diff options
Diffstat (limited to 'drivers/soc/tegra/regulators-tegra20.c')
| -rw-r--r-- | drivers/soc/tegra/regulators-tegra20.c | 371 |
1 files changed, 371 insertions, 0 deletions
diff --git a/drivers/soc/tegra/regulators-tegra20.c b/drivers/soc/tegra/regulators-tegra20.c new file mode 100644 index 000000000..367a71a3c --- /dev/null +++ b/drivers/soc/tegra/regulators-tegra20.c @@ -0,0 +1,371 @@ +// 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); + } + + if (core_uV == core_target_uV) + goto update_rtc; + + 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; +update_rtc: + 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); + } + + if (rtc_uV == rtc_target_uV) + continue; + + 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); |