[PATCH] rtc: add wakealarm support for rtc-s35390A rtc chip

[Michael Langer <michael.brainbug.langer@googlemail.com>]

Hello,

this patch will add get/set alarm functionality to QNAP TS-219P+ NAS.
I have tested it against a debian wheezy kernel (3.2.23, armel) . After
that I applied the patch against HEAD of linus master branch and
compiled, not tested, successfully.

Regards
Michael

>From a01affe35c049f66fc83ee151d760f3c943aa327 Mon Sep 17 00:00:00 2001
From: Michael Langer <michael.brainbug.langer@googlemail.com>
Date: Sun, 23 Sep 2012 08:27:24 +0200
Subject: [PATCH] rtc: add wakealarm support for rtc-s35390A rtc chip

This adds basic get/set alarm support for the Seiko Instruments S-35390A.
The chip is used on the QNAP TS-219P+ NAS device.

Signed-off-by: Michael Langer <michael.brainbug.langer@googlemail.com>
---
 drivers/rtc/rtc-s35390a.c |  116
+++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 116 insertions(+)

diff --git a/drivers/rtc/rtc-s35390a.c b/drivers/rtc/rtc-s35390a.c
index c9562ce..ef41e7e 100644
--- a/drivers/rtc/rtc-s35390a.c
+++ b/drivers/rtc/rtc-s35390a.c
@@ -19,6 +19,8 @@
 #define S35390A_CMD_STATUS1    0
 #define S35390A_CMD_STATUS2    1
 #define S35390A_CMD_TIME1    2
+#define S35390A_CMD_TIME2    3
+#define S35390A_CMD_INT2_REG1    5
 
 #define S35390A_BYTE_YEAR    0
 #define S35390A_BYTE_MONTH    1
@@ -28,12 +30,23 @@
 #define S35390A_BYTE_MINS    5
 #define S35390A_BYTE_SECS    6
 
+#define S35390A_ALRM_BYTE_WDAY    0
+#define S35390A_ALRM_BYTE_HOURS    1
+#define S35390A_ALRM_BYTE_MINS    2
+
 #define S35390A_FLAG_POC    0x01
 #define S35390A_FLAG_BLD    0x02
 #define S35390A_FLAG_24H    0x40
 #define S35390A_FLAG_RESET    0x80
 #define S35390A_FLAG_TEST    0x01
 
+#define S35390A_INT2_MODE_MASK        0xF0
+
+#define S35390A_INT2_MODE_NOINTR    0x00
+#define S35390A_INT2_MODE_FREQ        0x10
+#define S35390A_INT2_MODE_ALARM        0x40
+#define S35390A_INT2_MODE_PMIN_EDG    0x20
+
 static const struct i2c_device_id s35390a_id[] = {
     { "s35390a", 0 },
     { }
@@ -184,6 +197,104 @@ static int s35390a_get_datetime(struct i2c_client
*client, struct rtc_time *tm)
     return rtc_valid_tm(tm);
 }
 
+static int s35390a_set_alarm(struct i2c_client *client, struct
rtc_wkalrm *alm)
+{
+    struct s35390a *s35390a = i2c_get_clientdata(client);
+    char buf[3], sts = 0;
+    int err, i;
+
+    dev_dbg(&client->dev, "%s: alm is secs=%d, mins=%d, hours=%d
mday=%d, "\
+        "mon=%d, year=%d, wday=%d\n", __func__, alm->time.tm_sec,
+        alm->time.tm_min, alm->time.tm_hour, alm->time.tm_mday,
+        alm->time.tm_mon, alm->time.tm_year, alm->time.tm_wday);
+
+    /* disable interrupt */
+    err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
+    if (err < 0)
+        return err;
+
+    /* clear pending interrupt, if any */
+    err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, &sts, sizeof(sts));
+    if (err < 0)
+        return err;
+
+    if (alm->enabled)
+        sts = S35390A_INT2_MODE_ALARM;
+    else
+        sts = S35390A_INT2_MODE_NOINTR;
+
+    /* This chip expects the bits of each byte to be in reverse order */
+    sts = bitrev8(sts);
+
+    /* set interupt mode*/
+    err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
+    if (err < 0)
+        return err;
+
+    if (alm->time.tm_wday != -1)
+        buf[S35390A_ALRM_BYTE_WDAY] = bin2bcd(alm->time.tm_wday) | 0x80;
+
+    buf[S35390A_ALRM_BYTE_HOURS] = s35390a_hr2reg(s35390a,
+            alm->time.tm_hour) | 0x80;
+    buf[S35390A_ALRM_BYTE_MINS] = bin2bcd(alm->time.tm_min) | 0x80;
+
+    if (alm->time.tm_hour >= 12)
+        buf[S35390A_ALRM_BYTE_HOURS] |= 0x40;
+
+    for (i = 0; i < 3; ++i)
+        buf[i] = bitrev8(buf[i]);
+
+    err = s35390a_set_reg(s35390a, S35390A_CMD_INT2_REG1, buf,
+                                sizeof(buf));
+
+    return err;
+}
+
+static int s35390a_read_alarm(struct i2c_client *client, struct
rtc_wkalrm *alm)
+{
+    struct s35390a *s35390a = i2c_get_clientdata(client);
+    char buf[3], sts;
+    int i, err;
+
+    err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
+    if (err < 0)
+        return err;
+
+    if (bitrev8(sts) != S35390A_INT2_MODE_ALARM)
+        return -EINVAL;
+
+    err = s35390a_get_reg(s35390a, S35390A_CMD_INT2_REG1, buf,
sizeof(buf));
+    if (err < 0)
+        return err;
+
+    /* This chip returns the bits of each byte in reverse order */
+    for (i = 0; i < 3; ++i) {
+        buf[i] = bitrev8(buf[i]);
+        buf[i] &= ~0x80;
+    }
+
+    alm->time.tm_wday = bcd2bin(buf[S35390A_ALRM_BYTE_WDAY]);
+    alm->time.tm_hour = s35390a_reg2hr(s35390a,
+                        buf[S35390A_ALRM_BYTE_HOURS]);
+    alm->time.tm_min = bcd2bin(buf[S35390A_ALRM_BYTE_MINS]);
+
+    dev_dbg(&client->dev, "%s: alm is mins=%d, hours=%d, wday=%d\n",
+            __func__, alm->time.tm_min, alm->time.tm_hour,
+            alm->time.tm_wday);
+
+    return 0;
+}
+
+static int s35390a_rtc_read_alarm(struct device *dev, struct rtc_wkalrm
*alm)
+{
+    return s35390a_read_alarm(to_i2c_client(dev), alm);
+}
+
+static int s35390a_rtc_set_alarm(struct device *dev, struct rtc_wkalrm
*alm)
+{
+    return s35390a_set_alarm(to_i2c_client(dev), alm);
+}
+
 static int s35390a_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
     return s35390a_get_datetime(to_i2c_client(dev), tm);
@@ -197,6 +308,9 @@ static int s35390a_rtc_set_time(struct device *dev,
struct rtc_time *tm)
 static const struct rtc_class_ops s35390a_rtc_ops = {
     .read_time    = s35390a_rtc_read_time,
     .set_time    = s35390a_rtc_set_time,
+    .set_alarm    = s35390a_rtc_set_alarm,
+    .read_alarm    = s35390a_rtc_read_alarm,
+
 };
 
 static struct i2c_driver s35390a_driver;
@@ -261,6 +375,8 @@ static int s35390a_probe(struct i2c_client *client,
     if (s35390a_get_datetime(client, &tm) < 0)
         dev_warn(&client->dev, "clock needs to be set\n");
 
+    device_set_wakeup_capable(&client->dev, 1);
+
     s35390a->rtc = rtc_device_register(s35390a_driver.driver.name,
                 &client->dev, &s35390a_rtc_ops, THIS_MODULE);
 
-- 
1.7.10.4