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From:   rishi gupta <gupt21@gmail.com>
Date:   Mon, 2 Mar 2020 14:08:44 +0530
Message-ID: <CALUj-guUrJ8meHW3N=idbCcy3DnhNpFxki1uF=mVdsTb=xAVTg@mail.gmail.com>
Subject: Re: [PATCH v3] HID: mcp2221: add usb to i2c-smbus host bridge
To:     Jiri Kosina <jikos@kernel.org>,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>,
        wsa+renesas@sang-engineering.com
Cc:     Greg KH <gregkh@linuxfoundation.org>,
        Linux I2C <linux-i2c@vger.kernel.org>,
        "open list:HID CORE LAYER" <linux-input@vger.kernel.org>,
        lkml <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Gentle ping...

Regards,
Rishi


On Mon, Feb 10, 2020 at 7:20 PM rishi gupta <gupt21@gmail.com> wrote:
>
> 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@gmail.com> 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@gmail.com>
> > ---
> >
> > 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@gmail.com>
> > +L:     linux-i2c@vger.kernel.org
> > +L:     linux-input@vger.kernel.org
> > +S:     Maintained
> > +F:     drivers/hid/hid-mcp2221.c
> > +
> >  MCP4018 AND MCP4531 MICROCHIP DIGITAL POTENTIOMETER DRIVERS
> >  M:     Peter Rosin <peda@axentia.se>
> >  L:     linux-iio@vger.kernel.org
> > 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@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/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@gmail.com>");
> > +MODULE_DESCRIPTION("MCP2221 Microchip HID USB to I2C master bridge");
> > +MODULE_LICENSE("GPL v2");
> > --
> > 2.7.4
> >