firmware: imx: enable imx scu general irq function

The System Controller Firmware (SCFW) controls RTC, thermal
and WDOG etc., these resources' interrupt function are managed
by SCU. When any IRQ pending, SCU will notify Linux via MU general
interrupt channel #3, and Linux kernel needs to call SCU APIs
to get IRQ status and notify each module to handle the interrupt.

Since there is no data transmission for SCU IRQ notification, so
doorbell mode is used for this MU channel, and SCU driver will
use notifier mechanism to broadcast to every module which registers
the SCU block notifier.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

drivers/firmware/imx/Makefile

@@ -1,3 +1,3 @@
 # SPDX-License-Identifier: GPL-2.0
-obj-$(CONFIG_IMX_SCU)		+= imx-scu.o misc.o
+obj-$(CONFIG_IMX_SCU)		+= imx-scu.o misc.o imx-scu-irq.o
 obj-$(CONFIG_IMX_SCU_PD)	+= scu-pd.o

drivers/firmware/imx/imx-scu-irq.c

@@ -0,0 +1,168 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2019 NXP
+ *
+ * Implementation of the SCU IRQ functions using MU.
+ *
+ */
+
+#include <dt-bindings/firmware/imx/rsrc.h>
+#include <linux/firmware/imx/ipc.h>
+#include <linux/mailbox_client.h>
+
+#define IMX_SC_IRQ_FUNC_ENABLE	1
+#define IMX_SC_IRQ_FUNC_STATUS	2
+#define IMX_SC_IRQ_NUM_GROUP	4
+
+static u32 mu_resource_id;
+
+struct imx_sc_msg_irq_get_status {
+	struct imx_sc_rpc_msg hdr;
+	union {
+		struct {
+			u16 resource;
+			u8 group;
+			u8 reserved;
+		} __packed req;
+		struct {
+			u32 status;
+		} resp;
+	} data;
+};
+
+struct imx_sc_msg_irq_enable {
+	struct imx_sc_rpc_msg hdr;
+	u32 mask;
+	u16 resource;
+	u8 group;
+	u8 enable;
+} __packed;
+
+static struct imx_sc_ipc *imx_sc_irq_ipc_handle;
+static struct work_struct imx_sc_irq_work;
+static ATOMIC_NOTIFIER_HEAD(imx_scu_irq_notifier_chain);
+
+int imx_scu_irq_register_notifier(struct notifier_block *nb)
+{
+	return atomic_notifier_chain_register(
+		&imx_scu_irq_notifier_chain, nb);
+}
+EXPORT_SYMBOL(imx_scu_irq_register_notifier);
+
+int imx_scu_irq_unregister_notifier(struct notifier_block *nb)
+{
+	return atomic_notifier_chain_unregister(
+		&imx_scu_irq_notifier_chain, nb);
+}
+EXPORT_SYMBOL(imx_scu_irq_unregister_notifier);
+
+static int imx_scu_irq_notifier_call_chain(unsigned long status, u8 *group)
+{
+	return atomic_notifier_call_chain(&imx_scu_irq_notifier_chain,
+		status, (void *)group);
+}
+
+static void imx_scu_irq_work_handler(struct work_struct *work)
+{
+	struct imx_sc_msg_irq_get_status msg;
+	struct imx_sc_rpc_msg *hdr = &msg.hdr;
+	u32 irq_status;
+	int ret;
+	u8 i;
+
+	for (i = 0; i < IMX_SC_IRQ_NUM_GROUP; i++) {
+		hdr->ver = IMX_SC_RPC_VERSION;
+		hdr->svc = IMX_SC_RPC_SVC_IRQ;
+		hdr->func = IMX_SC_IRQ_FUNC_STATUS;
+		hdr->size = 2;
+
+		msg.data.req.resource = mu_resource_id;
+		msg.data.req.group = i;
+
+		ret = imx_scu_call_rpc(imx_sc_irq_ipc_handle, &msg, true);
+		if (ret) {
+			pr_err("get irq group %d status failed, ret %d\n",
+			       i, ret);
+			return;
+		}
+
+		irq_status = msg.data.resp.status;
+		if (!irq_status)
+			continue;
+
+		imx_scu_irq_notifier_call_chain(irq_status, &i);
+	}
+}
+
+int imx_scu_irq_group_enable(u8 group, u32 mask, u8 enable)
+{
+	struct imx_sc_msg_irq_enable msg;
+	struct imx_sc_rpc_msg *hdr = &msg.hdr;
+	int ret;
+
+	hdr->ver = IMX_SC_RPC_VERSION;
+	hdr->svc = IMX_SC_RPC_SVC_IRQ;
+	hdr->func = IMX_SC_IRQ_FUNC_ENABLE;
+	hdr->size = 3;
+
+	msg.resource = mu_resource_id;
+	msg.group = group;
+	msg.mask = mask;
+	msg.enable = enable;
+
+	ret = imx_scu_call_rpc(imx_sc_irq_ipc_handle, &msg, true);
+	if (ret)
+		pr_err("enable irq failed, group %d, mask %d, ret %d\n",
+			group, mask, ret);
+
+	return ret;
+}
+EXPORT_SYMBOL(imx_scu_irq_group_enable);
+
+static void imx_scu_irq_callback(struct mbox_client *c, void *msg)
+{
+	schedule_work(&imx_sc_irq_work);
+}
+
+int imx_scu_enable_general_irq_channel(struct device *dev)
+{
+	struct of_phandle_args spec;
+	struct mbox_client *cl;
+	struct mbox_chan *ch;
+	int ret = 0, i = 0;
+
+	ret = imx_scu_get_handle(&imx_sc_irq_ipc_handle);
+	if (ret)
+		return ret;
+
+	cl = devm_kzalloc(dev, sizeof(*cl), GFP_KERNEL);
+	if (!cl)
+		return -ENOMEM;
+
+	cl->dev = dev;
+	cl->rx_callback = imx_scu_irq_callback;
+
+	/* SCU general IRQ uses general interrupt channel 3 */
+	ch = mbox_request_channel_byname(cl, "gip3");
+	if (IS_ERR(ch)) {
+		ret = PTR_ERR(ch);
+		dev_err(dev, "failed to request mbox chan gip3, ret %d\n", ret);
+		devm_kfree(dev, cl);
+		return ret;
+	}
+
+	INIT_WORK(&imx_sc_irq_work, imx_scu_irq_work_handler);
+
+	if (!of_parse_phandle_with_args(dev->of_node, "mboxes",
+				       "#mbox-cells", 0, &spec))
+		i = of_alias_get_id(spec.np, "mu");
+
+	/* use mu1 as general mu irq channel if failed */
+	if (i < 0)
+		i = 1;
+
+	mu_resource_id = IMX_SC_R_MU_0A + i;
+
+	return ret;
+}
+EXPORT_SYMBOL(imx_scu_enable_general_irq_channel);

drivers/firmware/imx/imx-scu.c

@@ -10,6 +10,7 @@
 #include <linux/err.h>
 #include <linux/firmware/imx/types.h>
 #include <linux/firmware/imx/ipc.h>
+#include <linux/firmware/imx/sci.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <linux/kernel.h>
@@ -246,6 +247,11 @@ static int imx_scu_probe(struct platform_device *pdev)
 
 	imx_sc_ipc_handle = sc_ipc;
 
+	ret = imx_scu_enable_general_irq_channel(dev);
+	if (ret)
+		dev_warn(dev,
+			"failed to enable general irq channel: %d\n", ret);
+
 	dev_info(dev, "NXP i.MX SCU Initialized\n");
 
 	return devm_of_platform_populate(dev);

include/linux/firmware/imx/sci.h

@@ -15,4 +15,9 @@
 
 #include <linux/firmware/imx/svc/misc.h>
 #include <linux/firmware/imx/svc/pm.h>
+
+int imx_scu_enable_general_irq_channel(struct device *dev);
+int imx_scu_irq_register_notifier(struct notifier_block *nb);
+int imx_scu_irq_unregister_notifier(struct notifier_block *nb);
+int imx_scu_irq_group_enable(u8 group, u32 mask, u8 enable);
 #endif /* _SC_SCI_H */