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@xxxxxxxxxxxxxx>
---
-v3: Make internal cmd0 helper static
-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..5fe7c2a 100644
--- a/mmc_cmds.c
+++ b/mmc_cmds.c
@@ -3044,3 +3044,54 @@ out:
close(dev_fd);
return ret;
}
+
+static void issue_cmd0(char *device, __u32 arg)
+{
+ 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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