Hi Finn,
On Thu, Oct 3, 2024 at 5:27 AM Finn Thain <fthain@xxxxxxxxxxxxxx> 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>
Thanks for your patch!
--- 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
This causes a change in behavior on other non-SPARC platforms,
if any out-of-tree platform exists that uses this driver.
So I'd rather use:
#elif defined(CONFIG_VME)
#define YEAR0 70
#else
#define YEAR0 0
#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;
Upon closer look, the driver uses platform data, so a better solution
would be to add the year0 offset to struct m48t59_plat_data.
Another suggestion for improvement, not related to this patch,
would be to differentiate among M48T59, M48T02, and M48T08 by using
platform_driver.id_table and platform_device_id.driver_data, instead
of m48t59_plat_data.type.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
