Re: [PATCH v4 09/11] 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 <redacted>

---
v1 -> v2:  - this code was part of previuos patch
v2 -> v3:  - this code was part of previuos patch
v3 -> v4:  - moved this glue code so separate patch
           - fixed locking in regmap and mdio_read/mdio_write

 drivers/net/dsa/microchip/Kconfig       |   9 ++
 drivers/net/dsa/microchip/Makefile      |   1 +
 drivers/net/dsa/microchip/ksz8863_smi.c | 204
++++++++++++++++++++++++
 3 files changed, 214 insertions(+)
 create mode 100644 drivers/net/dsa/microchip/ksz8863_smi.c

diff --git a/drivers/net/dsa/microchip/Kconfig

b/drivers/net/dsa/microchip/Kconfig
index 4ec6a47b7f7284f..c5819bd4121cc7c 100644

--- a/drivers/net/dsa/microchip/Kconfig
+++ b/drivers/net/dsa/microchip/Kconfig

@@ -40,3 +40,12 @@ 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
+	default y
+	help
+	  Select to enable support for registering switches configured
through
+	  Microchip SMI. It Supports the KSZ8863 and KSZ8873 Switch.

diff --git a/drivers/net/dsa/microchip/Makefile

b/drivers/net/dsa/microchip/Makefile
index 929caa81e782ed2..2a03b21a3386f5d 100644

--- a/drivers/net/dsa/microchip/Makefile
+++ b/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

diff --git a/drivers/net/dsa/microchip/ksz8863_smi.c

b/drivers/net/dsa/microchip/ksz8863_smi.c
new file mode 100644
index 000000000000000..fd493441d725284

--- /dev/null
+++ b/drivers/net/dsa/microchip/ksz8863_smi.c

@@ -0,0 +1,204 @@
+// 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
+ *
+ */
+
+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 = (struct ksz_device *)ctx;
+	struct ksz8 *ksz8 = dev->priv;
+	struct mdio_device *mdev = ksz8->priv;
+	u8 reg = *(u8 *)reg_buf;
+	u8 *val = val_buf;
+	int ret = 0;
+	int i;
+
+	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) |
+				     BIT(4), 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 = (struct ksz_device *)ctx;
+	struct ksz8 *ksz8 = dev->priv;
+	struct mdio_device *mdev = ksz8->priv;
+	u8 *val = (u8 *)(data + 4);
+	u32 reg = *(u32 *)data;
+	int ret = 0;
+	int i;
+
+	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 [off-list ref]");
+MODULE_DESCRIPTION("Microchip KSZ8863 SMI Switch driver");
+MODULE_LICENSE("GPL v2");