net: dsa: microchip: Add Microchip KSZ8863 SMI based driver support

Add KSZ88X3 driver support. We add support for the KXZ88X3 three port
switches using the Microchip SMI Interface. They are supported using the
MDIO-Bitbang Interface.
Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/microchip/Kconfig

@@ -29,7 +29,7 @@ menuconfig NET_DSA_MICROCHIP_KSZ8795
 	depends on NET_DSA
 	select NET_DSA_MICROCHIP_KSZ_COMMON
 	help
-	  This driver adds support for Microchip KSZ8795 switch chips.
+	  This driver adds support for Microchip KSZ8795/KSZ88X3 switch chips.
 
 config NET_DSA_MICROCHIP_KSZ8795_SPI
 	tristate "KSZ8795 series SPI connected switch driver"
@@ -40,3 +40,11 @@ config NET_DSA_MICROCHIP_KSZ8795_SPI
 
 	  It is required to use the KSZ8795 switch driver as the only access
 	  is through SPI.
+
+config NET_DSA_MICROCHIP_KSZ8863_SMI
+	tristate "KSZ series SMI connected switch driver"
+	depends on NET_DSA_MICROCHIP_KSZ8795
+	select MDIO_BITBANG
+	help
+	  Select to enable support for registering switches configured through
+	  Microchip SMI. It supports the KSZ8863 and KSZ8873 switch.

drivers/net/dsa/microchip/Makefile

@@ -5,3 +5,4 @@ obj-$(CONFIG_NET_DSA_MICROCHIP_KSZ9477_I2C)	+= ksz9477_i2c.o
 obj-$(CONFIG_NET_DSA_MICROCHIP_KSZ9477_SPI)	+= ksz9477_spi.o
 obj-$(CONFIG_NET_DSA_MICROCHIP_KSZ8795)		+= ksz8795.o
 obj-$(CONFIG_NET_DSA_MICROCHIP_KSZ8795_SPI)	+= ksz8795_spi.o
+obj-$(CONFIG_NET_DSA_MICROCHIP_KSZ8863_SMI)	+= ksz8863_smi.o

drivers/net/dsa/microchip/ksz8863_smi.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Microchip KSZ8863 series register access through SMI
+ *
+ * Copyright (C) 2019 Pengutronix, Michael Grzeschik <kernel@pengutronix.de>
+ */
+
+#include "ksz8.h"
+#include "ksz_common.h"
+
+/* Serial Management Interface (SMI) uses the following frame format:
+ *
+ *       preamble|start|Read/Write|  PHY   |  REG  |TA|   Data bits      | Idle
+ *               |frame| OP code  |address |address|  |                  |
+ * read | 32x1´s | 01  |    00    | 1xRRR  | RRRRR |Z0| 00000000DDDDDDDD |  Z
+ * write| 32x1´s | 01  |    00    | 0xRRR  | RRRRR |10| xxxxxxxxDDDDDDDD |  Z
+ *
+ */
+
+#define SMI_KSZ88XX_READ_PHY	BIT(4)
+
+static int ksz8863_mdio_read(void *ctx, const void *reg_buf, size_t reg_len,
+			     void *val_buf, size_t val_len)
+{
+	struct ksz_device *dev = ctx;
+	struct mdio_device *mdev;
+	u8 reg = *(u8 *)reg_buf;
+	u8 *val = val_buf;
+	struct ksz8 *ksz8;
+	int i, ret = 0;
+
+	ksz8 = dev->priv;
+	mdev = ksz8->priv;
+
+	mutex_lock_nested(&mdev->bus->mdio_lock, MDIO_MUTEX_NESTED);
+	for (i = 0; i < val_len; i++) {
+		int tmp = reg + i;
+
+		ret = __mdiobus_read(mdev->bus, ((tmp & 0xE0) >> 5) |
+				     SMI_KSZ88XX_READ_PHY, tmp);
+		if (ret < 0)
+			goto out;
+
+		val[i] = ret;
+	}
+	ret = 0;
+
+ out:
+	mutex_unlock(&mdev->bus->mdio_lock);
+
+	return ret;
+}
+
+static int ksz8863_mdio_write(void *ctx, const void *data, size_t count)
+{
+	struct ksz_device *dev = ctx;
+	struct mdio_device *mdev;
+	struct ksz8 *ksz8;
+	int i, ret = 0;
+	u32 reg;
+	u8 *val;
+
+	ksz8 = dev->priv;
+	mdev = ksz8->priv;
+
+	val = (u8 *)(data + 4);
+	reg = *(u32 *)data;
+
+	mutex_lock_nested(&mdev->bus->mdio_lock, MDIO_MUTEX_NESTED);
+	for (i = 0; i < (count - 4); i++) {
+		int tmp = reg + i;
+
+		ret = __mdiobus_write(mdev->bus, ((tmp & 0xE0) >> 5),
+				      tmp, val[i]);
+		if (ret < 0)
+			goto out;
+	}
+
+ out:
+	mutex_unlock(&mdev->bus->mdio_lock);
+
+	return ret;
+}
+
+static const struct regmap_bus regmap_smi[] = {
+	{
+		.read = ksz8863_mdio_read,
+		.write = ksz8863_mdio_write,
+		.max_raw_read = 1,
+		.max_raw_write = 1,
+	},
+	{
+		.read = ksz8863_mdio_read,
+		.write = ksz8863_mdio_write,
+		.val_format_endian_default = REGMAP_ENDIAN_BIG,
+		.max_raw_read = 2,
+		.max_raw_write = 2,
+	},
+	{
+		.read = ksz8863_mdio_read,
+		.write = ksz8863_mdio_write,
+		.val_format_endian_default = REGMAP_ENDIAN_BIG,
+		.max_raw_read = 4,
+		.max_raw_write = 4,
+	}
+};
+
+static const struct regmap_config ksz8863_regmap_config[] = {
+	{
+		.name = "#8",
+		.reg_bits = 8,
+		.pad_bits = 24,
+		.val_bits = 8,
+		.cache_type = REGCACHE_NONE,
+		.use_single_read = 1,
+		.lock = ksz_regmap_lock,
+		.unlock = ksz_regmap_unlock,
+	},
+	{
+		.name = "#16",
+		.reg_bits = 8,
+		.pad_bits = 24,
+		.val_bits = 16,
+		.cache_type = REGCACHE_NONE,
+		.use_single_read = 1,
+		.lock = ksz_regmap_lock,
+		.unlock = ksz_regmap_unlock,
+	},
+	{
+		.name = "#32",
+		.reg_bits = 8,
+		.pad_bits = 24,
+		.val_bits = 32,
+		.cache_type = REGCACHE_NONE,
+		.use_single_read = 1,
+		.lock = ksz_regmap_lock,
+		.unlock = ksz_regmap_unlock,
+	}
+};
+
+static int ksz8863_smi_probe(struct mdio_device *mdiodev)
+{
+	struct regmap_config rc;
+	struct ksz_device *dev;
+	struct ksz8 *ksz8;
+	int ret;
+	int i;
+
+	ksz8 = devm_kzalloc(&mdiodev->dev, sizeof(struct ksz8), GFP_KERNEL);
+	ksz8->priv = mdiodev;
+
+	dev = ksz_switch_alloc(&mdiodev->dev, ksz8);
+	if (!dev)
+		return -EINVAL;
+
+	for (i = 0; i < ARRAY_SIZE(ksz8863_regmap_config); i++) {
+		rc = ksz8863_regmap_config[i];
+		rc.lock_arg = &dev->regmap_mutex;
+		dev->regmap[i] = devm_regmap_init(&mdiodev->dev,
+						  &regmap_smi[i], dev,
+						  &rc);
+		if (IS_ERR(dev->regmap[i])) {
+			ret = PTR_ERR(dev->regmap[i]);
+			dev_err(&mdiodev->dev,
+				"Failed to initialize regmap%i: %d\n",
+				ksz8863_regmap_config[i].val_bits, ret);
+			return ret;
+		}
+	}
+
+	if (mdiodev->dev.platform_data)
+		dev->pdata = mdiodev->dev.platform_data;
+
+	ret = ksz8_switch_register(dev);
+
+	/* Main DSA driver may not be started yet. */
+	if (ret)
+		return ret;
+
+	dev_set_drvdata(&mdiodev->dev, dev);
+
+	return 0;
+}
+
+static void ksz8863_smi_remove(struct mdio_device *mdiodev)
+{
+	struct ksz_device *dev = dev_get_drvdata(&mdiodev->dev);
+
+	if (dev)
+		ksz_switch_remove(dev);
+}
+
+static const struct of_device_id ksz8863_dt_ids[] = {
+	{ .compatible = "microchip,ksz8863" },
+	{ .compatible = "microchip,ksz8873" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, ksz8863_dt_ids);
+
+static struct mdio_driver ksz8863_driver = {
+	.probe	= ksz8863_smi_probe,
+	.remove	= ksz8863_smi_remove,
+	.mdiodrv.driver = {
+		.name	= "ksz8863-switch",
+		.of_match_table = ksz8863_dt_ids,
+	},
+};
+
+mdio_module_driver(ksz8863_driver);
+
+MODULE_AUTHOR("Michael Grzeschik <m.grzeschik@pengutronix.de>");
+MODULE_DESCRIPTION("Microchip KSZ8863 SMI Switch driver");
+MODULE_LICENSE("GPL v2");