Message-Id: <20170730140646.11781-1-niklas.soderlund+renesas@ragnatech.se>
Date:   Sun, 30 Jul 2017 16:06:46 +0200
From:   Niklas Söderlund 
        <niklas.soderlund+renesas@...natech.se>
To:     Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
Cc:     Geert Uytterhoeven <geert@...ux-m68k.org>, netdev@...r.kernel.org,
        linux-renesas-soc@...r.kernel.org,
        Niklas Söderlund 
        <niklas.soderlund+renesas@...natech.se>
Subject: [PATCH v2] ravb: add wake-on-lan support via magic packet

WoL is enabled in the suspend callback by setting MagicPacket detection
and disabling all interrupts expect MagicPacket. In the resume path the
driver needs to reset the hardware to rearm the WoL logic, this prevents
the driver from simply restoring the registers and to take advantage of
that ravb was not suspended to reduce resume time. To reset the
hardware the driver closes the device, sets it in reset mode and reopens
the device just like it would do in a normal suspend/resume scenario
without WoL enabled, but it both closes and opens the device in the
resume callback since the device needs to be reset for WoL to work.

One quirk needed for WoL is that the module clock needs to be prevented
from being switched off by Runtime PM. To keep the clock alive the
suspend callback need to call clk_enable() directly to increase the
usage count of the clock. Then when Runtime PM decreases the clock usage
count it won't reach 0 and be switched off.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@...natech.se>
---
 drivers/net/ethernet/renesas/ravb.h      |   2 +
 drivers/net/ethernet/renesas/ravb_main.c | 130 ++++++++++++++++++++++++++++++-
 2 files changed, 128 insertions(+), 4 deletions(-)

Changes from v1
- Fix issue where device would fail to resume from PSCI suspend if WoL 
  was enabled, reported by Geert. The fault was that the clock driver 
  thinks the clock is on, but PSCI have disabled it, added workaround 
  for this in ravb driver which can be removed once the clock driver is 
  aware of the PSCI behavior.
- Only try to restore from wol wake up if netif is running, since this 
  is a condition to enable wol in the first place this was a bug in v1.


diff --git a/drivers/net/ethernet/renesas/ravb.h b/drivers/net/ethernet/renesas/ravb.h
index 0525bd696d5d02e5..96a27b00c90e212a 100644
--- a/drivers/net/ethernet/renesas/ravb.h
+++ b/drivers/net/ethernet/renesas/ravb.h
@@ -991,6 +991,7 @@ struct ravb_private {
 	struct net_device *ndev;
 	struct platform_device *pdev;
 	void __iomem *addr;
+	struct clk *clk;
 	struct mdiobb_ctrl mdiobb;
 	u32 num_rx_ring[NUM_RX_QUEUE];
 	u32 num_tx_ring[NUM_TX_QUEUE];
@@ -1033,6 +1034,7 @@ struct ravb_private {
 
 	unsigned no_avb_link:1;
 	unsigned avb_link_active_low:1;
+	unsigned wol_enabled:1;
 };
 
 static inline u32 ravb_read(struct net_device *ndev, enum ravb_reg reg)
diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index 5931e859876c2aee..3d399f85417a83cf 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -680,6 +680,9 @@ static void ravb_emac_interrupt_unlocked(struct net_device *ndev)
 
 	ecsr = ravb_read(ndev, ECSR);
 	ravb_write(ndev, ecsr, ECSR);	/* clear interrupt */
+
+	if (ecsr & ECSR_MPD)
+		pm_wakeup_event(&priv->pdev->dev, 0);
 	if (ecsr & ECSR_ICD)
 		ndev->stats.tx_carrier_errors++;
 	if (ecsr & ECSR_LCHNG) {
@@ -1330,6 +1333,33 @@ static int ravb_get_ts_info(struct net_device *ndev,
 	return 0;
 }
 
+static void ravb_get_wol(struct net_device *ndev, struct ethtool_wolinfo *wol)
+{
+	struct ravb_private *priv = netdev_priv(ndev);
+
+	wol->supported = 0;
+	wol->wolopts = 0;
+
+	if (priv->clk) {
+		wol->supported = WAKE_MAGIC;
+		wol->wolopts = priv->wol_enabled ? WAKE_MAGIC : 0;
+	}
+}
+
+static int ravb_set_wol(struct net_device *ndev, struct ethtool_wolinfo *wol)
+{
+	struct ravb_private *priv = netdev_priv(ndev);
+
+	if (!priv->clk || wol->wolopts & ~WAKE_MAGIC)
+		return -EOPNOTSUPP;
+
+	priv->wol_enabled = !!(wol->wolopts & WAKE_MAGIC);
+
+	device_set_wakeup_enable(&priv->pdev->dev, priv->wol_enabled);
+
+	return 0;
+}
+
 static const struct ethtool_ops ravb_ethtool_ops = {
 	.nway_reset		= ravb_nway_reset,
 	.get_msglevel		= ravb_get_msglevel,
@@ -1343,6 +1373,8 @@ static const struct ethtool_ops ravb_ethtool_ops = {
 	.get_ts_info		= ravb_get_ts_info,
 	.get_link_ksettings	= ravb_get_link_ksettings,
 	.set_link_ksettings	= ravb_set_link_ksettings,
+	.get_wol		= ravb_get_wol,
+	.set_wol		= ravb_set_wol,
 };
 
 static inline int ravb_hook_irq(unsigned int irq, irq_handler_t handler,
@@ -2041,6 +2073,11 @@ static int ravb_probe(struct platform_device *pdev)
 
 	priv->chip_id = chip_id;
 
+	/* Get clock, if not found that's OK but Wake-On-Lan is unavailable */
+	priv->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(priv->clk))
+		priv->clk = NULL;
+
 	/* Set function */
 	ndev->netdev_ops = &ravb_netdev_ops;
 	ndev->ethtool_ops = &ravb_ethtool_ops;
@@ -2107,6 +2144,9 @@ static int ravb_probe(struct platform_device *pdev)
 	if (error)
 		goto out_napi_del;
 
+	if (priv->clk)
+		device_set_wakeup_capable(&pdev->dev, 1);
+
 	/* Print device information */
 	netdev_info(ndev, "Base address at %#x, %pM, IRQ %d.\n",
 		    (u32)ndev->base_addr, ndev->dev_addr, ndev->irq);
@@ -2160,15 +2200,66 @@ static int ravb_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static int ravb_wol_setup(struct net_device *ndev)
+{
+	struct ravb_private *priv = netdev_priv(ndev);
+
+	/* Disable interrupts by clearing the interrupt masks. */
+	ravb_write(ndev, 0, RIC0);
+	ravb_write(ndev, 0, RIC2);
+	ravb_write(ndev, 0, TIC);
+
+	/* Only allow ECI interrupts */
+	synchronize_irq(priv->emac_irq);
+	napi_disable(&priv->napi[RAVB_NC]);
+	napi_disable(&priv->napi[RAVB_BE]);
+	ravb_write(ndev, ECSIPR_MPDIP, ECSIPR);
+
+	/* Enable MagicPacket */
+	ravb_modify(ndev, ECMR, ECMR_MPDE, ECMR_MPDE);
+
+	/* Increased clock usage so device won't be suspended */
+	clk_enable(priv->clk);
+
+	return enable_irq_wake(priv->emac_irq);
+}
+
+static int ravb_wol_restore(struct net_device *ndev)
+{
+	struct ravb_private *priv = netdev_priv(ndev);
+	int ret;
+
+	napi_enable(&priv->napi[RAVB_NC]);
+	napi_enable(&priv->napi[RAVB_BE]);
+
+	/* Disable MagicPacket */
+	ravb_modify(ndev, ECMR, ECMR_MPDE, 0);
+
+	ret = ravb_close(ndev);
+	if (ret < 0)
+		return ret;
+
+	/* Restore clock usage count */
+	clk_disable(priv->clk);
+
+	return disable_irq_wake(priv->emac_irq);
+}
+
 static int __maybe_unused ravb_suspend(struct device *dev)
 {
 	struct net_device *ndev = dev_get_drvdata(dev);
-	int ret = 0;
+	struct ravb_private *priv = netdev_priv(ndev);
+	int ret;
 
-	if (netif_running(ndev)) {
-		netif_device_detach(ndev);
+	if (!netif_running(ndev))
+		return 0;
+
+	netif_device_detach(ndev);
+
+	if (priv->wol_enabled)
+		ret = ravb_wol_setup(ndev);
+	else
 		ret = ravb_close(ndev);
-	}
 
 	return ret;
 }
@@ -2179,6 +2270,32 @@ static int __maybe_unused ravb_resume(struct device *dev)
 	struct ravb_private *priv = netdev_priv(ndev);
 	int ret = 0;
 
+	/* Reduce the usecount of the clock to zero and then
+	 * restore it to its original value. This is done to force
+	 * the clock to be re-enabled which is a workaround
+	 * for renesas-cpg-mssr driver which do not enable clocks
+	 * when resuming from PSCI suspend/resume.
+	 *
+	 * Without this workaround the driver fails to communicate
+	 * with the hardware if WoL was enabled when the system
+	 * entered PSCI suspend. This is due to that if WoL is enabled
+	 * we explicitly keep the clock from being turned off when
+	 * suspending, but in PSCI sleep power is cut so the clock
+	 * is disabled anyhow, the clock driver is not aware of this
+	 * so the clock is not turned back on when resuming.
+	 *
+	 * TODO: once the renesas-cpg-mssr suspend/resume is working
+	 *       this clock dance should be removed.
+	 */
+	clk_disable(priv->clk);
+	clk_disable(priv->clk);
+	clk_enable(priv->clk);
+	clk_enable(priv->clk);
+
+	/* If WoL is enabled set reset mode to rearm the WoL logic */
+	if (priv->wol_enabled)
+		ravb_write(ndev, CCC_OPC_RESET, CCC);
+
 	/* All register have been reset to default values.
 	 * Restore all registers which where setup at probe time and
 	 * reopen device if it was running before system suspended.
@@ -2202,6 +2319,11 @@ static int __maybe_unused ravb_resume(struct device *dev)
 	ravb_write(ndev, priv->desc_bat_dma, DBAT);
 
 	if (netif_running(ndev)) {
+		if (priv->wol_enabled) {
+			ret = ravb_wol_restore(ndev);
+			if (ret)
+				return ret;
+		}
 		ret = ravb_open(ndev);
 		if (ret < 0)
 			return ret;
-- 
2.13.3

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