// SPDX-License-Identifier: GPL-2.0-or-later

/*
 * IBM ASM Service Processor Device Driver
 *
 * Copyright (C) IBM Corporation, 2004
 *
 * Author: Max Asböck <amax@us.ibm.com>
 */

#include <linux/sched.h>
#include <linux/slab.h>
#include "ibmasm.h"
#include "lowlevel.h"

static void exec_next_command(struct service_processor *sp);

static atomic_t command_count = ATOMIC_INIT(0);

struct command *ibmasm_new_command(struct service_processor *sp, size_t buffer_size)
{
	struct command *cmd;

	if (buffer_size > IBMASM_CMD_MAX_BUFFER_SIZE)
		return NULL;

	cmd = kzalloc(sizeof(struct command), GFP_KERNEL);
	if (cmd == NULL)
		return NULL;


	cmd->buffer = kzalloc(buffer_size, GFP_KERNEL);
	if (cmd->buffer == NULL) {
		kfree(cmd);
		return NULL;
	}
	cmd->buffer_size = buffer_size;

	kref_init(&cmd->kref);
	cmd->lock = &sp->lock;

	cmd->status = IBMASM_CMD_PENDING;
	init_waitqueue_head(&cmd->wait);
	INIT_LIST_HEAD(&cmd->queue_node);

	atomic_inc(&command_count);
	dbg("command count: %d\n", atomic_read(&command_count));

	return cmd;
}

void ibmasm_free_command(struct kref *kref)
{
	struct command *cmd = to_command(kref);

	list_del(&cmd->queue_node);
	atomic_dec(&command_count);
	dbg("command count: %d\n", atomic_read(&command_count));
	kfree(cmd->buffer);
	kfree(cmd);
}

static void enqueue_command(struct service_processor *sp, struct command *cmd)
{
	list_add_tail(&cmd->queue_node, &sp->command_queue);
}

static struct command *dequeue_command(struct service_processor *sp)
{
	struct command *cmd;
	struct list_head *next;

	if (list_empty(&sp->command_queue))
		return NULL;

	next = sp->command_queue.next;
	list_del_init(next);
	cmd = list_entry(next, struct command, queue_node);

	return cmd;
}

static inline void do_exec_command(struct service_processor *sp)
{
	char tsbuf[32];

	dbg("%s:%d at %s\n", __func__, __LINE__, get_timestamp(tsbuf));

	if (ibmasm_send_i2o_message(sp)) {
		sp->current_command->status = IBMASM_CMD_FAILED;
		wake_up(&sp->current_command->wait);
		command_put(sp->current_command);
		exec_next_command(sp);
	}
}

/**
 * exec_command
 * send a command to a service processor
 * Commands are executed sequentially. One command (sp->current_command)
 * is sent to the service processor. Once the interrupt handler gets a
 * message of type command_response, the message is copied into
 * the current commands buffer,
 */
void ibmasm_exec_command(struct service_processor *sp, struct command *cmd)
{
	unsigned long flags;
	char tsbuf[32];

	dbg("%s:%d at %s\n", __func__, __LINE__, get_timestamp(tsbuf));

	spin_lock_irqsave(&sp->lock, flags);

	if (!sp->current_command) {
		sp->current_command = cmd;
		command_get(sp->current_command);
		spin_unlock_irqrestore(&sp->lock, flags);
		do_exec_command(sp);
	} else {
		enqueue_command(sp, cmd);
		spin_unlock_irqrestore(&sp->lock, flags);
	}
}

static void exec_next_command(struct service_processor *sp)
{
	unsigned long flags;
	char tsbuf[32];

	dbg("%s:%d at %s\n", __func__, __LINE__, get_timestamp(tsbuf));

	spin_lock_irqsave(&sp->lock, flags);
	sp->current_command = dequeue_command(sp);
	if (sp->current_command) {
		command_get(sp->current_command);
		spin_unlock_irqrestore(&sp->lock, flags);
		do_exec_command(sp);
	} else {
		spin_unlock_irqrestore(&sp->lock, flags);
	}
}

/**
 * Sleep until a command has failed or a response has been received
 * and the command status been updated by the interrupt handler.
 * (see receive_response).
 */
void ibmasm_wait_for_response(struct command *cmd, int timeout)
{
	wait_event_interruptible_timeout(cmd->wait,
				cmd->status == IBMASM_CMD_COMPLETE ||
				cmd->status == IBMASM_CMD_FAILED,
				timeout * HZ);
}

/**
 * receive_command_response
 * called by the interrupt handler when a dot command of type command_response
 * was received.
 */
void ibmasm_receive_command_response(struct service_processor *sp, void *response, size_t size)
{
	struct command *cmd = sp->current_command;

	if (!sp->current_command)
		return;

	memcpy_fromio(cmd->buffer, response, min(size, cmd->buffer_size));
	cmd->status = IBMASM_CMD_COMPLETE;
	wake_up(&sp->current_command->wait);
	command_put(sp->current_command);
	exec_next_command(sp);
}
