/****************************************************************************
 * arch/risc-v/src/common/riscv_percpu.h
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 ****************************************************************************/

#ifndef __ARCH_RISC_V_SRC_COMMON_RISCV_PERCPU_H
#define __ARCH_RISC_V_SRC_COMMON_RISCV_PERCPU_H

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

#include <nuttx/config.h>

#include <arch/irq.h>

#ifndef __ASSEMBLY__
#  include <stdint.h>
#  include <nuttx/arch.h>
#endif /* __ASSEMBLY__ */

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

/* Can be used by assembly code to access the structure, example:
 *
 * Get percpu structure:
 * 1: csrr    a0, CSR_SCRATCH
 *
 * Get hartid:
 * 2: REGLOAD a0, RISCV_PERCPU_HARTID(a0)
 */

#define RISCV_PERCPU_TCB        (0 * INT_REG_SIZE)
#define RISCV_PERCPU_HARTID     (1 * INT_REG_SIZE)
#define RISCV_PERCPU_IRQSTACK   (2 * INT_REG_SIZE)
#define RISCV_PERCPU_USP        (3 * INT_REG_SIZE)
#define RISCV_PERCPU_KSP        (4 * INT_REG_SIZE)

#ifndef __ASSEMBLY__

/****************************************************************************
 * Public Types
 ****************************************************************************/

/* Per CPU save area. Access to this structure can be gained via the scratch
 * ([m/s]scratch) register. Prior to this, every CPU that
 * wishes to access this information must call riscv_percpu_add_hart() which
 * will set up [m/s]scratch to point to the CPUs own area
 */

union riscv_percpu_s
{
  union riscv_percpu_s *next;      /* For sl list linkage */
  struct
  {
    struct tcb_s       *tcb;       /* Current thread TCB */
    uintreg_t           hartid;    /* Hart ID */
    uintreg_t           irq_stack; /* Interrupt stack */
    uintreg_t           usp;       /* Area to store user sp */
    uintreg_t           ksp;       /* Area to load kernel sp */
  };
};

typedef union riscv_percpu_s riscv_percpu_t;

/****************************************************************************
 * Public Function Prototypes
 ****************************************************************************/

/****************************************************************************
 * Name: riscv_percpu_add_hart
 *
 * Description:
 *   Get add a hart to the per CPU area
 *
 * Input Parameters:
 *   hartid - Hart number
 *
 ****************************************************************************/

void riscv_percpu_add_hart(uintptr_t hartid);

/****************************************************************************
 * Name: riscv_percpu_get_hartid
 *
 * Description:
 *   Get harts own hartid by reading it from the per CPU area. This is safe
 *   to use from lower privilege modes than M-mode.
 *
 * Returned Value:
 *   Hart id
 *
 ****************************************************************************/

uintptr_t riscv_percpu_get_hartid(void);

/****************************************************************************
 * Name: riscv_percpu_get_irqstack
 *
 * Description:
 *   Get harts own IRQ stack by reading it from the per CPU area.
 *
 * Returned Value:
 *   IRQ stack, or 0 if no IRQ stack is assigned
 *
 ****************************************************************************/

uintptr_t riscv_percpu_get_irqstack(void);

/****************************************************************************
 * Name: riscv_percpu_set_kstack
 *
 * Description:
 *   Set current kernel stack, so it can be taken quickly into use when a
 *   trap is taken.
 *
 * Input Parameters:
 *   ksp - Pointer to the kernel stack
 *
 * Returned Value:
 *   None
 *
 ****************************************************************************/

void riscv_percpu_set_kstack(uintptr_t ksp);

/****************************************************************************
 * Name: riscv_percpu_set_thread
 *
 * Description:
 *   Set current thread (tcb), so it can be found quickly when a trap is
 *   taken.
 *
 * Input Parameters:
 *   tcb - Pointer to the current thread's tcb
 *
 * Returned Value:
 *   None
 *
 ****************************************************************************/

void riscv_percpu_set_thread(struct tcb_s *tcb);

#endif /* __ASSEMBLY__ */
#endif /* __ARCH_RISC_V_SRC_COMMON_RISCV_PERCPU_H */