releases/2.6.27.5/x86-register-a-platform-rtc-device-if-pnp-doesn-t-describe-it.patch

From cebbert@redhat.com  Tue Nov  4 14:31:31 2008
From: Bjorn Helgaas <bjorn.helgaas@hp.com>
Date: Sun, 26 Oct 2008 18:57:33 -0400
Subject: x86: register a platform RTC device if PNP doesn't describe it
To: stable@kernel.org
Cc: David Brownell <dbrownell@users.sourceforge.net>, Bjorn Helgaas <bjorn.helgaas@hp.com>
Message-ID: <20081026185733.6ad3746f@redhat.com>

From: Bjorn Helgaas <bjorn.helgaas@hp.com>

commit 758a7f7bb86b520aadc484f23da85e547b3bf3d8 upstream

x86: register a platform RTC device if PNP doesn't describe it

Most if not all x86 platforms have an RTC device, but sometimes the RTC
is not exposed as a PNP0b00/PNP0b01/PNP0b02 device in PNPBIOS or ACPI:

    http://bugzilla.kernel.org/show_bug.cgi?id=11580
    https://bugzilla.redhat.com/show_bug.cgi?id=451188

It's best if we can discover the RTC via PNP because then we know
which flavor of device it is, where it lives, and which IRQ it uses.

But if we can't, we should register a platform device using the
compiled-in RTC_PORT/RTC_IRQ resource assumptions.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Reported-by: Rik Theys <rik.theys@esat.kuleuven.be>
Reported-by: shr_msn@yahoo.com.tw
Cc: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 arch/x86/kernel/rtc.c |   22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

--- a/arch/x86/kernel/rtc.c
+++ b/arch/x86/kernel/rtc.c
@@ -223,11 +223,25 @@ static struct platform_device rtc_device
 static __init int add_rtc_cmos(void)
 {
 #ifdef CONFIG_PNP
-	if (!pnp_platform_devices)
-		platform_device_register(&rtc_device);
-#else
+	static const char *ids[] __initconst =
+	    { "PNP0b00", "PNP0b01", "PNP0b02", };
+	struct pnp_dev *dev;
+	struct pnp_id *id;
+	int i;
+
+	pnp_for_each_dev(dev) {
+		for (id = dev->id; id; id = id->next) {
+			for (i = 0; i < ARRAY_SIZE(ids); i++) {
+				if (compare_pnp_id(id, ids[i]) != 0)
+					return 0;
+			}
+		}
+	}
+#endif
+
 	platform_device_register(&rtc_device);
-#endif /* CONFIG_PNP */
+	dev_info(&rtc_device.dev,
+		 "registered platform RTC device (no PNP device found)\n");
 	return 0;
 }
 device_initcall(add_rtc_cmos);