[PATCH 3/3] Add disk hotswap support to libata RESEND #2

[Lukasz Kosewski <lkosewsk@gmail.com>]

Patch 03:  Have sata_promise use the perfect, flawless API from the
previous patch

As described in the archives, this patch build on patch 02 in the
series to actually allow the sata_promise controller to hotswap.  Be
careful, untested!

This version comes with all of Jeff's suggestions (documented in the
patch itself).  It depends on patch 01 to apply, and both patch 01 and
02 to compile and run.

Luke Kosewski

01.08.05  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 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.
	* This is a resend of the original patch which in particular:
	  - Doesn't special-case the turning off of channel interrupts during a
	    hard reset to the SATAII150 controllers; all controllers now do
	    this.
	  - Actually aborts the interrupt handler if, after reading mmio_base +
	    PDC_INT_SEQMASK, we don't get ANYTHING (aka no device).
	  - On Jeff's suggestion, the whole hotswap system was changed over to
	    use a debounce timer; see patch 02 for that goodie.

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

--- linux/drivers/scsi/sata_promise.c.old	2005-07-28 20:43:52.000000000 -0700
+++ linux/drivers/scsi/sata_promise.c	2005-08-01 02:23:27.000000000 -0700
@@ -67,12 +67,16 @@ enum {
 	PDC_HAS_PATA		= (1 << 1), /* PDC20375/20575 has PATA */
 
 	PDC_RESET		= (1 << 11), /* HDMA reset */
+
+	HOTPLUG_PLUG		= 1,
+	HOTPLUG_UNPLUG		= 0,
 };
 
 
 struct pdc_port_priv {
 	u8			*pkt;
 	dma_addr_t		pkt_dma;
+	int			hotplug_status;
 };
 
 struct pdc_host_priv {
@@ -87,6 +91,7 @@ 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 int pdc_hotplug_action(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);
@@ -133,6 +138,7 @@ static struct ata_port_operations pdc_at
 	.port_start		= pdc_port_start,
 	.port_stop		= pdc_port_stop,
 	.host_stop		= ata_host_stop,
+	.hotplug_action		= pdc_hotplug_action,
 };
 
 static struct ata_port_info pdc_port_info[] = {
@@ -299,15 +305,61 @@ 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);
+
+	//Unmask channel hotplug interrupts
+	maskflags = readb(mmio + 2);
+	maskflags &= ~(0x11 << (u8)ap->hard_port_no);
+	writeb(maskflags, mmio + 2);
+}
+
 static void pdc_phy_reset(struct ata_port *ap)
 {
 	pdc_reset_port(ap);
-	if (ap->flags & ATA_FLAG_SATA)
-		sata_phy_reset(ap);
-	else
+	if (ap->flags & ATA_FLAG_SATA) {
+		/* A hard reset triggers a hotplug interrupt to be played out
+		 * on some controllers.  Hence, disable hotplug interrupts for
+		 * the reset, re-enable them when it's done.
+		 *
+		 * No PATA hotswap support yet
+		 */
+		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);
+	} else
 		pdc_pata_phy_reset(ap);
 }
 
+/* Should be called with host_set->lock held */
+static int pdc_hotplug_action(struct ata_port *ap)
+{
+	struct pdc_port_priv *pp = ap->private_data;
+	return pp->hotplug_status;
+}
+
 static void pdc_pata_cbl_detect(struct ata_port *ap)
 {
 	u8 tmp;
@@ -467,7 +519,9 @@ static irqreturn_t pdc_interrupt (int ir
 	struct ata_port *ap;
 	void *mmio_base;
 	u32 mask = 0;
-	unsigned int i, tmp, handled = 0;
+	u8 plugdata, maskflags;
+	struct pdc_host_priv *hp = host_set->private_data;
+	unsigned int i, tmp, handled = 0, hotplug_offset = hp->hotplug_offset;
 
 	VPRINTK("ENTER\n");
 
@@ -491,7 +545,7 @@ 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);
@@ -509,7 +563,40 @@ 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) {
+		struct pdc_port_priv *pp;
+		writeb(plugdata, mmio_base + hotplug_offset);
+		for (i = 0; i < host_set->n_ports; ++i) {
+			ap = host_set->ports[i];
+			pp = ap->private_data;
+			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 */
+				pp->hotplug_status = HOTPLUG_UNPLUG;
+				ata_hotplug_op(ap);
+				handled = 1;
+			} else if ((plugdata >> 4) & 0x1) {  //Check plug flag
+				/* Do stuff related to plugging in a device */
+				pp->hotplug_status = HOTPLUG_PLUG;
+				ata_hotplug_op(ap);
+				handled = 1;
+			}
+			plugdata >>= 1;
+		}
+	}
+
+	VPRINTK("EXIT 5\n");
        
 done_irq:
 	spin_unlock(&host_set->lock);
@@ -609,9 +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);