Merge tag 'arm-soc-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc

Pull ARM SoC updates from Olof Johansson:
 "A few SoC (code) changes have queued up this cycle, mostly for minor
  changes and some refactoring and cleanup of legacy platforms. This
  branch also contains a few of the fixes that weren't sent in by the
  end of the release (all fairly minor).

   - Adding an additional maintainer for the TEE subsystem (Sumit Garg)

   - Quite a significant modernization of the IXP4xx platforms by Linus
     Walleij, revisiting with a new PCI host driver/binding, removing
     legacy mach/* include dependencies and moving platform
     detection/config to drivers/soc. Also some updates/cleanup of
     platform data.

   - Core power domain support for Tegra platforms, and some
     improvements in build test coverage by adding stubs for compile
     test targets.

   - A handful of updates to i.MX platforms, adding legacy (non-PSCI)
     SMP support on i.MX7D, SoC ID setup for i.MX50, removal of platform
     data and board fixups for iMX6/7.

  ... and a few smaller changes and fixes for Samsung, OMAP, Allwinner,
  Rockchip"

* tag 'arm-soc-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (53 commits)
  MAINTAINERS: Add myself as TEE subsystem reviewer
  ixp4xx: fix spelling mistake in Kconfig "Devce" -> "Device"
  hw_random: ixp4xx: Add OF support
  hw_random: ixp4xx: Add DT bindings
  hw_random: ixp4xx: Turn into a module
  hw_random: ixp4xx: Use SPDX license tag
  hw_random: ixp4xx: enable compile-testing
  pata: ixp4xx: split platform data to its own header
  soc: ixp4xx: move cpu detection to linux/soc/ixp4xx/cpu.h
  PCI: ixp4xx: Add a new driver for IXP4xx
  PCI: ixp4xx: Add device tree bindings for IXP4xx
  ARM/ixp4xx: Make NEED_MACH_IO_H optional
  ARM/ixp4xx: Move the virtual IObases
  MAINTAINERS: ARM/MStar/Sigmastar SoCs: Add a link to the MStar tree
  ARM: debug: add UART early console support for MSTAR SoCs
  ARM: dts: ux500: Fix LED probing
  ARM: imx: add smp support for imx7d
  ARM: imx6q: drop of_platform_default_populate() from init_machine
  arm64: dts: rockchip: Update RK3399 PCI host bridge window to 32-bit address memory
  soc/tegra: fuse: Fix Tegra234-only builds
  ...

1 files changed, 91 insertions, 2 deletions

diff --git a/drivers/soc/tegra/regulators-tegra30.c b/drivers/soc/tegra/regulators-tegra30.c
index 0e776b20f625..e74bbc9c7859 100644
--- a/drivers/soc/tegra/regulators-tegra30.c
+++ b/drivers/soc/tegra/regulators-tegra30.c
@@ -12,17 +12,22 @@
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/of.h>
+#include <linux/reboot.h>
 #include <linux/regulator/coupler.h>
 #include <linux/regulator/driver.h>
 #include <linux/regulator/machine.h>
 
 #include <soc/tegra/fuse.h>
+#include <soc/tegra/pmc.h>
 
 struct tegra_regulator_coupler {
 	struct regulator_coupler coupler;
 	struct regulator_dev *core_rdev;
 	struct regulator_dev *cpu_rdev;
-	int core_min_uV;
+	struct notifier_block reboot_notifier;
+	int core_min_uV, cpu_min_uV;
+	bool sys_reboot_mode_req;
+	bool sys_reboot_mode;
 };
 
 static inline struct tegra_regulator_coupler *
@@ -39,6 +44,21 @@ static int tegra30_core_limit(struct tegra_regulator_coupler *tegra,
 	int core_cur_uV;
 	int err;
 
+	/*
+	 * Tegra30 SoC has critical DVFS-capable devices that are
+	 * permanently-active or active at a boot time, like EMC
+	 * (DRAM controller) or Display controller for example.
+	 *
+	 * The voltage of a CORE SoC power domain shall not be dropped below
+	 * a minimum level, which is determined by device's clock rate.
+	 * This means that we can't fully allow CORE voltage scaling until
+	 * the state of all DVFS-critical CORE devices is synced.
+	 */
+	if (tegra_pmc_core_domain_state_synced() && !tegra->sys_reboot_mode) {
+		pr_info_once("voltage state synced\n");
+		return 0;
+	}
+
 	if (tegra->core_min_uV > 0)
 		return tegra->core_min_uV;
 
@@ -59,7 +79,7 @@ static int tegra30_core_limit(struct tegra_regulator_coupler *tegra,
 	 */
 	tegra->core_min_uV = core_max_uV;
 
-	pr_info("core minimum voltage limited to %duV\n", tegra->core_min_uV);
+	pr_info("core voltage initialized to %duV\n", tegra->core_min_uV);
 
 	return tegra->core_min_uV;
 }
@@ -172,6 +192,10 @@ static int tegra30_voltage_update(struct tegra_regulator_coupler *tegra,
 	if (cpu_uV < 0)
 		return cpu_uV;
 
+	/* store boot voltage level */
+	if (!tegra->cpu_min_uV)
+		tegra->cpu_min_uV = cpu_uV;
+
 	/*
 	 * CPU's regulator may not have any consumers, hence the voltage
 	 * must not be changed in that case because CPU simply won't
@@ -195,6 +219,10 @@ static int tegra30_voltage_update(struct tegra_regulator_coupler *tegra,
 	if (err)
 		return err;
 
+	/* restore boot voltage level */
+	if (tegra->sys_reboot_mode)
+		cpu_min_uV = max(cpu_min_uV, tegra->cpu_min_uV);
+
 	if (core_min_limited_uV > core_uV) {
 		pr_err("core voltage constraint violated: %d %d %d\n",
 		       core_uV, core_min_limited_uV, cpu_uV);
@@ -263,9 +291,56 @@ static int tegra30_regulator_balance_voltage(struct regulator_coupler *coupler,
 		return -EINVAL;
 	}
 
+	tegra->sys_reboot_mode = READ_ONCE(tegra->sys_reboot_mode_req);
+
 	return tegra30_voltage_update(tegra, cpu_rdev, core_rdev);
 }
 
+static int tegra30_regulator_prepare_reboot(struct tegra_regulator_coupler *tegra,
+					    bool sys_reboot_mode)
+{
+	int err;
+
+	if (!tegra->core_rdev || !tegra->cpu_rdev)
+		return 0;
+
+	WRITE_ONCE(tegra->sys_reboot_mode_req, true);
+
+	/*
+	 * Some devices use CPU soft-reboot method and in this case we
+	 * should ensure that voltages are sane for the reboot by restoring
+	 * the minimum boot levels.
+	 */
+	err = regulator_sync_voltage_rdev(tegra->cpu_rdev);
+	if (err)
+		return err;
+
+	err = regulator_sync_voltage_rdev(tegra->core_rdev);
+	if (err)
+		return err;
+
+	WRITE_ONCE(tegra->sys_reboot_mode_req, sys_reboot_mode);
+
+	return 0;
+}
+
+static int tegra30_regulator_reboot(struct notifier_block *notifier,
+				    unsigned long event, void *cmd)
+{
+	struct tegra_regulator_coupler *tegra;
+	int ret;
+
+	if (event != SYS_RESTART)
+		return NOTIFY_DONE;
+
+	tegra = container_of(notifier, struct tegra_regulator_coupler,
+			     reboot_notifier);
+
+	ret = tegra30_regulator_prepare_reboot(tegra, true);
+
+	return notifier_from_errno(ret);
+}
+
 static int tegra30_regulator_attach(struct regulator_coupler *coupler,
 				    struct regulator_dev *rdev)
 {
@@ -292,6 +367,14 @@ static int tegra30_regulator_detach(struct regulator_coupler *coupler,
 {
 	struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler);
 
+	/*
+	 * We don't expect regulators to be decoupled during reboot,
+	 * this may race with the reboot handler and shouldn't ever
+	 * happen in practice.
+	 */
+	if (WARN_ON_ONCE(system_state > SYSTEM_RUNNING))
+		return -EPERM;
+
 	if (tegra->core_rdev == rdev) {
 		tegra->core_rdev = NULL;
 		return 0;
@@ -311,13 +394,19 @@ static struct tegra_regulator_coupler tegra30_coupler = {
 		.detach_regulator = tegra30_regulator_detach,
 		.balance_voltage = tegra30_regulator_balance_voltage,
 	},
+	.reboot_notifier.notifier_call = tegra30_regulator_reboot,
 };
 
 static int __init tegra_regulator_coupler_init(void)
 {
+	int err;
+
 	if (!of_machine_is_compatible("nvidia,tegra30"))
 		return 0;
 
+	err = register_reboot_notifier(&tegra30_coupler.reboot_notifier);
+	WARN_ON(err);
+
 	return regulator_coupler_register(&tegra30_coupler.coupler);
 }
 arch_initcall(tegra_regulator_coupler_init);