diff --git a/thermosphere/src/platform/tegra/uart.c b/thermosphere/src/platform/tegra/uart.c index f48bd17d5..bab82a5fb 100644 --- a/thermosphere/src/platform/tegra/uart.c +++ b/thermosphere/src/platform/tegra/uart.c @@ -21,9 +21,19 @@ #include "gpio.h" #include "car.h" +static inline void uart_wait_cycles(uint32_t baud, uint32_t num) +{ + udelay((num * 1000000 + 16 * baud - 1) / (16 * baud)); +} + +static inline void uart_wait_syms(uint32_t baud, uint32_t num) +{ + udelay((num * 1000000 + baud - 1) / baud); +} + void uart_config(UartDevice dev) { volatile tegra_pinmux_t *pinmux = pinmux_get_regs(); - + switch (dev) { case UART_A: pinmux->uart1_tx = 0; @@ -75,7 +85,7 @@ void uart_init(UartDevice dev, uint32_t baud, bool inverted) { /* Wait for idle state. */ uart_wait_idle(dev, UART_VENDOR_STATE_TX_IDLE); - /* Calculate baud rate. */ + /* Calculate baud rate, round to nearest. */ uint32_t rate = (8 * baud + 408000000) / (16 * baud); /* Setup UART in FIFO mode. */ @@ -85,14 +95,20 @@ void uart_init(UartDevice dev, uint32_t baud, bool inverted) { uart->UART_THR_DLAB = (uint8_t)rate; /* Divisor latch LSB. */ uart->UART_IER_DLAB = (uint8_t)(rate >> 8); /* Divisor latch MSB. */ uart->UART_LCR &= ~(UART_LCR_DLAB); /* Disable DLAB. */ - + uart->UART_SPR; /* Dummy read. */ + uart_wait_syms(baud, 3); /* Wait for 3 symbols at the new baudrate. */ + + /* Enable FIFO with default settings. */ + uart->UART_IIR_FCR = UART_FCR_FCR_EN_FIFO; + uart->UART_IRDA_CSR = inverted ? 2 : 0; /* Invert TX if needed */ + uart->UART_SPR; /* Dummy read as mandated by TRM. */ + uart_wait_cycles(baud, 3); /* Wait for 3 baud cycles, as mandated by TRM (erratum). */ + /* Flush FIFO. */ - uart->UART_IIR_FCR = (UART_FCR_FCR_EN_FIFO | UART_FCR_RX_CLR | UART_FCR_TX_CLR); /* Enable and clear TX and RX FIFOs. */ - uart->UART_IRDA_CSR = inverted ? 2 : 0; /* Invert TX */ - uart->UART_SPR; - udelay(3 * ((baud + 999999) / baud)); - - /* Wait for idle state. */ + uart_wait_idle(dev, UART_VENDOR_STATE_TX_IDLE); /* Make sure there's no data being written in TX FIFO (TRM). */ + uart->UART_IIR_FCR |= UART_FCR_RX_CLR | UART_FCR_TX_CLR; /* Clear TX and RX FIFOs. */ + uart_wait_cycles(baud, 32); /* Wait for 32 baud cycles (TRM, erratum). */ + /* Wait for idle state (TRM). */ uart_wait_idle(dev, UART_VENDOR_STATE_TX_IDLE | UART_VENDOR_STATE_RX_IDLE); }