usbc: fix vbus discharge path for GPIO

Code on Tot assumes that port count was the port to
discharge instead of port parameter

BRANCH=none
BUG=none
TEST=verified with unit test (in this CL)

Change-Id: I17658a0c555f9cea56fa4ec1652e0faf62e3d6cc
Signed-off-by: Jett Rink <jettrink@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1896125

board/host/gpio.inc

@@ -29,3 +29,5 @@ GPIO(BASE_CHG_VDD_EN,      PIN(0, 12), 0)
 
 /* Fingerprint */
 GPIO(SPI1_NSS,              PIN(0, 13), GPIO_OUT_HIGH)
+
+GPIO(USB_C0_DISCHARGE,     PIN(0, 15), 0)

common/usbc/usb_pe_drp_sm.c

@@ -4405,7 +4405,6 @@ int pd_charge_from_device(uint16_t vid, uint16_t pid)
 			(pid == USB_PID1_APPLE || pid == USB_PID2_APPLE));
 }
 
-#ifdef CONFIG_USB_PD_DISCHARGE
 void pd_set_vbus_discharge(int port, int enable)
 {
 	static struct mutex discharge_lock[CONFIG_USB_PD_PORT_MAX_COUNT];
@@ -4413,25 +4412,35 @@ void pd_set_vbus_discharge(int port, int enable)
 	mutex_lock(&discharge_lock[port]);
 	enable &= !board_vbus_source_enabled(port);
 
-#ifdef CONFIG_USB_PD_DISCHARGE_GPIO
+	if (IS_ENABLED(CONFIG_USB_PD_DISCHARGE_GPIO)) {
-#if CONFIG_USB_PD_PORT_MAX_COUNT == 0
+		switch (port) {
-	gpio_set_level(GPIO_USB_C0_DISCHARGE, enable);
+#if defined(CONFIG_USB_PD_DISCHARGE_GPIO) && CONFIG_USB_PD_PORT_MAX_COUNT >= 3
-#elif CONFIG_USB_PD_PORT_MAX_COUNT == 1
+		case 2:
-	gpio_set_level(GPIO_USB_C1_DISCHARGE, enable);
+			gpio_set_level(GPIO_USB_C2_DISCHARGE, enable);
-#elif CONFIG_USB_PD_PORT_MAX_COUNT == 2
+			break;
-	gpio_set_level(GPIO_USB_C2_DISCHARGE, enable);
-#elif CONFIG_USB_PD_PORT_MAX_COUNT == 3
-	gpio_set_level(GPIO_USB_C3_DISCHARGE, enable);
 #endif
-#else
+#if defined(CONFIG_USB_PD_DISCHARGE_GPIO) && CONFIG_USB_PD_PORT_MAX_COUNT >= 2
-	if (IS_ENABLED(CONFIG_USB_PD_DISCHARGE_TCPC))
+		case 1:
+			gpio_set_level(GPIO_USB_C1_DISCHARGE, enable);
+			break;
+#endif
+#if defined(CONFIG_USB_PD_DISCHARGE_GPIO) && CONFIG_USB_PD_PORT_MAX_COUNT >= 1
+		case 0:
+			gpio_set_level(GPIO_USB_C0_DISCHARGE, enable);
+			break;
+#endif
+		default:
+			CPRINTF("Could not discharge port %d via GPIO", port);
+			break;
+		}
+	} else if (IS_ENABLED(CONFIG_USB_PD_DISCHARGE_TCPC)) {
 		tcpc_discharge_vbus(port, enable);
-	else if (IS_ENABLED(CONFIG_USB_PD_DISCHARGE_PPC))
+	} else if (IS_ENABLED(CONFIG_USB_PD_DISCHARGE_PPC)) {
 		ppc_discharge_vbus(port, enable);
-#endif
+	}
+
 	mutex_unlock(&discharge_lock[port]);
 }
-#endif /* CONFIG_USB_PD_DISCHARGE */
 
 /* VDM utility functions */
 #ifdef CONFIG_USB_PD_ALT_MODE_DFP

fuzz/usb_pd_fuzz.c

@@ -186,6 +186,11 @@ void run_test(void)
 	}
 }
 
+int board_vbus_source_enabled(int port)
+{
+	return 0;
+}
+
 int test_fuzz_one_input(const uint8_t *data, unsigned int size)
 {
 	int i;

test/test_config.h

@@ -295,6 +295,7 @@ int ncp15wb_calculate_temp(uint16_t adc);
 #undef CONFIG_USB_TYPEC_SM
 #define CONFIG_USBC_VCONN
 #define PD_VCONN_SWAP_DELAY 5000 /* us */
+#define CONFIG_USB_PD_DISCHARGE_GPIO
 #endif
 
 /* Common TypeC tests defines */

test/usb_pe_drp.c

@@ -25,6 +25,11 @@ const struct svdm_response svdm_rsp = {
 	.modes = NULL,
 };
 
+int board_vbus_source_enabled(int port)
+{
+	return 0;
+}
+
 /**
  * Test section
  */
@@ -120,11 +125,23 @@ static int test_pe_frs(void)
 	return EC_SUCCESS;
 }
 
+static int test_vbus_gpio_discharge(void)
+{
+	pd_set_vbus_discharge(PORT0, 1);
+	TEST_EQ(gpio_get_level(GPIO_USB_C0_DISCHARGE), 1, "%d");
+
+	pd_set_vbus_discharge(PORT0, 0);
+	TEST_EQ(gpio_get_level(GPIO_USB_C0_DISCHARGE), 0, "%d");
+
+	return EC_SUCCESS;
+}
+
 void run_test(void)
 {
 	test_reset();
 
 	RUN_TEST(test_pe_frs);
+	RUN_TEST(test_vbus_gpio_discharge);
 
 	/* Do basic state machine sanity checks last. */
 	RUN_TEST(test_pe_no_parent_cycles);