[PATCH v4 1/9] hw/sd: ssi-sd: Support multiple block read

[Bin Meng <bmeng.cn@gmail.com>]

From: Bin Meng <bin.meng@windriver.com>

In the case of a multiple block read operation every transferred
block has its suffix of CRC16. Update the state machine logic to
handle multiple block read.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
[PMD: Change VMState version id 5 -> 6]
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---

(no changes since v1)

 hw/sd/ssi-sd.c | 42 +++++++++++++++++++++++++++++++++---------
 1 file changed, 33 insertions(+), 9 deletions(-)

diff --git a/hw/sd/ssi-sd.c b/hw/sd/ssi-sd.c
index be1bb10164..6d20a240c6 100644
--- a/hw/sd/ssi-sd.c
+++ b/hw/sd/ssi-sd.c
@@ -52,6 +52,7 @@ struct ssi_sd_state {
     uint8_t cmdarg[4];
     uint8_t response[5];
     uint16_t crc16;
+    int32_t read_bytes;
     int32_t arglen;
     int32_t response_pos;
     int32_t stopping;
@@ -88,11 +89,26 @@ static uint32_t ssi_sd_transfer(SSIPeripheral *dev, uint32_t val)
 {
     ssi_sd_state *s = SSI_SD(dev);
 
-    /* Special case: allow CMD12 (STOP TRANSMISSION) while reading data.  */
-    if (s->mode == SSI_SD_DATA_READ && val == 0x4c) {
-        s->mode = SSI_SD_CMD;
-        /* There must be at least one byte delay before the card responds.  */
-        s->stopping = 1;
+    /*
+     * Special case: allow CMD12 (STOP TRANSMISSION) while reading data.
+     *
+     * See "Physical Layer Specification Version 8.00" chapter 7.5.2.2,
+     * to avoid conflict between CMD12 response and next data block,
+     * timing of CMD12 should be controlled as follows:
+     *
+     * - CMD12 issued at the timing that end bit of CMD12 and end bit of
+     *   data block is overlapped
+     * - CMD12 issued after one clock cycle after host receives a token
+     *   (either Start Block token or Data Error token)
+     *
+     * We need to catch CMD12 in all of the data read states.
+     */
+    if (s->mode >= SSI_SD_PREP_DATA && s->mode <= SSI_SD_DATA_CRC16) {
+        if (val == 0x4c) {
+            s->mode = SSI_SD_CMD;
+            /* There must be at least one byte delay before the card responds */
+            s->stopping = 1;
+        }
     }
 
     switch (s->mode) {
@@ -212,8 +228,9 @@ static uint32_t ssi_sd_transfer(SSIPeripheral *dev, uint32_t val)
         return SSI_TOKEN_SINGLE;
     case SSI_SD_DATA_READ:
         val = sdbus_read_byte(&s->sdbus);
+        s->read_bytes++;
         s->crc16 = crc_ccitt_false(s->crc16, (uint8_t *)&val, 1);
-        if (!sdbus_data_ready(&s->sdbus)) {
+        if (!sdbus_data_ready(&s->sdbus) || s->read_bytes == 512) {
             DPRINTF("Data read end\n");
             s->mode = SSI_SD_DATA_CRC16;
         }
@@ -224,7 +241,12 @@ static uint32_t ssi_sd_transfer(SSIPeripheral *dev, uint32_t val)
         s->response_pos++;
         if (s->response_pos == 2) {
             DPRINTF("CRC16 read end\n");
-            s->mode = SSI_SD_CMD;
+            if (s->read_bytes == 512 && s->cmd != 17) {
+                s->mode = SSI_SD_PREP_DATA;
+            } else {
+                s->mode = SSI_SD_CMD;
+            }
+            s->read_bytes = 0;
             s->response_pos = 0;
         }
         return val;
@@ -255,8 +277,8 @@ static int ssi_sd_post_load(void *opaque, int version_id)
 
 static const VMStateDescription vmstate_ssi_sd = {
     .name = "ssi_sd",
-    .version_id = 5,
-    .minimum_version_id = 5,
+    .version_id = 6,
+    .minimum_version_id = 6,
     .post_load = ssi_sd_post_load,
     .fields = (VMStateField []) {
         VMSTATE_UINT32(mode, ssi_sd_state),
@@ -264,6 +286,7 @@ static const VMStateDescription vmstate_ssi_sd = {
         VMSTATE_UINT8_ARRAY(cmdarg, ssi_sd_state, 4),
         VMSTATE_UINT8_ARRAY(response, ssi_sd_state, 5),
         VMSTATE_UINT16(crc16, ssi_sd_state),
+        VMSTATE_INT32(read_bytes, ssi_sd_state),
         VMSTATE_INT32(arglen, ssi_sd_state),
         VMSTATE_INT32(response_pos, ssi_sd_state),
         VMSTATE_INT32(stopping, ssi_sd_state),
@@ -316,6 +339,7 @@ static void ssi_sd_reset(DeviceState *dev)
     memset(s->cmdarg, 0, sizeof(s->cmdarg));
     memset(s->response, 0, sizeof(s->response));
     s->crc16 = 0;
+    s->read_bytes = 0;
     s->arglen = 0;
     s->response_pos = 0;
     s->stopping = 0;
-- 
2.25.1