[src/trunk]: src/sys/dev/i2c Add wait for stop condition.

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

details:   https://anonhg.NetBSD.org/src/rev/69ec7a1b542c
branches:  trunk
changeset: 461518:69ec7a1b542c
user:      hkenken <hkenken%NetBSD.org@localhost>
date:      Fri Nov 29 12:42:53 2019 +0000

description:
Add wait for stop condition.

diffstat:

 sys/dev/i2c/motoi2c.c |  43 +++++++++++++++++++++++++++----------------
 1 files changed, 27 insertions(+), 16 deletions(-)

diffs (101 lines):

diff -r e855542215da -r 69ec7a1b542c sys/dev/i2c/motoi2c.c
--- a/sys/dev/i2c/motoi2c.c     Fri Nov 29 12:04:32 2019 +0000
+++ b/sys/dev/i2c/motoi2c.c     Fri Nov 29 12:42:53 2019 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: motoi2c.c,v 1.5 2019/08/05 12:21:00 hkenken Exp $ */
+/* $NetBSD: motoi2c.c,v 1.6 2019/11/29 12:42:53 hkenken Exp $ */
 
 /*-
  * Copyright (c) 2007, 2010 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: motoi2c.c,v 1.5 2019/08/05 12:21:00 hkenken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: motoi2c.c,v 1.6 2019/11/29 12:42:53 hkenken Exp $");
 
 #if defined(__arm__) || defined(__aarch64__)
 #include "opt_fdt.h"
@@ -163,6 +163,24 @@
        mutex_exit(&sc->sc_buslock);
 }
 
+static int
+motoi2c_stop_wait(struct motoi2c_softc *sc)
+{
+       u_int timo;
+       int error = 0;
+
+       timo = 1000;
+       while ((I2C_READ(I2CSR) & SR_MBB) != 0 && --timo)
+               DELAY(1);
+
+       if (timo == 0) {
+               DPRINTF(("%s: timeout (sr=%#x)\n", __func__, I2C_READ(I2CSR)));
+               error = ETIMEDOUT;
+       }
+
+       return error;
+}
+
 /* busy waiting for byte data transfer completion */
 static int
 motoi2c_busy_wait(struct motoi2c_softc *sc, uint8_t cr)
@@ -224,15 +242,9 @@
 
        if ((cr & CR_MSTA) == 0 && (sr & SR_MBB) != 0) {
                /* wait for bus becoming available */
-               u_int timo = 100;
-               do {
-                       DELAY(10);
-               } while (--timo > 0 && ((sr = I2C_READ(I2CSR)) & SR_MBB) != 0);
-
-               if (timo == 0) {
-                       DPRINTF(("%s: bus is busy (%#x)\n", __func__, sr));
+               error = motoi2c_stop_wait(sc);
+               if (error)
                        return ETIMEDOUT;
-               }
        }
 
        /* reset interrupt and arbitration-lost flags (all others are RO) */
@@ -240,12 +252,10 @@
        sr = I2C_READ(I2CSR);
 
        /*
-        * Generate start (or restart) condition
+        * Generate start condition
         */
-       /* CR_RTSA is write-only and transitory */
-       uint8_t rsta = (cr & CR_MSTA ? CR_RSTA : 0);
        cr = CR_MEN | CR_MTX | CR_MSTA;
-       I2C_WRITE(I2CCR, cr | rsta);
+       I2C_WRITE(I2CCR, cr);
 
        DPRINTF(("%s: started: sr=%#x cr=%#x/%#x\n",
            __func__, I2C_READ(I2CSR), cr, I2C_READ(I2CCR)));
@@ -339,14 +349,14 @@
                                cr |= CR_TXAK;
                                I2C_WRITE(I2CCR, cr);
                        } else if (i == datalen - 1 && I2C_OP_STOP_P(op)) {
-                               cr = CR_MEN;
+                               cr = CR_MEN | CR_TXAK;
                                I2C_WRITE(I2CCR, cr);
                        }
                        *dataptr++ = I2C_READ(I2CDR);
                }
                if (datalen == 0) {
                        if (I2C_OP_STOP_P(op)) {
-                               cr = CR_MEN;
+                               cr = CR_MEN | CR_TXAK;
                                I2C_WRITE(I2CCR, cr);
                        }
                        (void)I2C_READ(I2CDR);  /* dummy read */
@@ -378,6 +388,7 @@
        if (error || (cr & CR_TXAK) || ((cr & CR_MSTA) && I2C_OP_STOP_P(op))) {
                cr = CR_MEN;
                I2C_WRITE(I2CCR, cr);
+               motoi2c_stop_wait(sc);
                DPRINTF(("%s: stopping: cr=%#x/%#x\n", __func__,
                    cr, I2C_READ(I2CCR)));
        }