/arch/powerpc/platforms/embedded6xx/usbgecko_udbg.c

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