[PATCH v1 0/1] HID: mcp2221: add usb to i2c-smbus host bridge driver

[PATCH v1 0/1] HID: mcp2221: add usb to i2c-smbus host bridge driver

[Rishi Gupta]

MCP2221 is a USB HID to I2C/SMbus host bridge device. This
commit implements i2c and smbus host adapter support. 7-bit
address and i2c multi-message transaction is also supported.

Different transactions have been tested with various common
hardwares, linux driver and user space tools.

Host PC communicates with mcp2221a over usb using raw hid protocol.
Reports are exchanged using interrupt end points. Command and responses
are mcp2221a specific and documented in datasheet:
http://ww1.microchip.com/downloads/en/DeviceDoc/20005565B.pdf

There is only 1 patch in this driver submission.

Rishi Gupta (1):
  HID: mcp2221: add usb to i2c-smbus host bridge driver

 drivers/hid/Kconfig       |  10 +
 drivers/hid/Makefile      |   1 +
 drivers/hid/hid-ids.h     |   1 +
 drivers/hid/hid-mcp2221.c | 773 ++++++++++++++++++++++++++++++++++++++++++++++
 drivers/hid/hid-quirks.c  |   3 +
 5 files changed, 788 insertions(+)
 create mode 100644 drivers/hid/hid-mcp2221.c

-- 
2.7.4

[PATCH v1 1/1] HID: mcp2221: add usb to i2c-smbus host bridge driver

[Rishi Gupta]

MCP2221 is a USB HID to I2C/SMbus host bridge device. This
commit implements i2c and smbus host adapter support. 7-bit
address and i2c multi-message transaction is also supported.

Signed-off-by: Rishi Gupta <gupt21@gmail.com>
---
 drivers/hid/Kconfig       |  10 +
 drivers/hid/Makefile      |   1 +
 drivers/hid/hid-ids.h     |   1 +
 drivers/hid/hid-mcp2221.c | 773 ++++++++++++++++++++++++++++++++++++++++++++++
 drivers/hid/hid-quirks.c  |   3 +
 5 files changed, 788 insertions(+)
 create mode 100644 drivers/hid/hid-mcp2221.c

diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index 494a39e..3f0edca 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -1145,6 +1145,16 @@ config HID_ALPS
 	Say Y here if you have a Alps touchpads over i2c-hid or usbhid
 	and want support for its special functionalities.
 
+config HID_MCP2221
+	tristate "Silicon Labs MCP2221 HID USB-to-I2C/SMbus host support"
+	depends on USB_HID && HIDRAW && I2C
+	---help---
+	Provides I2C host adapter functionality over USB through MCP2221
+	from Silicon Labs. I2C bus speed can be set during driver loading.
+
+	To compile this driver as a module, choose M here: the module
+	will be called hid-mcp2221.ko.
+
 endmenu
 
 endif # HID
diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
index bfefa36..567a241 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -71,6 +71,7 @@ obj-$(CONFIG_HID_MACALLY)	+= hid-macally.o
 obj-$(CONFIG_HID_MAGICMOUSE)	+= hid-magicmouse.o
 obj-$(CONFIG_HID_MALTRON)	+= hid-maltron.o
 obj-$(CONFIG_HID_MAYFLASH)	+= hid-mf.o
+obj-$(CONFIG_HID_MCP2221)	+= hid-mcp2221.o
 obj-$(CONFIG_HID_MICROSOFT)	+= hid-microsoft.o
 obj-$(CONFIG_HID_MONTEREY)	+= hid-monterey.o
 obj-$(CONFIG_HID_MULTITOUCH)	+= hid-multitouch.o
diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
index 3a400ce..53236ac 100644
--- a/drivers/hid/hid-ids.h
+++ b/drivers/hid/hid-ids.h
@@ -819,6 +819,7 @@
 #define USB_DEVICE_ID_PICK16F1454	0x0042
 #define USB_DEVICE_ID_PICK16F1454_V2	0xf2f7
 #define USB_DEVICE_ID_LUXAFOR		0xf372
+#define USB_DEVICE_ID_MCP2221		0x00dd
 
 #define USB_VENDOR_ID_MICROSOFT		0x045e
 #define USB_DEVICE_ID_SIDEWINDER_GV	0x003b
diff --git a/drivers/hid/hid-mcp2221.c b/drivers/hid/hid-mcp2221.c
new file mode 100644
index 0000000..9897599
--- /dev/null
+++ b/drivers/hid/hid-mcp2221.c
@@ -0,0 +1,773 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MCP2221A - Silicon Labs USB to I2C Protocol Bridge
+ *
+ * Copyright (c) 2019, Rishi Gupta <gupt21@gmail.com>
+ *
+ * Datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/20005565B.pdf
+ */
+
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/mutex.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/hid.h>
+#include <linux/usb.h>
+#include <linux/i2c.h>
+#include "hid-ids.h"
+
+/* Commands codes in a raw output report */
+#define MCP2221_I2C_WR_DATA			0x90
+#define MCP2221_I2C_WR_NO_STOP		0x94
+#define MCP2221_I2C_RD_DATA			0x91
+#define MCP2221_I2C_RD_RPT_START	0x93
+#define MCP2221_I2C_GET_DATA		0x40
+#define MCP2221_I2C_PARAM_OR_STATUS	0x10
+#define MCP2221_I2C_SET_SPEED		0x20
+#define MCP2221_I2C_CANCEL			0x10
+
+/* Response codes in a raw input report */
+#define MCP2221_SUCCESS				0x00
+#define MCP2221_I2C_ENG_BUSY		0x01
+#define MCP2221_I2C_START_TOUT		0x12
+#define MCP2221_I2C_STOP_TOUT		0x62
+#define MCP2221_I2C_WRADDRL_TOUT	0x23
+#define MCP2221_I2C_WRDATA_TOUT		0x44
+#define MCP2221_I2C_WRADDRL_NACK	0x25
+#define MCP2221_I2C_MASK_ADDR_NACK	0x40
+#define MCP2221_I2C_WRADDRL_SEND	0x21
+#define MCP2221_I2C_ADDR_NACK		0x25
+#define MCP2221_I2C_READ_COMPL		0x55
+
+/*
+ * There is no way to distinguish responses. Therefore next command
+ * is sent only after response to previous has been received. Mutex
+ * lock is used for this purpose mainly.
+ */
+struct mcp2221 {
+	struct hid_device *hdev;
+	struct i2c_adapter adapter;
+	struct mutex lock;
+	struct completion wait_in_report;
+	u8 *rxbuf;
+	u8 txbuf[64];
+	int rxbuf_idx;
+	int status;
+	u8 cur_i2c_clk_div;
+};
+
+/*
+ * Default i2c bus clock frequency in kHz. Override through
+ * module param if required.
+ */
+static uint i2c_clk_freq = 400;
+
+/* Synchronously send output report to the device */
+static int mcp_send_report(struct mcp2221 *mcp,
+					u8 *out_report, size_t len)
+{
+	u8 *buf;
+	int ret;
+
+	buf = kmemdup(out_report, len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	/* mcp2221 uses interrupt endpoint for out reports */
+	ret = hid_hw_output_report(mcp->hdev, buf, len);
+	kfree(buf);
+
+	if (ret < 0)
+		return ret;
+	return 0;
+}
+
+/*
+ * Send o/p report to the device and wait for i/p report to be
+ * received from the device. If the device does not respond,
+ * we timeout.
+ */
+static int mcp_send_data_req_status(struct mcp2221 *mcp,
+			u8 *out_report, int len)
+{
+	int ret;
+	unsigned long t;
+
+	reinit_completion(&mcp->wait_in_report);
+
+	ret = mcp_send_report(mcp, out_report, len);
+	if (ret)
+		return ret;
+
+	t = wait_for_completion_timeout(&mcp->wait_in_report,
+							msecs_to_jiffies(4000));
+	if (!t)
+		return -ETIMEDOUT;
+
+	return mcp->status;
+}
+
+/* Check pass/fail for actual communication with i2c slave */
+static int mcp_chk_last_cmd_status(struct mcp2221 *mcp)
+{
+	int x;
+
+	mcp->txbuf[0] = MCP2221_I2C_PARAM_OR_STATUS;
+
+	for (x = 1; x < 8; x++)
+		mcp->txbuf[x] = 0;
+
+	return mcp_send_data_req_status(mcp, mcp->txbuf, 8);
+}
+
+/* Cancels last command releasing i2c bus just in case occupied */
+static int mcp_cancel_last_cmd(struct mcp2221 *mcp)
+{
+	int x;
+
+	mcp->txbuf[0] = MCP2221_I2C_PARAM_OR_STATUS;
+	mcp->txbuf[1] = 0;
+	mcp->txbuf[2] = MCP2221_I2C_CANCEL;
+
+	for (x = 3; x < 8; x++)
+		mcp->txbuf[x] = 0;
+
+	return mcp_send_data_req_status(mcp, mcp->txbuf, 8);
+}
+
+static int mcp_set_i2c_speed(struct mcp2221 *mcp)
+{
+	int ret;
+
+	mcp->txbuf[0] = MCP2221_I2C_PARAM_OR_STATUS;
+	mcp->txbuf[1] = 0;
+	mcp->txbuf[2] = 0;
+	mcp->txbuf[3] = MCP2221_I2C_SET_SPEED;
+	mcp->txbuf[4] = mcp->cur_i2c_clk_div;
+	mcp->txbuf[5] = 0;
+	mcp->txbuf[6] = 0;
+	mcp->txbuf[7] = 0;
+
+	ret = mcp_send_data_req_status(mcp, mcp->txbuf, 8);
+	if (ret) {
+		/* Small delay is needed here */
+		usleep_range(980, 1000);
+		mcp_cancel_last_cmd(mcp);
+	}
+
+	return 0;
+}
+
+/*
+ * An output report can contain minimum 1 and maximum 60 user data
+ * bytes. If the number of data bytes is more then 60, we send it
+ * in chunks of 60 bytes. Last chunk may contain exactly 60 or less
+ * bytes. Total number of bytes is informed in very first report to
+ * mcp2221, from that point onwards it first collect all the data
+ * from host and then send to i2c slave device.
+ */
+static int mcp_i2c_write(struct mcp2221 *mcp,
+				struct i2c_msg *msg, int type, u8 last_status)
+{
+	int ret, len, idx, loop_count, remainder;
+
+	mcp->txbuf[0] = type;
+	mcp->txbuf[1] = msg->len & 0xff;
+	mcp->txbuf[2] = msg->len >> 8;
+	mcp->txbuf[3] = (u8)(msg->addr << 1);
+
+	if (msg->len < 60)
+		len = msg->len;
+	else
+		len = 60;
+	memcpy(&mcp->txbuf[4], msg->buf, len);
+
+	ret = mcp_send_data_req_status(mcp, mcp->txbuf, len + 4);
+	if (ret)
+		return ret;
+
+	if (last_status) {
+		usleep_range(980, 1000);
+
+		ret = mcp_chk_last_cmd_status(mcp);
+		if (ret)
+			return ret;
+	}
+
+	if (msg->len <= 60)
+		return ret;
+
+	loop_count = (msg->len - 60) / 60;
+	remainder = (msg->len - 60) % 60;
+
+	if (loop_count == 0)
+		len = remainder;
+	else
+		len = 60;
+
+	idx = 60;
+	do {
+		/*
+		 * Testing shows delay is needed between successive writes
+		 * otherwise next write fails on first-try from i2c core.
+		 * This value is obtained through automated stress testing.
+		 */
+		usleep_range(980, 1000);
+
+		memcpy(&mcp->txbuf[4], &msg->buf[idx], len);
+
+		ret = mcp_send_data_req_status(mcp, mcp->txbuf, len + 4);
+		if (ret)
+			return ret;
+
+		usleep_range(980, 1000);
+
+		ret = mcp_chk_last_cmd_status(mcp);
+		if (ret)
+			return ret;
+
+		loop_count--;
+		idx = idx + len;
+		if (loop_count <= 0)
+			len = remainder;
+		else
+			len = 60;
+	} while (len > 0 && idx < msg->len);
+
+	return ret;
+}
+
+/*
+ * Device reads all data (0 - 65535 bytes) from i2c slave device and
+ * stores it in device itself. This data is read back from device to
+ * host in multiples of 60 bytes using input reports.
+ */
+static int mcp_i2c_smbus_read(struct mcp2221 *mcp,
+				struct i2c_msg *msg, int type, u16 smbus_addr,
+				u8 smbus_len, u8 *smbus_buf)
+{
+	int ret;
+	u16 total_len;
+
+	mcp->txbuf[0] = type;
+	if (msg) {
+		mcp->txbuf[1] = msg->len & 0xff;
+		mcp->txbuf[2] = msg->len >> 8;
+		mcp->txbuf[3] = (u8)(msg->addr << 1);
+		total_len = msg->len;
+		mcp->rxbuf = msg->buf;
+	} else {
+		mcp->txbuf[1] = smbus_len;
+		mcp->txbuf[2] = 0;
+		mcp->txbuf[3] = (u8)(smbus_addr << 1);
+		total_len = smbus_len;
+		mcp->rxbuf = smbus_buf;
+	}
+
+	ret = mcp_send_data_req_status(mcp, mcp->txbuf, 4);
+	if (ret)
+		return ret;
+
+	mcp->rxbuf_idx = 0;
+
+	do {
+		mcp->txbuf[0] = MCP2221_I2C_GET_DATA;
+		mcp->txbuf[1] = 0;
+		mcp->txbuf[2] = 0;
+		mcp->txbuf[3] = 0;
+
+		ret = mcp_send_data_req_status(mcp, mcp->txbuf, 1);
+		if (ret)
+			return ret;
+
+		ret = mcp_chk_last_cmd_status(mcp);
+		if (ret)
+			return ret;
+	} while (mcp->rxbuf_idx < total_len);
+
+	return ret;
+}
+
+static int mcp_i2c_xfer(struct i2c_adapter *adapter,
+				struct i2c_msg msgs[], int num)
+{
+	int ret;
+	struct mcp2221 *mcp = i2c_get_adapdata(adapter);
+
+	hid_hw_power(mcp->hdev, PM_HINT_FULLON);
+
+	mutex_lock(&mcp->lock);
+
+	/* Setting speed before every transaction is required for mcp2221 */
+	ret = mcp_set_i2c_speed(mcp);
+	if (ret)
+		goto exit;
+
+	if (num == 1) {
+		if (msgs->flags & I2C_M_RD) {
+			ret = mcp_i2c_smbus_read(mcp, msgs, MCP2221_I2C_RD_DATA,
+							0, 0, NULL);
+		} else {
+			ret = mcp_i2c_write(mcp, msgs, MCP2221_I2C_WR_DATA, 1);
+		}
+		if (ret)
+			goto exit;
+		ret = num;
+	} else if (num == 2) {
+		/* Ex transaction; send reg address and read its contents */
+		if (msgs[0].addr == msgs[1].addr &&
+			!(msgs[0].flags & I2C_M_RD) &&
+			 (msgs[1].flags & I2C_M_RD)) {
+
+			ret = mcp_i2c_write(mcp, &msgs[0],
+						MCP2221_I2C_WR_NO_STOP, 0);
+			if (ret)
+				goto exit;
+
+			ret = mcp_i2c_smbus_read(mcp, &msgs[1],
+						MCP2221_I2C_RD_RPT_START,
+						0, 0, NULL);
+			if (ret)
+				goto exit;
+			ret = num;
+		} else {
+			dev_err(&adapter->dev,
+				"unsupported i2c transaction size: %d\n", num);
+			ret = -EOPNOTSUPP;
+		}
+	} else {
+		dev_err(&adapter->dev,
+			"unsupported i2c transaction size: %d\n", num);
+		ret = -EOPNOTSUPP;
+	}
+
+exit:
+	hid_hw_power(mcp->hdev, PM_HINT_NORMAL);
+	mutex_unlock(&mcp->lock);
+	return ret;
+}
+
+static int mcp_smbus_write(struct mcp2221 *mcp, u16 addr,
+				u8 command, u8 *buf, u8 len, int type,
+				u8 last_status)
+{
+	int data_len, ret;
+
+	mcp->txbuf[0] = type;
+	mcp->txbuf[1] = len;
+	mcp->txbuf[2] = 0;
+	mcp->txbuf[3] = (u8)(addr << 1);
+	mcp->txbuf[4] = command;
+
+	switch (len) {
+	case 0:
+		mcp->txbuf[1] = 1;
+		data_len = 5;
+		break;
+	case 1:
+		mcp->txbuf[5] = buf[0];
+		data_len = 6;
+		break;
+	case 2:
+		mcp->txbuf[5] = buf[0];
+		mcp->txbuf[6] = buf[1];
+		data_len = 7;
+		break;
+	default:
+		memcpy(&mcp->txbuf[5], buf, len);
+		data_len = len + 5;
+	}
+
+	ret = mcp_send_data_req_status(mcp, mcp->txbuf, data_len);
+	if (ret)
+		return ret;
+
+	if (last_status) {
+		usleep_range(980, 1000);
+
+		ret = mcp_chk_last_cmd_status(mcp);
+		if (ret)
+			return ret;
+	}
+
+	return ret;
+}
+
+int mcp_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
+				unsigned short flags, char read_write,
+				u8 command, int size,
+				union i2c_smbus_data *data)
+{
+	int ret;
+	struct mcp2221 *mcp = i2c_get_adapdata(adapter);
+
+	hid_hw_power(mcp->hdev, PM_HINT_FULLON);
+
+	mutex_lock(&mcp->lock);
+
+	ret = mcp_set_i2c_speed(mcp);
+	if (ret)
+		goto exit;
+
+	switch (size) {
+
+	case I2C_SMBUS_QUICK:
+		if (read_write == I2C_SMBUS_READ)
+			ret = mcp_i2c_smbus_read(mcp, NULL, MCP2221_I2C_RD_DATA,
+						addr, 0, &data->byte);
+		else
+			ret = mcp_smbus_write(mcp, addr, command, NULL,
+						0, MCP2221_I2C_WR_DATA, 1);
+		break;
+	case I2C_SMBUS_BYTE:
+		if (read_write == I2C_SMBUS_READ)
+			ret = mcp_i2c_smbus_read(mcp, NULL, MCP2221_I2C_RD_DATA,
+						addr, 1, &data->byte);
+		else
+			ret = mcp_smbus_write(mcp, addr, command, NULL,
+						0, MCP2221_I2C_WR_DATA, 1);
+		break;
+	case I2C_SMBUS_BYTE_DATA:
+		if (read_write == I2C_SMBUS_READ) {
+			ret = mcp_smbus_write(mcp, addr, command, NULL,
+						0, MCP2221_I2C_WR_NO_STOP, 0);
+			if (ret)
+				goto exit;
+
+			ret = mcp_i2c_smbus_read(mcp, NULL,
+						MCP2221_I2C_RD_RPT_START,
+						addr, 1, &data->byte);
+		} else {
+			ret = mcp_smbus_write(mcp, addr, command, &data->byte,
+						1, MCP2221_I2C_WR_DATA, 1);
+		}
+		break;
+	case I2C_SMBUS_WORD_DATA:
+		if (read_write == I2C_SMBUS_READ) {
+			ret = mcp_smbus_write(mcp, addr, command, NULL,
+						0, MCP2221_I2C_WR_NO_STOP, 0);
+			if (ret)
+				goto exit;
+
+			ret = mcp_i2c_smbus_read(mcp, NULL,
+						MCP2221_I2C_RD_RPT_START,
+						addr, 2, (u8 *)&data->word);
+		} else {
+			ret = mcp_smbus_write(mcp, addr, command,
+						(u8 *)&data->word, 2,
+						MCP2221_I2C_WR_DATA, 1);
+		}
+		break;
+	case I2C_SMBUS_BLOCK_DATA:
+		if (read_write == I2C_SMBUS_READ) {
+			ret = mcp_smbus_write(mcp, addr, command, NULL,
+						0, MCP2221_I2C_WR_NO_STOP, 0);
+			if (ret)
+				goto exit;
+
+			mcp->rxbuf = data->block;
+			mcp->txbuf[0] = MCP2221_I2C_GET_DATA;
+			ret = mcp_send_data_req_status(mcp, mcp->txbuf, 1);
+			if (ret)
+				goto exit;
+		} else {
+			if (!data->block[0]) {
+				ret = -EINVAL;
+				goto exit;
+			}
+			ret = mcp_smbus_write(mcp, addr, command, data->block,
+						data->block[0] + 1,
+						MCP2221_I2C_WR_DATA, 1);
+		}
+		break;
+	case I2C_SMBUS_I2C_BLOCK_DATA:
+		if (read_write == I2C_SMBUS_READ) {
+			ret = mcp_smbus_write(mcp, addr, command, NULL,
+						0, MCP2221_I2C_WR_NO_STOP, 1);
+			if (ret)
+				goto exit;
+
+			mcp->rxbuf = data->block;
+			mcp->txbuf[0] = MCP2221_I2C_GET_DATA;
+			ret = mcp_send_data_req_status(mcp, mcp->txbuf, 1);
+			if (ret)
+				goto exit;
+		} else {
+			if (!data->block[0]) {
+				ret = -EINVAL;
+				goto exit;
+			}
+			ret = mcp_smbus_write(mcp, addr, command,
+						&data->block[1], data->block[0],
+						MCP2221_I2C_WR_DATA, 1);
+		}
+		break;
+	case I2C_SMBUS_PROC_CALL:
+		ret = mcp_smbus_write(mcp, addr, command,
+						(u8 *)&data->word,
+						2, MCP2221_I2C_WR_NO_STOP, 0);
+		if (ret)
+			goto exit;
+
+		ret = mcp_i2c_smbus_read(mcp, NULL,
+						MCP2221_I2C_RD_RPT_START,
+						addr, 2, (u8 *)&data->word);
+		break;
+	case I2C_SMBUS_BLOCK_PROC_CALL:
+		ret = mcp_smbus_write(mcp, addr, command, data->block,
+						data->block[0] + 1,
+						MCP2221_I2C_WR_NO_STOP, 0);
+		if (ret)
+			goto exit;
+
+		ret = mcp_i2c_smbus_read(mcp, NULL,
+						MCP2221_I2C_RD_RPT_START,
+						addr, I2C_SMBUS_BLOCK_MAX,
+						data->block);
+		break;
+
+	default:
+		dev_err(&mcp->adapter.dev,
+			"unsupported smbus transaction size:%d\n", size);
+		ret = -EOPNOTSUPP;
+	}
+
+exit:
+	hid_hw_power(mcp->hdev, PM_HINT_NORMAL);
+	mutex_unlock(&mcp->lock);
+	return ret;
+}
+
+static u32 mcp_i2c_func(struct i2c_adapter *adapter)
+{
+	return I2C_FUNC_I2C |
+			I2C_FUNC_SMBUS_READ_BLOCK_DATA |
+			I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
+			(I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_PEC);
+}
+
+static const struct i2c_algorithm mcp_i2c_algo = {
+	.master_xfer = mcp_i2c_xfer,
+	.smbus_xfer = mcp_smbus_xfer,
+	.functionality = mcp_i2c_func,
+};
+
+static int mcp_get_i2c_eng_state(struct mcp2221 *mcp,
+				u8 *data, u8 idx)
+{
+	int ret;
+
+	switch (data[idx]) {
+	case MCP2221_I2C_WRADDRL_NACK:
+	case MCP2221_I2C_WRADDRL_SEND:
+		ret = -ENXIO;
+		break;
+	case MCP2221_I2C_START_TOUT:
+	case MCP2221_I2C_STOP_TOUT:
+	case MCP2221_I2C_WRADDRL_TOUT:
+	case MCP2221_I2C_WRDATA_TOUT:
+		ret = -ETIMEDOUT;
+		break;
+	case MCP2221_I2C_ENG_BUSY:
+		ret = -EAGAIN;
+		break;
+	case MCP2221_SUCCESS:
+		ret = 0x00;
+		break;
+	default:
+		ret = -EIO;
+	}
+
+	return ret;
+}
+
+/*
+ * MCP2221 uses interrupt endpoint for input reports. This function
+ * is called by HID layer when it receives i/p report from mcp2221,
+ * which is actually a response to the previously sent command.
+ *
+ * MCP2221A firmware specific return codes are parsed and 0 or
+ * appropriate negative error code is returned. Delayed response
+ * results in timeout error and stray reponses results in -EIO.
+ */
+static int mcp2221_raw_event(struct hid_device *hdev,
+				struct hid_report *report, u8 *data, int size)
+{
+	u8 *buf;
+	struct mcp2221 *mcp = hid_get_drvdata(hdev);
+
+	switch (data[0]) {
+
+	case MCP2221_I2C_WR_DATA:
+	case MCP2221_I2C_WR_NO_STOP:
+	case MCP2221_I2C_RD_DATA:
+	case MCP2221_I2C_RD_RPT_START:
+		switch (data[1]) {
+		case MCP2221_SUCCESS:
+			mcp->status = 0;
+			break;
+		default:
+			mcp->status = mcp_get_i2c_eng_state(mcp, data, 2);
+		}
+		complete(&mcp->wait_in_report);
+		break;
+
+	case MCP2221_I2C_PARAM_OR_STATUS:
+		switch (data[1]) {
+		case MCP2221_SUCCESS:
+			if ((mcp->txbuf[3] == MCP2221_I2C_SET_SPEED) &&
+				(data[3] != MCP2221_I2C_SET_SPEED)) {
+				mcp->status = -EAGAIN;
+				break;
+			}
+			if (data[20] & MCP2221_I2C_MASK_ADDR_NACK) {
+				mcp->status = -ENXIO;
+				break;
+			}
+			mcp->status = mcp_get_i2c_eng_state(mcp, data, 8);
+			break;
+		default:
+			mcp->status = -EIO;
+		}
+		complete(&mcp->wait_in_report);
+		break;
+
+	case MCP2221_I2C_GET_DATA:
+		switch (data[1]) {
+		case MCP2221_SUCCESS:
+			if (data[2] == MCP2221_I2C_ADDR_NACK) {
+				mcp->status = -ENXIO;
+				break;
+			}
+			if (!mcp_get_i2c_eng_state(mcp, data, 2)
+				&& (data[3] == 0)) {
+				mcp->status = 0;
+				break;
+			}
+			if (data[3] == 127) {
+				mcp->status = -EIO;
+				break;
+			}
+			if (data[2] == MCP2221_I2C_READ_COMPL) {
+				buf = mcp->rxbuf;
+				memcpy(&buf[mcp->rxbuf_idx], &data[4], data[3]);
+				mcp->rxbuf_idx = mcp->rxbuf_idx + data[3];
+				mcp->status = 0;
+				break;
+			}
+			mcp->status = -EIO;
+			break;
+		default:
+			mcp->status = -EIO;
+		}
+		complete(&mcp->wait_in_report);
+		break;
+
+	default:
+		mcp->status = -EIO;
+		complete(&mcp->wait_in_report);
+	}
+
+	return 1;
+}
+
+static int mcp2221_probe(struct hid_device *hdev,
+					const struct hid_device_id *id)
+{
+	int ret;
+	struct mcp2221 *mcp;
+	struct usb_device *usd = to_usb_device(hdev->dev.parent->parent);
+
+	mcp = devm_kzalloc(&hdev->dev, sizeof(*mcp), GFP_KERNEL);
+	if (!mcp)
+		return -ENOMEM;
+
+	ret = hid_parse(hdev);
+	if (ret) {
+		hid_err(hdev, "can't parse reports\n");
+		return ret;
+	}
+
+	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+	if (ret) {
+		hid_err(hdev, "can't start hardware\n");
+		return ret;
+	}
+
+	ret = hid_hw_open(hdev);
+	if (ret) {
+		hid_err(hdev, "can't open device\n");
+		goto err_hstop;
+	}
+
+	mutex_init(&mcp->lock);
+	init_completion(&mcp->wait_in_report);
+	hid_set_drvdata(hdev, mcp);
+	mcp->hdev = hdev;
+
+	/* Set I2C bus clock diviser */
+	if (i2c_clk_freq > 400)
+		i2c_clk_freq = 400;
+	if (i2c_clk_freq < 50)
+		i2c_clk_freq = 50;
+	mcp->cur_i2c_clk_div = (12000000 / (i2c_clk_freq * 1000)) - 3;
+
+	mcp->adapter.owner = THIS_MODULE;
+	mcp->adapter.class = I2C_CLASS_HWMON;
+	mcp->adapter.algo = &mcp_i2c_algo;
+	mcp->adapter.retries = 1;
+	mcp->adapter.dev.parent = &hdev->dev;
+	snprintf(mcp->adapter.name, sizeof(mcp->adapter.name),
+		"mcp2221 at usb bus %03d dev %03d", usd->bus->busnum,
+		usd->devnum);
+
+	ret = i2c_add_adapter(&mcp->adapter);
+	if (ret) {
+		hid_err(hdev, "can't add usb-i2c adapter: %d\n", ret);
+		goto err_i2c;
+	}
+	i2c_set_adapdata(&mcp->adapter, mcp);
+
+	return 0;
+
+err_i2c:
+	hid_hw_close(mcp->hdev);
+err_hstop:
+	hid_hw_stop(mcp->hdev);
+	return ret;
+}
+
+static void mcp2221_remove(struct hid_device *hdev)
+{
+	struct mcp2221 *mcp = hid_get_drvdata(hdev);
+
+	i2c_del_adapter(&mcp->adapter);
+	hid_hw_close(mcp->hdev);
+	hid_hw_stop(mcp->hdev);
+}
+
+static const struct hid_device_id mcp2221_devices[] = {
+	{ HID_USB_DEVICE(0x04d8, 0x00dd) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, mcp2221_devices);
+
+static struct hid_driver mcp2221_driver = {
+	.name		= "mcp2221",
+	.id_table	= mcp2221_devices,
+	.probe		= mcp2221_probe,
+	.remove		= mcp2221_remove,
+	.raw_event	= mcp2221_raw_event,
+};
+
+/* Register with HID core */
+module_hid_driver(mcp2221_driver);
+
+/* I2C bus clock frequency can be set only during driver loading */
+module_param(i2c_clk_freq, uint, 0444);
+MODULE_PARM_DESC(i2c_clk_freq, "I2C bus clock frequency 50-400 kHz");
+
+MODULE_AUTHOR("Rishi Gupta <gupt21@gmail.com>");
+MODULE_DESCRIPTION("MCP2221 Silicon Labs HID USB to I2C master bridge");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/hid/hid-quirks.c b/drivers/hid/hid-quirks.c
index 0e7b2d9..ee815eb 100644
--- a/drivers/hid/hid-quirks.c
+++ b/drivers/hid/hid-quirks.c
@@ -473,6 +473,9 @@ static const struct hid_device_id hid_have_special_driver[] = {
 	{ HID_USB_DEVICE(USB_VENDOR_ID_DRAGONRISE, USB_DEVICE_ID_DRAGONRISE_GAMECUBE1) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_DRAGONRISE, USB_DEVICE_ID_DRAGONRISE_GAMECUBE2) },
 #endif
+#if IS_ENABLED(CONFIG_HID_MCP2221)
+	{ HID_USB_DEVICE(USB_VENDOR_ID_MICROCHIP, USB_DEVICE_ID_MCP2221) },
+#endif
 #if IS_ENABLED(CONFIG_HID_MICROSOFT)
 	{ HID_USB_DEVICE(USB_VENDOR_ID_MICROSOFT, USB_DEVICE_ID_MS_COMFORT_MOUSE_4500) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_MICROSOFT, USB_DEVICE_ID_MS_COMFORT_KEYBOARD) },
-- 
2.7.4

Re: [PATCH v1 1/1] HID: mcp2221: add usb to i2c-smbus host bridge driver

[kbuild test robot]

Hi Rishi,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[also build test WARNING on v5.5-rc7 next-20200117]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Rishi-Gupta/HID-mcp2221-add-usb-to-i2c-smbus-host-bridge-driver/20200120-133043
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git def9d2780727cec3313ed3522d0123158d87224d
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.1-131-g22978b6b-dirty
        make ARCH=x86_64 allmodconfig
        make C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>


sparse warnings: (new ones prefixed by >>)

>> drivers/hid/hid-mcp2221.c:397:5: sparse: sparse: symbol 'mcp_smbus_xfer' was not declared. Should it be static?

Please review and possibly fold the followup patch.

---
0-DAY kernel test infrastructure                 Open Source Technology Center
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org Intel Corporation

[RFC PATCH] HID: mcp2221: mcp_smbus_xfer() can be static

[kbuild test robot]

Fixes: 38f8a303aca6 ("HID: mcp2221: add usb to i2c-smbus host bridge driver")
Signed-off-by: kbuild test robot <lkp@intel.com>
---
 hid-mcp2221.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hid/hid-mcp2221.c b/drivers/hid/hid-mcp2221.c
index 9897599a868bf..b0e7ea0d267d0 100644
--- a/drivers/hid/hid-mcp2221.c
+++ b/drivers/hid/hid-mcp2221.c
@@ -394,7 +394,7 @@ static int mcp_smbus_write(struct mcp2221 *mcp, u16 addr,
 	return ret;
 }
 
-int mcp_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
+static int mcp_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
 				unsigned short flags, char read_write,
 				u8 command, int size,
 				union i2c_smbus_data *data)