[PULL v2 06/41] hw/sd/sd: Allow multi-byte read/write for generic paths

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

From: Christian Speich <c.speich@avm.de>

Paths that use sd_generic_write/read_data can now write/read multiple
bytes with one call.

Signed-off-by: Christian Speich <c.speich@avm.de>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20260417-sdcard-performance-b4-v4-2-119e66be10c2@avm.de>
[PMD: Access &sd->data[sd->data_offset] in sd_generic_read/write_data]
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 hw/sd/sd.c | 62 ++++++++++++++++++++++++++++++------------------------
 1 file changed, 35 insertions(+), 27 deletions(-)

diff --git a/hw/sd/sd.c b/hw/sd/sd.c
index c0b89735f69..11f6b91576a 100644
--- a/hw/sd/sd.c
+++ b/hw/sd/sd.c
@@ -1610,7 +1610,7 @@ static sd_rsp_type_t sd_cmd_optional(SDState *sd, SDRequest req)
     return sd_illegal;
 }
 
-/* Configure fields for following sd_generic_write_byte() calls */
+/* Configure fields for following sd_generic_write_data() calls */
 static sd_rsp_type_t sd_cmd_to_receivingdata(SDState *sd, SDRequest req,
                                              uint64_t start, size_t size)
 {
@@ -1625,7 +1625,7 @@ static sd_rsp_type_t sd_cmd_to_receivingdata(SDState *sd, SDRequest req,
     return sd_r1;
 }
 
-/* Configure fields for following sd_generic_read_byte() calls */
+/* Configure fields for following sd_generic_read_data() calls */
 static sd_rsp_type_t sd_cmd_to_sendingdata(SDState *sd, SDRequest req,
                                            uint64_t start,
                                            const void *data, size_t size)
@@ -2615,11 +2615,15 @@ send_response:
 }
 
 /* Return true if buffer is consumed. Configured by sd_cmd_to_receivingdata() */
-static bool sd_generic_write_byte(SDState *sd, uint8_t value)
+static bool sd_generic_write_data(SDState *sd, const void *buf, size_t *len)
 {
-    sd->data[sd->data_offset] = value;
+    size_t to_write = MIN(sd->data_size - sd->data_offset, *len);
 
-    if (++sd->data_offset >= sd->data_size) {
+    memcpy(&sd->data[sd->data_offset], buf, to_write);
+    sd->data_offset += to_write;
+    *len = to_write;
+
+    if (sd->data_offset >= sd->data_size) {
         sd->state = sd_transfer_state;
         return true;
     }
@@ -2627,11 +2631,15 @@ static bool sd_generic_write_byte(SDState *sd, uint8_t value)
 }
 
 /* Return true when buffer is consumed. Configured by sd_cmd_to_sendingdata() */
-static bool sd_generic_read_byte(SDState *sd, uint8_t *value)
+static bool sd_generic_read_data(SDState *sd, void *buf, size_t *len)
 {
-    *value = sd->data[sd->data_offset];
+    size_t to_read = MIN(sd->data_size - sd->data_offset, *len);
 
-    if (++sd->data_offset >= sd->data_size) {
+    memcpy(buf, &sd->data[sd->data_offset], to_read);
+    sd->data_offset += to_read;
+    *len = to_read;
+
+    if (sd->data_offset >= sd->data_size) {
         sd->state = sd_transfer_state;
         return true;
     }
@@ -2658,18 +2666,12 @@ static size_t sd_write_data(SDState *sd, const void *buf, size_t length)
     if (sd->card_status & (ADDRESS_ERROR | WP_VIOLATION))
         return length;
 
-    /*
-     * Only read one byte at a time. We will be called again with the
-     * remaining.
-     */
-    length = 1;
-
     trace_sdcard_write_data(sd->proto->name,
                             sd->last_cmd_name,
                             sd->current_cmd, sd->data_offset, value[0]);
     switch (sd->current_cmd) {
     case 24:  /* CMD24:  WRITE_SINGLE_BLOCK */
-        if (sd_generic_write_byte(sd, value[0])) {
+        if (sd_generic_write_data(sd, buf, &length)) {
             /* TODO: Check CRC before committing */
             sd->state = sd_programming_state;
             sd_blk_write(sd, sd->data_start, sd->data_offset);
@@ -2681,6 +2683,12 @@ static size_t sd_write_data(SDState *sd, const void *buf, size_t length)
         break;
 
     case 25:  /* CMD25:  WRITE_MULTIPLE_BLOCK */
+        /*
+         * Only read one byte at a time. We will be called again with the
+         * remaining.
+         */
+        length = 1;
+
         if (sd->data_offset == 0) {
             /* Start of the block - let's check the address is valid */
             if (!address_in_range(sd, "WRITE_MULTIPLE_BLOCK",
@@ -2724,7 +2732,7 @@ static size_t sd_write_data(SDState *sd, const void *buf, size_t length)
         break;
 
     case 26:  /* CMD26:  PROGRAM_CID */
-        if (sd_generic_write_byte(sd, value[0])) {
+        if (sd_generic_write_data(sd, buf, &length)) {
             /* TODO: Check CRC before committing */
             sd->state = sd_programming_state;
             for (i = 0; i < sizeof(sd->cid); i ++)
@@ -2742,7 +2750,7 @@ static size_t sd_write_data(SDState *sd, const void *buf, size_t length)
         break;
 
     case 27:  /* CMD27:  PROGRAM_CSD */
-        if (sd_generic_write_byte(sd, value[0])) {
+        if (sd_generic_write_data(sd, buf, &length)) {
             /* TODO: Check CRC before committing */
             sd->state = sd_programming_state;
             for (i = 0; i < sizeof(sd->csd); i ++)
@@ -2765,7 +2773,7 @@ static size_t sd_write_data(SDState *sd, const void *buf, size_t length)
         break;
 
     case 42:  /* CMD42:  LOCK_UNLOCK */
-        if (sd_generic_write_byte(sd, value[0])) {
+        if (sd_generic_write_data(sd, buf, &length)) {
             /* TODO: Check CRC before committing */
             sd->state = sd_programming_state;
             sd_lock_command(sd);
@@ -2775,7 +2783,7 @@ static size_t sd_write_data(SDState *sd, const void *buf, size_t length)
         break;
 
     case 56:  /* CMD56:  GEN_CMD */
-        sd_generic_write_byte(sd, value[0]);
+        sd_generic_write_data(sd, buf, &length);
         break;
 
     default:
@@ -2810,12 +2818,6 @@ static size_t sd_read_data(SDState *sd, void *buf, size_t length)
         return length;
     }
 
-    /*
-     * We will only read one byte at a time. We will be called again with the
-     * remaining buffer.
-     */
-    length = 1;
-
     io_len = sd_blk_len(sd);
 
     trace_sdcard_read_data(sd->proto->name,
@@ -2833,10 +2835,16 @@ static size_t sd_read_data(SDState *sd, void *buf, size_t length)
     case 30: /* CMD30:  SEND_WRITE_PROT */
     case 51: /* ACMD51: SEND_SCR */
     case 56: /* CMD56:  GEN_CMD */
-        sd_generic_read_byte(sd, value);
+        sd_generic_read_data(sd, buf, &length);
         break;
 
     case 18:  /* CMD18:  READ_MULTIPLE_BLOCK */
+        /*
+         * We will only read one byte at a time. We will be called again with
+         * the remaining buffer.
+         */
+        length = 1;
+
         if (sd->data_offset == 0) {
             if (!address_in_range(sd, "READ_MULTIPLE_BLOCK",
                                   sd->data_start, io_len)) {
@@ -2869,7 +2877,7 @@ static size_t sd_read_data(SDState *sd, void *buf, size_t length)
     default:
         qemu_log_mask(LOG_GUEST_ERROR, "%s: DAT read illegal for command %s\n",
                                        __func__, sd->last_cmd_name);
-        *value = dummy_byte;
+        memset(buf, dummy_byte, length);
     }
 
     return length;
-- 
2.53.0