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[Qemu-devel] [PULL 04/12] arm: Move system_clock_scale to armv7m_systick
From: |
Peter Maydell |
Subject: |
[Qemu-devel] [PULL 04/12] arm: Move system_clock_scale to armv7m_systick.h |
Date: |
Thu, 23 May 2019 15:23:49 +0100 |
The system_clock_scale global is used only by the armv7m systick
device; move the extern declaration to the armv7m_systick.h header,
and expand the comment to explain what it is and that it should
ideally be replaced with a different approach.
Signed-off-by: Peter Maydell <address@hidden>
Reviewed-by: Philippe Mathieu-Daudé <address@hidden>
Tested-by: Philippe Mathieu-Daudé <address@hidden>
Message-id: address@hidden
---
include/hw/arm/arm.h | 4 ----
include/hw/timer/armv7m_systick.h | 22 ++++++++++++++++++++++
2 files changed, 22 insertions(+), 4 deletions(-)
diff --git a/include/hw/arm/arm.h b/include/hw/arm/arm.h
index ffed39252d8..ba3a9b41422 100644
--- a/include/hw/arm/arm.h
+++ b/include/hw/arm/arm.h
@@ -167,8 +167,4 @@ void arm_write_secure_board_setup_dummy_smc(ARMCPU *cpu,
const struct arm_boot_info *info,
hwaddr mvbar_addr);
-/* Multiplication factor to convert from system clock ticks to qemu timer
- ticks. */
-extern int system_clock_scale;
-
#endif /* HW_ARM_H */
diff --git a/include/hw/timer/armv7m_systick.h
b/include/hw/timer/armv7m_systick.h
index cca04defd8e..25e5ceacc85 100644
--- a/include/hw/timer/armv7m_systick.h
+++ b/include/hw/timer/armv7m_systick.h
@@ -31,4 +31,26 @@ typedef struct SysTickState {
qemu_irq irq;
} SysTickState;
+/*
+ * 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
--
2.20.1
- [Qemu-devel] [PULL 00/12] target-arm queue, Peter Maydell, 2019/05/23
- [Qemu-devel] [PULL 01/12] target/arm: Use extract2 for EXTR, Peter Maydell, 2019/05/23
- [Qemu-devel] [PULL 02/12] target/arm: Simplify BFXIL expansion, Peter Maydell, 2019/05/23
- [Qemu-devel] [PULL 03/12] target/arm: Fix vector operation segfault, Peter Maydell, 2019/05/23
- [Qemu-devel] [PULL 04/12] arm: Move system_clock_scale to armv7m_systick.h,
Peter Maydell <=
- [Qemu-devel] [PULL 05/12] arm: Remove unnecessary includes of hw/arm/arm.h, Peter Maydell, 2019/05/23
- [Qemu-devel] [PULL 11/12] hw/arm/exynos4210: Add DMA support for the Exynos4210, Peter Maydell, 2019/05/23
- [Qemu-devel] [PULL 07/12] hw/intc/arm_gicv3: Fix write of ICH_VMCR_EL2.{VBPR0, VBPR1}, Peter Maydell, 2019/05/23
- [Qemu-devel] [PULL 12/12] hw/arm/exynos4210: QOM'ify the Exynos4210 SoC, Peter Maydell, 2019/05/23
- [Qemu-devel] [PULL 08/12] hw/intc/arm_gicv3: Fix writes to ICC_CTLR_EL3, Peter Maydell, 2019/05/23
- [Qemu-devel] [PULL 10/12] hw/arm/exynos4: Use the IEC binary prefix definitions, Peter Maydell, 2019/05/23
- [Qemu-devel] [PULL 09/12] hw/arm/exynos4: Remove unuseful debug code, Peter Maydell, 2019/05/23
- [Qemu-devel] [PULL 06/12] arm: Rename hw/arm/arm.h to hw/arm/boot.h, Peter Maydell, 2019/05/23
- Re: [Qemu-devel] [PULL 00/12] target-arm queue, Peter Maydell, 2019/05/24