It is quite common for a clock tree to involve possibly programmable
clock multipliers or dividers, where the frequency of a clock is for
instance divided by 8 to produce a slower clock to feed to a
particular device.
Currently we provide no convenient mechanism for modelling this. You
can implement it by having an input Clock and an output Clock, and
manually setting the period of the output clock in the period-changed
callback of the input clock, but that's quite clunky.
This patch adds support in the Clock objects themselves for setting a
multiplier or divider. The effect of setting this on a clock is that
when the clock's period is changed, all the children of the clock are
set to period * multiplier / divider, rather than being set to the
same period as the parent clock.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alexandre Iooss <erdnaxe@crans.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Luc Michel <luc@lmichel.fr>
Reviewed-by: Damien Hedde <damien.hedde@greensocs.com>
Message-id: 20210812093356.1946-10-peter.maydell@linaro.org
Add a new callback event type ClockPreUpdate, which is called on
period changes before the period is updated.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Luc Michel <luc@lmichel.fr>
Reviewed-by: Hao Wu <wuhaotsh@google.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20210219144617.4782-3-peter.maydell@linaro.org
The Clock framework allows users to specify a callback which is
called after the clock's period has been updated. Some users need to
also have a callback which is called before the clock period is
updated.
As the first step in adding support for notifying Clock users on
pre-update events, add an argument to the ClockCallback to specify
what event is being notified, and add an argument to the various
functions for registering a callback to specify which events are
of interest to that callback.
Note that the documentation update renders correct the previously
incorrect claim in 'Adding a new clock' that callbacks "will be
explained in a following section".
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Luc Michel <luc@lmichel.fr>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210219144617.4782-2-peter.maydell@linaro.org
It's common to want to print a human-readable indication of a clock's
frequency. Provide a utility function in the clock API to return a
string which is a displayable representation of the frequency,
and use it in qdev-monitor.c.
Before:
(qemu) info qtree
[...]
dev: xilinx,zynq_slcr, id ""
clock-in "ps_clk" freq_hz=3.333333e+07
mmio 00000000f8000000/0000000000001000
After:
dev: xilinx,zynq_slcr, id ""
clock-in "ps_clk" freq_hz=33.3 MHz
mmio 00000000f8000000/0000000000001000
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Luc Michel <luc@lmichel.fr>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20201215150929.30311-5-peter.maydell@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
The nanosecond unit greatly limits the dynamic range we can display in
clock value traces, for values in the order of 1GHz and more. The
internal representation can go way beyond this value and it is quite
common for today's clocks to be within those ranges.
For example, a frequency between 500MHz+ and 1GHz will be displayed as
1ns. Beyond 1GHz, it will show up as 0ns.
Replace nanosecond periods traces with frequencies in the Hz unit
to have more dynamic range in the trace output.
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Damien Hedde <damien.hedde@greensocs.com>
Signed-off-by: Luc Michel <luc@lmichel.fr>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This function creates a clock and parents it to another object with a
given name. It calls clock_setup_canonical_path before returning the
new clock.
This function is useful to create clocks in devices when one doesn't
want to expose it at the qdev level (as an input or an output).
Suggested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Luc Michel <luc@lmichel.fr>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20201010135759.437903-4-luc@lmichel.fr>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Let clock_set() return a boolean value whether the clock
has been updated or not.
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200806123858.30058-3-f4bug@amsat.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This object may be used to represent a clock inside a clock tree.
A clock may be connected to another clock so that it receives update,
through a callback, whenever the source/parent clock is updated.
Although only the root clock of a clock tree controls the values
(represented as periods) of all clocks in tree, each clock holds
a local state containing the current value so that it can be fetched
independently. It will allows us to fullfill migration requirements
by migrating each clock independently of others.
This is based on the original work of Frederic Konrad.
Signed-off-by: Damien Hedde <damien.hedde@greensocs.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Message-id: 20200406135251.157596-2-damien.hedde@greensocs.com
[PMM: Use uint64_t rather than unsigned long long in trace events;
the dtrace backend can't handle the latter]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
