net: dsa: b53: Add SerDes support

Add support for the Northstar Plus SerDes which is accessed through a
special page of the switch. Since this is something that most people
probably will not want to use, make it a configurable option with a
default on ARCH_BCM_NSP where it is the most useful currently.

The SerDes supports both SGMII and 1000baseX modes for both lanes, and
2500baseX for one of the lanes, and is internally looking like a
seemingly standard MII PHY, except for the few bits that got repurposed.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 217 insertions, 0 deletions

diff --git a/drivers/net/dsa/b53/b53_serdes.c b/drivers/net/dsa/b53/b53_serdes.c
new file mode 100644
index 000000000000..b45c55e0b8b4
--- /dev/null
+++ b/drivers/net/dsa/b53/b53_serdes.c
@@ -0,0 +1,217 @@
+// SPDX-License-Identifier: GPL-2.0 or BSD-3-Clause
+/*
+ * Northstar Plus switch SerDes/SGMII PHY main logic
+ *
+ * Copyright (C) 2018 Florian Fainelli <f.fainelli@gmail.com>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/phy.h>
+#include <linux/phylink.h>
+#include <net/dsa.h>
+
+#include "b53_priv.h"
+#include "b53_serdes.h"
+#include "b53_regs.h"
+
+static void b53_serdes_write_blk(struct b53_device *dev, u8 offset, u16 block,
+				 u16 value)
+{
+	b53_write16(dev, B53_SERDES_PAGE, B53_SERDES_BLKADDR, block);
+	b53_write16(dev, B53_SERDES_PAGE, offset, value);
+}
+
+static u16 b53_serdes_read_blk(struct b53_device *dev, u8 offset, u16 block)
+{
+	u16 value;
+
+	b53_write16(dev, B53_SERDES_PAGE, B53_SERDES_BLKADDR, block);
+	b53_read16(dev, B53_SERDES_PAGE, offset, &value);
+
+	return value;
+}
+
+static void b53_serdes_set_lane(struct b53_device *dev, u8 lane)
+{
+	if (dev->serdes_lane == lane)
+		return;
+
+	WARN_ON(lane > 1);
+
+	b53_serdes_write_blk(dev, B53_SERDES_LANE,
+			     SERDES_XGXSBLK0_BLOCKADDRESS, lane);
+	dev->serdes_lane = lane;
+}
+
+static void b53_serdes_write(struct b53_device *dev, u8 lane,
+			     u8 offset, u16 block, u16 value)
+{
+	b53_serdes_set_lane(dev, lane);
+	b53_serdes_write_blk(dev, offset, block, value);
+}
+
+static u16 b53_serdes_read(struct b53_device *dev, u8 lane,
+			   u8 offset, u16 block)
+{
+	b53_serdes_set_lane(dev, lane);
+	return b53_serdes_read_blk(dev, offset, block);
+}
+
+void b53_serdes_config(struct b53_device *dev, int port, unsigned int mode,
+		       const struct phylink_link_state *state)
+{
+	u8 lane = b53_serdes_map_lane(dev, port);
+	u16 reg;
+
+	if (lane == B53_INVALID_LANE)
+		return;
+
+	reg = b53_serdes_read(dev, lane, B53_SERDES_DIGITAL_CONTROL(1),
+			      SERDES_DIGITAL_BLK);
+	if (state->interface == PHY_INTERFACE_MODE_1000BASEX)
+		reg |= FIBER_MODE_1000X;
+	else
+		reg &= ~FIBER_MODE_1000X;
+	b53_serdes_write(dev, lane, B53_SERDES_DIGITAL_CONTROL(1),
+			 SERDES_DIGITAL_BLK, reg);
+}
+EXPORT_SYMBOL(b53_serdes_config);
+
+void b53_serdes_an_restart(struct b53_device *dev, int port)
+{
+	u8 lane = b53_serdes_map_lane(dev, port);
+	u16 reg;
+
+	if (lane == B53_INVALID_LANE)
+		return;
+
+	reg = b53_serdes_read(dev, lane, B53_SERDES_MII_REG(MII_BMCR),
+			      SERDES_MII_BLK);
+	reg |= BMCR_ANRESTART;
+	b53_serdes_write(dev, lane, B53_SERDES_MII_REG(MII_BMCR),
+			 SERDES_MII_BLK, reg);
+}
+EXPORT_SYMBOL(b53_serdes_an_restart);
+
+int b53_serdes_link_state(struct b53_device *dev, int port,
+			  struct phylink_link_state *state)
+{
+	u8 lane = b53_serdes_map_lane(dev, port);
+	u16 dig, bmcr, bmsr;
+
+	if (lane == B53_INVALID_LANE)
+		return 1;
+
+	dig = b53_serdes_read(dev, lane, B53_SERDES_DIGITAL_STATUS,
+			      SERDES_DIGITAL_BLK);
+	bmcr = b53_serdes_read(dev, lane, B53_SERDES_MII_REG(MII_BMCR),
+			       SERDES_MII_BLK);
+	bmsr = b53_serdes_read(dev, lane, B53_SERDES_MII_REG(MII_BMSR),
+			       SERDES_MII_BLK);
+
+	switch ((dig >> SPEED_STATUS_SHIFT) & SPEED_STATUS_MASK) {
+	case SPEED_STATUS_10:
+		state->speed = SPEED_10;
+		break;
+	case SPEED_STATUS_100:
+		state->speed = SPEED_100;
+		break;
+	case SPEED_STATUS_1000:
+		state->speed = SPEED_1000;
+		break;
+	default:
+	case SPEED_STATUS_2500:
+		state->speed = SPEED_2500;
+		break;
+	}
+
+	state->duplex = dig & DUPLEX_STATUS ? DUPLEX_FULL : DUPLEX_HALF;
+	state->an_enabled = !!(bmcr & BMCR_ANENABLE);
+	state->an_complete = !!(bmsr & BMSR_ANEGCOMPLETE);
+	state->link = !!(dig & LINK_STATUS);
+	if (dig & PAUSE_RESOLUTION_RX_SIDE)
+		state->pause |= MLO_PAUSE_RX;
+	if (dig & PAUSE_RESOLUTION_TX_SIDE)
+		state->pause |= MLO_PAUSE_TX;
+
+	return 0;
+}
+EXPORT_SYMBOL(b53_serdes_link_state);
+
+void b53_serdes_link_set(struct b53_device *dev, int port, unsigned int mode,
+			 phy_interface_t interface, bool link_up)
+{
+	u8 lane = b53_serdes_map_lane(dev, port);
+	u16 reg;
+
+	if (lane == B53_INVALID_LANE)
+		return;
+
+	reg = b53_serdes_read(dev, lane, B53_SERDES_MII_REG(MII_BMCR),
+			      SERDES_MII_BLK);
+	if (link_up)
+		reg &= ~BMCR_PDOWN;
+	else
+		reg |= BMCR_PDOWN;
+	b53_serdes_write(dev, lane, B53_SERDES_MII_REG(MII_BMCR),
+			 SERDES_MII_BLK, reg);
+}
+EXPORT_SYMBOL(b53_serdes_link_set);
+
+void b53_serdes_phylink_validate(struct b53_device *dev, int port,
+				 unsigned long *supported,
+				 struct phylink_link_state *state)
+{
+	u8 lane = b53_serdes_map_lane(dev, port);
+
+	if (lane == B53_INVALID_LANE)
+		return;
+
+	switch (lane) {
+	case 0:
+		phylink_set(supported, 2500baseX_Full);
+		/* fallthrough */
+	case 1:
+		phylink_set(supported, 1000baseX_Full);
+		break;
+	default:
+		break;
+	}
+}
+EXPORT_SYMBOL(b53_serdes_phylink_validate);
+
+int b53_serdes_init(struct b53_device *dev, int port)
+{
+	u8 lane = b53_serdes_map_lane(dev, port);
+	u16 id0, msb, lsb;
+
+	if (lane == B53_INVALID_LANE)
+		return -EINVAL;
+
+	id0 = b53_serdes_read(dev, lane, B53_SERDES_ID0, SERDES_ID0);
+	msb = b53_serdes_read(dev, lane, B53_SERDES_MII_REG(MII_PHYSID1),
+			      SERDES_MII_BLK);
+	lsb = b53_serdes_read(dev, lane, B53_SERDES_MII_REG(MII_PHYSID2),
+			      SERDES_MII_BLK);
+	if (id0 == 0 || id0 == 0xffff) {
+		dev_err(dev->dev, "SerDes not initialized, check settings\n");
+		return -ENODEV;
+	}
+
+	dev_info(dev->dev,
+		 "SerDes lane %d, model: %d, rev %c%d (OUI: 0x%08x)\n",
+		 lane, id0 & SERDES_ID0_MODEL_MASK,
+		 (id0 >> SERDES_ID0_REV_LETTER_SHIFT) + 0x41,
+		 (id0 >> SERDES_ID0_REV_NUM_SHIFT) & SERDES_ID0_REV_NUM_MASK,
+		 (u32)msb << 16 | lsb);
+
+	return 0;
+}
+EXPORT_SYMBOL(b53_serdes_init);
+
+MODULE_AUTHOR("Florian Fainelli <f.fainelli@gmail.com>");
+MODULE_DESCRIPTION("B53 Switch SerDes driver");
+MODULE_LICENSE("Dual BSD/GPL");