icside: bring back ->maskproc method

Bring back ->maskproc method since it is still needed for proper operation,
as noticed by Russell King:

> This change is bogus.
>
>         writeb(0, base + ICS_ARCIN_V6_INTROFFSET_1);
>         readb(base + ICS_ARCIN_V6_INTROFFSET_2);
>
>         writeb(0, base + ICS_ARCIN_V6_INTROFFSET_2);
>         readb(base + ICS_ARCIN_V6_INTROFFSET_1);
>
> This sequence of code does:
>
> 1. enable interrupt 1
> 2. disable interrupt 2
> 3. enable interrupt 2
> 4. disable interrupt 1
>
> which results in the interrupt for the second channel being enabled -
> leaving channel 1 blocked.
>
> Firstly, icside shares its two IDE channels with one DMA engine - so it's
> a simplex interface.  IDE supports those (or did when the code was written)
> serializing requests between the two interfaces.  libata does not.
>
> Secondly, the interrupt lines on icside float when there's no drive connected
> or when the drive has its NIEN bit set, which means that you get spurious
> screaming interrupts which can kill off all expansion card interrupts on
> the machine unless you disable the channel interrupt on the card.
>
> Since libata can not serialize the operation of the two channels like IDE
> can, the libata version of the icside driver does not contain the interrupt
> stearing logic.  Instead, it looks at the status after reset, and if
> nothing was found on that channel, it masks the interrupt from that
> channel.

This patch reverts changes done in commit dff8817 (I became confused due to
non-standard & undocumented ->maskproc method, anyway sorry about that).

Noticed-by: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 60 insertions, 4 deletions

diff --git a/drivers/ide/icside.c b/drivers/ide/icside.c
index 0f67f1abbbd3..d7e6f09aa86b 100644
--- a/drivers/ide/icside.c
+++ b/drivers/ide/icside.c
@@ -65,6 +65,8 @@ static struct cardinfo icside_cardinfo_v6_2 = {
 };
 
 struct icside_state {
+        unsigned int channel;
+        unsigned int enabled;
         void __iomem *irq_port;
         void __iomem *ioc_base;
         unsigned int sel;
@@ -114,11 +116,18 @@ static void icside_irqenable_arcin_v6 (struct expansion_card *ec, int irqnr)
         struct icside_state *state = ec->irq_data;
         void __iomem *base = state->irq_port;
 
-        writeb(0, base + ICS_ARCIN_V6_INTROFFSET_1);
-        readb(base + ICS_ARCIN_V6_INTROFFSET_2);
+        state->enabled = 1;
 
-        writeb(0, base + ICS_ARCIN_V6_INTROFFSET_2);
-        readb(base + ICS_ARCIN_V6_INTROFFSET_1);
+        switch (state->channel) {
+        case 0:
+                writeb(0, base + ICS_ARCIN_V6_INTROFFSET_1);
+                readb(base + ICS_ARCIN_V6_INTROFFSET_2);
+                break;
+        case 1:
+                writeb(0, base + ICS_ARCIN_V6_INTROFFSET_2);
+                readb(base + ICS_ARCIN_V6_INTROFFSET_1);
+                break;
+        }
 }
 
 /* Prototype: icside_irqdisable_arcin_v6 (struct expansion_card *ec, int irqnr)
@@ -128,6 +137,8 @@ static void icside_irqdisable_arcin_v6 (struct expansion_card *ec, int irqnr)
 {
         struct icside_state *state = ec->irq_data;
 
+        state->enabled = 0;
+
         readb(state->irq_port + ICS_ARCIN_V6_INTROFFSET_1);
         readb(state->irq_port + ICS_ARCIN_V6_INTROFFSET_2);
 }
@@ -149,6 +160,44 @@ static const expansioncard_ops_t icside_ops_arcin_v6 = {
         .irqpending     = icside_irqpending_arcin_v6,
 };
 
+/*
+ * Handle routing of interrupts.  This is called before
+ * we write the command to the drive.
+ */
+static void icside_maskproc(ide_drive_t *drive, int mask)
+{
+        ide_hwif_t *hwif = drive->hwif;
+        struct expansion_card *ec = ECARD_DEV(hwif->dev);
+        struct icside_state *state = ecard_get_drvdata(ec);
+        unsigned long flags;
+
+        local_irq_save(flags);
+
+        state->channel = hwif->channel;
+
+        if (state->enabled && !mask) {
+                switch (hwif->channel) {
+                case 0:
+                        writeb(0, state->irq_port + ICS_ARCIN_V6_INTROFFSET_1);
+                        readb(state->irq_port + ICS_ARCIN_V6_INTROFFSET_2);
+                        break;
+                case 1:
+                        writeb(0, state->irq_port + ICS_ARCIN_V6_INTROFFSET_2);
+                        readb(state->irq_port + ICS_ARCIN_V6_INTROFFSET_1);
+                        break;
+                }
+        } else {
+                readb(state->irq_port + ICS_ARCIN_V6_INTROFFSET_2);
+                readb(state->irq_port + ICS_ARCIN_V6_INTROFFSET_1);
+        }
+
+        local_irq_restore(flags);
+}
+
+static const struct ide_port_ops icside_v6_no_dma_port_ops = {
+        .maskproc               = icside_maskproc,
+};
+
 #ifdef CONFIG_BLK_DEV_IDEDMA_ICS
 /*
  * SG-DMA support.
@@ -228,6 +277,7 @@ static void icside_set_dma_mode(ide_drive_t *drive, const u8 xfer_mode)
 
 static const struct ide_port_ops icside_v6_port_ops = {
         .set_dma_mode           = icside_set_dma_mode,
+        .maskproc               = icside_maskproc,
 };
 
 static void icside_dma_host_set(ide_drive_t *drive, int on)
@@ -272,6 +322,11 @@ static int icside_dma_setup(ide_drive_t *drive, struct ide_cmd *cmd)
         BUG_ON(dma_channel_active(ec->dma));
 
         /*
+         * Ensure that we have the right interrupt routed.
+         */
+        icside_maskproc(drive, 0);
+
+        /*
          * Route the DMA signals to the correct interface.
          */
         writeb(state->sel | hwif->channel, state->ioc_base);
@@ -399,6 +454,7 @@ err_free:
 
 static const struct ide_port_info icside_v6_port_info __initdata = {
         .init_dma               = icside_dma_off_init,
+        .port_ops               = &icside_v6_no_dma_port_ops,
         .dma_ops                = &icside_v6_dma_ops,
         .host_flags             = IDE_HFLAG_SERIALIZE | IDE_HFLAG_MMIO,
         .mwdma_mask             = ATA_MWDMA2,