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>

5 files changed, 597 insertions, 0 deletions

diff --git a/drivers/s390/block/Kconfig b/drivers/s390/block/Kconfig
index 8e477bb1f3f6..18178b64e89a 100644
--- a/drivers/s390/block/Kconfig
+++ b/drivers/s390/block/Kconfig
@@ -70,3 +70,14 @@ config DASD_EER
           This driver provides a character device interface to the
           DASD extended error reporting. This is only needed if you want to
           use applications written for the EER facility.
+
+config SCM_BLOCK
+        def_tristate m
+        prompt "Support for Storage Class Memory"
+        depends on S390 && BLOCK && EADM_SCH && SCM_BUS
+        help
+          Block device driver for Storage Class Memory (SCM). This driver
+          provides a block device interface for each available SCM increment.
+
+          To compile this driver as a module, choose M here: the
+          module will be called scm_block.
diff --git a/drivers/s390/block/Makefile b/drivers/s390/block/Makefile
index 0a89e080b389..b64e2b32c753 100644
--- a/drivers/s390/block/Makefile
+++ b/drivers/s390/block/Makefile
@@ -17,3 +17,6 @@ obj-$(CONFIG_DASD_ECKD) += dasd_eckd_mod.o
 obj-$(CONFIG_DASD_FBA)  += dasd_fba_mod.o
 obj-$(CONFIG_BLK_DEV_XPRAM) += xpram.o
 obj-$(CONFIG_DCSSBLK) += dcssblk.o
+
+scm_block-objs := scm_drv.o scm_blk.o
+obj-$(CONFIG_SCM_BLOCK) += scm_block.o
diff --git a/drivers/s390/block/scm_blk.c b/drivers/s390/block/scm_blk.c
new file mode 100644
index 000000000000..634ad58cbef6
--- /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);
diff --git a/drivers/s390/block/scm_blk.h b/drivers/s390/block/scm_blk.h
new file mode 100644
index 000000000000..5aba5612588f
--- /dev/null
+++ b/drivers/s390/block/scm_blk.h
@@ -0,0 +1,79 @@
+#ifndef SCM_BLK_H
+#define SCM_BLK_H
+
+#include <linux/interrupt.h>
+#include <linux/spinlock.h>
+#include <linux/blkdev.h>
+#include <linux/genhd.h>
+#include <linux/list.h>
+
+#include <asm/debug.h>
+#include <asm/eadm.h>
+
+#define SCM_NR_PARTS 8
+#define SCM_QUEUE_DELAY 5
+
+struct scm_blk_dev {
+        struct tasklet_struct tasklet;
+        struct request_queue *rq;
+        struct gendisk *gendisk;
+        struct scm_device *scmdev;
+        spinlock_t rq_lock;     /* guard the request queue */
+        spinlock_t lock;        /* guard the rest of the blockdev */
+        atomic_t queued_reqs;
+        struct list_head finished_requests;
+};
+
+struct scm_request {
+        struct scm_blk_dev *bdev;
+        struct request *request;
+        struct aidaw *aidaw;
+        struct aob *aob;
+        struct list_head list;
+        u8 retries;
+        int error;
+};
+
+#define to_aobrq(rq) container_of((void *) rq, struct aob_rq_header, data)
+
+int scm_blk_dev_setup(struct scm_blk_dev *, struct scm_device *);
+void scm_blk_dev_cleanup(struct scm_blk_dev *);
+void scm_blk_irq(struct scm_device *, void *, int);
+
+int scm_drv_init(void);
+void scm_drv_cleanup(void);
+
+
+extern debug_info_t *scm_debug;
+
+#define SCM_LOG(imp, txt) do {                                  \
+                debug_text_event(scm_debug, imp, txt);          \
+        } while (0)
+
+static inline void SCM_LOG_HEX(int level, void *data, int length)
+{
+        if (level > scm_debug->level)
+                return;
+        while (length > 0) {
+                debug_event(scm_debug, level, data, length);
+                length -= scm_debug->buf_size;
+                data += scm_debug->buf_size;
+        }
+}
+
+static inline void SCM_LOG_STATE(int level, struct scm_device *scmdev)
+{
+        struct {
+                u64 address;
+                u8 oper_state;
+                u8 rank;
+        } __packed data = {
+                .address = scmdev->address,
+                .oper_state = scmdev->attrs.oper_state,
+                .rank = scmdev->attrs.rank,
+        };
+
+        SCM_LOG_HEX(level, &data, sizeof(data));
+}
+
+#endif /* SCM_BLK_H */
diff --git a/drivers/s390/block/scm_drv.c b/drivers/s390/block/scm_drv.c
new file mode 100644
index 000000000000..fce711a63060
--- /dev/null
+++ b/drivers/s390/block/scm_drv.c
@@ -0,0 +1,90 @@
+/*
+ * Device 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/module.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <asm/eadm.h>
+#include "scm_blk.h"
+
+static void notify(struct scm_device *scmdev)
+{
+        pr_info("%lu: The capabilities of the SCM increment changed\n",
+                (unsigned long) scmdev->address);
+        SCM_LOG(2, "State changed");
+        SCM_LOG_STATE(2, scmdev);
+}
+
+static int scm_probe(struct scm_device *scmdev)
+{
+        struct scm_blk_dev *bdev;
+        int ret;
+
+        SCM_LOG(2, "probe");
+        SCM_LOG_STATE(2, scmdev);
+
+        if (scmdev->attrs.oper_state != OP_STATE_GOOD)
+                return -EINVAL;
+
+        bdev = kzalloc(sizeof(*bdev), GFP_KERNEL);
+        if (!bdev)
+                return -ENOMEM;
+
+        spin_lock_irq(&scmdev->lock);
+        dev_set_drvdata(&scmdev->dev, bdev);
+        spin_unlock_irq(&scmdev->lock);
+
+        ret = scm_blk_dev_setup(bdev, scmdev);
+        if (ret) {
+                spin_lock_irq(&scmdev->lock);
+                dev_set_drvdata(&scmdev->dev, NULL);
+                spin_unlock_irq(&scmdev->lock);
+                kfree(bdev);
+                goto out;
+        }
+
+out:
+        return ret;
+}
+
+static int scm_remove(struct scm_device *scmdev)
+{
+        struct scm_blk_dev *bdev;
+
+        spin_lock_irq(&scmdev->lock);
+        bdev = dev_get_drvdata(&scmdev->dev);
+        dev_set_drvdata(&scmdev->dev, NULL);
+        spin_unlock_irq(&scmdev->lock);
+        scm_blk_dev_cleanup(bdev);
+        kfree(bdev);
+
+        return 0;
+}
+
+static struct scm_driver scm_drv = {
+        .drv = {
+                .name = "scm_block",
+                .owner = THIS_MODULE,
+        },
+        .notify = notify,
+        .probe = scm_probe,
+        .remove = scm_remove,
+        .handler = scm_blk_irq,
+};
+
+int __init scm_drv_init(void)
+{
+        return scm_driver_register(&scm_drv);
+}
+
+void scm_drv_cleanup(void)
+{
+        scm_driver_unregister(&scm_drv);
+}