From: Carlos Song <carlos.song@nxp.com>

Mark the I2C adapter as suspended during system suspend to block further
transfers, and resume it on system resume. This prevents potential hangs
when the hardware is powered down but clients still attempt I2C transfers.

Fixes: 358025ac091e ("i2c: imx: make controller available until system suspend_noirq() and from resume_noirq()")
Cc: stable@vger.kernel.org
Signed-off-by: Carlos Song <carlos.song@nxp.com>
---
Change for v4:
  - Restore hrtimer when pm_runtime_force_suspend failed when slave mode
    enabled.
Change for v3:
  - Add hrtimer_cancel in i2c_imx_suspend_noirq to cancel slave_timer for
    safe suspend in i2c slave mode.
Change for v2:
  - Call i2c_mark_adapter_suspended() before pm_runtime_force_suspend()
    to prevent potential deadlock if a transfer is active during suspend.
  - Roll back with i2c_mark_adapter_resumed() if pm_runtime_force_suspend()
    fails.
---
 drivers/i2c/busses/i2c-imx.c | 45 ++++++++++++++++++++++++++++++++++--
 1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 28313d0fad37..73317ddd5f02 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -1922,6 +1922,47 @@ static int i2c_imx_runtime_resume(struct device *dev)
 	return 0;
 }
 
+static int __maybe_unused i2c_imx_suspend_noirq(struct device *dev)
+{
+	struct imx_i2c_struct *i2c_imx = dev_get_drvdata(dev);
+	int ret;
+
+	i2c_mark_adapter_suspended(&i2c_imx->adapter);
+
+	/*
+	 * Cancel the slave timer before powering down to prevent
+	 * i2c_imx_slave_timeout() from accessing hardware registers
+	 * while the clock is disabled.
+	 */
+	hrtimer_cancel(&i2c_imx->slave_timer);
+
+	ret = pm_runtime_force_suspend(dev);
+	if (ret) {
+		i2c_mark_adapter_resumed(&i2c_imx->adapter);
+		if (i2c_imx->slave) {
+			hrtimer_forward_now(&i2c_imx->slave_timer, I2C_IMX_CHECK_DELAY);
+			hrtimer_restart(&i2c_imx->slave_timer);
+		}
+		return ret;
+	}
+
+	return 0;
+}
+
+static int __maybe_unused i2c_imx_resume_noirq(struct device *dev)
+{
+	struct imx_i2c_struct *i2c_imx = dev_get_drvdata(dev);
+	int ret;
+
+	ret = pm_runtime_force_resume(dev);
+	if (ret)
+		return ret;
+
+	i2c_mark_adapter_resumed(&i2c_imx->adapter);
+
+	return 0;
+}
+
 static int i2c_imx_suspend(struct device *dev)
 {
 	/*
@@ -1955,8 +1996,8 @@ static int i2c_imx_resume(struct device *dev)
 }
 
 static const struct dev_pm_ops i2c_imx_pm_ops = {
-	NOIRQ_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
-				  pm_runtime_force_resume)
+	NOIRQ_SYSTEM_SLEEP_PM_OPS(i2c_imx_suspend_noirq,
+				  i2c_imx_resume_noirq)
 	SYSTEM_SLEEP_PM_OPS(i2c_imx_suspend, i2c_imx_resume)
 	RUNTIME_PM_OPS(i2c_imx_runtime_suspend, i2c_imx_runtime_resume, NULL)
 };
-- 
2.43.0