Check that a pin configured as output drives its OUTPUT register level onto the pin (push-pull) as reflected by the INPUT register, and that a pin configured as input floats high through its pull-up.
Signed-off-by: Emmanuel Blot <[email protected]> --- tests/qtest/pca9554-test.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) diff --git a/tests/qtest/pca9554-test.c b/tests/qtest/pca9554-test.c index a5f213a59c..ce6e90f3f8 100644 --- a/tests/qtest/pca9554-test.c +++ b/tests/qtest/pca9554-test.c @@ -25,6 +25,48 @@ static void test_reset_defaults(void *obj, void *data, QGuestAllocator *alloc) g_assert_cmphex(i2c_get8(dev, PCA9554_CONFIG), ==, 0xFF); } +/* + * A pin configured as output (config=0) drives its OUTPUT register level onto + * the pin (push-pull), which the INPUT register reflects. A pin configured as + * input (config=1) floats high through its pull-up. + */ +static void test_output_drives_input(void *obj, void *data, + QGuestAllocator *alloc) +{ + QI2CDevice *dev = (QI2CDevice *)obj; + + /* Low nibble output, high nibble input (pull-up). */ + i2c_set8(dev, PCA9554_CONFIG, 0xF0); + i2c_set8(dev, PCA9554_OUTPUT, 0xFA); + g_assert_cmphex(i2c_get8(dev, PCA9554_INPUT), ==, 0xFA); + + /* All outputs, driven low then high. */ + i2c_set8(dev, PCA9554_CONFIG, 0x00); + i2c_set8(dev, PCA9554_OUTPUT, 0x00); + g_assert_cmphex(i2c_get8(dev, PCA9554_INPUT), ==, 0x00); + + i2c_set8(dev, PCA9554_OUTPUT, 0xFF); + g_assert_cmphex(i2c_get8(dev, PCA9554_INPUT), ==, 0xFF); +} + +/* + * With all pins configured as inputs the pull-ups make the INPUT register read + * all ones regardless of the OUTPUT register; switching a pin to output with + * output=0 drives it low. + */ +static void test_input_pullup(void *obj, void *data, QGuestAllocator *alloc) +{ + QI2CDevice *dev = (QI2CDevice *)obj; + + g_assert_cmphex(i2c_get8(dev, PCA9554_INPUT), ==, 0xFF); + + i2c_set8(dev, PCA9554_OUTPUT, 0x00); + g_assert_cmphex(i2c_get8(dev, PCA9554_INPUT), ==, 0xFF); + + i2c_set8(dev, PCA9554_CONFIG, 0x00); + g_assert_cmphex(i2c_get8(dev, PCA9554_INPUT), ==, 0x00); +} + static void pca9554_register_nodes(void) { QOSGraphEdgeOptions opts = { @@ -36,6 +78,9 @@ static void pca9554_register_nodes(void) qos_node_consumes("pca9554", "i2c-bus", &opts); qos_add_test("reset-defaults", "pca9554", test_reset_defaults, NULL); + qos_add_test("output-drives-input", "pca9554", test_output_drives_input, + NULL); + qos_add_test("input-pullup", "pca9554", test_input_pullup, NULL); } libqos_init(pca9554_register_nodes); -- 2.50.1
