i2c-bcm2835: Implement I2C_M_IGNORE_NAK

Now that transfers aren't aborted immediately (and uncleanly) on
errors, and the FIFOs are always drained after all transfers, we
can implement I2C_M_IGNORE_NAK by ignoring the returned error
value.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>

diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c
index cc78e99..71a74de 100644 (file)
--- a/drivers/i2c/busses/i2c-bcm2835.c
+++ b/drivers/i2c/busses/i2c-bcm2835.c
@@ -443,6 +443,7 @@ static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 {
        struct bcm2835_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
        unsigned long time_left;
+       bool ignore_nak = false;
        int i;
 
        if (debug)
@@ -452,12 +453,15 @@ static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
                for (i = 0; i < num; i++)
                        bcm2835_debug_print_msg(i2c_dev, &msgs[i], i + 1, num, __func__);
 
-       for (i = 0; i < (num - 1); i++)
+       for (i = 0; i < (num - 1); i++) {
                if (msgs[i].flags & I2C_M_RD) {
                        dev_warn_once(i2c_dev->dev,
                                      "only one read message supported, has to be last\n");
                        return -EOPNOTSUPP;
                }
+               if (msgs[i].flags & I2C_M_IGNORE_NAK)
+                       ignore_nak = true;
+       }
 
        i2c_dev->curr_msg = msgs;
        i2c_dev->num_msgs = num;
@@ -471,6 +475,9 @@ static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 
        bcm2835_i2c_finish_transfer(i2c_dev);
 
+       if (ignore_nak)
+               i2c_dev->msg_err &= ~BCM2835_I2C_S_ERR;
+
        if (debug > 1 || (debug && (!time_left || i2c_dev->msg_err)))
                bcm2835_debug_print(i2c_dev);
        i2c_dev->debug_num_msgs = 0;
@@ -497,7 +504,7 @@ static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 
 static u32 bcm2835_i2c_func(struct i2c_adapter *adap)
 {
-       return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+       return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
 }
 
 static const struct i2c_algorithm bcm2835_i2c_algo = {