Le 14/01/2015 15:03, Boris Brezillon a ?crit :

On Wed, 14 Jan 2015 14:36:42 +0100
Nicolas Ferre [off-list ref] wrote:

quoted

Le 13/01/2015 19:46, Boris Brezillon a ?crit :

quoted

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 <redacted>
---
 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

[..]

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+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.

pfffff! ok, sorry for the noise then ;-)

quoted

quoted

+
+	set_bit(d->hwirq, &demux->unmasked);
+
+	if (enable_src_irq)
+		enable_irq(demux->src_irq);
+}
+

[...]

Bye,
-- 
Nicolas Ferre