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Message-Id: <1515418139-23276-17-git-send-email-daniel.lezcano@linaro.org>
Date: Mon, 8 Jan 2018 14:28:56 +0100
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: tglx@...utronix.de
Cc: linux-kernel@...r.kernel.org,
Benjamin Gaignard <benjamin.gaignard@...com>,
Maxime Coquelin <mcoquelin.stm32@...il.com>,
Alexandre Torgue <alexandre.torgue@...com>,
linux-arm-kernel@...ts.infradead.org (moderated list:ARM/STM32
ARCHITECTURE)
Subject: [PATCH 17/20] clocksource/drivers/stm32: Encapsulate more the clockevent code
In order to prepare the clocksource code, let's encapsulate the clockevent
code, split the prescaler and timer width code into separate functions.
Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
Tested-by: Benjamin Gaignard <benjamin.gaignard@...com>
Acked-by: Benjamin Gaignard <benjamin.gaignard@...com>
---
drivers/clocksource/timer-stm32.c | 107 +++++++++++++++++++++++++++++---------
1 file changed, 82 insertions(+), 25 deletions(-)
diff --git a/drivers/clocksource/timer-stm32.c b/drivers/clocksource/timer-stm32.c
index baca42c..1891924 100644
--- a/drivers/clocksource/timer-stm32.c
+++ b/drivers/clocksource/timer-stm32.c
@@ -44,6 +44,42 @@
#define TIM_PSC_MAX USHRT_MAX
#define TIM_PSC_CLKRATE 10000
+struct stm32_timer_private {
+ int bits;
+};
+
+/**
+ * stm32_timer_of_bits_set - set accessor helper
+ * @to: a timer_of structure pointer
+ * @bits: the number of bits (16 or 32)
+ *
+ * Accessor helper to set the number of bits in the timer-of private
+ * structure.
+ *
+ */
+static void stm32_timer_of_bits_set(struct timer_of *to, int bits)
+{
+ struct stm32_timer_private *pd = to->private_data;
+
+ pd->bits = bits;
+}
+
+/**
+ * stm32_timer_of_bits_get - get accessor helper
+ * @to: a timer_of structure pointer
+ *
+ * Accessor helper to get the number of bits in the timer-of private
+ * structure.
+ *
+ * Returns an integer corresponding to the number of bits.
+ */
+static int stm32_timer_of_bits_get(struct timer_of *to)
+{
+ struct stm32_timer_private *pd = to->private_data;
+
+ return pd->bits;
+}
+
static void stm32_clock_event_disable(struct timer_of *to)
{
writel_relaxed(0, timer_of_base(to) + TIM_DIER);
@@ -124,35 +160,31 @@ static irqreturn_t stm32_clock_event_handler(int irq, void *dev_id)
* is a 32bits width, the result will be UINT_MAX, otherwise it will
* be truncated by the 16bits register to USHRT_MAX.
*
- * Returns UINT_MAX if the timer is 32bits width, USHRT_MAX if it is a
- * 16bits width.
*/
-static u32 __init stm32_timer_width(struct timer_of *to)
+static void __init stm32_timer_set_width(struct timer_of *to)
{
+ u32 width;
+
writel_relaxed(UINT_MAX, timer_of_base(to) + TIM_ARR);
- return readl_relaxed(timer_of_base(to) + TIM_ARR);
+ width = readl_relaxed(timer_of_base(to) + TIM_ARR);
+
+ stm32_timer_of_bits_set(to, width == UINT_MAX ? 32 : 16);
}
-static void __init stm32_clockevent_init(struct timer_of *to)
+/**
+ * stm32_timer_set_prescaler - Compute and set the prescaler register
+ * @to: a pointer to a timer-of structure
+ *
+ * Depending on the timer width, compute the prescaler to always
+ * target a 10MHz timer rate for the 16bits. 32bits timers are
+ * considered precise and long enough to not use the prescaler.
+ */
+static void __init stm32_timer_set_prescaler(struct timer_of *to)
{
- u32 width = 0;
- int prescaler;
+ int prescaler = 1;
- to->clkevt.name = to->np->full_name;
- to->clkevt.features = CLOCK_EVT_FEAT_PERIODIC;
- to->clkevt.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
- to->clkevt.set_state_shutdown = stm32_clock_event_shutdown;
- to->clkevt.set_state_periodic = stm32_clock_event_set_periodic;
- to->clkevt.set_state_oneshot = stm32_clock_event_set_oneshot;
- to->clkevt.tick_resume = stm32_clock_event_shutdown;
- to->clkevt.set_next_event = stm32_clock_event_set_next_event;
-
- width = stm32_timer_width(to);
- if (width == UINT_MAX) {
- prescaler = 1;
- to->clkevt.rating = 250;
- } else {
+ if (stm32_timer_of_bits_get(to) != 32) {
prescaler = DIV_ROUND_CLOSEST(timer_of_rate(to),
TIM_PSC_CLKRATE);
/*
@@ -161,7 +193,6 @@ static void __init stm32_clockevent_init(struct timer_of *to)
* this case.
*/
prescaler = prescaler < TIM_PSC_MAX ? prescaler : TIM_PSC_MAX;
- to->clkevt.rating = 100;
}
writel_relaxed(prescaler - 1, timer_of_base(to) + TIM_PSC);
@@ -171,12 +202,26 @@ static void __init stm32_clockevent_init(struct timer_of *to)
/* Adjust rate and period given the prescaler value */
to->of_clk.rate = DIV_ROUND_CLOSEST(to->of_clk.rate, prescaler);
to->of_clk.period = DIV_ROUND_UP(to->of_clk.rate, HZ);
+}
+
+static void __init stm32_clockevent_init(struct timer_of *to)
+{
+ u32 bits = stm32_timer_of_bits_get(to);
- clockevents_config_and_register(&to->clkevt,
- timer_of_rate(to), 0x1, width);
+ to->clkevt.name = to->np->full_name;
+ to->clkevt.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
+ to->clkevt.set_state_shutdown = stm32_clock_event_shutdown;
+ to->clkevt.set_state_periodic = stm32_clock_event_set_periodic;
+ to->clkevt.set_state_oneshot = stm32_clock_event_set_oneshot;
+ to->clkevt.tick_resume = stm32_clock_event_shutdown;
+ to->clkevt.set_next_event = stm32_clock_event_set_next_event;
+ to->clkevt.rating = bits == 32 ? 250 : 100;
+
+ clockevents_config_and_register(&to->clkevt, timer_of_rate(to), 0x1,
+ (1 << bits) - 1);
pr_info("%pOF: STM32 clockevent driver initialized (%d bits)\n",
- to->np, width == UINT_MAX ? 32 : 16);
+ to->np, bits);
}
static int __init stm32_timer_init(struct device_node *node)
@@ -196,14 +241,26 @@ static int __init stm32_timer_init(struct device_node *node)
if (ret)
goto err;
+ to->private_data = kzalloc(sizeof(struct stm32_timer_private),
+ GFP_KERNEL);
+ if (!to->private_data)
+ goto deinit;
+
rstc = of_reset_control_get(node, NULL);
if (!IS_ERR(rstc)) {
reset_control_assert(rstc);
reset_control_deassert(rstc);
}
+ stm32_timer_set_width(to);
+
+ stm32_timer_set_prescaler(to);
+
stm32_clockevent_init(to);
return 0;
+
+deinit:
+ timer_of_cleanup(to);
err:
kfree(to);
return ret;
--
2.7.4
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