From: "Arnd Bergmann" <arnd@arndb.de>
To: "Yann Sionneau" <ysionneau@kalrayinc.com>,
"Krzysztof Kozlowski" <krzysztof.kozlowski@linaro.org>,
"Yann Sionneau" <ysionneau@kalray.eu>,
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Cc: "Benjamin Mugnier" <mugnier.benjamin@gmail.com>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
devicetree@vger.kernel.org, linux-mm@kvack.org,
Linux-Arch <linux-arch@vger.kernel.org>,
linux-audit@redhat.com, linux-riscv@lists.infradead.org,
bpf@vger.kernel.org
Subject: Re: [RFC PATCH v2 31/31] kvx: Add IPI driver
Date: Wed, 31 Jan 2024 11:28:57 +0100 [thread overview]
Message-ID: <1036060c-25dd-439b-b081-893d0cb000f6@app.fastmail.com> (raw)
In-Reply-To: <269edff0-d989-4ac8-b0c3-bce31283806b@kalrayinc.com>
On Wed, Jan 31, 2024, at 10:52, Yann Sionneau wrote:
> On 22/01/2023 12:54, Krzysztof Kozlowski wrote:
>> On 20/01/2023 15:10, Yann Sionneau wrote:
>>> +
>>> +int __init kvx_ipi_ctrl_probe(irqreturn_t (*ipi_irq_handler)(int, void *))
>>> +{
>>> + struct device_node *np;
>>> + int ret;
>>> + unsigned int ipi_irq;
>>> + void __iomem *ipi_base;
>>> +
>>> + np = of_find_compatible_node(NULL, NULL, "kalray,kvx-ipi-ctrl");
>> Nope, big no.
>>
>> Drivers go to drivers, not to arch code. Use proper driver infrastructure.
> Thank you for your review.
>
> It raises questions on our side about how to handle this change.
>
> First let me describe the hardware:
>
> The coolidge ipi controller device handles IPI communication between cpus
> inside a cluster.
>
> Each cpu has 8 of its dedicated irq lines (24 to 31) hard-wired to the ipi.
> The ipi controller has 8 sets of 2 registers:
> - a 17-bit "interrupt" register
> - a 17-bit "mask" register
>
> Each couple of register is dedicated to 1 of the 8 irqlines.
> Each of the 17 bits of interrupt/mask register
> identifies a cpu (cores 0 to 15 + secure_core).
> Writing bit i in interrupt register sends an irq to cpu i, according to the mask
> in mask register.
> Writing in interrupt/mask register couple N targets irq line N of the core.
>
> - Ipi generates an interrupt to the cpu when message is ready.
> - Messages are delivered via Axi.
> - Ipi does not have any interrupt input lines.
>
>
> +---------------+ irq axi_w
> | | i |<--/--- ipi <------
> | CPU | n | x8
> | core0 | t |
> | | c | irq irq msi
> | | t |<--/--- apic <----- mbox <-------
> | | l | x4
> +---------------+
> with intctl = core-irq controller
>
>
> We analyzed how other Linux ports are handling this situation (IPI) and
> here are several possible solutions:
>
> 1/ put everything in smp.c like what longarch is doing.
> * Except that IPI in longarch seems to involve writing to a special
> purpose CPU register and not doing a memory mapped write like kvx.
>
> 2/ write a device driver in drivers/xxx/ with the content from ipi.c
> * the probe would just ioremap the reg from DT and register the irq
> using request_percpu_irq()
> * it would export a function "kvx_ipi_send()" that would directly be
> called by smp.c
> * Question : where would this driver be placed in drivers/ ?
> drivers/irqchip/ ? Even if this is not per-se an interrupt-controller
> driver?
This looks like it's close enough to the irqchip driver
that you can just have it in the same file as the 'intctl'
portion.
Top-level irqchip implementations tend to be rather architecture
specific, as does the IPI mechanism. Depending on the register
layout, I think you can have a single devicetree node for
the combination of the core-irq (for managing your
own interrupts) and the ipi (for receiving interrupts from
others), and then have a driver in drivers/irqchip to
deal with both. For the ipi mechanism, trying to abstract
it too much generally makes it too slow, so I would not
go through a nested irqchip or a mailbox driver etc.
I don't know what the 'apic' in your diagram is, so that
would be either a nested irqchip or could be part of
the same driver as well.
Arnd
next prev parent reply other threads:[~2024-01-31 10:29 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-20 14:09 [RFC PATCH v2 00/31] Upstream kvx Linux port Yann Sionneau
2023-01-20 14:09 ` [RFC PATCH v2 01/31] Documentation: kvx: Add basic documentation Yann Sionneau
2023-01-22 9:02 ` Bagas Sanjaya
2023-01-25 18:28 ` Jules Maselbas
2023-01-26 2:23 ` Bagas Sanjaya
2023-01-22 15:02 ` Mike Rapoport
2023-01-20 14:09 ` [RFC PATCH v2 02/31] Documentation: Add binding for kalray,kv3-1-core-intc Yann Sionneau
2023-01-20 17:28 ` Rob Herring
2023-01-22 11:44 ` Krzysztof Kozlowski
2023-01-26 16:10 ` Jules Maselbas
2023-01-27 8:32 ` Krzysztof Kozlowski
2023-01-20 14:09 ` [RFC PATCH v2 03/31] Documentation: Add binding for kalray,kv3-1-apic-gic Yann Sionneau
2023-01-22 11:47 ` Krzysztof Kozlowski
2023-01-20 14:09 ` [RFC PATCH v2 04/31] Documentation: Add binding for kalray,kv3-1-apic-mailbox Yann Sionneau
2023-01-20 17:28 ` Rob Herring
2023-01-20 14:09 ` [RFC PATCH v2 05/31] Documentation: Add binding for kalray,coolidge-itgen Yann Sionneau
2023-01-22 11:49 ` Krzysztof Kozlowski
2023-01-20 14:09 ` [RFC PATCH v2 06/31] Documentation: Add binding for kalray,kv3-1-ipi-ctrl Yann Sionneau
2023-01-20 17:28 ` Rob Herring
2023-01-22 11:50 ` Krzysztof Kozlowski
2023-01-20 14:09 ` [RFC PATCH v2 07/31] Documentation: Add binding for kalray,kv3-1-pwr-ctrl Yann Sionneau
2023-01-20 17:28 ` Rob Herring
2023-01-22 11:51 ` Krzysztof Kozlowski
2023-01-20 14:09 ` [RFC PATCH v2 08/31] kvx: Add ELF-related definitions Yann Sionneau
2023-01-20 14:09 ` [RFC PATCH v2 09/31] kvx: Add build infrastructure Yann Sionneau
2023-01-20 14:39 ` Arnd Bergmann
2023-01-20 14:53 ` Jules Maselbas
2023-01-20 15:01 ` Arnd Bergmann
2023-01-20 15:03 ` Jules Maselbas
2023-01-20 14:09 ` [RFC PATCH v2 11/31] kvx: Add atomic/locking headers Yann Sionneau
2023-01-20 15:18 ` Mark Rutland
2023-01-26 9:57 ` Jules Maselbas
2023-01-26 11:15 ` Mark Rutland
2023-01-26 11:19 ` Jules Maselbas
2023-01-29 11:50 ` Guo Ren
2023-01-20 14:09 ` [RFC PATCH v2 12/31] kvx: Add other common headers Yann Sionneau
2023-01-20 14:29 ` Jason A. Donenfeld
2023-01-25 21:55 ` Jules Maselbas
2023-01-20 14:09 ` [RFC PATCH v2 13/31] kvx: Add boot and setup routines Yann Sionneau
2023-01-20 14:09 ` [RFC PATCH v2 14/31] kvx: Add exception/interrupt handling Yann Sionneau
2023-01-20 14:09 ` [RFC PATCH v2 15/31] irqchip: Add irq-kvx-apic-gic driver Yann Sionneau
2023-01-20 14:09 ` [RFC PATCH v2 16/31] irqchip: Add irq-kvx-itgen driver Yann Sionneau
2023-01-20 14:09 ` [RFC PATCH v2 17/31] irqchip: Add irq-kvx-apic-mailbox driver Yann Sionneau
2023-01-20 14:09 ` [RFC PATCH v2 18/31] irqchip: Add kvx-core-intc core interupt controller driver Yann Sionneau
2023-01-20 14:09 ` [RFC PATCH v2 19/31] kvx: Add process management Yann Sionneau
2023-01-20 14:09 ` [RFC PATCH v2 21/31] kvx: Add system call support Yann Sionneau
2023-01-20 14:09 ` [RFC PATCH v2 22/31] kvx: Add signal handling support Yann Sionneau
2023-01-20 14:09 ` [RFC PATCH v2 23/31] kvx: Add ELF relocations and module support Yann Sionneau
2023-01-20 14:09 ` [RFC PATCH v2 24/31] kvx: Add misc common routines Yann Sionneau
2023-01-20 14:09 ` [RFC PATCH v2 25/31] kvx: Add some library functions Yann Sionneau
2023-01-20 14:09 ` [RFC PATCH v2 26/31] kvx: Add multi-processor (SMP) support Yann Sionneau
2023-01-20 14:09 ` [RFC PATCH v2 27/31] kvx: Add kvx default config file Yann Sionneau
2023-01-22 11:58 ` Krzysztof Kozlowski
2023-01-20 14:09 ` [RFC PATCH v2 28/31] kvx: Add debugging related support Yann Sionneau
2023-01-20 14:10 ` [RFC PATCH v2 29/31] kvx: Add support for cpuinfo Yann Sionneau
2023-01-22 11:57 ` Krzysztof Kozlowski
2023-01-20 14:10 ` [RFC PATCH v2 30/31] kvx: Add power controller driver Yann Sionneau
2023-01-22 11:54 ` Krzysztof Kozlowski
2024-04-15 14:08 ` Yann Sionneau
2024-04-15 15:30 ` Arnd Bergmann
2024-04-17 19:20 ` Krzysztof Kozlowski
2023-01-20 14:10 ` [RFC PATCH v2 31/31] kvx: Add IPI driver Yann Sionneau
2023-01-22 11:54 ` Krzysztof Kozlowski
2024-01-31 9:52 ` Yann Sionneau
2024-01-31 10:12 ` Krzysztof Kozlowski
2024-01-31 10:28 ` Arnd Bergmann [this message]
[not found] ` <20230120141002.2442-21-ysionneau@kalray.eu>
2023-01-22 16:09 ` [RFC PATCH v2 20/31] kvx: Add memory management Mike Rapoport
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