// 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/reboot.h>
#include <linux/regulator/coupler.h>
#include <linux/regulator/driver.h>
#include <linux/regulator/machine.h>
#include <linux/suspend.h>
#include <soc/tegra/fuse.h>
#include <soc/tegra/pmc.h>
struct tegra_regulator_coupler {
struct regulator_coupler coupler;
struct regulator_dev *core_rdev;
struct regulator_dev *cpu_rdev;
struct regulator_dev *rtc_rdev;
struct notifier_block reboot_notifier;
struct notifier_block suspend_notifier;
int core_min_uV, cpu_min_uV;
bool sys_reboot_mode_req;
bool sys_reboot_mode;
bool sys_suspend_mode_req;
bool sys_suspend_mode;
};
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;
/*
* Tegra20 SoC has critical DVFS-capable devices that are
* permanently-active or active at a boot time, like EMC
* (DRAM controller) or Display controller for example.
*
* The voltage of a CORE SoC power domain shall not be dropped below
* a minimum level, which is determined by device's clock rate.
* This means that we can't fully allow CORE voltage scaling until
* the state of all DVFS-critical CORE devices is synced.
*/
if (tegra_pmc_core_domain_state_synced() && !tegra->sys_reboot_mode) {
pr_info_once("voltage state synced\n");
return 0;
}
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 voltage initialized 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_cpu_nominal_uV(void)
{
switch (tegra_sku_info.soc_speedo_id) {
case 0:
return 1100000;
case 1:
return 1025000;
default:
return 1125000;
}
}
static int tegra20_core_nominal_uV(void)
{
switch (tegra_sku_info.soc_speedo_id) {
default:
return 1225000;
case 2:
return 1300000;
}
}
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;
/* prepare voltage level for suspend */
if (tegra->sys_suspend_mode)
core_min_uV = clamp(tegra20_core_nominal_uV(),
core_min_uV, core_max_uV);
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;
/* 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 = cpu_uV;
/* 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(tegra20_cpu_nominal_uV(),
cpu_min_uV, cpu_max_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;
}
tegra->sys_reboot_mode = READ_ONCE(tegra->sys_reboot_mode_req);
tegra->sys_suspend_mode = READ_ONCE(tegra->sys_suspend_mode_req);
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_prepare_suspend(struct tegra_regulator_coupler *tegra,
bool sys_suspend_mode)
{
int err;
if (!tegra->core_rdev || !tegra->rtc_rdev || !tegra->cpu_rdev)
return 0;
/*
* All power domains are enabled early during resume from suspend
* by GENPD core. Domains like VENC may require a higher voltage
* when enabled during resume from suspend. This also prepares
* hardware for resuming from LP0.
*/
WRITE_ONCE(tegra->sys_suspend_mode_req, sys_suspend_mode);
err = regulator_sync_voltage_rdev(tegra->cpu_rdev);
if (err)
return err;
err = regulator_sync_voltage_rdev(tegra->core_rdev);
if (err)
return err;
return 0;
}
static int tegra20_regulator_suspend(struct notifier_block *notifier,
unsigned long mode, void *arg)
{
struct tegra_regulator_coupler *tegra;
int ret = 0;
tegra = container_of(notifier, struct tegra_regulator_coupler,
suspend_notifier);
switch (mode) {
case PM_HIBERNATION_PREPARE:
case PM_RESTORE_PREPARE:
case PM_SUSPEND_PREPARE:
ret = tegra20_regulator_prepare_suspend(tegra, true);
break;
case PM_POST_HIBERNATION:
case PM_POST_RESTORE:
case PM_POST_SUSPEND:
ret = tegra20_regulator_prepare_suspend(tegra, false);
break;
}
if (ret)
pr_err("failed to prepare regulators: %d\n", ret);
return notifier_from_errno(ret);
}
static int tegra20_regulator_prepare_reboot(struct tegra_regulator_coupler *tegra,
bool sys_reboot_mode)
{
int err;
if (!tegra->core_rdev || !tegra->rtc_rdev || !tegra->cpu_rdev)
return 0;
WRITE_ONCE(tegra->sys_reboot_mode_req, true);
/*
* Some devices use CPU soft-reboot method and in this case we
* should ensure that voltages are sane for the reboot by restoring
* the minimum boot levels.
*/
err = regulator_sync_voltage_rdev(tegra->cpu_rdev);
if (err)
return err;
err = regulator_sync_voltage_rdev(tegra->core_rdev);
if (err)
return err;
WRITE_ONCE(tegra->sys_reboot_mode_req, sys_reboot_mode);
return 0;
}
static int tegra20_regulator_reboot(struct notifier_block *notifier,
unsigned long event, void *cmd)
{
struct tegra_regulator_coupler *tegra;
int ret;
if (event != SYS_RESTART)
return NOTIFY_DONE;
tegra = container_of(notifier, struct tegra_regulator_coupler,
reboot_notifier);
ret = tegra20_regulator_prepare_reboot(tegra, true);
return notifier_from_errno(ret);
}
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);
/*
* We don't expect regulators to be decoupled during reboot,
* this may race with the reboot handler and shouldn't ever
* happen in practice.
*/
if (WARN_ON_ONCE(system_state > SYSTEM_RUNNING))
return -EPERM;
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,
},
.reboot_notifier.notifier_call = tegra20_regulator_reboot,
.suspend_notifier.notifier_call = tegra20_regulator_suspend,
};
static int __init tegra_regulator_coupler_init(void)
{
int err;
if (!of_machine_is_compatible("nvidia,tegra20"))
return 0;
err = register_reboot_notifier(&tegra20_coupler.reboot_notifier);
WARN_ON(err);
err = register_pm_notifier(&tegra20_coupler.suspend_notifier);
WARN_ON(err);
return regulator_coupler_register(&tegra20_coupler.coupler);
}
arch_initcall(tegra_regulator_coupler_init);
Codebase Browser
linux