[PATCH 2.6.14-rc1 3/3] Add disk hotswap support to libata RESEND #3

[Lukasz Kosewski <lkosewsk@gmail.com>]

Patch 3/3 for libata hotswapping.  The sata_promise driver caught red
handed using the new hotswapping API.  Depends on patches 1 and 2. 
More comments in patch header.

Luke Kosewski

15.09.05    Luke Kosewski   <lkosewsk@nit.ca>

	* A patch to sata_promise.c (dependent on patches 1 and 2 in this
	  series) which makes it use the hotswap API in patch 2.  The Promise
	  controllers are fairly simple in terms of their hotplug mechanism,
	  so none of the funky 'janitor' functions are used here.
	  ata_hotplug_plug is called on a plug event, and ata_hotplug_unplug on
	  an unplug.  Simple, simple.
	* Pending some confirmation and suggestions from Jim Ramsay
	  (jim.ramsay@gmail.com) the interrupt handler might change to check for
	  DMA commands completing as WELL as hotplug events in the same pass.

diff -rpuN linux-2.6.14-rc1/drivers/scsi/sata_promise.c linux-2.6.14-rc1-new/drivers/scsi/sata_promise.c
--- linux-2.6.14-rc1/drivers/scsi/sata_promise.c	2005-09-14 19:57:54.000000000 -0400
+++ linux-2.6.14-rc1-new/drivers/scsi/sata_promise.c	2005-09-14 20:16:09.000000000 -0400
@@ -332,10 +332,43 @@ static void pdc_reset_port(struct ata_po
 	readl(mmio);	/* flush */
 }
 
+/* Mask hotplug interrupts for one channel (ap) */
+static inline void pdc_disable_channel_hotplug_interrupts(struct ata_port *ap)
+{
+	struct pdc_host_priv *hp = ap->host_set->private_data;
+	void *mmio = ap->host_set->mmio_base + hp->hotplug_offset + 2;
+
+	u8 maskflags = readb(mmio);
+	maskflags |= (0x11 << (u8)ap->hard_port_no);
+	writeb(maskflags, mmio);
+}
+
+/* Clear and unmask hotplug interrupts for one channel (ap) */
+static inline void pdc_enable_channel_hotplug_interrupts(struct ata_port *ap)
+{
+	struct pdc_host_priv *hp = ap->host_set->private_data;
+	void *mmio = ap->host_set->mmio_base + hp->hotplug_offset;
+
+	//Clear channel hotplug interrupts
+	u8 maskflags = readb(mmio);
+	maskflags |= (0x11 << (u8)ap->hard_port_no);
+	writeb(maskflags, mmio);
+
+/* Clear and unmask hotplug interrupts for one channel (ap) */
+static inline void pdc_enable_channel_hotplug_interrupts(struct ata_port *ap)
+{
+	struct pdc_host_priv *hp = ap->host_set->private_data;
+	void *mmio = ap->host_set->mmio_base + hp->hotplug_offset;
+
+	//Clear channel hotplug interrupts
+	u8 maskflags = readb(mmio);
+	maskflags |= (0x11 << (u8)ap->hard_port_no);
+	writeb(maskflags, mmio);
+
+	//Unmask channel hotplug interrupts
+	maskflags = readb(mmio + 2);
+	maskflags &= ~(0x11 << (u8)ap->hard_port_no);
+	writeb(maskflags, mmio + 2);
+}
+
 static void pdc_sata_phy_reset(struct ata_port *ap)
 {
 	pdc_reset_port(ap);
-	sata_phy_reset(ap);
+	if (ap->flags & ATA_FLAG_SATA_RESET) {
+		pdc_disable_channel_hotplug_interrupts(ap);
+		sata_phy_reset(ap);
+		pdc_enable_channel_hotplug_interrupts(ap);
+	} else
+		sata_phy_reset(ap);
 }
 
 static void pdc_pata_phy_reset(struct ata_port *ap)
@@ -485,11 +518,13 @@ static void pdc_irq_clear(struct ata_por
 static irqreturn_t pdc_interrupt (int irq, void *dev_instance, struct pt_regs *regs)
 {15.09.05    Luke Kosewski   <lkosewsk@nit.ca>

	* A patch to add a general-purpose hotswap framework to libata.  This is
	  resend #3 wherein we have a new API!  Driver writers call
	  ata_hotplug_plug or ata_hotplug_unplug when a plug/unplug event
	  occurs - it takes care of the rest.  The idea is to make the sequence
	  of events as straightforward as possible and not clutter the code
	  with exceptions; as a result, a series of 'hooks' can be provided at
	  points in the code for drivers that need it (such as the Silicon
	  Image drivers which need a reset performed on device removal).  See
	  'hotplug_(un)plug_janitor' for more info.
	* This edition is very streamlined.  I like it.  An area for improvement
	  might facilitate the removal of the ata_scsi_prepare_qc_abort function
	  in favour of changes to ata_qc_complete, but that can be up to debate.
 	struct ata_host_set *host_set = dev_instance;
+	struct pdc_host_priv *hp = host_set->private_data;
 	struct ata_port *ap;
 	u32 mask = 0;
 	unsigned int i, tmp;
-	unsigned int handled = 0;
+	unsigned int handled = 0, hotplug_offset = hp->hotplug_offset;
 	void __iomem *mmio_base;
+	u8 plugdata, maskflags;
 
 	VPRINTK("ENTER\n");
 
@@ -513,7 +548,7 @@ static irqreturn_t pdc_interrupt (int ir
 	mask &= 0xffff;		/* only 16 tags possible */
 	if (!mask) {
 		VPRINTK("QUICK EXIT 3\n");
-		goto done_irq;
+		goto try_hotplug;
 	}
 
 	writel(mask, mmio_base + PDC_INT_SEQMASK);
@@ -532,7 +567,36 @@ static irqreturn_t pdc_interrupt (int ir
 		}
 	}
 
-	VPRINTK("EXIT\n");
+	if (handled) {
+		VPRINTK("EXIT 4\n");
+		goto done_irq;
+	}
+
+try_hotplug:
+	plugdata = readb(mmio_base + hotplug_offset);
+	maskflags = readb(mmio_base + hotplug_offset + 2);
+	plugdata &= ~maskflags;
+	if (plugdata) {
+		writeb(plugdata, mmio_base + hotplug_offset);
+		for (i = 0; i < host_set->n_ports; ++i) {
+			ap = host_set->ports[i];
+			if (!(ap->flags & ATA_FLAG_SATA))
+				continue;  //No PATA support here... yet
+			// Check unplug flag
+			if (plugdata & 0x1) {
+				/* Do stuff related to unplugging a device */
+				ata_hotplug_unplug(ap);
+				handled = 1;
+			} else if ((plugdata >> 4) & 0x1) {  //Check plug flag
+				/* Do stuff related to plugging in a device */
+				ata_hotplug_plug(ap);
+				handled = 1;
+			}
+			plugdata >>= 1;
+		}
+	}
+
+	VPRINTK("EXIT 5\n");
 
 done_irq:
 	spin_unlock(&host_set->lock);
@@ -632,9 +696,9 @@ static void pdc_host_init(unsigned int c
 	tmp = readl(mmio + hotplug_offset);
 	writel(tmp | 0xff, mmio + hotplug_offset);
 
-	/* mask plug/unplug ints */
+	/* unmask plug/unplug ints */
 	tmp = readl(mmio + hotplug_offset);
-	writel(tmp | 0xff0000, mmio + hotplug_offset);
+	writel(tmp & ~0xff0000, mmio + hotplug_offset);
 
 	/* reduce TBG clock to 133 Mhz. */
 	tmp = readl(mmio + PDC_TBG_MODE);