1 files changed, 86 insertions, 37 deletions

diff --git a/hw/ds1338.c b/hw/ds1338.c
index d590d9c007..b576d56438 100644
--- a/hw/ds1338.c
+++ b/hw/ds1338.c
@@ -12,39 +12,84 @@
 
 #include "i2c.h"
 
+/* Size of NVRAM including both the user-accessible area and the
+ * secondary register area.
+ */
+#define NVRAM_SIZE 64
+
 typedef struct {
     I2CSlave i2c;
-    time_t offset;
-    struct tm now;
-    uint8_t nvram[56];
-    int ptr;
-    int addr_byte;
+    int64_t offset;
+    uint8_t nvram[NVRAM_SIZE];
+    int32_t ptr;
+    bool addr_byte;
 } DS1338State;
 
+static const VMStateDescription vmstate_ds1338 = {
+    .name = "ds1338",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .minimum_version_id_old = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_I2C_SLAVE(i2c, DS1338State),
+        VMSTATE_INT64(offset, DS1338State),
+        VMSTATE_UINT8_ARRAY(nvram, DS1338State, NVRAM_SIZE),
+        VMSTATE_INT32(ptr, DS1338State),
+        VMSTATE_BOOL(addr_byte, DS1338State),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void capture_current_time(DS1338State *s)
+{
+    /* Capture the current time into the secondary registers
+     * which will be actually read by the data transfer operation.
+     */
+    struct tm now;
+    qemu_get_timedate(&now, s->offset);
+    s->nvram[0] = to_bcd(now.tm_sec);
+    s->nvram[1] = to_bcd(now.tm_min);
+    if (s->nvram[2] & 0x40) {
+        s->nvram[2] = (to_bcd((now.tm_hour % 12)) + 1) | 0x40;
+        if (now.tm_hour >= 12) {
+            s->nvram[2] |= 0x20;
+        }
+    } else {
+        s->nvram[2] = to_bcd(now.tm_hour);
+    }
+    s->nvram[3] = to_bcd(now.tm_wday) + 1;
+    s->nvram[4] = to_bcd(now.tm_mday);
+    s->nvram[5] = to_bcd(now.tm_mon) + 1;
+    s->nvram[6] = to_bcd(now.tm_year - 100);
+}
+
+static void inc_regptr(DS1338State *s)
+{
+    /* The register pointer wraps around after 0x3F; wraparound
+     * causes the current time/date to be retransferred into
+     * the secondary registers.
+     */
+    s->ptr = (s->ptr + 1) & (NVRAM_SIZE - 1);
+    if (!s->ptr) {
+        capture_current_time(s);
+    }
+}
+
 static void ds1338_event(I2CSlave *i2c, enum i2c_event event)
 {
     DS1338State *s = FROM_I2C_SLAVE(DS1338State, i2c);
 
     switch (event) {
     case I2C_START_RECV:
-        qemu_get_timedate(&s->now, s->offset);
-        s->nvram[0] = to_bcd(s->now.tm_sec);
-        s->nvram[1] = to_bcd(s->now.tm_min);
-        if (s->nvram[2] & 0x40) {
-            s->nvram[2] = (to_bcd((s->now.tm_hour % 12)) + 1) | 0x40;
-            if (s->now.tm_hour >= 12) {
-                s->nvram[2] |= 0x20;
-            }
-        } else {
-            s->nvram[2] = to_bcd(s->now.tm_hour);
-        }
-        s->nvram[3] = to_bcd(s->now.tm_wday) + 1;
-        s->nvram[4] = to_bcd(s->now.tm_mday);
-        s->nvram[5] = to_bcd(s->now.tm_mon) + 1;
-        s->nvram[6] = to_bcd(s->now.tm_year - 100);
+        /* In h/w, capture happens on any START condition, not just a
+         * START_RECV, but there is no need to actually capture on
+         * START_SEND, because the guest can't get at that data
+         * without going through a START_RECV which would overwrite it.
+         */
+        capture_current_time(s);
         break;
     case I2C_START_SEND:
-        s->addr_byte = 1;
+        s->addr_byte = true;
         break;
     default:
         break;
@@ -57,7 +102,7 @@ static int ds1338_recv(I2CSlave *i2c)
     uint8_t res;
 
     res  = s->nvram[s->ptr];
-    s->ptr = (s->ptr + 1) & 0xff;
+    inc_regptr(s);
     return res;
 }
 
@@ -65,20 +110,20 @@ static int ds1338_send(I2CSlave *i2c, uint8_t data)
 {
     DS1338State *s = FROM_I2C_SLAVE(DS1338State, i2c);
     if (s->addr_byte) {
-        s->ptr = data;
-        s->addr_byte = 0;
+        s->ptr = data & (NVRAM_SIZE - 1);
+        s->addr_byte = false;
         return 0;
     }
-    s->nvram[s->ptr - 8] = data;
-    if (data < 8) {
-        qemu_get_timedate(&s->now, s->offset);
-        switch(data) {
+    if (s->ptr < 8) {
+        struct tm now;
+        qemu_get_timedate(&now, s->offset);
+        switch(s->ptr) {
         case 0:
             /* TODO: Implement CH (stop) bit.  */
-            s->now.tm_sec = from_bcd(data & 0x7f);
+            now.tm_sec = from_bcd(data & 0x7f);
             break;
         case 1:
-            s->now.tm_min = from_bcd(data & 0x7f);
+            now.tm_min = from_bcd(data & 0x7f);
             break;
         case 2:
             if (data & 0x40) {
@@ -90,27 +135,29 @@ static int ds1338_send(I2CSlave *i2c, uint8_t data)
             } else {
                 data = from_bcd(data);
             }
-            s->now.tm_hour = data;
+            now.tm_hour = data;
             break;
         case 3:
-            s->now.tm_wday = from_bcd(data & 7) - 1;
+            now.tm_wday = from_bcd(data & 7) - 1;
             break;
         case 4:
-            s->now.tm_mday = from_bcd(data & 0x3f);
+            now.tm_mday = from_bcd(data & 0x3f);
             break;
         case 5:
-            s->now.tm_mon = from_bcd(data & 0x1f) - 1;
+            now.tm_mon = from_bcd(data & 0x1f) - 1;
             break;
         case 6:
-            s->now.tm_year = from_bcd(data) + 100;
+            now.tm_year = from_bcd(data) + 100;
             break;
         case 7:
             /* Control register. Currently ignored.  */
             break;
         }
-        s->offset = qemu_timedate_diff(&s->now);
+        s->offset = qemu_timedate_diff(&now);
+    } else {
+        s->nvram[s->ptr] = data;
     }
-    s->ptr = (s->ptr + 1) & 0xff;
+    inc_regptr(s);
     return 0;
 }
 
@@ -121,12 +168,14 @@ static int ds1338_init(I2CSlave *i2c)
 
 static void ds1338_class_init(ObjectClass *klass, void *data)
 {
+    DeviceClass *dc = DEVICE_CLASS(klass);
     I2CSlaveClass *k = I2C_SLAVE_CLASS(klass);
 
     k->init = ds1338_init;
     k->event = ds1338_event;
     k->recv = ds1338_recv;
     k->send = ds1338_send;
+    dc->vmsd = &vmstate_ds1338;
 }
 
 static TypeInfo ds1338_info = {