floppy: request and release only the ports we actually use

The floppy driver requests an I/O port it doesn't need, and sometimes this
causes a conflict with a motherboard device reported by PNPBIOS.

This patch makes the floppy driver request and release only the ports it
actually uses.  It also factors out the request/release stuff and the
io-ports list so they're all in one place now.

The current floppy driver uses only these ports:

    0x3f2 (FD_DOR)
    0x3f4 (FD_STATUS)
    0x3f5 (FD_DATA)
    0x3f7 (FD_DCR/FD_DIR)

but it requests 0x3f2-0x3f5 and 0x3f7, which includes the unused port
0x3f3.

Some BIOSes report 0x3f3 as a motherboard resource.  The PNP system driver
reserves that, which causes a conflict when the floppy driver requests
0x3f2-0x3f5 later.

Philippe reported that this conflict broke the floppy driver between
2.6.11 and 2.6.22.  His PNPBIOS reports these devices:

    $ cat 00:07/id 00:07/resources	# motherboard device
    PNP0c02
    state = active
    io 0x80-0x80
    io 0x10-0x1f
    io 0x22-0x3f
    io 0x44-0x5f
    io 0x90-0x9f
    io 0xa2-0xbf
    io 0x3f0-0x3f1
    io 0x3f3-0x3f3

    $ cat 00:03/id 00:03/resources	# floppy device
    PNP0700
    state = active
    io 0x3f4-0x3f5
    io 0x3f2-0x3f2

Reference:
    http://lkml.org/lkml/2009/1/31/162

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Reported-by: Philippe De Muyter <phdm@macqel.be>
Tested-by: Philippe De Muyter <phdm@macqel.be>
Cc: Adam M Belay <abelay@mit.edu>
Cc: Robert Hancock <hancockrwd@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/block/floppy.c

@@ -558,6 +558,8 @@ static void process_fd_request(void);
 static void recalibrate_floppy(void);
 static void floppy_shutdown(unsigned long);
 
+static int floppy_request_regions(int);
+static void floppy_release_regions(int);
 static int floppy_grab_irq_and_dma(void);
 static void floppy_release_irq_and_dma(void);
 
@@ -4274,8 +4276,7 @@ static int __init floppy_init(void)
 		FDCS->rawcmd = 2;
 		if (user_reset_fdc(-1, FD_RESET_ALWAYS, 0)) {
 			/* free ioports reserved by floppy_grab_irq_and_dma() */
-			release_region(FDCS->address + 2, 4);
-			release_region(FDCS->address + 7, 1);
+			floppy_release_regions(fdc);
 			FDCS->address = -1;
 			FDCS->version = FDC_NONE;
 			continue;
@@ -4284,8 +4285,7 @@ static int __init floppy_init(void)
 		FDCS->version = get_fdc_version();
 		if (FDCS->version == FDC_NONE) {
 			/* free ioports reserved by floppy_grab_irq_and_dma() */
-			release_region(FDCS->address + 2, 4);
-			release_region(FDCS->address + 7, 1);
+			floppy_release_regions(fdc);
 			FDCS->address = -1;
 			continue;
 		}
@@ -4358,6 +4358,47 @@ out_put_disk:
 
 static DEFINE_SPINLOCK(floppy_usage_lock);
 
+static const struct io_region {
+	int offset;
+	int size;
+} io_regions[] = {
+	{ 2, 1 },
+	/* address + 3 is sometimes reserved by pnp bios for motherboard */
+	{ 4, 2 },
+	/* address + 6 is reserved, and may be taken by IDE.
+	 * Unfortunately, Adaptec doesn't know this :-(, */
+	{ 7, 1 },
+};
+
+static void floppy_release_allocated_regions(int fdc, const struct io_region *p)
+{
+	while (p != io_regions) {
+		p--;
+		release_region(FDCS->address + p->offset, p->size);
+	}
+}
+
+#define ARRAY_END(X) (&((X)[ARRAY_SIZE(X)]))
+
+static int floppy_request_regions(int fdc)
+{
+	const struct io_region *p;
+
+	for (p = io_regions; p < ARRAY_END(io_regions); p++) {
+		if (!request_region(FDCS->address + p->offset, p->size, "floppy")) {
+			DPRINT("Floppy io-port 0x%04lx in use\n", FDCS->address + p->offset);
+			floppy_release_allocated_regions(fdc, p);
+			return -EBUSY;
+		}
+	}
+	return 0;
+}
+
+static void floppy_release_regions(int fdc)
+{
+	floppy_release_allocated_regions(fdc, ARRAY_END(io_regions));
+}
+
 static int floppy_grab_irq_and_dma(void)
 {
 	unsigned long flags;
@@ -4399,18 +4440,8 @@ static int floppy_grab_irq_and_dma(void)
 
 	for (fdc = 0; fdc < N_FDC; fdc++) {
 		if (FDCS->address != -1) {
-			if (!request_region(FDCS->address + 2, 4, "floppy")) {
-				DPRINT("Floppy io-port 0x%04lx in use\n",
-				       FDCS->address + 2);
-				goto cleanup1;
-			}
-			if (!request_region(FDCS->address + 7, 1, "floppy DIR")) {
-				DPRINT("Floppy io-port 0x%04lx in use\n",
-				       FDCS->address + 7);
-				goto cleanup2;
-			}
-			/* address + 6 is reserved, and may be taken by IDE.
-			 * Unfortunately, Adaptec doesn't know this :-(, */
+			if (floppy_request_regions(fdc))
+				goto cleanup;
 		}
 	}
 	for (fdc = 0; fdc < N_FDC; fdc++) {
@@ -4432,15 +4463,11 @@ static int floppy_grab_irq_and_dma(void)
 	fdc = 0;
 	irqdma_allocated = 1;
 	return 0;
-cleanup2:
-	release_region(FDCS->address + 2, 4);
-cleanup1:
+cleanup:
 	fd_free_irq();
 	fd_free_dma();
-	while (--fdc >= 0) {
-		release_region(FDCS->address + 2, 4);
-		release_region(FDCS->address + 7, 1);
-	}
+	while (--fdc >= 0)
+		floppy_release_regions(fdc);
 	spin_lock_irqsave(&floppy_usage_lock, flags);
 	usage_count--;
 	spin_unlock_irqrestore(&floppy_usage_lock, flags);
@@ -4501,10 +4528,8 @@ static void floppy_release_irq_and_dma(void)
 #endif
 	old_fdc = fdc;
 	for (fdc = 0; fdc < N_FDC; fdc++)
-		if (FDCS->address != -1) {
-			release_region(FDCS->address + 2, 4);
-			release_region(FDCS->address + 7, 1);
-		}
+		if (FDCS->address != -1)
+			floppy_release_regions(fdc);
 	fdc = old_fdc;
 }