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 <ellen@xxxxxxxxxxxxxxxxxxx>
---
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-input" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
