[PATCHv2] mmc-utils: Add CMD0 softreset and preidle command

CMD0 may be used to see if the hardware can handle a UHS card
that completed the voltage switch. If a UHS card has problems
coming back up after CMD0 your hardware may not support a hard
reset properly.

Signed-off-by: Christian Loehle <cloehle@hyperstone.com>
---
-v2: Use macro for cmd0 argument
Note: A previous version has been discussed as
mmc-utils: Add softreset command for issuing CMD0
but with the addition of preidle I considered this to be
a different patch
mmc.c      | 10 ++++++++++
 mmc.h      |  5 +++++
 mmc_cmds.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 mmc_cmds.h |  2 ++
 4 files changed, 68 insertions(+)

> CMD0 may be used to see if the hardware can handle a UHS card
> that completed the voltage switch. If a UHS card has problems
> coming back up after CMD0 your hardware may not support a hard
> reset properly.
> 
> Signed-off-by: Christian Loehle <cloehle@hyperstone.com>
> ---
> -v2: Use macro for cmd0 argument
> Note: A previous version has been discussed as
> mmc-utils: Add softreset command for issuing CMD0
> but with the addition of preidle I considered this to be
> a different patch
> mmc.c      | 10 ++++++++++
>  mmc.h      |  5 +++++
>  mmc_cmds.c | 51
> +++++++++++++++++++++++++++++++++++++++++++++++++++
>  mmc_cmds.h |  2 ++
>  4 files changed, 68 insertions(+)
> 
> diff --git a/mmc.c b/mmc.c
> index 6c56387..50493f3 100644
> --- a/mmc.c
> +++ b/mmc.c
> @@ -245,6 +245,16 @@ static struct Command commands[] = {
>                 "be 1.",
>         NULL
>         },
> +       { do_softreset, -1,
> +         "softreset", "<device>\n"
> +         "Issues a CMD0 softreset, e.g. for testing if hardware reset for UHS
> works",
> +         NULL
> +       },
> +       { do_preidle, -1,
> +         "preidle", "<device>\n"
> +         "Issues a CMD0 GO_PRE_IDLE",
> +         NULL
> +       },
>         { 0, 0, 0, 0 }
>  };
> 
> diff --git a/mmc.h b/mmc.h
> index daff62c..6511dbc 100644
> --- a/mmc.h
> +++ b/mmc.h
> @@ -21,6 +21,9 @@
>  #include <linux/mmc/ioctl.h>
> 
>  /* From kernel linux/mmc/mmc.h */
> +#define MMC_GO_IDLE_STATE         0   /* bc                          */
> +#define MMC_GO_IDLE_STATE_ARG          0x0
> +#define MMC_GO_PRE_IDLE_STATE_ARG      0xF0F0F0F0
>  #define MMC_SWITCH             6       /* ac   [31:0] See below        R1b */
>  #define MMC_SEND_EXT_CSD       8       /* adtc                         R1  */
>  #define MMC_SEND_STATUS                13      /* ac   [31:16] RCA        R1  */
> @@ -226,6 +229,7 @@
> 
> 
>  /* From kernel linux/mmc/core.h */
> +#define MMC_RSP_NONE   0                       /* no response */
>  #define MMC_RSP_PRESENT        (1 << 0)
>  #define MMC_RSP_136    (1 << 1)                /* 136 bit response */
>  #define MMC_RSP_CRC    (1 << 2)                /* expect valid crc */
> @@ -234,6 +238,7 @@
> 
>  #define MMC_CMD_AC     (0 << 5)
>  #define MMC_CMD_ADTC   (1 << 5)
> +#define MMC_CMD_BC     (2 << 5)
> 
>  #define MMC_RSP_SPI_S1 (1 << 7)                /* one status byte */
>  #define MMC_RSP_SPI_BUSY (1 << 10)             /* card may send busy */
> diff --git a/mmc_cmds.c b/mmc_cmds.c
> index 2957aa9..94e30e0 100644
> --- a/mmc_cmds.c
> +++ b/mmc_cmds.c
> @@ -3044,3 +3044,54 @@ out:
>         close(dev_fd);
>         return ret;
>  }
> +
> +void issue_cmd0(char *device, __u32 arg)
Static ?


Thanks,
Avri

> +{
> +       struct mmc_ioc_cmd idata;
> +       int fd;
> +
> +       fd = open(device, O_RDWR);
> +       if (fd < 0) {
> +               perror("open");
> +               exit(1);
> +       }
> +
> +       memset(&idata, 0, sizeof(idata));
> +       idata.opcode = MMC_GO_IDLE_STATE;
> +       idata.arg = arg;
> +       idata.flags = MMC_RSP_NONE | MMC_CMD_BC;
> +
> +       /* No need to check for error, it is expected */
> +       ioctl(fd, MMC_IOC_CMD, &idata);
> +       close(fd);
> +}
> +
> +int do_softreset(int nargs, char **argv)
> +{
> +       char *device;
> +
> +       if (nargs != 2) {
> +               fprintf(stderr, "Usage: mmc softreset </path/to/mmcblkX>\n");
> +               exit(1);
> +       }
> +
> +       device = argv[1];
> +       issue_cmd0(device, MMC_GO_IDLE_STATE_ARG);
> +
> +       return 0;
> +}
> +
> +int do_preidle(int nargs, char **argv)
> +{
> +       char *device;
> +
> +       if (nargs != 2) {
> +               fprintf(stderr, "Usage: mmc preidle </path/to/mmcblkX>\n");
> +               exit(1);
> +       }
> +
> +       device = argv[1];
> +       issue_cmd0(device, MMC_GO_PRE_IDLE_STATE_ARG);
> +
> +       return 0;
> +}
> diff --git a/mmc_cmds.h b/mmc_cmds.h
> index 0f7c004..faab362 100644
> --- a/mmc_cmds.h
> +++ b/mmc_cmds.h
> @@ -47,3 +47,5 @@ int do_read_cid(int argc, char **argv);
>  int do_read_csd(int argc, char **argv);
>  int do_erase(int nargs, char **argv);
>  int do_general_cmd_read(int nargs, char **argv);
> +int do_softreset(int nargs, char **argv);
> +int do_preidle(int nargs, char **argv);
> --
> 2.37.3
> 
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