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Subject[RFC/PATCH 10/12] cpufreq: Add a cpufreq-krait based on cpufreq-cpu0
Date
Krait processors have individual clocks for each CPU that can
scale independently from one another. cpufreq-cpu0 is fairly
close to this, but assumes that there is only one clock for all
CPUs. Add a driver to support the Krait configuration.

TODO: Merge into cpufreq-cpu0? Or make generic?

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
---
drivers/cpufreq/Kconfig | 13 +++
drivers/cpufreq/Makefile | 1 +
drivers/cpufreq/cpufreq-krait.c | 190 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 204 insertions(+)
create mode 100644 drivers/cpufreq/cpufreq-krait.c

diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
index ffe350f86bca..e9826c85a777 100644
--- a/drivers/cpufreq/Kconfig
+++ b/drivers/cpufreq/Kconfig
@@ -196,6 +196,19 @@ config GENERIC_CPUFREQ_CPU0

If in doubt, say N.

+config GENERIC_CPUFREQ_KRAIT
+ tristate "Krait cpufreq driver"
+ depends on HAVE_CLK && OF
+ # if CPU_THERMAL is on and THERMAL=m, CPU0 cannot be =y:
+ depends on !CPU_THERMAL || THERMAL
+ select PM_OPP
+ help
+ This adds a generic cpufreq driver for CPU0 frequency management.
+ It supports both uniprocessor (UP) and symmetric multiprocessor (SMP)
+ systems which share clock and voltage across all CPUs.
+
+ If in doubt, say N.
+
menu "x86 CPU frequency scaling drivers"
depends on X86
source "drivers/cpufreq/Kconfig.x86"
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index 738c8b7b17dc..f5c9f68dcc0f 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_CPU_FREQ_GOV_CONSERVATIVE) += cpufreq_conservative.o
obj-$(CONFIG_CPU_FREQ_GOV_COMMON) += cpufreq_governor.o

obj-$(CONFIG_GENERIC_CPUFREQ_CPU0) += cpufreq-cpu0.o
+obj-$(CONFIG_CPUFREQ_KRAIT) += cpufreq-krait.o

##################################################################################
# x86 drivers.
diff --git a/drivers/cpufreq/cpufreq-krait.c b/drivers/cpufreq/cpufreq-krait.c
new file mode 100644
index 000000000000..7b38b9c948e5
--- /dev/null
+++ b/drivers/cpufreq/cpufreq-krait.c
@@ -0,0 +1,190 @@
+/*
+ * Copyright (C) 2012 Freescale Semiconductor, Inc.
+ * Copyright (c) 2014, The Linux Foundation. All rights reserved.
+ *
+ * The OPP code in function krait_set_target() is reused from
+ * drivers/cpufreq/omap-cpufreq.c
+ *
+ * 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.
+ */
+
+#include <linux/clk.h>
+#include <linux/cpu.h>
+#include <linux/cpu_cooling.h>
+#include <linux/cpufreq.h>
+#include <linux/cpumask.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/pm_opp.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/thermal.h>
+
+static unsigned int transition_latency;
+
+static struct device *cpu_dev;
+static DEFINE_PER_CPU(struct clk *, krait_cpu_clks);
+static struct cpufreq_frequency_table *freq_table;
+static struct thermal_cooling_device *cdev;
+
+static int krait_set_target(struct cpufreq_policy *policy, unsigned int index)
+{
+ unsigned long volt = 0, volt_old = 0;
+ unsigned int old_freq, new_freq;
+ long freq_Hz, freq_exact;
+ int ret;
+ struct clk *cpu_clk;
+
+ cpu_clk = per_cpu(krait_cpu_clks, policy->cpu);
+
+ freq_Hz = clk_round_rate(cpu_clk, freq_table[index].frequency * 1000);
+ if (freq_Hz <= 0)
+ freq_Hz = freq_table[index].frequency * 1000;
+
+ freq_exact = freq_Hz;
+ new_freq = freq_Hz / 1000;
+ old_freq = clk_get_rate(cpu_clk) / 1000;
+
+ pr_debug("%u MHz, %ld mV --> %u MHz, %ld mV\n",
+ old_freq / 1000, volt_old ? volt_old / 1000 : -1,
+ new_freq / 1000, volt ? volt / 1000 : -1);
+
+ ret = clk_set_rate(cpu_clk, freq_exact);
+ if (ret)
+ pr_err("failed to set clock rate: %d\n", ret);
+
+ return ret;
+}
+
+static int krait_cpufreq_init(struct cpufreq_policy *policy)
+{
+ int ret;
+
+ policy->clk = per_cpu(krait_cpu_clks, policy->cpu);
+
+ ret = cpufreq_table_validate_and_show(policy, freq_table);
+ if (ret) {
+ pr_err("%s: invalid frequency table: %d\n", __func__, ret);
+ return ret;
+ }
+
+ policy->cpuinfo.transition_latency = transition_latency;
+
+ return 0;
+}
+
+static struct cpufreq_driver krait_cpufreq_driver = {
+ .flags = CPUFREQ_STICKY,
+ .verify = cpufreq_generic_frequency_table_verify,
+ .target_index = krait_set_target,
+ .get = cpufreq_generic_get,
+ .init = krait_cpufreq_init,
+ .name = "generic_krait",
+ .attr = cpufreq_generic_attr,
+};
+
+static int krait_cpufreq_probe(struct platform_device *pdev)
+{
+ struct device_node *np;
+ int ret;
+ unsigned int cpu;
+ struct device *dev;
+ struct clk *clk;
+
+ cpu_dev = get_cpu_device(0);
+ if (!cpu_dev) {
+ pr_err("failed to get krait device\n");
+ return -ENODEV;
+ }
+
+ np = of_node_get(cpu_dev->of_node);
+ if (!np) {
+ pr_err("failed to find krait node\n");
+ return -ENOENT;
+ }
+
+ for_each_possible_cpu(cpu) {
+ dev = get_cpu_device(cpu);
+ if (!dev) {
+ pr_err("failed to get krait device\n");
+ ret = -ENOENT;
+ goto out_put_node;
+ }
+ per_cpu(krait_cpu_clks, cpu) = clk = devm_clk_get(dev, NULL);
+ if (IS_ERR(clk)) {
+ ret = PTR_ERR(clk);
+ goto out_put_node;
+ }
+ }
+
+ ret = of_init_opp_table(cpu_dev);
+ if (ret) {
+ pr_err("failed to init OPP table: %d\n", ret);
+ goto out_put_node;
+ }
+
+ ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
+ if (ret) {
+ pr_err("failed to init cpufreq table: %d\n", ret);
+ goto out_put_node;
+ }
+
+ if (of_property_read_u32(np, "clock-latency", &transition_latency))
+ transition_latency = CPUFREQ_ETERNAL;
+
+ ret = cpufreq_register_driver(&krait_cpufreq_driver);
+ if (ret) {
+ pr_err("failed register driver: %d\n", ret);
+ goto out_free_table;
+ }
+ of_node_put(np);
+
+ /*
+ * For now, just loading the cooling device;
+ * thermal DT code takes care of matching them.
+ */
+ for_each_possible_cpu(cpu) {
+ dev = get_cpu_device(cpu);
+ np = of_node_get(dev->of_node);
+ if (of_find_property(np, "#cooling-cells", NULL)) {
+ cdev = of_cpufreq_cooling_register(np, cpumask_of(cpu));
+ if (IS_ERR(cdev))
+ pr_err("running cpufreq without cooling device: %ld\n",
+ PTR_ERR(cdev));
+ }
+ of_node_put(np);
+ }
+
+ return 0;
+
+out_free_table:
+ dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
+out_put_node:
+ of_node_put(np);
+ return ret;
+}
+
+static int krait_cpufreq_remove(struct platform_device *pdev)
+{
+ cpufreq_cooling_unregister(cdev);
+ cpufreq_unregister_driver(&krait_cpufreq_driver);
+ dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
+
+ return 0;
+}
+
+static struct platform_driver krait_cpufreq_platdrv = {
+ .driver = {
+ .name = "cpufreq-krait",
+ .owner = THIS_MODULE,
+ },
+ .probe = krait_cpufreq_probe,
+ .remove = krait_cpufreq_remove,
+};
+module_platform_driver(krait_cpufreq_platdrv);
+
+MODULE_DESCRIPTION("Krait CPUfreq driver");
+MODULE_LICENSE("GPL v2");
--
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