| Message ID | 20210409062401.2350436-6-f4bug@amsat.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | hw/clock: Strengthen machine (non-qdev) clock propagation | expand |
On Fri, 9 Apr 2021 at 07:24, Philippe Mathieu-Daudé <f4bug@amsat.org> wrote: > > Clocks are rarely left unconnected, but rather connected to ground > plane to avoid noise. When representing the clock tree, we want to > see such ground clock. As we might reuse this clock on various > boards, introduce the qdev_ground_clock() which return a singleton > ground clock. > > Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org> > --- > include/hw/qdev-clock.h | 9 +++++++++ > hw/core/qdev-clock.c | 11 +++++++++++ > 2 files changed, 20 insertions(+) > > diff --git a/include/hw/qdev-clock.h b/include/hw/qdev-clock.h > index ffa0f7ba09e..2f2d2da6cd6 100644 > --- a/include/hw/qdev-clock.h > +++ b/include/hw/qdev-clock.h > @@ -161,4 +161,13 @@ typedef struct ClockPortInitElem ClockPortInitArray[]; > */ > void qdev_init_clocks(DeviceState *dev, const ClockPortInitArray clocks); > > +/** > + * qdev_ground_clock: > + * @returns: a pointer to the ground clock > + * > + * Get the special 'ground' clock. This clock can be used as input > + * (unclocked) or output. > + */ > +Clock *qdev_ground_clock(void); > + > #endif /* QDEV_CLOCK_H */ > diff --git a/hw/core/qdev-clock.c b/hw/core/qdev-clock.c > index 117f4c6ea4a..a46384a84b7 100644 > --- a/hw/core/qdev-clock.c > +++ b/hw/core/qdev-clock.c > @@ -210,3 +210,14 @@ void qdev_connect_clock_in(DeviceState *dev, const char *name, Clock *source) > assert(!dev->realized); > clock_set_source(qdev_get_clock_in(dev, name), source); > } > + > +Clock *qdev_ground_clock(void) > +{ > + static Clock *gnd_clk; > + > + if (!gnd_clk) { > + gnd_clk = clock_new(qdev_get_machine(), "gnd"); > + } > + > + return gnd_clk; > +} I'm not really convinced that we need this, given that we have exactly one user of it in the tree. I think if you happen to want a fixed-frequency-0Hz clock it's not a big deal to just create it like any other clock. If we had half a dozen users in the tree I might feel differently. thanks -- PMM
diff --git a/include/hw/qdev-clock.h b/include/hw/qdev-clock.h index ffa0f7ba09e..2f2d2da6cd6 100644 --- a/include/hw/qdev-clock.h +++ b/include/hw/qdev-clock.h @@ -161,4 +161,13 @@ typedef struct ClockPortInitElem ClockPortInitArray[]; */ void qdev_init_clocks(DeviceState *dev, const ClockPortInitArray clocks); +/** + * qdev_ground_clock: + * @returns: a pointer to the ground clock + * + * Get the special 'ground' clock. This clock can be used as input + * (unclocked) or output. + */ +Clock *qdev_ground_clock(void); + #endif /* QDEV_CLOCK_H */ diff --git a/hw/core/qdev-clock.c b/hw/core/qdev-clock.c index 117f4c6ea4a..a46384a84b7 100644 --- a/hw/core/qdev-clock.c +++ b/hw/core/qdev-clock.c @@ -210,3 +210,14 @@ void qdev_connect_clock_in(DeviceState *dev, const char *name, Clock *source) assert(!dev->realized); clock_set_source(qdev_get_clock_in(dev, name), source); } + +Clock *qdev_ground_clock(void) +{ + static Clock *gnd_clk; + + if (!gnd_clk) { + gnd_clk = clock_new(qdev_get_machine(), "gnd"); + } + + return gnd_clk; +}
Clocks are rarely left unconnected, but rather connected to ground plane to avoid noise. When representing the clock tree, we want to see such ground clock. As we might reuse this clock on various boards, introduce the qdev_ground_clock() which return a singleton ground clock. Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org> --- include/hw/qdev-clock.h | 9 +++++++++ hw/core/qdev-clock.c | 11 +++++++++++ 2 files changed, 20 insertions(+)