Commit-ID: 70c62cf910aeba7cb79f4ebc7e6c8edbb37a77f6 Gitweb: https://git.kernel.org/tip/70c62cf910aeba7cb79f4ebc7e6c8edbb37a77f6 Author: Daniel Lezcano <daniel.lezc...@linaro.org> AuthorDate: Mon, 8 Jan 2018 14:28:53 +0100 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Mon, 8 Jan 2018 17:57:25 +0100
clocksource/drivers/stm32: Factor out the timer width sorting code In order to clarify and encapsulate the code for upcoming changes, move the timer width check into a function and add some documentation. Tested-by: Benjamin Gaignard <benjamin.gaign...@st.com> Signed-off-by: Daniel Lezcano <daniel.lezc...@linaro.org> Acked-by: Benjamin Gaignard <benjamin.gaign...@st.com> Cc: Alexandre Torgue <alexandre.tor...@st.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Maxime Coquelin <mcoquelin.st...@gmail.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Link: http://lkml.kernel.org/r/1515418139-23276-14-git-send-email-daniel.lezc...@linaro.org [ Spelling fixes. ] Signed-off-by: Ingo Molnar <mi...@kernel.org> --- drivers/clocksource/timer-stm32.c | 30 +++++++++++++++++++++++------- 1 file changed, 23 insertions(+), 7 deletions(-) diff --git a/drivers/clocksource/timer-stm32.c b/drivers/clocksource/timer-stm32.c index 14b7a2b..33c7c90 100644 --- a/drivers/clocksource/timer-stm32.c +++ b/drivers/clocksource/timer-stm32.c @@ -80,9 +80,27 @@ static irqreturn_t stm32_clock_event_handler(int irq, void *dev_id) return IRQ_HANDLED; } +/** + * stm32_timer_width - Sort out the timer width (32/16) + * @to: a pointer to a timer-of structure + * + * Write the 32-bit max value and read/return the result. If the timer + * is 32 bits wide, the result will be UINT_MAX, otherwise it will + * be truncated by the 16-bit register to USHRT_MAX. + * + * Returns UINT_MAX if the timer is 32 bits wide, USHRT_MAX if it is a + * 16 bits wide. + */ +static u32 __init stm32_timer_width(struct timer_of *to) +{ + writel_relaxed(UINT_MAX, timer_of_base(to) + TIM_ARR); + + return readl_relaxed(timer_of_base(to) + TIM_ARR); +} + static void __init stm32_clockevent_init(struct timer_of *to) { - unsigned long max_delta; + u32 width = 0; int prescaler; to->clkevt.name = to->np->full_name; @@ -93,10 +111,8 @@ static void __init stm32_clockevent_init(struct timer_of *to) to->clkevt.tick_resume = stm32_clock_event_shutdown; to->clkevt.set_next_event = stm32_clock_event_set_next_event; - /* Detect whether the timer is 16 or 32 bits */ - writel_relaxed(~0U, timer_of_base(to) + TIM_ARR); - max_delta = readl_relaxed(timer_of_base(to) + TIM_ARR); - if (max_delta == ~0U) { + width = stm32_timer_width(to); + if (width == UINT_MAX) { prescaler = 1; to->clkevt.rating = 250; } else { @@ -115,10 +131,10 @@ static void __init stm32_clockevent_init(struct timer_of *to) to->of_clk.period = DIV_ROUND_UP(to->of_clk.rate, HZ); clockevents_config_and_register(&to->clkevt, - timer_of_rate(to), 0x1, max_delta); + timer_of_rate(to), 0x1, width); pr_info("%pOF: STM32 clockevent driver initialized (%d bits)\n", - to->np, max_delta == UINT_MAX ? 32 : 16); + to->np, width == UINT_MAX ? 32 : 16); } static int __init stm32_timer_init(struct device_node *node)
