MIPS: DECstation I/O ASIC DMA interrupt classes

This change complements commits d0da7c002f7b2a93582187a9e3f73891a01d8ee4
[MIPS: DEC: Convert to new irq_chip functions] and
5359b938c088423a28c41499f183cd10824c1816 [MIPS: DECstation I/O ASIC DMA
interrupt handling fix] and implements automatic handling of the two
classes of DMA interrupts the I/O ASIC implements, informational and
errors.

Informational DMA interrupts do not stop the transfer and use the
`handle_edge_irq' handler that clears the request right away so that
another request may be recorded while the previous is being handled.

DMA error interrupts stop the transfer and require a corrective action
before DMA can be reenabled.  Therefore they use the `handle_fasteoi_irq'
handler that only clears the request on the way out.  Because MIPS
processor interrupt inputs, one of which the I/O ASIC's interrupt
controller is cascaded to, are level-triggered it is recommended that
error DMA interrupt action handlers are registered with the IRQF_ONESHOT
flag set so that they are run with the interrupt line masked.

This change removes the export of clear_ioasic_dma_irq that now does not
have to be called by device drivers to clear interrupts explicitly
anymore.  Originally these interrupts were cleared in the .end handler of
the `irq_chip' structure, before it was removed.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5874/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/dec/ioasic-irq.c b/arch/mips/dec/ioasic-irq.c
index 4b3e3a4..e04d973 100644 (file)
--- a/arch/mips/dec/ioasic-irq.c
+++ b/arch/mips/dec/ioasic-irq.c
@@ -1,7 +1,7 @@
 /*
  *     DEC I/O ASIC interrupts.
  *
- *     Copyright (c) 2002, 2003  Maciej W. Rozycki
+ *     Copyright (c) 2002, 2003, 2013  Maciej W. Rozycki
  *
  *     This program is free software; you can redistribute it and/or
  *     modify it under the terms of the GNU General Public License
@@ -51,22 +51,51 @@ static struct irq_chip ioasic_irq_type = {
        .irq_unmask = unmask_ioasic_irq,
 };
 
-void clear_ioasic_dma_irq(unsigned int irq)
+static void clear_ioasic_dma_irq(struct irq_data *d)
 {
        u32 sir;
 
-       sir = ~(1 << (irq - ioasic_irq_base));
+       sir = ~(1 << (d->irq - ioasic_irq_base));
        ioasic_write(IO_REG_SIR, sir);
+       fast_iob();
 }
 
 static struct irq_chip ioasic_dma_irq_type = {
        .name = "IO-ASIC-DMA",
-       .irq_ack = ack_ioasic_irq,
+       .irq_ack = clear_ioasic_dma_irq,
        .irq_mask = mask_ioasic_irq,
-       .irq_mask_ack = ack_ioasic_irq,
        .irq_unmask = unmask_ioasic_irq,
+       .irq_eoi = clear_ioasic_dma_irq,
 };
 
+/*
+ * I/O ASIC implements two kinds of DMA interrupts, informational and
+ * error interrupts.
+ *
+ * The formers do not stop DMA and should be cleared as soon as possible
+ * so that if they retrigger before the handler has completed, usually as
+ * a side effect of actions taken by the handler, then they are reissued.
+ * These use the `handle_edge_irq' handler that clears the request right
+ * away.
+ *
+ * The latters stop DMA and do not resume it until the interrupt has been
+ * cleared.  This cannot be done until after a corrective action has been
+ * taken and this also means they will not retrigger.  Therefore they use
+ * the `handle_fasteoi_irq' handler that only clears the request on the
+ * way out.  Because MIPS processor interrupt inputs, one of which the I/O
+ * ASIC is cascaded to, are level-triggered it is recommended that error
+ * DMA interrupt action handlers are registered with the IRQF_ONESHOT flag
+ * set so that they are run with the interrupt line masked.
+ *
+ * This mask has `1' bits in the positions of informational interrupts.
+ */
+#define IO_IRQ_DMA_INFO                                                        \
+       (IO_IRQ_MASK(IO_INR_SCC0A_RXDMA) |                              \
+        IO_IRQ_MASK(IO_INR_SCC1A_RXDMA) |                              \
+        IO_IRQ_MASK(IO_INR_ISDN_TXDMA) |                               \
+        IO_IRQ_MASK(IO_INR_ISDN_RXDMA) |                               \
+        IO_IRQ_MASK(IO_INR_ASC_DMA))
+
 void __init init_ioasic_irqs(int base)
 {
        int i;
@@ -79,7 +108,9 @@ void __init init_ioasic_irqs(int base)
                irq_set_chip_and_handler(i, &ioasic_irq_type,
                                         handle_level_irq);
        for (; i < base + IO_IRQ_LINES; i++)
-               irq_set_chip(i, &ioasic_dma_irq_type);
+               irq_set_chip_and_handler(i, &ioasic_dma_irq_type,
+                                        1 << (i - base) & IO_IRQ_DMA_INFO ?
+                                        handle_edge_irq : handle_fasteoi_irq);
 
        ioasic_irq_base = base;
 }

diff --git a/arch/mips/include/asm/dec/ioasic.h b/arch/mips/include/asm/dec/ioasic.h
index a6e505a..be4d62a 100644 (file)
--- a/arch/mips/include/asm/dec/ioasic.h
+++ b/arch/mips/include/asm/dec/ioasic.h
@@ -31,8 +31,6 @@ static inline u32 ioasic_read(unsigned int reg)
        return ioasic_base[reg / 4];
 }
 
-extern void clear_ioasic_dma_irq(unsigned int irq);
-
 extern void init_ioasic_irqs(int base);
 
 extern int dec_ioasic_clocksource_init(void);

diff --git a/drivers/net/ethernet/amd/declance.c b/drivers/net/ethernet/amd/declance.c
index 94edc9c..1b89f1a 100644 (file)
--- a/drivers/net/ethernet/amd/declance.c
+++ b/drivers/net/ethernet/amd/declance.c
@@ -725,7 +725,6 @@ static irqreturn_t lance_dma_merr_int(int irq, void *dev_id)
 {
        struct net_device *dev = dev_id;
 
-       clear_ioasic_dma_irq(irq);
        printk(KERN_ERR "%s: DMA error\n", dev->name);
        return IRQ_HANDLED;
 }
@@ -812,7 +811,7 @@ static int lance_open(struct net_device *dev)
        if (lp->dma_irq >= 0) {
                unsigned long flags;
 
-               if (request_irq(lp->dma_irq, lance_dma_merr_int, 0,
+               if (request_irq(lp->dma_irq, lance_dma_merr_int, IRQF_ONESHOT,
                                "lance error", dev)) {
                        free_irq(dev->irq, dev);
                        printk("%s: Can't get DMA IRQ %d\n", dev->name,