i2c: Move to Linux like `struct i2c_msg`

Our current struct for I2C segments `i2c_seg` was close to being compa-
tible to the Linux version `i2c_msg`, close to being compatible to SMBus
and close to being readable (e.g. what was `chip` supposed to mean?) but
turned out to be hard to fix.

Instead of extending it in a backwards compatible way (and not touching
current controller drivers), replace it with a Linux source compatible
`struct i2c_msg` and patch all the drivers and users with Coccinelle.

The new `struct i2c_msg` should ease porting drivers from Linux and help
to write SMBus compatible controller drivers.

Beside integer type changes, the field `read` is replaced with a generic
field `flags` and `chip` is renamed to `slave`.

Patched with Coccinelle using the clumsy spatch below and some manual
changes:

* Nested struct initializers and one field access skipped by Coccinelle.
* Removed assumption in the code that I2C_M_RD is 1.
* In `i2c.h`, changed all occurences of `chip` to `slave`.

    @@ @@
    -struct i2c_seg
    +struct i2c_msg

    @@ identifier msg; expression e; @@
    (
     struct i2c_msg msg = {
    -    .read = 0,
    +    .flags = 0,
     };
    |
     struct i2c_msg msg = {
    -    .read = 1,
    +    .flags = I2C_M_RD,
     };
    |
     struct i2c_msg msg = {
    -    .chip = e,
    +    .slave = e,
     };
    )

    @@ struct i2c_msg msg; statement S1, S2; @@
    (
    -if (msg.read)
    +if (msg.flags & I2C_M_RD)
     S1 else S2
    |
    -if (msg.read)
    +if (msg.flags & I2C_M_RD)
     S1
    )

    @@ struct i2c_msg *msg; statement S1, S2; @@
    (
    -if (msg->read)
    +if (msg->flags & I2C_M_RD)
     S1 else S2
    |
    -if (msg->read)
    +if (msg->flags & I2C_M_RD)
     S1
    )

    @@ struct i2c_msg msg; expression e; @@
    (
    -msg.read = 0;
    +msg.flags = 0;
    |
    -msg.read = 1;
    +msg.flags = I2C_M_RD;
    |
    -msg.read = e;
    +msg.flags = e ? I2C_M_RD : 0;
    |
    -!!(msg.read)
    +(msg.flags & I2C_M_RD)
    |
    -(msg.read)
    +(msg.flags & I2C_M_RD)
    )

    @@ struct i2c_msg *msg; expression e; @@
    (
    -msg->read = 0;
    +msg->flags = 0;
    |
    -msg->read = 1;
    +msg->flags = I2C_M_RD;
    |
    -msg->read = e;
    +msg->flags = e ? I2C_M_RD : 0;
    |
    -!!(msg->read)
    +(msg->flags & I2C_M_RD)
    |
    -(msg->read)
    +(msg->flags & I2C_M_RD)
    )

    @@ struct i2c_msg msg; @@
    -msg.chip
    +msg.slave

    @@ struct i2c_msg *msg; expression e; @@
    -msg[e].chip
    +msg[e].slave

    @ slave disable ptr_to_array @ struct i2c_msg *msg; @@
    -msg->chip
    +msg->slave

Change-Id: Ifd7cabf0a18ffd7a1def25d1d7059b713d0b7ea9
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/20542
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>

2 files changed, 6 insertions, 5 deletions

diff --git a/src/device/i2c.c b/src/device/i2c.c
index d4670a013c..67470d4921 100644
--- a/src/device/i2c.c
+++ b/src/device/i2c.c
@@ -49,7 +49,7 @@ int i2c_dev_find_bus(struct device *dev)
 	return ops->dev_to_bus(pbus->dev);
 }
 
-int i2c_dev_transfer(struct device *dev, struct i2c_seg *segments, int count)
+int i2c_dev_transfer(struct device *dev, struct i2c_msg *segments, int count)
 {
 	int bus = i2c_dev_find_bus(dev);
 	if (bus < 0)
diff --git a/src/device/software_i2c.c b/src/device/software_i2c.c
index be7aebecd0..368d145b3e 100644
--- a/src/device/software_i2c.c
+++ b/src/device/software_i2c.c
@@ -238,19 +238,20 @@ static int in_byte(unsigned bus, int ack)
 	return byte;
 }
 
-int software_i2c_transfer(unsigned bus, struct i2c_seg *segments, int count)
+int software_i2c_transfer(unsigned bus, struct i2c_msg *segments, int count)
 {
 	int i;
-	struct i2c_seg *seg;
+	struct i2c_msg *seg;
 
 	for (seg = segments; seg - segments < count; seg++) {
 		if (start_cond(bus) < 0)
 			return -1;
-		if (out_byte(bus, seg->chip << 1 | !!seg->read) < 0)
+		const u8 addr_dir = seg->slave << 1 | !!(seg->flags & I2C_M_RD);
+		if (out_byte(bus, addr_dir) < 0)
 			return -1;
 		for (i = 0; i < seg->len; i++) {
 			int ret;
-			if (seg->read) {
+			if (seg->flags & I2C_M_RD) {
 				ret = in_byte(bus, i < seg->len - 1);
 				seg->buf[i] = (u8)ret;
 			} else {