[PATCH 7/7] qi-fix-i2c-multiread-nack-nak.patch

[Andy Green]

On the last read, master must NAK, on intermediate reads it must ACK.
If you get this wrong, communication with device is screwed even in Linux.

Signed-off-by: Andy Green <[EMAIL PROTECTED]>
---

 src/drivers/i2c-bitbang.c |   29 +++++++++++++++++++++++------
 1 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/src/drivers/i2c-bitbang.c b/src/drivers/i2c-bitbang.c
index eef28a6..436003e 100644
--- a/src/drivers/i2c-bitbang.c
+++ b/src/drivers/i2c-bitbang.c
@@ -53,14 +53,17 @@ int i2c_next_state(struct i2c_bitbang * bb)
        case IBS_INIT:
                bb->index = 0;
                bb->index_read = 0;
-               /* fall thru */
+               (bb->set)(1, 1);
+               bb->state = IBS_START1;
+               break;
+
        case IBS_START1:
                (bb->set)(1, 0);
-               (bb->set)(0, 0); /* start */
                bb->state = IBS_START2;
                break;
 
        case IBS_START2:
+               (bb->set)(0, 0); /* start */
                bb->count = 8;
                bb->state = IBS_ADS_TX_S;
                break;
@@ -137,25 +140,34 @@ int i2c_next_state(struct i2c_bitbang * bb)
        case IBS_DATA_RX_L:
                bb->data[bb->index_read] <<= 1;
                bb->data[bb->index_read] |= !!(bb->read_sda)();
-               (bb->set)(0, 1);
                bb->count--;
                if (bb->count) {
+                       (bb->set)(0, 1);
                        bb->state = IBS_DATA_RX_S;
                        break;
                }
 
                /* slave has released SDA now, bang down ACK */
-               (bb->set)(0, 0);
+               if (bb->data[bb->index + 1] != IBCONTROL_DO_READ)
+                       (bb->set)(0, 1);
+               else
+                       (bb->set)(0, 0);
                bb->state = IBS_DATA_RX_ACK_H;
                break;
 
        case IBS_DATA_RX_ACK_H:
-               (bb->set)(1, 0);
+               if (bb->data[bb->index + 1] != IBCONTROL_DO_READ)
+                       (bb->set)(1, 1); /* NAK */
+               else
+                       (bb->set)(1, 0); /* ACK */
                bb->state = IBS_DATA_RX_ACK_L;
                break;
 
        case IBS_DATA_RX_ACK_L:
-               (bb->set)(0, 1);
+               if (bb->data[bb->index + 1] != IBCONTROL_DO_READ)
+                       (bb->set)(0, 1); /* NAK */
+               else
+                       (bb->set)(0, 0); /* ACK */
                bb->index_read++;
                bb->index++;
                switch (bb->data[bb->index]) {
@@ -214,6 +226,11 @@ static int i2c_complete_synchronously(struct i2c_bitbang * 
bb)
                (bb->spin)();
        }
 
+       if (ret < 0) {
+               puts("i2c transaction failed ");
+               printdec(ret);
+               puts("\n");
+       }
        return ret;
 }