diff options
Diffstat (limited to 'c/src/lib/libbsp/arm/xilinx-zynq/console/zynq-uart.c')
| -rw-r--r-- | c/src/lib/libbsp/arm/xilinx-zynq/console/zynq-uart.c | 112 |
1 files changed, 110 insertions, 2 deletions
diff --git a/c/src/lib/libbsp/arm/xilinx-zynq/console/zynq-uart.c b/c/src/lib/libbsp/arm/xilinx-zynq/console/zynq-uart.c index 1ac7352161..cf47f04ed2 100644 --- a/c/src/lib/libbsp/arm/xilinx-zynq/console/zynq-uart.c +++ b/c/src/lib/libbsp/arm/xilinx-zynq/console/zynq-uart.c @@ -25,10 +25,100 @@ static volatile zynq_uart *zynq_uart_get_regs(int minor) return (volatile zynq_uart *) ct->ulCtrlPort1; } +/* + * Make weak and let the user override. + */ +uint32_t zynq_uart_input_clock(void) __attribute__ ((weak)); + +uint32_t zynq_uart_input_clock(void) +{ + return 100000000UL; +} + +static int zynq_cal_baud_rate(uint32_t baudrate, + uint32_t* brgr, + uint32_t* bauddiv, + uint32_t modereg) +{ + uint32_t brgr_value; /* Calculated value for baud rate generator */ + uint32_t calcbaudrate; /* Calculated baud rate */ + uint32_t bauderror; /* Diff between calculated and requested baud rate */ + uint32_t best_error = 0xFFFFFFFF; + uint32_t percenterror; + uint32_t bdiv; + uint32_t inputclk = zynq_uart_input_clock(); + + /* + * Make sure the baud rate is not impossilby large. + * Fastest possible baud rate is Input Clock / 2. + */ + if ((baudrate * 2) > inputclk) { + return -1; + } + /* + * Check whether the input clock is divided by 8 + */ + if(modereg & ZYNQ_UART_MODE_CLKS) { + inputclk = inputclk / 8; + } + + /* + * Determine the Baud divider. It can be 4to 254. + * Loop through all possible combinations + */ + for (bdiv = 4; bdiv < 255; bdiv++) { + + /* + * Calculate the value for BRGR register + */ + brgr_value = inputclk / (baudrate * (bdiv + 1)); + + /* + * Calculate the baud rate from the BRGR value + */ + calcbaudrate = inputclk/ (brgr_value * (bdiv + 1)); + + /* + * Avoid unsigned integer underflow + */ + if (baudrate > calcbaudrate) { + bauderror = baudrate - calcbaudrate; + } + else { + bauderror = calcbaudrate - baudrate; + } + + /* + * Find the calculated baud rate closest to requested baud rate. + */ + if (best_error > bauderror) { + *brgr = brgr_value; + *bauddiv = bdiv; + best_error = bauderror; + } + } + + /* + * Make sure the best error is not too large. + */ + percenterror = (best_error * 100) / baudrate; +#define XUARTPS_MAX_BAUD_ERROR_RATE 3 /* max % error allowed */ + if (XUARTPS_MAX_BAUD_ERROR_RATE < percenterror) { + return -1; + } + + return 0; +} + static void zynq_uart_initialize(int minor) { volatile zynq_uart *regs = zynq_uart_get_regs(minor); + uint32_t brgr = 0x3e; + uint32_t bauddiv = 0x6; + zynq_cal_baud_rate(115200, &brgr, &bauddiv, regs->mode); + + regs->control &= ~(ZYNQ_UART_CONTROL_RXEN | ZYNQ_UART_CONTROL_TXEN); regs->control = ZYNQ_UART_CONTROL_RXDIS | ZYNQ_UART_CONTROL_TXDIS | ZYNQ_UART_CONTROL_RXRES @@ -36,8 +126,8 @@ static void zynq_uart_initialize(int minor) regs->mode = ZYNQ_UART_MODE_CHMODE(ZYNQ_UART_MODE_CHMODE_NORMAL) | ZYNQ_UART_MODE_PAR(ZYNQ_UART_MODE_PAR_NONE) | ZYNQ_UART_MODE_CHRL(ZYNQ_UART_MODE_CHRL_8); - regs->baud_rate_gen = ZYNQ_UART_BAUD_RATE_GEN_CD(0x3e); - regs->baud_rate_div = ZYNQ_UART_BAUD_RATE_DIV_BDIV(0x6); + regs->baud_rate_gen = ZYNQ_UART_BAUD_RATE_GEN_CD(brgr); + regs->baud_rate_div = ZYNQ_UART_BAUD_RATE_DIV_BDIV(bauddiv); regs->rx_fifo_trg_lvl = ZYNQ_UART_RX_FIFO_TRG_LVL_RTRIG(0); regs->rx_timeout = ZYNQ_UART_RX_TIMEOUT_RTO(0); regs->control = ZYNQ_UART_CONTROL_RXEN @@ -102,7 +192,25 @@ static ssize_t zynq_uart_write_support_polled( static int zynq_uart_set_attribues(int minor, const struct termios *term) { +#if 0 + volatile zynq_uart *regs = zynq_uart_get_regs(minor); + uint32_t brgr = 0; + uint32_t bauddiv = 0; + int rc; + + rc = zynq_cal_baud_rate(115200, &brgr, &bauddiv, regs->mode); + if (rc != 0) + return rc; + + regs->control &= ~(ZYNQ_UART_CONTROL_RXEN | ZYNQ_UART_CONTROL_TXEN); + regs->baud_rate_gen = ZYNQ_UART_BAUD_RATE_GEN_CD(brgr); + regs->baud_rate_div = ZYNQ_UART_BAUD_RATE_DIV_BDIV(bauddiv); + regs->control |= ZYNQ_UART_CONTROL_RXEN | ZYNQ_UART_CONTROL_TXEN; + + return 0; +#else return -1; +#endif } const console_fns zynq_uart_fns = { |