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[PATCH 00/25] Convert CMSDK timer, watchdog, dualtimer to Clock framewor

From: Peter Maydell
Subject: [PATCH 00/25] Convert CMSDK timer, watchdog, dualtimer to Clock framework
Date: Thu, 21 Jan 2021 19:05:57 +0000

This patchset converts the CMSDK timer, watchdog and dualtimer devices
to use the Clock framework instead of an integer property specifying
a frequency in Hz. The series is quito a lot of patches but they
should be mostly small and I hope easy to review.

The motivation here is the upcoming Arm SSE-300 model: this has a
new kind of timer device, which I wanted to write in the modern style
with a Clock input. That meant the ARMSSE container object needed
to know about Clocks, so converting the existing devices it used
to Clocks seemed like a good first step.

The series as a whole is a migration compat break for the machines
involved: mps2-an385, mps2-an386, mps2-an500, mps2-an511, mps2-an505,
mps2-an521, musca-a, musca-b1, lm3s811evb, lm3s6965evb.

Series structure:
 * patches adding new clock and ptimer API functions
 * add tests for the devices
 * add Clock inputs to devices, which do nothing for now
 * wire up the clocks in the code that uses the devices
 * make the devices use the clocks and ignore the frq properties
 * remove the setting of the frq properties in code using the devices
 * remove the frq properties from the devices
The new ptimer and clock functions are probably the most interesting part:
 * ptimer_set_period_from_clock(ptimer, clk, divisor)
   is for setting the period of a ptimer directly from a Clock (possibly
   accounting for the frequency being divided by some integer first) --
   this avoids possible rounding errors if we went via ptimer_set_period()
   or ptimer_set_freq()
 * clock_has_source()
   returns true if an input Clock has been connected to an output clock;
   this is for devices to be able to check in their realize method that
   a mandatory clock was wired up by the board
(More detailed info and rationale in patches 1 and 2.)

A couple of bits of food-for-thought as a result of working with the
relatively-new Clock APIs:
 * it might be worth thinking about whether we can have a fairly
   lightweight implementation of a clock-divider or clock-multiplier,
   because I feel they are pretty common. (For this series I opted
   just to handle this via the ptimer_set_period_from_clock()
   divisor argumuent.)
 * it feels a little awkward that devices with an input Clock need
   to do ptimer_set_period_from_clock() or similar both in their
   realize method (to cope with fixed-frequency input clocks, because
   the clock callback functions are not called when board setup code
   creates and configures those) and in the clock callback function
   (to cope with variable-frequency clocks)
 * I found it odd that ptimer's period representation is 64.32
   fixedpoint 2^-32 ns units, whereas Clock's is only 32.32
   (so ptimer can handle much larger periods than Clock can.)
   I forget why we didn't go for the same representation in Clock
   as we have for ptimer...
 * there's no MAINTAINERS entry for the Clock framework

I don't think these need to be blockers on this series, though.

-- PMM

Peter Maydell (25):
  ptimer: Add new ptimer_set_period_from_clock() function
  clock: Add new clock_has_source() function
  tests: Add a simple test of the CMSDK APB timer
  tests: Add a simple test of the CMSDK APB watchdog
  tests: Add a simple test of the CMSDK APB dual timer
  hw/timer/cmsdk-apb-timer: Rename CMSDKAPBTIMER struct to CMSDKAPBTimer
  hw/timer/cmsdk-apb-timer: Add Clock input
  hw/timer/cmsdk-apb-dualtimer: Add Clock input
  hw/watchdog/cmsdk-apb-watchdog: Add Clock input
  hw/arm/armsse: Rename "MAINCLK" property to "MAINCLK_FRQ"
  hw/arm/armsse: Wire up clocks
  hw/arm/mps2: Inline CMSDK_APB_TIMER creation
  hw/arm/mps2: Create and connect SYSCLK Clock
  hw/arm/mps2-tz: Create and connect ARMSSE Clocks
  hw/arm/musca: Create and connect ARMSSE Clocks
  hw/arm/stellaris: Convert SSYS to QOM device
  hw/arm/stellaris: Create Clock input for watchdog
  hw/timer/cmsdk-apb-timer: Convert to use Clock input
  hw/timer/cmsdk-apb-dualtimer: Convert to use Clock input
  hw/watchdog/cmsdk-apb-watchdog: Convert to use Clock input
  tests/qtest/cmsdk-apb-watchdog-test: Test clock changes
  hw/arm/armsse: Use Clock to set system_clock_scale
  arm: Don't set freq properties on CMSDK timer, dualtimer, watchdog,
  arm: Remove frq properties on CMSDK timer, dualtimer, watchdog, ARMSSE
  hw/arm/stellaris: Remove board-creation reset of STELLARIS_SYS

 docs/devel/clocks.rst                    |  16 +++
 include/hw/arm/armsse.h                  |  14 +-
 include/hw/clock.h                       |  15 ++
 include/hw/ptimer.h                      |  22 +++
 include/hw/timer/cmsdk-apb-dualtimer.h   |   5 +-
 include/hw/timer/cmsdk-apb-timer.h       |  34 ++---
 include/hw/watchdog/cmsdk-apb-watchdog.h |   5 +-
 include/qemu/typedefs.h                  |   1 +
 hw/arm/armsse.c                          |  47 +++++--
 hw/arm/mps2-tz.c                         |  14 +-
 hw/arm/mps2.c                            |  28 +++-
 hw/arm/musca.c                           |  13 +-
 hw/arm/stellaris.c                       | 170 +++++++++++++++++------
 hw/core/ptimer.c                         |  34 +++++
 hw/timer/cmsdk-apb-dualtimer.c           |  53 +++++--
 hw/timer/cmsdk-apb-timer.c               |  55 ++++----
 hw/watchdog/cmsdk-apb-watchdog.c         |  29 ++--
 tests/qtest/cmsdk-apb-dualtimer-test.c   | 131 +++++++++++++++++
 tests/qtest/cmsdk-apb-timer-test.c       |  76 ++++++++++
 tests/qtest/cmsdk-apb-watchdog-test.c    | 132 ++++++++++++++++++
 MAINTAINERS                              |   3 +
 tests/qtest/meson.build                  |   3 +
 22 files changed, 758 insertions(+), 142 deletions(-)
 create mode 100644 tests/qtest/cmsdk-apb-dualtimer-test.c
 create mode 100644 tests/qtest/cmsdk-apb-timer-test.c
 create mode 100644 tests/qtest/cmsdk-apb-watchdog-test.c


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