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