Reviewed-by: Glenn Miles <[email protected]> Thanks,
Glenn On Thu, 2026-07-09 at 17:23 +0200, Emmanuel Blot wrote: > Verify that the polarity register inverts the value read back from the > INPUT register, both on pulled-up inputs and on output-driven pins, while > leaving the OUTPUT register itself unchanged. > > Signed-off-by: Emmanuel Blot <[email protected]> > --- > tests/qtest/pca9554-test.c | 39 +++++++++++++++++++++++++++++++++++++++ > 1 file changed, 39 insertions(+) > > diff --git a/tests/qtest/pca9554-test.c b/tests/qtest/pca9554-test.c > index ce6e90f3f8..74237df611 100644 > --- a/tests/qtest/pca9554-test.c > +++ b/tests/qtest/pca9554-test.c > @@ -67,6 +67,41 @@ static void test_input_pullup(void *obj, void *data, > QGuestAllocator *alloc) > g_assert_cmphex(i2c_get8(dev, PCA9554_INPUT), ==, 0x00); > } > > +/* > + * Polarity inversion: reading INPUT returns the XOR of the pin levels and > the > + * polarity register. > + */ > +static void test_polarity_inversion(void *obj, void *data, > + QGuestAllocator *alloc) > +{ > + QI2CDevice *dev = (QI2CDevice *)obj; > + > + g_assert_cmphex(i2c_get8(dev, PCA9554_INPUT), ==, 0xFF); > + > + i2c_set8(dev, PCA9554_POLARITY, 0xFF); > + g_assert_cmphex(i2c_get8(dev, PCA9554_INPUT), ==, 0x00); > + > + i2c_set8(dev, PCA9554_POLARITY, 0x0F); > + g_assert_cmphex(i2c_get8(dev, PCA9554_INPUT), ==, 0xF0); > +} > + > +/* Polarity inversion combined with output-driven pins. */ > +static void test_polarity_with_output(void *obj, void *data, > + QGuestAllocator *alloc) > +{ > + QI2CDevice *dev = (QI2CDevice *)obj; > + > + i2c_set8(dev, PCA9554_CONFIG, 0x00); > + i2c_set8(dev, PCA9554_OUTPUT, 0xA5); > + g_assert_cmphex(i2c_get8(dev, PCA9554_INPUT), ==, 0xA5); > + > + i2c_set8(dev, PCA9554_POLARITY, 0xFF); > + g_assert_cmphex(i2c_get8(dev, PCA9554_INPUT), ==, 0x5A); > + > + /* Inversion only affects the INPUT read, not the OUTPUT register. */ > + g_assert_cmphex(i2c_get8(dev, PCA9554_OUTPUT), ==, 0xA5); > +} > + > static void pca9554_register_nodes(void) > { > QOSGraphEdgeOptions opts = { > @@ -81,6 +116,10 @@ static void pca9554_register_nodes(void) > qos_add_test("output-drives-input", "pca9554", test_output_drives_input, > NULL); > qos_add_test("input-pullup", "pca9554", test_input_pullup, NULL); > + qos_add_test("polarity-inversion", "pca9554", test_polarity_inversion, > + NULL); > + qos_add_test("polarity-with-output", "pca9554", > test_polarity_with_output, > + NULL); > } > > libqos_init(pca9554_register_nodes); >
