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

[Lukasz Kosewski <lkosewsk@gmail.com>]

Hey Jeff, everyone.

This is a resend of patch 3 of my libata hotswap series, wherein I
found a silly flaw in my logic.  I don't know what kind of crack I was
smoking, but I somehow turned "a = a & ~b" in the Promise driver into
"a = a ^ b" in my hotswap code, which is clearly wrong.  I don't know
how it worked through my testing, but I'm willing to bet this is a
coincidence.  Please apply this patch instead of the previously sent
patch 03.

Luke Kosewski
Human Cannonball
Net Integration Technologies

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);