[Qemu-devel] [PATCH 5/?] hw/ds1338.c: Fix handling of DATE (wday) register

[Antoine Mathys]

Per the datasheet, the DATE (wday) register is user defined. Implement this.

Signed-off-by: Antoine Mathys <address@hidden>
---
 hw/ds1338.c |   14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/hw/ds1338.c b/hw/ds1338.c
index 8f85635..c502934 100644
--- a/hw/ds1338.c
+++ b/hw/ds1338.c
@@ -20,6 +20,7 @@
 typedef struct {
     I2CSlave i2c;
     int64_t offset;
+    uint8_t wday_offset;
     uint8_t nvram[NVRAM_SIZE];
     int32_t ptr;
     bool addr_byte;
@@ -33,6 +34,7 @@ static const VMStateDescription vmstate_ds1338 = {
     .fields = (VMStateField[]) {
         VMSTATE_I2C_SLAVE(i2c, DS1338State),
         VMSTATE_INT64(offset, DS1338State),
+        VMSTATE_UINT8(wday_offset, DS1338State),
         VMSTATE_UINT8_ARRAY(nvram, DS1338State, NVRAM_SIZE),
         VMSTATE_INT32(ptr, DS1338State),
         VMSTATE_BOOL(addr_byte, DS1338State),
@@ -62,7 +64,7 @@ static void write_time(DS1338State *s, const struct tm 
*tm)
     } else {
         s->nvram[2] = to_bcd(tm->tm_hour);
     }
-    s->nvram[3] = to_bcd(tm->tm_wday + 1);
+    s->nvram[3] = to_bcd((tm->tm_wday + s->wday_offset) % 7 + 1);
     s->nvram[4] = to_bcd(tm->tm_mday);
     s->nvram[5] = to_bcd(tm->tm_mon + 1);
     s->nvram[6] = to_bcd(tm->tm_year - 100);
@@ -164,7 +166,12 @@ static int ds1338_send(I2CSlave *i2c, uint8_t data)
             }
             break;
         case 3:
-            now.tm_wday = from_bcd(data & 0x07) - 1;
+            {
+                int user_wday = from_bcd(data & 0x07) - 1;
+                if ((user_wday >= 0) && (user_wday <= 6)) {
+                    s->wday_offset = (user_wday - now.tm_wday + 7) % 7;
+                }
+            }
             break;
         case 4:
             now.tm_mday = from_bcd(data & 0x3f);
@@ -194,6 +201,9 @@ static int ds1338_send(I2CSlave *i2c, uint8_t data)

 static int ds1338_init(I2CSlave *i2c)
 {
+    DS1338State *s = FROM_I2C_SLAVE(DS1338State, i2c);
+    s->wday_offset = 0;
+
     return 0;
 }

--
1.7.10.4