S-35390A RTC: bring the driver back, handle 12-hour mode

The S-35390A keeps the hour either as 0-23 or - its default after a
power-on reset - as 0-11 plus a p.m. flag, selected by the 12/24 bit of
status register 1. The driver assumed 24-hour mode and never set it: it
masked the p.m. flag off, so on a chip left in 12-hour mode every
afternoon read as morning, and writing an afternoon time stored an
out-of-range hour.

Read the mode in rtc_init() and convert the hour both ways. The chip's
mode is left alone, as another firmware on the same player may depend on
it - the Samsung YP-CP3's original firmware runs it in 12-hour mode and
never touches the bit. If the status register cannot be read, the driver
keeps assuming 24-hour mode, as before.

Upstream removed the driver with its only users, the Meizu M3/M6 and
Samsung YP-S3 ports (1a33d7990a); the Samsung YP-CP3 needs it, so it
comes back here, with RTC_S35390A and its SOURCES entry.

Also pick the I2C header by CONFIG_I2C, so rk27xx targets can use the
driver; i2c_read()/i2c_write() have the same shape there.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Change-Id: I54d8c8cfaa1b88237f6c4b08d2a510ec9fce8ec5

firmware/SOURCES

@@ -502,6 +502,8 @@ drivers/rtc/rtc_jz4740.c
 drivers/rtc/rtc_jz4760.c
 #elif (CONFIG_RTC == RTC_X1000)
 drivers/rtc/rtc_x1000.c
+#elif (CONFIG_RTC == RTC_S35390A)
+drivers/rtc/rtc_s35390a.c
 #elif (CONFIG_RTC == RTC_S35380A)
 drivers/rtc/rtc_s35380a.c
 #elif (CONFIG_RTC == RTC_D2)

firmware/drivers/rtc/rtc_s35390a.c

@@ -0,0 +1,145 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ *
+ * Copyright (C) 2009 by Bertrik Sikken
+ * Copyright (C) 2008 by Robert Kukla
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+#include "config.h"
+#include "rtc.h"
+#if CONFIG_I2C == I2C_S5L8700
+#include "i2c-s5l8700.h"
+#elif CONFIG_I2C == I2C_RK27XX
+#include "i2c-rk27xx.h"
+#endif
+#include "timefuncs.h"
+
+/*  Driver for the Seiko S35390A real-time clock chip with i2c interface
+
+    This driver was derived from rtc_mr100.c and adapted for the S35390A
+    used in the Meizu M3 (and possibly others).
+ */
+
+#define RTC_ADDR   0x60
+
+#define STATUS_REG1     0
+#define STATUS_REG2     1
+#define REALTIME_DATA1  2
+#define REALTIME_DATA2  3
+#define INT1_REG        4
+#define INT2_REG        5
+#define CLOCK_CORR_REG  6
+#define FREE_REG        7
+
+/* bits, once reversed into the usual order */
+#define STATUS1_24H     (1 << 1)    /* 1 = 24-hour, 0 = 12-hour (reset) */
+#define HOUR_PM         (1 << 6)
+
+/* The chip keeps the hour as 0-23 or, the default after a power-on reset,
+ * as 0-11 plus the p.m. flag. The mode is left as found - another firmware
+ * on the same player may expect it - and the hour converted instead. */
+static bool mode_24h = true;
+
+
+static void reverse_bits(unsigned char* v, int size)
+{
+    static const unsigned char flipnibble[] =
+        {0x00, 0x08, 0x04, 0x0C, 0x02, 0x0A, 0x06, 0x0E,
+         0x01, 0x09, 0x05, 0x0D, 0x03, 0x0B, 0x07, 0x0F};
+
+    for (int i = 0; i < size; i++) {
+        v[i] = (flipnibble[v[i] & 0x0F] << 4) |
+                flipnibble[(v[i] >> 4) & 0x0F];
+    }
+}
+
+void rtc_init(void)
+{
+    unsigned char status;
+
+    if (i2c_read(RTC_ADDR | (STATUS_REG1 << 1), -1, 1, &status) == 0)
+    {
+        reverse_bits(&status, 1);
+        mode_24h = (status & STATUS1_24H) != 0;
+    }
+}
+
+int rtc_read_datetime(struct tm *tm)
+{
+    unsigned char buf[7];
+    unsigned int i;
+    bool pm;
+    int ret;
+
+    ret = i2c_read(RTC_ADDR | (REALTIME_DATA1 << 1), -1, sizeof(buf), buf);
+    reverse_bits(buf, sizeof(buf));
+
+    pm = (buf[4] & HOUR_PM) != 0;
+    buf[4] &= 0x3f; /* mask out p.m. flag */
+
+    for (i = 0; i < sizeof(buf); i++)
+        buf[i] = BCD2DEC(buf[i]);
+
+    tm->tm_sec = buf[6];
+    tm->tm_min = buf[5];
+    tm->tm_hour = buf[4];
+    if (!mode_24h && pm)
+    {
+        tm->tm_hour += 12;
+    }
+    tm->tm_mday = buf[2];
+    tm->tm_mon = buf[1] - 1;
+    tm->tm_year = buf[0] + 100;
+
+    set_day_of_week(tm);
+    set_day_of_year(tm);
+
+    return ret;
+}
+
+int rtc_write_datetime(const struct tm *tm)
+{
+    unsigned char buf[7];
+    unsigned int i;
+    int ret;
+
+    buf[6] = tm->tm_sec;
+    buf[5] = tm->tm_min;
+    buf[4] = tm->tm_hour;
+    buf[3] = tm->tm_wday;
+    buf[2] = tm->tm_mday;
+    buf[1] = tm->tm_mon + 1;
+    buf[0] = tm->tm_year - 100;
+
+    if (!mode_24h)
+    {
+        buf[4] = tm->tm_hour % 12;
+    }
+
+    for (i = 0; i < sizeof(buf); i++)
+        buf[i] = DEC2BCD(buf[i]);
+
+    if (!mode_24h && tm->tm_hour >= 12)
+    {
+        buf[4] |= HOUR_PM;
+    }
+
+    reverse_bits(buf, sizeof(buf));
+    ret = i2c_write(RTC_ADDR | (REALTIME_DATA1 << 1), -1, sizeof(buf), buf);
+
+    return ret;
+}
+

firmware/export/config.h

@@ -339,6 +339,7 @@ Lyre prototype 1 */
 #define RTC_MR100  12
 #define RTC_MC13783  13 /* Freescale MC13783 PMIC */
 #define RTC_S5L8700  14
+#define RTC_S35390A  15
 #define RTC_JZ4740   16 /* Ingenic Jz4740 */
 #define RTC_NANO2G   17 /* This seems to be a PCF5063x */
 #define RTC_D2       18 /* Either PCF50606 or PCF50635 */