i3c: master: svc: Fix npcm845 invalid slvstart event

I3C HW may generate an invalid SlvStart event when emitting a STOP.
If it is a true SlvStart, the MSTATUS state is SLVREQ. Check the
MSTATUS state to ignore the false event.

Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Stanley Chu <yschu@nuvoton.com>
Link: https://lore.kernel.org/r/20250306075429.2265183-5-yschu@nuvoton.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Author: stanleychuys

drivers/i3c/master/svc-i3c-master.c

@@ -58,6 +58,7 @@
 #define SVC_I3C_MSTATUS      0x088
 #define   SVC_I3C_MSTATUS_STATE(x) FIELD_GET(GENMASK(2, 0), (x))
 #define   SVC_I3C_MSTATUS_STATE_DAA(x) (SVC_I3C_MSTATUS_STATE(x) == 5)
+#define   SVC_I3C_MSTATUS_STATE_SLVREQ(x) (SVC_I3C_MSTATUS_STATE(x) == 1)
 #define   SVC_I3C_MSTATUS_STATE_IDLE(x) (SVC_I3C_MSTATUS_STATE(x) == 0)
 #define   SVC_I3C_MSTATUS_BETWEEN(x) FIELD_GET(BIT(4), (x))
 #define   SVC_I3C_MSTATUS_NACKED(x) FIELD_GET(BIT(5), (x))
@@ -143,6 +144,12 @@
  * Fill the FIFO in advance to prevent FIFO from becoming empty.
  */
 #define SVC_I3C_QUIRK_FIFO_EMPTY	BIT(0)
+/*
+ * SVC_I3C_QUIRK_FLASE_SLVSTART:
+ * I3C HW may generate an invalid SlvStart event when emitting a STOP.
+ * If it is a true SlvStart, the MSTATUS state is SLVREQ.
+ */
+#define SVC_I3C_QUIRK_FALSE_SLVSTART	BIT(1)
 
 struct svc_i3c_cmd {
 	u8 addr;
@@ -586,6 +593,11 @@ static irqreturn_t svc_i3c_master_irq_handler(int irq, void *dev_id)
 	/* Clear the interrupt status */
 	writel(SVC_I3C_MINT_SLVSTART, master->regs + SVC_I3C_MSTATUS);
 
+	/* Ignore the false event */
+	if (svc_has_quirk(master, SVC_I3C_QUIRK_FALSE_SLVSTART) &&
+	    !SVC_I3C_MSTATUS_STATE_SLVREQ(active))
+		return IRQ_HANDLED;
+
 	svc_i3c_master_disable_interrupts(master);
 
 	/* Handle the interrupt in a non atomic context */
@@ -2020,7 +2032,8 @@ static const struct dev_pm_ops svc_i3c_pm_ops = {
 };
 
 static const struct svc_i3c_drvdata npcm845_drvdata = {
-	.quirks = SVC_I3C_QUIRK_FIFO_EMPTY,
+	.quirks = SVC_I3C_QUIRK_FIFO_EMPTY |
+		SVC_I3C_QUIRK_FALSE_SLVSTART,
 };
 
 static const struct svc_i3c_drvdata svc_default_drvdata = {};