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path: root/drivers/soc/tegra/regulators-tegra20.c
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Diffstat (limited to 'drivers/soc/tegra/regulators-tegra20.c')
-rw-r--r--drivers/soc/tegra/regulators-tegra20.c365
1 files changed, 365 insertions, 0 deletions
diff --git a/drivers/soc/tegra/regulators-tegra20.c b/drivers/soc/tegra/regulators-tegra20.c
new file mode 100644
index 000000000000..ea0eede48802
--- /dev/null
+++ b/drivers/soc/tegra/regulators-tegra20.c
@@ -0,0 +1,365 @@
+// 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);
+ }
+
+ 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);