[PATCH 2/6] i3c: master: svc: fix wrong data return when IBI happen during start frame

Frank Li
2023-10-16T15:33:00Z

┌─────┐ ┏──┐ ┏──┐ ┏──┐ ┏──┐ ┏──┐ ┏──┐ ┏──┐ ┏──┐ ┌─────
SCL: ┘ └─────┛ └──┛ └──┛ └──┛ └──┛ └──┛ └──┛ └──┛ └──┘
───┐ ┌─────┐ ┌─────┐ ┌───────────┐
SDA: └───────────────────────┘ └─────┘ └─────┘ └─────
xxx╱ ╲╱ ╲╱ ╲╱ ╲╱ ╲
: xxx╲IBI ╱╲ Addr(0x0a) ╱╲ RW ╱╲NACK╱╲ S ╱

In-Band Interrupt (IBI) occurred and IBI work thread may not to be
scheduled. When svc_i3c_master_priv_xfers() initiates the I3C transfer
frame and attempts to send address 0x7e, the target interprets it as an
IBI handler and returns the target address 0x0a.

However, svc_i3c_master_priv_xfers() does not handle this case and proceeds
with other transfers, resulting in incorrect data being returned.

IBIWON check has been added in svc_i3c_master_xfer(). In case this
situation occurs, a failure is now returned to the driver.

Fixes: dd3c52846d59 ("i3c: master: svc: Add Silvaco I3C master driver")
Cc: stable@vger.kernel.org
Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
drivers/i3c/master/svc-i3c-master.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)

diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
index ebdb3ea1af9d..0f57a5f75e39 100644
--- a/drivers/i3c/master/svc-i3c-master.c
+++ b/drivers/i3c/master/svc-i3c-master.c
@@ -1009,6 +1009,9 @@ static int svc_i3c_master_xfer(struct svc_i3c_master *master,
u32 reg;
int ret;

+ /* clean SVC_I3C_MINT_IBIWON w1c bits */
+ writel(SVC_I3C_MINT_IBIWON, master->regs + SVC_I3C_MSTATUS);
+
writel(SVC_I3C_MCTRL_REQUEST_START_ADDR |
xfer_type |
SVC_I3C_MCTRL_IBIRESP_NACK |
@@ -1027,6 +1030,23 @@ static int svc_i3c_master_xfer(struct svc_i3c_master *master,
goto emit_stop;
}

+ /*
+ * According to I3C spec ver 1.1.1, 5.1.2.2.3 Consequence of Controller Starting a Frame
+ * with I3C Target Address.
+ *
+ * The I3C Controller normally should start a Frame, the Address may be arbitrated, and so
+ * the Controller shall monitor to see whether an In-Band Interrupt request, a Controller
+ * Role Request (i.e., Secondary Controller requests to become the Active Controller), or
+ * a Hot-Join Request has been made.
+ *
+ * If missed IBIWON check, the wrong data will be return. When IBIWON happen, return falure
+ * and yeild the above events handler.
+ */
+ if (SVC_I3C_MSTATUS_IBIWON(reg)) {
+ ret = -ENXIO;
+ goto emit_stop;
+ }
+
if (rnw)
ret = svc_i3c_master_read(master, in, xfer_len);
else
--
2.34.1