From: Daniel González Cabanelas <dgcbueu@gmail.com>
Subject: [PATCH 1/2] rtc: rs5c372: support alarms up to 1 week

The Ricoh R2221x, R2223x, RS5C372, RV5C387A chips can handle 1 week
alarms.

Read the "wday" alarm register and convert it to a date to support up 1
week in our driver.

Signed-off-by: Daniel González Cabanelas <dgcbueu@gmail.com>
---
 drivers/rtc/rtc-rs5c372.c | 48 ++++++++++++++++++++++++++++++++++-----
 1 file changed, 42 insertions(+), 6 deletions(-)

--- a/drivers/rtc/rtc-rs5c372.c
+++ b/drivers/rtc/rtc-rs5c372.c
@@ -393,7 +393,9 @@ static int rs5c_read_alarm(struct device
 {
 	struct i2c_client	*client = to_i2c_client(dev);
 	struct rs5c372		*rs5c = i2c_get_clientdata(client);
-	int			status;
+	int			status, wday_offs;
+	struct rtc_time 	rtc;
+	unsigned long 		alarm_secs;
 
 	status = rs5c_get_regs(rs5c);
 	if (status < 0)
@@ -403,6 +405,30 @@ static int rs5c_read_alarm(struct device
 	t->time.tm_sec = 0;
 	t->time.tm_min = bcd2bin(rs5c->regs[RS5C_REG_ALARM_A_MIN] & 0x7f);
 	t->time.tm_hour = rs5c_reg2hr(rs5c, rs5c->regs[RS5C_REG_ALARM_A_HOURS]);
+	t->time.tm_wday = ffs(rs5c->regs[RS5C_REG_ALARM_A_WDAY] & 0x7f) - 1;
+
+	/* determine the day, month and year based on alarm wday, taking as a
+	 * reference the current time from the rtc
+	 */
+	status = rs5c372_rtc_read_time(dev, &rtc);
+	if (status < 0)
+		return status;
+
+	wday_offs = t->time.tm_wday - rtc.tm_wday;
+	alarm_secs = mktime64(rtc.tm_year + 1900,
+			      rtc.tm_mon + 1,
+			      rtc.tm_mday + wday_offs,
+			      t->time.tm_hour,
+			      t->time.tm_min,
+			      t->time.tm_sec);
+
+	if (wday_offs < 0 || (wday_offs == 0 &&
+			      (t->time.tm_hour < rtc.tm_hour ||
+			       (t->time.tm_hour == rtc.tm_hour &&
+				t->time.tm_min <= rtc.tm_min))))
+		alarm_secs += 7 * 86400;
+
+	rtc_time64_to_tm(alarm_secs, &t->time);
 
 	/* ... and status */
 	t->enabled = !!(rs5c->regs[RS5C_REG_CTRL1] & RS5C_CTRL1_AALE);
@@ -417,12 +443,20 @@ static int rs5c_set_alarm(struct device
 	struct rs5c372		*rs5c = i2c_get_clientdata(client);
 	int			status, addr, i;
 	unsigned char		buf[3];
+	struct rtc_time 	rtc_tm;
+	unsigned long 		rtc_secs, alarm_secs;
 
-	/* only handle up to 24 hours in the future, like RTC_ALM_SET */
-	if (t->time.tm_mday != -1
-			|| t->time.tm_mon != -1
-			|| t->time.tm_year != -1)
+	/* chip only can handle alarms up to one week in the future*/
+	status = rs5c372_rtc_read_time(dev, &rtc_tm);
+	if (status)
+		return status;
+	rtc_secs = rtc_tm_to_time64(&rtc_tm);
+	alarm_secs = rtc_tm_to_time64(&t->time);
+	if (alarm_secs >= rtc_secs + 7 * 86400) {
+		dev_err(dev, "%s: alarm maximum is one week in the future (%d)\n",
+			__func__, status);
 		return -EINVAL;
+	}
 
 	/* REVISIT: round up tm_sec */
 
@@ -443,7 +477,9 @@ static int rs5c_set_alarm(struct device
 	/* set alarm */
 	buf[0] = bin2bcd(t->time.tm_min);
 	buf[1] = rs5c_hr2reg(rs5c, t->time.tm_hour);
-	buf[2] = 0x7f;	/* any/all days */
+	/* each bit is the day of the week, 0x7f means all days */
+	buf[2] = (t->time.tm_wday >= 0 && t->time.tm_wday < 7) ?
+		  BIT(t->time.tm_wday) : 0x7f;
 
 	for (i = 0; i < sizeof(buf); i++) {
 		addr = RS5C_ADDR(RS5C_REG_ALARM_A_MIN + i);