On Thu, 3 Oct 2024, Alexandre Belloni wrote:
On 03/10/2024 13:23:22+1000, Finn Thain wrote:
The m48t59 driver is needed by both SPARC and MVME systems. Linux on
MVME uses 1970 as "year zero" rather than 1968 that's used on SPARC.
Add support for the MVME convention. Otherwise, the RTC on non-SPARC
systems can only read and write dates between 1900 and 1999.
Tested-by: Daniel Palmer <daniel@xxxxxxxx>
Signed-off-by: Finn Thain <fthain@xxxxxxxxxxxxxx>
---
drivers/rtc/rtc-m48t59.c | 31 +++++++++++++++----------------
1 file changed, 15 insertions(+), 16 deletions(-)
diff --git a/drivers/rtc/rtc-m48t59.c b/drivers/rtc/rtc-m48t59.c
index f0f6b9b6daec..e2d882ea5c2f 100644
--- a/drivers/rtc/rtc-m48t59.c
+++ b/drivers/rtc/rtc-m48t59.c
@@ -57,6 +57,17 @@ m48t59_mem_readb(struct device *dev, u32 ofs)
return readb(m48t59->ioaddr+ofs);
}
+/*
+ * Sun SPARC machines count years since 1968. MVME machines running Linux
+ * count years since 1970.
+ */
+
+#ifdef CONFIG_SPARC
+#define YEAR0 68
+#else
+#define YEAR0 70
+#endif
+
/*
* NOTE: M48T59 only uses BCD mode
*/
@@ -82,10 +93,7 @@ static int m48t59_rtc_read_time(struct device *dev, struct rtc_time *tm)
dev_dbg(dev, "Century bit is enabled\n");
tm->tm_year += 100; /* one century */
}
-#ifdef CONFIG_SPARC
- /* Sun SPARC machines count years since 1968 */
- tm->tm_year += 68;
-#endif
+ tm->tm_year += YEAR0;
I'm super happy to see someone working on this, while you are it, can
you use m48t59->rtc->start_secs and m48t59->rtc->set_start_time in probe
instead of offsetting tm_year in read_time/set_time so we can later use
device tree or any other mechanism to extend the range?
Sure, I will look into it.
It is super funny because I was telling Geert that I wanted to get rid
of this #ifdef CONFIG_SPARC two weeks ago at LPC. That could indeed then
come from platform data.
I can't test any patches on SPARC, unless there's some way to do so using
QEMU that would satisfy maintainers. (I rely on Daniel to test my patches
on an MVME147 system.)
