hw/sd.c: Correct handling of type B SD status bits

Correct how we handle the type B ("cleared on valid command")
status bits. In particular, the CURRENT_STATE bits in a response
should be the state of the card when it received that command,
not the state when it received the preceding command. (This is
one of the issues noted in LP:597641.)
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NAndrzej Zaborowski <andrew.zaborowski@intel.com>

hw/sd.c

@@ -104,7 +104,7 @@ struct SDState {
     int enable;
 };
 
-static void sd_set_status(SDState *sd)
+static void sd_set_mode(SDState *sd)
 {
     switch (sd->state) {
     case sd_inactive_state:
@@ -126,9 +126,6 @@ static void sd_set_status(SDState *sd)
         sd->mode = sd_data_transfer_mode;
         break;
     }
-
-    sd->card_status &= ~CURRENT_STATE;
-    sd->card_status |= sd->state << 9;
 }
 
 static const sd_cmd_type_t sd_cmd_type[64] = {
@@ -341,13 +338,10 @@ static int sd_req_crc_validate(SDRequest *req)
     return sd_crc7(buffer, 5) != req->crc;	/* TODO */
 }
 
-static void sd_response_r1_make(SDState *sd,
-                                uint8_t *response, uint32_t last_status)
+static void sd_response_r1_make(SDState *sd, uint8_t *response)
 {
-    uint32_t mask = CARD_STATUS_B ^ ILLEGAL_COMMAND;
-    uint32_t status;
-
-    status = (sd->card_status & ~mask) | (last_status & mask);
+    uint32_t status = sd->card_status;
+    /* Clear the "clear on read" status bits (except APP_CMD) */
     sd->card_status &= ~CARD_STATUS_C | APP_CMD;
 
     response[0] = (status >> 24) & 0xff;
@@ -1286,7 +1280,7 @@ static int cmd_valid_while_locked(SDState *sd, SDRequest *req)
 
 int sd_do_command(SDState *sd, SDRequest *req,
                   uint8_t *response) {
-    uint32_t last_status = sd->card_status;
+    int last_state;
     sd_rsp_type_t rtype;
     int rsplen;
 
@@ -1300,10 +1294,7 @@ int sd_do_command(SDState *sd, SDRequest *req,
         goto send_response;
     }
 
-    sd->card_status &= ~CARD_STATUS_B;
-    sd_set_status(sd);
-
-    if (last_status & CARD_IS_LOCKED) {
+    if (sd->card_status & CARD_IS_LOCKED) {
         if (!cmd_valid_while_locked(sd, req)) {
             sd->card_status |= ILLEGAL_COMMAND;
             fprintf(stderr, "SD: Card is locked\n");
@@ -1312,7 +1303,10 @@ int sd_do_command(SDState *sd, SDRequest *req,
         }
     }
 
-    if (last_status & APP_CMD) {
+    last_state = sd->state;
+    sd_set_mode(sd);
+
+    if (sd->card_status & APP_CMD) {
         rtype = sd_app_command(sd, *req);
         sd->card_status &= ~APP_CMD;
     } else
@@ -1320,15 +1314,20 @@ int sd_do_command(SDState *sd, SDRequest *req,
 
     if (rtype == sd_illegal) {
         sd->card_status |= ILLEGAL_COMMAND;
+    } else {
+        /* Valid command, we can update the 'state before command' bits.
+         * (Do this now so they appear in r1 responses.)
+         */
+        sd->current_cmd = req->cmd;
+        sd->card_status &= ~CURRENT_STATE;
+        sd->card_status |= (last_state << 9);
     }
 
-    sd->current_cmd = req->cmd;
-
 send_response:
     switch (rtype) {
     case sd_r1:
     case sd_r1b:
-        sd_response_r1_make(sd, response, last_status);
+        sd_response_r1_make(sd, response);
         rsplen = 4;
         break;
 
@@ -1364,6 +1363,13 @@ send_response:
         break;
     }
 
+    if (rtype != sd_illegal) {
+        /* Clear the "clear on valid command" status bits now we've
+         * sent any response
+         */
+        sd->card_status &= ~CARD_STATUS_B;
+    }
+
 #ifdef DEBUG_SD
     if (rsplen) {
         int i;