diff options
| -rw-r--r-- | docs/devel/clocks.rst | 4 | ||||
| -rw-r--r-- | hw/core/clock.c | 8 | ||||
| -rw-r--r-- | include/hw/clock.h | 4 |
3 files changed, 14 insertions, 2 deletions
diff --git a/docs/devel/clocks.rst b/docs/devel/clocks.rst index c4d14bd..b2d1148 100644 --- a/docs/devel/clocks.rst +++ b/docs/devel/clocks.rst @@ -279,6 +279,10 @@ You can change the multiplier and divider of a clock at runtime, so you can use this to model clock controller devices which have guest-programmable frequency multipliers or dividers. +Similary to ``clock_set()``, ``clock_set_mul_div()`` returns ``true`` if +the clock state was modified; that is, if the multiplier or the diviser +or both were changed by the call. + Note that ``clock_set_mul_div()`` does not automatically call ``clock_propagate()``. If you make a runtime change to the multiplier or divider you must call clock_propagate() yourself. diff --git a/hw/core/clock.c b/hw/core/clock.c index d82e44c..a19c7db 100644 --- a/hw/core/clock.c +++ b/hw/core/clock.c @@ -143,14 +143,20 @@ char *clock_display_freq(Clock *clk) return freq_to_str(clock_get_hz(clk)); } -void clock_set_mul_div(Clock *clk, uint32_t multiplier, uint32_t divider) +bool clock_set_mul_div(Clock *clk, uint32_t multiplier, uint32_t divider) { assert(divider != 0); + if (clk->multiplier == multiplier && clk->divider == divider) { + return false; + } + trace_clock_set_mul_div(CLOCK_PATH(clk), clk->multiplier, multiplier, clk->divider, divider); clk->multiplier = multiplier; clk->divider = divider; + + return true; } static void clock_initfn(Object *obj) diff --git a/include/hw/clock.h b/include/hw/clock.h index bb12117..eb58599 100644 --- a/include/hw/clock.h +++ b/include/hw/clock.h @@ -357,6 +357,8 @@ char *clock_display_freq(Clock *clk); * @multiplier: multiplier value * @divider: divider value * + * @return: true if the clock is changed. + * * By default, a Clock's children will all run with the same period * as their parent. This function allows you to adjust the multiplier * and divider used to derive the child clock frequency. @@ -374,6 +376,6 @@ char *clock_display_freq(Clock *clk); * Note that this function does not call clock_propagate(); the * caller should do that if necessary. */ -void clock_set_mul_div(Clock *clk, uint32_t multiplier, uint32_t divider); +bool clock_set_mul_div(Clock *clk, uint32_t multiplier, uint32_t divider); #endif /* QEMU_HW_CLOCK_H */ |