[PATCH v4 3/3] i3c: master: Validate GET CCC payload length and retry Direct GET once
From: tze . yee . ng
Date: Tue Jun 30 2026 - 09:22:40 EST
From: Adrian Ng Ho Yin <adrian.ho.yin.ng@xxxxxxxxxx>
Add optional_bytes to struct i3c_ccc_cmd_payload so callers describe
variable-length GET CCC responses. GETMRL and GETMXDS set optional_bytes
at the call site.
Validate GET payload length in i3c_master_send_ccc_cmd_locked() using
actual_len and optional_bytes. Retry failed Direct GET CCCs up to
cmd->retries times (default I3C_CCC_RETRIES) on any error; SET CCCs are
not retried by default.
Add i3c_ccc_cmd_init_retries() and set actual_len in I3C master drivers
on successful GET transfers.
Signed-off-by: Adrian Ng Ho Yin <adrian.ho.yin.ng@xxxxxxxxxx>
Signed-off-by: Tze Yee Ng <tze.yee.ng@xxxxxxxxxx>
---
drivers/i3c/master.c | 92 ++++++++++++++++++++++----
drivers/i3c/master/adi-i3c-master.c | 2 +
drivers/i3c/master/i3c-master-cdns.c | 2 +
drivers/i3c/master/mipi-i3c-hci/core.c | 5 +-
drivers/i3c/master/renesas-i3c.c | 2 +
drivers/i3c/master/svc-i3c-master.c | 4 +-
include/linux/i3c/ccc.h | 7 ++
7 files changed, 98 insertions(+), 16 deletions(-)
diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index 5cd4e5da2233..29dc0793a5a4 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -901,6 +901,8 @@ static void *i3c_ccc_cmd_dest_init(struct i3c_ccc_cmd_dest *dest, u8 addr,
{
dest->addr = addr;
dest->payload.len = payloadlen;
+ dest->payload.actual_len = 0;
+ dest->payload.optional_bytes = 0;
if (payloadlen)
dest->payload.data = kzalloc(payloadlen, GFP_KERNEL);
else
@@ -914,17 +916,55 @@ static void i3c_ccc_cmd_dest_cleanup(struct i3c_ccc_cmd_dest *dest)
kfree(dest->payload.data);
}
-static void i3c_ccc_cmd_init(struct i3c_ccc_cmd *cmd, bool rnw, u8 id,
- struct i3c_ccc_cmd_dest *dests,
- unsigned int ndests)
+static void i3c_ccc_cmd_init_retries(struct i3c_ccc_cmd *cmd, bool rnw, u8 id,
+ struct i3c_ccc_cmd_dest *dests,
+ unsigned int ndests, unsigned int retries)
{
cmd->rnw = rnw ? 1 : 0;
cmd->id = id;
cmd->dests = dests;
cmd->ndests = ndests;
+ cmd->retries = retries;
cmd->err = I3C_ERROR_UNKNOWN;
}
+static void i3c_ccc_cmd_init(struct i3c_ccc_cmd *cmd, bool rnw, u8 id,
+ struct i3c_ccc_cmd_dest *dests,
+ unsigned int ndests)
+{
+ i3c_ccc_cmd_init_retries(cmd, rnw, id, dests, ndests,
+ rnw ? I3C_CCC_RETRIES : 0);
+}
+
+static int i3c_ccc_validate_payload_len(struct i3c_ccc_cmd *cmd)
+{
+ unsigned int i;
+
+ if (!cmd->rnw)
+ return 0;
+
+ for (i = 0; i < cmd->ndests; i++) {
+ struct i3c_ccc_cmd_payload *p = &cmd->dests[i].payload;
+ u16 min_len;
+
+ if (p->optional_bytes > p->len)
+ return -EINVAL;
+
+ if (p->actual_len > p->len)
+ return -EIO;
+
+ if (!p->len)
+ continue;
+
+ min_len = p->len - p->optional_bytes;
+ if (p->actual_len < min_len ||
+ (!p->optional_bytes && p->actual_len != p->len))
+ return -EIO;
+ }
+
+ return 0;
+}
+
/**
* i3c_master_send_ccc_cmd_locked() - send a CCC (Common Command Codes)
* @master: master used to send frames on the bus
@@ -936,6 +976,9 @@ static void i3c_ccc_cmd_init(struct i3c_ccc_cmd *cmd, bool rnw, u8 id,
static int i3c_master_send_ccc_cmd_locked(struct i3c_master_controller *master,
struct i3c_ccc_cmd *cmd)
{
+ unsigned int attempt, max_attempts;
+ int ret;
+
if (!cmd || !master)
return -EINVAL;
@@ -953,7 +996,24 @@ static int i3c_master_send_ccc_cmd_locked(struct i3c_master_controller *master,
!master->ops->supports_ccc_cmd(master, cmd))
return -EOPNOTSUPP;
- return master->ops->send_ccc_cmd(master, cmd);
+ max_attempts = cmd->retries + 1;
+ ret = -EIO;
+ for (attempt = 0; attempt < max_attempts; attempt++) {
+ unsigned int i;
+
+ if (cmd->rnw)
+ for (i = 0; i < cmd->ndests; i++)
+ cmd->dests[i].payload.actual_len = 0;
+
+ cmd->err = I3C_ERROR_UNKNOWN;
+ ret = master->ops->send_ccc_cmd(master, cmd);
+ if (!ret && cmd->rnw)
+ ret = i3c_ccc_validate_payload_len(cmd);
+ if (!ret && cmd->err == I3C_ERROR_UNKNOWN)
+ break;
+ }
+
+ return ret;
}
static struct i2c_dev_desc *
@@ -1291,10 +1351,14 @@ static int i3c_master_getmrl_locked(struct i3c_master_controller *master,
return -ENOMEM;
/*
- * When the device does not have IBI payload GETMRL only returns 2
- * bytes of data.
+ * GETMRL returns 2 bytes (max read length) when the device does not
+ * advertise IBI payload, or 2 or 3 bytes when it does (the optional
+ * third byte is max IBI length). Use optional_bytes to allow either
+ * length when IBI payload is supported.
*/
- if (!(info->bcr & I3C_BCR_IBI_PAYLOAD))
+ if (info->bcr & I3C_BCR_IBI_PAYLOAD)
+ dest.payload.optional_bytes = 1;
+ else
dest.payload.len -= 1;
i3c_ccc_cmd_init(&cmd, true, I3C_CCC_GETMRL, &dest, 1);
@@ -1302,7 +1366,7 @@ static int i3c_master_getmrl_locked(struct i3c_master_controller *master,
if (ret)
goto out;
- switch (dest.payload.len) {
+ switch (dest.payload.actual_len) {
case 3:
info->max_ibi_len = mrl->ibi_len;
fallthrough;
@@ -1337,7 +1401,7 @@ static int i3c_master_getmwl_locked(struct i3c_master_controller *master,
if (ret)
goto out;
- if (dest.payload.len != sizeof(*mwl)) {
+ if (dest.payload.actual_len != sizeof(*mwl)) {
ret = -EIO;
goto out;
}
@@ -1363,6 +1427,8 @@ static int i3c_master_getmxds_locked(struct i3c_master_controller *master,
if (!getmaxds)
return -ENOMEM;
+ dest.payload.optional_bytes = 3;
+
i3c_ccc_cmd_init(&cmd, true, I3C_CCC_GETMXDS, &dest, 1);
ret = i3c_master_send_ccc_cmd_locked(master, &cmd);
if (ret) {
@@ -1371,19 +1437,21 @@ static int i3c_master_getmxds_locked(struct i3c_master_controller *master,
* while expecting shorter length from this CCC command.
*/
dest.payload.len -= 3;
+ dest.payload.optional_bytes = 0;
+ i3c_ccc_cmd_init(&cmd, true, I3C_CCC_GETMXDS, &dest, 1);
ret = i3c_master_send_ccc_cmd_locked(master, &cmd);
if (ret)
goto out;
}
- if (dest.payload.len != 2 && dest.payload.len != 5) {
+ if (dest.payload.actual_len != 2 && dest.payload.actual_len != 5) {
ret = -EIO;
goto out;
}
info->max_read_ds = getmaxds->maxrd;
info->max_write_ds = getmaxds->maxwr;
- if (dest.payload.len == 5)
+ if (dest.payload.actual_len == 5)
info->max_read_turnaround = getmaxds->maxrdturn[0] |
((u32)getmaxds->maxrdturn[1] << 8) |
((u32)getmaxds->maxrdturn[2] << 16);
@@ -1412,7 +1480,7 @@ static int i3c_master_gethdrcap_locked(struct i3c_master_controller *master,
if (ret)
goto out;
- if (dest.payload.len != 1) {
+ if (dest.payload.actual_len != 1) {
ret = -EIO;
goto out;
}
diff --git a/drivers/i3c/master/adi-i3c-master.c b/drivers/i3c/master/adi-i3c-master.c
index 047081c9f064..64735b488726 100644
--- a/drivers/i3c/master/adi-i3c-master.c
+++ b/drivers/i3c/master/adi-i3c-master.c
@@ -360,6 +360,8 @@ static int adi_i3c_master_send_ccc_cmd(struct i3c_master_controller *m,
adi_i3c_master_unqueue_xfer(master, xfer);
cmd->err = adi_i3c_cmd_get_err(&xfer->cmds[0]);
+ if (!xfer->ret && cmd->rnw)
+ cmd->dests[0].payload.actual_len = cmd->dests[0].payload.len;
return xfer->ret;
}
diff --git a/drivers/i3c/master/i3c-master-cdns.c b/drivers/i3c/master/i3c-master-cdns.c
index 5cfec6761494..803c27983852 100644
--- a/drivers/i3c/master/i3c-master-cdns.c
+++ b/drivers/i3c/master/i3c-master-cdns.c
@@ -715,6 +715,8 @@ static int cdns_i3c_master_send_ccc_cmd(struct i3c_master_controller *m,
ret = xfer->ret;
cmd->err = cdns_i3c_cmd_get_err(&xfer->cmds[0]);
+ if (!ret && cmd->rnw)
+ cmd->dests[0].payload.actual_len = cmd->dests[0].payload.len;
cdns_i3c_master_free_xfer(xfer);
return ret;
diff --git a/drivers/i3c/master/mipi-i3c-hci/core.c b/drivers/i3c/master/mipi-i3c-hci/core.c
index b781dbed2165..2b215658e093 100644
--- a/drivers/i3c/master/mipi-i3c-hci/core.c
+++ b/drivers/i3c/master/mipi-i3c-hci/core.c
@@ -326,7 +326,7 @@ static int i3c_hci_send_ccc_cmd(struct i3c_master_controller *m,
goto out;
for (i = prefixed; i < nxfers; i++) {
if (ccc->rnw)
- ccc->dests[i - prefixed].payload.len =
+ ccc->dests[i - prefixed].payload.actual_len =
RESP_DATA_LENGTH(xfer[i].response);
switch (RESP_STATUS(xfer[i].response)) {
case RESP_SUCCESS:
@@ -343,7 +343,8 @@ static int i3c_hci_send_ccc_cmd(struct i3c_master_controller *m,
if (ccc->rnw)
dev_dbg(&hci->master.dev, "got: %*ph",
- ccc->dests[0].payload.len, ccc->dests[0].payload.data);
+ ccc->dests[0].payload.actual_len,
+ ccc->dests[0].payload.data);
out:
hci_free_xfer(xfer, nxfers);
diff --git a/drivers/i3c/master/renesas-i3c.c b/drivers/i3c/master/renesas-i3c.c
index f39c449922ca..fec614700843 100644
--- a/drivers/i3c/master/renesas-i3c.c
+++ b/drivers/i3c/master/renesas-i3c.c
@@ -805,6 +805,8 @@ static int renesas_i3c_send_ccc_cmd(struct i3c_master_controller *m,
ret = xfer->ret;
if (ret)
ccc->err = I3C_ERROR_M2;
+ else if (ccc->rnw)
+ ccc->dests[0].payload.actual_len = cmd->rx_count;
return ret;
}
diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
index e2d99a3ac07d..c92d96e6b4d8 100644
--- a/drivers/i3c/master/svc-i3c-master.c
+++ b/drivers/i3c/master/svc-i3c-master.c
@@ -1706,8 +1706,8 @@ static int svc_i3c_master_send_direct_ccc_cmd(struct svc_i3c_master *master,
svc_i3c_master_dequeue_xfer(master, xfer);
mutex_unlock(&master->lock);
- if (cmd->actual_len != xfer_len)
- ccc->dests[0].payload.len = cmd->actual_len;
+ if (ccc->rnw)
+ ccc->dests[0].payload.actual_len = cmd->actual_len;
ret = xfer->ret;
svc_i3c_master_free_xfer(xfer);
diff --git a/include/linux/i3c/ccc.h b/include/linux/i3c/ccc.h
index d8052949e57e..c8af5db63f7b 100644
--- a/include/linux/i3c/ccc.h
+++ b/include/linux/i3c/ccc.h
@@ -340,16 +340,20 @@ struct i3c_ccc_getxtime {
u8 inaccuracy;
} __packed;
+#define I3C_CCC_RETRIES 1
+
/**
* struct i3c_ccc_cmd_payload - CCC payload
*
* @len: requested payload length
* @actual_len: number of bytes received on a GET CCC (filled by the driver)
+ * @optional_bytes: GET CCCs may return up to this many fewer bytes than @len
* @data: payload data. This buffer must be DMA-able
*/
struct i3c_ccc_cmd_payload {
u16 len;
u16 actual_len;
+ u16 optional_bytes;
void *data;
};
@@ -374,12 +378,15 @@ struct i3c_ccc_cmd_dest {
* @ndests: number of destinations. Should always be one for broadcast commands
* @dests: array of destinations and associated payload for this CCC. Most of
* the time, only one destination is provided
+ * @retries: number of times to retry a failed Direct GET CCC (see
+ * &I3C_CCC_RETRIES)
* @err: I3C error code
*/
struct i3c_ccc_cmd {
u8 rnw;
u8 id;
unsigned int ndests;
+ unsigned int retries;
struct i3c_ccc_cmd_dest *dests;
enum i3c_error_code err;
};
--
2.43.7