diff options
Diffstat (limited to 'sys/mips/atheros/uart_dev_ar933x.c')
| -rw-r--r-- | sys/mips/atheros/uart_dev_ar933x.c | 165 |
1 files changed, 95 insertions, 70 deletions
diff --git a/sys/mips/atheros/uart_dev_ar933x.c b/sys/mips/atheros/uart_dev_ar933x.c index ad1736b..a6fbc83 100644 --- a/sys/mips/atheros/uart_dev_ar933x.c +++ b/sys/mips/atheros/uart_dev_ar933x.c @@ -147,45 +147,94 @@ ar933x_flush(struct uart_bas *bas, int what) } #endif -#if 0 +/* + * Calculate the baud from the given chip configuration parameters. + */ +static unsigned long +ar933x_uart_get_baud(unsigned int clk, unsigned int scale, + unsigned int step) +{ + uint64_t t; + uint32_t div; + + div = (2 << 16) * (scale + 1); + t = clk; + t *= step; + t += (div / 2); + t = t / div; + + return (t); +} + +/* + * Calculate the scale/step with the lowest possible deviation from + * the target baudrate. + */ +static void +ar933x_uart_get_scale_step(struct uart_bas *bas, unsigned int baud, + unsigned int *scale, unsigned int *step) +{ + unsigned int tscale; + uint32_t clk; + long min_diff; + + clk = bas->rclk; + *scale = 0; + *step = 0; + + min_diff = baud; + for (tscale = 0; tscale < AR933X_UART_MAX_SCALE; tscale++) { + uint64_t tstep; + int diff; + + tstep = baud * (tscale + 1); + tstep *= (2 << 16); + tstep = tstep / clk; + + if (tstep > AR933X_UART_MAX_STEP) + break; + + diff = abs(ar933x_uart_get_baud(clk, tscale, tstep) - baud); + if (diff < min_diff) { + min_diff = diff; + *scale = tscale; + *step = tstep; + } + } +} + static int ar933x_param(struct uart_bas *bas, int baudrate, int databits, int stopbits, int parity) { - int divisor; - uint8_t lcr; - - lcr = 0; - if (databits >= 8) - lcr |= LCR_8BITS; - else if (databits == 7) - lcr |= LCR_7BITS; - else if (databits == 6) - lcr |= LCR_6BITS; - else - lcr |= LCR_5BITS; - if (stopbits > 1) - lcr |= LCR_STOPB; - lcr |= parity << 3; - - /* Set baudrate. */ + /* UART always 8 bits */ + + /* UART always 1 stop bit */ + + /* UART parity is controllable by bits 0:1, ignore for now */ + + /* Set baudrate if required. */ if (baudrate > 0) { - divisor = ar933x_divisor(bas->rclk, baudrate); - if (divisor == 0) - return (EINVAL); - uart_setreg(bas, REG_LCR, lcr | LCR_DLAB); - uart_barrier(bas); - uart_setreg(bas, REG_DLL, divisor & 0xff); - uart_setreg(bas, REG_DLH, (divisor >> 8) & 0xff); - uart_barrier(bas); + uint32_t clock_scale, clock_step; + + /* Find the best fit for the given baud rate */ + ar933x_uart_get_scale_step(bas, baudrate, &clock_scale, + &clock_step); + + /* + * Program the clock register in its entirety - no need + * for Read-Modify-Write. + */ + ar933x_setreg(bas, AR933X_UART_CLOCK_REG, + ((clock_scale & AR933X_UART_CLOCK_SCALE_M) + << AR933X_UART_CLOCK_SCALE_S) | + (clock_step & AR933X_UART_CLOCK_STEP_M)); } - /* Set LCR and clear DLAB. */ - uart_setreg(bas, REG_LCR, lcr); uart_barrier(bas); return (0); } -#endif + /* * Low-level UART interface. @@ -209,23 +258,8 @@ static struct uart_ops uart_ar933x_ops = { static int ar933x_probe(struct uart_bas *bas) { -#if 0 - u_char val; - /* Check known 0 bits that don't depend on DLAB. */ - val = uart_getreg(bas, REG_IIR); - if (val & 0x30) - return (ENXIO); - /* - * Bit 6 of the MCR (= 0x40) appears to be 1 for the Sun1699 - * chip, but otherwise doesn't seem to have a function. In - * other words, uart(4) works regardless. Ignore that bit so - * the probe succeeds. - */ - val = uart_getreg(bas, REG_MCR); - if (val & 0xa0) - return (ENXIO); -#endif + /* We always know this will be here */ return (0); } @@ -233,43 +267,34 @@ static void ar933x_init(struct uart_bas *bas, int baudrate, int databits, int stopbits, int parity) { -#if 0 - u_char ier; + uint32_t reg; - if (bas->rclk == 0) - bas->rclk = DEFAULT_RCLK; + /* Setup default parameters */ ar933x_param(bas, baudrate, databits, stopbits, parity); - /* Disable all interrupt sources. */ - /* - * We use 0xe0 instead of 0xf0 as the mask because the XScale PXA - * UARTs split the receive time-out interrupt bit out separately as - * 0x10. This gets handled by ier_mask and ier_rxbits below. - */ - ier = uart_getreg(bas, REG_IER) & 0xe0; - uart_setreg(bas, REG_IER, ier); - uart_barrier(bas); + /* XXX Force enable UART in case it was disabled */ - /* Disable the FIFO (if present). */ - uart_setreg(bas, REG_FCR, 0); - uart_barrier(bas); + /* Disable all interrupts */ + ar933x_setreg(bas, AR933X_UART_INT_EN_REG, 0x00000000); + + /* Disable the host interrupt */ + reg = ar933x_getreg(bas, AR933X_UART_CS_REG); + reg &= ~AR933X_UART_CS_HOST_INT_EN; + ar933x_setreg(bas, AR933X_UART_CS_REG, reg); - /* Set RTS & DTR. */ - uart_setreg(bas, REG_MCR, MCR_IE | MCR_RTS | MCR_DTR); uart_barrier(bas); - ar933x_clrint(bas); -#endif + /* XXX Set RTS/DTR? */ } +/* + * Detach from console. + */ static void ar933x_term(struct uart_bas *bas) { -#if 0 - /* Clear RTS & DTR. */ - uart_setreg(bas, REG_MCR, MCR_IE); - uart_barrier(bas); -#endif + + /* XXX TODO */ } static void |
