diff options
Diffstat (limited to 'drivers/ti/uart/16550_console.S')
| -rw-r--r-- | drivers/ti/uart/16550_console.S | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/drivers/ti/uart/16550_console.S b/drivers/ti/uart/16550_console.S new file mode 100644 index 0000000..ebb4615 --- /dev/null +++ b/drivers/ti/uart/16550_console.S @@ -0,0 +1,155 @@ +/* + * Copyright (c) 2015, ARM Limited and Contributors. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * Redistributions of source code must retain the above copyright notice, this + * list of conditions and the following disclaimer. + * + * Redistributions in binary form must reproduce the above copyright notice, + * this list of conditions and the following disclaimer in the documentation + * and/or other materials provided with the distribution. + * + * Neither the name of ARM nor the names of its contributors may be used + * to endorse or promote products derived from this software without specific + * prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + +#include <arch.h> +#include <asm_macros.S> +#include <uart_16550.h> + + .globl console_core_init + .globl console_core_putc + .globl console_core_getc + + /* ----------------------------------------------- + * int console_core_init(unsigned long base_addr, + * unsigned int uart_clk, unsigned int baud_rate) + * Function to initialize the console without a + * C Runtime to print debug information. This + * function will be accessed by console_init and + * crash reporting. + * In: x0 - console base address + * w1 - Uart clock in Hz + * w2 - Baud rate + * Out: return 1 on success + * Clobber list : x1, x2, x3 + * ----------------------------------------------- + */ +func console_core_init + /* Check the input base address */ + cbz x0, init_fail + /* Check baud rate and uart clock for sanity */ + cbz w1, init_fail + cbz w2, init_fail + + /* Program the baudrate */ + /* Divisor = Uart clock / (16 * baudrate) */ + lsl w2, w2, #4 + udiv w2, w1, w2 + and w1, w2, #0xff /* w1 = DLL */ + lsr w2, w2, #8 + and w2, w2, #0xff /* w2 = DLLM */ + ldr w3, [x0, #UARTLCR] + orr w3, w3, #UARTLCR_DLAB + str w3, [x0, #UARTLCR] /* enable DLL, DLLM programming */ + str w1, [x0, #UARTDLL] /* program DLL */ + str w2, [x0, #UARTDLLM] /* program DLLM */ + mov w2, #~UARTLCR_DLAB + and w3, w3, w2 + str w3, [x0, #UARTLCR] /* disable DLL, DLLM programming */ + + /* 8n1 */ + mov w3, #3 + str w3, [x0, #UARTLCR] + /* no interrupt */ + mov w3, #0 + str w3, [x0, #UARTIER] + /* enable fifo, DMA */ + mov w3, #(UARTFCR_FIFOEN | UARTFCR_DMAEN) + str w3, [x0, #UARTFCR] + /* DTR + RTS */ + mov w3, #3 + str w3, [x0, #UARTMCR] + mov w0, #1 +init_fail: + ret +endfunc console_core_init + + /* -------------------------------------------------------- + * int console_core_putc(int c, unsigned int base_addr) + * Function to output a character over the console. It + * returns the character printed on success or -1 on error. + * In : w0 - character to be printed + * x1 - console base address + * Out : return -1 on error else return character. + * Clobber list : x2 + * -------------------------------------------------------- + */ +func console_core_putc + /* Check the input parameter */ + cbz x1, putc_error + + /* Prepend '\r' to '\n' */ + cmp w0, #0xA + b.ne 2f + /* Check if the transmit FIFO is full */ +1: ldr w2, [x1, #UARTLSR] + and w2, w2, #(UARTLSR_TEMT | UARTLSR_THRE) + cmp w2, #(UARTLSR_TEMT | UARTLSR_THRE) + b.ne 1b + mov w2, #0xD /* '\r' */ + str w2, [x1, #UARTTX] + ldr w2, [x1, #UARTFCR] + orr w2, w2, #UARTFCR_TXCLR + str w2, [x1, #UARTFCR] + + /* Check if the transmit FIFO is full */ +2: ldr w2, [x1, #UARTLSR] + and w2, w2, #(UARTLSR_TEMT | UARTLSR_THRE) + cmp w2, #(UARTLSR_TEMT | UARTLSR_THRE) + b.ne 2b + str w0, [x1, #UARTTX] + ldr w2, [x1, #UARTFCR] + orr w2, w2, #UARTFCR_TXCLR + str w2, [x1, #UARTFCR] + ret +putc_error: + mov w0, #-1 + ret +endfunc console_core_putc + + /* --------------------------------------------- + * int console_core_getc(void) + * Function to get a character from the console. + * It returns the character grabbed on success + * or -1 on error. + * In : w0 - console base address + * Out : return -1 on error else return character. + * Clobber list : x0, x1 + * --------------------------------------------- + */ +func console_core_getc + /* Check if the receive FIFO is empty */ +1: ldr w1, [x0, #UARTLSR] + tbz w1, #UARTLSR_RDR, 1b + ldr w0, [x0, #UARTRX] + ret +getc_error: + mov w0, #-1 + ret +endfunc console_core_getc |