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timer: Add helper for drivers using timebase fallback

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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>
Reviewed-by: Rick Chen <rick@andestech.com>
This commit is contained in:
Sean Anderson 2020-09-28 10:52:22 -04:00 committed by Andes
parent c33efafaf9
commit 3576121687
2 changed files with 46 additions and 0 deletions
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31
drivers/timer/timer-uclass.c
View File

@ -4,6 +4,7 @@
*/
#include <common.h>
#include <cpu.h>
#include <dm.h>
#include <init.h>
#include <dm/lists.h>
@ -79,6 +80,36 @@ static int timer_post_probe(struct udevice *dev)
return 0;
}
/*
* TODO: should be CONFIG_IS_ENABLED(CPU), but the SPL config has _SUPPORT on
* the end...
*/
#if defined(CONFIG_CPU) || defined(CONFIG_SPL_CPU_SUPPORT)
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;
}
#endif
u64 timer_conv_64(u32 count)
{
/* increment tbh if tbl has rolled over */

15
include/timer.h
View File

@ -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
*