net: dsa: microchip: Add KSZ8463 switch support to KSZ DSA driver

KSZ8463 switch is a 3-port switch based from KSZ8863.  Its major
difference from other KSZ SPI switches is its register access is not a
simple continual 8-bit transfer with automatic address increase but uses
a byte-enable mechanism specifying 8-bit, 16-bit, or 32-bit access.  Its
registers are also defined in 16-bit format because it shares a design
with a MAC controller using 16-bit access.  As a result some common
register accesses need to be re-arranged.

This patch adds the basic structure for using KSZ8463.  It cannot use the
same regmap table for other KSZ switches as it interprets the 16-bit
value as little-endian and its SPI commands are different.

KSZ8463 uses a byte-enable mechanism to specify 8-bit, 16-bit, and 32-bit
access.  The register is first shifted right by 2 then left by 4.  Extra
4 bits are added.  If the access is 8-bit one of the 4 bits is set.  If
the access is 16-bit two of the 4 bits are set.  If the access is 32-bit
all 4 bits are set.  The SPI command for read or write is then added.

Because of this register transformation separate SPI read and write
functions are provided for KSZ8463.

KSZ8463's internal PHYs use standard PHY register definitions so there is
no need to remap things.  However, the hardware has a bug that the high
word and low word of the PHY id are swapped.  In addition the port
registers are arranged differently so KSZ8463 has its own mapping for
port registers and PHY registers.  Therefore the PORT_CTRL_ADDR macro is
replaced with the get_port_addr helper function.

Signed-off-by: Tristram Ha <tristram.ha@microchip.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20250725001753.6330-3-Tristram.Ha@microchip.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 82 insertions, 1 deletions

diff --git a/drivers/net/dsa/microchip/ksz8.c b/drivers/net/dsa/microchip/ksz8.c
index be433b4e2b1c..3761a81a7320 100644
--- a/drivers/net/dsa/microchip/ksz8.c
+++ b/drivers/net/dsa/microchip/ksz8.c
@@ -3,6 +3,7 @@
  * Microchip KSZ8XXX series switch driver
  *
  * It supports the following switches:
+ * - KSZ8463
  * - KSZ8863, KSZ8873 aka KSZ88X3
  * - KSZ8895, KSZ8864 aka KSZ8895 family
  * - KSZ8794, KSZ8795, KSZ8765 aka KSZ87XX
@@ -41,7 +42,8 @@ static void ksz_cfg(struct ksz_device *dev, u32 addr, u8 bits, bool set)
 static void ksz_port_cfg(struct ksz_device *dev, int port, int offset, u8 bits,
 			 bool set)
 {
-	regmap_update_bits(ksz_regmap_8(dev), PORT_CTRL_ADDR(port, offset),
+	regmap_update_bits(ksz_regmap_8(dev),
+			   dev->dev_ops->get_port_addr(port, offset),
 			   bits, set ? bits : 0);
 }
 
@@ -194,6 +196,7 @@ int ksz8_change_mtu(struct ksz_device *dev, int port, int mtu)
 	case KSZ8794_CHIP_ID:
 	case KSZ8765_CHIP_ID:
 		return ksz8795_change_mtu(dev, frame_size);
+	case KSZ8463_CHIP_ID:
 	case KSZ88X3_CHIP_ID:
 	case KSZ8864_CHIP_ID:
 	case KSZ8895_CHIP_ID:
@@ -1947,6 +1950,84 @@ u32 ksz8_get_port_addr(int port, int offset)
 	return PORT_CTRL_ADDR(port, offset);
 }
 
+u32 ksz8463_get_port_addr(int port, int offset)
+{
+	return offset + 0x18 * port;
+}
+
+static u16 ksz8463_get_phy_addr(u16 phy, u16 reg, u16 offset)
+{
+	return offset + reg * 2 + phy * (P2MBCR - P1MBCR);
+}
+
+int ksz8463_r_phy(struct ksz_device *dev, u16 phy, u16 reg, u16 *val)
+{
+	u16 sw_reg = 0;
+	u16 data = 0;
+	int ret;
+
+	if (phy > 1)
+		return -ENOSPC;
+	switch (reg) {
+	case MII_PHYSID1:
+		sw_reg = ksz8463_get_phy_addr(phy, 0, PHY1IHR);
+		break;
+	case MII_PHYSID2:
+		sw_reg = ksz8463_get_phy_addr(phy, 0, PHY1ILR);
+		break;
+	case MII_BMCR:
+	case MII_BMSR:
+	case MII_ADVERTISE:
+	case MII_LPA:
+		sw_reg = ksz8463_get_phy_addr(phy, reg, P1MBCR);
+		break;
+	case MII_TPISTATUS:
+		/* This register holds the PHY interrupt status for simulated
+		 * Micrel KSZ PHY.
+		 */
+		data = 0x0505;
+		break;
+	default:
+		break;
+	}
+	if (sw_reg) {
+		ret = ksz_read16(dev, sw_reg, &data);
+		if (ret)
+			return ret;
+	}
+	*val = data;
+
+	return 0;
+}
+
+int ksz8463_w_phy(struct ksz_device *dev, u16 phy, u16 reg, u16 val)
+{
+	u16 sw_reg = 0;
+	int ret;
+
+	if (phy > 1)
+		return -ENOSPC;
+
+	/* No write to fiber port. */
+	if (dev->ports[phy].fiber)
+		return 0;
+	switch (reg) {
+	case MII_BMCR:
+	case MII_ADVERTISE:
+		sw_reg = ksz8463_get_phy_addr(phy, reg, P1MBCR);
+		break;
+	default:
+		break;
+	}
+	if (sw_reg) {
+		ret = ksz_write16(dev, sw_reg, val);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
 int ksz8_switch_init(struct ksz_device *dev)
 {
 	dev->cpu_port = fls(dev->info->cpu_ports) - 1;