diff options
| author | Sifan Naeem <sifan.naeem@imgtec.com> | 2015-11-19 09:35:13 +0000 |
|---|---|---|
| committer | Wolfram Sang <wsa@the-dreams.de> | 2016-01-02 22:03:39 +0100 |
| commit | c55ebe0e72737dd3d49f6fa3156313e1cab5dcab (patch) | |
| tree | d70021f8e4abd2c2d83cfec35156d674fe26ca95 /drivers/i2c/busses/i2c-img-scb.c | |
| parent | 54177ccfbe95fcf250a89508a705bfe4706e3b86 (diff) | |
| download | linux-c55ebe0e72737dd3d49f6fa3156313e1cab5dcab.tar.bz2 | |
i2c: img-scb: support I2C_M_IGNORE_NAK
This commit adds support for the I2C_M_IGNORE_NAK protocol
modification.
Such behaviour can only be implemented in atomic mode. So, if a
transaction contains a message with such flag the drivers
switches to atomic mode. The implementation consists simply in
treating NAKs as ACKs.
Signed-off-by: Sifan Naeem <sifan.naeem@imgtec.com>
Acked-by: James Hogan <james.hogan@imgtec.com>
Reviewed-by: James Hartley <james.hartley@imgtec.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c/busses/i2c-img-scb.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-img-scb.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/drivers/i2c/busses/i2c-img-scb.c b/drivers/i2c/busses/i2c-img-scb.c index 3795fe130ef2..c92bcf7c204f 100644 --- a/drivers/i2c/busses/i2c-img-scb.c +++ b/drivers/i2c/busses/i2c-img-scb.c @@ -750,7 +750,9 @@ static unsigned int img_i2c_atomic(struct img_i2c *i2c, next_cmd = CMD_RET_ACK; break; case CMD_RET_ACK: - if (i2c->line_status & LINESTAT_ACK_DET) { + if (i2c->line_status & LINESTAT_ACK_DET || + (i2c->line_status & LINESTAT_NACK_DET && + i2c->msg.flags & I2C_M_IGNORE_NAK)) { if (i2c->msg.len == 0) { next_cmd = CMD_GEN_STOP; } else if (i2c->msg.flags & I2C_M_RD) { @@ -1017,20 +1019,23 @@ static int img_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, return -EIO; for (i = 0; i < num; i++) { - if (likely(msgs[i].len)) - continue; /* * 0 byte reads are not possible because the slave could try * and pull the data line low, preventing a stop bit. */ - if (unlikely(msgs[i].flags & I2C_M_RD)) + if (!msgs[i].len && msgs[i].flags & I2C_M_RD) return -EIO; /* * 0 byte writes are possible and used for probing, but we * cannot do them in automatic mode, so use atomic mode * instead. + * + * Also, the I2C_M_IGNORE_NAK mode can only be implemented + * in atomic mode. */ - atomic = true; + if (!msgs[i].len || + (msgs[i].flags & I2C_M_IGNORE_NAK)) + atomic = true; } ret = clk_prepare_enable(i2c->scb_clk); |