[PATCH 3/3] power: domain: Add Apple pmgr driver

[Mark Kettenis <kettenis@openbsd.org>]

This driver supports power domains for the power management
controller found on Apple SoCs.

Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
---
 arch/arm/Kconfig                  |   3 +
 drivers/power/domain/Kconfig      |   8 +++
 drivers/power/domain/Makefile     |   1 +
 drivers/power/domain/apple-pmgr.c | 113 ++++++++++++++++++++++++++++++
 4 files changed, 125 insertions(+)
 create mode 100644 drivers/power/domain/apple-pmgr.c

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 0634e0c5ae..0b320385a6 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -939,6 +939,9 @@ config ARCH_APPLE
 	select OF_BOARD
 	select PINCTRL
 	select POSITION_INDEPENDENT
+	select POWER_DOMAIN
+	select REGMAP
+	select SYSCON
 	select SYSRESET
 	select SYSRESET_WATCHDOG
 	select SYSRESET_WATCHDOG_AUTO
diff --git a/drivers/power/domain/Kconfig b/drivers/power/domain/Kconfig
index 99b3f9ae71..6ef7a3b3a7 100644
--- a/drivers/power/domain/Kconfig
+++ b/drivers/power/domain/Kconfig
@@ -9,6 +9,14 @@ config POWER_DOMAIN
 	  domains). This may be used to save power. This API provides the
 	  means to control such power management hardware.
 
+config APPLE_PMGR_POWER_DOMAIN
+	bool "Enable the Apple PMGR power domain driver"
+	depends on POWER_DOMAIN
+	default y if ARCH_APPLE
+	help
+	  Enable support for manipulating the Apple M1 power domains via
+	  MMIO mapped registers.
+
 config BCM6328_POWER_DOMAIN
 	bool "Enable the BCM6328 power domain driver"
 	depends on POWER_DOMAIN && ARCH_BMIPS
diff --git a/drivers/power/domain/Makefile b/drivers/power/domain/Makefile
index 3d1e5f073c..530ae35671 100644
--- a/drivers/power/domain/Makefile
+++ b/drivers/power/domain/Makefile
@@ -4,6 +4,7 @@
 #
 
 obj-$(CONFIG_$(SPL_)POWER_DOMAIN) += power-domain-uclass.o
+obj-$(CONFIG_APPLE_PMGR_POWER_DOMAIN) += apple-pmgr.o
 obj-$(CONFIG_BCM6328_POWER_DOMAIN) += bcm6328-power-domain.o
 obj-$(CONFIG_IMX8_POWER_DOMAIN) += imx8-power-domain-legacy.o imx8-power-domain.o
 obj-$(CONFIG_IMX8M_POWER_DOMAIN) += imx8m-power-domain.o
diff --git a/drivers/power/domain/apple-pmgr.c b/drivers/power/domain/apple-pmgr.c
new file mode 100644
index 0000000000..08a30c8ebf
--- /dev/null
+++ b/drivers/power/domain/apple-pmgr.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2021 Mark Kettenis <kettenis@openbsd.org>
+ */
+
+#include <common.h>
+#include <asm/io.h>
+#include <dm.h>
+#include <linux/err.h>
+#include <linux/bitfield.h>
+#include <power-domain-uclass.h>
+#include <regmap.h>
+#include <syscon.h>
+
+#define APPLE_PMGR_PS_TARGET	GENMASK(3, 0)
+#define APPLE_PMGR_PS_ACTUAL	GENMASK(7, 4)
+
+#define APPLE_PMGR_PS_ACTIVE	0xf
+#define APPLE_PMGR_PS_PWRGATE	0x0
+
+#define APPLE_PMGR_PS_SET_TIMEOUT	100
+
+struct apple_pmgr_priv {
+	struct regmap *regmap;
+	u32 offset;
+};
+
+static int apple_pmgr_request(struct power_domain *power_domain)
+{
+	return 0;
+}
+
+static int apple_pmgr_rfree(struct power_domain *power_domain)
+{
+	return 0;
+}
+
+static int apple_pmgr_ps_set(struct power_domain *power_domain, u32 pstate)
+{
+	struct apple_pmgr_priv *priv = dev_get_priv(power_domain->dev);
+	uint reg;
+
+	regmap_update_bits(priv->regmap, priv->offset, APPLE_PMGR_PS_TARGET,
+			   FIELD_PREP(APPLE_PMGR_PS_TARGET, pstate));
+
+	return regmap_read_poll_timeout(
+		priv->regmap, priv->offset, reg,
+		(FIELD_GET(APPLE_PMGR_PS_ACTUAL, reg) == pstate), 1,
+		APPLE_PMGR_PS_SET_TIMEOUT);
+}
+
+static int apple_pmgr_on(struct power_domain *power_domain)
+{
+	return apple_pmgr_ps_set(power_domain, APPLE_PMGR_PS_ACTIVE);
+}
+
+static int apple_pmgr_off(struct power_domain *power_domain)
+{
+	return 0;
+}
+
+static int apple_pmgr_of_xlate(struct power_domain *power_domain,
+			       struct ofnode_phandle_args *args)
+{
+	if (args->args_count != 0) {
+		debug("Invalid args_count: %d\n", args->args_count);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static const struct udevice_id apple_pmgr_ids[] = {
+	{ .compatible = "apple,pmgr-pwrstate" },
+	{ /* sentinel */ }
+};
+
+static int apple_pmgr_probe(struct udevice *dev)
+{
+	struct apple_pmgr_priv *priv = dev_get_priv(dev);
+	int ret;
+
+	ret = dev_power_domain_on(dev);
+	if (ret)
+		return ret;
+
+	priv->regmap = syscon_get_regmap(dev->parent);
+	if (IS_ERR(priv->regmap))
+		return PTR_ERR(priv->regmap);
+
+	ret = dev_read_u32(dev, "reg", &priv->offset);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+struct power_domain_ops apple_pmgr_ops = {
+	.request = apple_pmgr_request,
+	.rfree = apple_pmgr_rfree,
+	.on = apple_pmgr_on,
+	.off = apple_pmgr_off,
+	.of_xlate = apple_pmgr_of_xlate,
+};
+
+U_BOOT_DRIVER(apple_pmgr) = {
+	.name = "apple_pmgr",
+	.id = UCLASS_POWER_DOMAIN,
+	.of_match = apple_pmgr_ids,
+	.ops = &apple_pmgr_ops,
+	.probe = apple_pmgr_probe,
+	.priv_auto = sizeof(struct apple_pmgr_priv),
+};
-- 
2.34.1