval(timer,
-				DIV_ROUND_CLOSEST(clk_get_rate(ttce->ttc.clk),
-					PRESCALE * HZ));
+		ttc_set_interval(timer, DIV_ROUND_CLOSEST(ttce->ttc.freq,
+						PRESCALE * HZ));
  		break;
  	case CLOCK_EVT_MODE_ONESHOT:
  	case CLOCK_EVT_MODE_UNUSED:
@@ -273,6 +274,8 @@ static void __init ttc_setup_clocksource(struct clk *clk, void __iomem *base)
  		return;
  	}

+	ttccs->ttc.freq = clk_get_rate(ttccs->ttc.clk);
+
  	ttccs->ttc.clk_rate_change_nb.notifier_call =
  		ttc_rate_change_clocksource_cb;
  	ttccs->ttc.clk_rate_change_nb.next = NULL;
@@ -298,16 +301,14 @@ static void __init ttc_setup_clocksource(struct clk *clk, void __iomem *base)
  	__raw_writel(CNT_CNTRL_RESET,
  		     ttccs->ttc.base_addr + TTC_CNT_CNTRL_OFFSET);

-	err = clocksource_register_hz(&ttccs->cs,
-			clk_get_rate(ttccs->ttc.clk) / PRESCALE);
+	err = clocksource_register_hz(&ttccs->cs, ttccs->ttc.freq / PRESCALE);
  	if (WARN_ON(err)) {
  		kfree(ttccs);
  		return;
  	}

  	ttc_sched_clock_val_reg = base + TTC_COUNT_VAL_OFFSET;
-	setup_sched_clock(ttc_sched_clock_read, 16,
-			clk_get_rate(ttccs->ttc.clk) / PRESCALE);
+	setup_sched_clock(ttc_sched_clock_read, 16, ttccs->ttc.freq / PRESCALE);
  }

  static int ttc_rate_change_clockevent_cb(struct notifier_block *nb,
@@ -334,6 +335,9 @@ static int ttc_rate_change_clockevent_cb(struct notifier_block *nb,
  				ndata->new_rate / PRESCALE);
  		local_irq_restore(flags);

+		/* update cached frequency */
+		ttc->freq = ndata->new_rate;
+
  		/* fall through */
  	}
  	case PRE_RATE_CHANGE:
@@ -367,6 +371,7 @@ static void __init ttc_setup_clockevent(struct clk *clk,
  	if (clk_notifier_register(ttcce->ttc.clk,
  				&ttcce->ttc.clk_rate_change_nb))
  		pr_warn("Unable to register clock notifier.\n");
+	ttcce->ttc.freq = clk_get_rate(ttcce->ttc.clk);

  	ttcce->ttc.base_addr = base;
  	ttcce->ce.name = "ttc_clockevent";
@@ -396,7 +401,7 @@ static void __init ttc_setup_clockevent(struct clk *clk,
  	}

  	clockevents_config_and_register(&ttcce->ce,
-			clk_get_rate(ttcce->ttc.clk) / PRESCALE, 1, 0xfffe);
+			ttcce->ttc.freq / PRESCALE, 1, 0xfffe);
  }

  /**



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