i2c: Split i2c_xfer into locked/unlocked versions.

Rename i2c_xfer to i2c_xfer_unlocked.  Audit all users of i2c_xfer to
see if they can use simple locking semantics or require their own
locking.  Since locked accesses are only safe for I2C_XFER_SINGLE
transactions, remove the flags parameter from i2c_xfer.  This also makes
the audit a bit easier.

Some remaining applications hold the bus locked across several
transactions that would otherwise be atomic, and a few others implement
complex I2C transactions in multiple commands.

Add a (nondeterministic) verification on the I2C port locking
correctness.  This will catch all statically incorrect locking patterns,
although dynamically incorrect locking patterns may not be caught.
Related: Revise the i2c_port_active_count to be a bitmap of the active
ports instead of a count of the active ports.  The EC's mutex does not
provide an is_locked() primitive, and we would prefer not to have one.

- board/glados: Custom locking for battery reset
- board/mchpevb1: Custom locking for battery reset
- board/oak: Custom locking for battery reset
- board/samus: Custom locking for lightbar reset
- board/sweetberry: simple locking
- board/servo_micro: Custom locking for funky i2c transfers
- capsense: simple locking
- host_command_master: multi-command transactions
- lb_common: manual locking to support samus power sequence
- smbus: multi-command transactions
- usb_i2c: simple locking
- driver/tcpm/fusb302: simple locking and multi-command transactions
- driver/tcpm/tcpi: Forward _unlocked and implicitly locked interface to
  fusb302
- driver/touchpad_elan: simple locking

BUG=chromium:871851
BRANCH=none
TEST=buildall; very careful audit
TEST=grunt clamshell and Coral clamshell, test boot, battery charging,
PD communication, and TCPC port low-power mode.
Signed-off-by: Jonathan Brandmeyer <jbrandmeyer@chromium.org>

Change-Id: Ieabf22bcab42780bdb994fca3ced5d8c62519d56
Reviewed-on: https://chromium-review.googlesource.com/1169913
Commit-Ready: Jonathan Brandmeyer <jbrandmeyer@chromium.org>
Tested-by: Jonathan Brandmeyer <jbrandmeyer@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Jett Rink <jettrink@chromium.org>

6 files changed, 13 insertions, 14 deletions

diff --git a/board/glados/battery.c b/board/glados/battery.c
index 2372affb64..016d225950 100644
--- a/board/glados/battery.c
+++ b/board/glados/battery.c
@@ -47,9 +47,9 @@ int board_cut_off_battery(void)
 	buf[2] = PARAM_CUT_OFF_HIGH;
 
 	i2c_lock(I2C_PORT_BATTERY, 1);
-	rv = i2c_xfer(I2C_PORT_BATTERY, BATTERY_ADDR, buf, 3, NULL, 0,
+	rv = i2c_xfer_unlocked(I2C_PORT_BATTERY, BATTERY_ADDR, buf, 3, NULL, 0,
 		      I2C_XFER_SINGLE);
-	rv |= i2c_xfer(I2C_PORT_BATTERY, BATTERY_ADDR, buf, 3, NULL, 0,
+	rv |= i2c_xfer_unlocked(I2C_PORT_BATTERY, BATTERY_ADDR, buf, 3, NULL, 0,
 		       I2C_XFER_SINGLE);
 	i2c_lock(I2C_PORT_BATTERY, 0);
 
diff --git a/board/mchpevb1/battery.c b/board/mchpevb1/battery.c
index 2372affb64..016d225950 100644
--- a/board/mchpevb1/battery.c
+++ b/board/mchpevb1/battery.c
@@ -47,9 +47,9 @@ int board_cut_off_battery(void)
 	buf[2] = PARAM_CUT_OFF_HIGH;
 
 	i2c_lock(I2C_PORT_BATTERY, 1);
-	rv = i2c_xfer(I2C_PORT_BATTERY, BATTERY_ADDR, buf, 3, NULL, 0,
+	rv = i2c_xfer_unlocked(I2C_PORT_BATTERY, BATTERY_ADDR, buf, 3, NULL, 0,
 		      I2C_XFER_SINGLE);
-	rv |= i2c_xfer(I2C_PORT_BATTERY, BATTERY_ADDR, buf, 3, NULL, 0,
+	rv |= i2c_xfer_unlocked(I2C_PORT_BATTERY, BATTERY_ADDR, buf, 3, NULL, 0,
 		       I2C_XFER_SINGLE);
 	i2c_lock(I2C_PORT_BATTERY, 0);
 
diff --git a/board/oak/battery.c b/board/oak/battery.c
index a3fe0cd452..a868e20bc0 100644
--- a/board/oak/battery.c
+++ b/board/oak/battery.c
@@ -57,9 +57,9 @@ static int cutoff(void)
 	buf[2] = PARAM_CUT_OFF_HIGH;
 
 	i2c_lock(I2C_PORT_BATTERY, 1);
-	rv = i2c_xfer(I2C_PORT_BATTERY, BATTERY_ADDR, buf, 3, NULL, 0,
+	rv = i2c_xfer_unlocked(I2C_PORT_BATTERY, BATTERY_ADDR, buf, 3, NULL, 0,
 		      I2C_XFER_SINGLE);
-	rv |= i2c_xfer(I2C_PORT_BATTERY, BATTERY_ADDR, buf, 3, NULL, 0,
+	rv |= i2c_xfer_unlocked(I2C_PORT_BATTERY, BATTERY_ADDR, buf, 3, NULL, 0,
 		       I2C_XFER_SINGLE);
 	i2c_lock(I2C_PORT_BATTERY, 0);
 
diff --git a/board/samus/battery.c b/board/samus/battery.c
index 64cf417ecc..f3c78e9d96 100644
--- a/board/samus/battery.c
+++ b/board/samus/battery.c
@@ -290,9 +290,9 @@ int board_cut_off_battery(void)
 	buf[2] = PARAM_CUT_OFF_HIGH;
 
 	i2c_lock(I2C_PORT_BATTERY, 1);
-	rv = i2c_xfer(I2C_PORT_BATTERY, BATTERY_ADDR, buf, 3, NULL, 0,
+	rv = i2c_xfer_unlocked(I2C_PORT_BATTERY, BATTERY_ADDR, buf, 3, NULL, 0,
 		      I2C_XFER_SINGLE);
-	rv |= i2c_xfer(I2C_PORT_BATTERY, BATTERY_ADDR, buf, 3, NULL, 0,
+	rv |= i2c_xfer_unlocked(I2C_PORT_BATTERY, BATTERY_ADDR, buf, 3, NULL, 0,
 		      I2C_XFER_SINGLE);
 	i2c_lock(I2C_PORT_BATTERY, 0);
 
diff --git a/board/servo_micro/board.c b/board/servo_micro/board.c
index 5887d559ae..355c091a77 100644
--- a/board/servo_micro/board.c
+++ b/board/servo_micro/board.c
@@ -231,12 +231,13 @@ static int ite_i2c_read_register(uint8_t register_offset, uint8_t *output)
 	 */
 	int ret;
 	/* Tell the ITE EC which register we want to read. */
-	ret = i2c_xfer(I2C_PORT_MASTER, ITE_DFU_I2C_CMD_ADDR, &register_offset,
-		sizeof(register_offset), NULL, 0, I2C_XFER_SINGLE);
+	ret = i2c_xfer_unlocked(I2C_PORT_MASTER, ITE_DFU_I2C_CMD_ADDR,
+		&register_offset, sizeof(register_offset),
+		NULL, 0, I2C_XFER_SINGLE);
 	if (ret != EC_SUCCESS)
 		return ret;
 	/* Read in the 1 byte register value. */
-	ret = i2c_xfer(I2C_PORT_MASTER, ITE_DFU_I2C_DATA_ADDR, NULL, 0,
+	ret = i2c_xfer_unlocked(I2C_PORT_MASTER, ITE_DFU_I2C_DATA_ADDR, NULL, 0,
 		output, sizeof(*output), I2C_XFER_SINGLE);
 	return ret;
 }
diff --git a/board/sweetberry/board.c b/board/sweetberry/board.c
index 8640cfd87f..2d94f06f76 100644
--- a/board/sweetberry/board.c
+++ b/board/sweetberry/board.c
@@ -121,8 +121,6 @@ static void board_init(void)
 	uint8_t tmp;
 
 	/* i2c 0 has a tendancy to get wedged. TODO(nsanders): why? */
-	i2c_lock(0, 1);
-	i2c_xfer(0, 0, NULL, 0, &tmp, 1, I2C_XFER_SINGLE);
-	i2c_lock(0, 0);
+	i2c_xfer(0, 0, NULL, 0, &tmp, 1);
 }
 DECLARE_HOOK(HOOK_INIT, board_init, HOOK_PRIO_DEFAULT);