Merge tag 'tegra-for-5.5-soc' of...

Merge tag 'tegra-for-5.5-soc' of git://git.kernel.org/pub/scm/linux/kernel/git/tegra/linux into arm/drivers

soc/tegra: Changes for v5.5-rc1

Adds wake event support on Tegra210, implements the NVMEM API for the
Tegra FUSE block and adds coupled regulators support for Tegra20 and
Tegra30.

* tag 'tegra-for-5.5-soc' of git://git.kernel.org/pub/scm/linux/kernel/git/tegra/linux:
  soc/tegra: pmc: Remove unnecessary memory barrier
  soc/tegra: pmc: Query PCLK clock rate at probe time
  soc/tegra: regulators: Add regulators coupler for Tegra30
  soc/tegra: regulators: Add regulators coupler for Tegra20
  soc/tegra: pmc: Configure deep sleep control settings
  soc/tegra: pmc: Configure core power request polarity
  soc/tegra: pmc: Add wake event support on Tegra210
  soc/tegra: pmc: Support wake events on more Tegra SoCs
  soc/tegra: fuse: Register cell lookups for compatibility
  soc/tegra: fuse: Add cell information
  soc/tegra: fuse: Implement nvmem device
  soc/tegra: fuse: Restore base on sysfs failure
  soc/tegra: pmc: Fix crashes for hierarchical interrupts
  soc/tegra: fuse: Add FUSE clock check in tegra_fuse_readl()

Link: https://lore.kernel.org/r/20191102144521.3863321-4-thierry.reding@gmail.comSigned-off-by: Olof Johansson <olof@lixom.net>

drivers/soc/tegra/Kconfig

@@ -15,6 +15,7 @@ config ARCH_TEGRA_2x_SOC
 	select PL310_ERRATA_769419 if CACHE_L2X0
 	select SOC_TEGRA_FLOWCTRL
 	select SOC_TEGRA_PMC
+	select SOC_TEGRA20_VOLTAGE_COUPLER
 	select TEGRA_TIMER
 	help
 	  Support for NVIDIA Tegra AP20 and T20 processors, based on the
@@ -28,6 +29,7 @@ config ARCH_TEGRA_3x_SOC
 	select PL310_ERRATA_769419 if CACHE_L2X0
 	select SOC_TEGRA_FLOWCTRL
 	select SOC_TEGRA_PMC
+	select SOC_TEGRA30_VOLTAGE_COUPLER
 	select TEGRA_TIMER
 	help
 	  Support for NVIDIA Tegra T30 processor family, based on the
@@ -135,3 +137,11 @@ config SOC_TEGRA_POWERGATE_BPMP
 	def_bool y
 	depends on PM_GENERIC_DOMAINS
 	depends on TEGRA_BPMP
+
+config SOC_TEGRA20_VOLTAGE_COUPLER
+	bool "Voltage scaling support for Tegra20 SoCs"
+	depends on ARCH_TEGRA_2x_SOC || COMPILE_TEST
+
+config SOC_TEGRA30_VOLTAGE_COUPLER
+	bool "Voltage scaling support for Tegra30 SoCs"
+	depends on ARCH_TEGRA_3x_SOC || COMPILE_TEST

drivers/soc/tegra/Makefile

@@ -5,3 +5,5 @@ obj-y += common.o
 obj-$(CONFIG_SOC_TEGRA_FLOWCTRL) += flowctrl.o
 obj-$(CONFIG_SOC_TEGRA_PMC) += pmc.o
 obj-$(CONFIG_SOC_TEGRA_POWERGATE_BPMP) += powergate-bpmp.o
+obj-$(CONFIG_SOC_TEGRA20_VOLTAGE_COUPLER) += regulators-tegra20.o
+obj-$(CONFIG_SOC_TEGRA30_VOLTAGE_COUPLER) += regulators-tegra30.o

drivers/soc/tegra/fuse/fuse-tegra.c

@@ -8,6 +8,8 @@
 #include <linux/kobject.h>
 #include <linux/init.h>
 #include <linux/io.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/nvmem-provider.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/platform_device.h>
@@ -31,50 +33,6 @@ static const char *tegra_revision_name[TEGRA_REVISION_MAX] = {
 	[TEGRA_REVISION_A04]     = "A04",
 };
 
-static u8 fuse_readb(struct tegra_fuse *fuse, unsigned int offset)
-{
-	u32 val;
-
-	val = fuse->read(fuse, round_down(offset, 4));
-	val >>= (offset % 4) * 8;
-	val &= 0xff;
-
-	return val;
-}
-
-static ssize_t fuse_read(struct file *fd, struct kobject *kobj,
-			 struct bin_attribute *attr, char *buf,
-			 loff_t pos, size_t size)
-{
-	struct device *dev = kobj_to_dev(kobj);
-	struct tegra_fuse *fuse = dev_get_drvdata(dev);
-	int i;
-
-	if (pos < 0 || pos >= attr->size)
-		return 0;
-
-	if (size > attr->size - pos)
-		size = attr->size - pos;
-
-	for (i = 0; i < size; i++)
-		buf[i] = fuse_readb(fuse, pos + i);
-
-	return i;
-}
-
-static struct bin_attribute fuse_bin_attr = {
-	.attr = { .name = "fuse", .mode = S_IRUGO, },
-	.read = fuse_read,
-};
-
-static int tegra_fuse_create_sysfs(struct device *dev, unsigned int size,
-				   const struct tegra_fuse_info *info)
-{
-	fuse_bin_attr.size = size;
-
-	return device_create_bin_file(dev, &fuse_bin_attr);
-}
-
 static const struct of_device_id car_match[] __initconst = {
 	{ .compatible = "nvidia,tegra20-car", },
 	{ .compatible = "nvidia,tegra30-car", },
@@ -115,9 +73,111 @@ static const struct of_device_id tegra_fuse_match[] = {
 	{ /* sentinel */ }
 };
 
+static int tegra_fuse_read(void *priv, unsigned int offset, void *value,
+			   size_t bytes)
+{
+	unsigned int count = bytes / 4, i;
+	struct tegra_fuse *fuse = priv;
+	u32 *buffer = value;
+
+	for (i = 0; i < count; i++)
+		buffer[i] = fuse->read(fuse, offset + i * 4);
+
+	return 0;
+}
+
+static const struct nvmem_cell_info tegra_fuse_cells[] = {
+	{
+		.name = "tsensor-cpu1",
+		.offset = 0x084,
+		.bytes = 4,
+		.bit_offset = 0,
+		.nbits = 32,
+	}, {
+		.name = "tsensor-cpu2",
+		.offset = 0x088,
+		.bytes = 4,
+		.bit_offset = 0,
+		.nbits = 32,
+	}, {
+		.name = "tsensor-cpu0",
+		.offset = 0x098,
+		.bytes = 4,
+		.bit_offset = 0,
+		.nbits = 32,
+	}, {
+		.name = "xusb-pad-calibration",
+		.offset = 0x0f0,
+		.bytes = 4,
+		.bit_offset = 0,
+		.nbits = 32,
+	}, {
+		.name = "tsensor-cpu3",
+		.offset = 0x12c,
+		.bytes = 4,
+		.bit_offset = 0,
+		.nbits = 32,
+	}, {
+		.name = "sata-calibration",
+		.offset = 0x124,
+		.bytes = 1,
+		.bit_offset = 0,
+		.nbits = 2,
+	}, {
+		.name = "tsensor-gpu",
+		.offset = 0x154,
+		.bytes = 4,
+		.bit_offset = 0,
+		.nbits = 32,
+	}, {
+		.name = "tsensor-mem0",
+		.offset = 0x158,
+		.bytes = 4,
+		.bit_offset = 0,
+		.nbits = 32,
+	}, {
+		.name = "tsensor-mem1",
+		.offset = 0x15c,
+		.bytes = 4,
+		.bit_offset = 0,
+		.nbits = 32,
+	}, {
+		.name = "tsensor-pllx",
+		.offset = 0x160,
+		.bytes = 4,
+		.bit_offset = 0,
+		.nbits = 32,
+	}, {
+		.name = "tsensor-common",
+		.offset = 0x180,
+		.bytes = 4,
+		.bit_offset = 0,
+		.nbits = 32,
+	}, {
+		.name = "tsensor-realignment",
+		.offset = 0x1fc,
+		.bytes = 4,
+		.bit_offset = 0,
+		.nbits = 32,
+	}, {
+		.name = "gpu-calibration",
+		.offset = 0x204,
+		.bytes = 4,
+		.bit_offset = 0,
+		.nbits = 32,
+	}, {
+		.name = "xusb-pad-calibration-ext",
+		.offset = 0x250,
+		.bytes = 4,
+		.bit_offset = 0,
+		.nbits = 32,
+	},
+};
+
 static int tegra_fuse_probe(struct platform_device *pdev)
 {
 	void __iomem *base = fuse->base;
+	struct nvmem_config nvmem;
 	struct resource *res;
 	int err;
 
@@ -146,20 +206,42 @@ static int tegra_fuse_probe(struct platform_device *pdev)
 
 	if (fuse->soc->probe) {
 		err = fuse->soc->probe(fuse);
-		if (err < 0) {
-			fuse->base = base;
-			return err;
-		}
+		if (err < 0)
+			goto restore;
 	}
 
-	if (tegra_fuse_create_sysfs(&pdev->dev, fuse->soc->info->size,
-				    fuse->soc->info))
-		return -ENODEV;
+	memset(&nvmem, 0, sizeof(nvmem));
+	nvmem.dev = &pdev->dev;
+	nvmem.name = "fuse";
+	nvmem.id = -1;
+	nvmem.owner = THIS_MODULE;
+	nvmem.cells = tegra_fuse_cells;
+	nvmem.ncells = ARRAY_SIZE(tegra_fuse_cells);
+	nvmem.type = NVMEM_TYPE_OTP;
+	nvmem.read_only = true;
+	nvmem.root_only = true;
+	nvmem.reg_read = tegra_fuse_read;
+	nvmem.size = fuse->soc->info->size;
+	nvmem.word_size = 4;
+	nvmem.stride = 4;
+	nvmem.priv = fuse;
+
+	fuse->nvmem = devm_nvmem_register(&pdev->dev, &nvmem);
+	if (IS_ERR(fuse->nvmem)) {
+		err = PTR_ERR(fuse->nvmem);
+		dev_err(&pdev->dev, "failed to register NVMEM device: %d\n",
+			err);
+		goto restore;
+	}
 
 	/* release the early I/O memory mapping */
 	iounmap(base);
 
 	return 0;
+
+restore:
+	fuse->base = base;
+	return err;
 }
 
 static struct platform_driver tegra_fuse_driver = {
@@ -186,9 +268,12 @@ u32 __init tegra_fuse_read_early(unsigned int offset)
 
 int tegra_fuse_readl(unsigned long offset, u32 *value)
 {
-	if (!fuse->read)
+	if (!fuse->read || !fuse->clk)
 		return -EPROBE_DEFER;
 
+	if (IS_ERR(fuse->clk))
+		return PTR_ERR(fuse->clk);
+
 	*value = fuse->read(fuse, offset);
 
 	return 0;
@@ -338,6 +423,15 @@ static int __init tegra_init_fuse(void)
 	pr_debug("Tegra CPU Speedo ID %d, SoC Speedo ID %d\n",
 		 tegra_sku_info.cpu_speedo_id, tegra_sku_info.soc_speedo_id);
 
+	if (fuse->soc->lookups) {
+		size_t size = sizeof(*fuse->lookups) * fuse->soc->num_lookups;
+
+		fuse->lookups = kmemdup(fuse->soc->lookups, size, GFP_KERNEL);
+		if (!fuse->lookups)
+			return -ENOMEM;
+
+		nvmem_add_cell_lookups(fuse->lookups, fuse->soc->num_lookups);
+	}
 
 	return 0;
 }

drivers/soc/tegra/fuse/fuse-tegra30.c

@@ -8,6 +8,7 @@
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
+#include <linux/nvmem-consumer.h>
 #include <linux/of_device.h>
 #include <linux/of_address.h>
 #include <linux/platform_device.h>
@@ -127,6 +128,70 @@ const struct tegra_fuse_soc tegra114_fuse_soc = {
 #endif
 
 #if defined(CONFIG_ARCH_TEGRA_124_SOC) || defined(CONFIG_ARCH_TEGRA_132_SOC)
+static const struct nvmem_cell_lookup tegra124_fuse_lookups[] = {
+	{
+		.nvmem_name = "fuse",
+		.cell_name = "xusb-pad-calibration",
+		.dev_id = "7009f000.padctl",
+		.con_id = "calibration",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "sata-calibration",
+		.dev_id = "70020000.sata",
+		.con_id = "calibration",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "tsensor-common",
+		.dev_id = "700e2000.thermal-sensor",
+		.con_id = "common",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "tsensor-realignment",
+		.dev_id = "700e2000.thermal-sensor",
+		.con_id = "realignment",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "tsensor-cpu0",
+		.dev_id = "700e2000.thermal-sensor",
+		.con_id = "cpu0",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "tsensor-cpu1",
+		.dev_id = "700e2000.thermal-sensor",
+		.con_id = "cpu1",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "tsensor-cpu2",
+		.dev_id = "700e2000.thermal-sensor",
+		.con_id = "cpu2",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "tsensor-cpu3",
+		.dev_id = "700e2000.thermal-sensor",
+		.con_id = "cpu3",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "tsensor-mem0",
+		.dev_id = "700e2000.thermal-sensor",
+		.con_id = "mem0",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "tsensor-mem1",
+		.dev_id = "700e2000.thermal-sensor",
+		.con_id = "mem1",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "tsensor-gpu",
+		.dev_id = "700e2000.thermal-sensor",
+		.con_id = "gpu",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "tsensor-pllx",
+		.dev_id = "700e2000.thermal-sensor",
+		.con_id = "pllx",
+	},
+};
+
 static const struct tegra_fuse_info tegra124_fuse_info = {
 	.read = tegra30_fuse_read,
 	.size = 0x300,
@@ -137,10 +202,81 @@ const struct tegra_fuse_soc tegra124_fuse_soc = {
 	.init = tegra30_fuse_init,
 	.speedo_init = tegra124_init_speedo_data,
 	.info = &tegra124_fuse_info,
+	.lookups = tegra124_fuse_lookups,
+	.num_lookups = ARRAY_SIZE(tegra124_fuse_lookups),
 };
 #endif
 
 #if defined(CONFIG_ARCH_TEGRA_210_SOC)
+static const struct nvmem_cell_lookup tegra210_fuse_lookups[] = {
+	{
+		.nvmem_name = "fuse",
+		.cell_name = "tsensor-cpu1",
+		.dev_id = "700e2000.thermal-sensor",
+		.con_id = "cpu1",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "tsensor-cpu2",
+		.dev_id = "700e2000.thermal-sensor",
+		.con_id = "cpu2",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "tsensor-cpu0",
+		.dev_id = "700e2000.thermal-sensor",
+		.con_id = "cpu0",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "xusb-pad-calibration",
+		.dev_id = "7009f000.padctl",
+		.con_id = "calibration",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "tsensor-cpu3",
+		.dev_id = "700e2000.thermal-sensor",
+		.con_id = "cpu3",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "sata-calibration",
+		.dev_id = "70020000.sata",
+		.con_id = "calibration",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "tsensor-gpu",
+		.dev_id = "700e2000.thermal-sensor",
+		.con_id = "gpu",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "tsensor-mem0",
+		.dev_id = "700e2000.thermal-sensor",
+		.con_id = "mem0",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "tsensor-mem1",
+		.dev_id = "700e2000.thermal-sensor",
+		.con_id = "mem1",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "tsensor-pllx",
+		.dev_id = "700e2000.thermal-sensor",
+		.con_id = "pllx",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "tsensor-common",
+		.dev_id = "700e2000.thermal-sensor",
+		.con_id = "common",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "gpu-calibration",
+		.dev_id = "57000000.gpu",
+		.con_id = "calibration",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "xusb-pad-calibration-ext",
+		.dev_id = "7009f000.padctl",
+		.con_id = "calibration-ext",
+	},
+};
+
 static const struct tegra_fuse_info tegra210_fuse_info = {
 	.read = tegra30_fuse_read,
 	.size = 0x300,
@@ -151,10 +287,26 @@ const struct tegra_fuse_soc tegra210_fuse_soc = {
 	.init = tegra30_fuse_init,
 	.speedo_init = tegra210_init_speedo_data,
 	.info = &tegra210_fuse_info,
+	.lookups = tegra210_fuse_lookups,
+	.num_lookups = ARRAY_SIZE(tegra210_fuse_lookups),
 };
 #endif
 
 #if defined(CONFIG_ARCH_TEGRA_186_SOC)
+static const struct nvmem_cell_lookup tegra186_fuse_lookups[] = {
+	{
+		.nvmem_name = "fuse",
+		.cell_name = "xusb-pad-calibration",
+		.dev_id = "3520000.padctl",
+		.con_id = "calibration",
+	}, {
+		.nvmem_name = "fuse",
+		.cell_name = "xusb-pad-calibration-ext",
+		.dev_id = "3520000.padctl",
+		.con_id = "calibration-ext",
+	},
+};
+
 static const struct tegra_fuse_info tegra186_fuse_info = {
 	.read = tegra30_fuse_read,
 	.size = 0x300,
@@ -164,5 +316,7 @@ static const struct tegra_fuse_info tegra186_fuse_info = {
 const struct tegra_fuse_soc tegra186_fuse_soc = {
 	.init = tegra30_fuse_init,
 	.info = &tegra186_fuse_info,
+	.lookups = tegra186_fuse_lookups,
+	.num_lookups = ARRAY_SIZE(tegra186_fuse_lookups),
 };
 #endif

drivers/soc/tegra/fuse/fuse.h

@@ -13,6 +13,8 @@
 #include <linux/dmaengine.h>
 #include <linux/types.h>
 
+struct nvmem_cell_lookup;
+struct nvmem_device;
 struct tegra_fuse;
 
 struct tegra_fuse_info {
@@ -27,6 +29,9 @@ struct tegra_fuse_soc {
 	int (*probe)(struct tegra_fuse *fuse);
 
 	const struct tegra_fuse_info *info;
+
+	const struct nvmem_cell_lookup *lookups;
+	unsigned int num_lookups;
 };
 
 struct tegra_fuse {
@@ -48,6 +53,9 @@ struct tegra_fuse {
 		dma_addr_t phys;
 		u32 *virt;
 	} apbdma;
+
+	struct nvmem_device *nvmem;
+	struct nvmem_cell_lookup *lookups;
 };
 
 void tegra_init_revision(void);

drivers/soc/tegra/regulators-tegra20.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Voltage regulators coupler for NVIDIA Tegra20
+ * Copyright (C) 2019 GRATE-DRIVER project
+ *
+ * Voltage constraints borrowed from downstream kernel sources
+ * Copyright (C) 2010-2011 NVIDIA Corporation
+ */
+
+#define pr_fmt(fmt)	"tegra voltage-coupler: " fmt
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/regulator/coupler.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+
+struct tegra_regulator_coupler {
+	struct regulator_coupler coupler;
+	struct regulator_dev *core_rdev;
+	struct regulator_dev *cpu_rdev;
+	struct regulator_dev *rtc_rdev;
+	int core_min_uV;
+};
+
+static inline struct tegra_regulator_coupler *
+to_tegra_coupler(struct regulator_coupler *coupler)
+{
+	return container_of(coupler, struct tegra_regulator_coupler, coupler);
+}
+
+static int tegra20_core_limit(struct tegra_regulator_coupler *tegra,
+			      struct regulator_dev *core_rdev)
+{
+	int core_min_uV = 0;
+	int core_max_uV;
+	int core_cur_uV;
+	int err;
+
+	if (tegra->core_min_uV > 0)
+		return tegra->core_min_uV;
+
+	core_cur_uV = regulator_get_voltage_rdev(core_rdev);
+	if (core_cur_uV < 0)
+		return core_cur_uV;
+
+	core_max_uV = max(core_cur_uV, 1200000);
+
+	err = regulator_check_voltage(core_rdev, &core_min_uV, &core_max_uV);
+	if (err)
+		return err;
+
+	/*
+	 * Limit minimum CORE voltage to a value left from bootloader or,
+	 * if it's unreasonably low value, to the most common 1.2v or to
+	 * whatever maximum value defined via board's device-tree.
+	 */
+	tegra->core_min_uV = core_max_uV;
+
+	pr_info("core minimum voltage limited to %duV\n", tegra->core_min_uV);
+
+	return tegra->core_min_uV;
+}
+
+static int tegra20_core_rtc_max_spread(struct regulator_dev *core_rdev,
+				       struct regulator_dev *rtc_rdev)
+{
+	struct coupling_desc *c_desc = &core_rdev->coupling_desc;
+	struct regulator_dev *rdev;
+	int max_spread;
+	unsigned int i;
+
+	for (i = 1; i < c_desc->n_coupled; i++) {
+		max_spread = core_rdev->constraints->max_spread[i - 1];
+		rdev = c_desc->coupled_rdevs[i];
+
+		if (rdev == rtc_rdev && max_spread)
+			return max_spread;
+	}
+
+	pr_err_once("rtc-core max-spread is undefined in device-tree\n");
+
+	return 150000;
+}
+
+static int tegra20_core_rtc_update(struct tegra_regulator_coupler *tegra,
+				   struct regulator_dev *core_rdev,
+				   struct regulator_dev *rtc_rdev,
+				   int cpu_uV, int cpu_min_uV)
+{
+	int core_min_uV, core_max_uV = INT_MAX;
+	int rtc_min_uV, rtc_max_uV = INT_MAX;
+	int core_target_uV;
+	int rtc_target_uV;
+	int max_spread;
+	int core_uV;
+	int rtc_uV;
+	int err;
+
+	/*
+	 * RTC and CORE voltages should be no more than 170mV from each other,
+	 * CPU should be below RTC and CORE by at least 120mV. This applies
+	 * to all Tegra20 SoC's.
+	 */
+	max_spread = tegra20_core_rtc_max_spread(core_rdev, rtc_rdev);
+
+	/*
+	 * The core voltage scaling is currently not hooked up in drivers,
+	 * hence we will limit the minimum core voltage to a reasonable value.
+	 * This should be good enough for the time being.
+	 */
+	core_min_uV = tegra20_core_limit(tegra, core_rdev);
+	if (core_min_uV < 0)
+		return core_min_uV;
+
+	err = regulator_check_voltage(core_rdev, &core_min_uV, &core_max_uV);
+	if (err)
+		return err;
+
+	err = regulator_check_consumers(core_rdev, &core_min_uV, &core_max_uV,
+					PM_SUSPEND_ON);
+	if (err)
+		return err;
+
+	core_uV = regulator_get_voltage_rdev(core_rdev);
+	if (core_uV < 0)
+		return core_uV;
+
+	core_min_uV = max(cpu_min_uV + 125000, core_min_uV);
+	if (core_min_uV > core_max_uV)
+		return -EINVAL;
+
+	if (cpu_uV + 120000 > core_uV)
+		pr_err("core-cpu voltage constraint violated: %d %d\n",
+		       core_uV, cpu_uV + 120000);
+
+	rtc_uV = regulator_get_voltage_rdev(rtc_rdev);
+	if (rtc_uV < 0)
+		return rtc_uV;
+
+	if (cpu_uV + 120000 > rtc_uV)
+		pr_err("rtc-cpu voltage constraint violated: %d %d\n",
+		       rtc_uV, cpu_uV + 120000);
+
+	if (abs(core_uV - rtc_uV) > 170000)
+		pr_err("core-rtc voltage constraint violated: %d %d\n",
+		       core_uV, rtc_uV);
+
+	rtc_min_uV = max(cpu_min_uV + 125000, core_min_uV - max_spread);
+
+	err = regulator_check_voltage(rtc_rdev, &rtc_min_uV, &rtc_max_uV);
+	if (err)
+		return err;
+
+	while (core_uV != core_min_uV || rtc_uV != rtc_min_uV) {
+		if (core_uV < core_min_uV) {
+			core_target_uV = min(core_uV + max_spread, core_min_uV);
+			core_target_uV = min(rtc_uV + max_spread, core_target_uV);
+		} else {
+			core_target_uV = max(core_uV - max_spread, core_min_uV);
+			core_target_uV = max(rtc_uV - max_spread, core_target_uV);
+		}
+
+		err = regulator_set_voltage_rdev(core_rdev,
+						 core_target_uV,
+						 core_max_uV,
+						 PM_SUSPEND_ON);
+		if (err)
+			return err;
+
+		core_uV = core_target_uV;
+
+		if (rtc_uV < rtc_min_uV) {
+			rtc_target_uV = min(rtc_uV + max_spread, rtc_min_uV);
+			rtc_target_uV = min(core_uV + max_spread, rtc_target_uV);
+		} else {
+			rtc_target_uV = max(rtc_uV - max_spread, rtc_min_uV);
+			rtc_target_uV = max(core_uV - max_spread, rtc_target_uV);
+		}
+
+		err = regulator_set_voltage_rdev(rtc_rdev,
+						 rtc_target_uV,
+						 rtc_max_uV,
+						 PM_SUSPEND_ON);
+		if (err)
+			return err;
+
+		rtc_uV = rtc_target_uV;
+	}
+
+	return 0;
+}
+
+static int tegra20_core_voltage_update(struct tegra_regulator_coupler *tegra,
+				       struct regulator_dev *cpu_rdev,
+				       struct regulator_dev *core_rdev,
+				       struct regulator_dev *rtc_rdev)
+{
+	int cpu_uV;
+
+	cpu_uV = regulator_get_voltage_rdev(cpu_rdev);
+	if (cpu_uV < 0)
+		return cpu_uV;
+
+	return tegra20_core_rtc_update(tegra, core_rdev, rtc_rdev,
+				       cpu_uV, cpu_uV);
+}
+
+static int tegra20_cpu_voltage_update(struct tegra_regulator_coupler *tegra,
+				      struct regulator_dev *cpu_rdev,
+				      struct regulator_dev *core_rdev,
+				      struct regulator_dev *rtc_rdev)
+{
+	int cpu_min_uV_consumers = 0;
+	int cpu_max_uV = INT_MAX;
+	int cpu_min_uV = 0;
+	int cpu_uV;
+	int err;
+
+	err = regulator_check_voltage(cpu_rdev, &cpu_min_uV, &cpu_max_uV);
+	if (err)
+		return err;
+
+	err = regulator_check_consumers(cpu_rdev, &cpu_min_uV, &cpu_max_uV,
+					PM_SUSPEND_ON);
+	if (err)
+		return err;
+
+	err = regulator_check_consumers(cpu_rdev, &cpu_min_uV_consumers,
+					&cpu_max_uV, PM_SUSPEND_ON);
+	if (err)
+		return err;
+
+	cpu_uV = regulator_get_voltage_rdev(cpu_rdev);
+	if (cpu_uV < 0)
+		return 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
+	 * survive the voltage drop if it's running on a higher frequency.
+	 */
+	if (!cpu_min_uV_consumers)
+		cpu_min_uV = cpu_uV;
+
+	if (cpu_min_uV > cpu_uV) {
+		err = tegra20_core_rtc_update(tegra, core_rdev, rtc_rdev,
+					      cpu_uV, cpu_min_uV);
+		if (err)
+			return err;
+
+		err = regulator_set_voltage_rdev(cpu_rdev, cpu_min_uV,
+						 cpu_max_uV, PM_SUSPEND_ON);
+		if (err)
+			return err;
+	} else if (cpu_min_uV < cpu_uV)  {
+		err = regulator_set_voltage_rdev(cpu_rdev, cpu_min_uV,
+						 cpu_max_uV, PM_SUSPEND_ON);
+		if (err)
+			return err;
+
+		err = tegra20_core_rtc_update(tegra, core_rdev, rtc_rdev,
+					      cpu_uV, cpu_min_uV);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static int tegra20_regulator_balance_voltage(struct regulator_coupler *coupler,
+					     struct regulator_dev *rdev,
+					     suspend_state_t state)
+{
+	struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler);
+	struct regulator_dev *core_rdev = tegra->core_rdev;
+	struct regulator_dev *cpu_rdev = tegra->cpu_rdev;
+	struct regulator_dev *rtc_rdev = tegra->rtc_rdev;
+
+	if ((core_rdev != rdev && cpu_rdev != rdev && rtc_rdev != rdev) ||
+	    state != PM_SUSPEND_ON) {
+		pr_err("regulators are not coupled properly\n");
+		return -EINVAL;
+	}
+
+	if (rdev == cpu_rdev)
+		return tegra20_cpu_voltage_update(tegra, cpu_rdev,
+						  core_rdev, rtc_rdev);
+
+	if (rdev == core_rdev)
+		return tegra20_core_voltage_update(tegra, cpu_rdev,
+						   core_rdev, rtc_rdev);
+
+	pr_err("changing %s voltage not permitted\n", rdev_get_name(rtc_rdev));
+
+	return -EPERM;
+}
+
+static int tegra20_regulator_attach(struct regulator_coupler *coupler,
+				    struct regulator_dev *rdev)
+{
+	struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler);
+	struct device_node *np = rdev->dev.of_node;
+
+	if (of_property_read_bool(np, "nvidia,tegra-core-regulator") &&
+	    !tegra->core_rdev) {
+		tegra->core_rdev = rdev;
+		return 0;
+	}
+
+	if (of_property_read_bool(np, "nvidia,tegra-rtc-regulator") &&
+	    !tegra->rtc_rdev) {
+		tegra->rtc_rdev = rdev;
+		return 0;
+	}
+
+	if (of_property_read_bool(np, "nvidia,tegra-cpu-regulator") &&
+	    !tegra->cpu_rdev) {
+		tegra->cpu_rdev = rdev;
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+static int tegra20_regulator_detach(struct regulator_coupler *coupler,
+				    struct regulator_dev *rdev)
+{
+	struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler);
+
+	if (tegra->core_rdev == rdev) {
+		tegra->core_rdev = NULL;
+		return 0;
+	}
+
+	if (tegra->rtc_rdev == rdev) {
+		tegra->rtc_rdev = NULL;
+		return 0;
+	}
+
+	if (tegra->cpu_rdev == rdev) {
+		tegra->cpu_rdev = NULL;
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+static struct tegra_regulator_coupler tegra20_coupler = {
+	.coupler = {
+		.attach_regulator = tegra20_regulator_attach,
+		.detach_regulator = tegra20_regulator_detach,
+		.balance_voltage = tegra20_regulator_balance_voltage,
+	},
+};
+
+static int __init tegra_regulator_coupler_init(void)
+{
+	if (!of_machine_is_compatible("nvidia,tegra20"))
+		return 0;
+
+	return regulator_coupler_register(&tegra20_coupler.coupler);
+}
+arch_initcall(tegra_regulator_coupler_init);

drivers/soc/tegra/regulators-tegra30.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Voltage regulators coupler for NVIDIA Tegra30
+ * Copyright (C) 2019 GRATE-DRIVER project
+ *
+ * Voltage constraints borrowed from downstream kernel sources
+ * Copyright (C) 2010-2011 NVIDIA Corporation
+ */
+
+#define pr_fmt(fmt)	"tegra voltage-coupler: " fmt
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/regulator/coupler.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+
+#include <soc/tegra/fuse.h>
+
+struct tegra_regulator_coupler {
+	struct regulator_coupler coupler;
+	struct regulator_dev *core_rdev;
+	struct regulator_dev *cpu_rdev;
+	int core_min_uV;
+};
+
+static inline struct tegra_regulator_coupler *
+to_tegra_coupler(struct regulator_coupler *coupler)
+{
+	return container_of(coupler, struct tegra_regulator_coupler, coupler);
+}
+
+static int tegra30_core_limit(struct tegra_regulator_coupler *tegra,
+			      struct regulator_dev *core_rdev)
+{
+	int core_min_uV = 0;
+	int core_max_uV;
+	int core_cur_uV;
+	int err;
+
+	if (tegra->core_min_uV > 0)
+		return tegra->core_min_uV;
+
+	core_cur_uV = regulator_get_voltage_rdev(core_rdev);
+	if (core_cur_uV < 0)
+		return core_cur_uV;
+
+	core_max_uV = max(core_cur_uV, 1200000);
+
+	err = regulator_check_voltage(core_rdev, &core_min_uV, &core_max_uV);
+	if (err)
+		return err;
+
+	/*
+	 * Limit minimum CORE voltage to a value left from bootloader or,
+	 * if it's unreasonably low value, to the most common 1.2v or to
+	 * whatever maximum value defined via board's device-tree.
+	 */
+	tegra->core_min_uV = core_max_uV;
+
+	pr_info("core minimum voltage limited to %duV\n", tegra->core_min_uV);
+
+	return tegra->core_min_uV;
+}
+
+static int tegra30_core_cpu_limit(int cpu_uV)
+{
+	if (cpu_uV < 800000)
+		return 950000;
+
+	if (cpu_uV < 900000)
+		return 1000000;
+
+	if (cpu_uV < 1000000)
+		return 1100000;
+
+	if (cpu_uV < 1100000)
+		return 1200000;
+
+	if (cpu_uV < 1250000) {
+		switch (tegra_sku_info.cpu_speedo_id) {
+		case 0 ... 1:
+		case 4:
+		case 7 ... 8:
+			return 1200000;
+
+		default:
+			return 1300000;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static int tegra30_voltage_update(struct tegra_regulator_coupler *tegra,
+				  struct regulator_dev *cpu_rdev,
+				  struct regulator_dev *core_rdev)
+{
+	int core_min_uV, core_max_uV = INT_MAX;
+	int cpu_min_uV, cpu_max_uV = INT_MAX;
+	int cpu_min_uV_consumers = 0;
+	int core_min_limited_uV;
+	int core_target_uV;
+	int cpu_target_uV;
+	int core_max_step;
+	int cpu_max_step;
+	int max_spread;
+	int core_uV;
+	int cpu_uV;
+	int err;
+
+	/*
+	 * CPU voltage should not got lower than 300mV from the CORE.
+	 * CPU voltage should stay below the CORE by 100mV+, depending
+	 * by the CORE voltage. This applies to all Tegra30 SoC's.
+	 */
+	max_spread = cpu_rdev->constraints->max_spread[0];
+	cpu_max_step = cpu_rdev->constraints->max_uV_step;
+	core_max_step = core_rdev->constraints->max_uV_step;
+
+	if (!max_spread) {
+		pr_err_once("cpu-core max-spread is undefined in device-tree\n");
+		max_spread = 300000;
+	}
+
+	if (!cpu_max_step) {
+		pr_err_once("cpu max-step is undefined in device-tree\n");
+		cpu_max_step = 150000;
+	}
+
+	if (!core_max_step) {
+		pr_err_once("core max-step is undefined in device-tree\n");
+		core_max_step = 150000;
+	}
+
+	/*
+	 * The CORE voltage scaling is currently not hooked up in drivers,
+	 * hence we will limit the minimum CORE voltage to a reasonable value.
+	 * This should be good enough for the time being.
+	 */
+	core_min_uV = tegra30_core_limit(tegra, core_rdev);
+	if (core_min_uV < 0)
+		return core_min_uV;
+
+	err = regulator_check_consumers(core_rdev, &core_min_uV, &core_max_uV,
+					PM_SUSPEND_ON);
+	if (err)
+		return err;
+
+	core_uV = regulator_get_voltage_rdev(core_rdev);
+	if (core_uV < 0)
+		return core_uV;
+
+	cpu_min_uV = core_min_uV - max_spread;
+
+	err = regulator_check_consumers(cpu_rdev, &cpu_min_uV, &cpu_max_uV,
+					PM_SUSPEND_ON);
+	if (err)
+		return err;
+
+	err = regulator_check_consumers(cpu_rdev, &cpu_min_uV_consumers,
+					&cpu_max_uV, PM_SUSPEND_ON);
+	if (err)
+		return err;
+
+	err = regulator_check_voltage(cpu_rdev, &cpu_min_uV, &cpu_max_uV);
+	if (err)
+		return err;
+
+	cpu_uV = regulator_get_voltage_rdev(cpu_rdev);
+	if (cpu_uV < 0)
+		return 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
+	 * survive the voltage drop if it's running on a higher frequency.
+	 */
+	if (!cpu_min_uV_consumers)
+		cpu_min_uV = cpu_uV;
+
+	/*
+	 * Bootloader shall set up voltages correctly, but if it
+	 * happens that there is a violation, then try to fix it
+	 * at first.
+	 */
+	core_min_limited_uV = tegra30_core_cpu_limit(cpu_uV);
+	if (core_min_limited_uV < 0)
+		return core_min_limited_uV;
+
+	core_min_uV = max(core_min_uV, tegra30_core_cpu_limit(cpu_min_uV));
+
+	err = regulator_check_voltage(core_rdev, &core_min_uV, &core_max_uV);
+	if (err)
+		return err;
+
+	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);
+		goto update_core;
+	}
+
+	while (cpu_uV != cpu_min_uV || core_uV != core_min_uV) {
+		if (cpu_uV < cpu_min_uV) {
+			cpu_target_uV = min(cpu_uV + cpu_max_step, cpu_min_uV);
+		} else {
+			cpu_target_uV = max(cpu_uV - cpu_max_step, cpu_min_uV);
+			cpu_target_uV = max(core_uV - max_spread, cpu_target_uV);
+		}
+
+		err = regulator_set_voltage_rdev(cpu_rdev,
+						 cpu_target_uV,
+						 cpu_max_uV,
+						 PM_SUSPEND_ON);
+		if (err)
+			return err;
+
+		cpu_uV = cpu_target_uV;
+update_core:
+		core_min_limited_uV = tegra30_core_cpu_limit(cpu_uV);
+		if (core_min_limited_uV < 0)
+			return core_min_limited_uV;
+
+		core_target_uV = max(core_min_limited_uV, core_min_uV);
+
+		if (core_uV < core_target_uV) {
+			core_target_uV = min(core_target_uV, core_uV + core_max_step);
+			core_target_uV = min(core_target_uV, cpu_uV + max_spread);
+		} else {
+			core_target_uV = max(core_target_uV, core_uV - core_max_step);
+		}
+
+		err = regulator_set_voltage_rdev(core_rdev,
+						 core_target_uV,
+						 core_max_uV,
+						 PM_SUSPEND_ON);
+		if (err)
+			return err;
+
+		core_uV = core_target_uV;
+	}
+
+	return 0;
+}
+
+static int tegra30_regulator_balance_voltage(struct regulator_coupler *coupler,
+					     struct regulator_dev *rdev,
+					     suspend_state_t state)
+{
+	struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler);
+	struct regulator_dev *core_rdev = tegra->core_rdev;
+	struct regulator_dev *cpu_rdev = tegra->cpu_rdev;
+
+	if ((core_rdev != rdev && cpu_rdev != rdev) || state != PM_SUSPEND_ON) {
+		pr_err("regulators are not coupled properly\n");
+		return -EINVAL;
+	}
+
+	return tegra30_voltage_update(tegra, cpu_rdev, core_rdev);
+}
+
+static int tegra30_regulator_attach(struct regulator_coupler *coupler,
+				    struct regulator_dev *rdev)
+{
+	struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler);
+	struct device_node *np = rdev->dev.of_node;
+
+	if (of_property_read_bool(np, "nvidia,tegra-core-regulator") &&
+	    !tegra->core_rdev) {
+		tegra->core_rdev = rdev;
+		return 0;
+	}
+
+	if (of_property_read_bool(np, "nvidia,tegra-cpu-regulator") &&
+	    !tegra->cpu_rdev) {
+		tegra->cpu_rdev = rdev;
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+static int tegra30_regulator_detach(struct regulator_coupler *coupler,
+				    struct regulator_dev *rdev)
+{
+	struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler);
+
+	if (tegra->core_rdev == rdev) {
+		tegra->core_rdev = NULL;
+		return 0;
+	}
+
+	if (tegra->cpu_rdev == rdev) {
+		tegra->cpu_rdev = NULL;
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+static struct tegra_regulator_coupler tegra30_coupler = {
+	.coupler = {
+		.attach_regulator = tegra30_regulator_attach,
+		.detach_regulator = tegra30_regulator_detach,
+		.balance_voltage = tegra30_regulator_balance_voltage,
+	},
+};
+
+static int __init tegra_regulator_coupler_init(void)
+{
+	if (!of_machine_is_compatible("nvidia,tegra30"))
+		return 0;
+
+	return regulator_coupler_register(&tegra30_coupler.coupler);
+}
+arch_initcall(tegra_regulator_coupler_init);