HID: cp2112: add I2C mode

cp2112 supports single I2C read/write transactions.  It can't combine I2C
transactions.

Add master_xfer, using similar code flow as for smbus_xfer.

Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 102 insertions, 1 deletions

diff --git a/drivers/hid/hid-cp2112.c b/drivers/hid/hid-cp2112.c
index 3952d90723b9..a822db5a8338 100644
--- a/drivers/hid/hid-cp2112.c
+++ b/drivers/hid/hid-cp2112.c
@@ -429,6 +429,105 @@ static int cp2112_write_req(void *buf, u8 slave_address, u8 command, u8 *data,
         return data_length + 4;
 }
 
+static int cp2112_i2c_write_req(void *buf, u8 slave_address, u8 *data,
+                                u8 data_length)
+{
+        struct cp2112_write_req_report *report = buf;
+
+        if (data_length > sizeof(report->data))
+                return -EINVAL;
+
+        report->report = CP2112_DATA_WRITE_REQUEST;
+        report->slave_address = slave_address << 1;
+        report->length = data_length;
+        memcpy(report->data, data, data_length);
+        return data_length + 3;
+}
+
+static int cp2112_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
+                           int num)
+{
+        struct cp2112_device *dev = (struct cp2112_device *)adap->algo_data;
+        struct hid_device *hdev = dev->hdev;
+        u8 buf[64];
+        ssize_t count;
+        unsigned int retries;
+        int ret;
+
+        hid_dbg(hdev, "I2C %d messages\n", num);
+
+        if (num != 1) {
+                hid_err(hdev,
+                        "Multi-message I2C transactions not supported\n");
+                return -EOPNOTSUPP;
+        }
+
+        if (msgs->flags & I2C_M_RD)
+                count = cp2112_read_req(buf, msgs->addr, msgs->len);
+        else
+                count = cp2112_i2c_write_req(buf, msgs->addr, msgs->buf,
+                                             msgs->len);
+
+        if (count < 0)
+                return count;
+
+        ret = hid_hw_power(hdev, PM_HINT_FULLON);
+        if (ret < 0) {
+                hid_err(hdev, "power management error: %d\n", ret);
+                return ret;
+        }
+
+        ret = cp2112_hid_output(hdev, buf, count, HID_OUTPUT_REPORT);
+        if (ret < 0) {
+                hid_warn(hdev, "Error starting transaction: %d\n", ret);
+                goto power_normal;
+        }
+
+        for (retries = 0; retries < XFER_STATUS_RETRIES; ++retries) {
+                ret = cp2112_xfer_status(dev);
+                if (-EBUSY == ret)
+                        continue;
+                if (ret < 0)
+                        goto power_normal;
+                break;
+        }
+
+        if (XFER_STATUS_RETRIES <= retries) {
+                hid_warn(hdev, "Transfer timed out, cancelling.\n");
+                buf[0] = CP2112_CANCEL_TRANSFER;
+                buf[1] = 0x01;
+
+                ret = cp2112_hid_output(hdev, buf, 2, HID_OUTPUT_REPORT);
+                if (ret < 0)
+                        hid_warn(hdev, "Error cancelling transaction: %d\n",
+                                 ret);
+
+                ret = -ETIMEDOUT;
+                goto power_normal;
+        }
+
+        if (!(msgs->flags & I2C_M_RD))
+                goto finish;
+
+        ret = cp2112_read(dev, msgs->buf, msgs->len);
+        if (ret < 0)
+                goto power_normal;
+        if (ret != msgs->len) {
+                hid_warn(hdev, "short read: %d < %d\n", ret, msgs->len);
+                ret = -EIO;
+                goto power_normal;
+        }
+
+finish:
+        /* return the number of transferred messages */
+        ret = 1;
+
+power_normal:
+        hid_hw_power(hdev, PM_HINT_NORMAL);
+        hid_dbg(hdev, "I2C transfer finished: %d\n", ret);
+        return ret;
+}
+
 static int cp2112_xfer(struct i2c_adapter *adap, u16 addr,
                        unsigned short flags, char read_write, u8 command,
                        int size, union i2c_smbus_data *data)
@@ -595,7 +694,8 @@ power_normal:
 
 static u32 cp2112_functionality(struct i2c_adapter *adap)
 {
-        return I2C_FUNC_SMBUS_BYTE |
+        return I2C_FUNC_I2C |
+                I2C_FUNC_SMBUS_BYTE |
                 I2C_FUNC_SMBUS_BYTE_DATA |
                 I2C_FUNC_SMBUS_WORD_DATA |
                 I2C_FUNC_SMBUS_BLOCK_DATA |
@@ -605,6 +705,7 @@ static u32 cp2112_functionality(struct i2c_adapter *adap)
 }
 
 static const struct i2c_algorithm smbus_algorithm = {
+        .master_xfer    = cp2112_i2c_xfer,
         .smbus_xfer     = cp2112_xfer,
         .functionality  = cp2112_functionality,
 };