[PATCH V3 4/7] cpufreq: add generic cpufreq driver
Richard Zhao
richard.zhao at linaro.org
Tue Dec 20 01:20:09 EST 2011
On Mon, Dec 19, 2011 at 10:05:12AM +0000, Jamie Iles wrote:
> 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.
It'll prevent the driver from being a kernel module.
Hi Grant & Rob,
Could you comment?
>
> > +- 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.
right, Thanks. I can not check clk before generic clock framework
come in.
Added:
depends on OF && REGULATOR
select CPU_FREQ_TABLE
>
> > +
> > 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.
right, Thanks.
Added:
if (ret)
freq.new = clk_get_rate(cpu_clk) / 1000;
>
> > +
> > + 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"?
I ever thought about it. If it's exact, it'll be "generic-reg-clk-dt".
Is "generic-reg-clk" or "generic-reg-clk-dt" too long for file name?
>
> > +};
> > +
> > +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,
I still think checking compatible is better. So I need device tree
maintainer's comments.
> 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.
I should let it be tristate. If it's not compatible, I don't need
the module any more.
>
> > +
> > + 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?
right.
Added:
if (cpu_reg)
regulator_put(cpu_reg);
Thanks very much for your review!
Richard
>
> Jamie
More information about the devicetree-discuss
mailing list