Re: [PATCH v5 1/3] clocksource/drivers/atcpit100: Add andestech atcpit100 timer

From: Daniel Lezcano
Date: Tue Dec 12 2017 - 05:06:10 EST


On 12/12/2017 06:46, Rick Chen wrote:
> ATCPIT100 is often used on the Andes architecture,
> This timer provide 4 PIT channels. Each PIT channel is a
> multi-function timer, can be configured as 32,16,8 bit timers
> or PWM as well.
>
> For system timer it will set channel 1 32-bit timer0 as clock
> source and count downwards until underflow and restart again.

[ ... ]

> +config CLKSRC_ATCPIT100
> + bool "Clocksource for AE3XX platform"
> + depends on NDS32 || COMPILE_TEST
> + depends on HAS_IOMEM
> + help
> + This option enables support for the Andestech AE3XX platform timers.

Hi Rick,

the general rule for the Kconfig is:

bool "Clocksource for AE3XX platform" if COMPILE_TEST

and no deps on the platform.

It is up to the platform Kconfig to select the option.

We want here a silent option but make it selectable in case of
compilation test coverage.

Also, this driver is not a CLKSRC but a TIMER. Rename CLKSRC_ATCPIT100
to TIMER_ATCPIT100.

> +
> endmenu
> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> index 72711f1..7d072f5 100644
> --- a/drivers/clocksource/Makefile
> +++ b/drivers/clocksource/Makefile
> @@ -75,3 +75,4 @@ obj-$(CONFIG_H8300_TMR16) += h8300_timer16.o
> obj-$(CONFIG_H8300_TPU) += h8300_tpu.o
> obj-$(CONFIG_CLKSRC_ST_LPC) += clksrc_st_lpc.o
> obj-$(CONFIG_X86_NUMACHIP) += numachip.o
> +obj-$(CONFIG_CLKSRC_ATCPIT100) += timer-atcpit100.o

[ ... ]

> +static struct timer_of to = {
> + .flags = TIMER_OF_IRQ | TIMER_OF_CLOCK | TIMER_OF_BASE,
> +
> + .clkevt = {
> + .name = "atcpit100_tick",
> + .rating = 300,
> + .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
> + .set_state_shutdown = atcpit100_clkevt_shutdown,
> + .set_state_periodic = atcpit100_clkevt_set_periodic,
> + .set_state_oneshot = atcpit100_clkevt_set_oneshot,
> + .tick_resume = atcpit100_clkevt_shutdown,
> + .set_next_event = atcpit100_clkevt_next_event,
> + .cpumask = cpu_all_mask,

You may consider CLOCK_EVT_DYN_IRQ
https://lwn.net/Articles/540160/

> + },
> +
> + .of_irq = {
> + .handler = atcpit100_timer_interrupt,
> + .flags = IRQF_TIMER | IRQF_IRQPOLL,
> + },
> +
> + /*
> + * FIXME: we currently only support clocking using PCLK
> + * and using EXTCLK is not supported in the driver.
> + */
> + .of_clk = {
> + .name = "PCLK",
> + }

What do you mean ? We can't specify several clock names with timer-of?


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