[S390] cio: consistent infrastructure for internal I/O requests

Reduce code duplication by introducing a central infrastructure to
perform an internal I/O operation on a CCW device.

Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 327 insertions, 0 deletions

diff --git a/drivers/s390/cio/ccwreq.c b/drivers/s390/cio/ccwreq.c
new file mode 100644
index 000000000000..a6e205a384b2
--- /dev/null
+++ b/drivers/s390/cio/ccwreq.c
@@ -0,0 +1,327 @@
+/*
+ *  Handling of internal CCW device requests.
+ *
+ *    Copyright IBM Corp. 2009
+ *    Author(s): Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
+ */
+
+#include <linux/types.h>
+#include <linux/err.h>
+#include <asm/ccwdev.h>
+#include <asm/cio.h>
+
+#include "io_sch.h"
+#include "cio.h"
+#include "device.h"
+#include "cio_debug.h"
+
+/**
+ * lpm_adjust - adjust path mask
+ * @lpm: path mask to adjust
+ * @mask: mask of available paths
+ *
+ * Shift @lpm right until @lpm and @mask have at least one bit in common or
+ * until @lpm is zero. Return the resulting lpm.
+ */
+int lpm_adjust(int lpm, int mask)
+{
+        while (lpm && ((lpm & mask) == 0))
+                lpm >>= 1;
+        return lpm;
+}
+
+/*
+ * Adjust path mask to use next path and reset retry count. Return resulting
+ * path mask.
+ */
+static u16 ccwreq_next_path(struct ccw_device *cdev)
+{
+        struct ccw_request *req = &cdev->private->req;
+
+        req->retries    = req->maxretries;
+        req->mask       = lpm_adjust(req->mask >>= 1, req->lpm);
+
+        return req->mask;
+}
+
+/*
+ * Clean up device state and report to callback.
+ */
+static void ccwreq_stop(struct ccw_device *cdev, int rc)
+{
+        struct subchannel *sch = to_subchannel(cdev->dev.parent);
+        struct ccw_request *req = &cdev->private->req;
+
+        if (req->done)
+                return;
+        req->done = 1;
+        ccw_device_set_timeout(cdev, 0);
+        memset(&cdev->private->irb, 0, sizeof(struct irb));
+        sch->lpm = sch->schib.pmcw.pam;
+        if (rc && rc != -ENODEV && req->drc)
+                rc = req->drc;
+        req->callback(cdev, req->data, rc);
+}
+
+/*
+ * (Re-)Start the operation until retries and paths are exhausted.
+ */
+static void ccwreq_do(struct ccw_device *cdev)
+{
+        struct ccw_request *req = &cdev->private->req;
+        struct subchannel *sch = to_subchannel(cdev->dev.parent);
+        struct ccw1 *cp = req->cp;
+        int rc = -EACCES;
+
+        while (req->mask) {
+                if (req->retries-- == 0) {
+                        /* Retries exhausted, try next path. */
+                        ccwreq_next_path(cdev);
+                        continue;
+                }
+                /* Perform start function. */
+                sch->lpm = 0xff;
+                memset(&cdev->private->irb, 0, sizeof(struct irb));
+                rc = cio_start(sch, cp, req->mask);
+                if (rc == 0) {
+                        /* I/O started successfully. */
+                        ccw_device_set_timeout(cdev, req->timeout);
+                        return;
+                }
+                if (rc == -ENODEV) {
+                        /* Permanent device error. */
+                        break;
+                }
+                if (rc == -EACCES) {
+                        /* Permant path error. */
+                        ccwreq_next_path(cdev);
+                        continue;
+                }
+                /* Temporary improper status. */
+                rc = cio_clear(sch);
+                if (rc)
+                        break;
+                return;
+        }
+        ccwreq_stop(cdev, rc);
+}
+
+/**
+ * ccw_request_start - perform I/O request
+ * @cdev: ccw device
+ *
+ * Perform the I/O request specified by cdev->req.
+ */
+void ccw_request_start(struct ccw_device *cdev)
+{
+        struct ccw_request *req = &cdev->private->req;
+
+        req->mask       = 0x80;
+        req->retries    = req->maxretries;
+        req->mask       = lpm_adjust(req->mask, req->lpm);
+        req->drc        = 0;
+        req->done       = 0;
+        req->cancel     = 0;
+        if (!req->mask)
+                goto out_nopath;
+        ccwreq_do(cdev);
+        return;
+
+out_nopath:
+        ccwreq_stop(cdev, -EACCES);
+}
+
+/**
+ * ccw_request_cancel - cancel running I/O request
+ * @cdev: ccw device
+ *
+ * Cancel the I/O request specified by cdev->req. Return non-zero if request
+ * has already finished, zero otherwise.
+ */
+int ccw_request_cancel(struct ccw_device *cdev)
+{
+        struct subchannel *sch = to_subchannel(cdev->dev.parent);
+        struct ccw_request *req = &cdev->private->req;
+        int rc;
+
+        if (req->done)
+                return 1;
+        req->cancel = 1;
+        rc = cio_clear(sch);
+        if (rc)
+                ccwreq_stop(cdev, rc);
+        return 0;
+}
+
+/*
+ * Return the status of the internal I/O started on the specified ccw device.
+ * Perform BASIC SENSE if required.
+ */
+static enum io_status ccwreq_status(struct ccw_device *cdev, struct irb *lcirb)
+{
+        struct irb *irb = &cdev->private->irb;
+        struct cmd_scsw *scsw = &irb->scsw.cmd;
+
+        /* Perform BASIC SENSE if needed. */
+        if (ccw_device_accumulate_and_sense(cdev, lcirb))
+                return IO_RUNNING;
+        /* Check for halt/clear interrupt. */
+        if (scsw->fctl & (SCSW_FCTL_HALT_FUNC | SCSW_FCTL_CLEAR_FUNC))
+                return IO_KILLED;
+        /* Check for path error. */
+        if (scsw->cc == 3 || scsw->pno)
+                return IO_PATH_ERROR;
+        /* Handle BASIC SENSE data. */
+        if (irb->esw.esw0.erw.cons) {
+                CIO_TRACE_EVENT(2, "sensedata");
+                CIO_HEX_EVENT(2, &cdev->private->dev_id,
+                              sizeof(struct ccw_dev_id));
+                CIO_HEX_EVENT(2, &cdev->private->irb.ecw, SENSE_MAX_COUNT);
+                /* Check for command reject. */
+                if (irb->ecw[0] & SNS0_CMD_REJECT)
+                        return IO_REJECTED;
+                /* Assume that unexpected SENSE data implies an error. */
+                return IO_STATUS_ERROR;
+        }
+        /* Check for channel errors. */
+        if (scsw->cstat != 0)
+                return IO_STATUS_ERROR;
+        /* Check for device errors. */
+        if (scsw->dstat & ~(DEV_STAT_CHN_END | DEV_STAT_DEV_END))
+                return IO_STATUS_ERROR;
+        /* Check for final state. */
+        if (!(scsw->dstat & DEV_STAT_DEV_END))
+                return IO_RUNNING;
+        /* Check for other improper status. */
+        if (scsw->cc == 1 && (scsw->stctl & SCSW_STCTL_ALERT_STATUS))
+                return IO_STATUS_ERROR;
+        return IO_DONE;
+}
+
+/*
+ * Log ccw request status.
+ */
+static void ccwreq_log_status(struct ccw_device *cdev, enum io_status status)
+{
+        struct ccw_request *req = &cdev->private->req;
+        struct {
+                struct ccw_dev_id dev_id;
+                u16 retries;
+                u8 lpm;
+                u8 status;
+        }  __attribute__ ((packed)) data;
+        data.dev_id     = cdev->private->dev_id;
+        data.retries    = req->retries;
+        data.lpm        = req->mask;
+        data.status     = (u8) status;
+        CIO_TRACE_EVENT(2, "reqstat");
+        CIO_HEX_EVENT(2, &data, sizeof(data));
+}
+
+/**
+ * ccw_request_handler - interrupt handler for I/O request procedure.
+ * @cdev: ccw device
+ *
+ * Handle interrupt during I/O request procedure.
+ */
+void ccw_request_handler(struct ccw_device *cdev)
+{
+        struct ccw_request *req = &cdev->private->req;
+        struct irb *irb = (struct irb *) __LC_IRB;
+        enum io_status status;
+        int rc = -EOPNOTSUPP;
+
+        /* Check status of I/O request. */
+        status = ccwreq_status(cdev, irb);
+        if (req->filter)
+                status = req->filter(cdev, req->data, irb, status);
+        if (status != IO_RUNNING)
+                ccw_device_set_timeout(cdev, 0);
+        if (status != IO_DONE && status != IO_RUNNING)
+                ccwreq_log_status(cdev, status);
+        switch (status) {
+        case IO_DONE:
+                break;
+        case IO_RUNNING:
+                return;
+        case IO_REJECTED:
+                goto err;
+        case IO_PATH_ERROR:
+                goto out_next_path;
+        case IO_STATUS_ERROR:
+                goto out_restart;
+        case IO_KILLED:
+                /* Check if request was cancelled on purpose. */
+                if (req->cancel) {
+                        rc = -EIO;
+                        goto err;
+                }
+                goto out_restart;
+        }
+        /* Check back with request initiator. */
+        if (!req->check)
+                goto out;
+        switch (req->check(cdev, req->data)) {
+        case 0:
+                break;
+        case -EAGAIN:
+                goto out_restart;
+        case -EACCES:
+                goto out_next_path;
+        default:
+                goto err;
+        }
+out:
+        ccwreq_stop(cdev, 0);
+        return;
+
+out_next_path:
+        /* Try next path and restart I/O. */
+        if (!ccwreq_next_path(cdev)) {
+                rc = -EACCES;
+                goto err;
+        }
+out_restart:
+        /* Restart. */
+        ccwreq_do(cdev);
+        return;
+err:
+        ccwreq_stop(cdev, rc);
+}
+
+
+/**
+ * ccw_request_timeout - timeout handler for I/O request procedure
+ * @cdev: ccw device
+ *
+ * Handle timeout during I/O request procedure.
+ */
+void ccw_request_timeout(struct ccw_device *cdev)
+{
+        struct subchannel *sch = to_subchannel(cdev->dev.parent);
+        struct ccw_request *req = &cdev->private->req;
+        int rc;
+
+        if (!ccwreq_next_path(cdev)) {
+                /* set the final return code for this request */
+                req->drc = -ETIME;
+        }
+        rc = cio_clear(sch);
+        if (rc)
+                goto err;
+        return;
+
+err:
+        ccwreq_stop(cdev, rc);
+}
+
+/**
+ * ccw_request_notoper - notoper handler for I/O request procedure
+ * @cdev: ccw device
+ *
+ * Handle timeout during I/O request procedure.
+ */
+void ccw_request_notoper(struct ccw_device *cdev)
+{
+        ccwreq_stop(cdev, -ENODEV);
+}