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
  40 static void __iomem *ug_io_base;
  41
  42 /*
  43  * Performs one input/output transaction between the exi host and the usbgecko.
  44  */
  45 static 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  */
  77 static 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  */
  88 static 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  */
  97 static 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  */
 106 static 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  */
 125 static 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  */
 134 static 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  */
 147 static 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  */
 167 static 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  */
 175 static 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  */
 187 static 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  */
 197 static 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  */
 215 static 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  */
 234 void __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
 264 done:
 265         of_node_put(np);
 266 out:
 267         return;
 268 }
 269
 270 #ifdef CONFIG_PPC_EARLY_DEBUG_USBGECKO
 271
 272 static 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  */
 286 void __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