Re: [PATCH v2 4/9] clocksource: mediatek: Use GPT as sched clock source

[Matthias Brugger]

2015-05-16 9:58 GMT+02:00 Yingjoe Chen <yingjoe.chen@xxxxxxxxxxxx>:
> When cpu is in deep idle, arch timer will stop counting. Setup GPT as
> sched clock source so it can keep counting in idle.
>
> Signed-off-by: Yingjoe Chen <yingjoe.chen@xxxxxxxxxxxx>
> ---
>  drivers/clocksource/mtk_timer.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/drivers/clocksource/mtk_timer.c b/drivers/clocksource/mtk_timer.c
> index 91206f9..fe7cf72 100644
> --- a/drivers/clocksource/mtk_timer.c
> +++ b/drivers/clocksource/mtk_timer.c
> @@ -24,6 +24,7 @@
>  #include <linux/of.h>
>  #include <linux/of_address.h>
>  #include <linux/of_irq.h>
> +#include <linux/sched_clock.h>
>  #include <linux/slab.h>
>
>  #define GPT_IRQ_EN_REG         0x00
> @@ -59,6 +60,13 @@ struct mtk_clock_event_device {
>         struct clock_event_device dev;
>  };
>
> +static void __iomem *gpt_base __read_mostly;
> +
> +static u64 notrace mtk_read_sched_clock(void)
> +{
> +       return readl_relaxed(gpt_base + TIMER_CNT_REG(GPT_CLK_SRC));
> +}
> +
>  static inline struct mtk_clock_event_device *to_mtk_clk(
>                                 struct clock_event_device *c)
>  {
> @@ -243,6 +251,8 @@ static void __init mtk_timer_init(struct device_node *node)
>         mtk_timer_setup(evt, GPT_CLK_SRC, TIMER_CTRL_OP_FREERUN, 1);
>         clocksource_mmio_init(evt->gpt_base + TIMER_CNT_REG(GPT_CLK_SRC),
>                         node->name, rate, 300, 32, clocksource_mmio_readl_up);
> +       gpt_base = evt->gpt_base;

This is really hacky. We should clean up the code and provide
mtk_clock_event_device globally.
Please add the patch below, which does exactly this.
---- 8< ---------------- >8 ------