mirror of
https://github.com/xen-project/xen.git
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Ayan Kumar Halder
fcde5e0de8
The OFT tags for the design requirements are updated.
Fixes: b9f9b39645 ("docs: fusa: Add dom0less domain configuration requirements")
Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@amd.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
146 lines
3.3 KiB
ReStructuredText
146 lines
3.3 KiB
ReStructuredText
.. SPDX-License-Identifier: CC-BY-4.0
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Generic Timer
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=============
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The following are the requirements related to ARM Generic Timer [1] interface
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exposed by Xen to Arm64 domains.
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Probe the Generic Timer device tree node from a domain
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------------------------------------------------------
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`XenSwdgn~arm64_generic_timer_probe_dt~1`
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Description:
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Xen shall generate a device tree node for the Generic Timer (in accordance to
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ARM architected timer device tree binding [2]) in the domain device tree.
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Rationale:
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Comments:
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Domains can detect the presence of the Generic Timer device tree node.
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Covers:
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- `XenProd~arm64_emulated_timer~1`
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Read system counter frequency
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-----------------------------
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`XenSwdgn~arm64_generic_timer_read_freq~1`
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Description:
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Xen shall expose the frequency of the system counter to the domains in
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CNTFRQ_EL0 register.
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Rationale:
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Comments:
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Covers:
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- `XenProd~arm64_emulated_timer~1`
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Access CNTKCTL_EL1 system register from a domain
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------------------------------------------------
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`XenSwdgn~arm64_generic_timer_access_cntkctlel1~1`
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Description:
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Xen shall expose Counter-timer Kernel Control register (CNTKCTL_EL1) to the
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domains.
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Rationale:
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Comments:
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Covers:
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- `XenProd~arm64_emulated_timer~1`
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Access virtual timer from a domain
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----------------------------------
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`XenSwdgn~arm64_generic_timer_access_virtual_timer~1`
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Description:
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Xen shall expose the virtual timer registers (CNTVCT_EL0, CNTV_CTL_EL0,
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CNTV_CVAL_EL0, CNTV_TVAL_EL0) to the domains.
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Rationale:
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Comments:
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Covers:
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- `XenProd~arm64_emulated_timer~1`
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Access physical timer from a domain
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-----------------------------------
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`XenSwdgn~arm64_generic_timer_access_physical_timer~1`
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Description:
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Xen shall expose physical timer registers (CNTPCT_EL0, CNTP_CTL_EL0,
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CNTP_CVAL_EL0, CNTP_TVAL_EL0) to the domains.
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Rationale:
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Comments:
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Covers:
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- `XenProd~arm64_emulated_timer~1`
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Trigger the virtual timer interrupt from a domain
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-------------------------------------------------
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`XenSwdgn~arm64_generic_timer_trigger_virtual_interrupt~1`
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Description:
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Xen shall generate virtual timer interrupts to domains when the virtual timer
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condition is met.
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Rationale:
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Comments:
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Covers:
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- `XenProd~arm64_emulated_timer~1`
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Trigger the physical timer interrupt from a domain
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--------------------------------------------------
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`XenSwdgn~arm64_generic_timer_trigger_physical_interrupt~1`
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Description:
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Xen shall generate physical timer interrupts to domains when the physical timer
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condition is met.
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Rationale:
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Comments:
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Covers:
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- `XenProd~arm64_emulated_timer~1`
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Assumption of Use on the Platform
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=================================
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Expose system timer frequency via register
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------------------------------------------
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`XenSwdgn~arm64_generic_timer_plat_program_cntfrq_el0~1`
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Description:
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CNTFRQ_EL0 register shall be programmed with the value of the system timer
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frequency.
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Rationale:
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Xen reads the CNTFRQ_EL0 register to get the value of system timer frequency.
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Comments:
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While there is a provision to get this value by reading the "clock-frequency"
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dt property [2], the use of this property is strongly discouraged.
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Covers:
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- `XenProd~arm64_emulated_timer~1`
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[1] Arm Architecture Reference Manual for A-profile architecture, Chapter 11
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[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/timer/arm,arch_timer.yaml
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