bus: rifsc: fix RIF configuration check for peripherals

[ Upstream commit d5ce3b4 ]

Peripheral holding CID0 cannot be accessed, remove this completely
incorrect check. While there, fix  and simplify the semaphore checking
that should be performed when the CID filtering is enabled.

Fixes: a182084 ("bus: rifsc: introduce RIFSC firewall controller driver")
Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>
Link: https://lore.kernel.org/r/20260129-fix_cid_check_rifsc-v1-1-ef280ccf764d@foss.st.com
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: GseoC

drivers/bus/stm32_rifsc.c

@@ -126,54 +126,38 @@ static int stm32_rifsc_grant_access(struct stm32_firewall_controller *ctrl, u32
 	sec_reg_value = readl(rifsc_controller->mmio + RIFSC_RISC_SECCFGR0 + 0x4 * reg_id);
 	cid_reg_value = readl(rifsc_controller->mmio + RIFSC_RISC_PER0_CIDCFGR + 0x8 * firewall_id);
 
-	/* First check conditions for semaphore mode, which doesn't take into account static CID. */
-	if ((cid_reg_value & CIDCFGR_SEMEN) && (cid_reg_value & CIDCFGR_CFEN)) {
-		if (cid_reg_value & BIT(RIF_CID1 + SEMWL_SHIFT)) {
-			/* Static CID is irrelevant if semaphore mode */
-			goto skip_cid_check;
-		} else {
-			dev_dbg(rifsc_controller->dev,
-				"Invalid bus semaphore configuration: index %d\n", firewall_id);
-			return -EACCES;
-		}
-	}
-
-	/*
-	 * Skip CID check if CID filtering isn't enabled or filtering is enabled on CID0, which
-	 * corresponds to whatever CID.
-	 */
-	if (!(cid_reg_value & CIDCFGR_CFEN) ||
-	    FIELD_GET(RIFSC_RISC_SCID_MASK, cid_reg_value) == RIF_CID0)
-		goto skip_cid_check;
-
-	/* Coherency check with the CID configuration */
-	if (FIELD_GET(RIFSC_RISC_SCID_MASK, cid_reg_value) != RIF_CID1) {
-		dev_dbg(rifsc_controller->dev, "Invalid CID configuration for peripheral: %d\n",
-			firewall_id);
-		return -EACCES;
-	}
-
-skip_cid_check:
 	/* Check security configuration */
 	if (sec_reg_value & BIT(reg_offset)) {
 		dev_dbg(rifsc_controller->dev,
 			"Invalid security configuration for peripheral: %d\n", firewall_id);
 		return -EACCES;
 	}
 
-	/*
-	 * If the peripheral is in semaphore mode, take the semaphore so that
-	 * the CID1 has the ownership.
-	 */
-	if ((cid_reg_value & CIDCFGR_SEMEN) && (cid_reg_value & CIDCFGR_CFEN)) {
+	/* Skip CID check if CID filtering isn't enabled */
+	if (!(cid_reg_value & CIDCFGR_CFEN))
+		goto skip_cid_check;
+
+	/* First check conditions for semaphore mode, which doesn't take into account static CID. */
+	if (cid_reg_value & CIDCFGR_SEMEN) {
+		if (!(cid_reg_value & BIT(RIF_CID1 + SEMWL_SHIFT))) {
+			dev_dbg(rifsc_controller->dev,
+				"Invalid bus semaphore configuration: index %d\n", firewall_id);
+			return -EACCES;
+		}
+
 		rc = stm32_rif_acquire_semaphore(rifsc_controller, firewall_id);
 		if (rc) {
-			dev_err(rifsc_controller->dev,
+			dev_dbg(rifsc_controller->dev,
 				"Couldn't acquire semaphore for peripheral: %d\n", firewall_id);
 			return rc;
 		}
+	} else if (FIELD_GET(RIFSC_RISC_SCID_MASK, cid_reg_value) != RIF_CID1) {
+		dev_dbg(rifsc_controller->dev, "Invalid CID configuration for peripheral: %d\n",
+			firewall_id);
+		return -EACCES;
 	}
 
+skip_cid_check:
 	return 0;
 }