1 files changed, 305 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-tiny-usb.c b/drivers/i2c/busses/i2c-tiny-usb.c
new file mode 100644
index 0000000000..1bffe36c40
--- /dev/null
+++ b/drivers/i2c/busses/i2c-tiny-usb.c
@@ -0,0 +1,305 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * driver for the i2c-tiny-usb adapter - 1.0
+ * http://www.harbaum.org/till/i2c_tiny_usb
+ *
+ * Copyright (C) 2006-2007 Till Harbaum (Till@Harbaum.org)
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+/* include interfaces to usb layer */
+#include <linux/usb.h>
+
+/* include interface to i2c layer */
+#include <linux/i2c.h>
+
+/* commands via USB, must match command ids in the firmware */
+#define CMD_ECHO		0
+#define CMD_GET_FUNC		1
+#define CMD_SET_DELAY		2
+#define CMD_GET_STATUS		3
+
+#define CMD_I2C_IO		4
+#define CMD_I2C_IO_BEGIN	(1<<0)
+#define CMD_I2C_IO_END		(1<<1)
+
+/* i2c bit delay, default is 10us -> 100kHz max
+   (in practice, due to additional delays in the i2c bitbanging
+   code this results in a i2c clock of about 50kHz) */
+static unsigned short delay = 10;
+module_param(delay, ushort, 0);
+MODULE_PARM_DESC(delay, "bit delay in microseconds "
+		 "(default is 10us for 100kHz max)");
+
+static int usb_read(struct i2c_adapter *adapter, int cmd,
+		    int value, int index, void *data, int len);
+
+static int usb_write(struct i2c_adapter *adapter, int cmd,
+		     int value, int index, void *data, int len);
+
+/* ----- begin of i2c layer ---------------------------------------------- */
+
+#define STATUS_IDLE		0
+#define STATUS_ADDRESS_ACK	1
+#define STATUS_ADDRESS_NAK	2
+
+static int usb_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
+{
+	unsigned char *pstatus;
+	struct i2c_msg *pmsg;
+	int i, ret;
+
+	dev_dbg(&adapter->dev, "master xfer %d messages:\n", num);
+
+	pstatus = kmalloc(sizeof(*pstatus), GFP_KERNEL);
+	if (!pstatus)
+		return -ENOMEM;
+
+	for (i = 0 ; i < num ; i++) {
+		int cmd = CMD_I2C_IO;
+
+		if (i == 0)
+			cmd |= CMD_I2C_IO_BEGIN;
+
+		if (i == num-1)
+			cmd |= CMD_I2C_IO_END;
+
+		pmsg = &msgs[i];
+
+		dev_dbg(&adapter->dev,
+			"  %d: %s (flags %d) %d bytes to 0x%02x\n",
+			i, pmsg->flags & I2C_M_RD ? "read" : "write",
+			pmsg->flags, pmsg->len, pmsg->addr);
+
+		/* and directly send the message */
+		if (pmsg->flags & I2C_M_RD) {
+			/* read data */
+			if (usb_read(adapter, cmd,
+				     pmsg->flags, pmsg->addr,
+				     pmsg->buf, pmsg->len) != pmsg->len) {
+				dev_err(&adapter->dev,
+					"failure reading data\n");
+				ret = -EIO;
+				goto out;
+			}
+		} else {
+			/* write data */
+			if (usb_write(adapter, cmd,
+				      pmsg->flags, pmsg->addr,
+				      pmsg->buf, pmsg->len) != pmsg->len) {
+				dev_err(&adapter->dev,
+					"failure writing data\n");
+				ret = -EIO;
+				goto out;
+			}
+		}
+
+		/* read status */
+		if (usb_read(adapter, CMD_GET_STATUS, 0, 0, pstatus, 1) != 1) {
+			dev_err(&adapter->dev, "failure reading status\n");
+			ret = -EIO;
+			goto out;
+		}
+
+		dev_dbg(&adapter->dev, "  status = %d\n", *pstatus);
+		if (*pstatus == STATUS_ADDRESS_NAK) {
+			ret = -ENXIO;
+			goto out;
+		}
+	}
+
+	ret = i;
+out:
+	kfree(pstatus);
+	return ret;
+}
+
+static u32 usb_func(struct i2c_adapter *adapter)
+{
+	__le32 *pfunc;
+	u32 ret;
+
+	pfunc = kmalloc(sizeof(*pfunc), GFP_KERNEL);
+
+	/* get functionality from adapter */
+	if (!pfunc || usb_read(adapter, CMD_GET_FUNC, 0, 0, pfunc,
+			       sizeof(*pfunc)) != sizeof(*pfunc)) {
+		dev_err(&adapter->dev, "failure reading functionality\n");
+		ret = 0;
+		goto out;
+	}
+
+	ret = le32_to_cpup(pfunc);
+out:
+	kfree(pfunc);
+	return ret;
+}
+
+/* This is the actual algorithm we define */
+static const struct i2c_algorithm usb_algorithm = {
+	.master_xfer	= usb_xfer,
+	.functionality	= usb_func,
+};
+
+/* ----- end of i2c layer ------------------------------------------------ */
+
+/* ----- begin of usb layer ---------------------------------------------- */
+
+/*
+ * Initially the usb i2c interface uses a vid/pid pair donated by
+ * Future Technology Devices International Ltd., later a pair was
+ * bought from EZPrototypes
+ */
+static const struct usb_device_id i2c_tiny_usb_table[] = {
+	{ USB_DEVICE(0x0403, 0xc631) },   /* FTDI */
+	{ USB_DEVICE(0x1c40, 0x0534) },   /* EZPrototypes */
+	{ }                               /* Terminating entry */
+};
+
+MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table);
+
+/* Structure to hold all of our device specific stuff */
+struct i2c_tiny_usb {
+	struct usb_device *usb_dev; /* the usb device for this device */
+	struct usb_interface *interface; /* the interface for this device */
+	struct i2c_adapter adapter; /* i2c related things */
+};
+
+static int usb_read(struct i2c_adapter *adapter, int cmd,
+		    int value, int index, void *data, int len)
+{
+	struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
+	void *dmadata = kmalloc(len, GFP_KERNEL);
+	int ret;
+
+	if (!dmadata)
+		return -ENOMEM;
+
+	/* do control transfer */
+	ret = usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
+			       cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
+			       USB_DIR_IN, value, index, dmadata, len, 2000);
+
+	memcpy(data, dmadata, len);
+	kfree(dmadata);
+	return ret;
+}
+
+static int usb_write(struct i2c_adapter *adapter, int cmd,
+		     int value, int index, void *data, int len)
+{
+	struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
+	void *dmadata = kmemdup(data, len, GFP_KERNEL);
+	int ret;
+
+	if (!dmadata)
+		return -ENOMEM;
+
+	/* do control transfer */
+	ret = usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
+			       cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
+			       value, index, dmadata, len, 2000);
+
+	kfree(dmadata);
+	return ret;
+}
+
+static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
+{
+	usb_put_dev(dev->usb_dev);
+	kfree(dev);
+}
+
+static int i2c_tiny_usb_probe(struct usb_interface *interface,
+			      const struct usb_device_id *id)
+{
+	struct i2c_tiny_usb *dev;
+	int retval = -ENOMEM;
+	u16 version;
+
+	if (interface->intf_assoc &&
+	    interface->intf_assoc->bFunctionClass != USB_CLASS_VENDOR_SPEC)
+		return -ENODEV;
+
+	dev_dbg(&interface->dev, "probing usb device\n");
+
+	/* allocate memory for our device state and initialize it */
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		goto error;
+
+	dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));
+	dev->interface = interface;
+
+	/* save our data pointer in this interface device */
+	usb_set_intfdata(interface, dev);
+
+	version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice);
+	dev_info(&interface->dev,
+		 "version %x.%02x found at bus %03d address %03d\n",
+		 version >> 8, version & 0xff,
+		 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
+
+	/* setup i2c adapter description */
+	dev->adapter.owner = THIS_MODULE;
+	dev->adapter.class = I2C_CLASS_HWMON;
+	dev->adapter.algo = &usb_algorithm;
+	dev->adapter.algo_data = dev;
+	snprintf(dev->adapter.name, sizeof(dev->adapter.name),
+		 "i2c-tiny-usb at bus %03d device %03d",
+		 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
+
+	if (usb_write(&dev->adapter, CMD_SET_DELAY, delay, 0, NULL, 0) != 0) {
+		dev_err(&dev->adapter.dev,
+			"failure setting delay to %dus\n", delay);
+		retval = -EIO;
+		goto error;
+	}
+
+	dev->adapter.dev.parent = &dev->interface->dev;
+
+	/* and finally attach to i2c layer */
+	i2c_add_adapter(&dev->adapter);
+
+	/* inform user about successful attachment to i2c layer */
+	dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n");
+
+	return 0;
+
+ error:
+	if (dev)
+		i2c_tiny_usb_free(dev);
+
+	return retval;
+}
+
+static void i2c_tiny_usb_disconnect(struct usb_interface *interface)
+{
+	struct i2c_tiny_usb *dev = usb_get_intfdata(interface);
+
+	i2c_del_adapter(&dev->adapter);
+	usb_set_intfdata(interface, NULL);
+	i2c_tiny_usb_free(dev);
+
+	dev_dbg(&interface->dev, "disconnected\n");
+}
+
+static struct usb_driver i2c_tiny_usb_driver = {
+	.name		= "i2c-tiny-usb",
+	.probe		= i2c_tiny_usb_probe,
+	.disconnect	= i2c_tiny_usb_disconnect,
+	.id_table	= i2c_tiny_usb_table,
+};
+
+module_usb_driver(i2c_tiny_usb_driver);
+
+/* ----- end of usb layer ------------------------------------------------ */
+
+MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");
+MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");
+MODULE_LICENSE("GPL");