aboutsummaryrefslogtreecommitdiff
path: root/drivers/nxp/console/16550_console.S
blob: 044d3d0740c427e8d8ef116642656796bb172fc8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
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=1, 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