netdev - [PATCHv4 4/4] net: cdc_ether: record speed in status method

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Message-Id: <20210330021651.30906-5-grundler@chromium.org>
Date:   Mon, 29 Mar 2021 19:16:51 -0700
From:   Grant Grundler <grundler@...omium.org>
To:     Oliver Neukum <oneukum@...e.com>, Jakub Kicinski <kuba@...nel.org>
Cc:     Roland Dreier <roland@...nel.org>, nic_swsd <nic_swsd@...ltek.com>,
        netdev <netdev@...r.kernel.org>,
        "David S . Miller" <davem@...emloft.net>,
        LKML <linux-kernel@...r.kernel.org>,
        Andrew Lunn <andrew@...n.ch>,
        Grant Grundler <GrantGrundlergrundler@...omium.org>,
        Grant Grundler <grundler@...omium.org>
Subject: [PATCHv4 4/4] net: cdc_ether: record speed in status method

From: Grant Grundler <Grant Grundler grundler@...omium.org>

Until very recently, the usbnet framework only had support functions
for devices which reported the link speed by explicitly querying the
PHY over a MDIO interface. However, the cdc_ether devices send
notifications when the link state or link speeds change and do not
expose the PHY (or modem) directly.

Support funtions (e.g. usbnet_get_link_ksettings_internal()) to directly
query state recorded by the cdc_ether driver were added in a previous patch.

Instead of cdc_ether spewing the link speed into the dmesg buffer,
record the link speed encoded in these notifications and tell the
usbnet framework to use the new functions to get link speed/state.

User space can now get the most recent link speed/state using ethtool.

v4: added to series since cdc_ether uses same notifications
    as cdc_ncm driver.

Signed-off-by: Grant Grundler <grundler@...omium.org>
---
 drivers/net/usb/cdc_ether.c | 27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/drivers/net/usb/cdc_ether.c b/drivers/net/usb/cdc_ether.c
index a9b551028659..7eb0109e9baa 100644
--- a/drivers/net/usb/cdc_ether.c
+++ b/drivers/net/usb/cdc_ether.c
@@ -92,6 +92,18 @@ void usbnet_cdc_update_filter(struct usbnet *dev)
 }
 EXPORT_SYMBOL_GPL(usbnet_cdc_update_filter);
 
+/* We need to override usbnet_*_link_ksettings in bind() */
+static const struct ethtool_ops cdc_ether_ethtool_ops = {
+	.get_link		= usbnet_get_link,
+	.nway_reset		= usbnet_nway_reset,
+	.get_drvinfo		= usbnet_get_drvinfo,
+	.get_msglevel		= usbnet_get_msglevel,
+	.set_msglevel		= usbnet_set_msglevel,
+	.get_ts_info		= ethtool_op_get_ts_info,
+	.get_link_ksettings	= usbnet_get_link_ksettings_internal,
+	.set_link_ksettings	= NULL,
+};
+
 /* probes control interface, claims data interface, collects the bulk
  * endpoints, activates data interface (if needed), maybe sets MTU.
  * all pure cdc, except for certain firmware workarounds, and knowing
@@ -310,6 +322,9 @@ int usbnet_generic_cdc_bind(struct usbnet *dev, struct usb_interface *intf)
 		return -ENODEV;
 	}
 
+	/* override ethtool_ops */
+	dev->net->ethtool_ops = &cdc_ether_ethtool_ops;
+
 	return 0;
 
 bad_desc:
@@ -379,12 +394,10 @@ EXPORT_SYMBOL_GPL(usbnet_cdc_unbind);
  * (by Brad Hards) talked with, with more functionality.
  */
 
-static void dumpspeed(struct usbnet *dev, __le32 *speeds)
+static void speed_change(struct usbnet *dev, __le32 *speeds)
 {
-	netif_info(dev, timer, dev->net,
-		   "link speeds: %u kbps up, %u kbps down\n",
-		   __le32_to_cpu(speeds[0]) / 1000,
-		   __le32_to_cpu(speeds[1]) / 1000);
+	dev->tx_speed = __le32_to_cpu(speeds[0]);
+	dev->rx_speed = __le32_to_cpu(speeds[1]);
 }
 
 void usbnet_cdc_status(struct usbnet *dev, struct urb *urb)
@@ -396,7 +409,7 @@ void usbnet_cdc_status(struct usbnet *dev, struct urb *urb)
 
 	/* SPEED_CHANGE can get split into two 8-byte packets */
 	if (test_and_clear_bit(EVENT_STS_SPLIT, &dev->flags)) {
-		dumpspeed(dev, (__le32 *) urb->transfer_buffer);
+		speed_change(dev, (__le32 *) urb->transfer_buffer);
 		return;
 	}
 
@@ -413,7 +426,7 @@ void usbnet_cdc_status(struct usbnet *dev, struct urb *urb)
 		if (urb->actual_length != (sizeof(*event) + 8))
 			set_bit(EVENT_STS_SPLIT, &dev->flags);
 		else
-			dumpspeed(dev, (__le32 *) &event[1]);
+			speed_change(dev, (__le32 *) &event[1]);
 		break;
 	/* USB_CDC_NOTIFY_RESPONSE_AVAILABLE can happen too (e.g. RNDIS),
 	 * but there are no standard formats for the response data.
-- 
2.30.1