pm_smbus: correctly report unclaimed cycles

Without this patch, i2cdetect will report all addresses as present.
With it, only 0x50..0x57 are present.

Before:

         0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
    00:          03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
    10: 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
    20: 20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f
    30: 30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f
    40: 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f
    50: 50 51 52 53 54 55 56 57 58 59 5a 5b 5c 5d 5e 5f
    60: 60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f
    70: 70 71 72 73 74 75 76 77

After:

         0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
    00:          -- -- -- -- -- -- -- -- -- -- -- -- --
    10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    50: 50 51 52 53 54 55 56 57 -- -- -- -- -- -- -- --
    60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    70: -- -- -- -- -- -- -- --
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NAndreas Färber <afaerber@suse.de>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

hw/i2c/pm_smbus.c

@@ -60,59 +60,78 @@ static void smb_transaction(PMSMBus *s)
     uint8_t cmd = s->smb_cmd;
     uint8_t addr = s->smb_addr >> 1;
     I2CBus *bus = s->smbus;
+    int ret;
 
     SMBUS_DPRINTF("SMBus trans addr=0x%02x prot=0x%02x\n", addr, prot);
     /* Transaction isn't exec if STS_DEV_ERR bit set */
     if ((s->smb_stat & STS_DEV_ERR) != 0)  {
-            goto error;
-        }
+        goto error;
+    }
     switch(prot) {
     case 0x0:
-        smbus_quick_command(bus, addr, read);
-        s->smb_stat |= STS_BYTE_DONE | STS_INTR;
-        break;
+        ret = smbus_quick_command(bus, addr, read);
+        goto done;
     case 0x1:
         if (read) {
-            s->smb_data0 = smbus_receive_byte(bus, addr);
+            ret = smbus_receive_byte(bus, addr);
+            goto data8;
         } else {
-            smbus_send_byte(bus, addr, cmd);
+            ret = smbus_send_byte(bus, addr, cmd);
+            goto done;
         }
-        s->smb_stat |= STS_BYTE_DONE | STS_INTR;
-        break;
     case 0x2:
         if (read) {
-            s->smb_data0 = smbus_read_byte(bus, addr, cmd);
+            ret = smbus_read_byte(bus, addr, cmd);
+            goto data8;
         } else {
-            smbus_write_byte(bus, addr, cmd, s->smb_data0);
+            ret = smbus_write_byte(bus, addr, cmd, s->smb_data0);
+            goto done;
         }
-        s->smb_stat |= STS_BYTE_DONE | STS_INTR;
         break;
     case 0x3:
         if (read) {
-            uint16_t val;
-            val = smbus_read_word(bus, addr, cmd);
-            s->smb_data0 = val;
-            s->smb_data1 = val >> 8;
+            ret = smbus_read_word(bus, addr, cmd);
+            goto data16;
         } else {
-            smbus_write_word(bus, addr, cmd, (s->smb_data1 << 8) | s->smb_data0);
+            ret = smbus_write_word(bus, addr, cmd, (s->smb_data1 << 8) | s->smb_data0);
+            goto done;
         }
-        s->smb_stat |= STS_BYTE_DONE | STS_INTR;
         break;
     case 0x5:
         if (read) {
-            s->smb_data0 = smbus_read_block(bus, addr, cmd, s->smb_data);
+            ret = smbus_read_block(bus, addr, cmd, s->smb_data);
+            goto data8;
         } else {
-            smbus_write_block(bus, addr, cmd, s->smb_data, s->smb_data0);
+            ret = smbus_write_block(bus, addr, cmd, s->smb_data, s->smb_data0);
+            goto done;
         }
-        s->smb_stat |= STS_BYTE_DONE | STS_INTR;
         break;
     default:
         goto error;
     }
+    abort();
+
+data16:
+    if (ret < 0) {
+        goto error;
+    }
+    s->smb_data1 = ret >> 8;
+data8:
+    if (ret < 0) {
+        goto error;
+    }
+    s->smb_data0 = ret;
+done:
+    if (ret < 0) {
+        goto error;
+    }
+    s->smb_stat |= STS_BYTE_DONE | STS_INTR;
     return;
 
-  error:
+error:
     s->smb_stat |= STS_DEV_ERR;
+    return;
+
 }
 
 static void smb_ioport_writeb(void *opaque, hwaddr addr, uint64_t val,