From: r.sricharan@ti•com (Sricharan R)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 1/3] misc: Add crossbar driver
Date: Thu, 22 Aug 2013 17:03:10 +0530 [thread overview]
Message-ID: <5215F6F6.9060703@ti.com> (raw)
In-Reply-To: <CACRpkdagSHxzV3=427O9iftNxM+N=w9aPds=iDvGQPoG3H-cWw@mail.gmail.com>
Hi Linus,
On Thursday 22 August 2013 02:40 AM, Linus Walleij wrote:
> On Thu, Aug 15, 2013 at 11:14 PM, Santosh Shilimkar
> <santosh.shilimkar@ti•com> wrote:
>> On Thursday 15 August 2013 04:51 PM, Linus Walleij wrote:
> (...)
>>> Sorry I don't understand what thread that is... can you point me there?
>>> My previous statement on this issue what this:
>>> http://marc.info/?l=linux-kernel&m=137442541628641&w=2
> (...)
>>>> I don't see how you can make this happen with an irqchip
>>>> infrastructure.
>>> I think my post above describes this.
>>>
>> Sorry for being dumb but I don't think cascaded irqchip examples
>> like GPIO and cross-bars are same. If you take an example of
>> GPIO irqchip, it always have a physical connection even if it
>> is 1 IRQ line for (32 logical/sparse IRQs). That goes with
>> other MFD examples too.
>>
>> So may be I am still missing something in your proposal.
> Why does it matter if it is a GPIO or MFD or whatever?
> The point is that the IRQ line passes thru something else,
> and this we model as an irqdomain.
>
> Anyway here is a silicon cascaded IRQ chip:
> arch/arm/mach-versatile/core.c
> See versatile_init_irq():
>
> __vic_init(VA_VIC_BASE, IRQ_VIC_START, ~0, 0, np);
> (...)
> fpga_irq_init(VA_SIC_BASE, "SIC", IRQ_SIC_START,
> IRQ_VICSOURCE31, PIC_VALID, np);
>
> The VIC in the versatile has the SIC cascaded from one of
> its IRQ lines. Both the VIC and SIC (fpga IRQ) are
> using irqdomains so the SIC spawns a child irqdomain
> from IRQ 31 (last IRQ) of the VIC.
Ok, this is a typical example of irqchip cascaded.
> The difference with a crossbar is that it can software-config
> which IRQ goes where, and does not have a callback
> to clear interrupts or anything like that, it just passes them
> thru. But it is best modeled as an irqdomain IMO.
We can model crossbar as irqchip and gic as its interrupt parent
and peripherals to have crossbar as interrupt-parent.
peripherals will do request_irq(crossbar_number)
|
|
crossbar_unmask()
|
|
maps crossbar number<-> to interrupt number and
calls request_irq(int_no, crossbar_handler,..)
crossbar_handler(interrupt number)
|
|
get crossbar number from interrupt number
|
|
handle_irq(crossbar_domain(crossbar number))
So this means a extra dummy handler.
Also the concern is by modelling it as irqchip, we will have
to find a different solution for DMA crossbar.
Regards,
Sricharan
next prev parent reply other threads:[~2013-08-22 11:33 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-18 16:43 [PATCH 0/3] Add crossbar driver Sricharan R
2013-07-18 16:43 ` [PATCH 1/3] misc: " Sricharan R
2013-07-18 16:55 ` Joe Perches
2013-07-18 18:25 ` Felipe Balbi
2013-07-21 16:33 ` Linus Walleij
2013-07-18 18:56 ` Nishanth Menon
2013-07-18 23:39 ` Santosh Shilimkar
2013-07-19 0:13 ` Nishanth Menon
2013-07-19 10:48 ` Sricharan R
2013-07-19 7:17 ` Tony Lindgren
2013-07-19 10:48 ` Sricharan R
2013-07-21 16:49 ` Linus Walleij
2013-07-22 12:20 ` Sricharan R
2013-07-22 16:23 ` Santosh Shilimkar
2013-07-24 16:08 ` Nishanth Menon
2013-07-24 16:38 ` Santosh Shilimkar
2013-07-24 16:47 ` Nishanth Menon
2013-07-24 18:43 ` Sricharan R
2013-07-24 18:51 ` Nishanth Menon
2013-07-24 18:59 ` Santosh Shilimkar
2013-08-13 8:10 ` Tony Lindgren
2013-08-13 9:56 ` Sricharan R
2013-08-13 13:29 ` Santosh Shilimkar
2013-08-15 20:01 ` Linus Walleij
2013-08-15 20:26 ` Santosh Shilimkar
2013-08-15 20:51 ` Linus Walleij
2013-08-15 21:14 ` Santosh Shilimkar
2013-08-21 21:10 ` Linus Walleij
2013-08-22 11:33 ` Sricharan R [this message]
2013-08-22 13:45 ` Santosh Shilimkar
2013-08-23 4:47 ` Rajendra Nayak
2013-08-23 6:11 ` Sricharan R
2013-08-23 6:17 ` Rajendra Nayak
2013-08-23 6:36 ` Sekhar Nori
2013-08-23 6:53 ` Sricharan R
2013-08-23 8:14 ` Sekhar Nori
2013-08-23 13:38 ` Santosh Shilimkar
2013-08-23 16:28 ` Sekhar Nori
2013-08-23 19:06 ` Linus Walleij
2013-08-23 19:44 ` Santosh Shilimkar
2013-08-13 13:28 ` Santosh Shilimkar
2013-08-14 7:27 ` Tony Lindgren
2013-07-18 16:43 ` [PATCH 2/3] ARM: dts: DRA: Add crossbar device binding Sricharan R
2013-07-18 19:04 ` Nishanth Menon
2013-07-18 16:43 ` [PATCH 3/3] ARM: DRA7xx: Enable crossbar driver for the soc Sricharan R
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5215F6F6.9060703@ti.com \
--to=r.sricharan@ti$(echo .)com \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox