1 /*
2  * arch/powerpc/platforms/embedded6xx/usbgecko_udbg.c
3  *
4  * udbg serial input/output routines for the USB Gecko adapter.
5  * Copyright (C) 2008-2009 The GameCube Linux Team
6  * Copyright (C) 2008,2009 Albert Herranz
7  *
8  * This program is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU General Public License
10  * as published by the Free Software Foundation; either version 2
11  * of the License, or (at your option) any later version.
12  *
13  */
14 
15 #include <mm/mmu_decl.h>
16 
17 #include <asm/io.h>
18 #include <asm/prom.h>
19 #include <asm/udbg.h>
20 #include <asm/fixmap.h>
21 
22 #include "usbgecko_udbg.h"
23 
24 
25 #define EXI_CLK_32MHZ           5
26 
27 #define EXI_CSR                 0x00
28 #define   EXI_CSR_CLKMASK       (0x7<<4)
29 #define     EXI_CSR_CLK_32MHZ   (EXI_CLK_32MHZ<<4)
30 #define   EXI_CSR_CSMASK        (0x7<<7)
31 #define     EXI_CSR_CS_0        (0x1<<7)  /* Chip Select 001 */
32 
33 #define EXI_CR                  0x0c
34 #define   EXI_CR_TSTART         (1<<0)
35 #define   EXI_CR_WRITE		(1<<2)
36 #define   EXI_CR_READ_WRITE     (2<<2)
37 #define   EXI_CR_TLEN(len)      (((len)-1)<<4)
38 
39 #define EXI_DATA                0x10
40 
41 #define UG_READ_ATTEMPTS	100
42 #define UG_WRITE_ATTEMPTS	100
43 
44 
45 static void __iomem *ug_io_base;
46 
47 /*
48  * Performs one input/output transaction between the exi host and the usbgecko.
49  */
50 static u32 ug_io_transaction(u32 in)
51 {
52 	u32 __iomem *csr_reg = ug_io_base + EXI_CSR;
53 	u32 __iomem *data_reg = ug_io_base + EXI_DATA;
54 	u32 __iomem *cr_reg = ug_io_base + EXI_CR;
55 	u32 csr, data, cr;
56 
57 	/* select */
58 	csr = EXI_CSR_CLK_32MHZ | EXI_CSR_CS_0;
59 	out_be32(csr_reg, csr);
60 
61 	/* read/write */
62 	data = in;
63 	out_be32(data_reg, data);
64 	cr = EXI_CR_TLEN(2) | EXI_CR_READ_WRITE | EXI_CR_TSTART;
65 	out_be32(cr_reg, cr);
66 
67 	while (in_be32(cr_reg) & EXI_CR_TSTART)
68 		barrier();
69 
70 	/* deselect */
71 	out_be32(csr_reg, 0);
72 
73 	/* result */
74 	data = in_be32(data_reg);
75 
76 	return data;
77 }
78 
79 /*
80  * Returns true if an usbgecko adapter is found.
81  */
82 static int ug_is_adapter_present(void)
83 {
84 	if (!ug_io_base)
85 		return 0;
86 
87 	return ug_io_transaction(0x90000000) == 0x04700000;
88 }
89 
90 /*
91  * Returns true if the TX fifo is ready for transmission.
92  */
93 static int ug_is_txfifo_ready(void)
94 {
95 	return ug_io_transaction(0xc0000000) & 0x04000000;
96 }
97 
98 /*
99  * Tries to transmit a character.
100  * If the TX fifo is not ready the result is undefined.
101  */
102 static void ug_raw_putc(char ch)
103 {
104 	ug_io_transaction(0xb0000000 | (ch << 20));
105 }
106 
107 /*
108  * Transmits a character.
109  * It silently fails if the TX fifo is not ready after a number of retries.
110  */
111 static void ug_putc(char ch)
112 {
113 	int count = UG_WRITE_ATTEMPTS;
114 
115 	if (!ug_io_base)
116 		return;
117 
118 	if (ch == '\n')
119 		ug_putc('\r');
120 
121 	while (!ug_is_txfifo_ready() && count--)
122 		barrier();
123 	if (count >= 0)
124 		ug_raw_putc(ch);
125 }
126 
127 /*
128  * Returns true if the RX fifo is ready for transmission.
129  */
130 static int ug_is_rxfifo_ready(void)
131 {
132 	return ug_io_transaction(0xd0000000) & 0x04000000;
133 }
134 
135 /*
136  * Tries to receive a character.
137  * If a character is unavailable the function returns -1.
138  */
139 static int ug_raw_getc(void)
140 {
141 	u32 data = ug_io_transaction(0xa0000000);
142 	if (data & 0x08000000)
143 		return (data >> 16) & 0xff;
144 	else
145 		return -1;
146 }
147 
148 /*
149  * Receives a character.
150  * It fails if the RX fifo is not ready after a number of retries.
151  */
152 static int ug_getc(void)
153 {
154 	int count = UG_READ_ATTEMPTS;
155 
156 	if (!ug_io_base)
157 		return -1;
158 
159 	while (!ug_is_rxfifo_ready() && count--)
160 		barrier();
161 	return ug_raw_getc();
162 }
163 
164 /*
165  * udbg functions.
166  *
167  */
168 
169 /*
170  * Transmits a character.
171  */
172 void ug_udbg_putc(char ch)
173 {
174 	ug_putc(ch);
175 }
176 
177 /*
178  * Receives a character. Waits until a character is available.
179  */
180 static int ug_udbg_getc(void)
181 {
182 	int ch;
183 
184 	while ((ch = ug_getc()) == -1)
185 		barrier();
186 	return ch;
187 }
188 
189 /*
190  * Receives a character. If a character is not available, returns -1.
191  */
192 static int ug_udbg_getc_poll(void)
193 {
194 	if (!ug_is_rxfifo_ready())
195 		return -1;
196 	return ug_getc();
197 }
198 
199 /*
200  * Retrieves and prepares the virtual address needed to access the hardware.
201  */
202 static void __iomem *ug_udbg_setup_exi_io_base(struct device_node *np)
203 {
204 	void __iomem *exi_io_base = NULL;
205 	phys_addr_t paddr;
206 	const unsigned int *reg;
207 
208 	reg = of_get_property(np, "reg", NULL);
209 	if (reg) {
210 		paddr = of_translate_address(np, reg);
211 		if (paddr)
212 			exi_io_base = ioremap(paddr, reg[1]);
213 	}
214 	return exi_io_base;
215 }
216 
217 /*
218  * Checks if a USB Gecko adapter is inserted in any memory card slot.
219  */
220 static void __iomem *ug_udbg_probe(void __iomem *exi_io_base)
221 {
222 	int i;
223 
224 	/* look for a usbgecko on memcard slots A and B */
225 	for (i = 0; i < 2; i++) {
226 		ug_io_base = exi_io_base + 0x14 * i;
227 		if (ug_is_adapter_present())
228 			break;
229 	}
230 	if (i == 2)
231 		ug_io_base = NULL;
232 	return ug_io_base;
233 
234 }
235 
236 /*
237  * USB Gecko udbg support initialization.
238  */
239 void __init ug_udbg_init(void)
240 {
241 	struct device_node *np;
242 	void __iomem *exi_io_base;
243 
244 	if (ug_io_base)
245 		udbg_printf("%s: early -> final\n", __func__);
246 
247 	np = of_find_compatible_node(NULL, NULL, "nintendo,flipper-exi");
248 	if (!np) {
249 		udbg_printf("%s: EXI node not found\n", __func__);
250 		goto out;
251 	}
252 
253 	exi_io_base = ug_udbg_setup_exi_io_base(np);
254 	if (!exi_io_base) {
255 		udbg_printf("%s: failed to setup EXI io base\n", __func__);
256 		goto done;
257 	}
258 
259 	if (!ug_udbg_probe(exi_io_base)) {
260 		udbg_printf("usbgecko_udbg: not found\n");
261 		iounmap(exi_io_base);
262 	} else {
263 		udbg_putc = ug_udbg_putc;
264 		udbg_getc = ug_udbg_getc;
265 		udbg_getc_poll = ug_udbg_getc_poll;
266 		udbg_printf("usbgecko_udbg: ready\n");
267 	}
268 
269 done:
270 	of_node_put(np);
271 out:
272 	return;
273 }
274 
275 #ifdef CONFIG_PPC_EARLY_DEBUG_USBGECKO
276 
277 static phys_addr_t __init ug_early_grab_io_addr(void)
278 {
279 #if defined(CONFIG_GAMECUBE)
280 	return 0x0c000000;
281 #elif defined(CONFIG_WII)
282 	return 0x0d000000;
283 #else
284 #error Invalid platform for USB Gecko based early debugging.
285 #endif
286 }
287 
288 /*
289  * USB Gecko early debug support initialization for udbg.
290  */
291 void __init udbg_init_usbgecko(void)
292 {
293 	void __iomem *early_debug_area;
294 	void __iomem *exi_io_base;
295 
296 	/*
297 	 * At this point we have a BAT already setup that enables I/O
298 	 * to the EXI hardware.
299 	 *
300 	 * The BAT uses a virtual address range reserved at the fixmap.
301 	 * This must match the virtual address configured in
302 	 * head_32.S:setup_usbgecko_bat().
303 	 */
304 	early_debug_area = (void __iomem *)__fix_to_virt(FIX_EARLY_DEBUG_BASE);
305 	exi_io_base = early_debug_area + 0x00006800;
306 
307 	/* try to detect a USB Gecko */
308 	if (!ug_udbg_probe(exi_io_base))
309 		return;
310 
311 	/* we found a USB Gecko, load udbg hooks */
312 	udbg_putc = ug_udbg_putc;
313 	udbg_getc = ug_udbg_getc;
314 	udbg_getc_poll = ug_udbg_getc_poll;
315 
316 	/*
317 	 * Prepare again the same BAT for MMU_init.
318 	 * This allows udbg I/O to continue working after the MMU is
319 	 * turned on for real.
320 	 * It is safe to continue using the same virtual address as it is
321 	 * a reserved fixmap area.
322 	 */
323 	setbat(1, (unsigned long)early_debug_area,
324 	       ug_early_grab_io_addr(), 128*1024, PAGE_KERNEL_NCG);
325 }
326 
327 #endif /* CONFIG_PPC_EARLY_DEBUG_USBGECKO */
328 
329