Board support package for the Atmel SAM V71/V70/E70/S70 chip platform.

The BSP is customized to a particular board/chip variant by means of configure
command line options.

Use --enable-chip=XYZ to select the chip variant where XYZ is one of same70j19,
same70j20, same70j21, same70n19, same70n20, same70n21, same70q19, same70q20,
same70q21, sams70j19, sams70j20, sams70j21, sams70n19, sams70n20, sams70n21,
sams70q19, sams70q20, sams70q21, samv71j19, samv71j20, samv71j21, samv71n19,
samv71n20, samv71n21, samv71q19, samv71q20 and samv71q21.  By default the BSP
uses the ATSAMV71Q21 chip.  Not all variants are tested.

Use --enable-sdram=XYZ to select the SDRAM variant where XYZ is one of
is42s16100e-7bli and is42s16320f-7bl. Not all variants are tested with all
controller and speed combinations.

Use BOARD_MAINOSC=XYZ to set the main oscillator frequency in Hz (default
12MHz).

Use ATSAM_MCK=XYZ to set the MCK frequency that should be used. The default case
(123000000) enables operation of an external SDRAM on the SAMv71 Explained
evaluation kit. Some other configurations (e.g. 150MHz) would be too fast on
that board.

Your application can also overwrite the clock settings.  If you have a
bootloader with one setting in your internal flash and an application with
another setting in your external SDRAM, you should also use the
ATSAM_CHANGE_CLOCK_FROM_SRAM=1 option. To overwrite the clock settings, define
the following structures in your application:

--------
const struct atsam_clock_config atsam_clock_config = {
  .pllar_init = my_custom_pllar_value,
  .mckr_init = my_custom_mckr_value,
  .mck_freq = my_resulting_mck_frequency
};

const struct BOARD_Sdram_Config BOARD_Sdram_Config = {
  .sdramc_tr = my_custom_sdramc_tr_value,
  .sdramc_cr = my_custom_sdramc_cr_value,
  .sdramc_mdr = my_custom_sdramc_mdr_value,
  .sdramc_cfr1 = my_custom_sdramc_cfr1_value
};
--------

Use ATSAM_SLOWCLOCK_USE_XTAL=0 to disable the usage of the external 32kHz
oscillator for the slow clock. This is useful for example for the SAM E70
Xplained kit.

Use ATSAM_CONSOLE_BAUD=XYZ to set the initial baud for console devices (default
115200).

Use ATSAM_CONSOLE_DEVICE_TYPE=XYZ to set the device type for /dev/console, use
0 for USART and 1 for UART (default USART).

Use ATSAM_CONSOLE_DEVICE_INDEX=XYZ to set the device index for /dev/console
(default 1, e.g. USART1).

Use ATSAM_CONSOLE_USE_INTERRUPTS=XYZ to set the use interrupt driven mode for
console devices (used by default).

Use ATSAM_MEMORY_TCM_SIZE=XYZ to set the size of tightly coupled memories (TCM)
in bytes (default 0x00000000).

Use ATSAM_MEMORY_INTFLASH_SIZE=XYZ to set the size of internal flash in bytes
(default is derived from chip variant).

Use ATSAM_MEMORY_INTSRAM_SIZE=XYZ to set the size of internal SRAM in bytes
(default is derived from chip variant).

Use ATSAM_MEMORY_SDRAM_SIZE=XYZ to set the size of external SDRAM in bytes
(default 0x00200000).

Use ATSAM_MEMORY_QSPIFLASH_SIZE=XYZ to set the size of QSPI flash in bytes
(default 0x00200000).

The pins may be configured by the application at link-time.  See
<bsp/pin-config.h>.

The clock driver uses the ARMv7-M Systick.

The console driver supports the USART and UART devices.

The default linker command file places the code into the internal flash.  Use
"LDFLAGS += -qnolinkcmds -T linkcmds.sdram" to place the code into the external
SDRAM.  Use "LDFLAGS += -qnolinkcmds -T linkcmds.intsram" to place the code
into the internal SRAM.

The fast text section uses the ITCM.  The fast data section uses the DTCM.

Data and instruction cache are enabled during system start.  The RTEMS cache
manager is supported with exception of the freeze functions.
