[PATCH 06/12] irqchip/stm32-exti: Mark events reserved with RIF configuration check

[Antonio Borneo <antonio.borneo@foss.st.com>]

EXTI events availability depends on Resource Isolation Framework
(RIF) configuration.
RIF grants access to buses with Compartment ID (CID) filtering,
secure and privilege level. It also assigns EXTI events to one or
several processors (CID, Secure, Privilege).

EXTI events used by Linux must be CID-filtered (EnCIDCFGR.CFEN=1)
and statically assigned to CID1 (EnCIDCFR.CID=CID1).
EXTI events not filling these conditions are marked as reserved
and can't be used by Linux.

Signed-off-by: Antonio Borneo <antonio.borneo@foss.st.com>
---
 drivers/irqchip/irq-stm32-exti.c | 40 ++++++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-stm32-exti.c b/drivers/irqchip/irq-stm32-exti.c
index 85a40e07fbc3..68af5fe4764b 100644
--- a/drivers/irqchip/irq-stm32-exti.c
+++ b/drivers/irqchip/irq-stm32-exti.c
@@ -23,9 +23,22 @@
 
 #include <dt-bindings/interrupt-controller/arm-gic.h>
 
-#define IRQS_PER_BANK 32
+#define IRQS_PER_BANK			32
 
-#define HWSPNLCK_TIMEOUT	1000 /* usec */
+#define HWSPNLCK_TIMEOUT		1000 /* usec */
+
+#define EXTI_EnCIDCFGR(n)		(0x180 + (n) * 4)
+#define EXTI_HWCFGR1			0x3f0
+
+/* Register: EXTI_EnCIDCFGR(n) */
+#define EXTI_CIDCFGR_CFEN_MASK		BIT(0)
+#define EXTI_CIDCFGR_CID_MASK		GENMASK(6, 4)
+#define EXTI_CIDCFGR_CID_SHIFT		4
+
+/* Register: EXTI_HWCFGR1 */
+#define EXTI_HWCFGR1_CIDWIDTH_MASK	GENMASK(27, 24)
+
+#define EXTI_CID1			1
 
 struct stm32_exti_bank {
 	u32 imr_ofst;
@@ -910,6 +923,27 @@ static const struct irq_domain_ops stm32_exti_h_domain_ops = {
 	.xlate = irq_domain_xlate_twocell,
 };
 
+static void stm32_exti_check_rif(struct stm32_exti_host_data *host_data)
+{
+	u32 cid, cidcfgr, hwcfgr1;
+	unsigned int bank, i, event;
+
+	/* quit on CID not supported */
+	hwcfgr1 = readl_relaxed(host_data->base + EXTI_HWCFGR1);
+	if ((hwcfgr1 & EXTI_HWCFGR1_CIDWIDTH_MASK) == 0)
+		return;
+
+	for (bank = 0; bank < host_data->drv_data->bank_nr; bank++) {
+		for (i = 0; i < IRQS_PER_BANK; i++) {
+			event = bank * IRQS_PER_BANK + i;
+			cidcfgr = readl_relaxed(host_data->base + EXTI_EnCIDCFGR(event));
+			cid = (cidcfgr & EXTI_CIDCFGR_CID_MASK) >> EXTI_CIDCFGR_CID_SHIFT;
+			if ((cidcfgr & EXTI_CIDCFGR_CFEN_MASK) && cid != EXTI_CID1)
+				host_data->chips_data[bank].event_reserved |= BIT(i);
+		}
+	}
+}
+
 static void stm32_exti_remove_irq(void *data)
 {
 	struct irq_domain *domain = data;
@@ -972,6 +1006,8 @@ static int stm32_exti_probe(struct platform_device *pdev)
 	for (i = 0; i < drv_data->bank_nr; i++)
 		stm32_exti_chip_init(host_data, i, np);
 
+	stm32_exti_check_rif(host_data);
+
 	parent_domain = irq_find_host(of_irq_find_parent(np));
 	if (!parent_domain) {
 		dev_err(dev, "GIC interrupt-parent not found\n");
-- 
2.34.1