[PATCH net-next] net: dsa: microchip: Add suspend/resume support to KSZ DSA driver

[<Tristram.Ha@microchip.com>]

From: Tristram Ha <tristram.ha@microchip.com>

The KSZ DSA driver starts a timer to read MIB counters periodically to
avoid count overrun.  During system suspend this will give an error for
not able to write to register as the SPI system returns an error when
it is in suspend state.  This implementation stops the timer when the
system goes into suspend and restarts it when resumed.

Signed-off-by: Tristram Ha <tristram.ha@microchip.com>
---
 drivers/net/dsa/microchip/ksz9477_i2c.c |  4 +++
 drivers/net/dsa/microchip/ksz_common.c  | 37 +++++++++++++++++++++++++
 drivers/net/dsa/microchip/ksz_common.h  |  2 ++
 drivers/net/dsa/microchip/ksz_spi.c     |  4 +++
 4 files changed, 47 insertions(+)

diff --git a/drivers/net/dsa/microchip/ksz9477_i2c.c b/drivers/net/dsa/microchip/ksz9477_i2c.c
index 1c6d7fc16772..a2beb27459f1 100644
--- a/drivers/net/dsa/microchip/ksz9477_i2c.c
+++ b/drivers/net/dsa/microchip/ksz9477_i2c.c
@@ -127,10 +127,14 @@ static const struct of_device_id ksz9477_dt_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, ksz9477_dt_ids);
 
+static DEFINE_SIMPLE_DEV_PM_OPS(ksz_i2c_pm_ops,
+				ksz_switch_suspend, ksz_switch_resume);
+
 static struct i2c_driver ksz9477_i2c_driver = {
 	.driver = {
 		.name	= "ksz9477-switch",
 		.of_match_table = ksz9477_dt_ids,
+		.pm = &ksz_i2c_pm_ops,
 	},
 	.probe = ksz9477_i2c_probe,
 	.remove	= ksz9477_i2c_remove,
diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
index df314724e6a7..a8dac7ff6b81 100644
--- a/drivers/net/dsa/microchip/ksz_common.c
+++ b/drivers/net/dsa/microchip/ksz_common.c
@@ -4586,6 +4586,23 @@ static int ksz_hsr_leave(struct dsa_switch *ds, int port,
 	return 0;
 }
 
+static int ksz_suspend(struct dsa_switch *ds)
+{
+	struct ksz_device *dev = ds->priv;
+
+	cancel_delayed_work_sync(&dev->mib_read);
+	return 0;
+}
+
+static int ksz_resume(struct dsa_switch *ds)
+{
+	struct ksz_device *dev = ds->priv;
+
+	if (dev->mib_read_interval)
+		schedule_delayed_work(&dev->mib_read, dev->mib_read_interval);
+	return 0;
+}
+
 static const struct dsa_switch_ops ksz_switch_ops = {
 	.get_tag_protocol	= ksz_get_tag_protocol,
 	.connect_tag_protocol   = ksz_connect_tag_protocol,
@@ -4626,6 +4643,8 @@ static const struct dsa_switch_ops ksz_switch_ops = {
 	.port_max_mtu		= ksz_max_mtu,
 	.get_wol		= ksz_get_wol,
 	.set_wol		= ksz_set_wol,
+	.suspend		= ksz_suspend,
+	.resume			= ksz_resume,
 	.get_ts_info		= ksz_get_ts_info,
 	.port_hwtstamp_get	= ksz_hwtstamp_get,
 	.port_hwtstamp_set	= ksz_hwtstamp_set,
@@ -5126,6 +5145,24 @@ void ksz_switch_remove(struct ksz_device *dev)
 }
 EXPORT_SYMBOL(ksz_switch_remove);
 
+#ifdef CONFIG_PM_SLEEP
+int ksz_switch_suspend(struct device *dev)
+{
+	struct ksz_device *priv = dev_get_drvdata(dev);
+
+	return dsa_switch_suspend(priv->ds);
+}
+EXPORT_SYMBOL(ksz_switch_suspend);
+
+int ksz_switch_resume(struct device *dev)
+{
+	struct ksz_device *priv = dev_get_drvdata(dev);
+
+	return dsa_switch_resume(priv->ds);
+}
+EXPORT_SYMBOL(ksz_switch_resume);
+#endif
+
 MODULE_AUTHOR("Woojung Huh <Woojung.Huh@microchip.com>");
 MODULE_DESCRIPTION("Microchip KSZ Series Switch DSA Driver");
 MODULE_LICENSE("GPL");
diff --git a/drivers/net/dsa/microchip/ksz_common.h b/drivers/net/dsa/microchip/ksz_common.h
index b3bb75ca0796..2bc96127a447 100644
--- a/drivers/net/dsa/microchip/ksz_common.h
+++ b/drivers/net/dsa/microchip/ksz_common.h
@@ -444,6 +444,8 @@ struct ksz_dev_ops {
 struct ksz_device *ksz_switch_alloc(struct device *base, void *priv);
 int ksz_switch_register(struct ksz_device *dev);
 void ksz_switch_remove(struct ksz_device *dev);
+int ksz_switch_suspend(struct device *dev);
+int ksz_switch_resume(struct device *dev);
 
 void ksz_init_mib_timer(struct ksz_device *dev);
 bool ksz_is_port_mac_global_usable(struct dsa_switch *ds, int port);
diff --git a/drivers/net/dsa/microchip/ksz_spi.c b/drivers/net/dsa/microchip/ksz_spi.c
index 108a958dc356..b633d263098c 100644
--- a/drivers/net/dsa/microchip/ksz_spi.c
+++ b/drivers/net/dsa/microchip/ksz_spi.c
@@ -239,10 +239,14 @@ static const struct spi_device_id ksz_spi_ids[] = {
 };
 MODULE_DEVICE_TABLE(spi, ksz_spi_ids);
 
+static DEFINE_SIMPLE_DEV_PM_OPS(ksz_spi_pm_ops,
+				ksz_switch_suspend, ksz_switch_resume);
+
 static struct spi_driver ksz_spi_driver = {
 	.driver = {
 		.name	= "ksz-switch",
 		.of_match_table = ksz_dt_ids,
+		.pm = &ksz_spi_pm_ops,
 	},
 	.id_table = ksz_spi_ids,
 	.probe	= ksz_spi_probe,
-- 
2.34.1