Re: [PATCH V3 4/7] cpufreq: add generic cpufreq driver
From: Jamie Iles <hidden>
Date: 2011-12-19 10:05:12
Also in:
linux-arm-kernel
Hi Richard, On Mon, Dec 19, 2011 at 11:21:40AM +0800, Richard Zhao wrote:
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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 <redacted> --- .../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.cdiff --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@0: +- compatible : "generic-cpufreq"
I'm not convinced this is the best way to do this. By requiring a generic-cpufreq compatible string we're encoding Linux driver information into the hardware description. The only way I can see to avoid this is to provide a generic_clk_cpufreq_init() function that platforms can call in their machine init code to use the driver.
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+- cpu-freqs : cpu frequency points it support +- cpu-volts : cpu voltages required by the frequency point at the same index +- trans-latency : transition_latencydiff --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.
I think this needs dependencies on HAVE_CLK, OF and REGULATOR.
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+ 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 earlydiff --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));
If this fails then we'll still be notifying the transition at the requested rate even though it didn't work. I guess we should really get the rate of the clk and put that into freqs for the POSTCHANGE notification.
+
+ 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",This may be a little too generic? "generic-reg-clk"?
+};
+
+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@0");
+ if (!cpu0)
+ return -ENODEV;
+
+ if (!of_device_is_compatible(cpu0, "generic-cpufreq"))
+ return -ENODEV;As above, I'd personally rather not use compatible strings, but if you do, then I think return 0 here rather than -ENODEV else I believe you'll get a potentially confusing message on the console for platforms that don't use this.
+
+ 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);Should this do something with the regulator too? Jamie