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>

1 files changed, 14 insertions, 9 deletions

diff --git a/src/soc/mediatek/mt8173/i2c.c b/src/soc/mediatek/mt8173/i2c.c
index f07ffc92ab..1d541e5d0f 100644
--- a/src/soc/mediatek/mt8173/i2c.c
+++ b/src/soc/mediatek/mt8173/i2c.c
@@ -136,7 +136,7 @@ static inline void mtk_i2c_dump_info(uint8_t bus)
 	I2CLOG("addr address %x\n", (uint32_t)regs);
 }
 
-static uint32_t mtk_i2c_transfer(uint8_t bus, struct i2c_seg *seg,
+static uint32_t mtk_i2c_transfer(uint8_t bus, struct i2c_msg *seg,
 				 enum i2c_modes read)
 {
 	uint32_t ret_code = I2C_OK;
@@ -154,7 +154,7 @@ static uint32_t mtk_i2c_transfer(uint8_t bus, struct i2c_seg *seg,
 	regs = i2c[bus].i2c_regs;
 	dma_regs = i2c[bus].i2c_dma_regs;
 
-	addr = seg[0].chip;
+	addr = seg[0].slave;
 
 	switch (read) {
 	case I2C_WRITE_MODE:
@@ -305,26 +305,31 @@ static uint32_t mtk_i2c_transfer(uint8_t bus, struct i2c_seg *seg,
 	return ret_code;
 }
 
-static uint8_t mtk_i2c_should_combine(struct i2c_seg *seg, int left_count)
+static uint8_t mtk_i2c_should_combine(struct i2c_msg *seg, int left_count)
 {
-	if (left_count >= 2 && seg[0].read == 0 && seg[1].read == 1 &&
-	    seg[0].chip == seg[1].chip)
+	if (left_count >= 2 &&
+	    !(seg[0].flags & I2C_M_RD) &&
+	    (seg[1].flags & I2C_M_RD) &&
+	    seg[0].slave == seg[1].slave)
 		return 1;
 	else
 		return 0;
 }
 
-int platform_i2c_transfer(unsigned bus, struct i2c_seg *segments, int seg_count)
+int platform_i2c_transfer(unsigned bus, struct i2c_msg *segments,
+			  int seg_count)
 {
 	int ret = 0;
 	int i;
 	int read;
 
 	for (i = 0; i < seg_count; i++) {
-		if (mtk_i2c_should_combine(&segments[i], seg_count - i))
+		if (mtk_i2c_should_combine(&segments[i], seg_count - i)) {
 			read = I2C_WRITE_READ_MODE;
-		else
-			read = segments[i].read;
+		} else {
+			read = (segments[i].flags & I2C_M_RD) ?
+				I2C_READ_MODE : I2C_WRITE_MODE;
+		}
 
 		ret = mtk_i2c_transfer(bus, &segments[i], read);