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authorSifan Naeem <sifan.naeem@imgtec.com>2015-11-19 09:35:13 +0000
committerWolfram Sang <wsa@the-dreams.de>2016-01-02 22:03:39 +0100
commitc55ebe0e72737dd3d49f6fa3156313e1cab5dcab (patch)
treed70021f8e4abd2c2d83cfec35156d674fe26ca95 /drivers/i2c
parent54177ccfbe95fcf250a89508a705bfe4706e3b86 (diff)
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')
-rw-r--r--drivers/i2c/busses/i2c-img-scb.c15
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);