powerpc: rtas: clean up time handling

The to_tm() helper function operates on a signed integer for the time,
so it will suffer from overflow in 2038, even on 64-bit kernels.

Rather than fix that function, this replaces its use in the rtas
procfs implementation with the standard rtc_time64_to_tm() helper
that is very similar but is not affected by the overflow.

In order to actually support long times, the parser function gets
changed to 64-bit user input and output as well. Note that the tm_mon
and tm_year representation is slightly different, so we have to manually
add an offset here.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/rtas-proc.c

@@ -280,7 +280,7 @@ static int __init proc_rtas_init(void)
 
 __initcall(proc_rtas_init);
 
-static int parse_number(const char __user *p, size_t count, unsigned long *val)
+static int parse_number(const char __user *p, size_t count, u64 *val)
 {
 	char buf[40];
 	char *end;
@@ -293,7 +293,7 @@ static int parse_number(const char __user *p, size_t count, unsigned long *val)
 
 	buf[count] = 0;
 
-	*val = simple_strtoul(buf, &end, 10);
+	*val = simple_strtoull(buf, &end, 10);
 	if (*end && *end != '\n')
 		return -EINVAL;
 
@@ -307,17 +307,17 @@ static ssize_t ppc_rtas_poweron_write(struct file *file,
 		const char __user *buf, size_t count, loff_t *ppos)
 {
 	struct rtc_time tm;
-	unsigned long nowtime;
+	time64_t nowtime;
 	int error = parse_number(buf, count, &nowtime);
 	if (error)
 		return error;
 
 	power_on_time = nowtime; /* save the time */
 
-	to_tm(nowtime, &tm);
+	rtc_time64_to_tm(nowtime, &tm);
 
 	error = rtas_call(rtas_token("set-time-for-power-on"), 7, 1, NULL, 
-			tm.tm_year, tm.tm_mon, tm.tm_mday, 
+			tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
 			tm.tm_hour, tm.tm_min, tm.tm_sec, 0 /* nano */);
 	if (error)
 		printk(KERN_WARNING "error: setting poweron time returned: %s\n", 
@@ -373,14 +373,14 @@ static ssize_t ppc_rtas_clock_write(struct file *file,
 		const char __user *buf, size_t count, loff_t *ppos)
 {
 	struct rtc_time tm;
-	unsigned long nowtime;
+	time64_t nowtime;
 	int error = parse_number(buf, count, &nowtime);
 	if (error)
 		return error;
 
-	to_tm(nowtime, &tm);
+	rtc_time64_to_tm(nowtime, &tm);
 	error = rtas_call(rtas_token("set-time-of-day"), 7, 1, NULL, 
-			tm.tm_year, tm.tm_mon, tm.tm_mday, 
+			tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
 			tm.tm_hour, tm.tm_min, tm.tm_sec, 0);
 	if (error)
 		printk(KERN_WARNING "error: setting the clock returned: %s\n", 
@@ -401,8 +401,8 @@ static int ppc_rtas_clock_show(struct seq_file *m, void *v)
 		unsigned int year, mon, day, hour, min, sec;
 		year = ret[0]; mon  = ret[1]; day  = ret[2];
 		hour = ret[3]; min  = ret[4]; sec  = ret[5];
-		seq_printf(m, "%lu\n",
-				mktime(year, mon, day, hour, min, sec));
+		seq_printf(m, "%lld\n",
+				mktime64(year, mon, day, hour, min, sec));
 	}
 	return 0;
 }
@@ -731,7 +731,7 @@ static void get_location_code(struct seq_file *m, struct individual_sensor *s,
 static ssize_t ppc_rtas_tone_freq_write(struct file *file,
 		const char __user *buf, size_t count, loff_t *ppos)
 {
-	unsigned long freq;
+	u64 freq;
 	int error = parse_number(buf, count, &freq);
 	if (error)
 		return error;
@@ -756,7 +756,7 @@ static int ppc_rtas_tone_freq_show(struct seq_file *m, void *v)
 static ssize_t ppc_rtas_tone_volume_write(struct file *file,
 		const char __user *buf, size_t count, loff_t *ppos)
 {
-	unsigned long volume;
+	u64 volume;
 	int error = parse_number(buf, count, &volume);
 	if (error)
 		return error;