The patch titled
rtc: fall back to requesting only the ports we actually use
has been added to the -mm tree. Its filename is
rtc-fallback-to-requesting-only-the-ports-we-actually-use.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: rtc: fall back to requesting only the ports we actually use
From: Bjorn Helgaas <bjorn.helgaas@xxxxxx>
Firmware like PNPBIOS or ACPI can report the address space consumed by the
RTC. The actual space consumed may be less than the size (RTC_IO_EXTENT)
assumed by the RTC driver.
The PNP core doesn't request resources yet, but I'd like to make it do so.
If/when it does, the RTC_IO_EXTENT request may fail, which prevents the RTC
driver from loading.
Since we only use the RTC index and data registers at RTC_PORT(0) and
RTC_PORT(1), we can fall back to requesting just enough space for those.
If the PNP core requests resources, this results in typical I/O port usage
like this:
0070-0073 : 00:06 <-- PNP device 00:06 responds to 70-73
0070-0071 : rtc <-- RTC driver uses only 70-71
instead of the current:
0070-0077 : rtc <-- RTC_IO_EXTENT == 8
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@xxxxxx>
Cc: Alessandro Zummo <a.zummo@xxxxxxxxxxxx>
Cc: David Brownell <david-b@xxxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/char/rtc.c | 36 ++++++++++++++++++++++++++++------
include/linux/mc146818rtc.h | 3 ++
2 files changed, 33 insertions(+), 6 deletions(-)
diff -puN drivers/char/rtc.c~rtc-fallback-to-requesting-only-the-ports-we-actually-use drivers/char/rtc.c
--- a/drivers/char/rtc.c~rtc-fallback-to-requesting-only-the-ports-we-actually-use
+++ a/drivers/char/rtc.c
@@ -919,12 +919,29 @@ static const struct file_operations rtc_
};
#endif
+static resource_size_t rtc_size;
+
+static struct resource * __init rtc_request_region(resource_size_t size)
+{
+ struct resource *r;
+
+ if (RTC_IOMAPPED)
+ r = request_region(RTC_PORT(0), size, "rtc");
+ else
+ r = request_mem_region(RTC_PORT(0), size, "rtc");
+
+ if (r)
+ rtc_size = size;
+
+ return r;
+}
+
static void rtc_release_region(void)
{
if (RTC_IOMAPPED)
- release_region(RTC_PORT(0), RTC_IO_EXTENT);
+ release_region(RTC_PORT(0), rtc_size);
else
- release_mem_region(RTC_PORT(0), RTC_IO_EXTENT);
+ release_mem_region(RTC_PORT(0), rtc_size);
}
static int __init rtc_init(void)
@@ -977,10 +994,17 @@ found:
}
no_irq:
#else
- if (RTC_IOMAPPED)
- r = request_region(RTC_PORT(0), RTC_IO_EXTENT, "rtc");
- else
- r = request_mem_region(RTC_PORT(0), RTC_IO_EXTENT, "rtc");
+ r = rtc_request_region(RTC_IO_EXTENT);
+
+ /*
+ * If we've already requested a smaller range (for example, because
+ * PNPBIOS or ACPI told us how the device is configured), the request
+ * above might fail because it's too big.
+ *
+ * If so, request just the range we actually use.
+ */
+ if (!r)
+ r = rtc_request_region(RTC_IO_EXTENT_USED);
if (!r) {
#ifdef RTC_IRQ
rtc_has_irq = 0;
diff -puN include/linux/mc146818rtc.h~rtc-fallback-to-requesting-only-the-ports-we-actually-use include/linux/mc146818rtc.h
--- a/include/linux/mc146818rtc.h~rtc-fallback-to-requesting-only-the-ports-we-actually-use
+++ a/include/linux/mc146818rtc.h
@@ -109,8 +109,11 @@ struct cmos_rtc_board_info {
#ifndef ARCH_RTC_LOCATION /* Override by <asm/mc146818rtc.h>? */
#define RTC_IO_EXTENT 0x8
+#define RTC_IO_EXTENT_USED 0x2
#define RTC_IOMAPPED 1 /* Default to I/O mapping. */
+#else
+#define RTC_IO_EXTENT_USED RTC_IO_EXTENT
#endif /* ARCH_RTC_LOCATION */
#endif /* _MC146818RTC_H */
_
Patches currently in -mm which might be from bjorn.helgaas@xxxxxx are
serial-keep-the-dtr-setting-for-serial-console.patch
rtc-release-correct-region-in-error-path.patch
rtc-fallback-to-requesting-only-the-ports-we-actually-use.patch
pnp-simplify-pnp_activate_dev-and-pnp_disable_dev-return-values.patch
-
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
