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Subject[RFC PATCH v1 5/6] soc/tegra: regulators: Add regulators coupler for Tegra20
Date
Add regulators coupler for Tegra20 SoC's that performs voltage balancing
of a coupled regulators and thus provides voltage scaling functionality.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
drivers/soc/tegra/Kconfig | 6 +
drivers/soc/tegra/Makefile | 1 +
drivers/soc/tegra/regulators-tegra20.c | 304 +++++++++++++++++++++++++
3 files changed, 311 insertions(+)
create mode 100644 drivers/soc/tegra/regulators-tegra20.c

diff --git a/drivers/soc/tegra/Kconfig b/drivers/soc/tegra/Kconfig
index a0b03443d8c1..545c0da2e069 100644
--- a/drivers/soc/tegra/Kconfig
+++ b/drivers/soc/tegra/Kconfig
@@ -133,3 +133,9 @@ config SOC_TEGRA_POWERGATE_BPMP
def_bool y
depends on PM_GENERIC_DOMAINS
depends on TEGRA_BPMP
+
+config SOC_TEGRA20_VOLTAGE_COUPLER
+ bool "Voltage scaling support for Tegra20 SoC's"
+ def_bool y
+ depends on ARCH_TEGRA_2x_SOC
+ depends on REGULATOR
diff --git a/drivers/soc/tegra/Makefile b/drivers/soc/tegra/Makefile
index 902759fe5f4d..9f0bdd53bef8 100644
--- a/drivers/soc/tegra/Makefile
+++ b/drivers/soc/tegra/Makefile
@@ -5,3 +5,4 @@ obj-y += common.o
obj-$(CONFIG_SOC_TEGRA_FLOWCTRL) += flowctrl.o
obj-$(CONFIG_SOC_TEGRA_PMC) += pmc.o
obj-$(CONFIG_SOC_TEGRA_POWERGATE_BPMP) += powergate-bpmp.o
+obj-$(CONFIG_SOC_TEGRA20_VOLTAGE_COUPLER) += regulators-tegra20.o
diff --git a/drivers/soc/tegra/regulators-tegra20.c b/drivers/soc/tegra/regulators-tegra20.c
new file mode 100644
index 000000000000..3f005b804af3
--- /dev/null
+++ b/drivers/soc/tegra/regulators-tegra20.c
@@ -0,0 +1,304 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Voltage regulators coupling resolver for NVIDIA Tegra20
+ *
+ * Author: Dmitry Osipenko <digetx@gmail.com>
+ */
+
+#define pr_fmt(fmt) "tegra voltage-coupler: " fmt
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+
+struct tegra_regulators_coupler {
+ struct regulators_coupler coupler;
+ int core_min_uV;
+};
+
+static const char * const cpu_names[] = {
+ "vdd_sys_sm0,vdd_core",
+ "+1.0vs_sm1,vdd_cpu",
+ "vdd_sm1,vdd_cpu",
+ "VDD_CPU_1.0V",
+ "vdd_cpu",
+};
+
+static const char * const core_names[] = {
+ "vdd_sys_sm1,vdd_cpu",
+ "+1.2vs_sm0,vdd_core",
+ "vdd_sm0,vdd_core",
+ "VDD_CORE_1.2V",
+ "vdd_core",
+};
+
+static const char * const rtc_names[] = {
+ "+1.2vs_ldo2,vdd_rtc",
+ "vdd_ldo2,vdd_rtc",
+ "VDD_RTC_1.2V",
+ "vdd_rtc",
+};
+
+static inline struct tegra_regulators_coupler *
+to_tegra_coupler(struct regulators_coupler *coupler)
+{
+ return container_of(coupler, struct tegra_regulators_coupler, coupler);
+}
+
+static int tegra20_core_limit(struct tegra_regulators_coupler *tegra,
+ struct regulator_dev *core_rdev,
+ struct regulator_dev *rtc_rdev)
+{
+ int core_min_uV;
+
+ if (tegra->core_min_uV > 0)
+ return tegra->core_min_uV;
+
+ core_min_uV = regulator_get_voltage_rdev(core_rdev);
+ if (core_min_uV > 0) {
+ pr_info("core minimum voltage limited to %duV\n", core_min_uV);
+ tegra->core_min_uV = core_min_uV;
+ }
+
+ return core_min_uV;
+}
+
+static int tegra20_core_rtc_update(struct tegra_regulators_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 core_uV;
+ int rtc_uV;
+ int err;
+
+ /*
+ * The core voltage scaling is currently not hooked up in drivers,
+ * hence we will limit the minimum core voltage to the initial value.
+ * This should be good enough for the time being.
+ */
+ core_min_uV = tegra20_core_limit(tegra, core_rdev, rtc_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_min_uV = max(cpu_min_uV + 125000, core_min_uV);
+ if (core_min_uV > core_max_uV)
+ return -EINVAL;
+
+ core_uV = regulator_get_voltage_rdev(core_rdev);
+ if (core_uV < 0)
+ return core_uV;
+
+ 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 - 150000);
+
+ 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 + 150000, core_min_uV);
+ core_target_uV = min(rtc_uV + 150000, core_target_uV);
+ } else {
+ core_target_uV = max(core_uV - 150000, core_min_uV);
+ core_target_uV = max(rtc_uV - 150000, 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 + 150000, rtc_min_uV);
+ rtc_target_uV = min(core_uV + 150000, rtc_target_uV);
+ } else {
+ rtc_target_uV = max(rtc_uV - 150000, rtc_min_uV);
+ rtc_target_uV = max(core_uV - 150000, 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_regulators_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_regulators_coupler *tegra,
+ struct regulator_dev *cpu_rdev,
+ struct regulator_dev *core_rdev,
+ struct regulator_dev *rtc_rdev)
+{
+ int cpu_min_uV = 0;
+ int cpu_max_uV = INT_MAX;
+ 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;
+
+ cpu_uV = regulator_get_voltage_rdev(cpu_rdev);
+ if (cpu_uV < 0)
+ return 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 struct regulator_dev *lookup_rdev(struct regulator_dev *rdev,
+ const char * const *names,
+ unsigned int num_names)
+{
+ struct coupling_desc *c_desc = &rdev->coupling_desc;
+ unsigned int i, k;
+
+ for (i = 0; i < num_names; i++) {
+ if (!strcmp(names[i], rdev_get_name(rdev)))
+ return rdev;
+ }
+
+ for (k = 0; k < c_desc->n_coupled; k++) {
+ rdev = c_desc->coupled_rdevs[k];
+
+ for (i = 0; i < num_names; i++) {
+ if (!strcmp(names[i], rdev_get_name(rdev)))
+ return rdev;
+ }
+ }
+
+ pr_err_once("%s: failed for %s\n", __func__, rdev_get_name(rdev));
+
+ for (i = 0; i < num_names; i++)
+ pr_err_once("%s: entry%u: %s\n", __func__, i, names[i]);
+
+ return NULL;
+}
+
+static int tegra20_regulator_balance_voltage(struct regulators_coupler *coupler,
+ struct regulator_dev *rdev,
+ suspend_state_t state)
+{
+ struct tegra_regulators_coupler *tegra = to_tegra_coupler(coupler);
+ struct regulator_dev *core_rdev;
+ struct regulator_dev *cpu_rdev;
+ struct regulator_dev *rtc_rdev;
+
+ core_rdev = lookup_rdev(rdev, core_names, ARRAY_SIZE(core_names));
+ cpu_rdev = lookup_rdev(rdev, cpu_names, ARRAY_SIZE(cpu_names));
+ rtc_rdev = lookup_rdev(rdev, rtc_names, ARRAY_SIZE(rtc_names));
+
+ if (!core_rdev || !cpu_rdev || !rtc_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("driving %s voltage not permitted\n", rdev_get_name(rtc_rdev));
+
+ return -EPERM;
+}
+
+static struct tegra_regulators_coupler tegra20_coupler = {
+ .coupler = {
+ .balance_voltage = tegra20_regulator_balance_voltage,
+ },
+};
+
+static int __init tegra_regulators_coupler_init(void)
+{
+ if (!of_machine_is_compatible("nvidia,tegra20"))
+ return 0;
+
+ return regulators_coupler_register(&tegra20_coupler.coupler);
+}
+arch_initcall(tegra_regulators_coupler_init);
--
2.21.0
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