net: dsa: mv88e6xxx: refine SMI support

The Marvell SOHO switches have several ways to access the internal
registers. One of them being the System Management Interface (SMI),
using the MDC and MDIO pins, with direct and indirect variants.

In preparation for adding support for other register accesses, move
the SMI code into its own files. At the same time, refine the code
to make it clear that the indirect variant is implemented using the
direct variant accessing only two registers for command and data.

Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index bad30be..28414db 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -43,6 +43,7 @@
 #include "port.h"
 #include "ptp.h"
 #include "serdes.h"
+#include "smi.h"
 
 static void assert_reg_lock(struct mv88e6xxx_chip *chip)
 {
@@ -52,149 +53,6 @@ static void assert_reg_lock(struct mv88e6xxx_chip *chip)
 	}
 }
 
-/* The switch ADDR[4:1] configuration pins define the chip SMI device address
- * (ADDR[0] is always zero, thus only even SMI addresses can be strapped).
- *
- * When ADDR is all zero, the chip uses Single-chip Addressing Mode, assuming it
- * is the only device connected to the SMI master. In this mode it responds to
- * all 32 possible SMI addresses, and thus maps directly the internal devices.
- *
- * When ADDR is non-zero, the chip uses Multi-chip Addressing Mode, allowing
- * multiple devices to share the SMI interface. In this mode it responds to only
- * 2 registers, used to indirectly access the internal SMI devices.
- */
-
-static int mv88e6xxx_smi_read(struct mv88e6xxx_chip *chip,
-			      int addr, int reg, u16 *val)
-{
-	if (!chip->smi_ops)
-		return -EOPNOTSUPP;
-
-	return chip->smi_ops->read(chip, addr, reg, val);
-}
-
-static int mv88e6xxx_smi_write(struct mv88e6xxx_chip *chip,
-			       int addr, int reg, u16 val)
-{
-	if (!chip->smi_ops)
-		return -EOPNOTSUPP;
-
-	return chip->smi_ops->write(chip, addr, reg, val);
-}
-
-static int mv88e6xxx_smi_single_chip_read(struct mv88e6xxx_chip *chip,
-					  int addr, int reg, u16 *val)
-{
-	int ret;
-
-	ret = mdiobus_read_nested(chip->bus, addr, reg);
-	if (ret < 0)
-		return ret;
-
-	*val = ret & 0xffff;
-
-	return 0;
-}
-
-static int mv88e6xxx_smi_single_chip_write(struct mv88e6xxx_chip *chip,
-					   int addr, int reg, u16 val)
-{
-	int ret;
-
-	ret = mdiobus_write_nested(chip->bus, addr, reg, val);
-	if (ret < 0)
-		return ret;
-
-	return 0;
-}
-
-static const struct mv88e6xxx_bus_ops mv88e6xxx_smi_single_chip_ops = {
-	.read = mv88e6xxx_smi_single_chip_read,
-	.write = mv88e6xxx_smi_single_chip_write,
-};
-
-static int mv88e6xxx_smi_multi_chip_wait(struct mv88e6xxx_chip *chip)
-{
-	int ret;
-	int i;
-
-	for (i = 0; i < 16; i++) {
-		ret = mdiobus_read_nested(chip->bus, chip->sw_addr, SMI_CMD);
-		if (ret < 0)
-			return ret;
-
-		if ((ret & SMI_CMD_BUSY) == 0)
-			return 0;
-	}
-
-	return -ETIMEDOUT;
-}
-
-static int mv88e6xxx_smi_multi_chip_read(struct mv88e6xxx_chip *chip,
-					 int addr, int reg, u16 *val)
-{
-	int ret;
-
-	/* Wait for the bus to become free. */
-	ret = mv88e6xxx_smi_multi_chip_wait(chip);
-	if (ret < 0)
-		return ret;
-
-	/* Transmit the read command. */
-	ret = mdiobus_write_nested(chip->bus, chip->sw_addr, SMI_CMD,
-				   SMI_CMD_OP_22_READ | (addr << 5) | reg);
-	if (ret < 0)
-		return ret;
-
-	/* Wait for the read command to complete. */
-	ret = mv88e6xxx_smi_multi_chip_wait(chip);
-	if (ret < 0)
-		return ret;
-
-	/* Read the data. */
-	ret = mdiobus_read_nested(chip->bus, chip->sw_addr, SMI_DATA);
-	if (ret < 0)
-		return ret;
-
-	*val = ret & 0xffff;
-
-	return 0;
-}
-
-static int mv88e6xxx_smi_multi_chip_write(struct mv88e6xxx_chip *chip,
-					  int addr, int reg, u16 val)
-{
-	int ret;
-
-	/* Wait for the bus to become free. */
-	ret = mv88e6xxx_smi_multi_chip_wait(chip);
-	if (ret < 0)
-		return ret;
-
-	/* Transmit the data to write. */
-	ret = mdiobus_write_nested(chip->bus, chip->sw_addr, SMI_DATA, val);
-	if (ret < 0)
-		return ret;
-
-	/* Transmit the write command. */
-	ret = mdiobus_write_nested(chip->bus, chip->sw_addr, SMI_CMD,
-				   SMI_CMD_OP_22_WRITE | (addr << 5) | reg);
-	if (ret < 0)
-		return ret;
-
-	/* Wait for the write command to complete. */
-	ret = mv88e6xxx_smi_multi_chip_wait(chip);
-	if (ret < 0)
-		return ret;
-
-	return 0;
-}
-
-static const struct mv88e6xxx_bus_ops mv88e6xxx_smi_multi_chip_ops = {
-	.read = mv88e6xxx_smi_multi_chip_read,
-	.write = mv88e6xxx_smi_multi_chip_write,
-};
-
 int mv88e6xxx_read(struct mv88e6xxx_chip *chip, int addr, int reg, u16 *val)
 {
 	int err;
@@ -4645,22 +4503,6 @@ static struct mv88e6xxx_chip *mv88e6xxx_alloc_chip(struct device *dev)
 	return chip;
 }
 
-static int mv88e6xxx_smi_init(struct mv88e6xxx_chip *chip,
-			      struct mii_bus *bus, int sw_addr)
-{
-	if (sw_addr == 0)
-		chip->smi_ops = &mv88e6xxx_smi_single_chip_ops;
-	else if (chip->info->multi_chip)
-		chip->smi_ops = &mv88e6xxx_smi_multi_chip_ops;
-	else
-		return -EINVAL;
-
-	chip->bus = bus;
-	chip->sw_addr = sw_addr;
-
-	return 0;
-}
-
 static enum dsa_tag_protocol mv88e6xxx_get_tag_protocol(struct dsa_switch *ds,
 							int port)
 {