Re: [PATCH V3 4/7] cpufreq: add generic cpufreq driver

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@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@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@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