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
41static void __iomem *ug_io_base;
42
43/*
44 * Performs one input/output transaction between the exi host and the usbgecko.
45 */
46static 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 */
78static 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 */
89static 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 */
98static 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 */
107static 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 */
126static 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 */
135static 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 */
148static 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 */
168static 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 */
176static 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 */
188static 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 */
198static 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 */
217void __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
247done:
248	of_node_put(np);
249out:
250	return;
251}
252
253#ifdef CONFIG_PPC_EARLY_DEBUG_USBGECKO
254
255static 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 */
269void __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