Re: [PATCH] POWERPC: Added RTC support for mpc8313RDB and utilize "clock-frequency"

On Tue, 17 Jul 2007 11:36:45 -0500
Scott Wood [off-list ref] wrote:

On Tue, Jul 17, 2007 at 04:49:13AM +0400, Vitaly Bordug wrote:

quoted

+	np = of_find_node_by_type(NULL, "cpu");
+	if (np != 0) {
+		const unsigned int *fp =
+			get_property(np, "clock-frequency", NULL);
+		if (fp != 0)
+			loops_per_jiffy = *fp / HZ;
+		else
+			loops_per_jiffy = 50000000 / HZ;
+		of_node_put(np);
+	}

This is not necessary.  It's only used for /proc/cpuinfo (delays are done
using tb_ticks_per_usec), and it'll be overwritten by the generic
calibrate_delay() anyway.

We should be removing this from board files that have it, not adding it
to ones that don't.

Yet many boards still have this stuff (like pretty recent 86xx) - should
we at least add some comments or clean that up?

quoted

+#if defined (CONFIG_SENSORS_DS1337) && defined (CONFIG_I2C)
+
+extern int ds1337_do_command(int id, int cmd, void *arg);
+extern spinlock_t rtc_lock;
+#define DS1337_GET_DATE		0
+#define DS1337_SET_DATE		1
+
+static void mpc8313rdb_get_rtc_time(struct rtc_time *tm)
+{
+	int result;
+
+	result = ds1337_do_command(0, DS1337_GET_DATE, tm);
+
+	if (result == 0)
+		result = mktime(tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec);
+}
+
+static int mpc8313rdb_set_rtc_time(struct rtc_time *tm)
+{
+	int result;
+
+	result = ds1337_do_command(0, DS1337_SET_DATE, tm);
+
+	return result;
+}
+
+static int __init rtc_hookup(void)
+{
+	ppc_md.get_rtc_time = mpc8313rdb_get_rtc_time;
+	ppc_md.set_rtc_time = mpc8313rdb_set_rtc_time;
+	return 0;
+}
+late_initcall(rtc_hookup);
+#endif

Please don't do this; drivers/i2c/chips/ds1337.c is deprecated.  You
should be using the RTC-class driver in drivers/rtc/rtc-ds1307.c, which
has a non-device-specific API that can be used.

The ppc_md RTC functions should really just go away, though -- setting
the clock on bootup can be done by generic code, and periodically
updating the RTC when using NTP can be done from userspace.

If those ppc_md hookups would be declared deprecated, there's no much sense in the upper,
apparently. But I am not sure they will be... I'm inclined to let this patch floating since
interacting with rtc class from within BSP code just does not worth it.

-- 
Sincerely, 
Vitaly