From 5359b938c088423a28c41499f183cd10824c1816 Mon Sep 17 00:00:00 2001 From: "Maciej W. Rozycki" Date: Thu, 12 Sep 2013 12:14:31 +0100 Subject: MIPS: DECstation I/O ASIC DMA interrupt handling fix This change complements commit d0da7c002f7b2a93582187a9e3f73891a01d8ee4 and brings clear_ioasic_irq back, renaming it to clear_ioasic_dma_irq at the same time, to make I/O ASIC DMA interrupts functional. Unlike ordinary I/O ASIC interrupts DMA interrupts need to be deasserted by software by writing 0 to the respective bit in I/O ASIC's System Interrupt Register (SIR), similarly to how CP0.Cause.IP0 and CP0.Cause.IP1 bits are handled in the CPU (the difference is SIR DMA interrupt bits are R/W0C so there's no need for an RMW cycle). Otherwise the handler is reentered over and over again. The only current user is the DEC LANCE Ethernet driver and its extremely uncommon DMA memory error handler that does not care when exactly the interrupt is cleared. Anticipating the use of DMA interrupts by the Zilog SCC driver this change however exports clear_ioasic_dma_irq for device drivers to choose the right application-specific sequence to clear the request explicitly rather than calling it implicitly in the .irq_eoi handler of `struct irq_chip'. Previously these interrupts were cleared in the .end handler of the said structure, before it was removed. Signed-off-by: Maciej W. Rozycki Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/5826/ Signed-off-by: Ralf Baechle --- arch/mips/dec/ioasic-irq.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'arch/mips/dec') diff --git a/arch/mips/dec/ioasic-irq.c b/arch/mips/dec/ioasic-irq.c index 824e08c7379..4b3e3a4375a 100644 --- a/arch/mips/dec/ioasic-irq.c +++ b/arch/mips/dec/ioasic-irq.c @@ -51,6 +51,14 @@ static struct irq_chip ioasic_irq_type = { .irq_unmask = unmask_ioasic_irq, }; +void clear_ioasic_dma_irq(unsigned int irq) +{ + u32 sir; + + sir = ~(1 << (irq - ioasic_irq_base)); + ioasic_write(IO_REG_SIR, sir); +} + static struct irq_chip ioasic_dma_irq_type = { .name = "IO-ASIC-DMA", .irq_ack = ack_ioasic_irq, -- cgit v1.2.3-70-g09d2