linux-kernel - [PATCH 1/2] i2c: sprd: Prevent i2c accesses after suspend is called

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Date:   Mon,  9 Apr 2018 14:40:54 +0800
From:   Baolin Wang <baolin.wang@...aro.org>
To:     wsa@...-dreams.de
Cc:     broonie@...nel.org, baolin.wang@...aro.org,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] i2c: sprd: Prevent i2c accesses after suspend is called

Add one flag to indicate if the i2c controller has been in suspend state,
which can prevent i2c accesses after i2c controller is suspended following
system suspend.

Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
---
 drivers/i2c/busses/i2c-sprd.c |   16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/i2c/busses/i2c-sprd.c b/drivers/i2c/busses/i2c-sprd.c
index 25fcc3c..2fdad63 100644
--- a/drivers/i2c/busses/i2c-sprd.c
+++ b/drivers/i2c/busses/i2c-sprd.c
@@ -86,6 +86,7 @@ struct sprd_i2c {
 	u32 count;
 	int irq;
 	int err;
+	bool is_suspended;
 };
 
 static void sprd_i2c_set_count(struct sprd_i2c *i2c_dev, u32 count)
@@ -283,6 +284,9 @@ static int sprd_i2c_master_xfer(struct i2c_adapter *i2c_adap,
 	struct sprd_i2c *i2c_dev = i2c_adap->algo_data;
 	int im, ret;
 
+	if (i2c_dev->is_suspended)
+		return -EBUSY;
+
 	ret = pm_runtime_get_sync(i2c_dev->dev);
 	if (ret < 0)
 		return ret;
@@ -586,11 +590,23 @@ static int sprd_i2c_remove(struct platform_device *pdev)
 
 static int __maybe_unused sprd_i2c_suspend_noirq(struct device *pdev)
 {
+	struct sprd_i2c *i2c_dev = dev_get_drvdata(pdev);
+
+	i2c_lock_adapter(&i2c_dev->adap);
+	i2c_dev->is_suspended = true;
+	i2c_unlock_adapter(&i2c_dev->adap);
+
 	return pm_runtime_force_suspend(pdev);
 }
 
 static int __maybe_unused sprd_i2c_resume_noirq(struct device *pdev)
 {
+	struct sprd_i2c *i2c_dev = dev_get_drvdata(pdev);
+
+	i2c_lock_adapter(&i2c_dev->adap);
+	i2c_dev->is_suspended = false;
+	i2c_unlock_adapter(&i2c_dev->adap);
+
 	return pm_runtime_force_resume(pdev);
 }
 
-- 
1.7.9.5