From 783807436f363e5b1ad4d43ba7debbedfcadbb99 Mon Sep 17 00:00:00 2001 From: Dmitry Osipenko Date: Thu, 25 Jul 2019 18:18:32 +0300 Subject: 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: Dmitry Osipenko Acked-By: Peter De Schrijver Signed-off-by: Thierry Reding --- drivers/soc/tegra/regulators-tegra30.c | 317 +++++++++++++++++++++++++++++++++ 1 file changed, 317 insertions(+) create mode 100644 drivers/soc/tegra/regulators-tegra30.c (limited to 'drivers/soc/tegra/regulators-tegra30.c') diff --git a/drivers/soc/tegra/regulators-tegra30.c b/drivers/soc/tegra/regulators-tegra30.c new file mode 100644 index 000000000000..8e623ff18e70 --- /dev/null +++ b/drivers/soc/tegra/regulators-tegra30.c @@ -0,0 +1,317 @@ +// 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 +#include +#include +#include +#include +#include + +#include + +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); -- cgit v1.2.3-59-g8ed1b