net: dsa: hellcreek: Add PTP clock support

The switch has internal PTP hardware clocks. Add support for it. There are three
clocks:

 * Synchronized
 * Syntonized
 * Free running

Currently the synchronized clock is exported to user space which is a good
default for the beginning. The free running clock might be exported later
e.g. for implementing 802.1AS-2011/2020 Time Aware Bridges (TAB). The switch
also supports cross time stamping for that purpose.

The implementation adds support setting/getting the time as well as offset and
frequency adjustments. However, the clock only holds a partial timeofday
timestamp. This is why we track the seconds completely in software (see overflow
work and last_ts).

Furthermore, add the PTP multicast addresses into the FDB to forward that
packages only to the CPU port where they are processed by a PTP program.

Signed-off-by: Kamil Alkhouri <kamil.alkhouri@hs-offenburg.de>
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/dsa/hirschmann/Kconfig

@@ -3,6 +3,7 @@ config NET_DSA_HIRSCHMANN_HELLCREEK
 	tristate "Hirschmann Hellcreek TSN Switch support"
 	depends on HAS_IOMEM
 	depends on NET_DSA
+	depends on PTP_1588_CLOCK
 	select NET_DSA_TAG_HELLCREEK
 	help
 	  This driver adds support for Hirschmann Hellcreek TSN switches.

drivers/net/dsa/hirschmann/Makefile

@@ -1,2 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0
-obj-$(CONFIG_NET_DSA_HIRSCHMANN_HELLCREEK)	+= hellcreek.o
+obj-$(CONFIG_NET_DSA_HIRSCHMANN_HELLCREEK)	+= hellcreek_sw.o
+hellcreek_sw-objs := hellcreek.o
+hellcreek_sw-objs += hellcreek_ptp.o

drivers/net/dsa/hirschmann/hellcreek.c

@@ -25,6 +25,7 @@
 #include <net/dsa.h>
 
 #include "hellcreek.h"
+#include "hellcreek_ptp.h"
 
 static const struct hellcreek_counter hellcreek_counter[] = {
 	{ 0x00, "RxFiltered", },
@@ -959,6 +960,43 @@ static void hellcreek_setup_tc_identity_mapping(struct hellcreek *hellcreek)
 	}
 }
 
+static int hellcreek_setup_fdb(struct hellcreek *hellcreek)
+{
+	static struct hellcreek_fdb_entry ptp = {
+		/* MAC: 01-1B-19-00-00-00 */
+		.mac	      = { 0x01, 0x1b, 0x19, 0x00, 0x00, 0x00 },
+		.portmask     = 0x03,	/* Management ports */
+		.age	      = 0,
+		.is_obt	      = 0,
+		.pass_blocked = 0,
+		.is_static    = 1,
+		.reprio_tc    = 6,	/* TC: 6 as per IEEE 802.1AS */
+		.reprio_en    = 1,
+	};
+	static struct hellcreek_fdb_entry p2p = {
+		/* MAC: 01-80-C2-00-00-0E */
+		.mac	      = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x0e },
+		.portmask     = 0x03,	/* Management ports */
+		.age	      = 0,
+		.is_obt	      = 0,
+		.pass_blocked = 0,
+		.is_static    = 1,
+		.reprio_tc    = 6,	/* TC: 6 as per IEEE 802.1AS */
+		.reprio_en    = 1,
+	};
+	int ret;
+
+	mutex_lock(&hellcreek->reg_lock);
+	ret = __hellcreek_fdb_add(hellcreek, &ptp);
+	if (ret)
+		goto out;
+	ret = __hellcreek_fdb_add(hellcreek, &p2p);
+out:
+	mutex_unlock(&hellcreek->reg_lock);
+
+	return ret;
+}
+
 static int hellcreek_setup(struct dsa_switch *ds)
 {
 	struct hellcreek *hellcreek = ds->priv;
@@ -1009,6 +1047,14 @@ static int hellcreek_setup(struct dsa_switch *ds)
 	 */
 	ds->vlan_filtering_is_global = true;
 
+	/* Intercept _all_ PTP multicast traffic */
+	ret = hellcreek_setup_fdb(hellcreek);
+	if (ret) {
+		dev_err(hellcreek->dev,
+			"Failed to insert static PTP FDB entries\n");
+		return ret;
+	}
+
 	return 0;
 }
 
@@ -1160,6 +1206,7 @@ static int hellcreek_probe(struct platform_device *pdev)
 
 	mutex_init(&hellcreek->reg_lock);
 	mutex_init(&hellcreek->vlan_lock);
+	mutex_init(&hellcreek->ptp_lock);
 
 	hellcreek->dev = dev;
 
@@ -1175,6 +1222,18 @@ static int hellcreek_probe(struct platform_device *pdev)
 		return PTR_ERR(hellcreek->base);
 	}
 
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "ptp");
+	if (!res) {
+		dev_err(dev, "No PTP memory region provided!\n");
+		return -ENODEV;
+	}
+
+	hellcreek->ptp_base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(hellcreek->ptp_base)) {
+		dev_err(dev, "No memory available!\n");
+		return PTR_ERR(hellcreek->ptp_base);
+	}
+
 	ret = hellcreek_detect(hellcreek);
 	if (ret) {
 		dev_err(dev, "No (known) chip found!\n");
@@ -1205,15 +1264,27 @@ static int hellcreek_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	ret = hellcreek_ptp_setup(hellcreek);
+	if (ret) {
+		dev_err(dev, "Failed to setup PTP!\n");
+		goto err_ptp_setup;
+	}
+
 	platform_set_drvdata(pdev, hellcreek);
 
 	return 0;
+
+err_ptp_setup:
+	dsa_unregister_switch(hellcreek->ds);
+
+	return ret;
 }
 
 static int hellcreek_remove(struct platform_device *pdev)
 {
 	struct hellcreek *hellcreek = platform_get_drvdata(pdev);
 
+	hellcreek_ptp_free(hellcreek);
 	dsa_unregister_switch(hellcreek->ds);
 	platform_set_drvdata(pdev, NULL);
 

drivers/net/dsa/hirschmann/hellcreek.h

@@ -15,6 +15,7 @@
 #include <linux/device.h>
 #include <linux/kernel.h>
 #include <linux/mutex.h>
+#include <linux/workqueue.h>
 #include <linux/platform_data/hirschmann-hellcreek.h>
 #include <linux/ptp_clock_kernel.h>
 #include <linux/timecounter.h>
@@ -237,12 +238,19 @@ struct hellcreek {
 	const struct hellcreek_platform_data *pdata;
 	struct device *dev;
 	struct dsa_switch *ds;
+	struct ptp_clock *ptp_clock;
+	struct ptp_clock_info ptp_clock_info;
 	struct hellcreek_port *ports;
+	struct delayed_work overflow_work;
 	struct mutex reg_lock;	/* Switch IP register lock */
 	struct mutex vlan_lock;	/* VLAN bitmaps lock */
+	struct mutex ptp_lock;	/* PTP IP register lock */
 	void __iomem *base;
+	void __iomem *ptp_base;
 	u16 swcfg;		/* swcfg shadow */
 	u8 *vidmbrcfg;		/* vidmbrcfg shadow */
+	u64 seconds;		/* PTP seconds */
+	u64 last_ts;		/* Used for overflow detection */
 	size_t fdb_entries;
 };