Hi Sean
> This function is designed to be used when a timer used to be initialized by
> the cpu (e.g. RISC-V timers), but now is initialized by dm_timer_init. In
> such a case, the timer may prefer to use the clocks and clock-frequency
> properties, but should be able to fall back on using the cpu's
> timebase-frequency.
>
> Signed-off-by: Sean Anderson <sean...@gmail.com>
> Reviewed-by: Simon Glass <s...@chromium.org>
> Reviewed-by: Bin Meng <bin.m...@windriver.com>
> ---
>
> (no changes since v4)
>
> Changes in v4:
> - New
>
> drivers/timer/timer-uclass.c | 25 +++++++++++++++++++++++++
> include/timer.h | 15 +++++++++++++++
> 2 files changed, 40 insertions(+)
>
> diff --git a/drivers/timer/timer-uclass.c b/drivers/timer/timer-uclass.c
> index 14dde950a1..fb2f4c351a 100644
> --- a/drivers/timer/timer-uclass.c
> +++ b/drivers/timer/timer-uclass.c
> @@ -4,6 +4,7 @@
> */
>
> #include <common.h>
> +#include <cpu.h>
> #include <dm.h>
> #include <init.h>
> #include <dm/lists.h>
> @@ -79,6 +80,30 @@ static int timer_post_probe(struct udevice *dev)
> return 0;
> }
>
> +int timer_timebase_fallback(struct udevice *dev)
> +{
> + struct udevice *cpu;
> + struct cpu_platdata *cpu_plat;
> + struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
> +
> + /* Did we get our clock rate from the device tree? */
> + if (uc_priv->clock_rate)
> + return 0;
> +
> + /* Fall back to timebase-frequency */
> + dev_dbg(dev, "missing clocks or clock-frequency property; falling
> back on timebase-frequency\n");
> + cpu = cpu_get_current_dev();
It shall depend on CONFIG_CPU, please check about the fail item of CI:
https://travis-ci.org/github/rickchen36/u-boot-riscv/jobs/730170730
Thanks,
Rick
> + if (!cpu)
> + return -ENODEV;
> +
> + cpu_plat = dev_get_parent_platdata(cpu);
> + if (!cpu_plat)
> + return -ENODEV;
> +
> + uc_priv->clock_rate = cpu_plat->timebase_freq;
> + return 0;
> +}
> +
> u64 timer_conv_64(u32 count)
> {
> /* increment tbh if tbl has rolled over */
> diff --git a/include/timer.h b/include/timer.h
> index a49b500ce3..8b9fa51c53 100644
> --- a/include/timer.h
> +++ b/include/timer.h
> @@ -15,6 +15,21 @@
> */
> int dm_timer_init(void);
>
> +/**
> + * timer_timebase_fallback() - Helper for timers using timebase fallback
> + * @dev: A timer partially-probed timer device
> + *
> + * This is a helper function designed for timers which need to fall back on
> the
> + * cpu's timebase. This function is designed to be called during the driver's
> + * probe(). If there is a clocks or clock-frequency property in the timer's
> + * binding, then it will be used. Otherwise, the timebase of the current cpu
> + * will be used. This is initialized by the cpu driver, and usually gotten
> from
> + * ``/cpus/timebase-frequency`` or ``/cpus/cpu@X/timebase-frequency``.
> + *
> + * Return: 0 if OK, or negative error code on failure
> + */
> +int timer_timebase_fallback(struct udevice *dev);
> +
> /*
> * timer_conv_64 - convert 32-bit counter value to 64-bit
> *
> --
> 2.28.0
>
