/****************************************************************************
 * arch/risc-v/src/common/riscv_createstack.c
 *
 *   Copyright (C) 2011, 2013, 2015 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <sys/types.h>
#include <stdint.h>
#include <sched.h>
#include <debug.h>

#include <nuttx/kmalloc.h>
#include <nuttx/arch.h>
#include <nuttx/tls.h>
#include <nuttx/board.h>
#include <arch/board/board.h>

#include "riscv_arch.h"
#include "riscv_internal.h"

/****************************************************************************
 * Pre-processor Macros
 ****************************************************************************/

/* RISC-V requires at least a 4-byte stack alignment.
 * For floating point use, however, the stack must be aligned to 8-byte
 * addresses.
 */

#if defined(CONFIG_LIBC_FLOATINGPOINT) || defined (CONFIG_ARCH_RV64GC)
#  define STACK_ALIGNMENT   8
#else
#  define STACK_ALIGNMENT   4
#endif

/* Stack alignment macros */

#define STACK_ALIGN_MASK    (STACK_ALIGNMENT-1)
#define STACK_ALIGN_DOWN(a) ((a) & ~STACK_ALIGN_MASK)
#define STACK_ALIGN_UP(a)   (((a) + STACK_ALIGN_MASK) & ~STACK_ALIGN_MASK)

/****************************************************************************
 * Private Types
 ****************************************************************************/

/****************************************************************************
 * Private Function Prototypes
 ****************************************************************************/

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: up_create_stack
 *
 * Description:
 *   Allocate a stack for a new thread and setup up stack-related information
 *   in the TCB.
 *
 *   The following TCB fields must be initialized by this function:
 *
 *   - adj_stack_size: Stack size after adjustment for hardware, processor,
 *     etc.  This value is retained only for debug purposes.
 *   - stack_alloc_ptr: Pointer to allocated stack
 *   - adj_stack_ptr: Adjusted stack_alloc_ptr for HW.  The initial value of
 *     the stack pointer.
 *
 * Input Parameters:
 *   - tcb: The TCB of new task
 *   - stack_size:  The requested stack size.  At least this much
 *     must be allocated.
 *   - ttype:  The thread type.  This may be one of following (defined in
 *     include/nuttx/sched.h):
 *
 *       TCB_FLAG_TTYPE_TASK     Normal user task
 *       TCB_FLAG_TTYPE_PTHREAD  User pthread
 *       TCB_FLAG_TTYPE_KERNEL   Kernel thread
 *
 *     This thread type is normally available in the flags field of the TCB,
 *     however, there are certain contexts where the TCB may not be fully
 *     initialized when up_create_stack is called.
 *
 *     If CONFIG_BUILD_KERNEL is defined, then this thread type may affect
 *     how the stack is allocated.  For example, kernel thread stacks should
 *     be allocated from protected kernel memory.  Stacks for user tasks and
 *     threads must come from memory that is accessible to user code.
 *
 ****************************************************************************/

int up_create_stack(FAR struct tcb_s *tcb, size_t stack_size, uint8_t ttype)
{
  /* Add the size of the TLS information structure */

  stack_size += sizeof(struct tls_info_s);

#ifdef CONFIG_TLS_ALIGNED
  /* The allocated stack size must not exceed the maximum possible for the
   * TLS feature.
   */

  DEBUGASSERT(stack_size <= TLS_MAXSTACK);
  if (stack_size >= TLS_MAXSTACK)
    {
      stack_size = TLS_MAXSTACK;
    }
#endif

  /* Is there already a stack allocated of a different size?  Because of
   * alignment issues, stack_size might erroneously appear to be of a
   * different size.  Fortunately, this is not a critical operation.
   */

  if (tcb->stack_alloc_ptr && tcb->adj_stack_size != stack_size)
    {
      /* Yes.. Release the old stack */

      up_release_stack(tcb, ttype);
    }

  /* Do we need to allocate a new stack? */

  if (!tcb->stack_alloc_ptr)
    {
      /* Allocate the stack.  If DEBUG is enabled (but not stack debug),
       * then create a zeroed stack to make stack dumps easier to trace.
       * If TLS is enabled, then we must allocate aligned stacks.
       */

#ifdef CONFIG_TLS_ALIGNED
#ifdef CONFIG_MM_KERNEL_HEAP
      /* Use the kernel allocator if this is a kernel thread */

      if (ttype == TCB_FLAG_TTYPE_KERNEL)
        {
          tcb->stack_alloc_ptr =
            (uint32_t *)kmm_memalign(TLS_STACK_ALIGN, stack_size);
        }
      else
#endif
        {
          /* Use the user-space allocator if this is a task or pthread */

          tcb->stack_alloc_ptr =
            (uint32_t *)kumm_memalign(TLS_STACK_ALIGN, stack_size);
        }

#else /* CONFIG_TLS_ALIGNED */
#ifdef CONFIG_MM_KERNEL_HEAP
      /* Use the kernel allocator if this is a kernel thread */

      if (ttype == TCB_FLAG_TTYPE_KERNEL)
        {
          tcb->stack_alloc_ptr = (uint32_t *)kmm_malloc(stack_size);
        }
      else
#endif
        {
          /* Use the user-space allocator if this is a task or pthread */

          tcb->stack_alloc_ptr = (uint32_t *)kumm_malloc(stack_size);
        }
#endif /* CONFIG_TLS_ALIGNED */

#ifdef CONFIG_DEBUG_FEATURES
      /* Was the allocation successful? */

      if (!tcb->stack_alloc_ptr)
        {
          serr("ERROR: Failed to allocate stack, size %zu\n", stack_size);
        }
#endif
    }

  /* Did we successfully allocate a stack? */

  if (tcb->stack_alloc_ptr)
    {
#if defined(CONFIG_STACK_COLORATION)
      uintptr_t stack_base;
#endif
      size_t top_of_stack;
      size_t size_of_stack;

      /* RISCV uses a push-down stack:  the stack grows toward lower
       * addresses in memory.  The stack pointer register points to the
       * lowest, valid working address (the "top" of the stack).  Items on
       * the stack are referenced as positive word offsets from sp.
       */

      top_of_stack = (uintptr_t)tcb->stack_alloc_ptr + stack_size - 4;

      /* The RISC-V stack must be aligned at word (4 byte) boundaries; for
       * floating point use, the stack must be aligned to 8-byte addresses.
       * If necessary top_of_stack must be rounded down to the next
       * boundary to meet these alignment requirements.
       */

      top_of_stack = STACK_ALIGN_DOWN(top_of_stack);
      size_of_stack = top_of_stack - (uintptr_t)tcb->stack_alloc_ptr + 4;

      /* Save the adjusted stack values in the struct tcb_s */

      tcb->adj_stack_ptr  = (FAR uint32_t *)top_of_stack;
      tcb->adj_stack_size = size_of_stack;

      /* Initialize the TLS data structure */

      memset(tcb->stack_alloc_ptr, 0, sizeof(struct tls_info_s));

#ifdef CONFIG_STACK_COLORATION
      /* If stack debug is enabled, then fill the stack with a
       * recognizable value that we can use later to test for high
       * water marks.
       */

      stack_base = (uintptr_t)tcb->stack_alloc_ptr +
                   sizeof(struct tls_info_s);
      stack_size = tcb->adj_stack_size -
                   sizeof(struct tls_info_s);
      up_stack_color((FAR void *)stack_base, stack_size);

#endif /* CONFIG_STACK_COLORATION */

      board_autoled_on(LED_STACKCREATED);
      return OK;
    }

  return ERROR;
}

/****************************************************************************
 * Name: up_stack_color
 *
 * Description:
 *   Write a well know value into the stack
 *
 ****************************************************************************/

#ifdef CONFIG_STACK_COLORATION
void up_stack_color(FAR void *stackbase, size_t nbytes)
{
  /* Take extra care that we do not write outsize the stack boundaries */

  uint32_t *stkptr = (uint32_t *)(((uintptr_t)stackbase + 3) & ~3);
  uintptr_t stkend = (((uintptr_t)stackbase + nbytes) & ~3);
  size_t    nwords = (stkend - (uintptr_t)stackbase) >> 2;

  /* Set the entire stack to the coloration value */

  while (nwords-- > 0)
    {
      *stkptr++ = STACK_COLOR;
    }
}
#endif
