Make sure the bus is idle before starting a transfer.

ok deraadt@

diff --git a/sys/dev/fdt/ociic.c b/sys/dev/fdt/ociic.c
index 736514d..a184acf 100644 (file)
--- a/sys/dev/fdt/ociic.c
+++ b/sys/dev/fdt/ociic.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: ociic.c,v 1.1 2021/06/16 12:37:24 kettenis Exp $      */
+/*     $OpenBSD: ociic.c,v 1.2 2021/06/23 13:39:12 kettenis Exp $      */
 /*
  * Copyright (c) 2021 Mark Kettenis <kettenis@openbsd.org>
  *
@@ -188,6 +188,26 @@ ociic_release_bus(void *cookie, int flags)
        ociic_clr(sc, I2C_CTR, I2C_CTR_EN);
 }
 
+int
+ociic_unbusy(struct ociic_softc *sc)
+{
+       uint8_t stat;
+       int timo;
+
+       for (timo = 50000; timo > 0; timo--) {
+               stat = ociic_read(sc, I2C_SR);
+               if ((stat & I2C_SR_BUSY) == 0)
+                       break;
+               delay(10);
+       }
+       if (timo == 0) {
+               ociic_write(sc, I2C_CR, I2C_CR_STO);
+               return ETIMEDOUT;
+       }
+
+       return 0;
+}
+
 int
 ociic_wait(struct ociic_softc *sc, int ack)
 {
@@ -226,6 +246,10 @@ ociic_exec(void *cookie, i2c_op_t op, i2c_addr_t addr, const void *cmd,
        struct ociic_softc *sc = cookie;
        int error, i;
 
+       error = ociic_unbusy(sc);
+       if (error)
+               return error;
+
        if (cmdlen > 0) {
                ociic_write(sc, I2C_TXR, addr << 1);
                ociic_write(sc, I2C_CR, I2C_CR_STA | I2C_CR_WR);