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, 10 insertions, 8 deletions

diff --git a/src/soc/broadcom/cygnus/i2c.c b/src/soc/broadcom/cygnus/i2c.c
index fe14000ce9..bc43a8886f 100644
--- a/src/soc/broadcom/cygnus/i2c.c
+++ b/src/soc/broadcom/cygnus/i2c.c
@@ -103,13 +103,14 @@ static void i2c_flush_fifo(struct cygnus_i2c_regs *reg_addr)
 		I2C_MASTER_RX_FIFO_FLUSH | I2C_MASTER_TX_FIFO_FLUSH);
 }
 
-static int i2c_write(struct cygnus_i2c_regs *reg_addr, struct i2c_seg *segment)
+static int i2c_write(struct cygnus_i2c_regs *reg_addr,
+		     struct i2c_msg *segment)
 {
 	uint8_t *data = segment->buf;
 	unsigned int val, status;
 	int i, ret;
 
-	write32(&reg_addr->i2c_master_data_wr, segment->chip << 1);
+	write32(&reg_addr->i2c_master_data_wr, segment->slave << 1);
 
 	for (i = 0; i < segment->len; i++) {
 		val = data[i];
@@ -150,13 +151,13 @@ flush_fifo:
 	return ret;
 }
 
-static int i2c_read(struct cygnus_i2c_regs *reg_addr, struct i2c_seg *segment)
+static int i2c_read(struct cygnus_i2c_regs *reg_addr, struct i2c_msg *segment)
 {
 	uint8_t *data = segment->buf;
 	int i, ret;
 	unsigned int status;
 
-	write32(&reg_addr->i2c_master_data_wr, segment->chip << 1 | 1);
+	write32(&reg_addr->i2c_master_data_wr, segment->slave << 1 | 1);
 
 	/*
 	 * Now we can activate the transfer. Specify the number of bytes to read
@@ -190,7 +191,7 @@ flush_fifo:
 }
 
 static int i2c_do_xfer(struct cygnus_i2c_regs *reg_addr,
-	struct i2c_seg *segment)
+	struct i2c_msg *segment)
 {
 	int ret;
 
@@ -206,7 +207,7 @@ static int i2c_do_xfer(struct cygnus_i2c_regs *reg_addr,
 		return EBUSY;
 	}
 
-	if (segment->read)
+	if (segment->flags & I2C_M_RD)
 		ret = i2c_read(reg_addr, segment);
 	else
 		ret = i2c_write(reg_addr, segment);
@@ -214,12 +215,13 @@ static int i2c_do_xfer(struct cygnus_i2c_regs *reg_addr,
 	return ret;
 }
 
-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 i;
 	int res = 0;
 	struct cygnus_i2c_regs *regs = i2c_bus[bus];
-	struct i2c_seg *seg = segments;
+	struct i2c_msg *seg = segments;
 
 	for (i = 0; i < seg_count; i++, seg++) {
 		res = i2c_do_xfer(regs, seg);