[PATCH v2] i2c: exynos5: Init data before registering interrupt handler

[Jesper Nilsson]

devm_request_irq() is called before we initialize the "variant"
member variable from of_device_get_match_data(), so if an interrupt
is triggered inbetween, we can end up following a NULL pointer
in the interrupt handler.

This problem was exposed when the I2C controller in question was
(mis)configured to be used in both secure world and Linux.

That this can happen is also reflected by the existing code that
clears any pending interrupts from "u-boot or misc causes".

Move the clearing of pending interrupts and the call to
devm_request_irq() to the end of probe.

Reviewed-by: Andi Shyti <andi.shyti at kernel.org>
Fixes: 218e1496135e ("i2c: exynos5: add support for HSI2C on Exynos5260 SoC")
Signed-off-by: Jesper Nilsson <jesper.nilsson at axis.com>
---
Changes in v2:
- Use dev_err_probe() instead of open coding it
- Dropped the return failure if we can't find a match in devicetree
- Link to v1: https://lore.kernel.org/r/20240304-i2c_exynos5-v1-1-e91c889d2025@axis.com
---
 drivers/i2c/busses/i2c-exynos5.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/i2c/busses/i2c-exynos5.c b/drivers/i2c/busses/i2c-exynos5.c
index 385ef9d9e4d4..29d7cf158612 100644
--- a/drivers/i2c/busses/i2c-exynos5.c
+++ b/drivers/i2c/busses/i2c-exynos5.c
@@ -906,23 +906,9 @@ static int exynos5_i2c_probe(struct platform_device *pdev)
 	i2c->adap.algo_data = i2c;
 	i2c->adap.dev.parent = &pdev->dev;
 
-	/* Clear pending interrupts from u-boot or misc causes */
-	exynos5_i2c_clr_pend_irq(i2c);
-
 	spin_lock_init(&i2c->lock);
 	init_completion(&i2c->msg_complete);
 
-	i2c->irq = ret = platform_get_irq(pdev, 0);
-	if (ret < 0)
-		goto err_clk;
-
-	ret = devm_request_irq(&pdev->dev, i2c->irq, exynos5_i2c_irq,
-			       IRQF_NO_SUSPEND, dev_name(&pdev->dev), i2c);
-	if (ret != 0) {
-		dev_err(&pdev->dev, "cannot request HS-I2C IRQ %d\n", i2c->irq);
-		goto err_clk;
-	}
-
 	i2c->variant = of_device_get_match_data(&pdev->dev);
 
 	ret = exynos5_hsi2c_clock_setup(i2c);
@@ -940,6 +926,20 @@ static int exynos5_i2c_probe(struct platform_device *pdev)
 	clk_disable(i2c->clk);
 	clk_disable(i2c->pclk);
 
+	/* Clear pending interrupts from u-boot or misc causes */
+	exynos5_i2c_clr_pend_irq(i2c);
+
+	i2c->irq = ret = platform_get_irq(pdev, 0);
+	if (ret < 0)
+		goto err_clk;
+
+	ret = devm_request_irq(&pdev->dev, i2c->irq, exynos5_i2c_irq,
+			       IRQF_NO_SUSPEND, dev_name(&pdev->dev), i2c);
+	if (ret != 0) {
+		dev_err(&pdev->dev, "cannot request HS-I2C IRQ %d\n", i2c->irq);
+		goto err_clk;
+	}
+
 	return 0;
 
  err_clk:

---
base-commit: 0dd3ee31125508cd67f7e7172247f05b7fd1753a
change-id: 20240228-i2c_exynos5-db13a72eec8b

Best regards,
-- 

/^JN - Jesper Nilsson
-- 
               Jesper Nilsson -- jesper.nilsson at axis.com