Re: [PATCH 7/8] ax88796: Add X-Surf 100 zorro driver providing an ax88796 platform device
Hi Michael,
On Tue, Nov 17, 2015 at 6:59 PM, Michael Karcher
<kernel@mkarcher.dialup.fu-berlin.de> wrote:
> On 17.11.2015 09:16, Geert Uytterhoeven wrote:
>>> +static int xsurf100_probe(struct zorro_dev *zdev, const struct zorro_device_id *ent)
>>> +{
>>> + struct platform_device *pdev;
>>> + struct ax_plat_data ax88796_data;
>>> + struct resource res[2] = {
>>> + DEFINE_RES_IRQ(IRQ_AMIGA_PORTS),
>>> + DEFINE_RES_IO(zdev->resource.start + XS1000_8390_BASE, 4 * 0x20)
>>> + };
>>> + int reg;
>>> + u32 reg_offsets[32];
>>> +
>>> + for (reg = 0; reg < 0x20; reg++)
>>> + reg_offsets[reg] = 4;
>>> +
>>> + ax88796_data.flags = AXFLG_HAS_EEPROM;
>>> + ax88796_data.wordlength = 2;
>>> + ax88796_data.dcr_val = 0x48;
>>> + ax88796_data.rcr_val = 0x40;
>>> + ax88796_data.reg_offsets = reg_offsets;
>>> +
>>> + // TODO: xsurf100 specific accelerated data exchange
>>> +
>>> + pdev = platform_device_register_resndata(
>>> + &zdev->dev, "ax88796", zdev->slotaddr,
>>> + res, 2,
>>> + &ax88796_data, sizeof ax88796_data);
>>> +
>>> + // TODO: NULL check
>>> + zorro_set_drvdata(zdev, pdev);
>> This looks a bit strange to me: storing another platform device in the
>> driver-specific data. But I guess it's valid ;-)
> We get a zorro device from the amiga subsystem for each XSurf 100 board
> installed in the machine. I want to bind the platform driver ax88796 to
> a subrange of the address space of the XSurf 100. To get the platform
> driver bound, I think I need to create a platform device (for each XSurf
> 100 Zorro device, so I can't have a static platform device allocated in
> the Zorro driver). If I dynamically create a platform device, I have to
> save the pointer somewhere, so I can remove the platform device when the
> module gets unloaded. For me, the obvious place to store the pointer is
> the driver-specific data of the Zorro device.
> If you have a different suggestion on how to connect the ax88796
> platform driver to a Zorro device that looks less strange to you, I am
> happy to learn a different way.
Sure, I understand why you're doing it.
>> BTW, as most Zorro boards are made of one or more "discrete" devices
>> (e.g. an IDE and Ethernet combo), but only one zorro_driver can bind to it,
>> I started converting Zorro drivers to MFD drivers a few years ago.
> The mfd framework might in fact be the different way I should learn
> about. It feels a bit like the approach I used in xsurf100.c is
> reinventing the mfd stuff, but I still have to find good documentation
> on how to use the mfd framework. I didn't find anything in
> linux/Documentation, and the comments in linux/include/linux/mfd/core.h
> have a quite steep learning curve.
Yeah, it looks quite complex ;-)
But in the end it's just about calling mfd_add_devices(), which will
create the needed platform_device(s) for you from a list of mfd "cells".
>> Unfortunately I still haven't finished that.
>> It would also make it simpler to embed a normal ax88796 platform device.
> I don't see yet how your conversion of present Zorro drivers would help
> for this new xsurf100 driver. On the other hand, if you just meant to
> point out using a mfd driver instead of the "create platform devices by
> hand" approach, *like* you are using for other drivers, I got your point
> and you are likely right.
Yes, that's what the MFD subsystem is about.
I've pushed my work-in-progress to
https://git.kernel.org/cgit/linux/kernel/git/geert/linux-m68k.git/log/?h=zorro-mfd
Please have a look at the various drivers/zorro/*-mfd.c files for inspiration.
drivers/zorro/8390-cell.c is a dummy cell driver, which is basically a
platform device driver. For X-Surf 100 that would be the existing ax88796
driver.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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