zephyr test: Set ISL923x in natural units

Accept voltage in mV as an argument to isl923x_emul_set_adc_vbus. Test
using this interface.

BUG=b:216497851
TEST=zmake testall
BRANCH=none

Signed-off-by: Abe Levkoy <alevkoy@chromium.org>
Change-Id: I8a0ec6019f1d4ef7853d731b11726e4fb1bdf136
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3425638
Reviewed-by: Yuval Peress <peress@google.com>

4 files changed, 19 insertions, 21 deletions

diff --git a/zephyr/emul/emul_isl923x.c b/zephyr/emul/emul_isl923x.c
index 56287d531e..399bf167a5 100644
--- a/zephyr/emul/emul_isl923x.c
+++ b/zephyr/emul/emul_isl923x.c
@@ -174,13 +174,12 @@ void isl923x_emul_set_learn_mode_enabled(const struct emul *emulator,
 		data->control_1_reg &= ~ISL923X_C1_LEARN_MODE_ENABLE;
 }
 
-void isl923x_emul_set_adc_vbus(const struct emul *emulator,
-			       uint16_t value)
+void isl923x_emul_set_adc_vbus(const struct emul *emulator, uint16_t vbus_mv)
 {
 	struct isl923x_emul_data *data = emulator->data;
 
 	/* The VBUS voltage is returned in bits 13:6. The LSB is 96mV. */
-	data->adc_vbus_reg = value & GENMASK(13, 6);
+	data->adc_vbus_reg = ((vbus_mv / 96) << 6) & GENMASK(13, 6);
 }
 
 void raa489000_emul_set_acok_pin(const struct emul *emulator, uint16_t value)
diff --git a/zephyr/include/emul/emul_isl923x.h b/zephyr/include/emul/emul_isl923x.h
index 659b620f21..93a29a9c09 100644
--- a/zephyr/include/emul/emul_isl923x.h
+++ b/zephyr/include/emul/emul_isl923x.h
@@ -74,10 +74,9 @@ void isl923x_emul_set_learn_mode_enabled(const struct emul *emulator,
  * @brief Set the emulator's ADC vbus register
  *
  * @param emulator The emulator to modify
- * @param value The new ADC register value
+ * @param vbus_mv  VBUS voltage in mV
  */
-void isl923x_emul_set_adc_vbus(const struct emul *emulator,
-			       uint16_t value);
+void isl923x_emul_set_adc_vbus(const struct emul *emulator, uint16_t vbus_mv);
 
 /**
  * @brief Set the state of the ACOK pin, which is reflected in the INFO2
diff --git a/zephyr/test/drivers/src/integration_usb.c b/zephyr/test/drivers/src/integration_usb.c
index b9f3bc1cf6..320d3ebb7b 100644
--- a/zephyr/test/drivers/src/integration_usb.c
+++ b/zephyr/test/drivers/src/integration_usb.c
@@ -203,8 +203,7 @@ ZTEST(integration_usb, test_attach_5v_pd_charger)
 						   &my_charger.common_data,
 						   &my_charger.ops, tcpci_emul),
 		   NULL);
-	/* This corresponds to 4.992V. */
-	isl923x_emul_set_adc_vbus(charger_emul, 0x0d00);
+	isl923x_emul_set_adc_vbus(charger_emul, 5000);
 
 	/* Wait for current ramp. */
 	k_sleep(K_SECONDS(10));
@@ -249,12 +248,7 @@ ZTEST(integration_usb, test_attach_20v_pd_charger)
 						   &my_charger.common_data,
 						   &my_charger.ops, tcpci_emul),
 		   NULL);
-	/* This corresponds to 20.352V according to the scheme used by
-	 * isl923x_get_vbus_voltage, which is slightly different than that
-	 * described in the ISL9238 datasheet.
-	 * TODO(b/216497851): Specify this in natural units.
-	 */
-	isl923x_emul_set_adc_vbus(charger_emul, 0x3500);
+	isl923x_emul_set_adc_vbus(charger_emul, 20000);
 
 	/* Wait for PD negotiation and current ramp.
 	 * TODO(b/213906889): Check message timing and contents.
diff --git a/zephyr/test/drivers/src/isl923x.c b/zephyr/test/drivers/src/isl923x.c
index a5abee0fc5..c2e0f00c76 100644
--- a/zephyr/test/drivers/src/isl923x.c
+++ b/zephyr/test/drivers/src/isl923x.c
@@ -545,8 +545,8 @@ ZTEST(isl923x, test_get_vbus_voltage)
 {
 	const struct emul *isl923x_emul = ISL923X_EMUL;
 	struct i2c_emul *i2c_emul = isl923x_emul_get_i2c_emul(isl923x_emul);
-	int reg_values[] = { BIT(6),  BIT(7),  BIT(8),	BIT(9),
-			     BIT(10), BIT(11), BIT(12), BIT(13) };
+	/* Standard fixed-power PD source voltages. */
+	int test_voltage_mv[] = { 5000, 9000, 15000, 20000 };
 	int voltage;
 
 	/* Test fail to read the ADC vbus register */
@@ -557,15 +557,21 @@ ZTEST(isl923x, test_get_vbus_voltage)
 	i2c_common_emul_set_read_fail_reg(i2c_emul,
 					  I2C_COMMON_EMUL_NO_FAIL_REG);
 
-	for (int i = 0; i < ARRAY_SIZE(reg_values); ++i) {
-		int expected_voltage = (reg_values[i] >> 6) * 96;
+	for (int i = 0; i < ARRAY_SIZE(test_voltage_mv); ++i) {
+		int expected_voltage_mv = test_voltage_mv[i];
 
-		isl923x_emul_set_adc_vbus(isl923x_emul, reg_values[i]);
+		isl923x_emul_set_adc_vbus(isl923x_emul, expected_voltage_mv);
 		zassert_ok(isl923x_drv.get_vbus_voltage(CHARGER_NUM, 0,
 							&voltage),
 			   NULL);
-		zassert_equal(expected_voltage, voltage,
-			      "Expected %dmV but got %dmV", expected_voltage,
+		/* isl923x_get_vbus_voltage treats the measured voltage as
+		 * having an effective step size of 96 mV. This is slightly
+		 * different than the scheme described in the ISL9238 datasheet.
+		 * Reported VBUS should therefore be within 100 mV of nominal
+		 * VBUS.
+		 */
+		zassert_within(expected_voltage_mv, voltage, 100,
+			      "Expected %dmV but got %dmV", expected_voltage_mv,
 			      voltage);
 	}
 }