Re: [PATCH for-6.2 25/25] arm: Remove system_clock_scale global

[Alistair Francis]

On Thu, Aug 12, 2021 at 7:52 PM Peter Maydell <peter.maydell@linaro.org> wrote:
>
> All the devices that used to use system_clock_scale have now been
> converted to use Clock inputs instead, so the global is no longer
> needed; remove it and all the code that sets it.
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  include/hw/timer/armv7m_systick.h | 22 ----------------------
>  hw/arm/armsse.c                   | 17 +----------------
>  hw/arm/mps2.c                     |  2 --
>  hw/arm/msf2-soc.c                 |  2 --
>  hw/arm/netduino2.c                |  2 --
>  hw/arm/netduinoplus2.c            |  2 --
>  hw/arm/nrf51_soc.c                |  2 --
>  hw/arm/stellaris.c                |  7 ++++---
>  hw/arm/stm32vldiscovery.c         |  2 --
>  hw/timer/armv7m_systick.c         |  2 --
>  10 files changed, 5 insertions(+), 55 deletions(-)
>
> diff --git a/include/hw/timer/armv7m_systick.h 
> b/include/hw/timer/armv7m_systick.h
> index 38adf8d274e..ee09b138810 100644
> --- a/include/hw/timer/armv7m_systick.h
> +++ b/include/hw/timer/armv7m_systick.h
> @@ -47,26 +47,4 @@ struct SysTickState {
>      Clock *cpuclk;
>  };
>
> -/*
> - * Multiplication factor to convert from system clock ticks to qemu timer
> - * ticks. This should be set (by board code, usually) to a value
> - * equal to NANOSECONDS_PER_SECOND / frq, where frq is the clock frequency
> - * in Hz of the CPU.
> - *
> - * This value is used by the systick device when it is running in
> - * its "use the CPU clock" mode (ie when SYST_CSR.CLKSOURCE == 1) to
> - * set how fast the timer should tick.
> - *
> - * TODO: we should refactor this so that rather than using a global
> - * we use a device property or something similar. This is complicated
> - * because (a) the property would need to be plumbed through from the
> - * board code down through various layers to the systick device
> - * and (b) the property needs to be modifiable after realize, because
> - * the stellaris board uses this to implement the behaviour where the
> - * guest can reprogram the PLL registers to downclock the CPU, and the
> - * systick device needs to react accordingly. Possibly this should
> - * be deferred until we have a good API for modelling clock trees.
> - */
> -extern int system_clock_scale;
> -
>  #endif
> diff --git a/hw/arm/armsse.c b/hw/arm/armsse.c
> index 70b52c3d4b9..aecdeb9815a 100644
> --- a/hw/arm/armsse.c
> +++ b/hw/arm/armsse.c
> @@ -689,17 +689,6 @@ static void armsse_forward_sec_resp_cfg(ARMSSE *s)
>      qdev_connect_gpio_out(dev_splitter, 2, s->sec_resp_cfg_in);
>  }
>
> -static void armsse_mainclk_update(void *opaque, ClockEvent event)
> -{
> -    ARMSSE *s = ARM_SSE(opaque);
> -
> -    /*
> -     * Set system_clock_scale from our Clock input; this is what
> -     * controls the tick rate of the CPU SysTick timer.
> -     */
> -    system_clock_scale = clock_ticks_to_ns(s->mainclk, 1);
> -}
> -
>  static void armsse_init(Object *obj)
>  {
>      ARMSSE *s = ARM_SSE(obj);
> @@ -711,8 +700,7 @@ static void armsse_init(Object *obj)
>      assert(info->sram_banks <= MAX_SRAM_BANKS);
>      assert(info->num_cpus <= SSE_MAX_CPUS);
>
> -    s->mainclk = qdev_init_clock_in(DEVICE(s), "MAINCLK",
> -                                    armsse_mainclk_update, s, ClockUpdate);
> +    s->mainclk = qdev_init_clock_in(DEVICE(s), "MAINCLK", NULL, NULL, 0);
>      s->s32kclk = qdev_init_clock_in(DEVICE(s), "S32KCLK", NULL, NULL, 0);
>
>      memory_region_init(&s->container, obj, "armsse-container", UINT64_MAX);
> @@ -1654,9 +1642,6 @@ static void armsse_realize(DeviceState *dev, Error 
> **errp)
>       * devices in the ARMSSE.
>       */
>      sysbus_init_mmio(SYS_BUS_DEVICE(s), &s->container);
> -
> -    /* Set initial system_clock_scale from MAINCLK */
> -    armsse_mainclk_update(s, ClockUpdate);
>  }
>
>  static void armsse_idau_check(IDAUInterface *ii, uint32_t address,
> diff --git a/hw/arm/mps2.c b/hw/arm/mps2.c
> index 3671f49ad7b..4634aa1a1ca 100644
> --- a/hw/arm/mps2.c
> +++ b/hw/arm/mps2.c
> @@ -439,8 +439,6 @@ static void mps2_common_init(MachineState *machine)
>                   qdev_get_gpio_in(armv7m,
>                                    mmc->fpga_type == FPGA_AN511 ? 47 : 13));
>
> -    system_clock_scale = NANOSECONDS_PER_SECOND / SYSCLK_FRQ;
> -
>      armv7m_load_kernel(ARM_CPU(first_cpu), machine->kernel_filename,
>                         0x400000);
>  }
> diff --git a/hw/arm/msf2-soc.c b/hw/arm/msf2-soc.c
> index dbc6d936a76..b5fe9f364d5 100644
> --- a/hw/arm/msf2-soc.c
> +++ b/hw/arm/msf2-soc.c
> @@ -144,8 +144,6 @@ static void m2sxxx_soc_realize(DeviceState *dev_soc, 
> Error **errp)
>          return;
>      }
>
> -    system_clock_scale = clock_ticks_to_ns(s->m3clk, 1);
> -
>      for (i = 0; i < MSF2_NUM_UARTS; i++) {
>          if (serial_hd(i)) {
>              serial_mm_init(get_system_memory(), uart_addr[i], 2,
> diff --git a/hw/arm/netduino2.c b/hw/arm/netduino2.c
> index b5c0ba23ee5..3365da11bf7 100644
> --- a/hw/arm/netduino2.c
> +++ b/hw/arm/netduino2.c
> @@ -39,8 +39,6 @@ static void netduino2_init(MachineState *machine)
>      DeviceState *dev;
>      Clock *sysclk;
>
> -    system_clock_scale = NANOSECONDS_PER_SECOND / SYSCLK_FRQ;
> -
>      /* This clock doesn't need migration because it is fixed-frequency */
>      sysclk = clock_new(OBJECT(machine), "SYSCLK");
>      clock_set_hz(sysclk, SYSCLK_FRQ);
> diff --git a/hw/arm/netduinoplus2.c b/hw/arm/netduinoplus2.c
> index a5a8999cc8c..76cea8e4891 100644
> --- a/hw/arm/netduinoplus2.c
> +++ b/hw/arm/netduinoplus2.c
> @@ -39,8 +39,6 @@ static void netduinoplus2_init(MachineState *machine)
>      DeviceState *dev;
>      Clock *sysclk;
>
> -    system_clock_scale = NANOSECONDS_PER_SECOND / SYSCLK_FRQ;
> -
>      /* This clock doesn't need migration because it is fixed-frequency */
>      sysclk = clock_new(OBJECT(machine), "SYSCLK");
>      clock_set_hz(sysclk, SYSCLK_FRQ);
> diff --git a/hw/arm/nrf51_soc.c b/hw/arm/nrf51_soc.c
> index e3e849a32b1..34da0d62f00 100644
> --- a/hw/arm/nrf51_soc.c
> +++ b/hw/arm/nrf51_soc.c
> @@ -84,8 +84,6 @@ static void nrf51_soc_realize(DeviceState *dev_soc, Error 
> **errp)
>       * will always provide one).
>       */
>
> -    system_clock_scale = NANOSECONDS_PER_SECOND / HCLK_FRQ;
> -
>      object_property_set_link(OBJECT(&s->cpu), "memory", 
> OBJECT(&s->container),
>                               &error_abort);
>      if (!sysbus_realize(SYS_BUS_DEVICE(&s->cpu), errp)) {
> diff --git a/hw/arm/stellaris.c b/hw/arm/stellaris.c
> index 3e7d1dabad1..78827ace6b8 100644
> --- a/hw/arm/stellaris.c
> +++ b/hw/arm/stellaris.c
> @@ -263,17 +263,18 @@ static bool ssys_use_rcc2(ssys_state *s)
>   */
>  static void ssys_calculate_system_clock(ssys_state *s, bool propagate_clock)
>  {
> +    int period_ns;
>      /*
>       * SYSDIV field specifies divisor: 0 == /1, 1 == /2, etc.  Input
>       * clock is 200MHz, which is a period of 5 ns. Dividing the clock
>       * frequency by X is the same as multiplying the period by X.
>       */
>      if (ssys_use_rcc2(s)) {
> -        system_clock_scale = 5 * (((s->rcc2 >> 23) & 0x3f) + 1);
> +        period_ns = 5 * (((s->rcc2 >> 23) & 0x3f) + 1);
>      } else {
> -        system_clock_scale = 5 * (((s->rcc >> 23) & 0xf) + 1);
> +        period_ns = 5 * (((s->rcc >> 23) & 0xf) + 1);
>      }
> -    clock_set_ns(s->sysclk, system_clock_scale);
> +    clock_set_ns(s->sysclk, period_ns);
>      if (propagate_clock) {
>          clock_propagate(s->sysclk);
>      }
> diff --git a/hw/arm/stm32vldiscovery.c b/hw/arm/stm32vldiscovery.c
> index 9b79004703b..04036da3ee0 100644
> --- a/hw/arm/stm32vldiscovery.c
> +++ b/hw/arm/stm32vldiscovery.c
> @@ -42,8 +42,6 @@ static void stm32vldiscovery_init(MachineState *machine)
>      DeviceState *dev;
>      Clock *sysclk;
>
> -    system_clock_scale = NANOSECONDS_PER_SECOND / SYSCLK_FRQ;
> -
>      /* This clock doesn't need migration because it is fixed-frequency */
>      sysclk = clock_new(OBJECT(machine), "SYSCLK");
>      clock_set_hz(sysclk, SYSCLK_FRQ);
> diff --git a/hw/timer/armv7m_systick.c b/hw/timer/armv7m_systick.c
> index 39cca206cfd..9f92830968b 100644
> --- a/hw/timer/armv7m_systick.c
> +++ b/hw/timer/armv7m_systick.c
> @@ -29,8 +29,6 @@
>  #define SYSCALIB_NOREF (1U << 31)
>  #define SYSCALIB_SKEW (1U << 30)
>
> -int system_clock_scale;
> -
>  static void systick_set_period_from_clock(SysTickState *s)
>  {
>      /*
> --
> 2.20.1
>
>