Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Tue, 18 Jul 2023 11:36:03 +0300
From:   Vladimir Oltean <vladimir.oltean@nxp.com>
To:     netdev@vger.kernel.org
Cc:     "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, Andrew Lunn <andrew@lunn.ch>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Maxim Georgiev <glipus@gmail.com>,
        Horatiu Vultur <horatiu.vultur@microchip.com>,
        =?utf-8?B?S8O2cnk=?= Maincent <kory.maincent@bootlin.com>,
        Maxime Chevallier <maxime.chevallier@bootlin.com>,
        Richard Cochran <richardcochran@gmail.com>,
        Vadim Fedorenko <vadim.fedorenko@linux.dev>,
        Gerhard Engleder <gerhard@engleder-embedded.com>,
        Hangbin Liu <liuhangbin@gmail.com>,
        Russell King <linux@armlinux.org.uk>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Jacob Keller <jacob.e.keller@intel.com>,
        Jay Vosburgh <j.vosburgh@gmail.com>,
        Andy Gospodarek <andy@greyhouse.net>,
        Wei Fang <wei.fang@nxp.com>,
        Shenwei Wang <shenwei.wang@nxp.com>,
        Clark Wang <xiaoning.wang@nxp.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        UNGLinuxDriver@microchip.com,
        Lars Povlsen <lars.povlsen@microchip.com>,
        Steen Hegelund <Steen.Hegelund@microchip.com>,
        Daniel Machon <daniel.machon@microchip.com>,
        Simon Horman <simon.horman@corigine.com>,
        Casper Andersson <casper.casan@gmail.com>,
        Sergey Organov <sorganov@gmail.com>,
        Michal Kubecek <mkubecek@suse.cz>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v8 net-next 11/12] net: phy: provide phylib stubs for
 hardware timestamping operations
Message-ID: <20230718083603.hl33ne4oe7f343py@skbuf>
References: <20230717152709.574773-1-vladimir.oltean@nxp.com>
 <20230717152709.574773-12-vladimir.oltean@nxp.com>
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20230717152709.574773-12-vladimir.oltean@nxp.com>
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?IyItKMnuaLY5wbk1F4F7aKNFgNFL0hK6Uhwj5ow9pbgfK9BwgRjqoP9yESZt?=
 =?us-ascii?Q?cByik8o/KL0AITlt7KKMmffAvnhS6rGIx5cZrNgbxi9Wp8ziBkL/fy/Ni7SY?=
 =?us-ascii?Q?u+9Rjx97o3YGWN23jZHsoA2Bhrg5VyQ4ePqMjEPqp3ipdGJh6oBesF1pXPXi?=
 =?us-ascii?Q?g96ksy/WbEoRKltF5L+XmxJM7DVZ84kxCpb1DsOn73uVsZljffh4Kz5IvfpG?=
 =?us-ascii?Q?9oBC69smrELHBvjjtOX71Osq5lxnGueYb9JoWpy/g1lyPQ697c+RaKwUTcnO?=
 =?us-ascii?Q?U8x9C7ktnq+ypTfVawy9J3t1qd17ljNdg2GKppsSt6Kr8utOnyDzyPMLjBWe?=
 =?us-ascii?Q?zJnCY84MKep0ebfwg/gNMuW9m9Ywgp5W+qiwSPxBbeKT1oZltR0WXXfrv4ku?=
 =?us-ascii?Q?9AFR8UaiQQ05F0b9T+kIH6NHaom23tWrmHuVfCt7OTERYp3cFl/rXkjB3U8M?=
 =?us-ascii?Q?CkQM7urN3AIRLNI37yTU3SeIzxfTpjlDITi9lEjgO4plMChNIQMR4OhE2wNm?=
 =?us-ascii?Q?deeVQj5PSIQaTHBZjrcm1o+/+RWoKAhJgLquLznbELw9Xx1l5CtAs1PCp4tL?=
 =?us-ascii?Q?O92Oj3OuYTG7+pd+PLY9WS1RlUeYwVDfY1n+5TZdRhoapb6pPcfzIGwFpxar?=
 =?us-ascii?Q?551hzpPAYL057kXDvGEZJdYzost3wcO30bu1RegfSD6KAn0mAAUTTvvJnvkI?=
 =?us-ascii?Q?ZoruGxL4TzzsHpmcB6o11gxTlCyzPTjYkcbdZpgDoWuafNYsa4C9DvrQzuqm?=
 =?us-ascii?Q?4zw7gB+2Nld0uxCYnrxLcLF8bOKVviIcUlmWC5ryMoBsO5pN/8jk5EUjMdeB?=
 =?us-ascii?Q?LffyGzveraRzi/fXZkZ3xcAxcPp6RSCH9qdqHhL1bgLqDFIe0TiFZaCbu46d?=
 =?us-ascii?Q?Ew5Spz9f4oWSLdNOp+NH8/W7KhKQDbbr6x4PqjQR/fzZuqVOzRSCBV+2hMZT?=
 =?us-ascii?Q?CIDJOflQ8JIykwsMkMSfj1YT97ldbC3RA6E7r3KM36Eru/BULGkw6LXJdaij?=
 =?us-ascii?Q?fTj/1Y8gBnwGYhcw5uhb8vdStFYzaNp2q+A1OaEyjVhi3kw+qrSYVmPo7jwo?=
 =?us-ascii?Q?Wm9l6TOq8gHGvriCTwhqfsy36G+Hzz7PzB3FStmD+dNrpTuDEw1c2nJvTXxf?=
 =?us-ascii?Q?Aewa4tGIGJV3yGJH0N2/PcchgU7fl3IAWep80Fszh88+zDKOSVuCEg8U/xLs?=
 =?us-ascii?Q?+u0fxR/Cx3JPN7cH3kj9Nm9lQ0NBUw05uyk32N2hbQmVTulnS9esS5qFJteo?=
 =?us-ascii?Q?No6RBmjdELlXuYVo2c46hwcz4sGcBTNJ0S9/6sr0eVyRvo5a2PkqnA5aGYBc?=
 =?us-ascii?Q?GpdiyrU6Su4cDrzJ3srDRC3wMa7GbuYMQ79asmjtfRZJ5RT8dlDhBL5AqLwE?=
 =?us-ascii?Q?J77KpTOUZfyh7qZclNSdZEpm54UvlSN03uJbXft9OTZZLyjcG4Nsf4HMD1ZD?=
 =?us-ascii?Q?LTSmvMb3ZK7SoKkXgj6zs1nXMK5B3mVhmtJl5T0zd7chgfTK8w41ybgE+ImX?=
 =?us-ascii?Q?a3VNisjp1HzM7nnb/2F5ee+VteWAfE8KtStYtELok9tt9di53wj/9Bp0tYns?=
 =?us-ascii?Q?fDh0TnKLcyvDS8ftuHNLw/M6DdOM8LEizliQNViSjPX4iq3fqwq+ZT4Y2oM3?=
 =?us-ascii?Q?sg=3D=3D?=
X-OriginatorOrg: nxp.com
X-MS-Exchange-CrossTenant-Network-Message-Id: f6d754aa-78c4-4a59-4516-08db876a089d
X-MS-Exchange-CrossTenant-AuthSource: AM0PR04MB6452.eurprd04.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Jul 2023 08:36:09.5282
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 686ea1d3-bc2b-4c6f-a92c-d99c5c301635
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: j2lbcwhq1OZYSj27r3fxg2748uG2Ps6bQgM0ekyr5u3se70J6Au9Gax2YX7rESWlmThPGH2NqcGWPOOEZqrP8w==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: AS8PR04MB7830
X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE,
        RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_PASS,T_SCC_BODY_TEXT_LINE,
        URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Mon, Jul 17, 2023 at 06:27:08PM +0300, Vladimir Oltean wrote:
> net/core/dev_ioctl.c (built-in code) will want to call phy_mii_ioctl()
> for hardware timestamping purposes. This is not directly possible,
> because phy_mii_ioctl() is a symbol provided under CONFIG_PHYLIB.
> 
> Do something similar to what was done in DSA in commit 5a17818682cf
> ("net: dsa: replace NETDEV_PRE_CHANGE_HWTSTAMP notifier with a stub"),
> and arrange some indirect calls to phy_mii_ioctl() through a stub
> structure containing function pointers, that's provided by phylib as
> built-in even when CONFIG_PHYLIB=m, and which phy_init() populates at
> runtime (module insertion).
> 
> Note: maybe the ownership of the ethtool_phy_ops singleton is backwards,
> and the methods exposed by that should be later merged into phylib_stubs.
> 
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
> ---

I should use "git add" on new files more often...

Annex to this patch:

diff --git a/drivers/net/phy/stubs.c b/drivers/net/phy/stubs.c
new file mode 100644
index 000000000000..06498de2d16a
--- /dev/null
+++ b/drivers/net/phy/stubs.c
@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Stubs for PHY library functionality called by the core network stack.
+ * These are necessary because CONFIG_PHYLIB can be a module, and built-in
+ * code cannot directly call symbols exported by modules.
+ */
+#include <net/dsa_stubs.h>
+
+const struct phylib_stubs *phylib_stubs;
+EXPORT_SYMBOL_GPL(phylib_stubs);
diff --git a/include/linux/phylib_stubs.h b/include/linux/phylib_stubs.h
new file mode 100644
index 000000000000..1279f48c8a70
--- /dev/null
+++ b/include/linux/phylib_stubs.h
@@ -0,0 +1,68 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Stubs for the Network PHY library
+ */
+
+#include <linux/rtnetlink.h>
+
+struct kernel_hwtstamp_config;
+struct netlink_ext_ack;
+struct phy_device;
+
+#if IS_ENABLED(CONFIG_PHYLIB)
+
+extern const struct phylib_stubs *phylib_stubs;
+
+struct phylib_stubs {
+	int (*hwtstamp_get)(struct phy_device *phydev,
+			    struct kernel_hwtstamp_config *config);
+	int (*hwtstamp_set)(struct phy_device *phydev,
+			    struct kernel_hwtstamp_config *config,
+			    struct netlink_ext_ack *extack);
+};
+
+static inline int phy_hwtstamp_get(struct phy_device *phydev,
+				   struct kernel_hwtstamp_config *config)
+{
+	/* phylib_register_stubs() and phylib_unregister_stubs()
+	 * also run under rtnl_lock().
+	 */
+	ASSERT_RTNL();
+
+	if (!phylib_stubs)
+		return -EOPNOTSUPP;
+
+	return phylib_stubs->hwtstamp_get(phydev, config);
+}
+
+static inline int phy_hwtstamp_set(struct phy_device *phydev,
+				   struct kernel_hwtstamp_config *config,
+				   struct netlink_ext_ack *extack)
+{
+	/* phylib_register_stubs() and phylib_unregister_stubs()
+	 * also run under rtnl_lock().
+	 */
+	ASSERT_RTNL();
+
+	if (!phylib_stubs)
+		return -EOPNOTSUPP;
+
+	return phylib_stubs->hwtstamp_set(phydev, config, extack);
+}
+
+#else
+
+static inline int phy_hwtstamp_get(struct phy_device *phydev,
+				   struct kernel_hwtstamp_config *config)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int phy_hwtstamp_set(struct phy_device *phydev,
+				   struct kernel_hwtstamp_config *config,
+				   struct netlink_ext_ack *extack)
+{
+	return -EOPNOTSUPP;
+}
+
+#endif