[PATCH v1 net-next] net: dsa: microchip: add KSZ9477 I2C driver

[<Tristram.Ha@microchip.com>]

From: Tristram Ha <Tristram.Ha@microchip.com>

Add KSZ9477 I2C driver support.  The code ksz9477.c and ksz_common.c are
used together to generate the I2C driver.

Signed-off-by: Tristram Ha <Tristram.Ha@microchip.com>
---
v1
- Return error code from i2c_transfer
- Change GPL license
- Change author

 drivers/net/dsa/microchip/Kconfig       |   6 +
 drivers/net/dsa/microchip/Makefile      |   1 +
 drivers/net/dsa/microchip/ksz9477_i2c.c | 196 ++++++++++++++++++++++++++++++++
 drivers/net/dsa/microchip/ksz_i2c.h     |  69 +++++++++++
 4 files changed, 272 insertions(+)
 create mode 100644 drivers/net/dsa/microchip/ksz9477_i2c.c
 create mode 100644 drivers/net/dsa/microchip/ksz_i2c.h

diff --git a/drivers/net/dsa/microchip/Kconfig b/drivers/net/dsa/microchip/Kconfig
index bea29fd..fd94441 100644
--- a/drivers/net/dsa/microchip/Kconfig
+++ b/drivers/net/dsa/microchip/Kconfig
@@ -9,6 +9,12 @@ menuconfig NET_DSA_MICROCHIP_KSZ9477
 	help
 	  This driver adds support for Microchip KSZ9477 switch chips.
 
+config NET_DSA_MICROCHIP_KSZ9477_I2C
+	tristate "KSZ9477 series I2C connected switch driver"
+	depends on NET_DSA_MICROCHIP_KSZ9477 && I2C
+	help
+	  Select to enable support for registering switches configured through I2C.
+
 config NET_DSA_MICROCHIP_KSZ9477_SPI
 	tristate "KSZ9477 series SPI connected switch driver"
 	depends on NET_DSA_MICROCHIP_KSZ9477 && SPI
diff --git a/drivers/net/dsa/microchip/Makefile b/drivers/net/dsa/microchip/Makefile
index 3142c18..dbcc5db 100644
--- a/drivers/net/dsa/microchip/Makefile
+++ b/drivers/net/dsa/microchip/Makefile
@@ -1,3 +1,4 @@
 obj-$(CONFIG_NET_DSA_MICROCHIP_KSZ_COMMON)	+= ksz_common.o
 obj-$(CONFIG_NET_DSA_MICROCHIP_KSZ9477)		+= ksz9477.o
+obj-$(CONFIG_NET_DSA_MICROCHIP_KSZ9477_I2C)	+= ksz9477_i2c.o
 obj-$(CONFIG_NET_DSA_MICROCHIP_KSZ9477_SPI)	+= ksz9477_spi.o
diff --git a/drivers/net/dsa/microchip/ksz9477_i2c.c b/drivers/net/dsa/microchip/ksz9477_i2c.c
new file mode 100644
index 0000000..29511e9
--- /dev/null
+++ b/drivers/net/dsa/microchip/ksz9477_i2c.c
@@ -0,0 +1,196 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Microchip KSZ9477 series register access through I2C
+ *
+ * Copyright (C) 2018 Microchip Technology Inc.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+
+#include "ksz_priv.h"
+#include "ksz_i2c.h"
+
+/* Enough to read all switch port registers. */
+#define I2C_TX_BUF_LEN			0x100
+
+static int ksz9477_i2c_read_reg(struct i2c_client *i2c, u32 reg, u8 *val,
+				unsigned int len)
+{
+	struct i2c_msg msg[2];
+	int ret;
+
+	val[0] = (u8)(reg >> 8);
+	val[1] = (u8)reg;
+
+	msg[0].addr = i2c->addr;
+	msg[0].flags = 0;
+	msg[0].len = 2;
+	msg[0].buf = val;
+
+	msg[1].addr = i2c->addr;
+	msg[1].flags = I2C_M_RD;
+	msg[1].len = len;
+	msg[1].buf = &val[2];
+
+	ret = i2c_transfer(i2c->adapter, msg, 2);
+	if (ret == 2)
+		ret = 0;
+	return ret;
+}
+
+static int ksz9477_i2c_write_reg(struct i2c_client *i2c, u32 reg, u8 *val,
+				 unsigned int len)
+{
+	struct i2c_msg msg;
+	int ret;
+
+	val[0] = (u8)(reg >> 8);
+	val[1] = (u8)reg;
+
+	msg.addr = i2c->addr;
+	msg.flags = 0;
+	msg.len = 2 + len;
+	msg.buf = val;
+
+	ret = i2c_transfer(i2c->adapter, &msg, 1);
+	if (ret == 1)
+		ret = 0;
+	return ret;
+}
+
+static int ksz_i2c_read(struct ksz_device *dev, u32 reg, u8 *data,
+			unsigned int len)
+{
+	struct i2c_client *i2c = dev->priv;
+	int ret;
+
+	ret = ksz9477_i2c_read_reg(i2c, reg, dev->txbuf, len);
+	if (!ret)
+		memcpy(data, &dev->txbuf[2], len);
+	return ret;
+}
+
+static int ksz_i2c_write(struct ksz_device *dev, u32 reg, void *data,
+			 unsigned int len)
+{
+	struct i2c_client *i2c = dev->priv;
+
+	if (len > I2C_TX_BUF_LEN)
+		len = I2C_TX_BUF_LEN;
+	memcpy(&dev->txbuf[2], data, len);
+	return ksz9477_i2c_write_reg(i2c, reg, dev->txbuf, len);
+}
+
+static int ksz_i2c_read24(struct ksz_device *dev, u32 reg, u32 *val)
+{
+	int ret;
+
+	*val = 0;
+	ret = ksz_i2c_read(dev, reg, (u8 *)val, 3);
+	if (!ret) {
+		*val = be32_to_cpu(*val);
+		/* convert to 24bit */
+		*val >>= 8;
+	}
+
+	return ret;
+}
+
+static int ksz_i2c_write24(struct ksz_device *dev, u32 reg, u32 value)
+{
+	/* make it to big endian 24bit from MSB */
+	value <<= 8;
+	value = cpu_to_be32(value);
+	return ksz_i2c_write(dev, reg, &value, 3);
+}
+
+static const struct ksz_io_ops ksz9477_i2c_ops = {
+	.read8 = ksz_i2c_read8,
+	.read16 = ksz_i2c_read16,
+	.read24 = ksz_i2c_read24,
+	.read32 = ksz_i2c_read32,
+	.write8 = ksz_i2c_write8,
+	.write16 = ksz_i2c_write16,
+	.write24 = ksz_i2c_write24,
+	.write32 = ksz_i2c_write32,
+	.get = ksz_i2c_get,
+	.set = ksz_i2c_set,
+};
+
+static int ksz9477_i2c_probe(struct i2c_client *i2c,
+			     const struct i2c_device_id *i2c_id)
+{
+	struct ksz_device *dev;
+	int ret;
+
+	dev = ksz_switch_alloc(&i2c->dev, &ksz9477_i2c_ops, i2c);
+	if (!dev)
+		return -ENOMEM;
+
+	if (i2c->dev.platform_data)
+		dev->pdata = i2c->dev.platform_data;
+
+	dev->txbuf = devm_kzalloc(dev->dev, 2 + I2C_TX_BUF_LEN, GFP_KERNEL);
+
+	ret = ksz9477_switch_register(dev);
+
+	/* Main DSA driver may not be started yet. */
+	if (ret)
+		return ret;
+
+	i2c_set_clientdata(i2c, dev);
+
+	return 0;
+}
+
+static int ksz9477_i2c_remove(struct i2c_client *i2c)
+{
+	struct ksz_device *dev = i2c_get_clientdata(i2c);
+
+	if (dev)
+		ksz_switch_remove(dev);
+
+	return 0;
+}
+
+static void ksz9477_i2c_shutdown(struct i2c_client *i2c)
+{
+	struct ksz_device *dev = i2c_get_clientdata(i2c);
+
+	if (dev && dev->dev_ops->shutdown)
+		dev->dev_ops->shutdown(dev);
+}
+
+static const struct i2c_device_id ksz9477_i2c_id[] = {
+	{ "ksz9477-switch", 0 },
+	{},
+};
+
+MODULE_DEVICE_TABLE(i2c, ksz9477_i2c_id);
+
+static const struct of_device_id ksz9477_dt_ids[] = {
+	{ .compatible = "microchip,ksz9477" },
+	{ .compatible = "microchip,ksz9897" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, ksz9477_dt_ids);
+
+static struct i2c_driver ksz9477_i2c_driver = {
+	.driver = {
+		.name	= "ksz9477-switch",
+		.owner	= THIS_MODULE,
+		.of_match_table = of_match_ptr(ksz9477_dt_ids),
+	},
+	.probe	= ksz9477_i2c_probe,
+	.remove	= ksz9477_i2c_remove,
+	.shutdown = ksz9477_i2c_shutdown,
+	.id_table = ksz9477_i2c_id,
+};
+
+module_i2c_driver(ksz9477_i2c_driver);
+
+MODULE_AUTHOR("Tristram Ha <Tristram.Ha@microchip.com>");
+MODULE_DESCRIPTION("Microchip KSZ9477 Series Switch I2C access Driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/net/dsa/microchip/ksz_i2c.h b/drivers/net/dsa/microchip/ksz_i2c.h
new file mode 100644
index 0000000..b9af0a8
--- /dev/null
+++ b/drivers/net/dsa/microchip/ksz_i2c.h
@@ -0,0 +1,69 @@
+/* SPDX-License-Identifier: GPL-2.0
+ * Microchip KSZ series I2C access common header
+ *
+ * Copyright (C) 2018 Microchip Technology Inc.
+ *	Tristram Ha <Tristram.Ha@microchip.com>
+ */
+
+#ifndef __KSZ_I2C_H
+#define __KSZ_I2C_H
+
+/* Chip dependent I2C access */
+static int ksz_i2c_read(struct ksz_device *dev, u32 reg, u8 *data,
+			unsigned int len);
+static int ksz_i2c_write(struct ksz_device *dev, u32 reg, void *data,
+			 unsigned int len);
+
+static int ksz_i2c_read8(struct ksz_device *dev, u32 reg, u8 *val)
+{
+	return ksz_i2c_read(dev, reg, val, 1);
+}
+
+static int ksz_i2c_read16(struct ksz_device *dev, u32 reg, u16 *val)
+{
+	int ret = ksz_i2c_read(dev, reg, (u8 *)val, 2);
+
+	if (!ret)
+		*val = be16_to_cpu(*val);
+
+	return ret;
+}
+
+static int ksz_i2c_read32(struct ksz_device *dev, u32 reg, u32 *val)
+{
+	int ret = ksz_i2c_read(dev, reg, (u8 *)val, 4);
+
+	if (!ret)
+		*val = be32_to_cpu(*val);
+
+	return ret;
+}
+
+static int ksz_i2c_write8(struct ksz_device *dev, u32 reg, u8 value)
+{
+	return ksz_i2c_write(dev, reg, &value, 1);
+}
+
+static int ksz_i2c_write16(struct ksz_device *dev, u32 reg, u16 value)
+{
+	value = cpu_to_be16(value);
+	return ksz_i2c_write(dev, reg, &value, 2);
+}
+
+static int ksz_i2c_write32(struct ksz_device *dev, u32 reg, u32 value)
+{
+	value = cpu_to_be32(value);
+	return ksz_i2c_write(dev, reg, &value, 4);
+}
+
+static int ksz_i2c_get(struct ksz_device *dev, u32 reg, void *data, size_t len)
+{
+	return ksz_i2c_read(dev, reg, data, len);
+}
+
+static int ksz_i2c_set(struct ksz_device *dev, u32 reg, void *data, size_t len)
+{
+	return ksz_i2c_write(dev, reg, data, len);
+}
+
+#endif
-- 
1.9.1