On Thu, Aug 12, 2021 at 7:36 PM Peter Maydell <peter.mayd...@linaro.org> wrote:
>
> The v7M systick timer can be programmed to run from either of
> two clocks:
> * an "external reference clock" (when SYST_CSR.CLKSOURCE == 0)
> * the main CPU clock (when SYST_CSR.CLKSOURCE == 1)
>
> Our implementation currently hardwires the external reference clock
> to be 1MHz, and allows boards to set the main CPU clock frequency via
> the global 'system_clock_scale'. (Most boards set that to a constant
> value; the Stellaris boards allow the guest to reprogram it via the
> board-specific RCC registers).
>
> As the first step in converting this to use the Clock infrastructure,
> add input clocks to the systick device for the reference clock and
> the CPU clock. The device implementation ignores them; once we have
> made all the users of the device correctly wire up the new Clocks we
> will switch the implementation to use them and ignore the old
> system_clock_scale.
>
> This is a migration compat break for all M-profile boards, because of
> the addition of the new clock objects to the vmstate struct.
>
> Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
Reviewed-by: Alistair Francis <alistair.fran...@wdc.com>
Alistair
> ---
> include/hw/timer/armv7m_systick.h | 7 +++++++
> hw/timer/armv7m_systick.c | 10 ++++++++--
> 2 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/include/hw/timer/armv7m_systick.h
> b/include/hw/timer/armv7m_systick.h
> index 685fc5bc0d7..38adf8d274e 100644
> --- a/include/hw/timer/armv7m_systick.h
> +++ b/include/hw/timer/armv7m_systick.h
> @@ -15,6 +15,7 @@
> #include "hw/sysbus.h"
> #include "qom/object.h"
> #include "hw/ptimer.h"
> +#include "hw/clock.h"
>
> #define TYPE_SYSTICK "armv7m_systick"
>
> @@ -25,6 +26,10 @@ OBJECT_DECLARE_SIMPLE_TYPE(SysTickState, SYSTICK)
> * + sysbus MMIO region 0 is the register interface (covering
> * the registers which are mapped at address 0xE000E010)
> * + sysbus IRQ 0 is the interrupt line to the NVIC
> + * + Clock input "refclk" is the external reference clock
> + * (used when SYST_CSR.CLKSOURCE == 0)
> + * + Clock input "cpuclk" is the main CPU clock
> + * (used when SYST_CSR.CLKSOURCE == 1)
> */
>
> struct SysTickState {
> @@ -38,6 +43,8 @@ struct SysTickState {
> ptimer_state *ptimer;
> MemoryRegion iomem;
> qemu_irq irq;
> + Clock *refclk;
> + Clock *cpuclk;
> };
>
> /*
> diff --git a/hw/timer/armv7m_systick.c b/hw/timer/armv7m_systick.c
> index 2f192011eb0..e43f74114e8 100644
> --- a/hw/timer/armv7m_systick.c
> +++ b/hw/timer/armv7m_systick.c
> @@ -14,6 +14,7 @@
> #include "migration/vmstate.h"
> #include "hw/irq.h"
> #include "hw/sysbus.h"
> +#include "hw/qdev-clock.h"
> #include "qemu/timer.h"
> #include "qemu/log.h"
> #include "qemu/module.h"
> @@ -201,6 +202,9 @@ static void systick_instance_init(Object *obj)
> memory_region_init_io(&s->iomem, obj, &systick_ops, s, "systick", 0xe0);
> sysbus_init_mmio(sbd, &s->iomem);
> sysbus_init_irq(sbd, &s->irq);
> +
> + s->refclk = qdev_init_clock_in(DEVICE(obj), "refclk", NULL, NULL, 0);
> + s->cpuclk = qdev_init_clock_in(DEVICE(obj), "cpuclk", NULL, NULL, 0);
> }
>
> static void systick_realize(DeviceState *dev, Error **errp)
> @@ -215,9 +219,11 @@ static void systick_realize(DeviceState *dev, Error
> **errp)
>
> static const VMStateDescription vmstate_systick = {
> .name = "armv7m_systick",
> - .version_id = 2,
> - .minimum_version_id = 2,
> + .version_id = 3,
> + .minimum_version_id = 3,
> .fields = (VMStateField[]) {
> + VMSTATE_CLOCK(refclk, SysTickState),
> + VMSTATE_CLOCK(cpuclk, SysTickState),
> VMSTATE_UINT32(control, SysTickState),
> VMSTATE_INT64(tick, SysTickState),
> VMSTATE_PTIMER(ptimer, SysTickState),
> --
> 2.20.1
>
>
