diff options
Diffstat (limited to 'plat/qti/msm8916/aarch32/uartdm_console.S')
| -rw-r--r-- | plat/qti/msm8916/aarch32/uartdm_console.S | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/plat/qti/msm8916/aarch32/uartdm_console.S b/plat/qti/msm8916/aarch32/uartdm_console.S new file mode 100644 index 0000000..a19776a --- /dev/null +++ b/plat/qti/msm8916/aarch32/uartdm_console.S @@ -0,0 +1,183 @@ +/* + * Copyright (c) 2021-2023, Stephan Gerhold <stephan@gerhold.net> + * + * Based on aarch32/skeleton_console.S: + * Copyright (c) 2016-2020, ARM Limited and Contributors. All rights reserved. + * + * SPDX-License-Identifier: BSD-3-Clause + */ + +#include <asm_macros.S> +#include <console_macros.S> + +/* UART DM registers */ +#define UART_DM_DMEN 0x03c /* DMA / data packing */ +#define UART_DM_SR 0x0a4 /* status register */ +#define UART_DM_CR 0x0a8 /* command register */ +#define UART_DM_TF 0x100 /* transmit FIFO */ + +#define UART_DM_DMEN_TX_SC BIT_32(4) /* TX single character mode */ + +#define UART_DM_SR_TXRDY BIT_32(2) /* TX FIFO has space */ +#define UART_DM_SR_TXEMT BIT_32(3) /* TX FIFO is empty */ + +#define UART_DM_CR_RESET_RX (U(0x01) << 4) /* reset receiver */ +#define UART_DM_CR_RESET_TX (U(0x02) << 4) /* reset transmitter */ +#define UART_DM_CR_TX_ENABLE BIT_32(2) /* enable transmitter */ + + .globl console_uartdm_register + .globl console_uartdm_core_init + .globl console_uartdm_putc + .globl console_uartdm_core_putc + .globl console_uartdm_flush + .globl console_uartdm_core_flush + + /* ----------------------------------------------------------- + * int console_uartdm_register(console_t *console, + * uintptr_t base_addr) + * Function to initialize and register the console. The caller + * needs to pass an empty console_t structure in which *MUST* + * be allocated in persistent memory (e.g. a global or static + * local variable, *NOT* on the stack). + * In : r0 - pointer to empty console_t structure + * r1 - base address + * Out: r0 - 1 on success, 0 on error + * Clobber list : r0 - r7 + * ----------------------------------------------------------- + */ +func console_uartdm_register + str r1, [r0, #CONSOLE_T_BASE] + mov r7, lr + bl console_uartdm_core_init + mov lr, r7 + + /* Register the new console */ + finish_console_register uartdm putc=1, flush=1 +endfunc console_uartdm_register + + /* ----------------------------------------------------------- + * void console_uartdm_core_init(unused, uintptr_t base_addr) + * Function to initialize the console. + * In : r0 - unused + * r1 - base address + * Out: void + * Clobber list : r1, r2, r3 + * ----------------------------------------------------------- + */ +func console_uartdm_core_init + /* + * Try to flush remaining characters from the TX FIFO before resetting + * the transmitter. Unfortunately there is no good way to check if + * the transmitter is actually enabled (and will finish eventually), + * so use a timeout to avoid looping forever. + */ + mov r2, #65536 +1: + ldr r3, [r1, #UART_DM_SR] + tst r3, #UART_DM_SR_TXEMT + bne 2f + subs r2, r2, #1 + bne 1b + /* Timeout */ + +2: /* Reset receiver */ + mov r3, #UART_DM_CR_RESET_RX + str r3, [r1, #UART_DM_CR] + + /* Reset transmitter */ + mov r3, #UART_DM_CR_RESET_TX + str r3, [r1, #UART_DM_CR] + + /* + * Disable BAM/DMA modes but enable single-character mode for TX. + * The single character mode allows simplifying the putc implementation + * since characters can be written directly to the FIFO instead of + * having to initiate a new transfer and waiting for its completion. + */ + mov r3, #UART_DM_DMEN_TX_SC + str r3, [r1, #UART_DM_DMEN] + + /* Enable transmitter */ + mov r3, #UART_DM_CR_TX_ENABLE + str r3, [r1, #UART_DM_CR] + + bx lr +endfunc console_uartdm_core_init + + /* ----------------------------------------------------------- + * int console_uartdm_putc(int c, console_t *console) + * Function to output a character over the console. + * In : r0 - character to be printed + * r1 - pointer to console_t struct + * Out: r0 - printed character on success, < 0 on error. + * Clobber list : r0, r1, r2 + * ----------------------------------------------------------- + */ +func console_uartdm_putc + ldr r1, [r1, #CONSOLE_T_BASE] + b console_uartdm_core_putc +endfunc console_uartdm_putc + + /* ----------------------------------------------------------- + * int console_uartdm_core_putc(int c, uintptr_t base_addr) + * Function to output a character over the console. + * In : r0 - character to be printed + * r1 - base address + * Out: r0 - printed character on success, < 0 on error. + * Clobber list : r2 + * ----------------------------------------------------------- + */ +func console_uartdm_core_putc + cmp r0, #'\n' + bne 2f + +1: /* Loop until TX FIFO has space */ + ldr r2, [r1, #UART_DM_SR] + tst r2, #UART_DM_SR_TXRDY + beq 1b + + /* Prepend '\r' to '\n' */ + mov r2, #'\r' + str r2, [r1, #UART_DM_TF] + +2: /* Loop until TX FIFO has space */ + ldr r2, [r1, #UART_DM_SR] + tst r2, #UART_DM_SR_TXRDY + beq 2b + + /* Write character to FIFO */ + str r0, [r1, #UART_DM_TF] + bx lr +endfunc console_uartdm_core_putc + + /* ----------------------------------------------------------- + * void console_uartdm_flush(console_t *console) + * Function to force a write of all buffered data + * that has not been output. + * In : r0 - pointer to console_t struct + * Out: void + * Clobber list : r0, r1, r2, r3, r4, r5 + * ----------------------------------------------------------- + */ +func console_uartdm_flush + ldr r1, [r0, #CONSOLE_T_BASE] + b console_uartdm_core_flush +endfunc console_uartdm_flush + + /* ----------------------------------------------------------- + * void console_uartdm_core_flush(unused, uintptr_t base_addr) + * Function to force a write of all buffered data + * that has not been output. + * In : r0 - unused + * r1 - base address + * Out: void + * Clobber list : r2 + * ----------------------------------------------------------- + */ +func console_uartdm_core_flush +1: /* Loop until TX FIFO is empty */ + ldr r2, [r1, #UART_DM_SR] + tst r2, #UART_DM_SR_TXEMT + beq 1b + bx lr +endfunc console_uartdm_core_flush |