#include "uart.h"
#include "psr.h"
#include "memory.h"
#include "translation_table_descriptors.h"
#include "ramfs.h"

void demo_paging_support(void)
{
  uint32_t ID_MMFR0;
  // get contents of coprocessor register to check for paging support
  asm("mrc p15, 0, %0, c0, c1, 4" : "=r" (ID_MMFR0));
  
  char *paging;
  
  switch(ID_MMFR0 & 0xf) /* lowest 4 bits indicate VMSA support */
    {
    case 0 : paging = "no paging\n\r"; break;
    case 1 : paging = "implementation defined paging\n\r"; break;
    case 2 : paging = "VMSAv6, with cache and TLB type registers\n\r"; break;
    case 3 : paging = "VMSAv7, with support for remapping and access flag\n\r"; break;
    case 4 : paging = "VMSAv7 with PXN bit supported\n\r"; break;
    case 5 : paging = "VMSAv7, PXN and long format descriptors. EPAE is supported.\n\r"; break;
    default : paging = "?_? unknown paging ?_?\n\r";
    }
  
  uart_puts(paging);
}

void demo_current_mode(void)
{

  // get content of current program status register to check the current
  // processor mode (should be system, as we set it in boot.S)
  PSR_t CPSR = read_CPSR();

  char *mode_name;
  
  switch(CPSR.fields.PSR_MODE_4_0)
    {
    case MODE_USER       : mode_name = "User (PL0)\r\n"; break;
    case MODE_FIQ        : mode_name = "FIQ (PL1)\r\n"; break;
    case MODE_IRQ        : mode_name = "IRQ (PL1)\r\n"; break;
    case MODE_SUPERVISOR : mode_name = "Supervisor (PL1)\r\n"; break;
    case MODE_MONITOR    : mode_name = "Monitor (PL1)\r\n"; break;
    case MODE_ABORT      : mode_name = "Abort (PL1)\r\n"; break;
    case MODE_HYPERVISOR : mode_name = "Hyp (PL2)\r\n"; break;
    case MODE_UNDEFINED  : mode_name = "Undefined (PL1)\r\n"; break;
    case MODE_SYSTEM     : mode_name = "System (PL1)\r\n"; break;
    default : mode_name = "Unknown mode\r\n"; break;
    }

  uart_puts("current mode: ");
  uart_puts(mode_name);
}

#define TRANSLATION_TABLE						\
  ((short_section_descriptor_t volatile*) TRANSLATION_TABLE_BASE)

extern char
  _binary_ramfs_img_start,
  _binary_ramfs_img_end,
  _binary_ramfs_img_size;

void demo_setup_PL0(void)
{
  // find PL_0_test.img im ramfs
  struct ramfile PL_0_test_img;

  if (find_file(&_binary_ramfs_img_start, "PL_0_test.img",
		&PL_0_test_img))
    {
      uart_puts("PL_0_test.img not found :(\r\n");
      asm volatile ("wfi");
    }

  short_section_descriptor_t volatile *PL0_section_entry =
    &TRANSLATION_TABLE[PL0_SECTION_NUMBER];
  short_section_descriptor_t volatile *UART_memory_section_entry =
    &TRANSLATION_TABLE[((uint32_t) GPIO_BASE) >> 20];

  short_section_descriptor_t
    PL0_section = *PL0_section_entry,
    UART_memory_section = *UART_memory_section_entry;

  // set up address of PL0 section
  PL0_section.SECTION_BASE_ADDRESS_31_20 =
    UNPRIVILEGED_MEMORY_START >> 20;

  // make the selected section and uart section available for PL0
  PL0_section.ACCESS_PERMISSIONS_2 =
    AP_2_0_MODEL_RW_ALL >> 2;
  PL0_section.ACCESS_PERMISSIONS_1_0 =
    AP_2_0_MODEL_RW_ALL & 0b011;

  UART_memory_section.ACCESS_PERMISSIONS_2 =
    AP_2_0_MODEL_RW_ALL >> 2;
  UART_memory_section.ACCESS_PERMISSIONS_1_0 =
    AP_2_0_MODEL_RW_ALL & 0b011;

  *PL0_section_entry = PL0_section;
  *UART_memory_section_entry = UART_memory_section;

  // invalidate main Translation Lookup Buffer (just in case)
  asm("mcr p15, 0, %0, c8, c7, 0\n\r"
      "isb" :: "r" (0) : "memory");
  
  // check that translation works... by copying a string using one
  // mapping and reading it using other :D
  char message[] = "mapped sections for PL0 code\n\r";
  
  unsigned int i;
  for (i = 0; i < sizeof(message); i++)
    ((volatile char*) UNPRIVILEGED_MEMORY_START)[i] = message[i];
  
  uart_puts((char*) VIRTUAL_PL0_MEMORY_START);

  // now paste a userspace program to that section
  for (uint32_t i = 0; i < PL_0_test_img.file_size; i++)
    ((volatile char*) VIRTUAL_PL0_MEMORY_START)[i] =
      PL_0_test_img.file_contents[i];

  uart_puts("copied PL0 code to it's section\n\r");
}

// needed for array initialization in demo_go_unprivileged()
void *memset(void *s, int c, size_t n)
{
  char *mem = s;
  
  for (size_t i = 0; i < n; i++)
    mem[i] = c;
  
  return s;
}

void demo_go_unprivileged(void)
{
  uint32_t PL0_regs[16] = {0};
  PL0_regs[15] = VIRTUAL_PL0_MEMORY_START;       // the new pc
  PL0_regs[13] = (PL0_SECTION_NUMBER + 1) << 20; // the new sp

  PSR_t new_SPSR = read_CPSR();
  new_SPSR.fields.PSR_MODE_4_0 = MODE_USER;
  write_SPSR(new_SPSR);

  uart_puts("All ready, jumping to PL0 code\n\r");
  
  asm volatile("ldm %0, {r0 - r15} ^" ::
	       "r" (PL0_regs));
}

extern char
  __interrupts_start,
  __interrupts_end,
  __interrupts_size;

extern void (*volatile system_reentry_point)(void);

void system_reentry(void)
{
  uart_puts("re-entered system");
  while(1);
}

void demo_setup_interrupts(void)
{
  system_reentry_point = system_reentry;

  for (size_t i = 0; i < (size_t) &__interrupts_size; i++)
    ((volatile char*) 0)[i] =
      (&__interrupts_start)[i];
}