From: Peter Maydell <peter.maydell@linaro.org>
To: "Marc-André Lureau" <marcandre.lureau@redhat.com>
Cc: "Corey Minyard" <cminyard@mvista.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
"Jason Wang" <jasowang@redhat.com>,
"Mark Cave-Ayland" <mark.cave-ayland@ilande.co.uk>,
"QEMU Developers" <qemu-devel@nongnu.org>,
"KONRAD Frederic" <frederic.konrad@adacore.com>,
"Edgar E. Iglesias" <edgar.iglesias@gmail.com>,
"Paul Burton" <pburton@wavecomp.com>,
"Magnus Damm" <magnus.damm@gmail.com>,
"Hervé Poussineau" <hpoussin@reactos.org>,
"Artyom Tarasenko" <atar4qemu@gmail.com>,
"Eduardo Habkost" <ehabkost@redhat.com>,
"Fabien Chouteau" <chouteau@adacore.com>,
qemu-arm <qemu-arm@nongnu.org>,
"Richard Henderson" <rth@twiddle.net>,
"Daniel P. Berrangé" <berrange@redhat.com>,
qemu-ppc <qemu-ppc@nongnu.org>,
"Aleksandar Markovic" <amarkovic@wavecomp.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Aurelien Jarno" <aurelien@aurel32.net>
Subject: Re: [PATCH v3 14/33] serial-mm: add "regshift" property
Date: Wed, 20 Nov 2019 10:43:41 +0000 [thread overview]
Message-ID: <CAFEAcA90uuQnWXjq=1RjiU5949vxaSuuy7EPFGjMJjpqmY7wMg@mail.gmail.com> (raw)
In-Reply-To: <CAMxuvayTGh6d5H_JXnKRoG7E1MeY-dsw5XqSeR59fdM7njPVeQ@mail.gmail.com>
On Wed, 20 Nov 2019 at 07:54, Marc-André Lureau
<marcandre.lureau@redhat.com> wrote:
>
> Hi
>
> On Mon, Nov 18, 2019 at 6:54 PM Peter Maydell <peter.maydell@linaro.org> wrote:
> >
> > On Wed, 23 Oct 2019 at 18:34, Marc-André Lureau
> > <marcandre.lureau@redhat.com> wrote:
> > > +static Property serial_mm_properties[] = {
> > > + DEFINE_PROP_UINT8("regshift", SerialMM, regshift, 0),
> >
> > This could use a comment describing what the property does.
>
> "Set the register shift value"? Half-kidding, do you have better
> comment to make? Otherwise, it's probably not worth.
>
> From what I understand, it's just applying a shift on the IO addr,
> probably for alignment/access arch-specific reasons. You probably know
> better than me ;)
What this is doing is defining the spacing between adjacent
registers. Some MMIO-based 16550 implementations have the registers
at byte offsets from each other (that's regshift 0). Some have
them at halfword offsets (regshift 1); and some use 4-byte
offsets (regshift 2). Something like this will do:
/*
* Set the spacing between adjacent memory-mapped UART registers.
* Each register will be at (1 << regshift) bytes after the previous one.
*/
(basically the comment bridges the gap between what I know as
somebody trying to use the 16550 model, ie the behaviour of
the hardware I'm trying to model, and what I need to do to configure
the QEMU code to give that behaviour.)
thanks
-- PMM
next prev parent reply other threads:[~2019-11-20 10:45 UTC|newest]
Thread overview: 99+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-23 17:31 [PATCH v3 00/33] Clean-ups: qom-ify serial and remove QDEV_PROP_PTR Marc-André Lureau
2019-10-23 17:31 ` [PATCH v3 01/33] qdev: remove unused qdev_prop_int64 Marc-André Lureau
2019-11-18 14:01 ` Peter Maydell
2019-11-20 3:36 ` Marc-André Lureau
2019-10-23 17:31 ` [PATCH v3 02/33] sysbus: remove unused sysbus_try_create* Marc-André Lureau
2019-10-23 22:35 ` Philippe Mathieu-Daudé
2019-11-18 14:02 ` Peter Maydell
2019-10-23 17:31 ` [PATCH v3 03/33] sysbus: remove outdated comment Marc-André Lureau
2019-10-23 22:36 ` Philippe Mathieu-Daudé
2019-10-23 17:31 ` [PATCH v3 04/33] chardev: generate an internal id when none given Marc-André Lureau
2019-11-18 14:12 ` Peter Maydell
2019-11-18 18:54 ` Marc-André Lureau
2019-10-23 17:31 ` [PATCH v3 05/33] serial-pci-multi: factor out multi_serial_get_nr_ports Marc-André Lureau
2019-10-23 22:41 ` Philippe Mathieu-Daudé
2019-10-24 9:59 ` Marc-André Lureau
2019-10-23 17:31 ` [PATCH v3 06/33] serial: initial qom-ification Marc-André Lureau
2019-10-24 8:48 ` Marc-André Lureau
2019-10-23 17:31 ` [PATCH v3 07/33] serial: register vmsd with DeviceClass Marc-André Lureau
2019-11-18 14:21 ` Peter Maydell
2019-11-19 10:22 ` Marc-André Lureau
2019-11-19 10:33 ` Peter Maydell
2019-11-19 11:57 ` Marc-André Lureau
2019-11-20 18:54 ` Dr. David Alan Gilbert
2019-11-21 6:49 ` Marc-André Lureau
2019-10-23 17:31 ` [PATCH v3 08/33] serial: add "chardev" property Marc-André Lureau
2019-10-23 22:39 ` Philippe Mathieu-Daudé
2019-11-18 14:23 ` Peter Maydell
2019-10-23 17:31 ` [PATCH v3 09/33] serial: add "baudbase" property Marc-André Lureau
2019-10-23 22:40 ` Philippe Mathieu-Daudé
2019-11-18 14:26 ` Peter Maydell
2019-10-23 17:31 ` [PATCH v3 10/33] serial: add "instance-id" property Marc-André Lureau
2019-11-18 14:29 ` Peter Maydell
2019-11-19 10:32 ` Marc-André Lureau
2019-11-20 9:06 ` Marc-André Lureau
2019-10-23 17:31 ` [PATCH v3 11/33] serial: realize the serial device Marc-André Lureau
2019-10-23 17:31 ` [PATCH v3 12/33] serial: replace serial_exit_core() with unrealize Marc-André Lureau
2019-11-18 14:32 ` Peter Maydell
2019-11-20 12:32 ` Philippe Mathieu-Daudé
2019-10-23 17:31 ` [PATCH v3 13/33] serial: start making SerialMM a sysbus device Marc-André Lureau
2019-11-18 14:43 ` Peter Maydell
2019-11-20 7:34 ` Marc-André Lureau
2019-11-20 10:36 ` Peter Maydell
2019-11-20 10:40 ` Marc-André Lureau
2019-11-20 10:58 ` Peter Maydell
2019-11-20 11:03 ` Marc-André Lureau
2019-10-23 17:31 ` [PATCH v3 14/33] serial-mm: add "regshift" property Marc-André Lureau
2019-11-18 14:54 ` Peter Maydell
2019-11-20 7:53 ` Marc-André Lureau
2019-11-20 10:43 ` Peter Maydell [this message]
2019-10-23 17:31 ` [PATCH v3 15/33] serial-mm: add endianness property Marc-André Lureau
2019-11-18 15:02 ` Peter Maydell
2019-11-18 15:07 ` Peter Maydell
2019-11-20 7:59 ` Marc-André Lureau
2019-11-20 12:57 ` Philippe Mathieu-Daudé
2019-10-23 17:31 ` [PATCH v3 16/33] serial-mm: use sysbus facilities Marc-André Lureau
2019-11-18 15:09 ` Peter Maydell
2019-11-20 8:30 ` Marc-André Lureau
2019-11-20 10:46 ` Peter Maydell
2019-10-23 17:31 ` [PATCH v3 17/33] serial: make SerialIO a sysbus device Marc-André Lureau
2019-11-18 15:16 ` Peter Maydell
2019-11-20 8:41 ` Marc-André Lureau
2019-10-23 17:31 ` [PATCH v3 18/33] mips: inline serial_init Marc-André Lureau
2019-11-18 15:24 ` Peter Maydell
2019-11-20 11:14 ` Marc-André Lureau
2019-11-20 0:07 ` Aleksandar Markovic
2019-10-23 17:31 ` [PATCH v3 19/33] sm501: make SerialMM a child, export chardev property Marc-André Lureau
2019-10-23 22:57 ` Philippe Mathieu-Daudé
2019-10-24 10:28 ` Marc-André Lureau
2019-10-23 17:31 ` [PATCH v3 20/33] vmmouse: replace PROP_PTR with PROP_LINK Marc-André Lureau
2019-10-23 22:59 ` Philippe Mathieu-Daudé
2019-10-23 17:31 ` [PATCH v3 21/33] lance: " Marc-André Lureau
2019-10-23 23:00 ` Philippe Mathieu-Daudé
2019-10-24 11:09 ` Marc-André Lureau
2019-10-24 11:47 ` Philippe Mathieu-Daudé
2019-10-24 11:52 ` Peter Maydell
2019-10-24 18:07 ` Eduardo Habkost
2019-10-25 7:31 ` Peter Maydell
2019-10-24 12:25 ` Marc-André Lureau
2019-10-23 17:31 ` [PATCH v3 22/33] etraxfs: remove PROP_PTR usage Marc-André Lureau
2019-11-18 15:28 ` Peter Maydell
2019-10-23 17:31 ` [PATCH v3 23/33] dp8393x: replace PROP_PTR with PROP_LINK Marc-André Lureau
2019-10-23 23:02 ` Philippe Mathieu-Daudé
2019-10-24 11:12 ` Marc-André Lureau
2019-10-24 11:48 ` Philippe Mathieu-Daudé
2019-10-23 17:31 ` [PATCH v3 24/33] leon3: use qemu_irq framework instead of callback as property Marc-André Lureau
2019-11-18 14:15 ` KONRAD Frederic
2019-11-18 15:34 ` Peter Maydell
2019-10-23 17:31 ` [PATCH v3 25/33] sparc: move PIL irq handling to cpu.c Marc-André Lureau
2019-11-18 15:38 ` Peter Maydell
2019-10-23 17:31 ` [PATCH v3 26/33] RFC: mips/cps: fix setting saar property Marc-André Lureau
2019-10-23 17:31 ` [PATCH v3 27/33] cris: improve passing PIC interrupt vector to the CPU Marc-André Lureau
2019-11-18 15:40 ` Peter Maydell
2019-10-23 17:31 ` [PATCH v3 28/33] smbus-eeprom: remove PROP_PTR Marc-André Lureau
2019-10-23 17:31 ` [PATCH v3 29/33] omap-intc: " Marc-André Lureau
2019-10-23 17:31 ` [PATCH v3 30/33] omap-i2c: " Marc-André Lureau
2019-10-23 17:31 ` [PATCH v3 31/33] omap-gpio: " Marc-André Lureau
2019-10-23 17:31 ` [PATCH v3 32/33] qdev: remove PROP_MEMORY_REGION Marc-André Lureau
2019-10-23 23:07 ` Philippe Mathieu-Daudé
2019-10-23 17:31 ` [PATCH v3 33/33] qdev: remove QDEV_PROP_PTR Marc-André Lureau
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