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  * Retrieves and prepares the virtual address needed to access the hardware.
197  */
198 static void __iomem *__init ug_udbg_setup_exi_io_base(struct device_node *np)
199 {
200 	void __iomem *exi_io_base = NULL;
201 	phys_addr_t paddr;
202 	const unsigned int *reg;
203 
204 	reg = of_get_property(np, "reg", NULL);
205 	if (reg) {
206 		paddr = of_translate_address(np, reg);
207 		if (paddr)
208 			exi_io_base = ioremap(paddr, reg[1]);
209 	}
210 	return exi_io_base;
211 }
212 
213 /*
214  * Checks if a USB Gecko adapter is inserted in any memory card slot.
215  */
216 static void __iomem *__init ug_udbg_probe(void __iomem *exi_io_base)
217 {
218 	int i;
219 
220 	/* look for a usbgecko on memcard slots A and B */
221 	for (i = 0; i < 2; i++) {
222 		ug_io_base = exi_io_base + 0x14 * i;
223 		if (ug_is_adapter_present())
224 			break;
225 	}
226 	if (i == 2)
227 		ug_io_base = NULL;
228 	return ug_io_base;
229 
230 }
231 
232 /*
233  * USB Gecko udbg support initialization.
234  */
235 void __init ug_udbg_init(void)
236 {
237 	struct device_node *np;
238 	void __iomem *exi_io_base;
239 
240 	if (ug_io_base)
241 		udbg_printf("%s: early -> final\n", __func__);
242 
243 	np = of_find_compatible_node(NULL, NULL, "nintendo,flipper-exi");
244 	if (!np) {
245 		udbg_printf("%s: EXI node not found\n", __func__);
246 		goto out;
247 	}
248 
249 	exi_io_base = ug_udbg_setup_exi_io_base(np);
250 	if (!exi_io_base) {
251 		udbg_printf("%s: failed to setup EXI io base\n", __func__);
252 		goto done;
253 	}
254 
255 	if (!ug_udbg_probe(exi_io_base)) {
256 		udbg_printf("usbgecko_udbg: not found\n");
257 		iounmap(exi_io_base);
258 	} else {
259 		udbg_putc = ug_udbg_putc;
260 		udbg_getc = ug_udbg_getc;
261 		udbg_getc_poll = ug_udbg_getc_poll;
262 		udbg_printf("usbgecko_udbg: ready\n");
263 	}
264 
265 done:
266 	of_node_put(np);
267 out:
268 	return;
269 }
270 
271 #ifdef CONFIG_PPC_EARLY_DEBUG_USBGECKO
272 
273 static phys_addr_t __init ug_early_grab_io_addr(void)
274 {
275 #if defined(CONFIG_GAMECUBE)
276 	return 0x0c000000;
277 #elif defined(CONFIG_WII)
278 	return 0x0d000000;
279 #else
280 #error Invalid platform for USB Gecko based early debugging.
281 #endif
282 }
283 
284 /*
285  * USB Gecko early debug support initialization for udbg.
286  */
287 void __init udbg_init_usbgecko(void)
288 {
289 	void __iomem *early_debug_area;
290 	void __iomem *exi_io_base;
291 
292 	/*
293 	 * At this point we have a BAT already setup that enables I/O
294 	 * to the EXI hardware.
295 	 *
296 	 * The BAT uses a virtual address range reserved at the fixmap.
297 	 * This must match the virtual address configured in
298 	 * head_32.S:setup_usbgecko_bat().
299 	 */
300 	early_debug_area = (void __iomem *)__fix_to_virt(FIX_EARLY_DEBUG_BASE);
301 	exi_io_base = early_debug_area + 0x00006800;
302 
303 	/* try to detect a USB Gecko */
304 	if (!ug_udbg_probe(exi_io_base))
305 		return;
306 
307 	/* we found a USB Gecko, load udbg hooks */
308 	udbg_putc = ug_udbg_putc;
309 	udbg_getc = ug_udbg_getc;
310 	udbg_getc_poll = ug_udbg_getc_poll;
311 
312 	/*
313 	 * Prepare again the same BAT for MMU_init.
314 	 * This allows udbg I/O to continue working after the MMU is
315 	 * turned on for real.
316 	 * It is safe to continue using the same virtual address as it is
317 	 * a reserved fixmap area.
318 	 */
319 	setbat(1, (unsigned long)early_debug_area,
320 	       ug_early_grab_io_addr(), 128*1024, PAGE_KERNEL_NCG);
321 }
322 
323 #endif /* CONFIG_PPC_EARLY_DEBUG_USBGECKO */
324 
325