ccwreq.c revision 63aef00b55d37e9fad837a8b38a2c261f0d32041 
1/*
2 *  Handling of internal CCW device requests.
3 *
4 *    Copyright IBM Corp. 2009, 2011
5 *    Author(s): Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
6 */
7
8#define KMSG_COMPONENT "cio"
9#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
10
11#include <linux/types.h>
12#include <linux/err.h>
13#include <asm/ccwdev.h>
14#include <asm/cio.h>
15
16#include "io_sch.h"
17#include "cio.h"
18#include "device.h"
19#include "cio_debug.h"
20
21/**
22 * lpm_adjust - adjust path mask
23 * @lpm: path mask to adjust
24 * @mask: mask of available paths
25 *
26 * Shift @lpm right until @lpm and @mask have at least one bit in common or
27 * until @lpm is zero. Return the resulting lpm.
28 */
29int lpm_adjust(int lpm, int mask)
30{
31	while (lpm && ((lpm & mask) == 0))
32		lpm >>= 1;
33	return lpm;
34}
35
36/*
37 * Adjust path mask to use next path and reset retry count. Return resulting
38 * path mask.
39 */
40static u16 ccwreq_next_path(struct ccw_device *cdev)
41{
42	struct ccw_request *req = &cdev->private->req;
43
44	if (!req->singlepath) {
45		req->mask = 0;
46		goto out;
47	}
48	req->retries	= req->maxretries;
49	req->mask	= lpm_adjust(req->mask >> 1, req->lpm);
50out:
51	return req->mask;
52}
53
54/*
55 * Clean up device state and report to callback.
56 */
57static void ccwreq_stop(struct ccw_device *cdev, int rc)
58{
59	struct ccw_request *req = &cdev->private->req;
60
61	if (req->done)
62		return;
63	req->done = 1;
64	ccw_device_set_timeout(cdev, 0);
65	memset(&cdev->private->irb, 0, sizeof(struct irb));
66	if (rc && rc != -ENODEV && req->drc)
67		rc = req->drc;
68	req->callback(cdev, req->data, rc);
69}
70
71/*
72 * (Re-)Start the operation until retries and paths are exhausted.
73 */
74static void ccwreq_do(struct ccw_device *cdev)
75{
76	struct ccw_request *req = &cdev->private->req;
77	struct subchannel *sch = to_subchannel(cdev->dev.parent);
78	struct ccw1 *cp = req->cp;
79	int rc = -EACCES;
80
81	while (req->mask) {
82		if (req->retries-- == 0) {
83			/* Retries exhausted, try next path. */
84			ccwreq_next_path(cdev);
85			continue;
86		}
87		/* Perform start function. */
88		memset(&cdev->private->irb, 0, sizeof(struct irb));
89		rc = cio_start(sch, cp, (u8) req->mask);
90		if (rc == 0) {
91			/* I/O started successfully. */
92			ccw_device_set_timeout(cdev, req->timeout);
93			return;
94		}
95		if (rc == -ENODEV) {
96			/* Permanent device error. */
97			break;
98		}
99		if (rc == -EACCES) {
100			/* Permant path error. */
101			ccwreq_next_path(cdev);
102			continue;
103		}
104		/* Temporary improper status. */
105		rc = cio_clear(sch);
106		if (rc)
107			break;
108		return;
109	}
110	ccwreq_stop(cdev, rc);
111}
112
113/**
114 * ccw_request_start - perform I/O request
115 * @cdev: ccw device
116 *
117 * Perform the I/O request specified by cdev->req.
118 */
119void ccw_request_start(struct ccw_device *cdev)
120{
121	struct ccw_request *req = &cdev->private->req;
122
123	if (req->singlepath) {
124		/* Try all paths twice to counter link flapping. */
125		req->mask = 0x8080;
126	} else
127		req->mask = req->lpm;
128
129	req->retries	= req->maxretries;
130	req->mask	= lpm_adjust(req->mask, req->lpm);
131	req->drc	= 0;
132	req->done	= 0;
133	req->cancel	= 0;
134	if (!req->mask)
135		goto out_nopath;
136	ccwreq_do(cdev);
137	return;
138
139out_nopath:
140	ccwreq_stop(cdev, -EACCES);
141}
142
143/**
144 * ccw_request_cancel - cancel running I/O request
145 * @cdev: ccw device
146 *
147 * Cancel the I/O request specified by cdev->req. Return non-zero if request
148 * has already finished, zero otherwise.
149 */
150int ccw_request_cancel(struct ccw_device *cdev)
151{
152	struct subchannel *sch = to_subchannel(cdev->dev.parent);
153	struct ccw_request *req = &cdev->private->req;
154	int rc;
155
156	if (req->done)
157		return 1;
158	req->cancel = 1;
159	rc = cio_clear(sch);
160	if (rc)
161		ccwreq_stop(cdev, rc);
162	return 0;
163}
164
165/*
166 * Return the status of the internal I/O started on the specified ccw device.
167 * Perform BASIC SENSE if required.
168 */
169static enum io_status ccwreq_status(struct ccw_device *cdev, struct irb *lcirb)
170{
171	struct irb *irb = &cdev->private->irb;
172	struct cmd_scsw *scsw = &irb->scsw.cmd;
173	enum uc_todo todo;
174
175	/* Perform BASIC SENSE if needed. */
176	if (ccw_device_accumulate_and_sense(cdev, lcirb))
177		return IO_RUNNING;
178	/* Check for halt/clear interrupt. */
179	if (scsw->fctl & (SCSW_FCTL_HALT_FUNC | SCSW_FCTL_CLEAR_FUNC))
180		return IO_KILLED;
181	/* Check for path error. */
182	if (scsw->cc == 3 || scsw->pno)
183		return IO_PATH_ERROR;
184	/* Handle BASIC SENSE data. */
185	if (irb->esw.esw0.erw.cons) {
186		CIO_TRACE_EVENT(2, "sensedata");
187		CIO_HEX_EVENT(2, &cdev->private->dev_id,
188			      sizeof(struct ccw_dev_id));
189		CIO_HEX_EVENT(2, &cdev->private->irb.ecw, SENSE_MAX_COUNT);
190		/* Check for command reject. */
191		if (irb->ecw[0] & SNS0_CMD_REJECT)
192			return IO_REJECTED;
193		/* Ask the driver what to do */
194		if (cdev->drv && cdev->drv->uc_handler) {
195			todo = cdev->drv->uc_handler(cdev, lcirb);
196			CIO_TRACE_EVENT(2, "uc_response");
197			CIO_HEX_EVENT(2, &todo, sizeof(todo));
198			switch (todo) {
199			case UC_TODO_RETRY:
200				return IO_STATUS_ERROR;
201			case UC_TODO_RETRY_ON_NEW_PATH:
202				return IO_PATH_ERROR;
203			case UC_TODO_STOP:
204				return IO_REJECTED;
205			default:
206				return IO_STATUS_ERROR;
207			}
208		}
209		/* Assume that unexpected SENSE data implies an error. */
210		return IO_STATUS_ERROR;
211	}
212	/* Check for channel errors. */
213	if (scsw->cstat != 0)
214		return IO_STATUS_ERROR;
215	/* Check for device errors. */
216	if (scsw->dstat & ~(DEV_STAT_CHN_END | DEV_STAT_DEV_END))
217		return IO_STATUS_ERROR;
218	/* Check for final state. */
219	if (!(scsw->dstat & DEV_STAT_DEV_END))
220		return IO_RUNNING;
221	/* Check for other improper status. */
222	if (scsw->cc == 1 && (scsw->stctl & SCSW_STCTL_ALERT_STATUS))
223		return IO_STATUS_ERROR;
224	return IO_DONE;
225}
226
227/*
228 * Log ccw request status.
229 */
230static void ccwreq_log_status(struct ccw_device *cdev, enum io_status status)
231{
232	struct ccw_request *req = &cdev->private->req;
233	struct {
234		struct ccw_dev_id dev_id;
235		u16 retries;
236		u8 lpm;
237		u8 status;
238	}  __attribute__ ((packed)) data;
239	data.dev_id	= cdev->private->dev_id;
240	data.retries	= req->retries;
241	data.lpm	= (u8) req->mask;
242	data.status	= (u8) status;
243	CIO_TRACE_EVENT(2, "reqstat");
244	CIO_HEX_EVENT(2, &data, sizeof(data));
245}
246
247/**
248 * ccw_request_handler - interrupt handler for I/O request procedure.
249 * @cdev: ccw device
250 *
251 * Handle interrupt during I/O request procedure.
252 */
253void ccw_request_handler(struct ccw_device *cdev)
254{
255	struct irb *irb = &__get_cpu_var(cio_irb);
256	struct ccw_request *req = &cdev->private->req;
257	enum io_status status;
258	int rc = -EOPNOTSUPP;
259
260	/* Check status of I/O request. */
261	status = ccwreq_status(cdev, irb);
262	if (req->filter)
263		status = req->filter(cdev, req->data, irb, status);
264	if (status != IO_RUNNING)
265		ccw_device_set_timeout(cdev, 0);
266	if (status != IO_DONE && status != IO_RUNNING)
267		ccwreq_log_status(cdev, status);
268	switch (status) {
269	case IO_DONE:
270		break;
271	case IO_RUNNING:
272		return;
273	case IO_REJECTED:
274		goto err;
275	case IO_PATH_ERROR:
276		goto out_next_path;
277	case IO_STATUS_ERROR:
278		goto out_restart;
279	case IO_KILLED:
280		/* Check if request was cancelled on purpose. */
281		if (req->cancel) {
282			rc = -EIO;
283			goto err;
284		}
285		goto out_restart;
286	}
287	/* Check back with request initiator. */
288	if (!req->check)
289		goto out;
290	switch (req->check(cdev, req->data)) {
291	case 0:
292		break;
293	case -EAGAIN:
294		goto out_restart;
295	case -EACCES:
296		goto out_next_path;
297	default:
298		goto err;
299	}
300out:
301	ccwreq_stop(cdev, 0);
302	return;
303
304out_next_path:
305	/* Try next path and restart I/O. */
306	if (!ccwreq_next_path(cdev)) {
307		rc = -EACCES;
308		goto err;
309	}
310out_restart:
311	/* Restart. */
312	ccwreq_do(cdev);
313	return;
314err:
315	ccwreq_stop(cdev, rc);
316}
317
318
319/**
320 * ccw_request_timeout - timeout handler for I/O request procedure
321 * @cdev: ccw device
322 *
323 * Handle timeout during I/O request procedure.
324 */
325void ccw_request_timeout(struct ccw_device *cdev)
326{
327	struct subchannel *sch = to_subchannel(cdev->dev.parent);
328	struct ccw_request *req = &cdev->private->req;
329	int rc = -ENODEV, chp;
330
331	if (cio_update_schib(sch))
332		goto err;
333
334	for (chp = 0; chp < 8; chp++) {
335		if ((0x80 >> chp) & sch->schib.pmcw.lpum)
336			pr_warning("%s: No interrupt was received within %lus "
337				   "(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
354err:
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 */
364void ccw_request_notoper(struct ccw_device *cdev)
365{
366	ccwreq_stop(cdev, -ENODEV);
367}
368