/*
 *  scst_cdrom.c
 *
 *  Copyright (C) 2004 - 2018 Vladislav Bolkhovitin <vst@vlnb.net>
 *  Copyright (C) 2004 - 2005 Leonid Stoljar
 *  Copyright (C) 2007 - 2018 Western Digital Corporation
 *
 *  SCSI CDROM (type 5) dev handler
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation, version 2
 *  of the License.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 *  GNU General Public License for more details.
 */

#include <linux/cdrom.h>
#include <scsi/scsi_host.h>
#include <linux/slab.h>
#include <asm/unaligned.h>

#define LOG_PREFIX	"dev_cdrom"

#ifdef INSIDE_KERNEL_TREE
#include <scst/scst.h>
#else
#include "scst.h"
#endif
#include "scst_dev_handler.h"

#define CDROM_NAME	"dev_cdrom"

#define CDROM_DEF_BLOCK_SHIFT	11

static int cdrom_attach(struct scst_device *);
static void cdrom_detach(struct scst_device *);
static int cdrom_parse(struct scst_cmd *);
static int cdrom_done(struct scst_cmd *);

static struct scst_dev_type cdrom_devtype = {
	.name =			CDROM_NAME,
	.type =			TYPE_ROM,
	.threads_num =		1,
	.parse_atomic =		1,
	.dev_done_atomic =	1,
	.attach =		cdrom_attach,
	.detach =		cdrom_detach,
	.parse =		cdrom_parse,
	.dev_done =		cdrom_done,
#if defined(CONFIG_SCST_DEBUG) || defined(CONFIG_SCST_TRACING)
	.default_trace_flags =	SCST_DEFAULT_DEV_LOG_FLAGS,
	.trace_flags =		&trace_flag,
#endif
};

static int cdrom_attach(struct scst_device *dev)
{
	int res, rc;
	uint8_t cmd[10];
	const int buffer_size = 512;
	uint8_t *buffer = NULL;
	int retries;
	unsigned char sense_buffer[SCSI_SENSE_BUFFERSIZE];
	enum dma_data_direction data_dir;

	TRACE_ENTRY();

	if (dev->scsi_dev == NULL ||
	    dev->scsi_dev->type != dev->type) {
		PRINT_ERROR("%s", "SCSI device not define or illegal type");
		res = -ENODEV;
		goto out;
	}

	buffer = kmalloc(buffer_size, GFP_KERNEL);
	if (!buffer) {
		PRINT_ERROR("Buffer memory allocation (size %d) failure",
			buffer_size);
		res = -ENOMEM;
		goto out;
	}

	/* Clear any existing UA's and get cdrom capacity (cdrom block size) */
	memset(cmd, 0, sizeof(cmd));
	cmd[0] = READ_CAPACITY;
	cmd[1] = (dev->scsi_dev->scsi_level <= SCSI_2) ?
	    ((dev->scsi_dev->lun << 5) & 0xe0) : 0;
	retries = SCST_DEV_RETRIES_ON_UA;
	while (1) {
		memset(buffer, 0, buffer_size);
		memset(sense_buffer, 0, sizeof(sense_buffer));
		data_dir = SCST_DATA_READ;

		TRACE_DBG("%s", "Doing READ_CAPACITY");
		rc = scst_scsi_execute(dev->scsi_dev, cmd, data_dir, buffer,
				       buffer_size, sense_buffer,
				       SCST_GENERIC_CDROM_REG_TIMEOUT, 3, 0);

		TRACE_DBG("READ_CAPACITY done: %x", rc);

		if ((rc == 0) ||
		    !scst_analyze_sense(sense_buffer,
				sizeof(sense_buffer), SCST_SENSE_KEY_VALID,
				UNIT_ATTENTION, 0, 0))
			break;

		if (!--retries) {
			PRINT_ERROR("UA not cleared after %d retries",
				SCST_DEV_RETRIES_ON_UA);
			dev->block_shift = CDROM_DEF_BLOCK_SHIFT;
			res = -ENODEV;
			goto out_free_buf;
		}
	}

	if (rc == 0) {
		uint32_t sector_size = get_unaligned_be32(&buffer[4]);

		if (sector_size == 0)
			dev->block_shift = CDROM_DEF_BLOCK_SHIFT;
		else
			dev->block_shift = scst_calc_block_shift(sector_size);
		TRACE_DBG("Sector size is %i scsi_level %d(SCSI_2 %d)",
			sector_size, dev->scsi_dev->scsi_level, SCSI_2);
		if (dev->block_shift < 9) {
			PRINT_ERROR("READ CAPACITY reported an invalid sector size: %d",
				    sector_size);
			res = -EINVAL;
			goto out_free_buf;
		}
	} else {
		dev->block_shift = CDROM_DEF_BLOCK_SHIFT;
		TRACE(TRACE_MINOR, "Read capacity failed: %x, using default "
			"sector size %d", rc, dev->block_shift);
		PRINT_BUFF_FLAG(TRACE_MINOR, "Returned sense", sense_buffer,
			sizeof(sense_buffer));
	}
	dev->block_size = 1 << dev->block_shift;

	res = scst_obtain_device_parameters(dev, NULL);
	if (res != 0) {
		PRINT_ERROR("Failed to obtain control parameters for device "
			"%s", dev->virt_name);
		goto out_free_buf;
	}

out_free_buf:
	kfree(buffer);

out:
	TRACE_EXIT();
	return res;
}

static void cdrom_detach(struct scst_device *dev)
{
	/* Nothing to do */
	return;
}

static int cdrom_parse(struct scst_cmd *cmd)
{
	int res = SCST_CMD_STATE_DEFAULT, rc;

	rc = scst_cdrom_generic_parse(cmd);
	if (rc != 0) {
		res = scst_get_cmd_abnormal_done_state(cmd);
		goto out;
	}

	cmd->retries = SCST_PASSTHROUGH_RETRIES;
out:
	return res;
}

static void cdrom_set_block_shift(struct scst_cmd *cmd, int block_shift)
{
	struct scst_device *dev = cmd->dev;
	int new_block_shift;

	/*
	 * No need for locks here, since *_detach() can not be
	 * called, when there are existing commands.
	 */
	new_block_shift = block_shift ? : CDROM_DEF_BLOCK_SHIFT;
	if (dev->block_shift != new_block_shift) {
		PRINT_INFO("%s: Changed block shift from %d into %d / %d",
			   dev->virt_name, dev->block_shift, block_shift,
			   new_block_shift);
		dev->block_shift = new_block_shift;
		dev->block_size = 1 << dev->block_shift;
	}
	return;
}

static int cdrom_done(struct scst_cmd *cmd)
{
	int res = SCST_CMD_STATE_DEFAULT;

	TRACE_ENTRY();

	res = scst_block_generic_dev_done(cmd, cdrom_set_block_shift);

	TRACE_EXIT_RES(res);
	return res;
}

static int __init cdrom_init(void)
{
	int res = 0;

	TRACE_ENTRY();

	cdrom_devtype.module = THIS_MODULE;

	res = scst_register_dev_driver(&cdrom_devtype);
	if (res < 0)
		goto out;


out:
	TRACE_EXIT();
	return res;

}

static void __exit cdrom_exit(void)
{
	TRACE_ENTRY();
	scst_unregister_dev_driver(&cdrom_devtype);
	TRACE_EXIT();
	return;
}

module_init(cdrom_init);
module_exit(cdrom_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Vladislav Bolkhovitin & Leonid Stoljar");
MODULE_DESCRIPTION("SCSI CDROM (type 5) dev handler for SCST");
MODULE_VERSION(SCST_VERSION_STRING);