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 <[email protected]>
Reviewed-by: Andrew Lunn <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

1 files changed, 104 insertions, 0 deletions

diff --git a/drivers/net/dsa/microchip/ksz_spi.c b/drivers/net/dsa/microchip/ksz_spi.c
index b633d263098c..d8001734b057 100644
--- a/drivers/net/dsa/microchip/ksz_spi.c
+++ b/drivers/net/dsa/microchip/ksz_spi.c
@@ -16,6 +16,10 @@
 
 #include "ksz_common.h"
 
+#define KSZ8463_SPI_ADDR_SHIFT			13
+#define KSZ8463_SPI_ADDR_ALIGN			3
+#define KSZ8463_SPI_TURNAROUND_SHIFT		2
+
 #define KSZ8795_SPI_ADDR_SHIFT			12
 #define KSZ8795_SPI_ADDR_ALIGN			3
 #define KSZ8795_SPI_TURNAROUND_SHIFT		1
@@ -37,6 +41,99 @@ KSZ_REGMAP_TABLE(ksz8863, 16, KSZ8863_SPI_ADDR_SHIFT,
 KSZ_REGMAP_TABLE(ksz9477, 32, KSZ9477_SPI_ADDR_SHIFT,
 		 KSZ9477_SPI_TURNAROUND_SHIFT, KSZ9477_SPI_ADDR_ALIGN);
 
+static u16 ksz8463_reg(u16 reg, size_t size)
+{
+	switch (size) {
+	case 1:
+		reg = ((reg >> 2) << 4) | (1 << (reg & 3));
+		break;
+	case 2:
+		reg = ((reg >> 2) << 4) | (reg & 2 ? 0x0c : 0x03);
+		break;
+	default:
+		reg = ((reg >> 2) << 4) | 0xf;
+		break;
+	}
+	reg <<= KSZ8463_SPI_TURNAROUND_SHIFT;
+	return reg;
+}
+
+static int ksz8463_spi_read(void *context,
+			    const void *reg, size_t reg_size,
+			    void *val, size_t val_size)
+{
+	struct device *dev = context;
+	struct spi_device *spi = to_spi_device(dev);
+	u8 bytes[2];
+	u16 cmd;
+	int rc;
+
+	if (reg_size > 2 || val_size > 4)
+		return -EINVAL;
+	memcpy(&cmd, reg, sizeof(u16));
+	cmd = ksz8463_reg(cmd, val_size);
+	/* SPI command uses big-endian format. */
+	put_unaligned_be16(cmd, bytes);
+	rc = spi_write_then_read(spi, bytes, reg_size, val, val_size);
+#if defined(__BIG_ENDIAN)
+	/* Register value uses little-endian format so need to convert when
+	 * running in big-endian system.
+	 */
+	if (!rc && val_size > 1) {
+		if (val_size == 2) {
+			u16 v = get_unaligned_le16(val);
+
+			memcpy(val, &v, sizeof(v));
+		} else if (val_size == 4) {
+			u32 v = get_unaligned_le32(val);
+
+			memcpy(val, &v, sizeof(v));
+		}
+	}
+#endif
+	return rc;
+}
+
+static int ksz8463_spi_write(void *context, const void *data, size_t count)
+{
+	struct device *dev = context;
+	struct spi_device *spi = to_spi_device(dev);
+	size_t val_size = count - 2;
+	u8 bytes[6];
+	u16 cmd;
+
+	if (count <= 2 || count > 6)
+		return -EINVAL;
+	memcpy(bytes, data, count);
+	memcpy(&cmd, data, sizeof(u16));
+	cmd = ksz8463_reg(cmd, val_size);
+	cmd |= (1 << (KSZ8463_SPI_ADDR_SHIFT + KSZ8463_SPI_TURNAROUND_SHIFT));
+	/* SPI command uses big-endian format. */
+	put_unaligned_be16(cmd, bytes);
+#if defined(__BIG_ENDIAN)
+	/* Register value uses little-endian format so need to convert when
+	 * running in big-endian system.
+	 */
+	if (val_size == 2) {
+		u8 *val = &bytes[2];
+		u16 v;
+
+		memcpy(&v, val, sizeof(v));
+		put_unaligned_le16(v, val);
+	} else if (val_size == 4) {
+		u8 *val = &bytes[2];
+		u32 v;
+
+		memcpy(&v, val, sizeof(v));
+		put_unaligned_le32(v, val);
+	}
+#endif
+	return spi_write(spi, bytes, count);
+}
+
+KSZ8463_REGMAP_TABLE(ksz8463, KSZ8463_SPI_ADDR_SHIFT, 0,
+		     KSZ8463_SPI_ADDR_ALIGN);
+
 static int ksz_spi_probe(struct spi_device *spi)
 {
 	const struct regmap_config *regmap_config;
@@ -58,6 +155,8 @@ static int ksz_spi_probe(struct spi_device *spi)
 	dev->chip_id = chip->chip_id;
 	if (chip->chip_id == KSZ88X3_CHIP_ID)
 		regmap_config = ksz8863_regmap_config;
+	else if (chip->chip_id == KSZ8463_CHIP_ID)
+		regmap_config = ksz8463_regmap_config;
 	else if (chip->chip_id == KSZ8795_CHIP_ID ||
 		 chip->chip_id == KSZ8794_CHIP_ID ||
 		 chip->chip_id == KSZ8765_CHIP_ID)
@@ -126,6 +225,10 @@ static void ksz_spi_shutdown(struct spi_device *spi)
 
 static const struct of_device_id ksz_dt_ids[] = {
 	{
+		.compatible = "microchip,ksz8463",
+		.data = &ksz_switch_chips[KSZ8463]
+	},
+	{
 		.compatible = "microchip,ksz8765",
 		.data = &ksz_switch_chips[KSZ8765]
 	},
@@ -214,6 +317,7 @@ static const struct of_device_id ksz_dt_ids[] = {
 MODULE_DEVICE_TABLE(of, ksz_dt_ids);
 
 static const struct spi_device_id ksz_spi_ids[] = {
+	{ "ksz8463" },
 	{ "ksz8765" },
 	{ "ksz8794" },
 	{ "ksz8795" },