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
Those reset values have been extracted from a Raspberry Pi 3 model B
v1.2, using the 2020-08-20 version of raspios. The dump was done using
the debugfs interface of the CPRMAN driver in Linux (under
'/sys/kernel/debug/clk'). Each exposed clock tree stage (PLLs, channels
and muxes) can be observed by reading the 'regdump' file (e.g.
'plla/regdump').
Those values are set by the Raspberry Pi firmware at boot time (Linux
expects them to be set when it boots up).
Some stages are not exposed by the Linux driver (e.g. the PLL B). For
those, the reset values are unknown and left to 0 which implies a
disabled output.
Once booted in QEMU, the final clock tree is very similar to the one
visible on real hardware. The differences come from some unimplemented
devices for which the driver simply disable the corresponding clock.
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Luc Michel <luc@lmichel.fr>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This simple mux sits between the PLL channels and the DSI0E and DSI0P
clock muxes. This mux selects between PLLA-DSI0 and PLLD-DSI0 channel
and outputs the selected signal to source number 4 of DSI0E/P clock
muxes. It is controlled by the cm_dsi0hsck register.
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Luc Michel <luc@lmichel.fr>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
A clock mux can be configured to select one of its 10 sources through
the CM_CTL register. It also embeds yet another clock divider, composed
of an integer part and a fractional part. The number of bits of each
part is mux dependent.
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Luc Michel <luc@lmichel.fr>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
The clock multiplexers are the last clock stage in the CPRMAN. Each mux
outputs one clock signal that goes out of the CPRMAN to the SoC
peripherals.
Each mux has at most 10 sources. The sources 0 to 3 are common to all
muxes. They are:
0. ground (no clock signal)
1. the main oscillator (xosc)
2. "test debug 0" clock
3. "test debug 1" clock
Test debug 0 and 1 are actual clock muxes that can be used as sources to
other muxes (for debug purpose).
Sources 4 to 9 are mux specific and can be unpopulated (grounded). Those
sources are fed by the PLL channels outputs.
One corner case exists for DSI0E and DSI0P muxes. They have their source
number 4 connected to an intermediate multiplexer that can select
between PLLA-DSI0 and PLLD-DSI0 channel. This multiplexer is called
DSI0HSCK and is not a clock mux as such. It is really a simple mux from
the hardware point of view (see https://elinux.org/The_Undocumented_Pi).
This mux is not implemented in this commit.
Note that there is some muxes for which sources are unknown (because of
a lack of documentation). For those cases all the sources are connected
to ground in this implementation.
Each clock mux output is exported by the CPRMAN at the qdev level,
adding the suffix '-out' to the mux name to form the output clock name.
(E.g. the 'uart' mux sees its output exported as 'uart-out' at the
CPRMAN level.)
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Luc Michel <luc@lmichel.fr>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
A PLL channel is able to further divide the generated PLL frequency.
The divider is given in the CTRL_A2W register. Some channels have an
additional fixed divider which is always applied to the signal.
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Luc Michel <luc@lmichel.fr>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
PLLs are composed of multiple channels. Each channel outputs one clock
signal. They are modeled as one device taking the PLL generated clock as
input, and outputting a new clock.
A channel shares the CM register with its parent PLL, and has its own
A2W_CTRL register. A write to the CM register will trigger an update of
the PLL and all its channels, while a write to an A2W_CTRL channel
register will update the required channel only.
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Luc Michel <luc@lmichel.fr>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
The CPRMAN PLLs generate a clock based on a prescaler, a multiplier and
a divider. The prescaler doubles the parent (xosc) frequency, then the
multiplier/divider are applied. The multiplier has an integer and a
fractional part.
This commit also implements the CPRMAN CM_LOCK register. This register
reports which PLL is currently locked. We consider a PLL has being
locked as soon as it is enabled (on real hardware, there is a delay
after turning a PLL on, for it to stabilize).
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Luc Michel <luc@lmichel.fr>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
There are 5 PLLs in the CPRMAN, namely PLL A, C, D, H and B. All of them
take the xosc clock as input and produce a new clock.
This commit adds a skeleton implementation for the PLLs as sub-devices
of the CPRMAN. The PLLs are instantiated and connected internally to the
main oscillator.
Each PLL has 6 registers : CM, A2W_CTRL, A2W_ANA[0,1,2,3], A2W_FRAC. A
write to any of them triggers a call to the (not yet implemented)
pll_update function.
If the main oscillator changes frequency, an update is also triggered.
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Luc Michel <luc@lmichel.fr>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
The BCM2835 CPRMAN is the clock manager of the SoC. It is composed of a
main oscillator, and several sub-components (PLLs, multiplexers, ...) to
generate the BCM2835 clock tree.
This commit adds a skeleton of the CPRMAN, with a dummy register
read/write implementation. It embeds the main oscillator (xosc) from
which all the clocks will be derived.
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Luc Michel <luc@lmichel.fr>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
