hw/sd/sd: Allow multi-byte read/write for generic paths
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>
Christian Speich committed
Apr 17, 2026 at 11:51 UTC
eff58d3d9681ab34538a5308047ff6ba1dc6786c
1 file changed
+35
-27
hw/sd/sd.c
+35
-27
@@ -1610,7 +1610,7 @@ static sd_rsp_type_t sd_cmd_optional(SDState *sd, SDRequest req)
1610
return sd_illegal;
1611
}
1612
1613
-/* Configure fields for following sd_generic_write_byte() calls */
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+/* Configure fields for following sd_generic_write_data() calls */
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static sd_rsp_type_t sd_cmd_to_receivingdata(SDState *sd, SDRequest req,
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uint64_t start, size_t size)
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{
@@ -1625,7 +1625,7 @@ static sd_rsp_type_t sd_cmd_to_receivingdata(SDState *sd, SDRequest req,
1625
return sd_r1;
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}
1627
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-/* Configure fields for following sd_generic_read_byte() calls */
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+/* Configure fields for following sd_generic_read_data() calls */
1629
static sd_rsp_type_t sd_cmd_to_sendingdata(SDState *sd, SDRequest req,
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uint64_t start,
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const void *data, size_t size)
@@ -2615,11 +2615,15 @@ send_response:
2615
}
2616
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/* Return true if buffer is consumed. Configured by sd_cmd_to_receivingdata() */
2618
-static bool sd_generic_write_byte(SDState *sd, uint8_t value)
2618
+static bool sd_generic_write_data(SDState *sd, const void *buf, size_t *len)
2619
{
2620
- sd->data[sd->data_offset] = value;
2620
+ size_t to_write = MIN(sd->data_size - sd->data_offset, *len);
2621
2622
- if (++sd->data_offset >= sd->data_size) {
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+ memcpy(&sd->data[sd->data_offset], buf, to_write);
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+ sd->data_offset += to_write;
2624
+ *len = to_write;
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+
2626
+ if (sd->data_offset >= sd->data_size) {
2627
sd->state = sd_transfer_state;
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return true;
2629
}
@@ -2627,11 +2631,15 @@ static bool sd_generic_write_byte(SDState *sd, uint8_t value)
2631
}
2632
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/* Return true when buffer is consumed. Configured by sd_cmd_to_sendingdata() */
2630
-static bool sd_generic_read_byte(SDState *sd, uint8_t *value)
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+static bool sd_generic_read_data(SDState *sd, void *buf, size_t *len)
2635
{
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- *value = sd->data[sd->data_offset];
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+ size_t to_read = MIN(sd->data_size - sd->data_offset, *len);
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+
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+ memcpy(buf, &sd->data[sd->data_offset], to_read);
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+ sd->data_offset += to_read;
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+ *len = to_read;
2641
2634
- if (++sd->data_offset >= sd->data_size) {
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+ if (sd->data_offset >= sd->data_size) {
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sd->state = sd_transfer_state;
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return true;
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}
@@ -2658,18 +2666,12 @@ static size_t sd_write_data(SDState *sd, const void *buf, size_t length)
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if (sd->card_status & (ADDRESS_ERROR | WP_VIOLATION))
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return length;
2668
2661
- /*
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- * Only read one byte at a time. We will be called again with the
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- * remaining.
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- */
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- length = 1;
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-
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trace_sdcard_write_data(sd->proto->name,
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sd->last_cmd_name,
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sd->current_cmd, sd->data_offset, value[0]);
2672
switch (sd->current_cmd) {
2673
case 24: /* CMD24: WRITE_SINGLE_BLOCK */
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- if (sd_generic_write_byte(sd, value[0])) {
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+ if (sd_generic_write_data(sd, buf, &length)) {
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/* TODO: Check CRC before committing */
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sd->state = sd_programming_state;
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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)
2683
break;
2684
2685
case 25: /* CMD25: WRITE_MULTIPLE_BLOCK */
2686
+ /*
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+ * Only read one byte at a time. We will be called again with the
2688
+ * remaining.
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+ */
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+ length = 1;
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+
2692
if (sd->data_offset == 0) {
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/* Start of the block - let's check the address is valid */
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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)
2732
break;
2733
2734
case 26: /* CMD26: PROGRAM_CID */
2727
- if (sd_generic_write_byte(sd, value[0])) {
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+ if (sd_generic_write_data(sd, buf, &length)) {
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/* TODO: Check CRC before committing */
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sd->state = sd_programming_state;
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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)
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break;
2751
2752
case 27: /* CMD27: PROGRAM_CSD */
2745
- if (sd_generic_write_byte(sd, value[0])) {
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+ if (sd_generic_write_data(sd, buf, &length)) {
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/* TODO: Check CRC before committing */
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sd->state = sd_programming_state;
2756
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)
2773
break;
2774
2775
case 42: /* CMD42: LOCK_UNLOCK */
2768
- if (sd_generic_write_byte(sd, value[0])) {
2776
+ if (sd_generic_write_data(sd, buf, &length)) {
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/* TODO: Check CRC before committing */
2778
sd->state = sd_programming_state;
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sd_lock_command(sd);
@@ -2775,7 +2783,7 @@ static size_t sd_write_data(SDState *sd, const void *buf, size_t length)
2783
break;
2784
2785
case 56: /* CMD56: GEN_CMD */
2778
- sd_generic_write_byte(sd, value[0]);
2786
+ sd_generic_write_data(sd, buf, &length);
2787
break;
2788
2789
default:
@@ -2810,12 +2818,6 @@ static size_t sd_read_data(SDState *sd, void *buf, size_t length)
2818
return length;
2819
}
2820
2813
- /*
2814
- * We will only read one byte at a time. We will be called again with the
2815
- * remaining buffer.
2816
- */
2817
- length = 1;
2818
-
2821
io_len = sd_blk_len(sd);
2822
2823
trace_sdcard_read_data(sd->proto->name,
@@ -2833,10 +2835,16 @@ static size_t sd_read_data(SDState *sd, void *buf, size_t length)
2835
case 30: /* CMD30: SEND_WRITE_PROT */
2836
case 51: /* ACMD51: SEND_SCR */
2837
case 56: /* CMD56: GEN_CMD */
2836
- sd_generic_read_byte(sd, value);
2838
+ sd_generic_read_data(sd, buf, &length);
2839
break;
2840
2841
case 18: /* CMD18: READ_MULTIPLE_BLOCK */
2842
+ /*
2843
+ * We will only read one byte at a time. We will be called again with
2844
+ * the remaining buffer.
2845
+ */
2846
+ length = 1;
2847
+
2848
if (sd->data_offset == 0) {
2849
if (!address_in_range(sd, "READ_MULTIPLE_BLOCK",
2850
sd->data_start, io_len)) {
@@ -2869,7 +2877,7 @@ static size_t sd_read_data(SDState *sd, void *buf, size_t length)
2877
default:
2878
qemu_log_mask(LOG_GUEST_ERROR, "%s: DAT read illegal for command %s\n",
2879
__func__, sd->last_cmd_name);
2872
- *value = dummy_byte;
2880
+ memset(buf, dummy_byte, length);
2881
}
2882
2883
return length;