1/*
2 * Copyright (c) 2021, 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
12/* UART16550 Registers */
13#define UARTTX			0x0
14#define UARTRX			0x0
15#define UARTDLL			0x0
16#define UARTIER			0x1
17#define UARTDLLM		0x1
18#define UARTFCR			0x2
19#define UARTLCR			0x3
20#define UARTLSR			0x5
21#define UARTMCR                 0x4
22
23/* FIFO Control Register bits */
24#define UARTFCR_FIFOMD_16450	(0 << 6)
25#define UARTFCR_FIFOMD_16550	(1 << 6)
26#define UARTFCR_RXTRIG_1	(0 << 6)
27#define UARTFCR_RXTRIG_4	(1 << 6)
28#define UARTFCR_RXTRIG_8	(2 << 6)
29#define UARTFCR_RXTRIG_16	(3 << 6)
30#define UARTFCR_TXTRIG_1	(0 << 4)
31#define UARTFCR_TXTRIG_4	(1 << 4)
32#define UARTFCR_TXTRIG_8	(2 << 4)
33#define UARTFCR_TXTRIG_16	(3 << 4)
34#define UARTFCR_DMAEN		(1 << 3)	/* Enable DMA mode */
35#define UARTFCR_TXCLR		(1 << 2)	/* Clear contents of Tx FIFO */
36#define UARTFCR_RXCLR		(1 << 1)	/* Clear contents of Rx FIFO */
37#define UARTFCR_FIFOEN		(1 << 0)	/* Enable the Tx/Rx FIFO */
38#define UARTFCR_64FIFO          (1 << 5)
39
40/* Line Control Register bits */
41#define UARTLCR_DLAB		(1 << 7)	/* Divisor Latch Access */
42#define UARTLCR_SETB		(1 << 6)	/* Set BREAK Condition */
43#define UARTLCR_SETP		(1 << 5)	/* Set Parity to LCR[4] */
44#define UARTLCR_EVEN		(1 << 4)	/* Even Parity Format */
45#define UARTLCR_PAR		(1 << 3)	/* Parity */
46#define UARTLCR_STOP		(1 << 2)	/* Stop Bit */
47#define UARTLCR_WORDSZ_5	0		/* Word Length of 5 */
48#define UARTLCR_WORDSZ_6	1		/* Word Length of 6 */
49#define UARTLCR_WORDSZ_7	2		/* Word Length of 7 */
50#define UARTLCR_WORDSZ_8	3		/* Word Length of 8 */
51
52/* Line Status Register bits */
53#define UARTLSR_RXFIFOEMT	(1 << 9)	/* Rx Fifo Empty */
54#define UARTLSR_TXFIFOFULL	(1 << 8)	/* Tx Fifo Full */
55#define UARTLSR_RXFIFOERR	(1 << 7)	/* Rx Fifo Error */
56#define UARTLSR_TEMT		(1 << 6)	/* Tx Shift Register Empty */
57#define UARTLSR_THRE		(1 << 5)	/* Tx Holding Register Empty */
58#define UARTLSR_BRK		(1 << 4)	/* Break Condition Detected */
59#define UARTLSR_FERR		(1 << 3)	/* Framing Error */
60#define UARTLSR_PERR		(1 << 3)	/* Parity Error */
61#define UARTLSR_OVRF		(1 << 2)	/* Rx Overrun Error */
62#define UARTLSR_RDR		(1 << 2)	/* Rx Data Ready */
63
64#define CONSOLE_T_16550_BASE	CONSOLE_T_BASE
65
66	/*
67	 * "core" functions are low-level implementations that don't require
68	 * writable memory and are thus safe to call in BL1 crash context.
69	 */
70	.globl nxp_console_16550_core_init
71	.globl nxp_console_16550_core_putc
72	.globl nxp_console_16550_core_getc
73	.globl nxp_console_16550_core_flush
74
75	.globl console_16550_putc
76	.globl console_16550_getc
77	.globl console_16550_flush
78
79	/* -----------------------------------------------
80	 * int nxp_console_16550_core_init(uintptr_t base_addr,
81	 * unsigned int uart_clk, unsigned int baud_rate)
82	 * Function to initialize the console without a
83	 * C Runtime to print debug information. This
84	 * function will be accessed by console_init and
85	 * crash reporting.
86	 * In: x0 - console base address
87	 *     w1 - Uart clock in Hz
88	 *     w2 - Baud rate
89	 * Out: return 1 on success, 0 on error
90	 * Clobber list : x1, x2, x3
91	 * -----------------------------------------------
92	 */
93func nxp_console_16550_core_init
94	/* Check the input base address */
95	cbz	x0, init_fail
96	/* Check baud rate and uart clock for sanity */
97	cbz	w1, init_fail
98	cbz	w2, init_fail
99
100	/* Program the baudrate */
101	/* Divisor =  Uart clock / (16 * baudrate) */
102	lsl	w2, w2, #4
103	udiv	w2, w1, w2
104	and	w1, w2, #0xff		/* w1 = DLL */
105	lsr	w2, w2, #8
106	and	w2, w2, #0xff		/* w2 = DLLM */
107	ldrb	w3, [x0, #UARTLCR]
108	orr	w3, w3, #UARTLCR_DLAB
109	strb	w3, [x0, #UARTLCR]	/* enable DLL, DLLM programming */
110	strb	w1, [x0, #UARTDLL]	/* program DLL */
111	strb	w2, [x0, #UARTDLLM]	/* program DLLM */
112	mov	w2, #~UARTLCR_DLAB
113	and	w3, w3, w2
114	strb	w3, [x0, #UARTLCR]	/* disable DLL, DLLM programming */
115
116	/* 8n1 */
117	mov	w3, #3
118	strb	w3, [x0, #UARTLCR]
119	/* no interrupt */
120	mov	w3, #0
121	strb	w3, [x0, #UARTIER]
122	/* enable fifo, DMA */
123	mov	w3, #(UARTFCR_FIFOEN |UARTFCR_TXCLR | UARTFCR_RXCLR)
124	strb	w3, [x0, #UARTFCR]
125	/* DTR + RTS */
126	mov	w3, #3
127	str	w3, [x0, #UARTMCR]
128	mov	w0, #1
129	ret
130init_fail:
131	mov	w0, #0
132	ret
133endfunc nxp_console_16550_core_init
134
135	.globl nxp_console_16550_register
136
137	/* -----------------------------------------------
138	 * int nxp_console_16550_register(uintptr_t baseaddr,
139	 *     uint32_t clock, uint32_t baud,
140	 *     console_t *console);
141	 * Function to initialize and register a new 16550
142	 * console. Storage passed in for the console struct
143	 * *must* be persistent (i.e. not from the stack).
144	 * If w1 (UART clock) is 0, initialisation will be
145	 * skipped, relying on previous code to have done
146	 * this already. w2 is ignored then as well.
147	 * In: x0 - UART register base address
148	 *     w1 - UART clock in Hz
149	 *     w2 - Baud rate (ignored if w1 is 0)
150	 *     x3 - pointer to empty console_t struct
151	 * Out: return 1 on success, 0 on error
152	 * Clobber list : x0, x1, x2, x6, x7, x14
153	 * -----------------------------------------------
154	 */
155func nxp_console_16550_register
156	mov	x7, x30
157	mov	x6, x3
158	cbz	x6, register_fail
159	str	x0, [x6, #CONSOLE_T_16550_BASE]
160
161	/* A clock rate of zero means to skip the initialisation. */
162	cbz	w1, register_16550
163
164	bl	nxp_console_16550_core_init
165	cbz	x0, register_fail
166
167register_16550:
168	mov	x0, x6
169	mov	x30, x7
170	finish_console_register 16550 putc=1, getc=ENABLE_CONSOLE_GETC, flush=1
171
172register_fail:
173	ret	x7
174endfunc nxp_console_16550_register
175
176	/* --------------------------------------------------------
177	 * int console_16550_core_putc(int c, uintptr_t base_addr)
178	 * Function to output a character over the console. It
179	 * returns the character printed on success or -1 on error.
180	 * In : w0 - character to be printed
181	 *      x1 - console base address
182	 * Out : return -1 on error else return character.
183	 * Clobber list : x2
184	 * --------------------------------------------------------
185	 */
186func nxp_console_16550_core_putc
187#if ENABLE_ASSERTIONS
188	cmp	x1, #0
189	ASM_ASSERT(ne)
190#endif /* ENABLE_ASSERTIONS */
191
192	/* Prepend '\r' to '\n' */
193	cmp	w0, #'\n'
194	b.ne	2f
195	/* Check if the transmit FIFO is full */
1961:	ldrb	w2, [x1, #UARTLSR]
197	and	w2, w2, #UARTLSR_THRE        /* #(UARTLSR_TEMT | UARTLSR_THRE)*/
198	cmp	w2, #(UARTLSR_THRE)
199	b.ne	1b
200	mov	w2, #'\r'
201	strb	w2, [x1, #UARTTX]
202	ldrb	w2, [x1, #UARTFCR]
203	orr	w2, w2, #UARTFCR_TXCLR
204
205	/* Check if the transmit FIFO is full */
2062:	ldrb	w2, [x1, #UARTLSR]
207	and	w2, w2, #(UARTLSR_THRE)
208	cmp	w2, #(UARTLSR_THRE)
209	b.ne	2b
210	strb	w0, [x1, #UARTTX]
211	ret
212endfunc nxp_console_16550_core_putc
213
214	/* --------------------------------------------------------
215	 * int console_16550_putc(int c, console_t *console)
216	 * Function to output a character over the console. It
217	 * returns the character printed on success or -1 on error.
218	 * In : w0 - character to be printed
219	 *      x1 - pointer to console_t structure
220	 * Out : return -1 on error else return character.
221	 * Clobber list : x2
222	 * --------------------------------------------------------
223	 */
224func console_16550_putc
225#if ENABLE_ASSERTIONS
226	cmp	x1, #0
227	ASM_ASSERT(ne)
228#endif /* ENABLE_ASSERTIONS */
229	ldr	x1, [x1, #CONSOLE_T_16550_BASE]
230	b	nxp_console_16550_core_putc
231endfunc console_16550_putc
232
233	/* ---------------------------------------------
234	 * int console_16550_core_getc(uintptr_t base_addr)
235	 * Function to get a character from the console.
236	 * It returns the character grabbed on success
237	 * or -1 on if no character is available.
238	 * In :  x0 - console base address
239	 * Out : w0 - character if available, else -1
240	 * Clobber list : x0, x1
241	 * ---------------------------------------------
242	 */
243func nxp_console_16550_core_getc
244#if ENABLE_ASSERTIONS
245	cmp	x0, #0
246	ASM_ASSERT(ne)
247#endif /* ENABLE_ASSERTIONS */
248
249	/* Check if the receive FIFO is empty */
2501:	ldrb	w1, [x0, #UARTLSR]
251	tbz	w1, #UARTLSR_RDR, 1b
252	ldrb	w0, [x0, #UARTRX]
253	ret
254no_char:
255	mov	w0, #ERROR_NO_PENDING_CHAR
256	ret
257endfunc nxp_console_16550_core_getc
258
259	/* ---------------------------------------------
260	 * int console_16550_getc(console_t *console)
261	 * Function to get a character from the console.
262	 * It returns the character grabbed on success
263	 * or -1 on if no character is available.
264	 * In :  x0 - pointer to console_t structure
265	 * Out : w0 - character if available, else -1
266	 * Clobber list : x0, x1
267	 * ---------------------------------------------
268	 */
269func console_16550_getc
270#if ENABLE_ASSERTIONS
271	cmp	x1, #0
272	ASM_ASSERT(ne)
273#endif /* ENABLE_ASSERTIONS */
274	ldr	x0, [x0, #CONSOLE_T_16550_BASE]
275	b	nxp_console_16550_core_getc
276endfunc console_16550_getc
277
278	/* ---------------------------------------------
279	 * int console_16550_core_flush(uintptr_t base_addr)
280	 * Function to force a write of all buffered
281	 * data that hasn't been output.
282	 * In : x0 - console base address
283	 * Out : return -1 on error else return 0.
284	 * Clobber list : x0, x1
285	 * ---------------------------------------------
286	 */
287func nxp_console_16550_core_flush
288#if ENABLE_ASSERTIONS
289	cmp	x0, #0
290	ASM_ASSERT(ne)
291#endif /* ENABLE_ASSERTIONS */
292
293	/* Loop until the transmit FIFO is empty */
2941:	ldrb	w1, [x0, #UARTLSR]
295	and	w1, w1, #(UARTLSR_THRE)
296	cmp	w1, #(UARTLSR_THRE)
297	b.ne	1b
298
299	mov	w0, #0
300	ret
301endfunc nxp_console_16550_core_flush
302
303	/* ---------------------------------------------
304	 * int console_16550_flush(console_t *console)
305	 * Function to force a write of all buffered
306	 * data that hasn't been output.
307	 * In : x0 - pointer to console_t structure
308	 * Out : return -1 on error else return 0.
309	 * Clobber list : x0, x1
310	 * ---------------------------------------------
311	 */
312func console_16550_flush
313#if ENABLE_ASSERTIONS
314	cmp	x0, #0
315	ASM_ASSERT(ne)
316#endif /* ENABLE_ASSERTIONS */
317	ldr	x0, [x0, #CONSOLE_T_16550_BASE]
318	b	nxp_console_16550_core_flush
319endfunc console_16550_flush
320