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gpio: Add a way to read 3-way strapping pins

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Using the internal vs. external pull resistors it is possible to get
27 different combinations from 3 strapping pins. Add an implementation
of this.

This involves updating the sandbox GPIO driver to model external and
(weaker) internal pull resistors. The get_value() method now takes account
of what is driving a pin:

   sandbox: GPIOD_EXT_DRIVEN - in which case GPIO_EXT_HIGH provides the
          value
   outside source - in which case GPIO_EXT_PULL_UP/DOWN indicates the
          external state and we work the final state using those flags and
          the internal GPIOD_PULL_UP/DOWN flags

Of course the outside source does not really exist in sandbox. We are just
modelling it for test purpose.

Signed-off-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Simon Glass
2021-02-04 21:22:09 -07:00
committed by Tom Rini
parent be04f1ab42
commit 8a45b22057
5 changed files with 232 additions and 5 deletions
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98
test/dm/gpio.c
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@@ -680,3 +680,101 @@ static int dm_test_clrset_flags_invert(struct unit_test_state *uts)
return 0;
}
DM_TEST(dm_test_clrset_flags_invert, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);
static int set_gpios(struct unit_test_state *uts, struct gpio_desc *desc,
int count, uint value)
{
int i;
for (i = 0; i < count; i++) {
const uint mask = 1 << i;
ut_assertok(sandbox_gpio_set_value(desc[i].dev, desc[i].offset,
value & mask));
}
return 0;
}
/* Check that an active-low GPIO works as expected */
static int dm_test_gpio_get_values_as_int(struct unit_test_state *uts)
{
const int gpio_count = 3;
struct gpio_desc desc[gpio_count];
struct udevice *dev;
ut_assertok(uclass_get_device(UCLASS_TEST_FDT, 0, &dev));
ut_asserteq_str("a-test", dev->name);
ut_asserteq(3, gpio_request_list_by_name(dev, "test-gpios", desc,
gpio_count, GPIOD_IS_IN));
ut_assertok(set_gpios(uts, desc, gpio_count, 0));
ut_asserteq(0, dm_gpio_get_values_as_int(desc, gpio_count));
ut_assertok(set_gpios(uts, desc, gpio_count, 5));
ut_asserteq(5, dm_gpio_get_values_as_int(desc, gpio_count));
ut_assertok(set_gpios(uts, desc, gpio_count, 7));
ut_asserteq(7, dm_gpio_get_values_as_int(desc, gpio_count));
return 0;
}
DM_TEST(dm_test_gpio_get_values_as_int,
UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);
/* Check that an active-low GPIO works as expected */
static int dm_test_gpio_get_values_as_int_base3(struct unit_test_state *uts)
{
const int gpio_count = 3;
struct gpio_desc desc[gpio_count];
struct udevice *dev;
ut_assertok(uclass_get_device(UCLASS_TEST_FDT, 0, &dev));
ut_asserteq_str("a-test", dev->name);
ut_asserteq(3, gpio_request_list_by_name(dev, "test-gpios", desc,
gpio_count, GPIOD_IS_IN));
/*
* First test the sandbox GPIO driver works as expected. The external
* pull resistor should be stronger than the internal one.
*/
sandbox_gpio_set_flags(desc[0].dev, desc[0].offset,
GPIOD_IS_IN | GPIOD_EXT_PULL_UP | GPIOD_PULL_UP);
ut_asserteq(1, dm_gpio_get_value(desc));
sandbox_gpio_set_flags(desc[0].dev, desc[0].offset, GPIOD_IS_IN |
GPIOD_EXT_PULL_DOWN | GPIOD_PULL_UP);
ut_asserteq(0, dm_gpio_get_value(desc));
sandbox_gpio_set_flags(desc[0].dev, desc[0].offset,
GPIOD_IS_IN | GPIOD_PULL_UP);
ut_asserteq(1, dm_gpio_get_value(desc));
sandbox_gpio_set_flags(desc[0].dev, desc[0].offset, GPIOD_PULL_DOWN);
ut_asserteq(0, dm_gpio_get_value(desc));
/*
* Set up pins: pull-up (1), pull-down (0) and floating (2). This should
* result in digits 2 0 1, i.e. 2 * 9 + 1 * 3 = 19
*/
sandbox_gpio_set_flags(desc[0].dev, desc[0].offset, GPIOD_EXT_PULL_UP);
sandbox_gpio_set_flags(desc[1].dev, desc[1].offset,
GPIOD_EXT_PULL_DOWN);
sandbox_gpio_set_flags(desc[2].dev, desc[2].offset, 0);
ut_asserteq(19, dm_gpio_get_values_as_int_base3(desc, gpio_count));
/*
* Set up pins: floating (2), pull-up (1) and pull-down (0). This should
* result in digits 0 1 2, i.e. 1 * 3 + 2 = 5
*/
sandbox_gpio_set_flags(desc[0].dev, desc[0].offset, 0);
sandbox_gpio_set_flags(desc[1].dev, desc[1].offset, GPIOD_EXT_PULL_UP);
sandbox_gpio_set_flags(desc[2].dev, desc[2].offset,
GPIOD_EXT_PULL_DOWN);
ut_asserteq(5, dm_gpio_get_values_as_int_base3(desc, gpio_count));
return 0;
}
DM_TEST(dm_test_gpio_get_values_as_int_base3,
UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);