target/linux/ixp4xx/patches-2.6.25/190-cambria_support.patch

   1 Index: linux-2.6.25.4/arch/arm/mach-ixp4xx/Kconfig
   2 ===================================================================
   3 --- linux-2.6.25.4.orig/arch/arm/mach-ixp4xx/Kconfig
   4 +++ linux-2.6.25.4/arch/arm/mach-ixp4xx/Kconfig
   5 @@ -25,6 +25,14 @@ config MACH_AVILA
   6           Avila Network Platform. For more information on this platform,
   7           see <file:Documentation/arm/IXP4xx>.
   8
   9 +config MACH_CAMBRIA
  10 +       bool "Cambria"
  11 +       select PCI
  12 +       help
  13 +         Say 'Y' here if you want your kernel to support the Gateworks
  14 +         Cambria series. For more information on this platform,
  15 +         see <file:Documentation/arm/IXP4xx>.
  16 +
  17  config MACH_LOFT
  18      bool "Loft"
  19      depends on MACH_AVILA
  20 @@ -200,7 +208,7 @@ config CPU_IXP46X
  21
  22  config CPU_IXP43X
  23         bool
  24 -       depends on MACH_KIXRP435
  25 +       depends on MACH_KIXRP435 || MACH_CAMBRIA
  26         default y
  27
  28  config MACH_GTWX5715
  29 Index: linux-2.6.25.4/arch/arm/mach-ixp4xx/Makefile
  30 ===================================================================
  31 --- linux-2.6.25.4.orig/arch/arm/mach-ixp4xx/Makefile
  32 +++ linux-2.6.25.4/arch/arm/mach-ixp4xx/Makefile
  33 @@ -7,6 +7,7 @@ obj-pci-n       :=
  34
  35  obj-pci-$(CONFIG_ARCH_IXDP4XX)         += ixdp425-pci.o
  36  obj-pci-$(CONFIG_MACH_AVILA)           += avila-pci.o
  37 +obj-pci-$(CONFIG_MACH_CAMBRIA)         += cambria-pci.o
  38  obj-pci-$(CONFIG_MACH_IXDPG425)                += ixdpg425-pci.o
  39  obj-pci-$(CONFIG_ARCH_ADI_COYOTE)      += coyote-pci.o
  40  obj-pci-$(CONFIG_MACH_GTWX5715)                += gtwx5715-pci.o
  41 @@ -28,6 +29,7 @@ obj-y += common.o
  42
  43  obj-$(CONFIG_ARCH_IXDP4XX)     += ixdp425-setup.o
  44  obj-$(CONFIG_MACH_AVILA)       += avila-setup.o
  45 +obj-$(CONFIG_MACH_CAMBRIA)     += cambria-setup.o
  46  obj-$(CONFIG_MACH_IXDPG425)    += coyote-setup.o
  47  obj-$(CONFIG_ARCH_ADI_COYOTE)  += coyote-setup.o
  48  obj-$(CONFIG_MACH_GTWX5715)    += gtwx5715-setup.o
  49 Index: linux-2.6.25.4/arch/arm/mach-ixp4xx/cambria-pci.c
  50 ===================================================================
  51 --- /dev/null
  52 +++ linux-2.6.25.4/arch/arm/mach-ixp4xx/cambria-pci.c
  53 @@ -0,0 +1,74 @@
  54 +/*
  55 + * arch/arch/mach-ixp4xx/cambria-pci.c
  56 + *
  57 + * PCI setup routines for Gateworks Cambria series
  58 + *
  59 + * Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org>
  60 + *
  61 + * based on coyote-pci.c:
  62 + *     Copyright (C) 2002 Jungo Software Technologies.
  63 + *     Copyright (C) 2003 MontaVista Softwrae, Inc.
  64 + *
  65 + * Maintainer: Imre Kaloz <kaloz@openwrt.org>
  66 + *
  67 + * This program is free software; you can redistribute it and/or modify
  68 + * it under the terms of the GNU General Public License version 2 as
  69 + * published by the Free Software Foundation.
  70 + *
  71 + */
  72 +
  73 +#include <linux/kernel.h>
  74 +#include <linux/pci.h>
  75 +#include <linux/init.h>
  76 +#include <linux/irq.h>
  77 +
  78 +#include <asm/mach-types.h>
  79 +#include <asm/hardware.h>
  80 +#include <asm/irq.h>
  81 +
  82 +#include <asm/mach/pci.h>
  83 +
  84 +extern void ixp4xx_pci_preinit(void);
  85 +extern int ixp4xx_setup(int nr, struct pci_sys_data *sys);
  86 +extern struct pci_bus *ixp4xx_scan_bus(int nr, struct pci_sys_data *sys);
  87 +
  88 +void __init cambria_pci_preinit(void)
  89 +{
  90 +       set_irq_type(IRQ_IXP4XX_GPIO11, IRQT_LOW);
  91 +       set_irq_type(IRQ_IXP4XX_GPIO10, IRQT_LOW);
  92 +       set_irq_type(IRQ_IXP4XX_GPIO9, IRQT_LOW);
  93 +       set_irq_type(IRQ_IXP4XX_GPIO8, IRQT_LOW);
  94 +
  95 +       ixp4xx_pci_preinit();
  96 +}
  97 +
  98 +static int __init cambria_map_irq(struct pci_dev *dev, u8 slot, u8 pin)
  99 +{
 100 +       if (slot == 1)
 101 +               return IRQ_IXP4XX_GPIO11;
 102 +       else if (slot == 2)
 103 +               return IRQ_IXP4XX_GPIO10;
 104 +       else if (slot == 3)
 105 +               return IRQ_IXP4XX_GPIO9;
 106 +       else if (slot == 4)
 107 +               return IRQ_IXP4XX_GPIO8;
 108 +       else return -1;
 109 +}
 110 +
 111 +struct hw_pci cambria_pci __initdata = {
 112 +       .nr_controllers = 1,
 113 +       .preinit =        cambria_pci_preinit,
 114 +       .swizzle =        pci_std_swizzle,
 115 +       .setup =          ixp4xx_setup,
 116 +       .scan =           ixp4xx_scan_bus,
 117 +       .map_irq =        cambria_map_irq,
 118 +};
 119 +
 120 +int __init cambria_pci_init(void)
 121 +{
 122 +       if (machine_is_cambria())
 123 +               pci_common_init(&cambria_pci);
 124 +       return 0;
 125 +}
 126 +
 127 +subsys_initcall(cambria_pci_init);
 128 Index: linux-2.6.25.4/arch/arm/mach-ixp4xx/cambria-setup.c
 129 ===================================================================
 130 --- /dev/null
 131 +++ linux-2.6.25.4/arch/arm/mach-ixp4xx/cambria-setup.c
 132 @@ -0,0 +1,445 @@
 133 +/*
 134 + * arch/arm/mach-ixp4xx/cambria-setup.c
 135 + *
 136 + * Board setup for the Gateworks Cambria series
 137 + *
 138 + * Copyright (C) 2008 Imre Kaloz <Kaloz@openwrt.org>
 139 + *
 140 + * based on coyote-setup.c:
 141 + *      Copyright (C) 2003-2005 MontaVista Software, Inc.
 142 + *
 143 + * Author: Imre Kaloz <Kaloz@openwrt.org>
 144 + */
 145 +
 146 +#include <linux/kernel.h>
 147 +#include <linux/init.h>
 148 +#include <linux/device.h>
 149 +#include <linux/if_ether.h>
 150 +#include <linux/socket.h>
 151 +#include <linux/netdevice.h>
 152 +#include <linux/serial.h>
 153 +#include <linux/tty.h>
 154 +#include <linux/serial_8250.h>
 155 +#include <linux/slab.h>
 156 +#ifdef CONFIG_SENSORS_EEPROM
 157 +# include <linux/i2c.h>
 158 +# include <linux/eeprom.h>
 159 +#endif
 160 +
 161 +#include <linux/leds.h>
 162 +#include <linux/i2c-gpio.h>
 163 +#include <asm/types.h>
 164 +#include <asm/setup.h>
 165 +#include <asm/memory.h>
 166 +#include <asm/hardware.h>
 167 +#include <asm/irq.h>
 168 +#include <asm/mach-types.h>
 169 +#include <asm/mach/arch.h>
 170 +#include <asm/mach/flash.h>
 171 +
 172 +struct cambria_board_info {
 173 +  unsigned char *model;
 174 +  void    (* setup)(void);
 175 +};
 176 +
 177 +static struct cambria_board_info *cambria_info __initdata;
 178 +
 179 +static struct flash_platform_data cambria_flash_data = {
 180 +       .map_name       = "cfi_probe",
 181 +       .width          = 2,
 182 +};
 183 +
 184 +static struct resource cambria_flash_resource = {
 185 +       .flags          = IORESOURCE_MEM,
 186 +};
 187 +
 188 +static struct platform_device cambria_flash = {
 189 +       .name           = "IXP4XX-Flash",
 190 +       .id             = 0,
 191 +       .dev            = {
 192 +               .platform_data = &cambria_flash_data,
 193 +       },
 194 +       .num_resources  = 1,
 195 +       .resource       = &cambria_flash_resource,
 196 +};
 197 +
 198 +static struct i2c_gpio_platform_data cambria_i2c_gpio_data = {
 199 +       .sda_pin        = 7,
 200 +       .scl_pin        = 6,
 201 +};
 202 +
 203 +static struct platform_device cambria_i2c_gpio = {
 204 +       .name           = "i2c-gpio",
 205 +       .id             = 0,
 206 +       .dev            = {
 207 +               .platform_data  = &cambria_i2c_gpio_data,
 208 +       },
 209 +};
 210 +
 211 +static struct resource cambria_uart_resource = {
 212 +       .start  = IXP4XX_UART1_BASE_PHYS,
 213 +       .end    = IXP4XX_UART1_BASE_PHYS + 0x0fff,
 214 +       .flags  = IORESOURCE_MEM,
 215 +};
 216 +
 217 +static struct plat_serial8250_port cambria_uart_data[] = {
 218 +       {
 219 +               .mapbase        = IXP4XX_UART1_BASE_PHYS,
 220 +               .membase        = (char *)IXP4XX_UART1_BASE_VIRT + REG_OFFSET,
 221 +               .irq            = IRQ_IXP4XX_UART1,
 222 +               .flags          = UPF_BOOT_AUTOCONF | UPF_SKIP_TEST,
 223 +               .iotype         = UPIO_MEM,
 224 +               .regshift       = 2,
 225 +               .uartclk        = IXP4XX_UART_XTAL,
 226 +       },
 227 +       { },
 228 +};
 229 +
 230 +static struct platform_device cambria_uart = {
 231 +       .name           = "serial8250",
 232 +       .id             = PLAT8250_DEV_PLATFORM,
 233 +       .dev                    = {
 234 +               .platform_data  = cambria_uart_data,
 235 +       },
 236 +       .num_resources  = 1,
 237 +       .resource       = &cambria_uart_resource,
 238 +};
 239 +
 240 +static struct resource cambria_pata_resources[] = {
 241 +       {
 242 +               .flags  = IORESOURCE_MEM
 243 +       },
 244 +       {
 245 +               .flags  = IORESOURCE_MEM,
 246 +       },
 247 +       {
 248 +               .name   = "intrq",
 249 +               .start  = IRQ_IXP4XX_GPIO12,
 250 +               .end    = IRQ_IXP4XX_GPIO12,
 251 +               .flags  = IORESOURCE_IRQ,
 252 +       },
 253 +};
 254 +
 255 +static struct ixp4xx_pata_data cambria_pata_data = {
 256 +       .cs0_bits       = 0xbfff3c03,
 257 +       .cs1_bits       = 0xbfff3c03,
 258 +};
 259 +
 260 +static struct platform_device cambria_pata = {
 261 +       .name                   = "pata_ixp4xx_cf",
 262 +       .id                     = 0,
 263 +       .dev.platform_data      = &cambria_pata_data,
 264 +       .num_resources          = ARRAY_SIZE(cambria_pata_resources),
 265 +       .resource               = cambria_pata_resources,
 266 +};
 267 +
 268 +static struct eth_plat_info cambria_npec_data = {
 269 +       .phy    = 2,
 270 +       .rxq    = 4,
 271 +       .txreadyq       = 21,
 272 +};
 273 +
 274 +static struct eth_plat_info cambria_npea_data = {
 275 +       .phy    = 1,
 276 +       .rxq    = 2,
 277 +       .txreadyq       = 19,
 278 +};
 279 +
 280 +static struct platform_device cambria_npec_device = {
 281 +       .name           = "ixp4xx_eth",
 282 +       .id                     = IXP4XX_ETH_NPEC,
 283 +       .dev.platform_data      = &cambria_npec_data,
 284 +};
 285 +
 286 +static struct platform_device cambria_npea_device = {
 287 +       .name           = "ixp4xx_eth",
 288 +       .id                     = IXP4XX_ETH_NPEA,
 289 +       .dev.platform_data      = &cambria_npea_data,
 290 +};
 291 +
 292 +static struct gpio_led cambria_gpio_leds[] = {
 293 +  {
 294 +    .name   = "user",  /* green led */
 295 +    .gpio   = 5,
 296 +    .active_low = 1,
 297 +  }
 298 +};
 299 +
 300 +static struct gpio_led_platform_data cambria_gpio_leds_data = {
 301 +  .num_leds   = 1,
 302 +  .leds     = cambria_gpio_leds,
 303 +};
 304 +
 305 +static struct platform_device cambria_gpio_leds_device = {
 306 +  .name     = "leds-gpio",
 307 +  .id     = -1,
 308 +  .dev.platform_data  = &cambria_gpio_leds_data,
 309 +};
 310 +
 311 +
 312 +static struct latch_led cambria_latch_leds[] = {
 313 +       {
 314 +               .name   = "ledA",  /* green led */
 315 +               .bit    = 0,
 316 +       },
 317 +       {
 318 +               .name   = "ledB",  /* green led */
 319 +               .bit    = 1,
 320 +       },
 321 +       {
 322 +               .name   = "ledC",  /* green led */
 323 +               .bit    = 2,
 324 +       },
 325 +       {
 326 +               .name   = "ledD",  /* green led */
 327 +               .bit    = 3,
 328 +       },
 329 +       {
 330 +               .name   = "ledE",  /* green led */
 331 +               .bit    = 4,
 332 +       },
 333 +       {
 334 +               .name   = "ledF",  /* green led */
 335 +               .bit    = 5,
 336 +       },
 337 +       {
 338 +               .name   = "ledG",  /* green led */
 339 +               .bit    = 6,
 340 +       },
 341 +       {
 342 +               .name   = "ledH",  /* green led */
 343 +               .bit    = 7,
 344 +       }
 345 +};
 346 +
 347 +static struct latch_led_platform_data cambria_latch_leds_data = {
 348 +       .num_leds   = 8,
 349 +       .leds       = cambria_latch_leds,
 350 +       .mem        = 0x53F40000,
 351 +};
 352 +
 353 +static struct platform_device cambria_latch_leds_device = {
 354 +       .name     = "leds-latch",
 355 +       .id     = -1,
 356 +       .dev.platform_data  = &cambria_latch_leds_data,
 357 +};
 358 +
 359 +static struct resource cambria_usb0_resources[] = {
 360 +       {
 361 +               .start    = 0xCD000000,
 362 +               .end      = 0xCD000300,
 363 +               .flags    = IORESOURCE_MEM,
 364 +       },
 365 +       {
 366 +               .start    = 32,
 367 +               .flags    = IORESOURCE_IRQ,
 368 +       },
 369 +};
 370 +
 371 +static struct resource cambria_usb1_resources[] = {
 372 +       {
 373 +               .start    = 0xCE000000,
 374 +               .end      = 0xCE000300,
 375 +               .flags    = IORESOURCE_MEM,
 376 +       },
 377 +       {
 378 +               .start    = 33,
 379 +               .flags    = IORESOURCE_IRQ,
 380 +       },
 381 +};
 382 +
 383 +static u64 ehci_dma_mask = ~(u32)0;
 384 +
 385 +static struct platform_device cambria_usb0_device =  {
 386 +       .name   = "ixp4xx-ehci",
 387 +       .id   = 0,
 388 +       .dev = {
 389 +               .dma_mask               = &ehci_dma_mask,
 390 +               .coherent_dma_mask      = 0xffffffff,
 391 +       },
 392 +       .resource = cambria_usb0_resources,
 393 +       .num_resources  = 2,
 394 +};
 395 +
 396 +static struct platform_device cambria_usb1_device =  {
 397 +       .name   = "ixp4xx-ehci",
 398 +       .id   = 1,
 399 +       .dev = {
 400 +               .dma_mask               = &ehci_dma_mask,
 401 +               .coherent_dma_mask      = 0xffffffff,
 402 +       },
 403 +       .resource = cambria_usb1_resources,
 404 +       .num_resources  = 2,
 405 +};
 406 +
 407 +
 408 +static struct platform_device *cambria_devices[] __initdata = {
 409 +       &cambria_i2c_gpio,
 410 +       &cambria_flash,
 411 +       &cambria_uart,
 412 +};
 413 +
 414 +static void __init cambria_gw23xx_setup(void)
 415 +{
 416 +  platform_device_register(&cambria_npec_device);
 417 +  platform_device_register(&cambria_npea_device);
 418 +}
 419 +
 420 +#ifdef CONFIG_SENSORS_EEPROM
 421 +static void __init cambria_gw2350_setup(void)
 422 +{
 423 +  platform_device_register(&cambria_npec_device);
 424 +  platform_device_register(&cambria_npea_device);
 425 +
 426 +       platform_device_register(&cambria_usb0_device);
 427 +       platform_device_register(&cambria_usb1_device);
 428 +
 429 +       platform_device_register(&cambria_gpio_leds_device);
 430 +}
 431 +
 432 +static void __init cambria_gw2358_setup(void)
 433 +{
 434 +  platform_device_register(&cambria_npec_device);
 435 +  platform_device_register(&cambria_npea_device);
 436 +
 437 +       platform_device_register(&cambria_usb0_device);
 438 +       platform_device_register(&cambria_usb1_device);
 439 +
 440 +       platform_device_register(&cambria_pata);
 441 +
 442 +       platform_device_register(&cambria_latch_leds_device);
 443 +}
 444 +
 445 +static struct cambria_board_info cambria_boards[] __initdata = {
 446 +  {
 447 +    .model    = "GW2350",
 448 +    .setup    = cambria_gw2350_setup,
 449 +  }, {
 450 +    .model    = "GW2358",
 451 +    .setup    = cambria_gw2358_setup,
 452 +  }
 453 +};
 454 +
 455 +static struct cambria_board_info * __init cambria_find_board_info(char *model)
 456 +{
 457 +  int i;
 458 +
 459 +  for (i = 0; i < ARRAY_SIZE(cambria_boards); i++) {
 460 +    struct cambria_board_info *info = &cambria_boards[i];
 461 +    if (strncmp(info->model, model, strlen(info->model)) == 0)
 462 +      return info;
 463 +  }
 464 +
 465 +  return NULL;
 466 +}
 467 +
 468 +struct cambria_eeprom_header {
 469 +       unsigned char mac0[ETH_ALEN];
 470 +       unsigned char mac1[ETH_ALEN];
 471 +       unsigned char res0[4];
 472 +       unsigned char magic[2];
 473 +       unsigned char config[14];
 474 +       unsigned char model[16];
 475 +};
 476 +
 477 +static int __init cambria_eeprom_notify(struct notifier_block *self,
 478 +               unsigned long event, void *t)
 479 +{
 480 +  struct eeprom_data *ee = t;
 481 +  struct cambria_eeprom_header hdr;
 482 +
 483 +  if (cambria_info)
 484 +    return NOTIFY_DONE;
 485 +
 486 +  /* The eeprom is at address 0x51 */
 487 +  if (event != EEPROM_REGISTER || ee->client.addr != 0x51)
 488 +    return NOTIFY_DONE;
 489 +
 490 +  ee->attr->read(&ee->client.dev.kobj, ee->attr, (char *)&hdr,
 491 +              0, sizeof(hdr));
 492 +
 493 +  if (hdr.magic[0] != 'G' || hdr.magic[1] != 'W')
 494 +    return NOTIFY_DONE;
 495 +
 496 +  memcpy(&cambria_npec_data.hwaddr, hdr.mac0, ETH_ALEN);
 497 +  memcpy(&cambria_npea_data.hwaddr, hdr.mac1, ETH_ALEN);
 498 +
 499 +  cambria_info = cambria_find_board_info(hdr.model);
 500 +
 501 +  return NOTIFY_OK;
 502 +}
 503 +
 504 +static struct notifier_block cambria_eeprom_notifier __initdata = {
 505 +       .notifier_call = cambria_eeprom_notify
 506 +};
 507 +
 508 +static void __init cambria_register_eeprom_notifier(void)
 509 +{
 510 +  register_eeprom_notifier(&cambria_eeprom_notifier);
 511 +}
 512 +
 513 +static void __init cambria_unregister_eeprom_notifier(void)
 514 +{
 515 +  unregister_eeprom_notifier(&cambria_eeprom_notifier);
 516 +}
 517 +#else /* CONFIG_SENSORS_EEPROM */
 518 +static inline void cambria_register_eeprom_notifier(void) {};
 519 +static inline void cambria_unregister_eeprom_notifier(void) {};
 520 +#endif /* CONFIG_SENSORS_EEPROM */
 521 +
 522 +static void __init cambria_init(void)
 523 +{
 524 +       ixp4xx_sys_init();
 525 +
 526 +       cambria_flash_resource.start = IXP4XX_EXP_BUS_BASE(0);
 527 +       cambria_flash_resource.end = IXP4XX_EXP_BUS_BASE(0) + SZ_32M - 1;
 528 +
 529 +       *IXP4XX_EXP_CS0 |= IXP4XX_FLASH_WRITABLE;
 530 +       *IXP4XX_EXP_CS1 = *IXP4XX_EXP_CS0;
 531 +
 532 +       platform_add_devices(cambria_devices, ARRAY_SIZE(cambria_devices));
 533 +
 534 +       cambria_pata_resources[0].start = 0x53e00000;
 535 +       cambria_pata_resources[0].end = 0x53e3ffff;
 536 +
 537 +       cambria_pata_resources[1].start = 0x53e40000;
 538 +       cambria_pata_resources[1].end = 0x53e7ffff;
 539 +
 540 +       cambria_pata_data.cs0_cfg = IXP4XX_EXP_CS3;
 541 +       cambria_pata_data.cs1_cfg = IXP4XX_EXP_CS3;
 542 +
 543 +       cambria_register_eeprom_notifier();
 544 +}
 545 +
 546 +static int __init cambria_model_setup(void)
 547 +{
 548 +  if (!machine_is_cambria())
 549 +    return 0;
 550 +
 551 +  if (cambria_info) {
 552 +    printk(KERN_DEBUG "Running on Gateworks Cambria %s\n",
 553 +              cambria_info->model);
 554 +    cambria_info->setup();
 555 +  } else {
 556 +    printk(KERN_INFO "Unknown/missing Cambria model number"
 557 +            " -- defaults will be used\n");
 558 +    cambria_gw23xx_setup();
 559 +  }
 560 +
 561 +  cambria_unregister_eeprom_notifier();
 562 +  return 0;
 563 +}
 564 +late_initcall(cambria_model_setup);
 565 +
 566 +#ifdef CONFIG_MACH_CAMBRIA
 567 +MACHINE_START(CAMBRIA, "Gateworks Cambria series")
 568 +       /* Maintainer: Imre Kaloz <kaloz@openwrt.org> */
 569 +       .phys_io        = IXP4XX_PERIPHERAL_BASE_PHYS,
 570 +       .io_pg_offst    = ((IXP4XX_PERIPHERAL_BASE_VIRT) >> 18) & 0xfffc,
 571 +       .map_io         = ixp4xx_map_io,
 572 +       .init_irq       = ixp4xx_init_irq,
 573 +       .timer          = &ixp4xx_timer,
 574 +       .boot_params    = 0x0100,
 575 +       .init_machine   = cambria_init,
 576 +MACHINE_END
 577 +#endif
 578 Index: linux-2.6.25.4/include/asm-arm/arch-ixp4xx/hardware.h
 579 ===================================================================
 580 --- linux-2.6.25.4.orig/include/asm-arm/arch-ixp4xx/hardware.h
 581 +++ linux-2.6.25.4/include/asm-arm/arch-ixp4xx/hardware.h
 582 @@ -18,7 +18,7 @@
 583  #define __ASM_ARCH_HARDWARE_H__
 584
 585  #define PCIBIOS_MIN_IO         0x00001000
 586 -#define PCIBIOS_MIN_MEM                (cpu_is_ixp43x() ? 0x40000000 : 0x48000000)
 587 +#define PCIBIOS_MIN_MEM                (cpu_is_ixp43x() ? 0x48000000 : 0x48000000)
 588
 589  /*
 590   * We override the standard dma-mask routines for bouncing.