--- /dev/null
+/*
+ * Copyright (c) 2015 Linaro Ltd.
+ * Author: Pi-Cheng Chen <pi-cheng.chen@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk.h>
+#include <linux/cpu.h>
+#include <linux/cpu_cooling.h>
+#include <linux/cpufreq.h>
+#include <linux/cpumask.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm_opp.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+#include <linux/thermal.h>
+
+#define MIN_VOLT_SHIFT (100000)
+#define MAX_VOLT_SHIFT (200000)
+#define MAX_VOLT_LIMIT (1150000)
+#define VOLT_TOL (10000)
+
+/*
+ * The struct mtk_cpu_dvfs_info holds necessary information for doing CPU DVFS
+ * on each CPU power/clock domain of Mediatek SoCs. Each CPU cluster in
+ * Mediatek SoCs has two voltage inputs, Vproc and Vsram. In some cases the two
+ * voltage inputs need to be controlled under a hardware limitation:
+ * 100mV < Vsram - Vproc < 200mV
+ *
+ * When scaling the clock frequency of a CPU clock domain, the clock source
+ * needs to be switched to another stable PLL clock temporarily until
+ * the original PLL becomes stable at target frequency.
+ */
+struct mtk_cpu_dvfs_info {
+ struct device *cpu_dev;
+ struct regulator *proc_reg;
+ struct regulator *sram_reg;
+ struct clk *cpu_clk;
+ struct clk *inter_clk;
+ struct thermal_cooling_device *cdev;
+ int intermediate_voltage;
+ bool need_voltage_tracking;
+};
+
+static int mtk_cpufreq_voltage_tracking(struct mtk_cpu_dvfs_info *info,
+ int new_vproc)
+{
+ struct regulator *proc_reg = info->proc_reg;
+ struct regulator *sram_reg = info->sram_reg;
+ int old_vproc, old_vsram, new_vsram, vsram, vproc, ret;
+
+ old_vproc = regulator_get_voltage(proc_reg);
+ old_vsram = regulator_get_voltage(sram_reg);
+ /* Vsram should not exceed the maximum allowed voltage of SoC. */
+ new_vsram = min(new_vproc + MIN_VOLT_SHIFT, MAX_VOLT_LIMIT);
+
+ if (old_vproc < new_vproc) {
+ /*
+ * When scaling up voltages, Vsram and Vproc scale up step
+ * by step. At each step, set Vsram to (Vproc + 200mV) first,
+ * then set Vproc to (Vsram - 100mV).
+ * Keep doing it until Vsram and Vproc hit target voltages.
+ */
+ do {
+ old_vsram = regulator_get_voltage(sram_reg);
+ old_vproc = regulator_get_voltage(proc_reg);
+
+ vsram = min(new_vsram, old_vproc + MAX_VOLT_SHIFT);
+
+ if (vsram + VOLT_TOL >= MAX_VOLT_LIMIT) {
+ vsram = MAX_VOLT_LIMIT;
+
+ /*
+ * If the target Vsram hits the maximum voltage,
+ * try to set the exact voltage value first.
+ */
+ ret = regulator_set_voltage(sram_reg, vsram,
+ vsram);
+ if (ret)
+ ret = regulator_set_voltage(sram_reg,
+ vsram - VOLT_TOL,
+ vsram);
+
+ vproc = new_vproc;
+ } else {
+ ret = regulator_set_voltage(sram_reg, vsram,
+ vsram + VOLT_TOL);
+
+ vproc = vsram - MIN_VOLT_SHIFT;
+ }
+ if (ret)
+ return ret;
+
+ ret = regulator_set_voltage(proc_reg, vproc,
+ vproc + VOLT_TOL);
+ if (ret) {
+ regulator_set_voltage(sram_reg, old_vsram,
+ old_vsram);
+ return ret;
+ }
+ } while (vproc < new_vproc || vsram < new_vsram);
+ } else if (old_vproc > new_vproc) {
+ /*
+ * When scaling down voltages, Vsram and Vproc scale down step
+ * by step. At each step, set Vproc to (Vsram - 200mV) first,
+ * then set Vproc to (Vproc + 100mV).
+ * Keep doing it until Vsram and Vproc hit target voltages.
+ */
+ do {
+ old_vproc = regulator_get_voltage(proc_reg);
+ old_vsram = regulator_get_voltage(sram_reg);
+
+ vproc = max(new_vproc, old_vsram - MAX_VOLT_SHIFT);
+ ret = regulator_set_voltage(proc_reg, vproc,
+ vproc + VOLT_TOL);
+ if (ret)
+ return ret;
+
+ if (vproc == new_vproc)
+ vsram = new_vsram;
+ else
+ vsram = max(new_vsram, vproc + MIN_VOLT_SHIFT);
+
+ if (vsram + VOLT_TOL >= MAX_VOLT_LIMIT) {
+ vsram = MAX_VOLT_LIMIT;
+
+ /*
+ * If the target Vsram hits the maximum voltage,
+ * try to set the exact voltage value first.
+ */
+ ret = regulator_set_voltage(sram_reg, vsram,
+ vsram);
+ if (ret)
+ ret = regulator_set_voltage(sram_reg,
+ vsram - VOLT_TOL,
+ vsram);
+ } else {
+ ret = regulator_set_voltage(sram_reg, vsram,
+ vsram + VOLT_TOL);
+ }
+
+ if (ret) {
+ regulator_set_voltage(proc_reg, old_vproc,
+ old_vproc);
+ return ret;
+ }
+ } while (vproc > new_vproc + VOLT_TOL ||
+ vsram > new_vsram + VOLT_TOL);
+ }
+
+ return 0;
+}
+
+static int mtk_cpufreq_set_voltage(struct mtk_cpu_dvfs_info *info, int vproc)
+{
+ if (info->need_voltage_tracking)
+ return mtk_cpufreq_voltage_tracking(info, vproc);
+ else
+ return regulator_set_voltage(info->proc_reg, vproc,
+ vproc + VOLT_TOL);
+}
+
+static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
+ unsigned int index)
+{
+ struct cpufreq_frequency_table *freq_table = policy->freq_table;
+ struct clk *cpu_clk = policy->clk;
+ struct clk *armpll = clk_get_parent(cpu_clk);
+ struct mtk_cpu_dvfs_info *info = policy->driver_data;
+ struct device *cpu_dev = info->cpu_dev;
+ struct dev_pm_opp *opp;
+ long freq_hz, old_freq_hz;
+ int vproc, old_vproc, inter_vproc, target_vproc, ret;
+
+ inter_vproc = info->intermediate_voltage;
+
+ old_freq_hz = clk_get_rate(cpu_clk);
+ old_vproc = regulator_get_voltage(info->proc_reg);
+
+ freq_hz = freq_table[index].frequency * 1000;
+
+ rcu_read_lock();
+ opp = dev_pm_opp_find_freq_ceil(cpu_dev, &freq_hz);
+ if (IS_ERR(opp)) {
+ rcu_read_unlock();
+ pr_err("cpu%d: failed to find OPP for %ld\n",
+ policy->cpu, freq_hz);
+ return PTR_ERR(opp);
+ }
+ vproc = dev_pm_opp_get_voltage(opp);
+ rcu_read_unlock();
+
+ /*
+ * If the new voltage or the intermediate voltage is higher than the
+ * current voltage, scale up voltage first.
+ */
+ target_vproc = (inter_vproc > vproc) ? inter_vproc : vproc;
+ if (old_vproc < target_vproc) {
+ ret = mtk_cpufreq_set_voltage(info, target_vproc);
+ if (ret) {
+ pr_err("cpu%d: failed to scale up voltage!\n",
+ policy->cpu);
+ mtk_cpufreq_set_voltage(info, old_vproc);
+ return ret;
+ }
+ }
+
+ /* Reparent the CPU clock to intermediate clock. */
+ ret = clk_set_parent(cpu_clk, info->inter_clk);
+ if (ret) {
+ pr_err("cpu%d: failed to re-parent cpu clock!\n",
+ policy->cpu);
+ mtk_cpufreq_set_voltage(info, old_vproc);
+ WARN_ON(1);
+ return ret;
+ }
+
+ /* Set the original PLL to target rate. */
+ ret = clk_set_rate(armpll, freq_hz);
+ if (ret) {
+ pr_err("cpu%d: failed to scale cpu clock rate!\n",
+ policy->cpu);
+ clk_set_parent(cpu_clk, armpll);
+ mtk_cpufreq_set_voltage(info, old_vproc);
+ return ret;
+ }
+
+ /* Set parent of CPU clock back to the original PLL. */
+ ret = clk_set_parent(cpu_clk, armpll);
+ if (ret) {
+ pr_err("cpu%d: failed to re-parent cpu clock!\n",
+ policy->cpu);
+ mtk_cpufreq_set_voltage(info, inter_vproc);
+ WARN_ON(1);
+ return ret;
+ }
+
+ /*
+ * If the new voltage is lower than the intermediate voltage or the
+ * original voltage, scale down to the new voltage.
+ */
+ if (vproc < inter_vproc || vproc < old_vproc) {
+ ret = mtk_cpufreq_set_voltage(info, vproc);
+ if (ret) {
+ pr_err("cpu%d: failed to scale down voltage!\n",
+ policy->cpu);
+ clk_set_parent(cpu_clk, info->inter_clk);
+ clk_set_rate(armpll, old_freq_hz);
+ clk_set_parent(cpu_clk, armpll);
+ return ret;
+ }
+ }
+
+ return 0;
+}
+
+static void mtk_cpufreq_ready(struct cpufreq_policy *policy)
+{
+ struct mtk_cpu_dvfs_info *info = policy->driver_data;
+ struct device_node *np = of_node_get(info->cpu_dev->of_node);
+
+ if (WARN_ON(!np))
+ return;
+
+ if (of_find_property(np, "#cooling-cells", NULL)) {
+ info->cdev = of_cpufreq_cooling_register(np,
+ policy->related_cpus);
+
+ if (IS_ERR(info->cdev)) {
+ dev_err(info->cpu_dev,
+ "running cpufreq without cooling device: %ld\n",
+ PTR_ERR(info->cdev));
+
+ info->cdev = NULL;
+ }
+ }
+
+ of_node_put(np);
+}
+
+static int mtk_cpu_dvfs_info_init(struct mtk_cpu_dvfs_info *info, int cpu)
+{
+ struct device *cpu_dev;
+ struct regulator *proc_reg = ERR_PTR(-ENODEV);
+ struct regulator *sram_reg = ERR_PTR(-ENODEV);
+ struct clk *cpu_clk = ERR_PTR(-ENODEV);
+ struct clk *inter_clk = ERR_PTR(-ENODEV);
+ struct dev_pm_opp *opp;
+ unsigned long rate;
+ int ret;
+
+ cpu_dev = get_cpu_device(cpu);
+ if (!cpu_dev) {
+ pr_err("failed to get cpu%d device\n", cpu);
+ return -ENODEV;
+ }
+
+ cpu_clk = clk_get(cpu_dev, "cpu");
+ if (IS_ERR(cpu_clk)) {
+ if (PTR_ERR(cpu_clk) == -EPROBE_DEFER)
+ pr_warn("cpu clk for cpu%d not ready, retry.\n", cpu);
+ else
+ pr_err("failed to get cpu clk for cpu%d\n", cpu);
+
+ ret = PTR_ERR(cpu_clk);
+ return ret;
+ }
+
+ inter_clk = clk_get(cpu_dev, "intermediate");
+ if (IS_ERR(inter_clk)) {
+ if (PTR_ERR(inter_clk) == -EPROBE_DEFER)
+ pr_warn("intermediate clk for cpu%d not ready, retry.\n",
+ cpu);
+ else
+ pr_err("failed to get intermediate clk for cpu%d\n",
+ cpu);
+
+ ret = PTR_ERR(inter_clk);
+ goto out_free_resources;
+ }
+
+ proc_reg = regulator_get_exclusive(cpu_dev, "proc");
+ if (IS_ERR(proc_reg)) {
+ if (PTR_ERR(proc_reg) == -EPROBE_DEFER)
+ pr_warn("proc regulator for cpu%d not ready, retry.\n",
+ cpu);
+ else
+ pr_err("failed to get proc regulator for cpu%d\n",
+ cpu);
+
+ ret = PTR_ERR(proc_reg);
+ goto out_free_resources;
+ }
+
+ /* Both presence and absence of sram regulator are valid cases. */
+ sram_reg = regulator_get_exclusive(cpu_dev, "sram");
+
+ ret = dev_pm_opp_of_add_table(cpu_dev);
+ if (ret) {
+ pr_warn("no OPP table for cpu%d\n", cpu);
+ goto out_free_resources;
+ }
+
+ /* Search a safe voltage for intermediate frequency. */
+ rate = clk_get_rate(inter_clk);
+ rcu_read_lock();
+ opp = dev_pm_opp_find_freq_ceil(cpu_dev, &rate);
+ if (IS_ERR(opp)) {
+ rcu_read_unlock();
+ pr_err("failed to get intermediate opp for cpu%d\n", cpu);
+ ret = PTR_ERR(opp);
+ goto out_free_opp_table;
+ }
+ info->intermediate_voltage = dev_pm_opp_get_voltage(opp);
+ rcu_read_unlock();
+
+ info->cpu_dev = cpu_dev;
+ info->proc_reg = proc_reg;
+ info->sram_reg = IS_ERR(sram_reg) ? NULL : sram_reg;
+ info->cpu_clk = cpu_clk;
+ info->inter_clk = inter_clk;
+
+ /*
+ * If SRAM regulator is present, software "voltage tracking" is needed
+ * for this CPU power domain.
+ */
+ info->need_voltage_tracking = !IS_ERR(sram_reg);
+
+ return 0;
+
+out_free_opp_table:
+ dev_pm_opp_of_remove_table(cpu_dev);
+
+out_free_resources:
+ if (!IS_ERR(proc_reg))
+ regulator_put(proc_reg);
+ if (!IS_ERR(sram_reg))
+ regulator_put(sram_reg);
+ if (!IS_ERR(cpu_clk))
+ clk_put(cpu_clk);
+ if (!IS_ERR(inter_clk))
+ clk_put(inter_clk);
+
+ return ret;
+}
+
+static void mtk_cpu_dvfs_info_release(struct mtk_cpu_dvfs_info *info)
+{
+ if (!IS_ERR(info->proc_reg))
+ regulator_put(info->proc_reg);
+ if (!IS_ERR(info->sram_reg))
+ regulator_put(info->sram_reg);
+ if (!IS_ERR(info->cpu_clk))
+ clk_put(info->cpu_clk);
+ if (!IS_ERR(info->inter_clk))
+ clk_put(info->inter_clk);
+
+ dev_pm_opp_of_remove_table(info->cpu_dev);
+}
+
+static int mtk_cpufreq_init(struct cpufreq_policy *policy)
+{
+ struct mtk_cpu_dvfs_info *info;
+ struct cpufreq_frequency_table *freq_table;
+ int ret;
+
+ info = kzalloc(sizeof(*info), GFP_KERNEL);
+ if (!info)
+ return -ENOMEM;
+
+ ret = mtk_cpu_dvfs_info_init(info, policy->cpu);
+ if (ret) {
+ pr_err("%s failed to initialize dvfs info for cpu%d\n",
+ __func__, policy->cpu);
+ goto out_free_dvfs_info;
+ }
+
+ ret = dev_pm_opp_init_cpufreq_table(info->cpu_dev, &freq_table);
+ if (ret) {
+ pr_err("failed to init cpufreq table for cpu%d: %d\n",
+ policy->cpu, ret);
+ goto out_release_dvfs_info;
+ }
+
+ ret = cpufreq_table_validate_and_show(policy, freq_table);
+ if (ret) {
+ pr_err("%s: invalid frequency table: %d\n", __func__, ret);
+ goto out_free_cpufreq_table;
+ }
+
+ /* CPUs in the same cluster share a clock and power domain. */
+ cpumask_copy(policy->cpus, &cpu_topology[policy->cpu].core_sibling);
+ policy->driver_data = info;
+ policy->clk = info->cpu_clk;
+
+ return 0;
+
+out_free_cpufreq_table:
+ dev_pm_opp_free_cpufreq_table(info->cpu_dev, &freq_table);
+
+out_release_dvfs_info:
+ mtk_cpu_dvfs_info_release(info);
+
+out_free_dvfs_info:
+ kfree(info);
+
+ return ret;
+}
+
+static int mtk_cpufreq_exit(struct cpufreq_policy *policy)
+{
+ struct mtk_cpu_dvfs_info *info = policy->driver_data;
+
+ cpufreq_cooling_unregister(info->cdev);
+ dev_pm_opp_free_cpufreq_table(info->cpu_dev, &policy->freq_table);
+ mtk_cpu_dvfs_info_release(info);
+ kfree(info);
+
+ return 0;
+}
+
+static struct cpufreq_driver mt8173_cpufreq_driver = {
+ .flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+ .verify = cpufreq_generic_frequency_table_verify,
+ .target_index = mtk_cpufreq_set_target,
+ .get = cpufreq_generic_get,
+ .init = mtk_cpufreq_init,
+ .exit = mtk_cpufreq_exit,
+ .ready = mtk_cpufreq_ready,
+ .name = "mtk-cpufreq",
+ .attr = cpufreq_generic_attr,
+};
+
+static int mt8173_cpufreq_probe(struct platform_device *pdev)
+{
+ int ret;
+
+ ret = cpufreq_register_driver(&mt8173_cpufreq_driver);
+ if (ret)
+ pr_err("failed to register mtk cpufreq driver\n");
+
+ return ret;
+}
+
+static struct platform_driver mt8173_cpufreq_platdrv = {
+ .driver = {
+ .name = "mt8173-cpufreq",
+ },
+ .probe = mt8173_cpufreq_probe,
+};
+
+static int mt8173_cpufreq_driver_init(void)
+{
+ struct platform_device *pdev;
+ int err;
+
+ if (!of_machine_is_compatible("mediatek,mt8173"))
+ return -ENODEV;
+
+ err = platform_driver_register(&mt8173_cpufreq_platdrv);
+ if (err)
+ return err;
+
+ /*
+ * Since there's no place to hold device registration code and no
+ * device tree based way to match cpufreq driver yet, both the driver
+ * and the device registration codes are put here to handle defer
+ * probing.
+ */
+ pdev = platform_device_register_simple("mt8173-cpufreq", -1, NULL, 0);
+ if (IS_ERR(pdev)) {
+ pr_err("failed to register mtk-cpufreq platform device\n");
+ return PTR_ERR(pdev);
+ }
+
+ return 0;
+}
+device_initcall(mt8173_cpufreq_driver_init);
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