diff options
Diffstat (limited to 'hw/gpio/nrf51_gpio.c')
| -rw-r--r-- | hw/gpio/nrf51_gpio.c | 65 |
1 files changed, 40 insertions, 25 deletions
diff --git a/hw/gpio/nrf51_gpio.c b/hw/gpio/nrf51_gpio.c index 86e047d649..87a2f2a0dc 100644 --- a/hw/gpio/nrf51_gpio.c +++ b/hw/gpio/nrf51_gpio.c @@ -43,6 +43,17 @@ static bool is_connected(uint32_t config, uint32_t level) return state; } +static int pull_value(uint32_t config) +{ + int pull = extract32(config, 2, 2); + if (pull == NRF51_GPIO_PULLDOWN) { + return 0; + } else if (pull == NRF51_GPIO_PULLUP) { + return 1; + } + return -1; +} + static void update_output_irq(NRF51GPIOState *s, size_t i, bool connected, bool level) { @@ -61,43 +72,47 @@ static void update_output_irq(NRF51GPIOState *s, size_t i, static void update_state(NRF51GPIOState *s) { - uint32_t pull; + int pull; size_t i; - bool connected_out, dir, connected_in, out, input; + bool connected_out, dir, connected_in, out, in, input; for (i = 0; i < NRF51_GPIO_PINS; i++) { - pull = extract32(s->cnf[i], 2, 2); + pull = pull_value(s->cnf[i]); dir = extract32(s->cnf[i], 0, 1); connected_in = extract32(s->in_mask, i, 1); out = extract32(s->out, i, 1); + in = extract32(s->in, i, 1); input = !extract32(s->cnf[i], 1, 1); connected_out = is_connected(s->cnf[i], out) && dir; - update_output_irq(s, i, connected_out, out); - - /* Pin both driven externally and internally */ - if (connected_out && connected_in) { - qemu_log_mask(LOG_GUEST_ERROR, "GPIO pin %zu short circuited\n", i); - } - - /* - * Input buffer disconnected from internal/external drives, so - * pull-up/pull-down becomes relevant - */ - if (!input || (input && !connected_in && !connected_out)) { - if (pull == NRF51_GPIO_PULLDOWN) { - s->in = deposit32(s->in, i, 1, 0); - } else if (pull == NRF51_GPIO_PULLUP) { - s->in = deposit32(s->in, i, 1, 1); + if (!input) { + if (pull >= 0) { + /* Input buffer disconnected from external drives */ + s->in = deposit32(s->in, i, 1, pull); + } + } else { + if (connected_out && connected_in && out != in) { + /* Pin both driven externally and internally */ + qemu_log_mask(LOG_GUEST_ERROR, + "GPIO pin %zu short circuited\n", i); + } + if (!connected_in) { + /* + * Floating input: the output stimulates IN if connected, + * otherwise pull-up/pull-down resistors put a value on both + * IN and OUT. + */ + if (pull >= 0 && !connected_out) { + connected_out = true; + out = pull; + } + if (connected_out) { + s->in = deposit32(s->in, i, 1, out); + } } } - - /* Self stimulation through internal output driver */ - if (connected_out && !connected_in && input) { - s->in = deposit32(s->in, i, 1, out); - } + update_output_irq(s, i, connected_out, out); } - } /* |