[PATCH v2] pinctrl: qcom: msm: mark certain pins as invalid for interrupts

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>

On some platforms, the UFS-reset pin has no interrupt logic in TLMM but
is nevertheless registered as a GPIO in the kernel. This enables the
user-space to trigger a BUG() in the pinctrl-msm driver by running, for
example: `gpiomon -c 0 113` on RB2.

The exact culprit is requesting pins whose intr_detection_width setting
is not 1 or 2 for interrupts. This hits a BUG() in
msm_gpio_irq_set_type(). Potentially crashing the kernel due to an
invalid request from user-space is not optimal, so let's go through the
pins and mark those that would fail the check as invalid for the irq chip
as we should not even register them as available irqs.

This function can be extended if we determine that there are more
corner-cases like this.

Fixes: f365be092572 ("pinctrl: Add Qualcomm TLMM driver")
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Bjorn Andersson <andersson@xxxxxxxxxx>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
---
Changes in v2:
- expand the commit message, describing the underlying code issue in
  detail
- added a newline for better readability

 drivers/pinctrl/qcom/pinctrl-msm.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/pinctrl/qcom/pinctrl-msm.c b/drivers/pinctrl/qcom/pinctrl-msm.c
index f012ea88aa22c..1ff84e8c176d4 100644
--- a/drivers/pinctrl/qcom/pinctrl-msm.c
+++ b/drivers/pinctrl/qcom/pinctrl-msm.c
@@ -1038,6 +1038,25 @@ static bool msm_gpio_needs_dual_edge_parent_workaround(struct irq_data *d,
 	       test_bit(d->hwirq, pctrl->skip_wake_irqs);
 }
 
+static void msm_gpio_irq_init_valid_mask(struct gpio_chip *gc,
+					 unsigned long *valid_mask,
+					 unsigned int ngpios)
+{
+	struct msm_pinctrl *pctrl = gpiochip_get_data(gc);
+	const struct msm_pingroup *g;
+	int i;
+
+	bitmap_fill(valid_mask, ngpios);
+
+	for (i = 0; i < ngpios; i++) {
+		g = &pctrl->soc->groups[i];
+
+		if (g->intr_detection_width != 1 &&
+		    g->intr_detection_width != 2)
+			clear_bit(i, valid_mask);
+	}
+}
+
 static int msm_gpio_irq_set_type(struct irq_data *d, unsigned int type)
 {
 	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
@@ -1441,6 +1460,7 @@ static int msm_gpio_init(struct msm_pinctrl *pctrl)
 	girq->default_type = IRQ_TYPE_NONE;
 	girq->handler = handle_bad_irq;
 	girq->parents[0] = pctrl->irq;
+	girq->init_valid_mask = msm_gpio_irq_init_valid_mask;
 
 	ret = gpiochip_add_data(&pctrl->chip, pctrl);
 	if (ret) {
-- 
2.48.1