[PATCH 1/4] i2c: riic: Abort the transfer on completion timeout

[Claudiu Beznea <claudiu.beznea@kernel.org>]

From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

riic_xfer() configures a transfer and waits for the interrupt handler to
signal its completion. If the completion times out, the device may be
powered off through runtime PM. However, the transfer interrupt may still
fire after the timeout.

To avoid cases where riic_xfer() powers off the device (via runtime PM)
while the interrupt handler is still running, disable and synchronize the
interrupts after the completion times out.

Fixes: 310c18a41450 ("i2c: riic: add driver")
Cc: stable@vger.kernel.org
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
---

 drivers/i2c/busses/i2c-riic.c | 33 +++++++++++++++++++++++++++------
 1 file changed, 27 insertions(+), 6 deletions(-)

diff --git a/drivers/i2c/busses/i2c-riic.c b/drivers/i2c/busses/i2c-riic.c
index 9e3595b3623e..68d359ce2e66 100644
--- a/drivers/i2c/busses/i2c-riic.c
+++ b/drivers/i2c/busses/i2c-riic.c
@@ -112,6 +112,7 @@ struct riic_dev {
 	void __iomem *base;
 	u8 *buf;
 	struct i2c_msg *msg;
+	int *irqs;
 	int bytes_left;
 	int err;
 	int is_last;
@@ -165,6 +166,20 @@ static int riic_bus_barrier(struct riic_dev *riic)
 	return 0;
 }
 
+static void riic_abort_xfer(struct riic_dev *riic)
+{
+	/*
+	 * Disable interrupts. Read back registers to confirm writes have
+	 * fully propagated.
+	 */
+	riic_writeb(riic, 0, RIIC_ICIER);
+	riic_readb(riic, RIIC_ICIER);
+
+	/* Synchronize IRQs */
+	for (unsigned int i = 0; i < riic->info->num_irqs; i++)
+		synchronize_irq(riic->irqs[i]);
+}
+
 static int riic_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 {
 	struct riic_dev *riic = i2c_get_adapdata(adap);
@@ -196,8 +211,10 @@ static int riic_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 		riic_writeb(riic, start_bit, RIIC_ICCR2);
 
 		time_left = wait_for_completion_timeout(&riic->msg_done, riic->adapter.timeout);
-		if (time_left == 0)
+		if (time_left == 0) {
+			riic_abort_xfer(riic);
 			riic->err = -ETIMEDOUT;
+		}
 
 		if (riic->err)
 			break;
@@ -543,16 +560,20 @@ static int riic_i2c_probe(struct platform_device *pdev)
 
 	riic->info = of_device_get_match_data(dev);
 
+	riic->irqs = devm_kcalloc(&pdev->dev, riic->info->num_irqs,
+				  sizeof(*riic->irqs), GFP_KERNEL);
+	if (!riic->irqs)
+		return -ENOMEM;
+
 	for (i = 0; i < riic->info->num_irqs; i++) {
 		const struct riic_irq_desc *irq_desc;
-		int irq;
 
 		irq_desc = &riic->info->irqs[i];
-		irq = platform_get_irq(pdev, irq_desc->res_num);
-		if (irq < 0)
-			return irq;
+		riic->irqs[i] = platform_get_irq(pdev, irq_desc->res_num);
+		if (riic->irqs[i] < 0)
+			return riic->irqs[i];
 
-		ret = devm_request_irq(dev, irq, irq_desc->isr, 0, irq_desc->name, riic);
+		ret = devm_request_irq(dev, riic->irqs[i], irq_desc->isr, 0, irq_desc->name, riic);
 		if (ret)
 			return dev_err_probe(dev, ret, "failed to request irq %s\n",
 					     irq_desc->name);
-- 
2.43.0