From 75318f5b6c7e06955b2e416014aaf792834780e6 Mon Sep 17 00:00:00 2001
From: dlg <dlg@openbsd.org>
Date: Sun, 23 Apr 2023 00:33:02 +0000
Subject: [PATCH] add support for coordinating i2c bus access with iosf(4)

if the acpi node has a _SEM property, add wrappers around the i2c
bus acquire and release handlers to try and call the iosf provided
hardware semaphore ops. this means bus accesses can be coordinate
with other parts of the platform such as the punit.

this stops my Dell Wyse 3040 from locking up.

ok kettenis@ patrick@
---
 sys/dev/acpi/dwiic_acpi.c | 49 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 48 insertions(+), 1 deletion(-)

diff --git a/sys/dev/acpi/dwiic_acpi.c b/sys/dev/acpi/dwiic_acpi.c
index ad8b9776116a..acfe7b5327c6 100644
--- a/sys/dev/acpi/dwiic_acpi.c
+++ b/sys/dev/acpi/dwiic_acpi.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: dwiic_acpi.c,v 1.20 2022/08/31 15:14:01 kettenis Exp $ */
+/* $OpenBSD: dwiic_acpi.c,v 1.21 2023/04/23 00:33:02 dlg Exp $ */
 /*
  * Synopsys DesignWare I2C controller
  *
@@ -17,6 +17,8 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
+#include "iosf.h"
+
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/kernel.h>
@@ -28,6 +30,7 @@
 #include <dev/acpi/dsdt.h>
 
 #include <dev/ic/dwiicvar.h>
+#include <dev/ic/iosfvar.h>
 
 struct dwiic_crs {
 	int irq_int;
@@ -53,6 +56,11 @@ void		dwiic_acpi_power(struct dwiic_softc *, int);
 void		dwiic_acpi_bus_scan(struct device *,
 		    struct i2cbus_attach_args *, void *);
 
+#if NIOSF > 0
+int		dwiic_acpi_acquire_bus(void *, int);
+void		dwiic_acpi_release_bus(void *, int);
+#endif
+
 const struct cfattach dwiic_acpi_ca = {
 	sizeof(struct dwiic_softc),
 	dwiic_acpi_match,
@@ -103,6 +111,7 @@ dwiic_acpi_attach(struct device *parent, struct device *self, void *aux)
 	struct acpi_attach_args *aaa = aux;
 	struct aml_value res;
 	struct dwiic_crs crs;
+	uint64_t sem;
 
 	sc->sc_acpi = (struct acpi_softc *)parent;
 	sc->sc_devnode = aaa->aaa_node;
@@ -163,6 +172,13 @@ dwiic_acpi_attach(struct device *parent, struct device *self, void *aux)
 			printf(": can't establish interrupt");
 	}
 
+	if (aml_evalinteger(sc->sc_acpi, sc->sc_devnode,
+	    "_SEM", 0, NULL, &sem))
+		sem = 0;
+
+	if (sem)
+		printf(", sem");
+
 	printf("\n");
 
 	rw_init(&sc->sc_i2c_lock, "iiclk");
@@ -176,6 +192,13 @@ dwiic_acpi_attach(struct device *parent, struct device *self, void *aux)
 	sc->sc_i2c_tag.ic_intr_disestablish = dwiic_i2c_intr_disestablish;
 	sc->sc_i2c_tag.ic_intr_string = dwiic_i2c_intr_string;
 
+#if NIOSF > 0
+	if (sem) {
+		sc->sc_i2c_tag.ic_acquire_bus = dwiic_acpi_acquire_bus;
+		sc->sc_i2c_tag.ic_release_bus = dwiic_acpi_release_bus;
+	}
+#endif
+
 	bzero(&sc->sc_iba, sizeof(sc->sc_iba));
 	sc->sc_iba.iba_name = "iic";
 	sc->sc_iba.iba_tag = &sc->sc_i2c_tag;
@@ -547,3 +570,27 @@ dwiic_acpi_power(struct dwiic_softc *sc, int power)
 		dwiic_write(sc, 0x800, 1);
 	}
 }
+
+#if NIOSF > 0
+extern int	iosf_i2c_acquire(int);
+extern void	iosf_i2c_release(int);
+
+int
+dwiic_acpi_acquire_bus(void *cookie, int flags)
+{
+	int rv;
+
+	rv = dwiic_i2c_acquire_bus(cookie, flags);
+	if (rv != 0)
+		return (rv);
+
+	return (iosf_i2c_acquire(flags));
+}
+
+void
+dwiic_acpi_release_bus(void *cookie, int flags)
+{
+	iosf_i2c_release(flags);
+	dwiic_i2c_release_bus(cookie, flags);
+}
+#endif /* NIOSF > 0 */