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Date: Tue, 15 Apr 2014 12:30:27 -0700
From: David Cohen <david.a.cohen@...ux.intel.com>
To: Guenter Roeck <linux@...ck-us.net>
Cc: wim@...ana.be, tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
x86@...nel.org, linux-kernel@...r.kernel.org,
linux-watchdog@...r.kernel.org, gnomes@...rguk.ukuu.org.uk
Subject: Re: [PATCH v3 2/2] x86: intel-mid: add watchdog platform code for
Merrifield
On Tue, Apr 15, 2014 at 12:09:02PM -0700, Guenter Roeck wrote:
> On Tue, Apr 15, 2014 at 11:41:12AM -0700, David Cohen wrote:
> > This patch adds platform code for Intel Merrifield.
> > Since the watchdog is not part of SFI table, we have no other option but
> > to manually register watchdog's platform device (argh!).
> >
> argh ... does this really belong into the commit log ?
Yes. It means: "this developer was forced to do this ugly thing due to
fw-related sloppiness".
>
> > Signed-off-by: David Cohen <david.a.cohen@...ux.intel.com>
> > ---
> > arch/x86/platform/intel-mid/device_libs/Makefile | 1 +
> > .../platform/intel-mid/device_libs/platform_wdt.c | 63 ++++++++++++++++++++++
> > 2 files changed, 64 insertions(+)
> > create mode 100644 arch/x86/platform/intel-mid/device_libs/platform_wdt.c
> >
> > diff --git a/arch/x86/platform/intel-mid/device_libs/Makefile b/arch/x86/platform/intel-mid/device_libs/Makefile
> > index 097e7a7940d8..af9307f2cc28 100644
> > --- a/arch/x86/platform/intel-mid/device_libs/Makefile
> > +++ b/arch/x86/platform/intel-mid/device_libs/Makefile
> > @@ -20,3 +20,4 @@ obj-$(subst m,y,$(CONFIG_DRM_MEDFIELD)) += platform_tc35876x.o
> > obj-$(subst m,y,$(CONFIG_SERIAL_MRST_MAX3110)) += platform_max3111.o
> > # MISC Devices
> > obj-$(subst m,y,$(CONFIG_KEYBOARD_GPIO)) += platform_gpio_keys.o
> > +obj-$(subst m,y,$(CONFIG_INTEL_MID_WATCHDOG)) += platform_wdt.o
> > diff --git a/arch/x86/platform/intel-mid/device_libs/platform_wdt.c b/arch/x86/platform/intel-mid/device_libs/platform_wdt.c
> > new file mode 100644
> > index 000000000000..653242110d57
> > --- /dev/null
> > +++ b/arch/x86/platform/intel-mid/device_libs/platform_wdt.c
> > @@ -0,0 +1,63 @@
> > +/*
> > + * platform_wdt.c: Watchdog platform library file
> > + *
> > + * (C) Copyright 2014 Intel Corporation
> > + * Author: David Cohen <david.a.cohen@...ux.intel.com>
> > + *
> > + * This program is free software; you can redistribute it and/or
> > + * modify it under the terms of the GNU General Public License
> > + * as published by the Free Software Foundation; version 2
> > + * of the License.
> > + */
> > +
> > +#include <linux/init.h>
> > +#include <linux/intel-mid_wdt.h>
>
> /platform_data/...
Ack
>
> > +#include <linux/interrupt.h>
> > +#include <linux/platform_device.h>
> > +#include <asm/intel-mid.h>
> > +
> > +#define TANGIER_EXT_TIMER0_MSI 15
> > +
> > +static struct platform_device wdt_dev = {
> > + .name = "intel_mid_wdt",
> > + .id = -1,
> > +};
> > +
> > +static int tangier_probe(void)
> > +{
> > + int ioapic;
> > + struct io_apic_irq_attr irq_attr;
> > +
> = { };
> would ensure that there are no un-initialized variables
> if the structure definition ever changes.
>
> Or just pre-initialize the entire structure as much as possible.
The first suggestion seems better.
>
> > + ioapic = mp_find_ioapic(TANGIER_EXT_TIMER0_MSI);
> > + if (ioapic >= 0) {
> > + irq_attr.ioapic = ioapic;
> > + irq_attr.ioapic_pin = TANGIER_EXT_TIMER0_MSI;
> > + irq_attr.trigger = 1;
> > + irq_attr.polarity = 0; /* Active high */
> > + io_apic_set_pci_routing(NULL, TANGIER_EXT_TIMER0_MSI,
> > + &irq_attr);
>
> No need for an error check ? I understand no one else does,
> but why does the function return an error if no one cares about it ?
That's an interesting question. But whatever is the answer, I believe
checking the error makes more sense. I'll change it.
>
> > + } else {
> > + pr_warn("intel_mid_wdt: can not find interrupt %d in ioapic\n",
> > + TANGIER_EXT_TIMER0_MSI);
>
> As mentioned earlier, I think it would pake sense to pass
> struct platform_device * as argument and use dev_warn.
>
> It would also enable you to use the irq passed from the parameter
> instead of checking for the hard-coded define.
Ack.
>
> > + return -EINVAL;
>
> Why not return the error returned by mp_find_ioapic() ?
My intention was to ensure in this scenario we got the wrong IRQ. But it
perhaps makes more sense to keep the original error.
Thanks again for the review.
Br, David
>
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static struct intel_mid_wdt_pdata tangier_pdata = {
> > + .irq = TANGIER_EXT_TIMER0_MSI,
> > + .probe = tangier_probe,
> > +};
> > +
> > +static int __init register_mid_wdt(void)
> > +{
> > + if (intel_mid_identify_cpu() == INTEL_MID_CPU_CHIP_TANGIER) {
> > + wdt_dev.dev.platform_data = &tangier_pdata;
> > + return platform_device_register(&wdt_dev);
> > + }
> > +
> > + return -ENODEV;
> > +}
> > +
> > +rootfs_initcall(register_mid_wdt);
> > --
> > 1.9.1
> >
> > --
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> >
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