// 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 #include #include #include #include #include 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);