[PATCH 1/4] mailbox: zynqmp: support smc calls to TF-A

[Tanmay Shah]

Use SMC calls to TF-A to operate IPI for execution level below 3. For
EL3 use hardcode IPI registers as TF-A isn't available in EL3.
Hence, in EL3 remote and local IPI ids retrieved using xlnx,ipi-id
property are unused.

Signed-off-by: Tanmay Shah <tanmay.shah at amd.com>
---
 drivers/mailbox/zynqmp-ipi.c | 88 +++++++++++++++++++++++++++++++++++-
 1 file changed, 86 insertions(+), 2 deletions(-)

diff --git a/drivers/mailbox/zynqmp-ipi.c b/drivers/mailbox/zynqmp-ipi.c
index 3e4ec47389..acd0b287db 100644
--- a/drivers/mailbox/zynqmp-ipi.c
+++ b/drivers/mailbox/zynqmp-ipi.c
@@ -8,9 +8,12 @@
 #include <common.h>
 #include <log.h>
 #include <asm/io.h>
+#include <asm/system.h>
 #include <dm.h>
 #include <mailbox-uclass.h>
 #include <dm/device_compat.h>
+#include <dm/of_access.h>
+#include <linux/arm-smccc.h>
 #include <linux/ioport.h>
 #include <linux/io.h>
 #include <wait_bit.h>
@@ -21,6 +24,43 @@
 #define IPI_BIT_MASK_PMU0     0x10000
 #define IPI_INT_REG_BASE_APU  0xFF300000
 
+/* IPI agent ID any */
+#define IPI_ID_ANY 0xFFUL
+
+/* indicate if ZynqMP IPI mailbox driver uses SMC calls or HVC calls */
+#define USE_SMC 0
+
+/* Default IPI SMC function IDs */
+#define SMC_IPI_MAILBOX_OPEN		0x82001000U
+#define SMC_IPI_MAILBOX_RELEASE		0x82001001U
+#define SMC_IPI_MAILBOX_STATUS_ENQUIRY	0x82001002U
+#define SMC_IPI_MAILBOX_NOTIFY		0x82001003U
+#define SMC_IPI_MAILBOX_ACK		0x82001004U
+#define SMC_IPI_MAILBOX_ENABLE_IRQ	0x82001005U
+#define SMC_IPI_MAILBOX_DISABLE_IRQ	0x82001006U
+
+/* IPI SMC Macros */
+
+/*
+ * Flag to indicate if notification interrupt
+ * to be disabled.
+ */
+#define IPI_SMC_ENQUIRY_DIRQ_MASK	BIT(0)
+
+/*
+ * Flag to indicate if notification interrupt
+ * to be enabled.
+ */
+#define IPI_SMC_ACK_EIRQ_MASK		BIT(0)
+
+/* IPI mailbox status */
+#define IPI_MB_STATUS_IDLE		0
+#define IPI_MB_STATUS_SEND_PENDING	1
+#define IPI_MB_STATUS_RECV_PENDING	2
+
+#define IPI_MB_CHNL_TX	0 /* IPI mailbox TX channel */
+#define IPI_MB_CHNL_RX	1 /* IPI mailbox RX channel */
+
 struct ipi_int_regs {
 	u32 trig; /* 0x0  */
 	u32 obs;  /* 0x4  */
@@ -39,8 +79,23 @@ struct zynqmp_ipi {
 	void __iomem *local_res_regs;
 	void __iomem *remote_req_regs;
 	void __iomem *remote_res_regs;
+	u32 remote_id;
+	u32 local_id;
 };
 
+static int zynqmp_ipi_fw_call(struct zynqmp_ipi *ipi_mbox,
+			      unsigned long a0, unsigned long a3)
+{
+	struct arm_smccc_res res = {0};
+	unsigned long a1, a2;
+
+	a1 = ipi_mbox->local_id;
+	a2 = ipi_mbox->remote_id;
+	arm_smccc_smc(a0, a1, a2, a3, 0, 0, 0, 0, &res);
+
+	return (int)res.a0;
+}
+
 static int zynqmp_ipi_send(struct mbox_chan *chan, const void *data)
 {
 	const struct zynqmp_ipi_msg *msg = (struct zynqmp_ipi_msg *)data;
@@ -51,6 +106,15 @@ static int zynqmp_ipi_send(struct mbox_chan *chan, const void *data)
 	for (size_t i = 0; i < msg->len; i++)
 		writel(msg->buf[i], &mbx[i]);
 
+	/* Use SMC calls for Exception Level less than 3 where TF-A is available */
+	if (!IS_ENABLED(CONFIG_SPL_BUILD) && current_el() < 3) {
+		ret = zynqmp_ipi_fw_call(zynqmp, SMC_IPI_MAILBOX_NOTIFY, 0);
+
+		debug("%s, send %ld bytes\n", __func__, msg->len);
+
+		return ret;
+	}
+
 	/* Write trigger interrupt */
 	writel(IPI_BIT_MASK_PMU0, &ipi_int_apu->trig);
 
@@ -67,16 +131,23 @@ static int zynqmp_ipi_recv(struct mbox_chan *chan, void *data)
 	struct zynqmp_ipi_msg *msg = (struct zynqmp_ipi_msg *)data;
 	struct zynqmp_ipi *zynqmp = dev_get_priv(chan->dev);
 	u32 *mbx = (u32 *)zynqmp->local_res_regs;
+	int ret = 0;
 
 	/*
 	 * PMU Firmware does not trigger IPI interrupt for API call responses so
-	 * there is no need to check ISR flags
+	 * there is no need to check ISR flags for EL3.
 	 */
 	for (size_t i = 0; i < msg->len; i++)
 		msg->buf[i] = readl(&mbx[i]);
 
+	/* Ack to remote if EL is not 3 */
+	if (!IS_ENABLED(CONFIG_SPL_BUILD) && current_el() < 3) {
+		ret = zynqmp_ipi_fw_call(zynqmp, SMC_IPI_MAILBOX_ACK,
+					 IPI_SMC_ACK_EIRQ_MASK);
+	}
+
 	debug("%s, recv %ld bytes\n", __func__, msg->len);
-	return 0;
+	return ret;
 };
 
 static int zynqmp_ipi_probe(struct udevice *dev)
@@ -84,6 +155,7 @@ static int zynqmp_ipi_probe(struct udevice *dev)
 	struct zynqmp_ipi *zynqmp = dev_get_priv(dev);
 	struct resource res;
 	ofnode node;
+	int ret;
 
 	debug("%s(dev=%p)\n", __func__, dev);
 
@@ -91,6 +163,18 @@ static int zynqmp_ipi_probe(struct udevice *dev)
 	/* Note IPI mailbox node needs to be the first one in DT */
 	node = ofnode_first_subnode(dev_ofnode(dev));
 
+	ret = dev_read_u32(dev, "xlnx,ipi-id", &zynqmp->local_id);
+	if (ret) {
+		dev_err(dev, "can't get local ipi id\n");
+		return ret;
+	}
+
+	ret = ofnode_read_u32(node, "xlnx,ipi-id", &zynqmp->remote_id);
+	if (ret) {
+		dev_err(dev, "can't get remote ipi id\n");
+		return ret;
+	}
+
 	if (ofnode_read_resource_byname(node, "local_request_region", &res)) {
 		dev_err(dev, "No reg property for local_request_region\n");
 		return -EINVAL;
-- 
2.25.1