usb_i2c: Fail if board I2C bridge is disabled

Add usb_i2c_board_is_enabled().

On Cr50, this is now also connected to the I2C CCD capability.  The
USB-I2C bridge can only be used when the capability is available.

On other platforms (Servo V4, etc.) where usb_i2c_board_enable() is
a no-op, add a dummy implementation which always returns true.

See go/cr50-ccd-wp for more information.

BUG=b:62537474
BRANCH=cr50
TEST=manual with CR50_DEV=1
	Connect host PC to dev board USB port
	On host PC:
		sudo servod -c ccd_cr50.xml -c reef_r1_inas.xml
		dut-control pp3300_ec_shv_reg --> fail, error 0x8001

	ccdoops --> reset I2C config
	ccd i2c disable --> I2C disabled

	On host PC:
		sudo servod -c ccd_cr50.xml -c reef_r1_inas.xml
		dut-control pp3300_ec_shv_reg --> fail, error 0x0006

	ccd i2c enable --> I2C enabled
	ccdunlock --> I2C disabled
	ccdoops --> I2C enabled
	ccdset i2c unlesslocked
	ccdlock --> I2C disabled
	ccdunlock --> I2C enabled

Change-Id: Ia3df32e239a5f7c5915bc6c7e408ce0dc8b26c89
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/590577
Reviewed-by: Aseda Aboagye <aaboagye@chromium.org>
Reviewed-by: Mary Ruthven <mruthven@chromium.org>

2 files changed, 39 insertions, 3 deletions

diff --git a/board/cr50/rdd.c b/board/cr50/rdd.c
index 622bd8f986..bf5a3ed8f0 100644
--- a/board/cr50/rdd.c
+++ b/board/cr50/rdd.c
@@ -289,6 +289,8 @@ static int command_ccd(int argc, char **argv)
 	ccprintf("AP UART:  %s\nEC UART:  %s\n",
 		uart_tx_is_connected(UART_AP) ? " enabled" : "disabled",
 		uart_tx_is_connected(UART_EC) ? " enabled" : "disabled");
+	ccprintf("I2C:      %s\n",
+		 usb_i2c_board_is_enabled() ? " enabled" : "disabled");
 
 	return EC_SUCCESS;
 }
diff --git a/board/cr50/usb_i2c.c b/board/cr50/usb_i2c.c
index 24a6fbdea6..0bc5b3f215 100644
--- a/board/cr50/usb_i2c.c
+++ b/board/cr50/usb_i2c.c
@@ -3,6 +3,7 @@
  * found in the LICENSE file.
  */
 
+#include "case_closed_debug.h"
 #include "console.h"
 #include "device_state.h"
 #include "gpio.h"
@@ -16,7 +17,7 @@
 
 #define CPRINTS(format, args...) cprints(CC_USB, format, ## args)
 
-static int i2c_enabled(void)
+int usb_i2c_board_is_enabled(void)
 {
 	return !gpio_get_level(GPIO_EN_PP3300_INA_L);
 }
@@ -64,7 +65,7 @@ static void ina_connect(void)
 
 void usb_i2c_board_disable(void)
 {
-	if (!i2c_enabled())
+	if (!usb_i2c_board_is_enabled())
 		return;
 
 	ina_disconnect();
@@ -78,8 +79,41 @@ int usb_i2c_board_enable(void)
 		return EC_ERROR_BUSY;
 	}
 
-	if (!i2c_enabled())
+	if (ccd_get_mode() != CCD_MODE_ENABLED)
+		return EC_ERROR_BUSY;
+
+	if (!ccd_is_cap_enabled(CCD_CAP_I2C))
+		return EC_ERROR_ACCESS_DENIED;
+
+	if (!usb_i2c_board_is_enabled())
 		ina_connect();
 
 	return EC_SUCCESS;
 }
+
+/**
+ * CCD config change hook
+ */
+static void ccd_change_i2c(void)
+{
+	/*
+	 * If the capability state doesn't match the current I2C enable state,
+	 * try to make them match.
+	 */
+	if (usb_i2c_board_is_enabled() && !ccd_is_cap_enabled(CCD_CAP_I2C)) {
+		/* I2C bridge is enabled, but it's no longer allowed to be */
+		usb_i2c_board_disable();
+	} else if (!usb_i2c_board_is_enabled() &&
+		   ccd_is_cap_enabled(CCD_CAP_I2C)) {
+		/*
+		 * I2C bridge is disabled, but is allowed to be enabled.  Try
+		 * enabling it.  Note that this could fail for several reasons,
+		 * such as CCD not connected, or servo attached.  That's ok;
+		 * those things will also attempt usb_i2c_board_enable() if
+		 * their state changes later.
+		 */
+		usb_i2c_board_enable();
+	}
+}
+
+DECLARE_HOOK(HOOK_CCD_CHANGE, ccd_change_i2c, HOOK_PRIO_DEFAULT);