1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  Handling of internal CCW device requests.
4  *
5  *    Copyright IBM Corp. 2009, 2011
6  *    Author(s): Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
7  */
8 
9 #define KMSG_COMPONENT "cio"
10 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
11 
12 #include <linux/types.h>
13 #include <linux/err.h>
14 #include <asm/ccwdev.h>
15 #include <asm/cio.h>
16 
17 #include "io_sch.h"
18 #include "cio.h"
19 #include "device.h"
20 #include "cio_debug.h"
21 
22 /**
23  * lpm_adjust - adjust path mask
24  * @lpm: path mask to adjust
25  * @mask: mask of available paths
26  *
27  * Shift @lpm right until @lpm and @mask have at least one bit in common or
28  * until @lpm is zero. Return the resulting lpm.
29  */
lpm_adjust(int lpm,int mask)30 int lpm_adjust(int lpm, int mask)
31 {
32 	while (lpm && ((lpm & mask) == 0))
33 		lpm >>= 1;
34 	return lpm;
35 }
36 
37 /*
38  * Adjust path mask to use next path and reset retry count. Return resulting
39  * path mask.
40  */
ccwreq_next_path(struct ccw_device * cdev)41 static u16 ccwreq_next_path(struct ccw_device *cdev)
42 {
43 	struct ccw_request *req = &cdev->private->req;
44 
45 	if (!req->singlepath) {
46 		req->mask = 0;
47 		goto out;
48 	}
49 	req->retries	= req->maxretries;
50 	req->mask	= lpm_adjust(req->mask >> 1, req->lpm);
51 out:
52 	return req->mask;
53 }
54 
55 /*
56  * Clean up device state and report to callback.
57  */
ccwreq_stop(struct ccw_device * cdev,int rc)58 static void ccwreq_stop(struct ccw_device *cdev, int rc)
59 {
60 	struct ccw_request *req = &cdev->private->req;
61 
62 	if (req->done)
63 		return;
64 	req->done = 1;
65 	ccw_device_set_timeout(cdev, 0);
66 	memset(&cdev->private->irb, 0, sizeof(struct irb));
67 	if (rc && rc != -ENODEV && req->drc)
68 		rc = req->drc;
69 	req->callback(cdev, req->data, rc);
70 }
71 
72 /*
73  * (Re-)Start the operation until retries and paths are exhausted.
74  */
ccwreq_do(struct ccw_device * cdev)75 static void ccwreq_do(struct ccw_device *cdev)
76 {
77 	struct ccw_request *req = &cdev->private->req;
78 	struct subchannel *sch = to_subchannel(cdev->dev.parent);
79 	struct ccw1 *cp = req->cp;
80 	int rc = -EACCES;
81 
82 	while (req->mask) {
83 		if (req->retries-- == 0) {
84 			/* Retries exhausted, try next path. */
85 			ccwreq_next_path(cdev);
86 			continue;
87 		}
88 		/* Perform start function. */
89 		memset(&cdev->private->irb, 0, sizeof(struct irb));
90 		rc = cio_start(sch, cp, (u8) req->mask);
91 		if (rc == 0) {
92 			/* I/O started successfully. */
93 			ccw_device_set_timeout(cdev, req->timeout);
94 			return;
95 		}
96 		if (rc == -ENODEV) {
97 			/* Permanent device error. */
98 			break;
99 		}
100 		if (rc == -EACCES) {
101 			/* Permant path error. */
102 			ccwreq_next_path(cdev);
103 			continue;
104 		}
105 		/* Temporary improper status. */
106 		rc = cio_clear(sch);
107 		if (rc)
108 			break;
109 		return;
110 	}
111 	ccwreq_stop(cdev, rc);
112 }
113 
114 /**
115  * ccw_request_start - perform I/O request
116  * @cdev: ccw device
117  *
118  * Perform the I/O request specified by cdev->req.
119  */
ccw_request_start(struct ccw_device * cdev)120 void ccw_request_start(struct ccw_device *cdev)
121 {
122 	struct ccw_request *req = &cdev->private->req;
123 
124 	if (req->singlepath) {
125 		/* Try all paths twice to counter link flapping. */
126 		req->mask = 0x8080;
127 	} else
128 		req->mask = req->lpm;
129 
130 	req->retries	= req->maxretries;
131 	req->mask	= lpm_adjust(req->mask, req->lpm);
132 	req->drc	= 0;
133 	req->done	= 0;
134 	req->cancel	= 0;
135 	if (!req->mask)
136 		goto out_nopath;
137 	ccwreq_do(cdev);
138 	return;
139 
140 out_nopath:
141 	ccwreq_stop(cdev, -EACCES);
142 }
143 
144 /**
145  * ccw_request_cancel - cancel running I/O request
146  * @cdev: ccw device
147  *
148  * Cancel the I/O request specified by cdev->req. Return non-zero if request
149  * has already finished, zero otherwise.
150  */
ccw_request_cancel(struct ccw_device * cdev)151 int ccw_request_cancel(struct ccw_device *cdev)
152 {
153 	struct subchannel *sch = to_subchannel(cdev->dev.parent);
154 	struct ccw_request *req = &cdev->private->req;
155 	int rc;
156 
157 	if (req->done)
158 		return 1;
159 	req->cancel = 1;
160 	rc = cio_clear(sch);
161 	if (rc)
162 		ccwreq_stop(cdev, rc);
163 	return 0;
164 }
165 
166 /*
167  * Return the status of the internal I/O started on the specified ccw device.
168  * Perform BASIC SENSE if required.
169  */
ccwreq_status(struct ccw_device * cdev,struct irb * lcirb)170 static enum io_status ccwreq_status(struct ccw_device *cdev, struct irb *lcirb)
171 {
172 	struct irb *irb = &cdev->private->irb;
173 	struct cmd_scsw *scsw = &irb->scsw.cmd;
174 	enum uc_todo todo;
175 
176 	/* Perform BASIC SENSE if needed. */
177 	if (ccw_device_accumulate_and_sense(cdev, lcirb))
178 		return IO_RUNNING;
179 	/* Check for halt/clear interrupt. */
180 	if (scsw->fctl & (SCSW_FCTL_HALT_FUNC | SCSW_FCTL_CLEAR_FUNC))
181 		return IO_KILLED;
182 	/* Check for path error. */
183 	if (scsw->cc == 3 || scsw->pno)
184 		return IO_PATH_ERROR;
185 	/* Handle BASIC SENSE data. */
186 	if (irb->esw.esw0.erw.cons) {
187 		CIO_TRACE_EVENT(2, "sensedata");
188 		CIO_HEX_EVENT(2, &cdev->private->dev_id,
189 			      sizeof(struct ccw_dev_id));
190 		CIO_HEX_EVENT(2, &cdev->private->irb.ecw, SENSE_MAX_COUNT);
191 		/* Check for command reject. */
192 		if (irb->ecw[0] & SNS0_CMD_REJECT)
193 			return IO_REJECTED;
194 		/* Ask the driver what to do */
195 		if (cdev->drv && cdev->drv->uc_handler) {
196 			todo = cdev->drv->uc_handler(cdev, lcirb);
197 			CIO_TRACE_EVENT(2, "uc_response");
198 			CIO_HEX_EVENT(2, &todo, sizeof(todo));
199 			switch (todo) {
200 			case UC_TODO_RETRY:
201 				return IO_STATUS_ERROR;
202 			case UC_TODO_RETRY_ON_NEW_PATH:
203 				return IO_PATH_ERROR;
204 			case UC_TODO_STOP:
205 				return IO_REJECTED;
206 			default:
207 				return IO_STATUS_ERROR;
208 			}
209 		}
210 		/* Assume that unexpected SENSE data implies an error. */
211 		return IO_STATUS_ERROR;
212 	}
213 	/* Check for channel errors. */
214 	if (scsw->cstat != 0)
215 		return IO_STATUS_ERROR;
216 	/* Check for device errors. */
217 	if (scsw->dstat & ~(DEV_STAT_CHN_END | DEV_STAT_DEV_END))
218 		return IO_STATUS_ERROR;
219 	/* Check for final state. */
220 	if (!(scsw->dstat & DEV_STAT_DEV_END))
221 		return IO_RUNNING;
222 	/* Check for other improper status. */
223 	if (scsw->cc == 1 && (scsw->stctl & SCSW_STCTL_ALERT_STATUS))
224 		return IO_STATUS_ERROR;
225 	return IO_DONE;
226 }
227 
228 /*
229  * Log ccw request status.
230  */
ccwreq_log_status(struct ccw_device * cdev,enum io_status status)231 static void ccwreq_log_status(struct ccw_device *cdev, enum io_status status)
232 {
233 	struct ccw_request *req = &cdev->private->req;
234 	struct {
235 		struct ccw_dev_id dev_id;
236 		u16 retries;
237 		u8 lpm;
238 		u8 status;
239 	}  __attribute__ ((packed)) data;
240 	data.dev_id	= cdev->private->dev_id;
241 	data.retries	= req->retries;
242 	data.lpm	= (u8) req->mask;
243 	data.status	= (u8) status;
244 	CIO_TRACE_EVENT(2, "reqstat");
245 	CIO_HEX_EVENT(2, &data, sizeof(data));
246 }
247 
248 /**
249  * ccw_request_handler - interrupt handler for I/O request procedure.
250  * @cdev: ccw device
251  *
252  * Handle interrupt during I/O request procedure.
253  */
ccw_request_handler(struct ccw_device * cdev)254 void ccw_request_handler(struct ccw_device *cdev)
255 {
256 	struct irb *irb = this_cpu_ptr(&cio_irb);
257 	struct ccw_request *req = &cdev->private->req;
258 	enum io_status status;
259 	int rc = -EOPNOTSUPP;
260 
261 	/* Check status of I/O request. */
262 	status = ccwreq_status(cdev, irb);
263 	if (req->filter)
264 		status = req->filter(cdev, req->data, irb, status);
265 	if (status != IO_RUNNING)
266 		ccw_device_set_timeout(cdev, 0);
267 	if (status != IO_DONE && status != IO_RUNNING)
268 		ccwreq_log_status(cdev, status);
269 	switch (status) {
270 	case IO_DONE:
271 		break;
272 	case IO_RUNNING:
273 		return;
274 	case IO_REJECTED:
275 		goto err;
276 	case IO_PATH_ERROR:
277 		goto out_next_path;
278 	case IO_STATUS_ERROR:
279 		goto out_restart;
280 	case IO_KILLED:
281 		/* Check if request was cancelled on purpose. */
282 		if (req->cancel) {
283 			rc = -EIO;
284 			goto err;
285 		}
286 		goto out_restart;
287 	}
288 	/* Check back with request initiator. */
289 	if (!req->check)
290 		goto out;
291 	switch (req->check(cdev, req->data)) {
292 	case 0:
293 		break;
294 	case -EAGAIN:
295 		goto out_restart;
296 	case -EACCES:
297 		goto out_next_path;
298 	default:
299 		goto err;
300 	}
301 out:
302 	ccwreq_stop(cdev, 0);
303 	return;
304 
305 out_next_path:
306 	/* Try next path and restart I/O. */
307 	if (!ccwreq_next_path(cdev)) {
308 		rc = -EACCES;
309 		goto err;
310 	}
311 out_restart:
312 	/* Restart. */
313 	ccwreq_do(cdev);
314 	return;
315 err:
316 	ccwreq_stop(cdev, rc);
317 }
318 
319 
320 /**
321  * ccw_request_timeout - timeout handler for I/O request procedure
322  * @cdev: ccw device
323  *
324  * Handle timeout during I/O request procedure.
325  */
ccw_request_timeout(struct ccw_device * cdev)326 void ccw_request_timeout(struct ccw_device *cdev)
327 {
328 	struct subchannel *sch = to_subchannel(cdev->dev.parent);
329 	struct ccw_request *req = &cdev->private->req;
330 	int rc = -ENODEV, chp;
331 
332 	if (cio_update_schib(sch))
333 		goto err;
334 
335 	for (chp = 0; chp < 8; chp++) {
336 		if ((0x80 >> chp) & sch->schib.pmcw.lpum)
337 			pr_warn("%s: No interrupt was received within %lus (CS=%02x, DS=%02x, CHPID=%x.%02x)\n",
338 				dev_name(&cdev->dev), req->timeout / HZ,
339 				scsw_cstat(&sch->schib.scsw),
340 				scsw_dstat(&sch->schib.scsw),
341 				sch->schid.cssid,
342 				sch->schib.pmcw.chpid[chp]);
343 	}
344 
345 	if (!ccwreq_next_path(cdev)) {
346 		/* set the final return code for this request */
347 		req->drc = -ETIME;
348 	}
349 	rc = cio_clear(sch);
350 	if (rc)
351 		goto err;
352 	return;
353 
354 err:
355 	ccwreq_stop(cdev, rc);
356 }
357 
358 /**
359  * ccw_request_notoper - notoper handler for I/O request procedure
360  * @cdev: ccw device
361  *
362  * Handle notoper during I/O request procedure.
363  */
ccw_request_notoper(struct ccw_device * cdev)364 void ccw_request_notoper(struct ccw_device *cdev)
365 {
366 	ccwreq_stop(cdev, -ENODEV);
367 }
368