[PATCH] i2c: sh_mobile: Mark adapter suspended during suspend

[Geert Uytterhoeven <geert+renesas@glider.be>]

When a driver tries to send an I2C message while the adapter is
suspended, this typically fails with:

    i2c-sh_mobile e60b0000.i2c: Transfer request timed out

Avoid accessing the adapter while it is suspended by marking it
suspended during suspend.  This allows the I2C core to catch this, and
print a warning:

    WARNING: CPU: 1 PID: 13 at drivers/i2c/i2c-core.h:54
__i2c_transfer+0x4a4/0x4e4
    i2c i2c-6: Transfer while suspended

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
This follows the same approach as commit 18569fa89a4db9ed ("i2c: rcar:
add suspend/resume support").
Exposed by commit dc279ac6e5b4e06e ("cpufreq: dt: Refactor
initialization to handle probe deferral properly") in linux-next, which
tries to talk to the PMIC on r8a7791/koelsch while the I2C controller is
suspended.
---
 drivers/i2c/busses/i2c-sh_mobile.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/drivers/i2c/busses/i2c-sh_mobile.c b/drivers/i2c/busses/i2c-sh_mobile.c
index bdd60770779ad523..3ae6ca21a02c6b9f 100644
--- a/drivers/i2c/busses/i2c-sh_mobile.c
+++ b/drivers/i2c/busses/i2c-sh_mobile.c
@@ -956,10 +956,38 @@ static int sh_mobile_i2c_remove(struct platform_device *dev)
 	return 0;
 }
 
+#ifdef CONFIG_PM_SLEEP
+static int sh_mobile_i2c_suspend(struct device *dev)
+{
+	struct sh_mobile_i2c_data *pd = dev_get_drvdata(dev);
+
+	i2c_mark_adapter_suspended(&pd->adap);
+	return 0;
+}
+
+static int sh_mobile_i2c_resume(struct device *dev)
+{
+	struct sh_mobile_i2c_data *pd = dev_get_drvdata(dev);
+
+	i2c_mark_adapter_resumed(&pd->adap);
+	return 0;
+}
+
+static const struct dev_pm_ops sh_mobile_i2c_pm_ops = {
+	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(sh_mobile_i2c_suspend,
+				      sh_mobile_i2c_resume)
+};
+
+#define DEV_PM_OPS (&sh_mobile_i2c_pm_ops)
+#else
+#define DEV_PM_OPS NULL
+#endif /* CONFIG_PM_SLEEP */
+
 static struct platform_driver sh_mobile_i2c_driver = {
 	.driver		= {
 		.name		= "i2c-sh_mobile",
 		.of_match_table = sh_mobile_i2c_dt_ids,
+		.pm	= DEV_PM_OPS,
 	},
 	.probe		= sh_mobile_i2c_probe,
 	.remove		= sh_mobile_i2c_remove,
-- 
2.17.1