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Date: Wed, 14 Jan 2015 15:03:32 +0100
From: Boris Brezillon <boris.brezillon@...e-electrons.com>
To: Nicolas Ferre <nicolas.ferre@...el.com>
Cc: Thomas Gleixner <tglx@...utronix.de>,
Jason Cooper <jason@...edaemon.net>,
"Jean-Christophe Plagniol-Villard" <plagnioj@...osoft.com>,
Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>, "Rob Herring" <robh+dt@...nel.org>,
Pawel Moll <pawel.moll@....com>,
Mark Rutland <mark.rutland@....com>,
Ian Campbell <ijc+devicetree@...lion.org.uk>,
"Kumar Gala" <galak@...eaurora.org>, <devicetree@...r.kernel.org>
Subject: Re: [PATCH v2 1/5] irqchip: add dumb demultiplexer implementation
On Wed, 14 Jan 2015 14:36:42 +0100
Nicolas Ferre <nicolas.ferre@...el.com> wrote:
> Le 13/01/2015 19:46, Boris Brezillon a écrit :
> > Some interrupt controllers are multiplexing several peripheral IRQs on
> > a single interrupt line.
> > While this is not a problem for most IRQs (as long as all peripherals
> > request the interrupt with IRQF_SHARED flag set), multiplexing timers and
> > other type of peripherals will generate a WARNING (mixing IRQF_NO_SUSPEND
> > and !IRQF_NO_SUSPEND is prohibited).
> >
> > Create a dumb irq demultiplexer which simply forwards interrupts to all
> > peripherals (exactly what's happening with IRQ_SHARED) but keep a unique
> > irq number for each peripheral, thus preventing the IRQF_NO_SUSPEND
> > and !IRQF_NO_SUSPEND mix on a given interrupt.
> >
> > Signed-off-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
> > ---
> > drivers/irqchip/Kconfig | 4 ++
> > drivers/irqchip/Makefile | 1 +
> > drivers/irqchip/irq-dumb-demux.c | 70 ++++++++++++++++++++
> > include/linux/irq.h | 49 ++++++++++++++
> > include/linux/irqdomain.h | 1 +
> > kernel/irq/Kconfig | 5 ++
> > kernel/irq/Makefile | 1 +
> > kernel/irq/chip.c | 41 ++++++++++++
> > kernel/irq/dumb-demux-chip.c | 140 +++++++++++++++++++++++++++++++++++++++
> > kernel/irq/handle.c | 31 ++++++++-
> > kernel/irq/internals.h | 3 +
> > 11 files changed, 344 insertions(+), 2 deletions(-)
> > create mode 100644 drivers/irqchip/irq-dumb-demux.c
> > create mode 100644 kernel/irq/dumb-demux-chip.c
> >
> > diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
> > index cc79d2a..8a9df88 100644
> > --- a/drivers/irqchip/Kconfig
> > +++ b/drivers/irqchip/Kconfig
> > @@ -70,6 +70,10 @@ config BRCMSTB_L2_IRQ
> > select GENERIC_IRQ_CHIP
> > select IRQ_DOMAIN
> >
> > +config DUMB_DEMUX_IRQ
> > + bool
> > + select DUMB_IRQ_DEMUX_CHIP
> > +
> > config DW_APB_ICTL
> > bool
> > select GENERIC_IRQ_CHIP
> > diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> > index 9516a32..77f3c51 100644
> > --- a/drivers/irqchip/Makefile
> > +++ b/drivers/irqchip/Makefile
> > @@ -8,6 +8,7 @@ obj-$(CONFIG_ARCH_MVEBU) += irq-armada-370-xp.o
> > obj-$(CONFIG_ARCH_MXS) += irq-mxs.o
> > obj-$(CONFIG_ARCH_S3C24XX) += irq-s3c24xx.o
> > obj-$(CONFIG_DW_APB_ICTL) += irq-dw-apb-ictl.o
> > +obj-$(CONFIG_DUMB_DEMUX_IRQ) += irq-dumb-demux.o
> > obj-$(CONFIG_METAG) += irq-metag-ext.o
> > obj-$(CONFIG_METAG_PERFCOUNTER_IRQS) += irq-metag.o
> > obj-$(CONFIG_ARCH_MOXART) += irq-moxart.o
> > diff --git a/drivers/irqchip/irq-dumb-demux.c b/drivers/irqchip/irq-dumb-demux.c
> > new file mode 100644
> > index 0000000..dfa05ce
> > --- /dev/null
> > +++ b/drivers/irqchip/irq-dumb-demux.c
> > @@ -0,0 +1,70 @@
>
> Maybe add a little file header here. It's always better.
Sure, I just forgot it.
> > +#ifdef CONFIG_DUMB_IRQ_DEMUX_CHIP
> > +/**
> > + * handle_dumb_demux_irq - Dumb demuxer irq handle function.
> > + * @irq: the interrupt number
> > + * @desc: the interrupt description structure for this irq
> > + *
> > + * Dumb demux interrupts are sent from a demultiplexing interrupt handler
> > + * which is not able to decide which child interrupt interrupt handler
>
> typo: "interrupt interrupt"
I'll fix that.
>
> > + * should be called.
> > + *
> > + * Note: The caller is expected to handle the ack, clear, mask and
> > + * unmask issues if necessary.
> > + */
[...]
> > +
> > /*
> > * Called unconditionally from handle_level_irq() and only for oneshot
> > * interrupts from handle_fasteoi_irq()
> > diff --git a/kernel/irq/dumb-demux-chip.c b/kernel/irq/dumb-demux-chip.c
> > new file mode 100644
> > index 0000000..8e2de1d
> > --- /dev/null
> > +++ b/kernel/irq/dumb-demux-chip.c
> > @@ -0,0 +1,140 @@
> > +/*
> > + * Library implementing common dumb irq demux chip functions
> > + *
> > + * Copyright (C) 2015, Boris Brezillon
>
> License here, please.
Yep, I'll add it.
>
> > + */
> > +#include <linux/err.h>
> > +#include <linux/io.h>
> > +#include <linux/irq.h>
> > +#include <linux/slab.h>
> > +#include <linux/export.h>
> > +#include <linux/irq.h>
> > +#include <linux/irqdomain.h>
> > +#include <linux/irqchip/chained_irq.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/kernel_stat.h>
> > +#include <linux/syscore_ops.h>
> > +
> > +#include "internals.h"
> > +
> > +static void irq_dumb_demux_mask(struct irq_data *d)
> > +{
> > + struct irq_chip_dumb_demux *demux = irq_data_get_irq_chip_data(d);
> > +
> > + clear_bit(d->hwirq, &demux->unmasked);
> > +
> > + if (!demux->unmasked)
> > + disable_irq_nosync(demux->src_irq);
> > +}
> > +
> > +static void irq_dumb_demux_unmask(struct irq_data *d)
> > +{
> > + struct irq_chip_dumb_demux *demux = irq_data_get_irq_chip_data(d);
> > + bool enable_src_irq = !demux->unmasked;
>
> Why this additional "bool" unlike the other function above?
Because set_bit will modify the unmasked status and we must check if it
is equal to 0 (in other terms, all irqs are masked) before modifying it
in order to know whether we should enable the src irq or not.
>
> > +
> > + set_bit(d->hwirq, &demux->unmasked);
> > +
> > + if (enable_src_irq)
> > + enable_irq(demux->src_irq);
> > +}
> > +
[...]
> > +
> > +/**
> > + * irq_alloc_dumb_demux_chip - Allocate a dumb demux chip
> > + * @src_irq: irq feeding the dumb demux chip
> > + * @dd_flags: irq_dumb_demux_flags flags
> > + * @valid_irqs: Bitmask representing valid irqs
> > + * @clr_flags: irq_flags to clear when mapping an interrupt
> > + * @set_flags: irq_flags to set when mapping an interrupt
>
> Nit. not same order as the function parameters...
I'll fix that.
Thanks,
Boris
--
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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