1/*
2 * Copyright (c) 2015-2020, ARM Limited and Contributors. All rights reserved.
3 *
4 * SPDX-License-Identifier: BSD-3-Clause
5 */
6
7#include <arch.h>
8#include <asm_macros.S>
9#include <assert_macros.S>
10#include <console_macros.S>
11#include <drivers/ti/uart/uart_16550.h>
12
13	/*
14	 * "core" functions are low-level implementations that don't require
15	 * writable memory and are thus safe to call in BL1 crash context.
16	 */
17	.globl console_16550_core_init
18	.globl console_16550_core_putc
19	.globl console_16550_core_getc
20	.globl console_16550_core_flush
21
22	.globl console_16550_putc
23	.globl console_16550_getc
24	.globl console_16550_flush
25
26	/* -----------------------------------------------
27	 * int console_16550_core_init(uintptr_t base_addr,
28	 * unsigned int uart_clk, unsigned int baud_rate)
29	 * Function to initialize the console without a
30	 * C Runtime to print debug information. This
31	 * function will be accessed by console_init and
32	 * crash reporting.
33	 * In: r0 - console base address
34	 *     r1 - Uart clock in Hz
35	 *     r2 - Baud rate
36	 * Out: return 1 on success, 0 on error
37	 * Clobber list : r1, r2, r3
38	 * -----------------------------------------------
39	 */
40func console_16550_core_init
41	/* Check the input base address */
42	cmp	r0, #0
43	beq	init_fail
44	/* Check baud rate and uart clock for sanity */
45	cmp	r1, #0
46	beq	init_fail
47	cmp	r2, #0
48	beq	init_fail
49
50	/* Program the baudrate */
51	/* Divisor =  Uart clock / (16 * baudrate) */
52	lsl	r2, r2, #4
53	udiv	r2, r1, r2
54	and	r1, r2, #0xff		/* w1 = DLL */
55	lsr	r2, r2, #8
56	and	r2, r2, #0xff		/* w2 = DLLM */
57	ldr	r3, [r0, #UARTLCR]
58	orr	r3, r3, #UARTLCR_DLAB
59	str	r3, [r0, #UARTLCR]	/* enable DLL, DLLM programming */
60	str	r1, [r0, #UARTDLL]	/* program DLL */
61	str	r2, [r0, #UARTDLLM]	/* program DLLM */
62	mov	r2, #~UARTLCR_DLAB
63	and	r3, r3, r2
64	str	r3, [r0, #UARTLCR]	/* disable DLL, DLLM programming */
65
66	/* 8n1 */
67	mov	r3, #3
68	str	r3, [r0, #UARTLCR]
69	/* no interrupt */
70	mov	r3, #0
71	str	r3, [r0, #UARTIER]
72#ifdef TI_16550_MDR_QUIRK
73	/* UART must be enabled on some platforms via the MDR register */
74	str	r3, [r0, #UARTMDR1]
75#endif /* TI_16550_MDR_QUIRK */
76	/* enable fifo, DMA */
77	mov	r3, #(UARTFCR_FIFOEN | UARTFCR_DMAEN)
78	str	r3, [r0, #UARTFCR]
79	/* DTR + RTS */
80	mov	r3, #3
81	str	r3, [r0, #UARTMCR]
82	mov	r0, #1
83	bx	lr
84init_fail:
85	mov	r0, #0
86	bx	lr
87endfunc console_16550_core_init
88
89	.globl console_16550_register
90
91	/* -------------------------------------------------------
92	 * int console_16550_register(uintptr_t baseaddr,
93	 *     uint32_t clock, uint32_t baud,
94	 *     console_t *console);
95	 * Function to initialize and register a new 16550
96	 * console. Storage passed in for the console struct
97	 * *must* be persistent (i.e. not from the stack).
98	 * If r1 (UART clock) is 0, initialisation will be
99         * skipped, relying on previous code to have done
100         * this already. r2 is ignored then as well.
101	 * In: r0 - UART register base address
102	 *     r1 - UART clock in Hz
103	 *     r2 - Baud rate (ignored if r1 is 0)
104	 *     r3 - pointer to empty console_t struct
105	 * Out: return 1 on success, 0 on error
106	 * Clobber list : r0, r1, r2
107	 * -------------------------------------------------------
108	 */
109func console_16550_register
110	push	{r4, lr}
111	mov	r4, r3
112	cmp	r4, #0
113	beq	register_fail
114	str	r0, [r4, #CONSOLE_T_BASE]
115
116	/* A clock rate of zero means to skip the initialisation. */
117	cmp	r1, #0
118	beq	register_16550
119
120	bl	console_16550_core_init
121	cmp	r0, #0
122	beq	register_fail
123
124register_16550:
125	mov	r0, r4
126	pop	{r4, lr}
127	finish_console_register 16550 putc=1, getc=1, flush=1
128
129register_fail:
130	pop	{r4, pc}
131endfunc console_16550_register
132
133	/* --------------------------------------------------------
134	 * int console_16550_core_putc(int c, uintptr_t base_addr)
135	 * Function to output a character over the console. It
136	 * returns the character printed on success or -1 on error.
137	 * In : r0 - character to be printed
138	 *      r1 - console base address
139	 * Out : return -1 on error else return character.
140	 * Clobber list : r2
141	 * --------------------------------------------------------
142	 */
143func console_16550_core_putc
144#if ENABLE_ASSERTIONS
145	cmp	r1, #0
146	ASM_ASSERT(ne)
147#endif /* ENABLE_ASSERTIONS */
148
149	/* Prepend '\r' to '\n' */
150	cmp	r0, #0xA
151	bne	2f
152	/* Check if the transmit FIFO is full */
1531:	ldr	r2, [r1, #UARTLSR]
154	and	r2, r2, #(UARTLSR_TEMT | UARTLSR_THRE)
155	cmp	r2, #(UARTLSR_TEMT | UARTLSR_THRE)
156	bne	1b
157	mov	r2, #0xD		/* '\r' */
158	str	r2, [r1, #UARTTX]
159
160	/* Check if the transmit FIFO is full */
1612:	ldr	r2, [r1, #UARTLSR]
162	and	r2, r2, #(UARTLSR_TEMT | UARTLSR_THRE)
163	cmp	r2, #(UARTLSR_TEMT | UARTLSR_THRE)
164	bne	2b
165	str	r0, [r1, #UARTTX]
166	bx	lr
167endfunc console_16550_core_putc
168
169	/* --------------------------------------------------------
170	 * int console_16550_putc(int c, console_t *console)
171	 * Function to output a character over the console. It
172	 * returns the character printed on success or -1 on error.
173	 * In : r0 - character to be printed
174	 *      r1 - pointer to console_t structure
175	 * Out : return -1 on error else return character.
176	 * Clobber list : r2
177	 * --------------------------------------------------------
178	 */
179func console_16550_putc
180#if ENABLE_ASSERTIONS
181	cmp	r1, #0
182	ASM_ASSERT(ne)
183#endif /* ENABLE_ASSERTIONS */
184	ldr	r1, [r1, #CONSOLE_T_BASE]
185	b	console_16550_core_putc
186endfunc console_16550_putc
187
188	/* ---------------------------------------------
189	 * int console_16550_core_getc(uintptr_t base_addr)
190	 * Function to get a character from the console.
191	 * It returns the character grabbed on success
192	 * or -1 on if no character is available.
193	 * In :  r0 - console base address
194	 * Clobber list : r0, r1
195	 * ---------------------------------------------
196	 */
197func console_16550_core_getc
198#if ENABLE_ASSERTIONS
199	cmp	r0, #0
200	ASM_ASSERT(ne)
201#endif /* ENABLE_ASSERTIONS */
202
203	/* Check if the receive FIFO is empty */
2041:	ldr	r1, [r0, #UARTLSR]
205	tst	r1, #UARTLSR_RDR_BIT
206	beq	no_char
207	ldr	r1, [r0, #UARTRX]
208	mov	r0, r1
209	bx	lr
210no_char:
211	mov	r0, #ERROR_NO_PENDING_CHAR
212	bx	lr
213endfunc console_16550_core_getc
214
215	/* ---------------------------------------------
216	 * int console_16550_getc(console_t *console)
217	 * Function to get a character from the console.
218	 * It returns the character grabbed on success
219	 * or -1 on if no character is available.
220	 * In :  r0 - pointer to console_t stucture
221	 * Out : r0 - character if available, else -1
222	 * Clobber list : r0, r1
223	 * ---------------------------------------------
224	 */
225func console_16550_getc
226#if ENABLE_ASSERTIONS
227	cmp	r0, #0
228	ASM_ASSERT(ne)
229#endif /* ENABLE_ASSERTIONS */
230	ldr	r0, [r0, #CONSOLE_T_BASE]
231	b	console_16550_core_getc
232endfunc console_16550_getc
233
234	/* ---------------------------------------------
235	 * void console_16550_core_flush(uintptr_t base_addr)
236	 * Function to force a write of all buffered
237	 * data that hasn't been output.
238	 * In : r0 - console base address
239	 * Out : void.
240	 * Clobber list : r0, r1
241	 * ---------------------------------------------
242	 */
243func console_16550_core_flush
244#if ENABLE_ASSERTIONS
245	cmp	r0, #0
246	ASM_ASSERT(ne)
247#endif /* ENABLE_ASSERTIONS */
248
249	/* Loop until the transmit FIFO is empty */
2501:	ldr	r1, [r0, #UARTLSR]
251	and	r1, r1, #(UARTLSR_TEMT | UARTLSR_THRE)
252	cmp	r1, #(UARTLSR_TEMT | UARTLSR_THRE)
253	bne	1b
254
255	bx	lr
256endfunc console_16550_core_flush
257
258	/* ---------------------------------------------
259	 * void console_16550_flush(console_t *console)
260	 * Function to force a write of all buffered
261	 * data that hasn't been output.
262	 * In : r0 - pointer to console_t structure
263	 * Out : void
264	 * Clobber list : r0, r1
265	 * ---------------------------------------------
266	 */
267func console_16550_flush
268#if ENABLE_ASSERTIONS
269	cmp	r0, #0
270	ASM_ASSERT(ne)
271#endif /* ENABLE_ASSERTIONS */
272	ldr	r0, [r0, #CONSOLE_T_BASE]
273	b	console_16550_core_flush
274endfunc console_16550_flush
275