Re: [PATCH 08/22] hw/sd: ssi-sd: Support multiple block read (CMD18)

[Alistair Francis]

On Thu, Dec 31, 2020 at 3:41 AM Bin Meng <bmeng.cn@gmail.com> wrote:
>
> From: Bin Meng <bin.meng@windriver.com>
>
> In the case of a multiple block read operation every transfered
> block has its suffix of CRC16. Update the state machine logic to
> handle multiple block read.
>
> This also fixed the wrong command index for STOP_TRANSMISSION,
> the required command to interupt the multiple block read command,
> in the old codes. It should be CMD12 (0x4c), not CMD13 (0x4d).
>
> Signed-off-by: Bin Meng <bin.meng@windriver.com>

Acked-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>
>  hw/sd/ssi-sd.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/hw/sd/ssi-sd.c b/hw/sd/ssi-sd.c
> index 10b0ac2eaf..889260bd8f 100644
> --- a/hw/sd/ssi-sd.c
> +++ b/hw/sd/ssi-sd.c
> @@ -51,6 +51,7 @@ 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;
> @@ -82,7 +83,7 @@ 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 == 0x4d) {
> +    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;
> @@ -200,8 +201,9 @@ static uint32_t ssi_sd_transfer(SSIPeripheral *dev, 
> uint32_t val)
>          return 0xfe;
>      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;
>          }
> @@ -212,7 +214,12 @@ 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_DATA_START;
> +            } else {
> +                s->mode = SSI_SD_CMD;
> +            }
> +            s->read_bytes = 0;
>              s->response_pos = 0;
>          }
>          return val;
> @@ -252,6 +259,7 @@ 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),
> @@ -304,6 +312,7 @@ 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
>
>