Re: [PATCH v3] HID: mcp2221: add usb to i2c-smbus host bridge

From: rishi gupta
Date: Mon Feb 10 2020 - 08:50:38 EST

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Humble request for review (all suggestions addressed & tested).
GPIO support is also ready, once this patch is Acknowledged I will
submit that also.

Regards,
Rishi

On Tue, Jan 28, 2020 at 9:49 AM Rishi Gupta <gupt21@xxxxxxxxx> wrote:
>
> 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@xxxxxxxxx>
> ---
>
> Changes in v3:
> * Removed all direct USB related references
> * Replaced defines with enum
> * Replaced HID_CONNECT_DEFAULT with HID_CONNECT_HIDRAW
> * Removed depends on HIDRAW in Kconfig
> * Used memset wherever possible
> * Emit more clear log - unsupported multi-msg i2c transaction
> * Removed mcp2221 entry from hid-quirk.c
> * Removed module parameter to set i2c bus speed
>
> MAINTAINERS | 7 +
> drivers/hid/Kconfig | 10 +
> drivers/hid/Makefile | 1 +
> drivers/hid/hid-ids.h | 1 +
> drivers/hid/hid-mcp2221.c | 742 ++++++++++++++++++++++++++++++++++++++++++++++
> 5 files changed, 761 insertions(+)
> create mode 100644 drivers/hid/hid-mcp2221.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 141b8d3..bfcdd55 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -10160,6 +10160,13 @@ F: drivers/net/can/m_can/m_can.c
> F: drivers/net/can/m_can/m_can.h
> F: drivers/net/can/m_can/m_can_platform.c
>
> +MCP2221A MICROCHIP USB-HID TO I2C BRIDGE DRIVER
> +M: Rishi Gupta <gupt21@xxxxxxxxx>
> +L: linux-i2c@xxxxxxxxxxxxxxx
> +L: linux-input@xxxxxxxxxxxxxxx
> +S: Maintained
> +F: drivers/hid/hid-mcp2221.c
> +
> MCP4018 AND MCP4531 MICROCHIP DIGITAL POTENTIOMETER DRIVERS
> M: Peter Rosin <peda@xxxxxxxxxx>
> L: linux-iio@xxxxxxxxxxxxxxx
> diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
> index 494a39e..5db6e6a 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 "Microchip MCP2221 HID USB-to-I2C/SMbus host support"
> + depends on USB_HID && I2C
> + ---help---
> + Provides I2C and SMBUS host adapter functionality over USB-HID
> + through MCP2221 device.
> +
> + 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..21052a7 100644
> --- a/drivers/hid/Makefile
> +++ b/drivers/hid/Makefile
> @@ -70,6 +70,7 @@ obj-$(CONFIG_HID_LOGITECH_HIDPP) += hid-logitech-hidpp.o
> obj-$(CONFIG_HID_MACALLY) += hid-macally.o
> obj-$(CONFIG_HID_MAGICMOUSE) += hid-magicmouse.o
> obj-$(CONFIG_HID_MALTRON) += hid-maltron.o
> +obj-$(CONFIG_HID_MCP2221) += hid-mcp2221.o
> obj-$(CONFIG_HID_MAYFLASH) += hid-mf.o
> obj-$(CONFIG_HID_MICROSOFT) += hid-microsoft.o
> obj-$(CONFIG_HID_MONTEREY) += hid-monterey.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..d958475
> --- /dev/null
> +++ b/drivers/hid/hid-mcp2221.c
> @@ -0,0 +1,742 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * MCP2221A - Microchip USB to I2C Host Protocol Bridge
> + *
> + * Copyright (c) 2020, Rishi Gupta <gupt21@xxxxxxxxx>
> + *
> + * 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/hidraw.h>
> +#include <linux/i2c.h>
> +#include "hid-ids.h"
> +
> +/* Commands codes in a raw output report */
> +enum {
> + MCP2221_I2C_WR_DATA = 0x90,
> + MCP2221_I2C_WR_NO_STOP = 0x94,
> + MCP2221_I2C_RD_DATA = 0x91,
> + MCP2221_I2C_RD_RPT_START = 0x93,
> + MCP2221_I2C_GET_DATA = 0x40,
> + MCP2221_I2C_PARAM_OR_STATUS = 0x10,
> + MCP2221_I2C_SET_SPEED = 0x20,
> + MCP2221_I2C_CANCEL = 0x10,
> +};
> +
> +/* Response codes in a raw input report */
> +enum {
> + MCP2221_SUCCESS = 0x00,
> + MCP2221_I2C_ENG_BUSY = 0x01,
> + MCP2221_I2C_START_TOUT = 0x12,
> + MCP2221_I2C_STOP_TOUT = 0x62,
> + MCP2221_I2C_WRADDRL_TOUT = 0x23,
> + MCP2221_I2C_WRDATA_TOUT = 0x44,
> + MCP2221_I2C_WRADDRL_NACK = 0x25,
> + MCP2221_I2C_MASK_ADDR_NACK = 0x40,
> + MCP2221_I2C_WRADDRL_SEND = 0x21,
> + MCP2221_I2C_ADDR_NACK = 0x25,
> + 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 400 kHz. Modify this if you
> + * want to set some other frequency (min 50 kHz - max 400 kHz).
> + */
> +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)
> +{
> + memset(mcp->txbuf, 0, 8);
> + mcp->txbuf[0] = MCP2221_I2C_PARAM_OR_STATUS;
> +
> + 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)
> +{
> + memset(mcp->txbuf, 0, 8);
> + mcp->txbuf[0] = MCP2221_I2C_PARAM_OR_STATUS;
> + mcp->txbuf[2] = MCP2221_I2C_CANCEL;
> +
> + return mcp_send_data_req_status(mcp, mcp->txbuf, 8);
> +}
> +
> +static int mcp_set_i2c_speed(struct mcp2221 *mcp)
> +{
> + int ret;
> +
> + memset(mcp->txbuf, 0, 8);
> + mcp->txbuf[0] = MCP2221_I2C_PARAM_OR_STATUS;
> + mcp->txbuf[3] = MCP2221_I2C_SET_SPEED;
> + mcp->txbuf[4] = mcp->cur_i2c_clk_div;
> +
> + 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, sent;
> +
> + idx = 0;
> + sent = 0;
> + if (msg->len < 60)
> + len = msg->len;
> + else
> + len = 60;
> +
> + do {
> + mcp->txbuf[0] = type;
> + mcp->txbuf[1] = msg->len & 0xff;
> + mcp->txbuf[2] = msg->len >> 8;
> + mcp->txbuf[3] = (u8)(msg->addr << 1);
> +
> + 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);
> +
> + if (last_status) {
> + ret = mcp_chk_last_cmd_status(mcp);
> + if (ret)
> + return ret;
> + }
> +
> + sent = sent + len;
> + if (sent >= msg->len)
> + break;
> +
> + idx = idx + len;
> + if ((msg->len - sent) < 60)
> + len = msg->len - sent;
> + else
> + len = 60;
> +
> + /*
> + * 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);
> + } while (len > 0);
> +
> + 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 {
> + memset(mcp->txbuf, 0, 4);
> + mcp->txbuf[0] = MCP2221_I2C_GET_DATA;
> +
> + 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;
> +
> + usleep_range(980, 1000);
> + } 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 multi-msg i2c transaction\n");
> + ret = -EOPNOTSUPP;
> + }
> + } else {
> + dev_err(&adapter->dev,
> + "unsupported multi-msg i2c transaction\n");
> + 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 + 1; /* 1 is due to command byte itself */
> + mcp->txbuf[2] = 0;
> + mcp->txbuf[3] = (u8)(addr << 1);
> + mcp->txbuf[4] = command;
> +
> + switch (len) {
> + case 0:
> + 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;
> +}
> +
> +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)
> +{
> + 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, 1);
> + if (ret)
> + goto exit;
> +
> + mcp->rxbuf_idx = 0;
> + 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_idx = 0;
> + 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,
> +};
> +
> +/* Gives current state of i2c engine inside mcp2221 */
> +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;
> +
> + 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_HIDRAW);
> + 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 usb-i2c bridge on hidraw%d",
> + ((struct hidraw *)hdev->hidraw)->minor);
> +
> + 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(USB_VENDOR_ID_MICROCHIP, USB_DEVICE_ID_MCP2221) },
> + { }
> +};
> +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);
> +
> +MODULE_AUTHOR("Rishi Gupta <gupt21@xxxxxxxxx>");
> +MODULE_DESCRIPTION("MCP2221 Microchip HID USB to I2C master bridge");
> +MODULE_LICENSE("GPL v2");
> --
> 2.7.4
>

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