[PATCH v2] firmware: imx: scu-irq: drop wakeup_src sysfs file, log via dev_dbg()

[Stepan Ionichev <sozdayvek@gmail.com>]

wakeup_source_show() walks all IMX_SC_IRQ_NUM_GROUP groups and
rewrites buf from offset 0 each iteration, so userspace reading
/sys/firmware/scu_wakeup_source/wakeup_src only ever sees the last
group reported, and the trailing strlen(buf) reports only that
line length. sprintf() is also unbounded against the sysfs
PAGE_SIZE buffer.

The attribute is not documented under Documentation/ABI/ and a code
search across GitHub and Debian found no out-of-tree consumers.
Peng Fan (NXP) confirmed it is safe to drop.

Remove the attribute, the supporting kobject and the per-group
valid/wakeup_src state used only to feed it. Log the same wakeup
information via dev_dbg() from imx_scu_irq_work_handler() so it
can be enabled dynamically when needed.

Fixes: c081197a33a2 ("firmware: imx: scu-irq: support identifying SCU wakeup source from sysfs")
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/all/2026051656-corral-edgy-290c@gregkh/
Signed-off-by: Stepan Ionichev <sozdayvek@gmail.com>
---
v2:
- Drop the sysfs file entirely instead of patching it (Greg)
- Log wakeup info via dev_dbg() in the IRQ work handler (Greg)
- Peng Fan (NXP) confirmed no out-of-tree consumers

v1: https://lore.kernel.org/all/20260515175002.34853-1-sozdayvek@gmail.com/

 drivers/firmware/imx/imx-scu-irq.c | 84 ++++++------------------------
 1 file changed, 16 insertions(+), 68 deletions(-)

diff --git a/drivers/firmware/imx/imx-scu-irq.c b/drivers/firmware/imx/imx-scu-irq.c
index a68d38f89..5969460ba 100644
--- a/drivers/firmware/imx/imx-scu-irq.c
+++ b/drivers/firmware/imx/imx-scu-irq.c
@@ -9,11 +9,9 @@
 #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/of.h>
 #include <linux/suspend.h>
-#include <linux/sysfs.h>
 
 #define IMX_SC_IRQ_FUNC_ENABLE	1
 #define IMX_SC_IRQ_FUNC_STATUS	2
@@ -43,19 +41,8 @@ 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 u32 scu_irq_wakeup_mask[IMX_SC_IRQ_NUM_GROUP];
+static struct device *imx_sc_irq_dev;
 
 static struct imx_sc_ipc *imx_sc_irq_ipc_handle;
 static struct work_struct imx_sc_irq_work;
@@ -88,11 +75,6 @@ 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",
@@ -102,12 +84,15 @@ 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;
-		}
+
+		if (scu_irq_wakeup_mask[i] & irq_status)
+			dev_dbg(imx_sc_irq_dev,
+				"Wakeup source group = %d, irq = 0x%x\n",
+				i, irq_status & scu_irq_wakeup_mask[i]);
+		else
+			dev_dbg(imx_sc_irq_dev,
+				"Spurious SCU wakeup, group = %d, irq = 0x%x\n",
+				i, irq_status);
 
 		pm_system_wakeup();
 		imx_scu_irq_notifier_call_chain(irq_status, &i);
@@ -164,9 +149,9 @@ int imx_scu_irq_group_enable(u8 group, u32 mask, u8 enable)
 			group, mask, ret);
 
 	if (enable)
-		scu_irq_wakeup[group].mask |= mask;
+		scu_irq_wakeup_mask[group] |= mask;
 	else
-		scu_irq_wakeup[group].mask &= ~mask;
+		scu_irq_wakeup_mask[group] &= ~mask;
 
 	return ret;
 }
@@ -177,25 +162,6 @@ 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;
@@ -233,29 +199,11 @@ int imx_scu_enable_general_irq_channel(struct device *dev)
 	if (IS_ERR(ch)) {
 		ret = PTR_ERR(ch);
 		dev_err(dev, "failed to request mbox chan gip3, ret %d\n", ret);
-		goto free_cl;
-	}
-
-	/* Create directory under /sysfs/firmware */
-	wakeup_obj = kobject_create_and_add("scu_wakeup_source", firmware_kobj);
-	if (!wakeup_obj) {
-		ret = -ENOMEM;
-		goto free_ch;
+		devm_kfree(dev, cl);
+		return ret;
 	}
 
-	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;
-	}
+	imx_sc_irq_dev = dev;
 
 	return 0;
-
-free_ch:
-	mbox_free_channel(ch);
-free_cl:
-	devm_kfree(dev, cl);
-
-	return ret;
 }
-- 
2.43.0