[PATCH V3 4/7] cpufreq: add generic cpufreq driver
Richard Zhao
richard.zhao at linaro.org
Sun Dec 18 22:21:40 EST 2011
It support single core and multi-core ARM SoCs. But currently it assume
all cores share the same frequency and voltage.
Signed-off-by: Richard Zhao <richard.zhao at linaro.org>
---
.../devicetree/bindings/cpufreq/generic-cpufreq | 7 +
drivers/cpufreq/Kconfig | 8 +
drivers/cpufreq/Makefile | 2 +
drivers/cpufreq/generic-cpufreq.c | 251 ++++++++++++++++++++
4 files changed, 268 insertions(+), 0 deletions(-)
create mode 100644 Documentation/devicetree/bindings/cpufreq/generic-cpufreq
create mode 100644 drivers/cpufreq/generic-cpufreq.c
diff --git a/Documentation/devicetree/bindings/cpufreq/generic-cpufreq b/Documentation/devicetree/bindings/cpufreq/generic-cpufreq
new file mode 100644
index 0000000..15dd780
--- /dev/null
+++ b/Documentation/devicetree/bindings/cpufreq/generic-cpufreq
@@ -0,0 +1,7 @@
+Generic cpufreq driver
+
+Required properties in /cpus/cpu at 0:
+- compatible : "generic-cpufreq"
+- cpu-freqs : cpu frequency points it support
+- cpu-volts : cpu voltages required by the frequency point at the same index
+- trans-latency : transition_latency
diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
index e24a2a1..216eecd 100644
--- a/drivers/cpufreq/Kconfig
+++ b/drivers/cpufreq/Kconfig
@@ -179,6 +179,14 @@ config CPU_FREQ_GOV_CONSERVATIVE
If in doubt, say N.
+config GENERIC_CPUFREQ_DRIVER
+ bool "Generic cpufreq driver using clock/regulator/devicetree"
+ help
+ This adds generic CPUFreq driver. It assumes all
+ cores of the CPU share the same clock and voltage.
+
+ 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 ce75fcb..2dbdab1 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -13,6 +13,8 @@ obj-$(CONFIG_CPU_FREQ_GOV_CONSERVATIVE) += cpufreq_conservative.o
# CPUfreq cross-arch helpers
obj-$(CONFIG_CPU_FREQ_TABLE) += freq_table.o
+obj-$(CONFIG_GENERIC_CPUFREQ_DRIVER) += generic-cpufreq.o
+
##################################################################################
# x86 drivers.
# Link order matters. K8 is preferred to ACPI because of firmware bugs in early
diff --git a/drivers/cpufreq/generic-cpufreq.c b/drivers/cpufreq/generic-cpufreq.c
new file mode 100644
index 0000000..781bb9b
--- /dev/null
+++ b/drivers/cpufreq/generic-cpufreq.c
@@ -0,0 +1,251 @@
+/*
+ * Copyright (C) 2011 Freescale Semiconductor, Inc.
+ */
+
+/*
+ * The code contained herein is licensed under the GNU General Public
+ * License. You may obtain a copy of the GNU General Public License
+ * Version 2 or later at the following locations:
+ *
+ * http://www.opensource.org/licenses/gpl-license.html
+ * http://www.gnu.org/copyleft/gpl.html
+ */
+
+#include <linux/module.h>
+#include <linux/cpufreq.h>
+#include <linux/clk.h>
+#include <linux/regulator/consumer.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+
+static u32 *cpu_freqs; /* HZ */
+static u32 *cpu_volts; /* uV */
+static u32 trans_latency; /* ns */
+static int cpu_op_nr;
+
+static struct clk *cpu_clk;
+static struct regulator *cpu_reg;
+static struct cpufreq_frequency_table *freq_table;
+
+static int set_cpu_freq(unsigned long freq, int index, int higher)
+{
+ int ret = 0;
+
+ if (higher && cpu_reg)
+ regulator_set_voltage(cpu_reg,
+ cpu_volts[index], cpu_volts[index]);
+
+ ret = clk_set_rate(cpu_clk, freq);
+ if (ret != 0) {
+ pr_err("generic-cpufreq: cannot set CPU clock rate\n");
+ return ret;
+ }
+
+ if (!higher && cpu_reg)
+ regulator_set_voltage(cpu_reg,
+ cpu_volts[index], cpu_volts[index]);
+
+ return ret;
+}
+
+static int generic_verify_speed(struct cpufreq_policy *policy)
+{
+ return cpufreq_frequency_table_verify(policy, freq_table);
+}
+
+static unsigned int generic_get_speed(unsigned int cpu)
+{
+ return clk_get_rate(cpu_clk) / 1000;
+}
+
+static int generic_set_target(struct cpufreq_policy *policy,
+ unsigned int target_freq, unsigned int relation)
+{
+ struct cpufreq_freqs freqs;
+ unsigned long freq_Hz;
+ int cpu;
+ int ret = 0;
+ unsigned int index;
+
+ cpufreq_frequency_table_target(policy, freq_table,
+ target_freq, relation, &index);
+ freq_Hz = clk_round_rate(cpu_clk, cpu_freqs[index]);
+ freq_Hz = freq_Hz ? freq_Hz : cpu_freqs[index];
+ freqs.old = clk_get_rate(cpu_clk) / 1000;
+ freqs.new = freq_Hz / 1000;
+ freqs.flags = 0;
+
+ if (freqs.old == freqs.new)
+ return 0;
+
+ for_each_possible_cpu(cpu) {
+ freqs.cpu = cpu;
+ cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+ }
+
+ ret = set_cpu_freq(freq_Hz, index, (freqs.new > freqs.old));
+
+ for_each_possible_cpu(cpu) {
+ freqs.cpu = cpu;
+ cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+ }
+
+ return ret;
+}
+
+static int generic_cpufreq_init(struct cpufreq_policy *policy)
+{
+ int ret;
+
+ if (policy->cpu >= num_possible_cpus())
+ return -EINVAL;
+
+ policy->cur = clk_get_rate(cpu_clk) / 1000;
+ policy->shared_type = CPUFREQ_SHARED_TYPE_ANY;
+ cpumask_setall(policy->cpus);
+ /* Manual states, that PLL stabilizes in two CLK32 periods */
+ policy->cpuinfo.transition_latency = trans_latency;
+
+ ret = cpufreq_frequency_table_cpuinfo(policy, freq_table);
+
+ if (ret < 0) {
+ pr_err("%s: invalid frequency table for cpu %d\n",
+ __func__, policy->cpu);
+ return ret;
+ }
+
+ cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
+ return 0;
+}
+
+static int generic_cpufreq_exit(struct cpufreq_policy *policy)
+{
+ cpufreq_frequency_table_put_attr(policy->cpu);
+ return 0;
+}
+
+static struct cpufreq_driver generic_cpufreq_driver = {
+ .flags = CPUFREQ_STICKY,
+ .verify = generic_verify_speed,
+ .target = generic_set_target,
+ .get = generic_get_speed,
+ .init = generic_cpufreq_init,
+ .exit = generic_cpufreq_exit,
+ .name = "generic",
+};
+
+static int __devinit generic_cpufreq_driver_init(void)
+{
+ struct device_node *cpu0;
+ const struct property *pp;
+ int i, ret;
+
+ pr_info("Generic CPU frequency driver\n");
+
+ cpu0 = of_find_node_by_path("/cpus/cpu at 0");
+ if (!cpu0)
+ return -ENODEV;
+
+ if (!of_device_is_compatible(cpu0, "generic-cpufreq"))
+ return -ENODEV;
+
+ pp = of_find_property(cpu0, "cpu-freqs", NULL);
+ if (!pp) {
+ ret = -ENODEV;
+ goto put_node;
+ }
+ cpu_op_nr = pp->length / sizeof(u32);
+ if (!cpu_op_nr) {
+ ret = -ENODEV;
+ goto put_node;
+ }
+ ret = -ENOMEM;
+ cpu_freqs = kzalloc(sizeof(*cpu_freqs) * cpu_op_nr, GFP_KERNEL);
+ if (!cpu_freqs)
+ goto put_node;
+ of_property_read_u32_array(cpu0, "cpu-freqs", cpu_freqs, cpu_op_nr);
+
+ pp = of_find_property(cpu0, "cpu-volts", NULL);
+ if (pp) {
+ if (cpu_op_nr == pp->length / sizeof(u32)) {
+ cpu_volts = kzalloc(sizeof(*cpu_freqs) * cpu_op_nr,
+ GFP_KERNEL);
+ if (!cpu_volts)
+ goto free_cpu_freqs;
+ of_property_read_u32_array(cpu0, "cpu-volts",
+ cpu_volts, cpu_op_nr);
+ } else
+ pr_warn("%s: invalid cpu_volts!\n", __func__);
+ }
+
+ if (of_property_read_u32(cpu0, "trans-latency", &trans_latency))
+ trans_latency = CPUFREQ_ETERNAL;
+
+ freq_table = kmalloc(sizeof(struct cpufreq_frequency_table)
+ * (cpu_op_nr + 1), GFP_KERNEL);
+ if (!freq_table)
+ goto free_cpu_volts;
+
+ for (i = 0; i < cpu_op_nr; i++) {
+ freq_table[i].index = i;
+ freq_table[i].frequency = cpu_freqs[i] / 1000;
+ }
+
+ freq_table[i].index = i;
+ freq_table[i].frequency = CPUFREQ_TABLE_END;
+
+ cpu_clk = clk_get(NULL, "cpu");
+ if (IS_ERR(cpu_clk)) {
+ pr_err("%s: failed to get cpu clock\n", __func__);
+ ret = PTR_ERR(cpu_clk);
+ goto free_freq_table;
+ }
+
+ if (cpu_volts) {
+ cpu_reg = regulator_get(NULL, "cpu");
+ if (IS_ERR(cpu_reg)) {
+ pr_warn("%s: regulator cpu get failed.\n", __func__);
+ cpu_reg = NULL;
+ }
+ }
+
+ ret = cpufreq_register_driver(&generic_cpufreq_driver);
+ if (ret)
+ goto reg_put;
+
+ of_node_put(cpu0);
+
+ return 0;
+
+reg_put:
+ if (cpu_reg)
+ regulator_put(cpu_reg);
+ clk_put(cpu_clk);
+free_freq_table:
+ kfree(freq_table);
+free_cpu_volts:
+ kfree(cpu_volts);
+free_cpu_freqs:
+ kfree(cpu_freqs);
+put_node:
+ of_node_put(cpu0);
+
+ return ret;
+}
+
+static void generic_cpufreq_driver_exit(void)
+{
+ cpufreq_unregister_driver(&generic_cpufreq_driver);
+ kfree(cpu_freqs);
+ kfree(cpu_volts);
+ kfree(freq_table);
+ clk_put(cpu_clk);
+}
+
+module_init(generic_cpufreq_driver_init);
+module_exit(generic_cpufreq_driver_exit);
+
+MODULE_AUTHOR("Freescale Semiconductor Inc. Richard Zhao <richard.zhao at freescale.com>");
+MODULE_DESCRIPTION("Generic CPUFreq driver");
+MODULE_LICENSE("GPL");
--
1.7.5.4
More information about the linux-arm-kernel
mailing list