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 seanga2@gmail.com Reviewed-by: Simon Glass sjg@chromium.org Reviewed-by: Bin Meng bin.meng@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(); + 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 *