soc: apple: Add driver for Apple PMGR misc controls

Apple SoCs have PMGR blocks that control a bunch of power-related
features. Besides the existing device power state controls (which are
very uniform and handled by apple-pmgr-pwrstate), we also need to manage
more random registers such as SoC-wide fabric and memory controller
power states, which have a different interface.

Add a driver for these kitchen sink controls. Right now it implements
fabric and memory controller power state switching on system
standby/s2idle, which saves about 1W of power or so on t60xx platforms.

Signed-off-by: Hector Martin <marcan@marcan.st>

Author: marcan

drivers/soc/apple/Kconfig

@@ -4,6 +4,15 @@ if ARCH_APPLE || COMPILE_TEST
 
 menu "Apple SoC drivers"
 
+config APPLE_PMGR_MISC
+	bool "Apple SoC PMGR miscellaneous support"
+	depends on PM
+	default ARCH_APPLE
+	help
+	  The PMGR block in Apple SoCs provides high-level power state
+	  controls for SoC devices. This driver manages miscellaneous
+	  power controls.
+
 config APPLE_MAILBOX
 	tristate "Apple SoC mailboxes"
 	depends on PM

drivers/soc/apple/Makefile

@@ -1,5 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 
+obj-$(CONFIG_APPLE_PMGR_MISC)	+= apple-pmgr-misc.o
+
 obj-$(CONFIG_APPLE_MAILBOX) += apple-mailbox.o
 apple-mailbox-y = mailbox.o
 

drivers/soc/apple/apple-pmgr-misc.c

@@ -0,0 +1,158 @@
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+/*
+ * Apple SoC PMGR device power state driver
+ *
+ * Copyright The Asahi Linux Contributors
+ */
+
+#include <linux/bitops.h>
+#include <linux/bitfield.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/module.h>
+
+#define APPLE_CLKGEN_PSTATE 0
+#define APPLE_CLKGEN_PSTATE_DESIRED GENMASK(3, 0)
+
+#define SYS_DEV_PSTATE_SUSPEND 1
+
+enum sys_device {
+	DEV_FABRIC,
+	DEV_DCS,
+	DEV_MAX,
+};
+
+struct apple_pmgr_sys_device {
+	void __iomem *base;
+	u32 active_state;
+	u32 suspend_state;
+};
+
+struct apple_pmgr_misc {
+	struct device *dev;
+	struct apple_pmgr_sys_device devices[DEV_MAX];
+};
+
+static void apple_pmgr_sys_dev_set_pstate(struct apple_pmgr_misc *misc,
+					  enum sys_device dev, bool active)
+{
+	u32 pstate;
+	u32 val;
+
+	if (!misc->devices[dev].base)
+		return;
+
+	if (active)
+		pstate = misc->devices[dev].active_state;
+	else
+		pstate = misc->devices[dev].suspend_state;
+
+	printk("set %d ps to pstate %d\n", dev, pstate);
+
+	val = readl_relaxed(misc->devices[dev].base + APPLE_CLKGEN_PSTATE);
+	val &= ~APPLE_CLKGEN_PSTATE_DESIRED;
+	val |= FIELD_PREP(APPLE_CLKGEN_PSTATE_DESIRED, pstate);
+	writel_relaxed(val, misc->devices[dev].base);
+}
+
+static int __maybe_unused apple_pmgr_misc_suspend_noirq(struct device *dev)
+{
+	struct apple_pmgr_misc *misc = dev_get_drvdata(dev);
+	int i;
+
+	for (i = 0; i < DEV_MAX; i++)
+		apple_pmgr_sys_dev_set_pstate(misc, i, false);
+
+	return 0;
+}
+
+static int __maybe_unused apple_pmgr_misc_resume_noirq(struct device *dev)
+{
+	struct apple_pmgr_misc *misc = dev_get_drvdata(dev);
+	int i;
+
+	for (i = 0; i < DEV_MAX; i++)
+		apple_pmgr_sys_dev_set_pstate(misc, i, true);
+
+	return 0;
+}
+
+static bool apple_pmgr_init_device(struct apple_pmgr_misc *misc,
+				   enum sys_device dev, const char *device_name)
+{
+	void __iomem *base;
+	char name[32];
+	u32 val;
+
+	snprintf(name, sizeof(name), "%s-ps", device_name);
+
+	base = devm_platform_ioremap_resource_byname(
+		to_platform_device(misc->dev), name);
+	if (!base)
+		return false;
+
+	val = readl_relaxed(base + APPLE_CLKGEN_PSTATE);
+
+	misc->devices[dev].base = base;
+	misc->devices[dev].active_state =
+		FIELD_GET(APPLE_CLKGEN_PSTATE_DESIRED, val);
+	misc->devices[dev].suspend_state = SYS_DEV_PSTATE_SUSPEND;
+
+	snprintf(name, sizeof(name), "apple,%s-min-ps", device_name);
+	of_property_read_u32(misc->dev->of_node, name,
+			     &misc->devices[dev].suspend_state);
+
+	return true;
+}
+
+static int apple_pmgr_misc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct apple_pmgr_misc *misc;
+	int ret = -ENODEV;
+
+	misc = devm_kzalloc(dev, sizeof(*misc), GFP_KERNEL);
+	if (!misc)
+		return -ENOMEM;
+
+	misc->dev = dev;
+
+	if (apple_pmgr_init_device(misc, DEV_FABRIC, "fabric"))
+		ret = 0;
+
+	if (apple_pmgr_init_device(misc, DEV_DCS, "dcs"))
+		ret = 0;
+
+	platform_set_drvdata(pdev, misc);
+
+	return ret;
+}
+
+static const struct of_device_id apple_pmgr_misc_of_match[] = {
+	{ .compatible = "apple,t6000-pmgr-misc" },
+	{}
+};
+
+MODULE_DEVICE_TABLE(of, apple_pmgr_misc_of_match);
+
+static const struct dev_pm_ops apple_pmgr_misc_pm_ops = {
+	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(apple_pmgr_misc_suspend_noirq,
+				      apple_pmgr_misc_resume_noirq)
+};
+
+static struct platform_driver apple_pmgr_misc_driver = {
+	.probe = apple_pmgr_misc_probe,
+	.driver = {
+		.name = "apple-pmgr-misc",
+		.of_match_table = apple_pmgr_misc_of_match,
+		.pm = pm_ptr(&apple_pmgr_misc_pm_ops),
+	},
+};
+
+MODULE_AUTHOR("Hector Martin <marcan@marcan.st>");
+MODULE_DESCRIPTION("PMGR misc driver for Apple SoCs");
+MODULE_LICENSE("GPL v2");
+
+module_platform_driver(apple_pmgr_misc_driver);