s390: add scm block driver
Block device driver for Storage Class Memory (SCM). This driver
provides a block device interface for each available SCM increment.
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/block/scm_blk.c b/drivers/s390/block/scm_blk.c
new file mode 100644
index 0000000..634ad58
--- /dev/null
+++ b/drivers/s390/block/scm_blk.c
@@ -0,0 +1,414 @@
+/*
+ * 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/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 DEFINE_SPINLOCK(list_lock);
+static LIST_HEAD(inactive_requests);
+static unsigned int nr_requests = 64;
+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_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);
+ free_page((unsigned long) scmrq->aidaw);
+ 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);
+}
+
+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->aidaw = (void *) get_zeroed_page(GFP_DMA);
+ scmrq->aob = (void *) get_zeroed_page(GFP_DMA);
+ if (!scmrq->aob || !scmrq->aidaw) {
+ __scm_free_rq(scmrq);
+ return -ENOMEM;
+ }
+ INIT_LIST_HEAD(&scmrq->list);
+ spin_lock_irq(&list_lock);
+ list_add(&scmrq->list, &inactive_requests);
+ spin_unlock_irq(&list_lock);
+
+ return 0;
+}
+
+static int scm_alloc_rqs(unsigned int nrqs)
+{
+ int ret = 0;
+
+ 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;
+
+ spin_lock_irqsave(&list_lock, flags);
+ list_add(&scmrq->list, &inactive_requests);
+ spin_unlock_irqrestore(&list_lock, flags);
+}
+
+static int scm_open(struct block_device *blkdev, fmode_t mode)
+{
+ return scm_get_ref();
+}
+
+static int scm_release(struct gendisk *gendisk, fmode_t mode)
+{
+ scm_put_ref();
+ return 0;
+}
+
+static const struct block_device_operations scm_blk_devops = {
+ .owner = THIS_MODULE,
+ .open = scm_open,
+ .release = scm_release,
+};
+
+static void scm_request_prepare(struct scm_request *scmrq)
+{
+ struct scm_blk_dev *bdev = scmrq->bdev;
+ struct scm_device *scmdev = bdev->gendisk->private_data;
+ struct aidaw *aidaw = scmrq->aidaw;
+ struct msb *msb = &scmrq->aob->msb[0];
+ struct req_iterator iter;
+ struct bio_vec *bv;
+
+ msb->bs = MSB_BS_4K;
+ scmrq->aob->request.msb_count = 1;
+ msb->scm_addr = scmdev->address +
+ ((u64) blk_rq_pos(scmrq->request) << 9);
+ msb->oc = (rq_data_dir(scmrq->request) == READ) ?
+ MSB_OC_READ : MSB_OC_WRITE;
+ msb->flags |= MSB_FLAG_IDA;
+ msb->data_addr = (u64) aidaw;
+
+ rq_for_each_segment(bv, scmrq->request, iter) {
+ WARN_ON(bv->bv_offset);
+ msb->blk_count += bv->bv_len >> 12;
+ aidaw->data_addr = (u64) page_address(bv->bv_page);
+ aidaw++;
+ }
+}
+
+static inline void scm_request_init(struct scm_blk_dev *bdev,
+ struct scm_request *scmrq,
+ struct request *req)
+{
+ struct aob_rq_header *aobrq = to_aobrq(scmrq);
+ struct aob *aob = scmrq->aob;
+
+ memset(aob, 0, sizeof(*aob));
+ memset(scmrq->aidaw, 0, PAGE_SIZE);
+ aobrq->scmdev = bdev->scmdev;
+ aob->request.cmd_code = ARQB_CMD_MOVE;
+ aob->request.data = (u64) aobrq;
+ scmrq->request = req;
+ scmrq->bdev = bdev;
+ scmrq->retries = 4;
+ scmrq->error = 0;
+}
+
+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);
+}
+
+static void scm_request_requeue(struct scm_request *scmrq)
+{
+ struct scm_blk_dev *bdev = scmrq->bdev;
+
+ blk_requeue_request(bdev->rq, scmrq->request);
+ scm_request_done(scmrq);
+ scm_ensure_queue_restart(bdev);
+}
+
+static void scm_request_finish(struct scm_request *scmrq)
+{
+ blk_end_request_all(scmrq->request, scmrq->error);
+ scm_request_done(scmrq);
+}
+
+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;
+ struct request *req;
+ int ret;
+
+ while ((req = blk_peek_request(rq))) {
+ if (req->cmd_type != REQ_TYPE_FS)
+ continue;
+
+ scmrq = scm_request_fetch();
+ if (!scmrq) {
+ SCM_LOG(5, "no request");
+ scm_ensure_queue_restart(bdev);
+ return;
+ }
+ scm_request_init(bdev, scmrq, req);
+ scm_request_prepare(scmrq);
+ blk_start_request(req);
+
+ ret = scm_start_aob(scmrq->aob);
+ if (ret) {
+ SCM_LOG(5, "no subchannel");
+ scm_request_requeue(scmrq);
+ return;
+ }
+ atomic_inc(&bdev->queued_reqs);
+ }
+}
+
+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_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) {
+ if (scm_start_aob(scmrq->aob)) {
+ spin_lock_irqsave(&bdev->rq_lock, flags);
+ scm_request_requeue(scmrq);
+ spin_unlock_irqrestore(&bdev->rq_lock, flags);
+ }
+ /* Request restarted or requeued, handle next. */
+ spin_lock_irqsave(&bdev->lock, flags);
+ continue;
+ }
+ scm_request_finish(scmrq);
+ atomic_dec(&bdev->queued_reqs);
+ spin_lock_irqsave(&bdev->lock, flags);
+ }
+ spin_unlock_irqrestore(&bdev->lock, flags);
+ /* Look out for more requests. */
+ blk_run_queue(bdev->rq);
+}
+
+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;
+ 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);
+
+ 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);
+}
+
+static int __init scm_blk_init(void)
+{
+ int ret;
+
+ ret = register_blkdev(0, "scm");
+ if (ret < 0)
+ goto out;
+
+ scm_major = ret;
+ if (scm_alloc_rqs(nr_requests))
+ goto out_unreg;
+
+ scm_debug = debug_register("scm_log", 16, 1, 16);
+ if (!scm_debug)
+ 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();
+out_unreg:
+ 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);