net: dsa: microchip: Add suspend/resume support to KSZ DSA driver

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 <[e-mail]>
Reviewed-by: Andrew Lunn <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/dsa/microchip/ksz9477_i2c.c

···
 };
 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,

drivers/net/dsa/microchip/ksz_common.c

···
 	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,
···
 	.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,
···
 
 }
 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 <[e-mail]>");
 MODULE_DESCRIPTION("Microchip KSZ Series Switch DSA Driver");

drivers/net/dsa/microchip/ksz_common.h

···
 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);

drivers/net/dsa/microchip/ksz_spi.c

···
 };
 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,