[PATCH 3/3] Add disk hotswap support to libata

[Lukasz Kosewski <lkosewsk@nit.ca>]

This patch is an implementation of hotswap on the sata_promise module, 
tested on SATA150 and SATAII150 Promise controllers.  It depends on 
patch 01 from this series of patches to apply, and both 01 and 02 in 
order to compile.

We handle hotplug interrupts and call our new API functions in libata.

There is also one new part for the SATAII150 controllers and how they
handle a phy_reset, since they seem to want to re-spew their last 
hotplug interrupt unless we mask and clear it.

I don't expect this to be too contentious either.

Luke Kosewski
Human Cannonball
Net Integration Technologies

Signed-off-by:  Luke Kosewski <lkosewsk@nit.ca>

21.07.05  Luke Kosewski  <lkosewsk@nit.ca>

	* A full implementation of hotplug on a libata controller, this being
	  the Promise Tx4/Tx2 Plus controller line (both SATA150 and SATAII150).
	  Almost all of the code pertaining to how to talk to the hotplug
	  registers has been stolen from the pdc-ulsata2 and ultra-1.0.8 Promise
	  drivers.  This involves detecting when we have an interrupt pending
	  and on what device, as well as the bit where a hard SATA reset gets
	  a SATAII150 controller to re-spew a plug interrupt.
	* Note that the hotplug handling code comes AFTER the normal interrupt
	  handling code in pdc_interrupt_common; this is because we're much
	  more likely to receive normal interrupts, so this drops the AVERAGE
	  interrupt handling time down a lot.

Signed-off-by:  Luke Kosewski <lkosewsk@nit.ca>

--- linux-2.6.13-rc3/drivers/scsi/sata_promise.c.old	2005-07-21 13:52:13.037895639 -0400
+++ linux-2.6.13-rc3/drivers/scsi/sata_promise.c	2005-07-21 13:55:53.490964645 -0400
@@ -84,6 +84,7 @@ static void pdc_eng_timeout(struct ata_p
 static int pdc_port_start(struct ata_port *ap);
 static void pdc_port_stop(struct ata_port *ap);
 static void pdc_phy_reset(struct ata_port *ap);
+static void pdc2_phy_reset(struct ata_port *ap);
 static void pdc_pata_phy_reset(struct ata_port *ap);
 static void pdc_pata_cbl_detect(struct ata_port *ap);
 static void pdc_qc_prep(struct ata_queued_cmd *qc);
@@ -139,7 +140,7 @@ static struct ata_port_operations pdc2_a
 	.check_status		= ata_check_status,
 	.exec_command		= pdc_exec_command_mmio,
 	.dev_select		= ata_std_dev_select,
-	.phy_reset		= pdc_phy_reset,
+	.phy_reset		= pdc2_phy_reset,
 	.qc_prep		= pdc_qc_prep,
 	.qc_issue		= pdc_qc_issue_prot,
 	.eng_timeout		= pdc_eng_timeout,
@@ -325,6 +326,48 @@ static void pdc_phy_reset(struct ata_por
 		pdc_pata_phy_reset(ap);
 }
 
+/* Mask hotplug interrupts for one channel (ap) */
+static inline void pdc2_disable_channel_hotplug_interrupts(struct ata_port *ap)
+{
+	void *mmio = ap->host_set->mmio_base + PDC2_SATA_PLUG_CSR + 2;
+
+	u8 maskflags = readb(mmio);
+	maskflags |= (0x11 << (u8)ap->hard_port_no);
+	writeb(maskflags, mmio);
+}
+
+static inline void pdc2_enable_channel_hotplug_interrupts(struct ata_port *ap)
+{
+
+	void *mmio = ap->host_set->mmio_base + PDC2_SATA_PLUG_CSR;
+
+	//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 pdc2_phy_reset(struct ata_port *ap)
+{
+	/* As observed on the Promise SATAII150 Tx2 Plus/Tx4, giving the
+	 * controller a hard reset triggers another hotplug interrupt.  So
+	 * disable them for the hard reset, and re-enable afterwards.
+	 *
+	 * No PATA support here yet
+	 */
+	if (ap->flags & ATA_FLAG_SATA_RESET && ap->flags & ATA_FLAG_SATA) {
+		pdc2_disable_channel_hotplug_interrupts(ap);
+		pdc_phy_reset(ap);
+		pdc2_enable_channel_hotplug_interrupts(ap);
+	} else
+		pdc_phy_reset(ap);
+}
+
 static void pdc_pata_cbl_detect(struct ata_port *ap)
 {
 	u8 tmp;
@@ -483,6 +526,7 @@ static inline unsigned int pdc_interrupt
 	struct ata_host_set *host_set = dev_instance;
 	struct ata_port *ap;
 	void *mmio_base;
+	u8 plugdata, maskflags;
 	u32 mask = 0;
 	unsigned int i, tmp, handled = 0;
 	unsigned long flags;
@@ -492,21 +536,18 @@ static inline unsigned int pdc_interrupt
 	}
 
 	mmio_base = host_set->mmio_base;
-	
+
 	spin_lock_irqsave(&host_set->lock, flags);
 
 	/* reading should also clear interrupts */
 	mask = readl(mmio_base + PDC_INT_SEQMASK);
 
-	if (mask == 0xffffffff) {
-		VPRINTK("QUICK EXIT 2\n");
-		goto done_irq;
-	}
+	if (mask == 0xffffffff)
+		goto try_hotplug;
+
 	mask &= 0xffff;		/* only 16 tags possible */
-	if (!mask) {
-		VPRINTK("QUICK EXIT 3\n");
-		goto done_irq;
-	}
+	if (!mask)
+		goto try_hotplug;
 
 	writel(mask, mmio_base + PDC_INT_SEQMASK);
 
@@ -522,7 +563,32 @@ static inline unsigned int pdc_interrupt
 				handled += pdc_host_intr(ap, qc);
 		}
 	}
-       
+
+	if (handled)
+		goto done_irq;
+
+try_hotplug:
+	plugdata = readb(mmio_base + hotplug_regs);
+	maskflags = readb(mmio_base + hotplug_regs + 2);
+	plugdata &= ~maskflags;
+	if (plugdata) {
+		writeb(plugdata, mmio_base + hotplug_regs);
+		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 & 0x01) {
+				ata_hotplug_unplug(ap);
+				handled = 1;
+			} else if ((plugdata >> 4) & 0x01) {  //Check plug flag
+				ata_hotplug_plug(ap);
+				handled = 1;
+			}
+			plugdata >>= 1;
+		}
+	}
+
 done_irq:
 	spin_unlock_irqrestore(&host_set->lock, flags);
 	return handled;
@@ -636,9 +702,9 @@ static void pdc_host_init(unsigned int c
 	tmp = readl(offset);
 	writel(tmp | 0xff, offset);
 
-	/* mask plug/unplug ints */
+	/* unmask plug/unplug ints */
 	tmp = readl(offset);
-	writel(tmp | 0xff0000, offset);
+	writel(tmp & 0xff00ffff, offset);
 
 	/* reduce TBG clock to 133 Mhz. */
 	tmp = readl(mmio + PDC_TBG_MODE);