in tegra/regulators-tegra30.c [166:339]
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;
/* prepare voltage level for suspend */
if (tegra->sys_suspend_mode)
core_min_uV = clamp(tegra30_core_nominal_uV(),
core_min_uV, core_max_uV);
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;
/* store boot voltage level */
if (!tegra->cpu_min_uV)
tegra->cpu_min_uV = 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 = max(cpu_uV, cpu_min_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;
/* restore boot voltage level */
if (tegra->sys_reboot_mode)
cpu_min_uV = max(cpu_min_uV, tegra->cpu_min_uV);
/* prepare voltage level for suspend */
if (tegra->sys_suspend_mode)
cpu_min_uV = clamp(tegra30_cpu_nominal_uV(),
cpu_min_uV, cpu_max_uV);
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);
}
if (cpu_uV == cpu_target_uV)
goto update_core;
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);
}
if (core_uV == core_target_uV)
continue;
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;
}