@@ -94,18 +94,68 @@ static const VMStateDescription vmstate_pl061 = {
}
};
+static uint8_t pl061_floating(PL061State *s)
+{
+ /*
+ * Return mask of bits which correspond to pins configured as inputs
+ * and which are floating (neither pulled up to 1 nor down to 0).
+ */
+ uint8_t floating;
+
+ if (s->id == pl061_id_luminary) {
+ /*
+ * If both PUR and PDR bits are clear, there is neither a pullup
+ * nor a pulldown in place, and the output truly floats.
+ */
+ floating = ~(s->pur | s->pdr);
+ } else {
+ /* Assume outputs are pulled high. FIXME: this is board dependent. */
+ floating = 0;
+ }
+ return floating & ~s->dir;
+}
+
+static uint8_t pl061_pullups(PL061State *s)
+{
+ /*
+ * Return mask of bits which correspond to pins configured as inputs
+ * and which are pulled up to 1.
+ */
+ uint8_t pullups;
+
+ if (s->id == pl061_id_luminary) {
+ /*
+ * The Luminary variant of the PL061 has an extra registers which
+ * the guest can use to configure whether lines should be pullup
+ * or pulldown.
+ */
+ pullups = s->pur;
+ } else {
+ /* Assume outputs are pulled high. FIXME: this is board dependent. */
+ pullups = 0xff;
+ }
+ return pullups & ~s->dir;
+}
+
static void pl061_update(PL061State *s)
{
uint8_t changed;
uint8_t mask;
uint8_t out;
int i;
+ uint8_t pullups = pl061_pullups(s);
+ uint8_t floating = pl061_floating(s);
- trace_pl061_update(DEVICE(s)->canonical_path, s->dir, s->data);
+ trace_pl061_update(DEVICE(s)->canonical_path, s->dir, s->data,
+ pullups, floating);
- /* Outputs float high. */
- /* FIXME: This is board dependent. */
- out = (s->data & s->dir) | ~s->dir;
+ /*
+ * Pins configured as output are driven from the data register;
+ * otherwise if they're pulled up they're 1, and if they're floating
+ * then we give them the same value they had previously, so we don't
+ * report any change to the other end.
+ */
+ out = (s->data & s->dir) | pullups | (s->old_out_data & floating);
changed = s->old_out_data ^ out;
if (changed) {
s->old_out_data = out;
@@ -14,7 +14,7 @@ nrf51_gpio_set(int64_t line, int64_t value) "line %" PRIi64 " value %" PRIi64
nrf51_gpio_update_output_irq(int64_t line, int64_t value) "line %" PRIi64 " value %" PRIi64
# pl061.c
-pl061_update(const char *id, uint32_t dir, uint32_t data) "%s GPIODIR 0x%x GPIODATA 0x%x"
+pl061_update(const char *id, uint32_t dir, uint32_t data, uint32_t pullups, uint32_t floating) "%s GPIODIR 0x%x GPIODATA 0x%x pullups 0x%x floating 0x%x"
pl061_set_output(const char *id, int gpio, int level) "%s setting output %d to %d"
pl061_input_change(const char *id, int gpio, int level) "%s input %d changed to %d"
pl061_update_istate(const char *id, uint32_t istate, uint32_t im, int level) "%s GPIORIS 0x%x GPIOIE 0x%x interrupt level %d"
The Luminary variant of the PL061 has registers GPIOPUR and GPIOPDR which lets the guest configure whether the GPIO lines are pull-up, pull-down, or truly floating. Instead of assuming all lines are pulled high, honour the PUR and PDR registers. For the plain PL061, continue to assume that lines have an external pull-up resistor, as we did before. The stellaris board actually relies on this behaviour -- the CD line of the ssd0323 display device is connected to GPIO output C7, and it is only because of a different bug which we're about to fix that we weren't incorrectly driving this line high on reset and putting the ssd0323 into data mode. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> --- hw/gpio/pl061.c | 58 +++++++++++++++++++++++++++++++++++++++++--- hw/gpio/trace-events | 2 +- 2 files changed, 55 insertions(+), 5 deletions(-) -- 2.20.1