firmware: imx: scu-irq: support identifying SCU wakeup source from sysfs

Record SCU wakeup interrupt in /sys/power/pm_wakeup_irq
The user can further identify the exact wakeup source by using the
following interface:
cat /sys/firmware/scu_wakeup_source/wakeup_src

The above will print the wake groups and the irqs that could have
contributed to waking up the kernel. For example if ON/OFF button was the
wakeup source:
cat /sys/firmware/scu_wakeup_source/wakeup_src
Wakeup source group = 3, irq = 0x1

The user can refer to the SCFW API documentation to identify all the
wake groups and irqs.
Signed-off-by: Ranjani Vaidyanathan <ranjani.vaidyanathan@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

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

@@ -9,8 +9,10 @@
 #include <dt-bindings/firmware/imx/rsrc.h>
 #include <linux/firmware/imx/ipc.h>
 #include <linux/firmware/imx/sci.h>
+#include <linux/kobject.h>
 #include <linux/mailbox_client.h>
 #include <linux/suspend.h>
+#include <linux/sysfs.h>
 
 #define IMX_SC_IRQ_FUNC_ENABLE	1
 #define IMX_SC_IRQ_FUNC_STATUS	2
@@ -40,6 +42,20 @@ struct imx_sc_msg_irq_enable {
 	u8 enable;
 } __packed;
 
+struct scu_wakeup {
+	u32 mask;
+	u32 wakeup_src;
+	bool valid;
+};
+
+/* Sysfs functions */
+static struct kobject *wakeup_obj;
+static ssize_t wakeup_source_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf);
+static struct kobj_attribute wakeup_source_attr =
+		__ATTR(wakeup_src, 0660, wakeup_source_show, NULL);
+
+static struct scu_wakeup scu_irq_wakeup[IMX_SC_IRQ_NUM_GROUP];
+
 static struct imx_sc_ipc *imx_sc_irq_ipc_handle;
 static struct work_struct imx_sc_irq_work;
 static BLOCKING_NOTIFIER_HEAD(imx_scu_irq_notifier_chain);
@@ -71,6 +87,11 @@ static void imx_scu_irq_work_handler(struct work_struct *work)
 	u8 i;
 
 	for (i = 0; i < IMX_SC_IRQ_NUM_GROUP; i++) {
+		if (scu_irq_wakeup[i].mask) {
+			scu_irq_wakeup[i].valid = false;
+			scu_irq_wakeup[i].wakeup_src = 0;
+		}
+
 		ret = imx_scu_irq_get_status(i, &irq_status);
 		if (ret) {
 			pr_err("get irq group %d status failed, ret %d\n",
@@ -80,6 +101,12 @@ static void imx_scu_irq_work_handler(struct work_struct *work)
 
 		if (!irq_status)
 			continue;
+		if (scu_irq_wakeup[i].mask & irq_status) {
+			scu_irq_wakeup[i].valid = true;
+			scu_irq_wakeup[i].wakeup_src = irq_status & scu_irq_wakeup[i].mask;
+		} else {
+			scu_irq_wakeup[i].wakeup_src = irq_status;
+		}
 
 		pm_system_wakeup();
 		imx_scu_irq_notifier_call_chain(irq_status, &i);
@@ -135,6 +162,11 @@ int imx_scu_irq_group_enable(u8 group, u32 mask, u8 enable)
 		pr_err("enable irq failed, group %d, mask %d, ret %d\n",
 			group, mask, ret);
 
+	if (enable)
+		scu_irq_wakeup[group].mask |= mask;
+	else
+		scu_irq_wakeup[group].mask &= ~mask;
+
 	return ret;
 }
 EXPORT_SYMBOL(imx_scu_irq_group_enable);
@@ -144,6 +176,25 @@ static void imx_scu_irq_callback(struct mbox_client *c, void *msg)
 	schedule_work(&imx_sc_irq_work);
 }
 
+static ssize_t wakeup_source_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
+{
+	int i;
+
+	for (i = 0; i < IMX_SC_IRQ_NUM_GROUP; i++) {
+		if (!scu_irq_wakeup[i].wakeup_src)
+			continue;
+
+		if (scu_irq_wakeup[i].valid)
+			sprintf(buf, "Wakeup source group = %d, irq = 0x%x\n",
+				i, scu_irq_wakeup[i].wakeup_src);
+		else
+			sprintf(buf, "Spurious SCU wakeup, group = %d, irq = 0x%x\n",
+				i, scu_irq_wakeup[i].wakeup_src);
+	}
+
+	return strlen(buf);
+}
+
 int imx_scu_enable_general_irq_channel(struct device *dev)
 {
 	struct of_phandle_args spec;
@@ -183,6 +234,25 @@ int imx_scu_enable_general_irq_channel(struct device *dev)
 
 	mu_resource_id = IMX_SC_R_MU_0A + i;
 
+	/* Create directory under /sysfs/firmware */
+	wakeup_obj = kobject_create_and_add("scu_wakeup_source", firmware_kobj);
+	if (!wakeup_obj) {
+		ret = -ENOMEM;
+		goto free_ch;
+	}
+
+	ret = sysfs_create_file(wakeup_obj, &wakeup_source_attr.attr);
+	if (ret) {
+		dev_err(dev, "Cannot create wakeup source src file......\n");
+		kobject_put(wakeup_obj);
+		goto free_ch;
+	}
+
+	return 0;
+
+free_ch:
+	mbox_free_channel(ch);
+
 	return ret;
 }
 EXPORT_SYMBOL(imx_scu_enable_general_irq_channel);