Commit 78380743 authored by Dmitry Osipenko's avatar Dmitry Osipenko Committed by Thierry Reding
Browse files

soc/tegra: regulators: Add regulators coupler for Tegra30 



Add regulators coupler for Tegra30 SoCs that performs voltage balancing
of a coupled regulators and thus provides voltage scaling functionality.

There are 2 coupled regulators on all Tegra30 SoCs: CORE and CPU. The
coupled regulator voltages shall be in a range of 300mV from each other
and CORE voltage shall be higher than the CPU by N mV, where N depends
on the CPU voltage.

Signed-off-by: default avatarDmitry Osipenko <digetx@gmail.com>
Acked-By: default avatarPeter De Schrijver <pdeschrijver@nvidia.com>
Signed-off-by: default avatarThierry Reding <treding@nvidia.com>
parent 496747e7

drivers/soc/tegra/Kconfig

+5 −0
Original line number Original line Diff line number Diff line
@@ -29,6 +29,7 @@ config ARCH_TEGRA_3x_SOC 
	select PL310_ERRATA_769419 if CACHE_L2X0

	select PL310_ERRATA_769419 if CACHE_L2X0

	select SOC_TEGRA_FLOWCTRL

	select SOC_TEGRA_FLOWCTRL

	select SOC_TEGRA_PMC

	select SOC_TEGRA_PMC

	select SOC_TEGRA30_VOLTAGE_COUPLER

	select TEGRA_TIMER

	select TEGRA_TIMER

	help

	help

	  Support for NVIDIA Tegra T30 processor family, based on the

	  Support for NVIDIA Tegra T30 processor family, based on the
@@ -140,3 +141,7 @@ config SOC_TEGRA_POWERGATE_BPMP 
config SOC_TEGRA20_VOLTAGE_COUPLER

config SOC_TEGRA20_VOLTAGE_COUPLER

	bool "Voltage scaling support for Tegra20 SoCs"

	bool "Voltage scaling support for Tegra20 SoCs"

	depends on ARCH_TEGRA_2x_SOC || COMPILE_TEST

	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

+1 −0
Original line number Original line Diff line number Diff line
@@ -6,3 +6,4 @@ obj-$(CONFIG_SOC_TEGRA_FLOWCTRL) += flowctrl.o 
obj-$(CONFIG_SOC_TEGRA_PMC) += pmc.o

obj-$(CONFIG_SOC_TEGRA_PMC) += pmc.o

obj-$(CONFIG_SOC_TEGRA_POWERGATE_BPMP) += powergate-bpmp.o

obj-$(CONFIG_SOC_TEGRA_POWERGATE_BPMP) += powergate-bpmp.o

obj-$(CONFIG_SOC_TEGRA20_VOLTAGE_COUPLER) += regulators-tegra20.o

obj-$(CONFIG_SOC_TEGRA20_VOLTAGE_COUPLER) += regulators-tegra20.o

obj-$(CONFIG_SOC_TEGRA30_VOLTAGE_COUPLER) += regulators-tegra30.o

drivers/soc/tegra/regulators-tegra30.c

0 → 100644
+317 −0
Original line number Original line Diff line number Diff line 
// 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);

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