tape_34xx.c

linux-2.6.15.6

/*
 *  drivers/s390/char/tape_34xx.c
 *    tape device discipline for 3480/3490 tapes.
 *
 *  S390 and zSeries version
 *    Copyright (C) 2001,2002 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *    Author(s): Carsten Otte <[e-mail]>
 *		 Tuan Ngo-Anh <[e-mail]>
 *		 Martin Schwidefsky <[e-mail]>
 */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/bio.h>
#include <linux/workqueue.h>

#define TAPE_DBF_AREA	tape_34xx_dbf

#include "tape.h"
#include "tape_std.h"

#define PRINTK_HEADER "TAPE_34XX: "

/*
 * Pointer to debug area.
 */
debug_info_t *TAPE_DBF_AREA = NULL;
EXPORT_SYMBOL(TAPE_DBF_AREA);

enum tape_34xx_type {
	tape_3480,
	tape_3490,
};

#define TAPE34XX_FMT_3480	0
#define TAPE34XX_FMT_3480_2_XF	1
#define TAPE34XX_FMT_3480_XF	2

struct tape_34xx_block_id {
	unsigned int	wrap		: 1;
	unsigned int	segment		: 7;
	unsigned int	format		: 2;
	unsigned int	block		: 22;
};

/*
 * A list of block ID's is used to faster seek blocks.
 */
struct tape_34xx_sbid {
	struct list_head		list;
	struct tape_34xx_block_id	bid;
};

static void tape_34xx_delete_sbid_from(struct tape_device *, int);

/*
 * Medium sense for 34xx tapes. There is no 'real' medium sense call.
 * So we just do a normal sense.
 */
static int
tape_34xx_medium_sense(struct tape_device *device)
{
	struct tape_request *request;
	unsigned char       *sense;
	int                  rc;

	request = tape_alloc_request(1, 32);
	if (IS_ERR(request)) {
		DBF_EXCEPTION(6, "MSEN fail\n");
		return PTR_ERR(request);
	}

	request->op = TO_MSEN;
	tape_ccw_end(request->cpaddr, SENSE, 32, request->cpdata);

	rc = tape_do_io_interruptible(device, request);
	if (request->rc == 0) {
		sense = request->cpdata;

		/*
		 * This isn't quite correct. But since INTERVENTION_REQUIRED
		 * means that the drive is 'neither ready nor on-line' it is
		 * only slightly inaccurate to say there is no tape loaded if
		 * the drive isn't online...
		 */
		if (sense[0] & SENSE_INTERVENTION_REQUIRED)
			tape_med_state_set(device, MS_UNLOADED);
		else
			tape_med_state_set(device, MS_LOADED);

		if (sense[1] & SENSE_WRITE_PROTECT)
			device->tape_generic_status |= GMT_WR_PROT(~0);
		else
			device->tape_generic_status &= ~GMT_WR_PROT(~0);
	} else {
		DBF_EVENT(4, "tape_34xx: medium sense failed with rc=%d\n",
			request->rc);
	}
	tape_free_request(request);

	return rc;
}

/*
 * These functions are currently used only to schedule a medium_sense for
 * later execution. This is because we get an interrupt whenever a medium
 * is inserted but cannot call tape_do_io* from an interrupt context.
 * Maybe that's useful for other actions we want to start from the
 * interrupt handler.
 */
static void
tape_34xx_work_handler(void *data)
{
	struct {
		struct tape_device	*device;
		enum tape_op		 op;
		struct work_struct	 work;
	} *p = data;

	switch(p->op) {
		case TO_MSEN:
			tape_34xx_medium_sense(p->device);
			break;
		default:
			DBF_EVENT(3, "T34XX: internal error: unknown work\n");
	}

	p->device = tape_put_device(p->device);
	kfree(p);
}

static int
tape_34xx_schedule_work(struct tape_device *device, enum tape_op op)
{
	struct {
		struct tape_device	*device;
		enum tape_op		 op;
		struct work_struct	 work;
	} *p;

	if ((p = kmalloc(sizeof(*p), GFP_ATOMIC)) == NULL)
		return -ENOMEM;

	memset(p, 0, sizeof(*p));
	INIT_WORK(&p->work, tape_34xx_work_handler, p);

	p->device = tape_get_device_reference(device);
	p->op     = op;

	schedule_work(&p->work);
	return 0;
}

/*
 * Done Handler is called when dev stat = DEVICE-END (successful operation)
 */
static inline int
tape_34xx_done(struct tape_request *request)
{
	DBF_EVENT(6, "%s done\n", tape_op_verbose[request->op]);

	switch (request->op) {
		case TO_DSE:
		case TO_RUN:
		case TO_WRI:
		case TO_WTM:
		case TO_ASSIGN:
		case TO_UNASSIGN:
			tape_34xx_delete_sbid_from(request->device, 0);
			break;
		default:
			;
	}
	return TAPE_IO_SUCCESS;
}

static inline int
tape_34xx_erp_failed(struct tape_request *request, int rc)
{
	DBF_EVENT(3, "Error recovery failed for %s (RC=%d)\n",
		  tape_op_verbose[request->op], rc);
	return rc;
}

static inline int
tape_34xx_erp_succeeded(struct tape_request *request)
{
	DBF_EVENT(3, "Error Recovery successful for %s\n",
		  tape_op_verbose[request->op]);
	return tape_34xx_done(request);
}

static inline int
tape_34xx_erp_retry(struct tape_request *request)
{
	DBF_EVENT(3, "xerp retr %s\n", tape_op_verbose[request->op]);
	return TAPE_IO_RETRY;
}

/*
 * This function is called, when no request is outstanding and we get an
 * interrupt
 */
static int
tape_34xx_unsolicited_irq(struct tape_device *device, struct irb *irb)
{
	if (irb->scsw.dstat == 0x85 /* READY */) {
		/* A medium was inserted in the drive. */
		DBF_EVENT(6, "xuud med\n");
		tape_34xx_delete_sbid_from(device, 0);
		tape_34xx_schedule_work(device, TO_MSEN);
	} else {
		DBF_EVENT(3, "unsol.irq! dev end: %08x\n", device->cdev_id);
		PRINT_WARN("Unsolicited IRQ (Device End) caught.\n");
		tape_dump_sense(device, NULL, irb);
	}
	return TAPE_IO_SUCCESS;
}

/*
 * Read Opposite Error Recovery Function:
 * Used, when Read Forward does not work
 */
static int
tape_34xx_erp_read_opposite(struct tape_device *device,
			    struct tape_request *request)
{
	if (request->op == TO_RFO) {
		/*
		 * We did read forward, but the data could not be read
		 * *correctly*. We transform the request to a read backward
		 * and try again.
		 */
		tape_std_read_backward(device, request);
		return tape_34xx_erp_retry(request);
	}
	if (request->op != TO_RBA)
		PRINT_ERR("read_opposite called with state:%s\n",
			  tape_op_verbose[request->op]);
	/*
	 * We tried to read forward and backward, but hat no
	 * success -> failed.
	 */
	return tape_34xx_erp_failed(request, -EIO);
}

static int
tape_34xx_erp_bug(struct tape_device *device, struct tape_request *request,
		  struct irb *irb, int no)
{
	if (request->op != TO_ASSIGN) {
		PRINT_WARN("An unexpected condition #%d was caught in "
			   "tape error recovery.\n", no);
		PRINT_WARN("Please report this incident.\n");
		if (request)
			PRINT_WARN("Operation of tape:%s\n",
				   tape_op_verbose[request->op]);
		tape_dump_sense(device, request, irb);
	}
	return tape_34xx_erp_failed(request, -EIO);
}

/*
 * Handle data overrun between cu and drive. The channel speed might
 * be too slow.
 */
static int
tape_34xx_erp_overrun(struct tape_device *device, struct tape_request *request,
		      struct irb *irb)
{
	if (irb->ecw[3] == 0x40) {
		PRINT_WARN ("Data overrun error between control-unit "
			    "and drive. Use a faster channel connection, "
			    "if possible! \n");
		return tape_34xx_erp_failed(request, -EIO);
	}
	return tape_34xx_erp_bug(device, request, irb, -1);
}

/*
 * Handle record sequence error.
 */
static int
tape_34xx_erp_sequence(struct tape_device *device,
		       struct tape_request *request, struct irb *irb)
{
	if (irb->ecw[3] == 0x41) {
		/*
		 * cu detected incorrect block-id sequence on tape.
		 */
		PRINT_WARN("Illegal block-id sequence found!\n");
		return tape_34xx_erp_failed(request, -EIO);
	}
	/*
	 * Record sequence error bit is set, but erpa does not
	 * show record sequence error.
	 */
	return tape_34xx_erp_bug(device, request, irb, -2);
}

/*
 * This function analyses the tape's sense-data in case of a unit-check.
 * If possible, it tries to recover from the error. Else the user is
 * informed about the problem.
 */
static int
tape_34xx_unit_check(struct tape_device *device, struct tape_request *request,
		     struct irb *irb)
{
	int inhibit_cu_recovery;
	__u8* sense;

	inhibit_cu_recovery = (*device->modeset_byte & 0x80) ? 1 : 0;
	sense = irb->ecw;

#ifdef CONFIG_S390_TAPE_BLOCK
	if (request->op == TO_BLOCK) {
		/*
		 * Recovery for block device requests. Set the block_position
		 * to something invalid and retry.
		 */
		device->blk_data.block_position = -1;
		if (request->retries-- <= 0)
			return tape_34xx_erp_failed(request, -EIO);
		else
			return tape_34xx_erp_retry(request);
	}
#endif

	if (
		sense[0] & SENSE_COMMAND_REJECT &&
		sense[1] & SENSE_WRITE_PROTECT
	) {
		if (
			request->op == TO_DSE ||
			request->op == TO_WRI ||
			request->op == TO_WTM
		) {
			/* medium is write protected */
			return tape_34xx_erp_failed(request, -EACCES);
		} else {
			return tape_34xx_erp_bug(device, request, irb, -3);
		}
	}

	/*
	 * Special cases for various tape-states when reaching
	 * end of recorded area
	 *
	 * FIXME: Maybe a special case of the special case:
	 *        sense[0] == SENSE_EQUIPMENT_CHECK &&
	 *        sense[1] == SENSE_DRIVE_ONLINE    &&
	 *        sense[3] == 0x47 (Volume Fenced)
	 *
	 *        This was caused by continued FSF or FSR after an
	 *        'End Of Data'.
	 */
	if ((
		sense[0] == SENSE_DATA_CHECK      ||
		sense[0] == SENSE_EQUIPMENT_CHECK ||
		sense[0] == SENSE_EQUIPMENT_CHECK + SENSE_DEFERRED_UNIT_CHECK
	) && (
		sense[1] == SENSE_DRIVE_ONLINE ||
		sense[1] == SENSE_BEGINNING_OF_TAPE + SENSE_WRITE_MODE
	)) {
		switch (request->op) {
		/*
		 * sense[0] == SENSE_DATA_CHECK   &&
		 * sense[1] == SENSE_DRIVE_ONLINE
		 * sense[3] == 0x36 (End Of Data)
		 *
		 * Further seeks might return a 'Volume Fenced'.
		 */
		case TO_FSF:
		case TO_FSB:
			/* Trying to seek beyond end of recorded area */
			return tape_34xx_erp_failed(request, -ENOSPC);
		case TO_BSB:
			return tape_34xx_erp_retry(request);

		/*
		 * sense[0] == SENSE_DATA_CHECK   &&
		 * sense[1] == SENSE_DRIVE_ONLINE &&
		 * sense[3] == 0x36 (End Of Data)
		 */
		case TO_LBL:
			/* Block could not be located. */
			tape_34xx_delete_sbid_from(device, 0);
			return tape_34xx_erp_failed(request, -EIO);

		case TO_RFO:
			/* Read beyond end of recorded area -> 0 bytes read */
			return tape_34xx_erp_failed(request, 0);

		/*
		 * sense[0] == SENSE_EQUIPMENT_CHECK &&
		 * sense[1] == SENSE_DRIVE_ONLINE    &&
		 * sense[3] == 0x38 (Physical End Of Volume)
		 */
		case TO_WRI:
			/* Writing at physical end of volume */
			return tape_34xx_erp_failed(request, -ENOSPC);
		default:
			PRINT_ERR("Invalid op in %s:%i\n",
				  __FUNCTION__, __LINE__);
			return tape_34xx_erp_failed(request, 0);
		}
	}

	/* Sensing special bits */
	if (sense[0] & SENSE_BUS_OUT_CHECK)
		return tape_34xx_erp_retry(request);

	if (sense[0] & SENSE_DATA_CHECK) {
		/*
		 * hardware failure, damaged tape or improper
		 * operating conditions
		 */
		switch (sense[3]) {
		case 0x23:
			/* a read data check occurred */
			if ((sense[2] & SENSE_TAPE_SYNC_MODE) ||
			    inhibit_cu_recovery)
				// data check is not permanent, may be
				// recovered. We always use async-mode with
				// cu-recovery, so this should *never* happen.
				return tape_34xx_erp_bug(device, request,
							 irb, -4);

			/* data check is permanent, CU recovery has failed */
			PRINT_WARN("Permanent read error\n");
			return tape_34xx_erp_failed(request, -EIO);
		case 0x25:
			// a write data check occurred
			if ((sense[2] & SENSE_TAPE_SYNC_MODE) ||
			    inhibit_cu_recovery)
				// data check is not permanent, may be
				// recovered. We always use async-mode with
				// cu-recovery, so this should *never* happen.
				return tape_34xx_erp_bug(device, request,
							 irb, -5);

			// data check is permanent, cu-recovery has failed
			PRINT_WARN("Permanent write error\n");
			return tape_34xx_erp_failed(request, -EIO);
		case 0x26:
			/* Data Check (read opposite) occurred. */
			return tape_34xx_erp_read_opposite(device, request);
		case 0x28:
			/* ID-Mark at tape start couldn't be written */
			PRINT_WARN("ID-Mark could not be written.\n");
			return tape_34xx_erp_failed(request, -EIO);
		case 0x31:
			/* Tape void. Tried to read beyond end of device. */
			PRINT_WARN("Read beyond end of recorded area.\n");
			return tape_34xx_erp_failed(request, -ENOSPC);
		case 0x41:
			/* Record sequence error. */
			PRINT_WARN("Invalid block-id sequence found.\n");
			return tape_34xx_erp_failed(request, -EIO);
		default: