1 files changed, 620 insertions, 0 deletions

diff --git a/drivers/s390/block/scm_blk.c b/drivers/s390/block/scm_blk.c
new file mode 100644
index 000000000..75d9896de
--- /dev/null
+++ b/drivers/s390/block/scm_blk.c
@@ -0,0 +1,620 @@
+/*
+ * Block driver for s390 storage class memory.
+ *
+ * Copyright IBM Corp. 2012
+ * Author(s): Sebastian Ott <sebott@linux.vnet.ibm.com>
+ */
+
+#define KMSG_COMPONENT "scm_block"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#include <linux/interrupt.h>
+#include <linux/spinlock.h>
+#include <linux/mempool.h>
+#include <linux/module.h>
+#include <linux/blkdev.h>
+#include <linux/genhd.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <asm/eadm.h>
+#include "scm_blk.h"
+
+debug_info_t *scm_debug;
+static int scm_major;
+static mempool_t *aidaw_pool;
+static DEFINE_SPINLOCK(list_lock);
+static LIST_HEAD(inactive_requests);
+static unsigned int nr_requests = 64;
+static unsigned int nr_requests_per_io = 8;
+static atomic_t nr_devices = ATOMIC_INIT(0);
+module_param(nr_requests, uint, S_IRUGO);
+MODULE_PARM_DESC(nr_requests, "Number of parallel requests.");
+
+module_param(nr_requests_per_io, uint, S_IRUGO);
+MODULE_PARM_DESC(nr_requests_per_io, "Number of requests per IO.");
+
+MODULE_DESCRIPTION("Block driver for s390 storage class memory.");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("scm:scmdev*");
+
+static void __scm_free_rq(struct scm_request *scmrq)
+{
+	struct aob_rq_header *aobrq = to_aobrq(scmrq);
+
+	free_page((unsigned long) scmrq->aob);
+	__scm_free_rq_cluster(scmrq);
+	kfree(scmrq->request);
+	kfree(aobrq);
+}
+
+static void scm_free_rqs(void)
+{
+	struct list_head *iter, *safe;
+	struct scm_request *scmrq;
+
+	spin_lock_irq(&list_lock);
+	list_for_each_safe(iter, safe, &inactive_requests) {
+		scmrq = list_entry(iter, struct scm_request, list);
+		list_del(&scmrq->list);
+		__scm_free_rq(scmrq);
+	}
+	spin_unlock_irq(&list_lock);
+
+	mempool_destroy(aidaw_pool);
+}
+
+static int __scm_alloc_rq(void)
+{
+	struct aob_rq_header *aobrq;
+	struct scm_request *scmrq;
+
+	aobrq = kzalloc(sizeof(*aobrq) + sizeof(*scmrq), GFP_KERNEL);
+	if (!aobrq)
+		return -ENOMEM;
+
+	scmrq = (void *) aobrq->data;
+	scmrq->aob = (void *) get_zeroed_page(GFP_DMA);
+	if (!scmrq->aob)
+		goto free;
+
+	scmrq->request = kcalloc(nr_requests_per_io, sizeof(scmrq->request[0]),
+				 GFP_KERNEL);
+	if (!scmrq->request)
+		goto free;
+
+	if (__scm_alloc_rq_cluster(scmrq))
+		goto free;
+
+	INIT_LIST_HEAD(&scmrq->list);
+	spin_lock_irq(&list_lock);
+	list_add(&scmrq->list, &inactive_requests);
+	spin_unlock_irq(&list_lock);
+
+	return 0;
+free:
+	__scm_free_rq(scmrq);
+	return -ENOMEM;
+}
+
+static int scm_alloc_rqs(unsigned int nrqs)
+{
+	int ret = 0;
+
+	aidaw_pool = mempool_create_page_pool(max(nrqs/8, 1U), 0);
+	if (!aidaw_pool)
+		return -ENOMEM;
+
+	while (nrqs-- && !ret)
+		ret = __scm_alloc_rq();
+
+	return ret;
+}
+
+static struct scm_request *scm_request_fetch(void)
+{
+	struct scm_request *scmrq = NULL;
+
+	spin_lock(&list_lock);
+	if (list_empty(&inactive_requests))
+		goto out;
+	scmrq = list_first_entry(&inactive_requests, struct scm_request, list);
+	list_del(&scmrq->list);
+out:
+	spin_unlock(&list_lock);
+	return scmrq;
+}
+
+static void scm_request_done(struct scm_request *scmrq)
+{
+	unsigned long flags;
+	struct msb *msb;
+	u64 aidaw;
+	int i;
+
+	for (i = 0; i < nr_requests_per_io && scmrq->request[i]; i++) {
+		msb = &scmrq->aob->msb[i];
+		aidaw = msb->data_addr;
+
+		if ((msb->flags & MSB_FLAG_IDA) && aidaw &&
+		    IS_ALIGNED(aidaw, PAGE_SIZE))
+			mempool_free(virt_to_page(aidaw), aidaw_pool);
+	}
+
+	spin_lock_irqsave(&list_lock, flags);
+	list_add(&scmrq->list, &inactive_requests);
+	spin_unlock_irqrestore(&list_lock, flags);
+}
+
+static bool scm_permit_request(struct scm_blk_dev *bdev, struct request *req)
+{
+	return rq_data_dir(req) != WRITE || bdev->state != SCM_WR_PROHIBIT;
+}
+
+static inline struct aidaw *scm_aidaw_alloc(void)
+{
+	struct page *page = mempool_alloc(aidaw_pool, GFP_ATOMIC);
+
+	return page ? page_address(page) : NULL;
+}
+
+static inline unsigned long scm_aidaw_bytes(struct aidaw *aidaw)
+{
+	unsigned long _aidaw = (unsigned long) aidaw;
+	unsigned long bytes = ALIGN(_aidaw, PAGE_SIZE) - _aidaw;
+
+	return (bytes / sizeof(*aidaw)) * PAGE_SIZE;
+}
+
+struct aidaw *scm_aidaw_fetch(struct scm_request *scmrq, unsigned int bytes)
+{
+	struct aidaw *aidaw;
+
+	if (scm_aidaw_bytes(scmrq->next_aidaw) >= bytes)
+		return scmrq->next_aidaw;
+
+	aidaw = scm_aidaw_alloc();
+	if (aidaw)
+		memset(aidaw, 0, PAGE_SIZE);
+	return aidaw;
+}
+
+static int scm_request_prepare(struct scm_request *scmrq)
+{
+	struct scm_blk_dev *bdev = scmrq->bdev;
+	struct scm_device *scmdev = bdev->gendisk->private_data;
+	int pos = scmrq->aob->request.msb_count;
+	struct msb *msb = &scmrq->aob->msb[pos];
+	struct request *req = scmrq->request[pos];
+	struct req_iterator iter;
+	struct aidaw *aidaw;
+	struct bio_vec bv;
+
+	aidaw = scm_aidaw_fetch(scmrq, blk_rq_bytes(req));
+	if (!aidaw)
+		return -ENOMEM;
+
+	msb->bs = MSB_BS_4K;
+	scmrq->aob->request.msb_count++;
+	msb->scm_addr = scmdev->address + ((u64) blk_rq_pos(req) << 9);
+	msb->oc = (rq_data_dir(req) == READ) ? MSB_OC_READ : MSB_OC_WRITE;
+	msb->flags |= MSB_FLAG_IDA;
+	msb->data_addr = (u64) aidaw;
+
+	rq_for_each_segment(bv, req, iter) {
+		WARN_ON(bv.bv_offset);
+		msb->blk_count += bv.bv_len >> 12;
+		aidaw->data_addr = (u64) page_address(bv.bv_page);
+		aidaw++;
+	}
+
+	scmrq->next_aidaw = aidaw;
+	return 0;
+}
+
+static inline void scm_request_set(struct scm_request *scmrq,
+				   struct request *req)
+{
+	scmrq->request[scmrq->aob->request.msb_count] = req;
+}
+
+static inline void scm_request_init(struct scm_blk_dev *bdev,
+				    struct scm_request *scmrq)
+{
+	struct aob_rq_header *aobrq = to_aobrq(scmrq);
+	struct aob *aob = scmrq->aob;
+
+	memset(scmrq->request, 0,
+	       nr_requests_per_io * sizeof(scmrq->request[0]));
+	memset(aob, 0, sizeof(*aob));
+	aobrq->scmdev = bdev->scmdev;
+	aob->request.cmd_code = ARQB_CMD_MOVE;
+	aob->request.data = (u64) aobrq;
+	scmrq->bdev = bdev;
+	scmrq->retries = 4;
+	scmrq->error = 0;
+	/* We don't use all msbs - place aidaws at the end of the aob page. */
+	scmrq->next_aidaw = (void *) &aob->msb[nr_requests_per_io];
+	scm_request_cluster_init(scmrq);
+}
+
+static void scm_ensure_queue_restart(struct scm_blk_dev *bdev)
+{
+	if (atomic_read(&bdev->queued_reqs)) {
+		/* Queue restart is triggered by the next interrupt. */
+		return;
+	}
+	blk_delay_queue(bdev->rq, SCM_QUEUE_DELAY);
+}
+
+void scm_request_requeue(struct scm_request *scmrq)
+{
+	struct scm_blk_dev *bdev = scmrq->bdev;
+	int i;
+
+	scm_release_cluster(scmrq);
+	for (i = 0; i < nr_requests_per_io && scmrq->request[i]; i++)
+		blk_requeue_request(bdev->rq, scmrq->request[i]);
+
+	atomic_dec(&bdev->queued_reqs);
+	scm_request_done(scmrq);
+	scm_ensure_queue_restart(bdev);
+}
+
+void scm_request_finish(struct scm_request *scmrq)
+{
+	struct scm_blk_dev *bdev = scmrq->bdev;
+	int i;
+
+	scm_release_cluster(scmrq);
+	for (i = 0; i < nr_requests_per_io && scmrq->request[i]; i++)
+		blk_end_request_all(scmrq->request[i], scmrq->error);
+
+	atomic_dec(&bdev->queued_reqs);
+	scm_request_done(scmrq);
+}
+
+static int scm_request_start(struct scm_request *scmrq)
+{
+	struct scm_blk_dev *bdev = scmrq->bdev;
+	int ret;
+
+	atomic_inc(&bdev->queued_reqs);
+	if (!scmrq->aob->request.msb_count) {
+		scm_request_requeue(scmrq);
+		return -EINVAL;
+	}
+
+	ret = eadm_start_aob(scmrq->aob);
+	if (ret) {
+		SCM_LOG(5, "no subchannel");
+		scm_request_requeue(scmrq);
+	}
+	return ret;
+}
+
+static void scm_blk_request(struct request_queue *rq)
+{
+	struct scm_device *scmdev = rq->queuedata;
+	struct scm_blk_dev *bdev = dev_get_drvdata(&scmdev->dev);
+	struct scm_request *scmrq = NULL;
+	struct request *req;
+
+	while ((req = blk_peek_request(rq))) {
+		if (req->cmd_type != REQ_TYPE_FS) {
+			blk_start_request(req);
+			blk_dump_rq_flags(req, KMSG_COMPONENT " bad request");
+			blk_end_request_all(req, -EIO);
+			continue;
+		}
+
+		if (!scm_permit_request(bdev, req))
+			goto out;
+
+		if (!scmrq) {
+			scmrq = scm_request_fetch();
+			if (!scmrq) {
+				SCM_LOG(5, "no request");
+				goto out;
+			}
+			scm_request_init(bdev, scmrq);
+		}
+		scm_request_set(scmrq, req);
+
+		if (!scm_reserve_cluster(scmrq)) {
+			SCM_LOG(5, "cluster busy");
+			scm_request_set(scmrq, NULL);
+			if (scmrq->aob->request.msb_count)
+				goto out;
+
+			scm_request_done(scmrq);
+			return;
+		}
+
+		if (scm_need_cluster_request(scmrq)) {
+			if (scmrq->aob->request.msb_count) {
+				/* Start cluster requests separately. */
+				scm_request_set(scmrq, NULL);
+				if (scm_request_start(scmrq))
+					return;
+			} else {
+				atomic_inc(&bdev->queued_reqs);
+				blk_start_request(req);
+				scm_initiate_cluster_request(scmrq);
+			}
+			scmrq = NULL;
+			continue;
+		}
+
+		if (scm_request_prepare(scmrq)) {
+			SCM_LOG(5, "aidaw alloc failed");
+			scm_request_set(scmrq, NULL);
+			goto out;
+		}
+		blk_start_request(req);
+
+		if (scmrq->aob->request.msb_count < nr_requests_per_io)
+			continue;
+
+		if (scm_request_start(scmrq))
+			return;
+
+		scmrq = NULL;
+	}
+out:
+	if (scmrq)
+		scm_request_start(scmrq);
+	else
+		scm_ensure_queue_restart(bdev);
+}
+
+static void __scmrq_log_error(struct scm_request *scmrq)
+{
+	struct aob *aob = scmrq->aob;
+
+	if (scmrq->error == -ETIMEDOUT)
+		SCM_LOG(1, "Request timeout");
+	else {
+		SCM_LOG(1, "Request error");
+		SCM_LOG_HEX(1, &aob->response, sizeof(aob->response));
+	}
+	if (scmrq->retries)
+		SCM_LOG(1, "Retry request");
+	else
+		pr_err("An I/O operation to SCM failed with rc=%d\n",
+		       scmrq->error);
+}
+
+void scm_blk_irq(struct scm_device *scmdev, void *data, int error)
+{
+	struct scm_request *scmrq = data;
+	struct scm_blk_dev *bdev = scmrq->bdev;
+
+	scmrq->error = error;
+	if (error)
+		__scmrq_log_error(scmrq);
+
+	spin_lock(&bdev->lock);
+	list_add_tail(&scmrq->list, &bdev->finished_requests);
+	spin_unlock(&bdev->lock);
+	tasklet_hi_schedule(&bdev->tasklet);
+}
+
+static void scm_blk_handle_error(struct scm_request *scmrq)
+{
+	struct scm_blk_dev *bdev = scmrq->bdev;
+	unsigned long flags;
+
+	if (scmrq->error != -EIO)
+		goto restart;
+
+	/* For -EIO the response block is valid. */
+	switch (scmrq->aob->response.eqc) {
+	case EQC_WR_PROHIBIT:
+		spin_lock_irqsave(&bdev->lock, flags);
+		if (bdev->state != SCM_WR_PROHIBIT)
+			pr_info("%lx: Write access to the SCM increment is suspended\n",
+				(unsigned long) bdev->scmdev->address);
+		bdev->state = SCM_WR_PROHIBIT;
+		spin_unlock_irqrestore(&bdev->lock, flags);
+		goto requeue;
+	default:
+		break;
+	}
+
+restart:
+	if (!eadm_start_aob(scmrq->aob))
+		return;
+
+requeue:
+	spin_lock_irqsave(&bdev->rq_lock, flags);
+	scm_request_requeue(scmrq);
+	spin_unlock_irqrestore(&bdev->rq_lock, flags);
+}
+
+static void scm_blk_tasklet(struct scm_blk_dev *bdev)
+{
+	struct scm_request *scmrq;
+	unsigned long flags;
+
+	spin_lock_irqsave(&bdev->lock, flags);
+	while (!list_empty(&bdev->finished_requests)) {
+		scmrq = list_first_entry(&bdev->finished_requests,
+					 struct scm_request, list);
+		list_del(&scmrq->list);
+		spin_unlock_irqrestore(&bdev->lock, flags);
+
+		if (scmrq->error && scmrq->retries-- > 0) {
+			scm_blk_handle_error(scmrq);
+
+			/* Request restarted or requeued, handle next. */
+			spin_lock_irqsave(&bdev->lock, flags);
+			continue;
+		}
+
+		if (scm_test_cluster_request(scmrq)) {
+			scm_cluster_request_irq(scmrq);
+			spin_lock_irqsave(&bdev->lock, flags);
+			continue;
+		}
+
+		scm_request_finish(scmrq);
+		spin_lock_irqsave(&bdev->lock, flags);
+	}
+	spin_unlock_irqrestore(&bdev->lock, flags);
+	/* Look out for more requests. */
+	blk_run_queue(bdev->rq);
+}
+
+static const struct block_device_operations scm_blk_devops = {
+	.owner = THIS_MODULE,
+};
+
+int scm_blk_dev_setup(struct scm_blk_dev *bdev, struct scm_device *scmdev)
+{
+	struct request_queue *rq;
+	int len, ret = -ENOMEM;
+	unsigned int devindex, nr_max_blk;
+
+	devindex = atomic_inc_return(&nr_devices) - 1;
+	/* scma..scmz + scmaa..scmzz */
+	if (devindex > 701) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	bdev->scmdev = scmdev;
+	bdev->state = SCM_OPER;
+	spin_lock_init(&bdev->rq_lock);
+	spin_lock_init(&bdev->lock);
+	INIT_LIST_HEAD(&bdev->finished_requests);
+	atomic_set(&bdev->queued_reqs, 0);
+	tasklet_init(&bdev->tasklet,
+		     (void (*)(unsigned long)) scm_blk_tasklet,
+		     (unsigned long) bdev);
+
+	rq = blk_init_queue(scm_blk_request, &bdev->rq_lock);
+	if (!rq)
+		goto out;
+
+	bdev->rq = rq;
+	nr_max_blk = min(scmdev->nr_max_block,
+			 (unsigned int) (PAGE_SIZE / sizeof(struct aidaw)));
+
+	blk_queue_logical_block_size(rq, 1 << 12);
+	blk_queue_max_hw_sectors(rq, nr_max_blk << 3); /* 8 * 512 = blk_size */
+	blk_queue_max_segments(rq, nr_max_blk);
+	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, rq);
+	queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, rq);
+	scm_blk_dev_cluster_setup(bdev);
+
+	bdev->gendisk = alloc_disk(SCM_NR_PARTS);
+	if (!bdev->gendisk)
+		goto out_queue;
+
+	rq->queuedata = scmdev;
+	bdev->gendisk->driverfs_dev = &scmdev->dev;
+	bdev->gendisk->private_data = scmdev;
+	bdev->gendisk->fops = &scm_blk_devops;
+	bdev->gendisk->queue = rq;
+	bdev->gendisk->major = scm_major;
+	bdev->gendisk->first_minor = devindex * SCM_NR_PARTS;
+
+	len = snprintf(bdev->gendisk->disk_name, DISK_NAME_LEN, "scm");
+	if (devindex > 25) {
+		len += snprintf(bdev->gendisk->disk_name + len,
+				DISK_NAME_LEN - len, "%c",
+				'a' + (devindex / 26) - 1);
+		devindex = devindex % 26;
+	}
+	snprintf(bdev->gendisk->disk_name + len, DISK_NAME_LEN - len, "%c",
+		 'a' + devindex);
+
+	/* 512 byte sectors */
+	set_capacity(bdev->gendisk, scmdev->size >> 9);
+	add_disk(bdev->gendisk);
+	return 0;
+
+out_queue:
+	blk_cleanup_queue(rq);
+out:
+	atomic_dec(&nr_devices);
+	return ret;
+}
+
+void scm_blk_dev_cleanup(struct scm_blk_dev *bdev)
+{
+	tasklet_kill(&bdev->tasklet);
+	del_gendisk(bdev->gendisk);
+	blk_cleanup_queue(bdev->gendisk->queue);
+	put_disk(bdev->gendisk);
+}
+
+void scm_blk_set_available(struct scm_blk_dev *bdev)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&bdev->lock, flags);
+	if (bdev->state == SCM_WR_PROHIBIT)
+		pr_info("%lx: Write access to the SCM increment is restored\n",
+			(unsigned long) bdev->scmdev->address);
+	bdev->state = SCM_OPER;
+	spin_unlock_irqrestore(&bdev->lock, flags);
+}
+
+static bool __init scm_blk_params_valid(void)
+{
+	if (!nr_requests_per_io || nr_requests_per_io > 64)
+		return false;
+
+	return scm_cluster_size_valid();
+}
+
+static int __init scm_blk_init(void)
+{
+	int ret = -EINVAL;
+
+	if (!scm_blk_params_valid())
+		goto out;
+
+	ret = register_blkdev(0, "scm");
+	if (ret < 0)
+		goto out;
+
+	scm_major = ret;
+	ret = scm_alloc_rqs(nr_requests);
+	if (ret)
+		goto out_free;
+
+	scm_debug = debug_register("scm_log", 16, 1, 16);
+	if (!scm_debug) {
+		ret = -ENOMEM;
+		goto out_free;
+	}
+
+	debug_register_view(scm_debug, &debug_hex_ascii_view);
+	debug_set_level(scm_debug, 2);
+
+	ret = scm_drv_init();
+	if (ret)
+		goto out_dbf;
+
+	return ret;
+
+out_dbf:
+	debug_unregister(scm_debug);
+out_free:
+	scm_free_rqs();
+	unregister_blkdev(scm_major, "scm");
+out:
+	return ret;
+}
+module_init(scm_blk_init);
+
+static void __exit scm_blk_cleanup(void)
+{
+	scm_drv_cleanup();
+	debug_unregister(scm_debug);
+	scm_free_rqs();
+	unregister_blkdev(scm_major, "scm");
+}
+module_exit(scm_blk_cleanup);