cp2112_i2c_xfer() only supports a single i2c_msg and only reads up to 61 bytes. More than one message at a time and longers reads just return errors.
This is a serious limitation. For example, the at24 eeprom driver generates paired write and read messages (for eeprom address and data). And the reads can be quite large. The fix consists of a loop to go through all the messages, and a loop around cp2112_read() to pick up all the returned data. For extra credit, it now also supports write-read pairs and implements them as CP2112_DATA_WRITE_READ_REQUEST. Signed-off-by: Ellen Wang <[email protected]> --- drivers/hid/hid-cp2112.c | 136 +++++++++++++++++++++++++++++----------------- 1 file changed, 87 insertions(+), 49 deletions(-) diff --git a/drivers/hid/hid-cp2112.c b/drivers/hid/hid-cp2112.c index 3318de6..e7e72a4 100644 --- a/drivers/hid/hid-cp2112.c +++ b/drivers/hid/hid-cp2112.c @@ -444,11 +444,30 @@ static int cp2112_i2c_write_req(void *buf, u8 slave_address, u8 *data, return data_length + 3; } +static int cp2112_i2c_write_read_req(void *buf, u8 slave_address, + u8 *addr, int addr_length, + int read_length) +{ + struct cp2112_write_read_req_report *report = buf; + + if (read_length < 1 || read_length > 512 || + addr_length > sizeof(report->target_address)) + return -EINVAL; + + report->report = CP2112_DATA_WRITE_READ_REQUEST; + report->slave_address = slave_address << 1; + report->length = cpu_to_be16(read_length); + report->target_address_length = addr_length; + memcpy(report->target_address, addr, addr_length); + return addr_length + 5; +} + 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; + struct i2c_msg *m; u8 buf[64]; ssize_t count; unsigned int retries; @@ -456,71 +475,90 @@ static int cp2112_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, 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 (m = msgs; m < msgs + num; m++) { + /* + * If the top two messages are a write followed by a read, + * then we do them together as CP2112_DATA_WRITE_READ_REQUEST. + * Otherwise, process one message. + */ + + if (m + 1 < msgs + num && m[0].addr == m[1].addr && + !(m[0].flags & I2C_M_RD) && (m[1].flags & I2C_M_RD)) { + hid_dbg(hdev, "I2C msg %zd write-read %#04x wlen %d rlen %d\n", + m - msgs, m[0].addr, m[0].len, m[1].len); + count = cp2112_i2c_write_read_req(buf, m[0].addr, + m[0].buf, m[0].len, m[1].len); + m++; + } else if (m->flags & I2C_M_RD) { + hid_dbg(hdev, "I2C msg %zd read %#04x len %d\n", + m - msgs, m->addr, m->len); + count = cp2112_read_req(buf, m->addr, m->len); + } else { + hid_dbg(hdev, "I2C msg %zd write %#04x len %d\n", + m - msgs, m->addr, m->len); + count = cp2112_i2c_write_req(buf, m->addr, m->buf, + m->len); + } - for (retries = 0; retries < XFER_STATUS_RETRIES; ++retries) { - ret = cp2112_xfer_status(dev); - if (-EBUSY == ret) - continue; - if (ret < 0) + if (count < 0) { + ret = count; 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, count, HID_OUTPUT_REPORT); + if (ret < 0) { + hid_warn(hdev, "Error starting transaction: %d\n", ret); + goto power_normal; + } - ret = cp2112_hid_output(hdev, buf, 2, HID_OUTPUT_REPORT); - if (ret < 0) - hid_warn(hdev, "Error cancelling transaction: %d\n", - ret); + for (retries = 0; retries < XFER_STATUS_RETRIES; ++retries) { + ret = cp2112_xfer_status(dev); + if (-EBUSY == ret) + continue; + if (ret < 0) + goto power_normal; + break; + } - ret = -ETIMEDOUT; - goto power_normal; - } + if (XFER_STATUS_RETRIES <= retries) { + hid_warn(hdev, "Transfer timed out, cancelling.\n"); + buf[0] = CP2112_CANCEL_TRANSFER; + buf[1] = 0x01; - if (!(msgs->flags & I2C_M_RD)) - goto finish; + ret = cp2112_hid_output(hdev, buf, 2, + HID_OUTPUT_REPORT); + if (ret < 0) + hid_warn(hdev, + "Error cancelling transaction: %d\n", + ret); - 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; + ret = -ETIMEDOUT; + goto power_normal; + } + + if (!(m->flags & I2C_M_RD)) + continue; + + for (count = 0; count < m->len;) { + ret = cp2112_read(dev, m->buf + count, m->len - count); + if (ret < 0) + goto power_normal; + count += ret; + if (count > m->len) { + hid_warn(hdev, "long read: %d > %zd\n", + ret, m->len - count + ret); + } + } } -finish: /* return the number of transferred messages */ - ret = 1; + ret = num; power_normal: hid_hw_power(hdev, PM_HINT_NORMAL); -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
