diff options
Diffstat (limited to 'drivers/nxp/console/16550_console.S')
| -rw-r--r-- | drivers/nxp/console/16550_console.S | 319 |
1 files changed, 319 insertions, 0 deletions
diff --git a/drivers/nxp/console/16550_console.S b/drivers/nxp/console/16550_console.S new file mode 100644 index 0000000..b5617a3 --- /dev/null +++ b/drivers/nxp/console/16550_console.S @@ -0,0 +1,319 @@ +/* + * Copyright (c) 2021, ARM Limited and Contributors. All rights reserved. + * + * SPDX-License-Identifier: BSD-3-Clause + */ + +#include <arch.h> +#include <asm_macros.S> +#include <assert_macros.S> +#include <console_macros.S> + +/* UART16550 Registers */ +#define UARTTX 0x0 +#define UARTRX 0x0 +#define UARTDLL 0x0 +#define UARTIER 0x1 +#define UARTDLLM 0x1 +#define UARTFCR 0x2 +#define UARTLCR 0x3 +#define UARTLSR 0x5 +#define UARTMCR 0x4 + +/* FIFO Control Register bits */ +#define UARTFCR_FIFOMD_16450 (0 << 6) +#define UARTFCR_FIFOMD_16550 (1 << 6) +#define UARTFCR_RXTRIG_1 (0 << 6) +#define UARTFCR_RXTRIG_4 (1 << 6) +#define UARTFCR_RXTRIG_8 (2 << 6) +#define UARTFCR_RXTRIG_16 (3 << 6) +#define UARTFCR_TXTRIG_1 (0 << 4) +#define UARTFCR_TXTRIG_4 (1 << 4) +#define UARTFCR_TXTRIG_8 (2 << 4) +#define UARTFCR_TXTRIG_16 (3 << 4) +#define UARTFCR_DMAEN (1 << 3) /* Enable DMA mode */ +#define UARTFCR_TXCLR (1 << 2) /* Clear contents of Tx FIFO */ +#define UARTFCR_RXCLR (1 << 1) /* Clear contents of Rx FIFO */ +#define UARTFCR_FIFOEN (1 << 0) /* Enable the Tx/Rx FIFO */ +#define UARTFCR_64FIFO (1 << 5) + +/* Line Control Register bits */ +#define UARTLCR_DLAB (1 << 7) /* Divisor Latch Access */ +#define UARTLCR_SETB (1 << 6) /* Set BREAK Condition */ +#define UARTLCR_SETP (1 << 5) /* Set Parity to LCR[4] */ +#define UARTLCR_EVEN (1 << 4) /* Even Parity Format */ +#define UARTLCR_PAR (1 << 3) /* Parity */ +#define UARTLCR_STOP (1 << 2) /* Stop Bit */ +#define UARTLCR_WORDSZ_5 0 /* Word Length of 5 */ +#define UARTLCR_WORDSZ_6 1 /* Word Length of 6 */ +#define UARTLCR_WORDSZ_7 2 /* Word Length of 7 */ +#define UARTLCR_WORDSZ_8 3 /* Word Length of 8 */ + +/* Line Status Register bits */ +#define UARTLSR_RXFIFOEMT (1 << 9) /* Rx Fifo Empty */ +#define UARTLSR_TXFIFOFULL (1 << 8) /* Tx Fifo Full */ +#define UARTLSR_RXFIFOERR (1 << 7) /* Rx Fifo Error */ +#define UARTLSR_TEMT (1 << 6) /* Tx Shift Register Empty */ +#define UARTLSR_THRE (1 << 5) /* Tx Holding Register Empty */ +#define UARTLSR_BRK (1 << 4) /* Break Condition Detected */ +#define UARTLSR_FERR (1 << 3) /* Framing Error */ +#define UARTLSR_PERR (1 << 3) /* Parity Error */ +#define UARTLSR_OVRF (1 << 2) /* Rx Overrun Error */ +#define UARTLSR_RDR (1 << 2) /* Rx Data Ready */ + +#define CONSOLE_T_16550_BASE CONSOLE_T_BASE + + /* + * "core" functions are low-level implementations that don't require + * writable memory and are thus safe to call in BL1 crash context. + */ + .globl nxp_console_16550_core_init + .globl nxp_console_16550_core_putc + .globl nxp_console_16550_core_getc + .globl nxp_console_16550_core_flush + + .globl console_16550_putc + .globl console_16550_getc + .globl console_16550_flush + + /* ----------------------------------------------- + * int nxp_console_16550_core_init(uintptr_t 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, 0 on error + * Clobber list : x1, x2, x3 + * ----------------------------------------------- + */ +func nxp_console_16550_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 */ + ldrb w3, [x0, #UARTLCR] + orr w3, w3, #UARTLCR_DLAB + strb w3, [x0, #UARTLCR] /* enable DLL, DLLM programming */ + strb w1, [x0, #UARTDLL] /* program DLL */ + strb w2, [x0, #UARTDLLM] /* program DLLM */ + mov w2, #~UARTLCR_DLAB + and w3, w3, w2 + strb w3, [x0, #UARTLCR] /* disable DLL, DLLM programming */ + + /* 8n1 */ + mov w3, #3 + strb w3, [x0, #UARTLCR] + /* no interrupt */ + mov w3, #0 + strb w3, [x0, #UARTIER] + /* enable fifo, DMA */ + mov w3, #(UARTFCR_FIFOEN |UARTFCR_TXCLR | UARTFCR_RXCLR) + strb w3, [x0, #UARTFCR] + /* DTR + RTS */ + mov w3, #3 + str w3, [x0, #UARTMCR] + mov w0, #1 + ret +init_fail: + mov w0, #0 + ret +endfunc nxp_console_16550_core_init + + .globl nxp_console_16550_register + + /* ----------------------------------------------- + * int nxp_console_16550_register(uintptr_t baseaddr, + * uint32_t clock, uint32_t baud, + * console_t *console); + * Function to initialize and register a new 16550 + * console. Storage passed in for the console struct + * *must* be persistent (i.e. not from the stack). + * If w1 (UART clock) is 0, initialisation will be + * skipped, relying on previous code to have done + * this already. w2 is ignored then as well. + * In: x0 - UART register base address + * w1 - UART clock in Hz + * w2 - Baud rate (ignored if w1 is 0) + * x3 - pointer to empty console_t struct + * Out: return 1 on success, 0 on error + * Clobber list : x0, x1, x2, x6, x7, x14 + * ----------------------------------------------- + */ +func nxp_console_16550_register + mov x7, x30 + mov x6, x3 + cbz x6, register_fail + str x0, [x6, #CONSOLE_T_16550_BASE] + + /* A clock rate of zero means to skip the initialisation. */ + cbz w1, register_16550 + + bl nxp_console_16550_core_init + cbz x0, register_fail + +register_16550: + mov x0, x6 + mov x30, x7 + finish_console_register 16550 putc=1, getc=ENABLE_CONSOLE_GETC, flush=1 + +register_fail: + ret x7 +endfunc nxp_console_16550_register + + /* -------------------------------------------------------- + * int console_16550_core_putc(int c, uintptr_t 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 nxp_console_16550_core_putc +#if ENABLE_ASSERTIONS + cmp x1, #0 + ASM_ASSERT(ne) +#endif /* ENABLE_ASSERTIONS */ + + /* Prepend '\r' to '\n' */ + cmp w0, #'\n' + b.ne 2f + /* Check if the transmit FIFO is full */ +1: ldrb w2, [x1, #UARTLSR] + and w2, w2, #UARTLSR_THRE /* #(UARTLSR_TEMT | UARTLSR_THRE)*/ + cmp w2, #(UARTLSR_THRE) + b.ne 1b + mov w2, #'\r' + strb w2, [x1, #UARTTX] + ldrb w2, [x1, #UARTFCR] + orr w2, w2, #UARTFCR_TXCLR + + /* Check if the transmit FIFO is full */ +2: ldrb w2, [x1, #UARTLSR] + and w2, w2, #(UARTLSR_THRE) + cmp w2, #(UARTLSR_THRE) + b.ne 2b + strb w0, [x1, #UARTTX] + ret +endfunc nxp_console_16550_core_putc + + /* -------------------------------------------------------- + * int console_16550_putc(int c, console_t *console) + * 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 - pointer to console_t structure + * Out : return -1 on error else return character. + * Clobber list : x2 + * -------------------------------------------------------- + */ +func console_16550_putc +#if ENABLE_ASSERTIONS + cmp x1, #0 + ASM_ASSERT(ne) +#endif /* ENABLE_ASSERTIONS */ + ldr x1, [x1, #CONSOLE_T_16550_BASE] + b nxp_console_16550_core_putc +endfunc console_16550_putc + + /* --------------------------------------------- + * int console_16550_core_getc(uintptr_t base_addr) + * Function to get a character from the console. + * It returns the character grabbed on success + * or -1 on if no character is available. + * In : x0 - console base address + * Out : w0 - character if available, else -1 + * Clobber list : x0, x1 + * --------------------------------------------- + */ +func nxp_console_16550_core_getc +#if ENABLE_ASSERTIONS + cmp x0, #0 + ASM_ASSERT(ne) +#endif /* ENABLE_ASSERTIONS */ + + /* Check if the receive FIFO is empty */ +1: ldrb w1, [x0, #UARTLSR] + tbz w1, #UARTLSR_RDR, 1b + ldrb w0, [x0, #UARTRX] + ret +no_char: + mov w0, #ERROR_NO_PENDING_CHAR + ret +endfunc nxp_console_16550_core_getc + + /* --------------------------------------------- + * int console_16550_getc(console_t *console) + * Function to get a character from the console. + * It returns the character grabbed on success + * or -1 on if no character is available. + * In : x0 - pointer to console_t structure + * Out : w0 - character if available, else -1 + * Clobber list : x0, x1 + * --------------------------------------------- + */ +func console_16550_getc +#if ENABLE_ASSERTIONS + cmp x1, #0 + ASM_ASSERT(ne) +#endif /* ENABLE_ASSERTIONS */ + ldr x0, [x0, #CONSOLE_T_16550_BASE] + b nxp_console_16550_core_getc +endfunc console_16550_getc + + /* --------------------------------------------- + * int console_16550_core_flush(uintptr_t base_addr) + * Function to force a write of all buffered + * data that hasn't been output. + * In : x0 - console base address + * Out : return -1 on error else return 0. + * Clobber list : x0, x1 + * --------------------------------------------- + */ +func nxp_console_16550_core_flush +#if ENABLE_ASSERTIONS + cmp x0, #0 + ASM_ASSERT(ne) +#endif /* ENABLE_ASSERTIONS */ + + /* Loop until the transmit FIFO is empty */ +1: ldrb w1, [x0, #UARTLSR] + and w1, w1, #(UARTLSR_THRE) + cmp w1, #(UARTLSR_THRE) + b.ne 1b + + mov w0, #0 + ret +endfunc nxp_console_16550_core_flush + + /* --------------------------------------------- + * int console_16550_flush(console_t *console) + * Function to force a write of all buffered + * data that hasn't been output. + * In : x0 - pointer to console_t structure + * Out : return -1 on error else return 0. + * Clobber list : x0, x1 + * --------------------------------------------- + */ +func console_16550_flush +#if ENABLE_ASSERTIONS + cmp x0, #0 + ASM_ASSERT(ne) +#endif /* ENABLE_ASSERTIONS */ + ldr x0, [x0, #CONSOLE_T_16550_BASE] + b nxp_console_16550_core_flush +endfunc console_16550_flush |