[PATCH v2 2/3] i2c: add support for Cypress CYUSBS234 USB-I2C adapter

[Muthu Mani]

Adds support for USB-I2C interface of Cypress Semiconductor
CYUSBS234 USB-Serial Bridge controller.

The read/write operation is setup using vendor command through control endpoint
and actual data transfer happens through bulk in/out endpoints.

Details about the device can be found at:
http://www.cypress.com/?rID=84126

Signed-off-by: Muthu Mani <muth@xxxxxxxxxxx>
Signed-off-by: Rajaram Regupathy <rera@xxxxxxxxxxx>
---
 drivers/i2c/busses/Kconfig         |  12 +
 drivers/i2c/busses/Makefile        |   1 +
 drivers/i2c/busses/i2c-cyusbs23x.c | 514 +++++++++++++++++++++++++++++++++++++
 3 files changed, 527 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-cyusbs23x.c

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 2ac87fa..1fdc6ec 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -848,6 +848,18 @@ config I2C_RCAR
 
 comment "External I2C/SMBus adapter drivers"
 
+config I2C_CYUSBS23X
+        tristate "CYUSBS23x I2C adapter"
+        depends on MFD_CYUSBS23X && USB
+        help
+	  Say yes if you would like to access Cypress CYUSBS23x I2C device.
+
+	  This driver enables the I2C interface of CYUSBS23x USB Serial Bridge
+	  controller.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called i2c-cyusbs23x.
+
 config I2C_DIOLAN_U2C
 	tristate "Diolan U2C-12 USB adapter"
 	depends on USB
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 49bf07e..cbf28cb 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -84,6 +84,7 @@ obj-$(CONFIG_I2C_XLR)		+= i2c-xlr.o
 obj-$(CONFIG_I2C_RCAR)		+= i2c-rcar.o
 
 # External I2C/SMBus adapter drivers
+obj-$(CONFIG_I2C_CYUSBS23X)	+= i2c-cyusbs23x.o
 obj-$(CONFIG_I2C_DIOLAN_U2C)	+= i2c-diolan-u2c.o
 obj-$(CONFIG_I2C_PARPORT)	+= i2c-parport.o
 obj-$(CONFIG_I2C_PARPORT_LIGHT)	+= i2c-parport-light.o
diff --git a/drivers/i2c/busses/i2c-cyusbs23x.c b/drivers/i2c/busses/i2c-cyusbs23x.c
new file mode 100644
index 0000000..5cf60f0
--- /dev/null
+++ b/drivers/i2c/busses/i2c-cyusbs23x.c
@@ -0,0 +1,514 @@
+/*
+ * I2C subdriver for Cypress CYUSBS234 USB-Serial Bridge controller.
+ * Details about the device can be found at:
+ *    http://www.cypress.com/?rID=84126
+ *
+ * Copyright (c) 2014 Cypress Semiconductor Corporation.
+ *
+ * Author:
+ *   Rajaram Regupathy <rera@xxxxxxxxxxx>
+ *
+ * Additional contributors include:
+ *   Muthu Mani <muth@xxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+/*
+ * It exposes sysfs entries under the i2c adapter for getting the i2c transfer
+ * status, reset i2c read/write module, get/set nak and stop bits.
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+
+#include <linux/usb.h>
+#include <linux/i2c.h>
+
+#include <linux/mfd/cyusbs23x.h>
+
+#define CY_I2C_MODE_WRITE          1
+#define CY_I2C_MODE_READ           0
+
+#define CY_I2C_XFER_STATUS_LEN     3
+
+struct cyusbs_i2c_config {
+	u32 frequency;        /* Frequency of operation. Only valid values are
+				 100KHz and 400KHz */
+	u8 slave_addr;        /* Slave address to be used when in slave mode */
+	u8 is_msb_first;      /* Whether to transmit MSB first */
+	u8 is_master;         /* Whether block is to be configured as a master:
+				 1 - The block functions as I2C master;
+				 0 - The block functions as I2C slave */
+	u8 s_ignore;          /* Ignore general call in slave mode */
+	u8 clock_stretch;     /* Whether to stretch clock in case of no FIFO
+				 availability */
+	u8 is_loopback;       /* Whether to loop back TX data to RX. Valid
+				 only for debug purposes */
+	u8 reserved[6];       /* Reserved for future use */
+} __packed;
+
+struct cyusbs_i2c {
+	struct i2c_adapter i2c_adapter;
+	struct cyusbs_i2c_config *i2c_config;
+
+	bool is_stop_bit;
+	bool is_nak_bit;
+};
+
+#define to_cyusbs_i2c(a) container_of(a, struct cyusbs_i2c, i2c_adapter)
+
+static int cy_i2c_get_status(struct device *d, char *buf, u16 mode);
+static int cy_i2c_reset(struct device *d, u16 mode);
+
+static ssize_t i2c_read_status_show(struct device *d,
+				    struct device_attribute *attr, char *buf)
+{
+	dev_dbg(d, "%s\n", __func__);
+	return cy_i2c_get_status(d, buf, CY_I2C_MODE_READ);
+}
+
+static ssize_t i2c_write_status_show(struct device *d,
+				     struct device_attribute *attr, char *buf)
+{
+	dev_dbg(d, "%s\n", __func__);
+	return cy_i2c_get_status(d, buf, CY_I2C_MODE_WRITE);
+}
+
+static ssize_t i2c_read_reset_store(struct device *d,
+				 struct device_attribute *attr,
+				 const char *buf, size_t count)
+{
+	int ret;
+
+	if (((count != 1) && (count != 2 || buf[1] != '\n')) || (buf[0] != '1'))
+		return -EINVAL;
+
+	dev_dbg(d, "%s\n", __func__);
+	ret = cy_i2c_reset(d, CY_I2C_MODE_READ);
+
+	if (!ret)
+		ret = count;
+
+	return ret;
+}
+
+static ssize_t i2c_write_reset_store(struct device *d,
+				  struct device_attribute *attr,
+				  const char *buf, size_t count)
+{
+	int ret;
+
+	if (((count != 1) && (count != 2 || buf[1] != '\n')) || (buf[0] != '1'))
+		return -EINVAL;
+
+	dev_dbg(d, "%s\n", __func__);
+	ret = cy_i2c_reset(d, CY_I2C_MODE_WRITE);
+
+	if (!ret)
+		ret = count;
+
+	return ret;
+}
+
+static ssize_t is_stop_bit_show(struct device *d,
+				struct device_attribute *attr, char *buf)
+{
+	struct i2c_adapter *adapter = to_i2c_adapter(d);
+	struct cyusbs_i2c *cy_i2c = to_cyusbs_i2c(adapter);
+
+	return sprintf(buf, "%d\n", cy_i2c->is_stop_bit);
+}
+
+static ssize_t is_stop_bit_store(struct device *d,
+				 struct device_attribute *attr,
+				 const char *buf, size_t count)
+{
+	struct i2c_adapter *adapter = to_i2c_adapter(d);
+	struct cyusbs_i2c *cy_i2c = to_cyusbs_i2c(adapter);
+
+	if ((count != 1) && (count != 2 || buf[1] != '\n'))
+		return -EINVAL;
+
+	if (buf[0] == '0')
+		cy_i2c->is_stop_bit = 0;
+	else if (buf[0] == '1')
+		cy_i2c->is_stop_bit = 1;
+	else
+		return -EINVAL;
+
+	dev_dbg(d, "is_stop_bit=%d buf=%s\n", cy_i2c->is_stop_bit, buf);
+
+	return count;
+}
+
+static ssize_t is_nak_bit_show(struct device *d,
+			       struct device_attribute *attr, char *buf)
+{
+	struct i2c_adapter *adapter = to_i2c_adapter(d);
+	struct cyusbs_i2c *cy_i2c = to_cyusbs_i2c(adapter);
+
+	return sprintf(buf, "%d\n", cy_i2c->is_nak_bit);
+}
+
+static ssize_t is_nak_bit_store(struct device *d,
+				struct device_attribute *attr,
+				const char *buf, size_t count)
+{
+	struct i2c_adapter *adapter = to_i2c_adapter(d);
+	struct cyusbs_i2c *cy_i2c = to_cyusbs_i2c(adapter);
+
+	if ((count != 1) && (count != 2 || buf[1] != '\n'))
+		return -EINVAL;
+
+	if (buf[0] == '0')
+		cy_i2c->is_nak_bit = 0;
+	else if (buf[0] == '1')
+		cy_i2c->is_nak_bit = 1;
+	else
+		return -EINVAL;
+
+	dev_dbg(d, "is_nak_bit=%d buf=%s\n", cy_i2c->is_nak_bit, buf);
+
+	return count;
+}
+
+static DEVICE_ATTR_RO(i2c_read_status);
+static DEVICE_ATTR_RO(i2c_write_status);
+static DEVICE_ATTR_WO(i2c_read_reset);
+static DEVICE_ATTR_WO(i2c_write_reset);
+static DEVICE_ATTR_RW(is_stop_bit);
+static DEVICE_ATTR_RW(is_nak_bit);
+
+static struct attribute *cyusbs_i2c_device_attrs[] = {
+	&dev_attr_i2c_read_status.attr,
+	&dev_attr_i2c_write_status.attr,
+	&dev_attr_i2c_read_reset.attr,
+	&dev_attr_i2c_write_reset.attr,
+	&dev_attr_is_stop_bit.attr,
+	&dev_attr_is_nak_bit.attr,
+	NULL
+};
+
+ATTRIBUTE_GROUPS(cyusbs_i2c_device);
+
+static int cy_i2c_get_status(struct device *d, char *buf, u16 mode)
+{
+	int ret;
+	u16 wIndex, wValue, scb_index;
+	struct i2c_adapter *adapter = to_i2c_adapter(d);
+	struct cyusbs23x *cyusbs = (struct cyusbs23x *)adapter->algo_data;
+	char *data;
+
+	scb_index = cyusbs->intf_num & 0x01;
+	wValue = ((scb_index << CY_SCB_INDEX_POS) | mode);
+	wIndex = 0;
+	data = kmalloc(CY_I2C_XFER_STATUS_LEN, GFP_KERNEL);
+
+	mutex_lock(&cyusbs->lock);
+	/* read the i2c transfer status */
+	ret = usb_control_msg(cyusbs->usb_dev,
+			usb_rcvctrlpipe(cyusbs->usb_dev, 0),
+			CY_I2C_GET_STATUS_CMD,
+			USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
+			wValue, wIndex, data, CY_I2C_XFER_STATUS_LEN, 2000);
+	mutex_unlock(&cyusbs->lock);
+
+	memcpy(buf, data, CY_I2C_XFER_STATUS_LEN);
+	kfree(data);
+
+	dev_dbg(&cyusbs->usb_intf->dev, "%s: %02x %02x %02x\n", __func__,
+		buf[0], buf[1], buf[2]);
+	return ret;
+}
+
+static int cy_i2c_reset(struct device *d, u16 mode)
+{
+	int ret;
+	u16 wIndex, wValue, scb_index;
+	struct i2c_adapter *adapter = to_i2c_adapter(d);
+	struct cyusbs23x *cyusbs = (struct cyusbs23x *)adapter->algo_data;
+
+	scb_index = cyusbs->intf_num & 0x01;
+	wValue = ((scb_index << CY_SCB_INDEX_POS) | mode);
+	wIndex = 0;
+
+	mutex_lock(&cyusbs->lock);
+	ret = usb_control_msg(cyusbs->usb_dev,
+			usb_sndctrlpipe(cyusbs->usb_dev, 0),
+			CY_I2C_RESET_CMD,
+			USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
+			wValue, wIndex, NULL, 0, 2000);
+	mutex_unlock(&cyusbs->lock);
+	dev_dbg(d, "%s: %d\n", __func__, ret);
+	return ret;
+}
+
+static int cy_get_i2c_config(struct cyusbs23x *cyusbs,
+				struct cyusbs_i2c *cy_i2c)
+{
+	int ret;
+	u16 scb_index;
+
+	dev_dbg(&cyusbs->usb_intf->dev, "%s\n", __func__);
+
+	scb_index = (cyusbs->intf_num & 0x01) << CY_SCB_INDEX_POS;
+
+	mutex_lock(&cyusbs->lock);
+	ret = usb_control_msg(cyusbs->usb_dev,
+			usb_rcvctrlpipe(cyusbs->usb_dev, 0),
+			CY_I2C_GET_CONFIG_CMD,
+			USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
+			scb_index, 0, cy_i2c->i2c_config,
+			sizeof(*cy_i2c->i2c_config), 2000);
+	mutex_unlock(&cyusbs->lock);
+
+	dev_dbg(&cyusbs->usb_intf->dev, "%s: %d, 0x%02x, %d, %d, %d, %d, %d\n",
+		__func__, cy_i2c->i2c_config->frequency,
+		cy_i2c->i2c_config->slave_addr,
+		cy_i2c->i2c_config->is_msb_first,
+		cy_i2c->i2c_config->is_master,
+		cy_i2c->i2c_config->s_ignore,
+		cy_i2c->i2c_config->clock_stretch,
+		cy_i2c->i2c_config->is_loopback);
+	return ret;
+}
+
+static int cy_i2c_set_data_config(struct cyusbs23x *cyusbs,
+				  struct cyusbs_i2c *cy_i2c, u16 slave_addr,
+				  u16 length, u8 command)
+{
+	int ret;
+	u16 wIndex, wValue;
+	u16 scb_index;
+
+	dev_dbg(&cyusbs->usb_intf->dev, "%s\n", __func__);
+
+	scb_index = (cyusbs->intf_num & 0x01) << 7;
+	slave_addr = (slave_addr & 0x7F) | scb_index;
+	wValue = cy_i2c->is_stop_bit | cy_i2c->is_nak_bit << 1;
+	wValue |= (slave_addr << 8);
+	wIndex = length;
+
+	dev_dbg(&cyusbs->usb_intf->dev,
+		"%s, cmd=0x%x,val=0x%x,idx=0x%x\n",
+		__func__, command, wValue, wIndex);
+
+	ret = usb_control_msg(cyusbs->usb_dev,
+		usb_sndctrlpipe(cyusbs->usb_dev, 0),
+		command, USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
+		wValue, wIndex, NULL, 0, 2000);
+
+	return ret;
+}
+
+static int cy_i2c_read(struct cyusbs23x *cyusbs, struct i2c_msg *msgs)
+{
+	int ret, actual_read_len = 0;
+
+	dev_dbg(&cyusbs->usb_intf->dev, "%s\n", __func__);
+
+	ret = usb_bulk_msg(cyusbs->usb_dev,
+		usb_rcvbulkpipe(cyusbs->usb_dev, cyusbs->bulk_in_ep_num),
+		msgs[0].buf,
+		msgs[0].len,
+		&actual_read_len, 5000);
+
+	if (ret)
+		dev_dbg(&cyusbs->usb_intf->dev,
+			"read %d/%d returned %d\n",
+			actual_read_len, msgs[0].len, ret);
+
+	return ret;
+}
+
+static int cy_i2c_write(struct cyusbs23x *cyusbs, struct i2c_msg *msgs)
+{
+	int ret, actual_write_len = 0;
+
+	dev_dbg(&cyusbs->usb_intf->dev, "%s\n", __func__);
+
+	ret = usb_bulk_msg(cyusbs->usb_dev,
+		usb_sndbulkpipe(cyusbs->usb_dev, cyusbs->bulk_out_ep_num),
+		msgs[0].buf,
+		msgs[0].len,
+		&actual_write_len, 5000);
+
+	if (ret)
+		dev_dbg(&cyusbs->usb_intf->dev,
+			"write %d/%d returned %d\n",
+			actual_write_len, msgs[0].len, ret);
+
+	return ret;
+}
+
+static int cy_i2c_xfer(struct i2c_adapter *adapter,
+		       struct i2c_msg *msgs, int num)
+{
+	int ret = 0;
+	struct cyusbs_i2c *cy_i2c;
+	struct cyusbs23x *cyusbs = (struct cyusbs23x *)adapter->algo_data;
+
+	dev_dbg(&adapter->dev, "%s\n", __func__);
+
+	if (num > 1) {
+		dev_err(&adapter->dev, "i2c_msg number is > 1\n");
+		return -EIO;
+	}
+
+	cy_i2c = to_cyusbs_i2c(adapter);
+
+	mutex_lock(&cyusbs->lock);
+	if (msgs[0].flags & I2C_M_RD) {
+		dev_dbg(&adapter->dev,
+			"I2C read requested for addr 0x%02x, data length %d\n",
+			msgs[0].addr, msgs[0].len);
+
+		ret = cy_i2c_set_data_config(cyusbs, cy_i2c, msgs[0].addr,
+				msgs[0].len, CY_I2C_READ_CMD);
+
+		if (ret < 0) {
+			dev_err(&adapter->dev,
+				"Set Config (read) failed with %d\n", ret);
+			goto io_error;
+		}
+
+		ret = cy_i2c_read(cyusbs, msgs);
+		if (ret) {
+			dev_err(&adapter->dev,
+				"Read failed with error code %d\n", ret);
+			goto io_error;
+		}
+	} else {
+		dev_dbg(&adapter->dev,
+			"I2C write requested for addr 0x%02x, data length %d\n",
+			msgs[0].addr, msgs[0].len);
+
+		ret = cy_i2c_set_data_config(cyusbs, cy_i2c, msgs[0].addr,
+				msgs[0].len, CY_I2C_WRITE_CMD);
+
+		if (ret < 0) {
+			dev_err(&adapter->dev,
+			"Set Config (write) failed with %d\n", ret);
+			goto io_error;
+		}
+
+		ret = cy_i2c_write(cyusbs, msgs);
+		if (ret) {
+			dev_err(&adapter->dev,
+				"Write failed with error code %d\n", ret);
+			goto io_error;
+		}
+	}
+	mutex_unlock(&cyusbs->lock);
+	return ret;
+
+io_error:
+	mutex_unlock(&cyusbs->lock);
+	return ret;
+}
+
+static u32 cy_i2c_func(struct i2c_adapter *adapter)
+{
+	dev_dbg(&adapter->dev, "%s\n", __func__);
+	return I2C_FUNC_I2C;
+}
+
+static const struct i2c_algorithm i2c_cyusbs23x_algorithm = {
+	.master_xfer	= cy_i2c_xfer,
+	.functionality	= cy_i2c_func,
+};
+
+static int cyusbs23x_i2c_probe(struct platform_device *pdev)
+{
+	struct cyusbs23x *cyusbs;
+	struct cyusbs_i2c *cy_i2c;
+	int ret = 0;
+
+	dev_dbg(&pdev->dev, "%s\n", __func__);
+
+	cyusbs = dev_get_drvdata(pdev->dev.parent);
+
+	cy_i2c = devm_kzalloc(&pdev->dev, sizeof(*cy_i2c), GFP_KERNEL);
+	if (cy_i2c == NULL)
+		return -ENOMEM;
+
+	cy_i2c->i2c_config = kmalloc(sizeof(struct cyusbs_i2c_config),
+					GFP_KERNEL);
+	if (cy_i2c->i2c_config == NULL)
+		return -ENOMEM;
+
+	cy_i2c->is_stop_bit = 1;
+	cy_i2c->is_nak_bit = 1;
+
+	cy_i2c->i2c_adapter.owner = THIS_MODULE;
+	cy_i2c->i2c_adapter.class = I2C_CLASS_HWMON;
+	cy_i2c->i2c_adapter.algo = &i2c_cyusbs23x_algorithm;
+	cy_i2c->i2c_adapter.algo_data = cyusbs;
+	snprintf(cy_i2c->i2c_adapter.name, sizeof(cy_i2c->i2c_adapter.name),
+			"cyusbs23x_i2c at bus %03d dev %03d intf %03d",
+			cyusbs->usb_dev->bus->busnum, cyusbs->usb_dev->devnum,
+			cyusbs->intf_num);
+	cy_i2c->i2c_adapter.dev.parent = &pdev->dev;
+	cy_i2c->i2c_adapter.dev.groups = cyusbs_i2c_device_groups;
+
+	ret = cy_get_i2c_config(cyusbs, cy_i2c);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "error to get i2c config\n");
+		goto error;
+	}
+
+	if (!cy_i2c->i2c_config->is_master) {
+		ret = -EIO;
+		dev_err(&pdev->dev, "not an I2C master\n");
+		goto error;
+	}
+
+	ret = i2c_add_adapter(&cy_i2c->i2c_adapter);
+	if (ret != 0) {
+		dev_err(&pdev->dev, "failed to add i2c adapter\n");
+		goto error;
+	}
+
+	platform_set_drvdata(pdev, cy_i2c);
+
+	dev_dbg(&pdev->dev, "added I2C adapter\n");
+	return 0;
+
+error:
+	dev_dbg(&pdev->dev, "error occured %d\n", ret);
+	kfree(cy_i2c->i2c_config);
+	return ret;
+}
+
+static int cyusbs23x_i2c_remove(struct platform_device *pdev)
+{
+	struct cyusbs_i2c *cy_i2c = platform_get_drvdata(pdev);
+
+	dev_dbg(&pdev->dev, "%s\n", __func__);
+	kfree(cy_i2c->i2c_config);
+	i2c_del_adapter(&cy_i2c->i2c_adapter);
+	return 0;
+}
+
+static struct platform_driver cyusbs23x_i2c_driver = {
+	.driver.name	= "cyusbs23x-i2c",
+	.driver.owner	= THIS_MODULE,
+	.probe		= cyusbs23x_i2c_probe,
+	.remove		= cyusbs23x_i2c_remove,
+};
+
+module_platform_driver(cyusbs23x_i2c_driver);
+
+MODULE_AUTHOR("Rajaram Regupathy <rera@xxxxxxxxxxx>");
+MODULE_AUTHOR("Muthu Mani <muth@xxxxxxxxxxx>");
+MODULE_DESCRIPTION("I2C adapter driver for CYUSBS23x");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:cyusbs23x-i2c");
-- 
1.8.3.2

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