[PATCH v2 7/9] power: domain: apple: Add reset support

[Mark Kettenis <kettenis@openbsd.org>]

The power management controller found on Apple SoCs als provides
a way to reset all devices within a power domain. This is needed
to cleanly shutdown the NVMe controller before we hand over
control to the OS.

Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested on: Macbook Air M1
Tested-by: Simon Glass <sjg@chromium.org>
---
 arch/arm/Kconfig                  |  1 +
 drivers/power/domain/apple-pmgr.c | 73 ++++++++++++++++++++++++++++++-
 2 files changed, 73 insertions(+), 1 deletion(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index ecacd6860b..14c83ea19e 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -935,6 +935,7 @@ config ARCH_APPLE
 	select DM_GPIO
 	select DM_KEYBOARD
 	select DM_MAILBOX
+	select DM_RESET
 	select DM_SERIAL
 	select DM_USB
 	select DM_VIDEO
diff --git a/drivers/power/domain/apple-pmgr.c b/drivers/power/domain/apple-pmgr.c
index d25f136b9d..4d06e76ff5 100644
--- a/drivers/power/domain/apple-pmgr.c
+++ b/drivers/power/domain/apple-pmgr.c
@@ -6,14 +6,22 @@
 #include <common.h>
 #include <asm/io.h>
 #include <dm.h>
+#include <dm/device-internal.h>
 #include <linux/err.h>
 #include <linux/bitfield.h>
 #include <power-domain-uclass.h>
+#include <reset-uclass.h>
 #include <regmap.h>
 #include <syscon.h>
 
-#define APPLE_PMGR_PS_TARGET	GENMASK(3, 0)
+#define APPLE_PMGR_RESET	BIT(31)
+#define APPLE_PMGR_DEV_DISABLE	BIT(10)
+#define APPLE_PMGR_WAS_CLKGATED	BIT(9)
+#define APPLE_PMGR_WAS_PWRGATED BIT(8)
 #define APPLE_PMGR_PS_ACTUAL	GENMASK(7, 4)
+#define APPLE_PMGR_PS_TARGET	GENMASK(3, 0)
+
+#define APPLE_PMGR_FLAGS	(APPLE_PMGR_WAS_CLKGATED | APPLE_PMGR_WAS_PWRGATED)
 
 #define APPLE_PMGR_PS_ACTIVE	0xf
 #define APPLE_PMGR_PS_PWRGATE	0x0
@@ -25,6 +33,65 @@ struct apple_pmgr_priv {
 	u32 offset;		/* offset within regmap for this domain */
 };
 
+static int apple_reset_of_xlate(struct reset_ctl *reset_ctl,
+				struct ofnode_phandle_args *args)
+{
+	if (args->args_count != 0)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int apple_reset_request(struct reset_ctl *reset_ctl)
+{
+	return 0;
+}
+
+static int apple_reset_free(struct reset_ctl *reset_ctl)
+{
+	return 0;
+}
+
+static int apple_reset_assert(struct reset_ctl *reset_ctl)
+{
+	struct apple_pmgr_priv *priv = dev_get_priv(reset_ctl->dev->parent);
+
+	regmap_update_bits(priv->regmap, priv->offset,
+			   APPLE_PMGR_FLAGS | APPLE_PMGR_DEV_DISABLE,
+			   APPLE_PMGR_DEV_DISABLE);
+	regmap_update_bits(priv->regmap, priv->offset,
+			   APPLE_PMGR_FLAGS | APPLE_PMGR_RESET,
+			   APPLE_PMGR_RESET);
+
+	return 0;
+}
+
+static int apple_reset_deassert(struct reset_ctl *reset_ctl)
+{
+	struct apple_pmgr_priv *priv = dev_get_priv(reset_ctl->dev->parent);
+
+	regmap_update_bits(priv->regmap, priv->offset,
+			   APPLE_PMGR_FLAGS | APPLE_PMGR_RESET, 0);
+	regmap_update_bits(priv->regmap, priv->offset,
+			   APPLE_PMGR_FLAGS | APPLE_PMGR_DEV_DISABLE, 0);
+
+	return 0;
+}
+
+struct reset_ops apple_reset_ops = {
+	.of_xlate = apple_reset_of_xlate,
+	.request = apple_reset_request,
+	.rfree = apple_reset_free,
+	.rst_assert = apple_reset_assert,
+	.rst_deassert = apple_reset_deassert,
+};
+
+static struct driver apple_reset_driver = {
+	.name = "apple_reset",
+	.id = UCLASS_RESET,
+	.ops = &apple_reset_ops,
+};
+
 static int apple_pmgr_request(struct power_domain *power_domain)
 {
 	return 0;
@@ -78,6 +145,7 @@ static const struct udevice_id apple_pmgr_ids[] = {
 static int apple_pmgr_probe(struct udevice *dev)
 {
 	struct apple_pmgr_priv *priv = dev_get_priv(dev);
+	struct udevice *child;
 	int ret;
 
 	ret = dev_power_domain_on(dev);
@@ -92,6 +160,9 @@ static int apple_pmgr_probe(struct udevice *dev)
 	if (ret < 0)
 		return ret;
 
+	device_bind(dev, &apple_reset_driver, "apple_reset", NULL,
+		    dev_ofnode(dev), &child);
+
 	return 0;
 }
 
-- 
2.34.1