[PATCH v6 2/5] pinctrl: mediatek: free EINT resources on unbind

[Justin Yeh <justin.yeh@mediatek.com>]

mtk_eint_do_init() creates an IRQ domain, populates it with a mapping for
every EINT line and installs a chained handler on the parent interrupt,
but none of these are ever released. This was harmless while the drivers
were built-in, but now that they can be built as modules and
unbound/rmmod'd it leaves behind a dangling IRQ domain, interrupt mappings
whose chip data points at freed memory, and a chained handler that keeps
firing into that freed data.

The plain allocations in mtk_eint_do_init() already use the device-managed
devm_*() helpers, so tear the remaining resources down the same way:
register a devm action that detaches the chained handler, disposes of the
per-line mappings and removes the IRQ domain. This mirrors the
device-managed lifecycle adopted for the GPIO chip and keeps the whole
EINT setup self-cleaning on unbind.

Fixes: e46df235b4e6 ("pinctrl: mediatek: refactor EINT related code for all MediaTek pinctrl can fit")
Signed-off-by: Justin Yeh <justin.yeh@mediatek.com>
---
 drivers/pinctrl/mediatek/mtk-eint.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/pinctrl/mediatek/mtk-eint.c b/drivers/pinctrl/mediatek/mtk-eint.c
index 47ac92ea98c2..7cd4c4a9fc77 100644
--- a/drivers/pinctrl/mediatek/mtk-eint.c
+++ b/drivers/pinctrl/mediatek/mtk-eint.c
@@ -12,6 +12,7 @@
  */
 
 #include <linux/delay.h>
+#include <linux/device.h>
 #include <linux/err.h>
 #include <linux/gpio/driver.h>
 #include <linux/io.h>
@@ -509,6 +510,24 @@ int mtk_eint_find_irq(struct mtk_eint *eint, unsigned long eint_n)
 }
 EXPORT_SYMBOL_GPL(mtk_eint_find_irq);
 
+static void mtk_eint_teardown(void *data)
+{
+	struct mtk_eint *eint = data;
+	unsigned int i, virq;
+
+	/* Detach the demux handler so it can no longer reference freed data. */
+	irq_set_chained_handler_and_data(eint->irq, NULL, NULL);
+
+	/* Dispose of all child mappings before the domain is removed. */
+	for (i = 0; i < eint->hw->ap_num; i++) {
+		virq = irq_find_mapping(eint->domain, i);
+		if (virq)
+			irq_dispose_mapping(virq);
+	}
+
+	irq_domain_remove(eint->domain);
+}
+
 int mtk_eint_do_init(struct mtk_eint *eint, struct mtk_eint_pin *eint_pin)
 {
 	unsigned int size, i, port, virq, inst = 0;
@@ -601,7 +620,7 @@ int mtk_eint_do_init(struct mtk_eint *eint, struct mtk_eint_pin *eint_pin)
 	irq_set_chained_handler_and_data(eint->irq, mtk_eint_irq_handler,
 					 eint);
 
-	return 0;
+	return devm_add_action_or_reset(eint->dev, mtk_eint_teardown, eint);
 
 err_eint:
 	for (i = 0; i < eint->nbase; i++) {
-- 
2.45.2