1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * arch/powerpc/platforms/embedded6xx/usbgecko_udbg.c
4 *
5 * udbg serial input/output routines for the USB Gecko adapter.
6 * Copyright (C) 2008-2009 The GameCube Linux Team
7 * Copyright (C) 2008,2009 Albert Herranz
8 */
9
10 #include <linux/of_address.h>
11
12 #include <mm/mmu_decl.h>
13
14 #include <asm/io.h>
15 #include <asm/udbg.h>
16 #include <asm/fixmap.h>
17
18 #include "usbgecko_udbg.h"
19
20
21 #define EXI_CLK_32MHZ 5
22
23 #define EXI_CSR 0x00
24 #define EXI_CSR_CLKMASK (0x7<<4)
25 #define EXI_CSR_CLK_32MHZ (EXI_CLK_32MHZ<<4)
26 #define EXI_CSR_CSMASK (0x7<<7)
27 #define EXI_CSR_CS_0 (0x1<<7) /* Chip Select 001 */
28
29 #define EXI_CR 0x0c
30 #define EXI_CR_TSTART (1<<0)
31 #define EXI_CR_WRITE (1<<2)
32 #define EXI_CR_READ_WRITE (2<<2)
33 #define EXI_CR_TLEN(len) (((len)-1)<<4)
34
35 #define EXI_DATA 0x10
36
37 #define UG_READ_ATTEMPTS 100
38 #define UG_WRITE_ATTEMPTS 100
39
40
41 static void __iomem *ug_io_base;
42
43 /*
44 * Performs one input/output transaction between the exi host and the usbgecko.
45 */
46 static u32 ug_io_transaction(u32 in)
47 {
48 u32 __iomem *csr_reg = ug_io_base + EXI_CSR;
49 u32 __iomem *data_reg = ug_io_base + EXI_DATA;
50 u32 __iomem *cr_reg = ug_io_base + EXI_CR;
51 u32 csr, data, cr;
52
53 /* select */
54 csr = EXI_CSR_CLK_32MHZ | EXI_CSR_CS_0;
55 out_be32(csr_reg, csr);
56
57 /* read/write */
58 data = in;
59 out_be32(data_reg, data);
60 cr = EXI_CR_TLEN(2) | EXI_CR_READ_WRITE | EXI_CR_TSTART;
61 out_be32(cr_reg, cr);
62
63 while (in_be32(cr_reg) & EXI_CR_TSTART)
64 barrier();
65
66 /* deselect */
67 out_be32(csr_reg, 0);
68
69 /* result */
70 data = in_be32(data_reg);
71
72 return data;
73 }
74
75 /*
76 * Returns true if an usbgecko adapter is found.
77 */
78 static int ug_is_adapter_present(void)
79 {
80 if (!ug_io_base)
81 return 0;
82
83 return ug_io_transaction(0x90000000) == 0x04700000;
84 }
85
86 /*
87 * Returns true if the TX fifo is ready for transmission.
88 */
89 static int ug_is_txfifo_ready(void)
90 {
91 return ug_io_transaction(0xc0000000) & 0x04000000;
92 }
93
94 /*
95 * Tries to transmit a character.
96 * If the TX fifo is not ready the result is undefined.
97 */
98 static void ug_raw_putc(char ch)
99 {
100 ug_io_transaction(0xb0000000 | (ch << 20));
101 }
102
103 /*
104 * Transmits a character.
105 * It silently fails if the TX fifo is not ready after a number of retries.
106 */
107 static void ug_putc(char ch)
108 {
109 int count = UG_WRITE_ATTEMPTS;
110
111 if (!ug_io_base)
112 return;
113
114 if (ch == '\n')
115 ug_putc('\r');
116
117 while (!ug_is_txfifo_ready() && count--)
118 barrier();
119 if (count >= 0)
120 ug_raw_putc(ch);
121 }
122
123 /*
124 * Returns true if the RX fifo is ready for transmission.
125 */
126 static int ug_is_rxfifo_ready(void)
127 {
128 return ug_io_transaction(0xd0000000) & 0x04000000;
129 }
130
131 /*
132 * Tries to receive a character.
133 * If a character is unavailable the function returns -1.
134 */
135 static int ug_raw_getc(void)
136 {
137 u32 data = ug_io_transaction(0xa0000000);
138 if (data & 0x08000000)
139 return (data >> 16) & 0xff;
140 else
141 return -1;
142 }
143
144 /*
145 * Receives a character.
146 * It fails if the RX fifo is not ready after a number of retries.
147 */
148 static int ug_getc(void)
149 {
150 int count = UG_READ_ATTEMPTS;
151
152 if (!ug_io_base)
153 return -1;
154
155 while (!ug_is_rxfifo_ready() && count--)
156 barrier();
157 return ug_raw_getc();
158 }
159
160 /*
161 * udbg functions.
162 *
163 */
164
165 /*
166 * Transmits a character.
167 */
168 static void ug_udbg_putc(char ch)
169 {
170 ug_putc(ch);
171 }
172
173 /*
174 * Receives a character. Waits until a character is available.
175 */
176 static int ug_udbg_getc(void)
177 {
178 int ch;
179
180 while ((ch = ug_getc()) == -1)
181 barrier();
182 return ch;
183 }
184
185 /*
186 * Receives a character. If a character is not available, returns -1.
187 */
188 static int ug_udbg_getc_poll(void)
189 {
190 if (!ug_is_rxfifo_ready())
191 return -1;
192 return ug_getc();
193 }
194
195 /*
196 * Checks if a USB Gecko adapter is inserted in any memory card slot.
197 */
198 static void __iomem *__init ug_udbg_probe(void __iomem *exi_io_base)
199 {
200 int i;
201
202 /* look for a usbgecko on memcard slots A and B */
203 for (i = 0; i < 2; i++) {
204 ug_io_base = exi_io_base + 0x14 * i;
205 if (ug_is_adapter_present())
206 break;
207 }
208 if (i == 2)
209 ug_io_base = NULL;
210 return ug_io_base;
211
212 }
213
214 /*
215 * USB Gecko udbg support initialization.
216 */
217 void __init ug_udbg_init(void)
218 {
219 struct device_node *np;
220 void __iomem *exi_io_base;
221
222 if (ug_io_base)
223 udbg_printf("%s: early -> final\n", __func__);
224
225 np = of_find_compatible_node(NULL, NULL, "nintendo,flipper-exi");
226 if (!np) {
227 udbg_printf("%s: EXI node not found\n", __func__);
228 goto out;
229 }
230
231 exi_io_base = of_iomap(np, 0);
232 if (!exi_io_base) {
233 udbg_printf("%s: failed to setup EXI io base\n", __func__);
234 goto done;
235 }
236
237 if (!ug_udbg_probe(exi_io_base)) {
238 udbg_printf("usbgecko_udbg: not found\n");
239 iounmap(exi_io_base);
240 } else {
241 udbg_putc = ug_udbg_putc;
242 udbg_getc = ug_udbg_getc;
243 udbg_getc_poll = ug_udbg_getc_poll;
244 udbg_printf("usbgecko_udbg: ready\n");
245 }
246
247 done:
248 of_node_put(np);
249 out:
250 return;
251 }
252
253 #ifdef CONFIG_PPC_EARLY_DEBUG_USBGECKO
254
255 static phys_addr_t __init ug_early_grab_io_addr(void)
256 {
257 #if defined(CONFIG_GAMECUBE)
258 return 0x0c000000;
259 #elif defined(CONFIG_WII)
260 return 0x0d000000;
261 #else
262 #error Invalid platform for USB Gecko based early debugging.
263 #endif
264 }
265
266 /*
267 * USB Gecko early debug support initialization for udbg.
268 */
269 void __init udbg_init_usbgecko(void)
270 {
271 void __iomem *early_debug_area;
272 void __iomem *exi_io_base;
273
274 /*
275 * At this point we have a BAT already setup that enables I/O
276 * to the EXI hardware.
277 *
278 * The BAT uses a virtual address range reserved at the fixmap.
279 * This must match the virtual address configured in
280 * head_32.S:setup_usbgecko_bat().
281 */
282 early_debug_area = (void __iomem *)__fix_to_virt(FIX_EARLY_DEBUG_BASE);
283 exi_io_base = early_debug_area + 0x00006800;
284
285 /* try to detect a USB Gecko */
286 if (!ug_udbg_probe(exi_io_base))
287 return;
288
289 /* we found a USB Gecko, load udbg hooks */
290 udbg_putc = ug_udbg_putc;
291 udbg_getc = ug_udbg_getc;
292 udbg_getc_poll = ug_udbg_getc_poll;
293
294 /*
295 * Prepare again the same BAT for MMU_init.
296 * This allows udbg I/O to continue working after the MMU is
297 * turned on for real.
298 * It is safe to continue using the same virtual address as it is
299 * a reserved fixmap area.
300 */
301 setbat(1, (unsigned long)early_debug_area,
302 ug_early_grab_io_addr(), 128*1024, PAGE_KERNEL_NCG);
303 }
304
305 #endif /* CONFIG_PPC_EARLY_DEBUG_USBGECKO */
306
307
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