From: deraadt <deraadt@openbsd.org>
Date: Sat, 17 Aug 2024 02:28:45 +0000 (+0000)
Subject: The dwiic_init() routine is used at startup to read various chip
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=c6b110bc30baf518b2ce4191778de57b3cd04075;p=openbsd

The dwiic_init() routine is used at startup to read various chip
registers, make some decisions, and then program other registers.  After
a resume, it is pointless, and potentially incorrect to read such registers
again, which a BIOS or something may not have initialized, and we are
better off using the remembered soft-state to init cleanly.  So craft a
custom block of chip restoration, and do it while the chip is stopped hard.
ok kettenis mlarkin
---

diff --git a/sys/dev/ic/dwiic.c b/sys/dev/ic/dwiic.c
index ba425226ab4..2ca0dc3ffc9 100644
--- a/sys/dev/ic/dwiic.c
+++ b/sys/dev/ic/dwiic.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: dwiic.c,v 1.19 2024/08/17 02:24:03 deraadt Exp $ */
+/* $OpenBSD: dwiic.c,v 1.20 2024/08/17 02:28:45 deraadt Exp $ */
 /*
  * Synopsys DesignWare I2C controller
  *
@@ -46,7 +46,30 @@ dwiic_activate(struct device *self, int act)
 		dwiic_read(sc, DW_IC_CLR_INTR);
 		break;
 	case DVACT_RESUME:
-		dwiic_init(sc);
+		/* if it became enabled for some reason, force it down */
+		dwiic_enable(sc, 0);
+
+		dwiic_write(sc, DW_IC_INTR_MASK, 0);
+		dwiic_read(sc, DW_IC_CLR_INTR);
+
+		/* write standard-mode SCL timing parameters */
+		dwiic_write(sc, DW_IC_SS_SCL_HCNT, sc->ss_hcnt);
+		dwiic_write(sc, DW_IC_SS_SCL_LCNT, sc->ss_lcnt);
+
+		/* and fast-mode SCL timing parameters */
+		dwiic_write(sc, DW_IC_FS_SCL_HCNT, sc->fs_hcnt);
+		dwiic_write(sc, DW_IC_FS_SCL_LCNT, sc->fs_lcnt);
+
+		/* SDA hold time */
+		dwiic_write(sc, DW_IC_SDA_HOLD, sc->sda_hold_time);
+
+		dwiic_write(sc, DW_IC_TX_TL, sc->tx_fifo_depth / 2);
+		dwiic_write(sc, DW_IC_RX_TL, 0);
+
+		/* configure as i2c master with fast speed */
+		sc->master_cfg = DW_IC_CON_MASTER | DW_IC_CON_SLAVE_DISABLE |
+		    DW_IC_CON_RESTART_EN | DW_IC_CON_SPEED_FAST;
+		dwiic_write(sc, DW_IC_CON, sc->master_cfg);
 		rv = config_activate_children(self, act);
 		break;
 	default: