drivers/s390/cio/ccwreq.c

   1 /*
   2  *  Handling of internal CCW device requests.
   3  *
   4  *    Copyright IBM Corp. 2009
   5  *    Author(s): Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
   6  */
   7
   8 #include <linux/types.h>
   9 #include <linux/err.h>
  10 #include <asm/ccwdev.h>
  11 #include <asm/cio.h>
  12
  13 #include "io_sch.h"
  14 #include "cio.h"
  15 #include "device.h"
  16 #include "cio_debug.h"
  17
  18 /**
  19  * lpm_adjust - adjust path mask
  20  * @lpm: path mask to adjust
  21  * @mask: mask of available paths
  22  *
  23  * Shift @lpm right until @lpm and @mask have at least one bit in common or
  24  * until @lpm is zero. Return the resulting lpm.
  25  */
  26 int lpm_adjust(int lpm, int mask)
  27 {
  28         while (lpm && ((lpm & mask) == 0))
  29                 lpm >>= 1;
  30         return lpm;
  31 }
  32
  33 /*
  34  * Adjust path mask to use next path and reset retry count. Return resulting
  35  * path mask.
  36  */
  37 static u16 ccwreq_next_path(struct ccw_device *cdev)
  38 {
  39         struct ccw_request *req = &cdev->private->req;
  40
  41         req->retries    = req->maxretries;
  42         req->mask       = lpm_adjust(req->mask >>= 1, req->lpm);
  43
  44         return req->mask;
  45 }
  46
  47 /*
  48  * Clean up device state and report to callback.
  49  */
  50 static void ccwreq_stop(struct ccw_device *cdev, int rc)
  51 {
  52         struct ccw_request *req = &cdev->private->req;
  53
  54         if (req->done)
  55                 return;
  56         req->done = 1;
  57         ccw_device_set_timeout(cdev, 0);
  58         memset(&cdev->private->irb, 0, sizeof(struct irb));
  59         if (rc && rc != -ENODEV && req->drc)
  60                 rc = req->drc;
  61         req->callback(cdev, req->data, rc);
  62 }
  63
  64 /*
  65  * (Re-)Start the operation until retries and paths are exhausted.
  66  */
  67 static void ccwreq_do(struct ccw_device *cdev)
  68 {
  69         struct ccw_request *req = &cdev->private->req;
  70         struct subchannel *sch = to_subchannel(cdev->dev.parent);
  71         struct ccw1 *cp = req->cp;
  72         int rc = -EACCES;
  73
  74         while (req->mask) {
  75                 if (req->retries-- == 0) {
  76                         /* Retries exhausted, try next path. */
  77                         ccwreq_next_path(cdev);
  78                         continue;
  79                 }
  80                 /* Perform start function. */
  81                 memset(&cdev->private->irb, 0, sizeof(struct irb));
  82                 rc = cio_start(sch, cp, (u8) req->mask);
  83                 if (rc == 0) {
  84                         /* I/O started successfully. */
  85                         ccw_device_set_timeout(cdev, req->timeout);
  86                         return;
  87                 }
  88                 if (rc == -ENODEV) {
  89                         /* Permanent device error. */
  90                         break;
  91                 }
  92                 if (rc == -EACCES) {
  93                         /* Permant path error. */
  94                         ccwreq_next_path(cdev);
  95                         continue;
  96                 }
  97                 /* Temporary improper status. */
  98                 rc = cio_clear(sch);
  99                 if (rc)
 100                         break;
 101                 return;
 102         }
 103         ccwreq_stop(cdev, rc);
 104 }
 105
 106 /**
 107  * ccw_request_start - perform I/O request
 108  * @cdev: ccw device
 109  *
 110  * Perform the I/O request specified by cdev->req.
 111  */
 112 void ccw_request_start(struct ccw_device *cdev)
 113 {
 114         struct ccw_request *req = &cdev->private->req;
 115
 116         /* Try all paths twice to counter link flapping. */
 117         req->mask       = 0x8080;
 118         req->retries    = req->maxretries;
 119         req->mask       = lpm_adjust(req->mask, req->lpm);
 120         req->drc        = 0;
 121         req->done       = 0;
 122         req->cancel     = 0;
 123         if (!req->mask)
 124                 goto out_nopath;
 125         ccwreq_do(cdev);
 126         return;
 127
 128 out_nopath:
 129         ccwreq_stop(cdev, -EACCES);
 130 }
 131
 132 /**
 133  * ccw_request_cancel - cancel running I/O request
 134  * @cdev: ccw device
 135  *
 136  * Cancel the I/O request specified by cdev->req. Return non-zero if request
 137  * has already finished, zero otherwise.
 138  */
 139 int ccw_request_cancel(struct ccw_device *cdev)
 140 {
 141         struct subchannel *sch = to_subchannel(cdev->dev.parent);
 142         struct ccw_request *req = &cdev->private->req;
 143         int rc;
 144
 145         if (req->done)
 146                 return 1;
 147         req->cancel = 1;
 148         rc = cio_clear(sch);
 149         if (rc)
 150                 ccwreq_stop(cdev, rc);
 151         return 0;
 152 }
 153
 154 /*
 155  * Return the status of the internal I/O started on the specified ccw device.
 156  * Perform BASIC SENSE if required.
 157  */
 158 static enum io_status ccwreq_status(struct ccw_device *cdev, struct irb *lcirb)
 159 {
 160         struct irb *irb = &cdev->private->irb;
 161         struct cmd_scsw *scsw = &irb->scsw.cmd;
 162
 163         /* Perform BASIC SENSE if needed. */
 164         if (ccw_device_accumulate_and_sense(cdev, lcirb))
 165                 return IO_RUNNING;
 166         /* Check for halt/clear interrupt. */
 167         if (scsw->fctl & (SCSW_FCTL_HALT_FUNC | SCSW_FCTL_CLEAR_FUNC))
 168                 return IO_KILLED;
 169         /* Check for path error. */
 170         if (scsw->cc == 3 || scsw->pno)
 171                 return IO_PATH_ERROR;
 172         /* Handle BASIC SENSE data. */
 173         if (irb->esw.esw0.erw.cons) {
 174                 CIO_TRACE_EVENT(2, "sensedata");
 175                 CIO_HEX_EVENT(2, &cdev->private->dev_id,
 176                               sizeof(struct ccw_dev_id));
 177                 CIO_HEX_EVENT(2, &cdev->private->irb.ecw, SENSE_MAX_COUNT);
 178                 /* Check for command reject. */
 179                 if (irb->ecw[0] & SNS0_CMD_REJECT)
 180                         return IO_REJECTED;
 181                 /* Assume that unexpected SENSE data implies an error. */
 182                 return IO_STATUS_ERROR;
 183         }
 184         /* Check for channel errors. */
 185         if (scsw->cstat != 0)
 186                 return IO_STATUS_ERROR;
 187         /* Check for device errors. */
 188         if (scsw->dstat & ~(DEV_STAT_CHN_END | DEV_STAT_DEV_END))
 189                 return IO_STATUS_ERROR;
 190         /* Check for final state. */
 191         if (!(scsw->dstat & DEV_STAT_DEV_END))
 192                 return IO_RUNNING;
 193         /* Check for other improper status. */
 194         if (scsw->cc == 1 && (scsw->stctl & SCSW_STCTL_ALERT_STATUS))
 195                 return IO_STATUS_ERROR;
 196         return IO_DONE;
 197 }
 198
 199 /*
 200  * Log ccw request status.
 201  */
 202 static void ccwreq_log_status(struct ccw_device *cdev, enum io_status status)
 203 {
 204         struct ccw_request *req = &cdev->private->req;
 205         struct {
 206                 struct ccw_dev_id dev_id;
 207                 u16 retries;
 208                 u8 lpm;
 209                 u8 status;
 210         }  __attribute__ ((packed)) data;
 211         data.dev_id     = cdev->private->dev_id;
 212         data.retries    = req->retries;
 213         data.lpm        = (u8) req->mask;
 214         data.status     = (u8) status;
 215         CIO_TRACE_EVENT(2, "reqstat");
 216         CIO_HEX_EVENT(2, &data, sizeof(data));
 217 }
 218
 219 /**
 220  * ccw_request_handler - interrupt handler for I/O request procedure.
 221  * @cdev: ccw device
 222  *
 223  * Handle interrupt during I/O request procedure.
 224  */
 225 void ccw_request_handler(struct ccw_device *cdev)
 226 {
 227         struct irb *irb = (struct irb *)&S390_lowcore.irb;
 228         struct ccw_request *req = &cdev->private->req;
 229         enum io_status status;
 230         int rc = -EOPNOTSUPP;
 231
 232         /* Check status of I/O request. */
 233         status = ccwreq_status(cdev, irb);
 234         if (req->filter)
 235                 status = req->filter(cdev, req->data, irb, status);
 236         if (status != IO_RUNNING)
 237                 ccw_device_set_timeout(cdev, 0);
 238         if (status != IO_DONE && status != IO_RUNNING)
 239                 ccwreq_log_status(cdev, status);
 240         switch (status) {
 241         case IO_DONE:
 242                 break;
 243         case IO_RUNNING:
 244                 return;
 245         case IO_REJECTED:
 246                 goto err;
 247         case IO_PATH_ERROR:
 248                 goto out_next_path;
 249         case IO_STATUS_ERROR:
 250                 goto out_restart;
 251         case IO_KILLED:
 252                 /* Check if request was cancelled on purpose. */
 253                 if (req->cancel) {
 254                         rc = -EIO;
 255                         goto err;
 256                 }
 257                 goto out_restart;
 258         }
 259         /* Check back with request initiator. */
 260         if (!req->check)
 261                 goto out;
 262         switch (req->check(cdev, req->data)) {
 263         case 0:
 264                 break;
 265         case -EAGAIN:
 266                 goto out_restart;
 267         case -EACCES:
 268                 goto out_next_path;
 269         default:
 270                 goto err;
 271         }
 272 out:
 273         ccwreq_stop(cdev, 0);
 274         return;
 275
 276 out_next_path:
 277         /* Try next path and restart I/O. */
 278         if (!ccwreq_next_path(cdev)) {
 279                 rc = -EACCES;
 280                 goto err;
 281         }
 282 out_restart:
 283         /* Restart. */
 284         ccwreq_do(cdev);
 285         return;
 286 err:
 287         ccwreq_stop(cdev, rc);
 288 }
 289
 290
 291 /**
 292  * ccw_request_timeout - timeout handler for I/O request procedure
 293  * @cdev: ccw device
 294  *
 295  * Handle timeout during I/O request procedure.
 296  */
 297 void ccw_request_timeout(struct ccw_device *cdev)
 298 {
 299         struct subchannel *sch = to_subchannel(cdev->dev.parent);
 300         struct ccw_request *req = &cdev->private->req;
 301         int rc;
 302
 303         if (!ccwreq_next_path(cdev)) {
 304                 /* set the final return code for this request */
 305                 req->drc = -ETIME;
 306         }
 307         rc = cio_clear(sch);
 308         if (rc)
 309                 goto err;
 310         return;
 311
 312 err:
 313         ccwreq_stop(cdev, rc);
 314 }
 315
 316 /**
 317  * ccw_request_notoper - notoper handler for I/O request procedure
 318  * @cdev: ccw device
 319  *
 320  * Handle timeout during I/O request procedure.
 321  */
 322 void ccw_request_notoper(struct ccw_device *cdev)
 323 {
 324         ccwreq_stop(cdev, -ENODEV);
 325 }