[PATCH V3 4/7] cpufreq: add generic cpufreq driver
Jamie Iles
jamie at jamieiles.com
Mon Dec 19 21:05:12 EST 2011
Hi Richard,
On Mon, Dec 19, 2011 at 11:21:40AM +0800, Richard Zhao wrote:
> 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"
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.
> +- 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.
I think this needs dependencies on HAVE_CLK, OF and REGULATOR.
> +
> 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));
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 at 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
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