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/*
* Copyright (c) 2021, Stephan Gerhold <stephan@gerhold.net>
*
* Based on aarch64/skeleton_console.S:
* Copyright (c) 2015-2020, 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 2 /* TX FIFO has space */
#define UART_DM_SR_TXEMT_BIT 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 : x0 - pointer to empty console_t structure
* x1 - base address
* Out: x0 - 1 on success, 0 on error
* Clobber list : x0 - x7
* -----------------------------------------------------------
*/
func console_uartdm_register
str x1, [x0, #CONSOLE_T_BASE]
mov x7, lr
bl console_uartdm_core_init
mov lr, x7
/* 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 : x0 - unused
* x1 - base address
* Out: void
* Clobber list : x1, x2, x3
* -----------------------------------------------------------
*/
func console_uartdm_core_init
/* Reset receiver */
mov w3, #UART_DM_CR_RESET_RX
str w3, [x1, #UART_DM_CR]
/* Reset transmitter */
mov w3, #UART_DM_CR_RESET_TX
str w3, [x1, #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 w3, #UART_DM_DMEN_TX_SC
str w3, [x1, #UART_DM_DMEN]
/* Enable transmitter */
mov w3, #UART_DM_CR_TX_ENABLE
str w3, [x1, #UART_DM_CR]
ret
endfunc console_uartdm_core_init
/* -----------------------------------------------------------
* int console_uartdm_putc(int c, console_t *console)
* Function to output a character over the console.
* In : w0 - character to be printed
* x1 - pointer to console_t struct
* Out: w0 - printed character on success, < 0 on error.
* Clobber list : x0, x1, x2
* -----------------------------------------------------------
*/
func console_uartdm_putc
ldr x1, [x1, #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 : w0 - character to be printed
* x1 - base address
* Out: w0 - printed character on success, < 0 on error.
* Clobber list : x2
* -----------------------------------------------------------
*/
func console_uartdm_core_putc
1: /* Loop until TX FIFO has space */
ldr w2, [x1, #UART_DM_SR]
tbz w2, #UART_DM_SR_TXRDY_BIT, 1b
/* Write character to FIFO */
str w0, [x1, #UART_DM_TF]
ret
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 : x0 - pointer to console_t struct
* Out: void
* Clobber list : x0, x1, x2, x3, x4, x5
* -----------------------------------------------------------
*/
func console_uartdm_flush
ldr x1, [x0, #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 : x0 - unused
* x1 - base address
* Out: void
* Clobber list : x2
* -----------------------------------------------------------
*/
func console_uartdm_core_flush
1: /* Loop until TX FIFO is empty */
ldr w2, [x1, #UART_DM_SR]
tbz w2, #UART_DM_SR_TXEMT_BIT, 1b
ret
endfunc console_uartdm_core_flush
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