[src/trunk]: src/sys/dev/i2c Improve diagnostic messages:

[thorpej <thorpej%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/d8961cc2d15a
branches:  trunk
changeset: 467084:d8961cc2d15a
user:      thorpej <thorpej%NetBSD.org@localhost>
date:      Mon Jan 13 00:09:28 2020 +0000

description:
Improve diagnostic messages:
- Pass an additional argument to gttwsi_wait() to indicate what's
  going on, and report that, along with the error code from
  cv_timedwait(), if a timeout occurs.
- In gttwsi_send_stop(), if we don't get the expected NRS status,
  report which status we *did* get when a timeout occurs.

diffstat:

 sys/dev/i2c/gttwsi_core.c |  55 +++++++++++++++++++++++++++++-----------------
 1 files changed, 35 insertions(+), 20 deletions(-)

diffs (160 lines):

diff -r db1724f6aa50 -r d8961cc2d15a sys/dev/i2c/gttwsi_core.c
--- a/sys/dev/i2c/gttwsi_core.c Sun Jan 12 23:22:12 2020 +0000
+++ b/sys/dev/i2c/gttwsi_core.c Mon Jan 13 00:09:28 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: gttwsi_core.c,v 1.12 2020/01/12 17:48:42 thorpej Exp $ */
+/*     $NetBSD: gttwsi_core.c,v 1.13 2020/01/13 00:09:28 thorpej Exp $ */
 /*
  * Copyright (c) 2008 Eiji Kawauchi.
  * All rights reserved.
@@ -66,7 +66,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: gttwsi_core.c,v 1.12 2020/01/12 17:48:42 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: gttwsi_core.c,v 1.13 2020/01/13 00:09:28 thorpej Exp $");
 #include "locators.h"
 
 #include <sys/param.h>
@@ -90,7 +90,7 @@
 static int     gttwsi_write_byte(void *v, uint8_t val, int flags);
 
 static int     gttwsi_wait(struct gttwsi_softc *, uint32_t, uint32_t,
-                           uint32_t, int);
+                           uint32_t, int, const char *);
 
 uint32_t
 gttwsi_read_4(struct gttwsi_softc *sc, uint32_t reg)
@@ -195,7 +195,7 @@
        else
                expect = STAT_SCT;
        sc->sc_started = true;
-       return gttwsi_wait(sc, CONTROL_START, expect, 0, flags);
+       return gttwsi_wait(sc, CONTROL_START, expect, 0, flags, "send-start");
 }
 
 static int
@@ -203,7 +203,7 @@
 {
        struct gttwsi_softc *sc = v;
        int retry = TWSI_RETRY_COUNT;
-       uint32_t control;
+       uint32_t control, status;
 
        sc->sc_started = false;
 
@@ -213,14 +213,15 @@
                control |= CONTROL_IFLG;
        gttwsi_write_4(sc, TWSI_CONTROL, control);
        while (retry > 0) {
-               if (gttwsi_read_4(sc, TWSI_STATUS) == STAT_NRS)
+               if ((status = gttwsi_read_4(sc, TWSI_STATUS)) == STAT_NRS)
                        return 0;
                retry--;
                DELAY(TWSI_STAT_DELAY);
        }
 
-       aprint_error_dev(sc->sc_dev, "send STOP failed\n");
-       return -1;
+       aprint_error_dev(sc->sc_dev, "send STOP failed, status=0x%02x\n",
+                        status);
+       return EWOULDBLOCK;
 }
 
 static int
@@ -254,7 +255,7 @@
                 */
                data |= 0xf0 | ((addr & 0x300) >> 7);
                gttwsi_write_4(sc, TWSI_DATA, data);
-               error = gttwsi_wait(sc, 0, expect, alt, flags);
+               error = gttwsi_wait(sc, 0, expect, alt, flags, "send-addr-10");
                if (error)
                        return error;
                /*
@@ -273,7 +274,7 @@
                data |= (addr << 1);
 
        gttwsi_write_4(sc, TWSI_DATA, data);
-       return gttwsi_wait(sc, 0, expect, alt, flags);
+       return gttwsi_wait(sc, 0, expect, alt, flags, "send-addr");
 }
 
 static int
@@ -282,10 +283,13 @@
        struct gttwsi_softc *sc = v;
        int error;
 
-       if (flags & I2C_F_LAST)
-               error = gttwsi_wait(sc, 0, STAT_MRRD_ANT, 0, flags);
-       else
-               error = gttwsi_wait(sc, CONTROL_ACK, STAT_MRRD_AT, 0, flags);
+       if (flags & I2C_F_LAST) {
+               error = gttwsi_wait(sc, 0, STAT_MRRD_ANT, 0, flags,
+                                   "read-last-byte");
+       } else {
+               error = gttwsi_wait(sc, CONTROL_ACK, STAT_MRRD_AT, 0, flags,
+                                   "read-byte");
+       }
        if (!error)
                *valp = gttwsi_read_4(sc, TWSI_DATA);
        if ((flags & (I2C_F_LAST | I2C_F_STOP)) == (I2C_F_LAST | I2C_F_STOP))
@@ -300,7 +304,7 @@
        int error;
 
        gttwsi_write_4(sc, TWSI_DATA, val);
-       error = gttwsi_wait(sc, 0, STAT_MTDB_AR, 0, flags);
+       error = gttwsi_wait(sc, 0, STAT_MTDB_AR, 0, flags, "write-byte");
        if (flags & I2C_F_STOP)
                gttwsi_send_stop(sc, flags);
        return error;
@@ -308,7 +312,7 @@
 
 static int
 gttwsi_wait(struct gttwsi_softc *sc, uint32_t control, uint32_t expect,
-           uint32_t alt, int flags)
+           uint32_t alt, int flags, const char *what)
 {
        uint32_t status;
        int timo, error = 0;
@@ -328,8 +332,9 @@
                        break;
                if (!(flags & I2C_F_POLL)) {
                        error = cv_timedwait(&sc->sc_cv, &sc->sc_mtx, hz);
-                       if (error)
+                       if (error) {
                                break;
+                       }
                } else {
                        DELAY(TWSI_RETRY_DELAY);
                        if (timo++ > 1000000)   /* 1sec */
@@ -337,9 +342,19 @@
                }
        }
        if ((control & CONTROL_IFLG) == 0) {
+               /*
+                * error is set by the cv_timedwait() call above in the
+                * non-polled case.
+                */
+               if (flags & I2C_F_POLL) {
+                       error = EWOULDBLOCK;
+               } else {
+                       KASSERT(error != 0);
+               }
                aprint_error_dev(sc->sc_dev,
-                   "gttwsi_wait(): timeout, control=0x%x\n", control);
-               error = EWOULDBLOCK;
+                   "gttwsi_wait(): %s timeout%s, control=0x%x, error=%d\n",
+                   what, (flags & I2C_F_POLL) ? " (polled)" : "",
+                   control, error);
                goto end;
        }
        status = gttwsi_read_4(sc, TWSI_STATUS);
@@ -356,7 +371,7 @@
                            expect);
                error = EIO;
        }
-end:
+ end:
        mutex_exit(&sc->sc_mtx);
        return error;
 }