net: dsa: microchip: break KSZ9477 DSA driver into two files

Break KSZ9477 DSA driver into two files in preparation to add more KSZ
switch drivers.
Add common functions in ksz_common.h so that other KSZ switch drivers
can access code in ksz_common.c.
Add ksz_spi.h for common functions used by KSZ switch SPI drivers.

Signed-off-by: Tristram Ha <Tristram.Ha@microchip.com>
Reviewed-by: Woojung Huh <Woojung.Huh@microchip.com>
Reviewed-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/microchip/ksz_spi.h

@@ -0,0 +1,69 @@
+/* SPDX-License-Identifier: GPL-2.0
+ * Microchip KSZ series SPI access common header
+ *
+ * Copyright (C) 2017-2018 Microchip Technology Inc.
+ *	Tristram Ha <Tristram.Ha@microchip.com>
+ */
+
+#ifndef __KSZ_SPI_H
+#define __KSZ_SPI_H
+
+/* Chip dependent SPI access */
+static int ksz_spi_read(struct ksz_device *dev, u32 reg, u8 *data,
+			unsigned int len);
+static int ksz_spi_write(struct ksz_device *dev, u32 reg, void *data,
+			 unsigned int len);
+
+static int ksz_spi_read8(struct ksz_device *dev, u32 reg, u8 *val)
+{
+	return ksz_spi_read(dev, reg, val, 1);
+}
+
+static int ksz_spi_read16(struct ksz_device *dev, u32 reg, u16 *val)
+{
+	int ret = ksz_spi_read(dev, reg, (u8 *)val, 2);
+
+	if (!ret)
+		*val = be16_to_cpu(*val);
+
+	return ret;
+}
+
+static int ksz_spi_read32(struct ksz_device *dev, u32 reg, u32 *val)
+{
+	int ret = ksz_spi_read(dev, reg, (u8 *)val, 4);
+
+	if (!ret)
+		*val = be32_to_cpu(*val);
+
+	return ret;
+}
+
+static int ksz_spi_write8(struct ksz_device *dev, u32 reg, u8 value)
+{
+	return ksz_spi_write(dev, reg, &value, 1);
+}
+
+static int ksz_spi_write16(struct ksz_device *dev, u32 reg, u16 value)
+{
+	value = cpu_to_be16(value);
+	return ksz_spi_write(dev, reg, &value, 2);
+}
+
+static int ksz_spi_write32(struct ksz_device *dev, u32 reg, u32 value)
+{
+	value = cpu_to_be32(value);
+	return ksz_spi_write(dev, reg, &value, 4);
+}
+
+static int ksz_spi_get(struct ksz_device *dev, u32 reg, void *data, size_t len)
+{
+	return ksz_spi_read(dev, reg, data, len);
+}
+
+static int ksz_spi_set(struct ksz_device *dev, u32 reg, void *data, size_t len)
+{
+	return ksz_spi_write(dev, reg, data, len);
+}
+
+#endif