1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * udbg for NS16550 compatible serial ports
4 *
5 * Copyright (C) 2001-2005 PPC 64 Team, IBM Corp
6 */
7#include <linux/types.h>
8#include <asm/udbg.h>
9#include <asm/io.h>
10#include <asm/early_ioremap.h>
11
12extern u8 real_readb(volatile u8 __iomem *addr);
13extern void real_writeb(u8 data, volatile u8 __iomem *addr);
14extern u8 real_205_readb(volatile u8 __iomem *addr);
15extern void real_205_writeb(u8 data, volatile u8 __iomem *addr);
16
17#define UART_RBR 0
18#define UART_IER 1
19#define UART_FCR 2
20#define UART_LCR 3
21#define UART_MCR 4
22#define UART_LSR 5
23#define UART_MSR 6
24#define UART_SCR 7
25#define UART_THR UART_RBR
26#define UART_IIR UART_FCR
27#define UART_DLL UART_RBR
28#define UART_DLM UART_IER
29#define UART_DLAB UART_LCR
30
31#define LSR_DR 0x01 /* Data ready */
32#define LSR_OE 0x02 /* Overrun */
33#define LSR_PE 0x04 /* Parity error */
34#define LSR_FE 0x08 /* Framing error */
35#define LSR_BI 0x10 /* Break */
36#define LSR_THRE 0x20 /* Xmit holding register empty */
37#define LSR_TEMT 0x40 /* Xmitter empty */
38#define LSR_ERR 0x80 /* Error */
39
40#define LCR_DLAB 0x80
41
42static u8 (*udbg_uart_in)(unsigned int reg);
43static void (*udbg_uart_out)(unsigned int reg, u8 data);
44
45static void udbg_uart_flush(void)
46{
47 if (!udbg_uart_in)
48 return;
49
50 /* wait for idle */
51 while ((udbg_uart_in(UART_LSR) & LSR_THRE) == 0)
52 cpu_relax();
53}
54
55static void udbg_uart_putc(char c)
56{
57 if (!udbg_uart_out)
58 return;
59
60 if (c == '\n')
61 udbg_uart_putc(c: '\r');
62 udbg_uart_flush();
63 udbg_uart_out(UART_THR, c);
64}
65
66static int udbg_uart_getc_poll(void)
67{
68 if (!udbg_uart_in)
69 return -1;
70
71 if (!(udbg_uart_in(UART_LSR) & LSR_DR))
72 return udbg_uart_in(UART_RBR);
73
74 return -1;
75}
76
77static int udbg_uart_getc(void)
78{
79 if (!udbg_uart_in)
80 return -1;
81 /* wait for char */
82 while (!(udbg_uart_in(UART_LSR) & LSR_DR))
83 cpu_relax();
84 return udbg_uart_in(UART_RBR);
85}
86
87static void __init udbg_use_uart(void)
88{
89 udbg_putc = udbg_uart_putc;
90 udbg_flush = udbg_uart_flush;
91 udbg_getc = udbg_uart_getc;
92 udbg_getc_poll = udbg_uart_getc_poll;
93}
94
95void __init udbg_uart_setup(unsigned int speed, unsigned int clock)
96{
97 unsigned int dll, base_bauds;
98
99 if (!udbg_uart_out)
100 return;
101
102 if (clock == 0)
103 clock = 1843200;
104 if (speed == 0)
105 speed = 9600;
106
107 base_bauds = clock / 16;
108 dll = base_bauds / speed;
109
110 udbg_uart_out(UART_LCR, 0x00);
111 udbg_uart_out(UART_IER, 0xff);
112 udbg_uart_out(UART_IER, 0x00);
113 udbg_uart_out(UART_LCR, LCR_DLAB);
114 udbg_uart_out(UART_DLL, dll & 0xff);
115 udbg_uart_out(UART_DLM, dll >> 8);
116 /* 8 data, 1 stop, no parity */
117 udbg_uart_out(UART_LCR, 0x3);
118 /* RTS/DTR */
119 udbg_uart_out(UART_MCR, 0x3);
120 /* Clear & enable FIFOs */
121 udbg_uart_out(UART_FCR, 0x7);
122}
123
124unsigned int __init udbg_probe_uart_speed(unsigned int clock)
125{
126 unsigned int dll, dlm, divisor, prescaler, speed;
127 u8 old_lcr;
128
129 old_lcr = udbg_uart_in(UART_LCR);
130
131 /* select divisor latch registers. */
132 udbg_uart_out(UART_LCR, old_lcr | LCR_DLAB);
133
134 /* now, read the divisor */
135 dll = udbg_uart_in(UART_DLL);
136 dlm = udbg_uart_in(UART_DLM);
137 divisor = dlm << 8 | dll;
138
139 /* check prescaling */
140 if (udbg_uart_in(UART_MCR) & 0x80)
141 prescaler = 4;
142 else
143 prescaler = 1;
144
145 /* restore the LCR */
146 udbg_uart_out(UART_LCR, old_lcr);
147
148 /* calculate speed */
149 speed = (clock / prescaler) / (divisor * 16);
150
151 /* sanity check */
152 if (speed > (clock / 16))
153 speed = 9600;
154
155 return speed;
156}
157
158static union {
159 unsigned char __iomem *mmio_base;
160 unsigned long pio_base;
161} udbg_uart;
162
163static unsigned int udbg_uart_stride = 1;
164
165static u8 udbg_uart_in_pio(unsigned int reg)
166{
167 return inb(port: udbg_uart.pio_base + (reg * udbg_uart_stride));
168}
169
170static void udbg_uart_out_pio(unsigned int reg, u8 data)
171{
172 outb(value: data, port: udbg_uart.pio_base + (reg * udbg_uart_stride));
173}
174
175void __init udbg_uart_init_pio(unsigned long port, unsigned int stride)
176{
177 if (!port)
178 return;
179 udbg_uart.pio_base = port;
180 udbg_uart_stride = stride;
181 udbg_uart_in = udbg_uart_in_pio;
182 udbg_uart_out = udbg_uart_out_pio;
183 udbg_use_uart();
184}
185
186static u8 udbg_uart_in_mmio(unsigned int reg)
187{
188 return in_8(udbg_uart.mmio_base + (reg * udbg_uart_stride));
189}
190
191static void udbg_uart_out_mmio(unsigned int reg, u8 data)
192{
193 out_8(udbg_uart.mmio_base + (reg * udbg_uart_stride), data);
194}
195
196
197void __init udbg_uart_init_mmio(void __iomem *addr, unsigned int stride)
198{
199 if (!addr)
200 return;
201 udbg_uart.mmio_base = addr;
202 udbg_uart_stride = stride;
203 udbg_uart_in = udbg_uart_in_mmio;
204 udbg_uart_out = udbg_uart_out_mmio;
205 udbg_use_uart();
206}
207
208#ifdef CONFIG_PPC_PASEMI
209
210#define UDBG_UART_PAS_ADDR ((void __iomem *)0xfcff03f8UL)
211
212static u8 udbg_uart_in_pas(unsigned int reg)
213{
214 return real_205_readb(UDBG_UART_PAS_ADDR + reg);
215}
216
217static void udbg_uart_out_pas(unsigned int reg, u8 val)
218{
219 real_205_writeb(val, UDBG_UART_PAS_ADDR + reg);
220}
221
222void __init udbg_init_pas_realmode(void)
223{
224 udbg_uart_in = udbg_uart_in_pas;
225 udbg_uart_out = udbg_uart_out_pas;
226 udbg_use_uart();
227}
228
229#endif /* CONFIG_PPC_PASEMI */
230
231#ifdef CONFIG_PPC_EARLY_DEBUG_44x
232
233#include <platforms/44x/44x.h>
234
235static u8 udbg_uart_in_44x_as1(unsigned int reg)
236{
237 return as1_readb((void __iomem *)PPC44x_EARLY_DEBUG_VIRTADDR + reg);
238}
239
240static void udbg_uart_out_44x_as1(unsigned int reg, u8 val)
241{
242 as1_writeb(val, (void __iomem *)PPC44x_EARLY_DEBUG_VIRTADDR + reg);
243}
244
245void __init udbg_init_44x_as1(void)
246{
247 udbg_uart_in = udbg_uart_in_44x_as1;
248 udbg_uart_out = udbg_uart_out_44x_as1;
249 udbg_use_uart();
250}
251
252#endif /* CONFIG_PPC_EARLY_DEBUG_44x */
253
254#ifdef CONFIG_PPC_EARLY_DEBUG_16550
255
256static void __iomem *udbg_uart_early_addr;
257
258void __init udbg_init_debug_16550(void)
259{
260 udbg_uart_early_addr = early_ioremap(CONFIG_PPC_EARLY_DEBUG_16550_PHYSADDR, 0x1000);
261 udbg_uart_init_mmio(udbg_uart_early_addr, CONFIG_PPC_EARLY_DEBUG_16550_STRIDE);
262}
263
264static int __init udbg_init_debug_16550_ioremap(void)
265{
266 void __iomem *addr;
267
268 if (!udbg_uart_early_addr)
269 return 0;
270
271 addr = ioremap(CONFIG_PPC_EARLY_DEBUG_16550_PHYSADDR, 0x1000);
272 if (WARN_ON(!addr))
273 return -ENOMEM;
274
275 udbg_uart_init_mmio(addr, CONFIG_PPC_EARLY_DEBUG_16550_STRIDE);
276 early_iounmap(udbg_uart_early_addr, 0x1000);
277 udbg_uart_early_addr = NULL;
278
279 return 0;
280}
281
282early_initcall(udbg_init_debug_16550_ioremap);
283
284#endif /* CONFIG_PPC_EARLY_DEBUG_16550 */
285

source code of linux/arch/powerpc/kernel/udbg_16550.c