It support single core and multi-core ARM SoCs. But it assume all cores share the same frequency and voltage.
Signed-off-by: Richard Zhao richard.zhao@linaro.org --- drivers/cpufreq/Kconfig.arm | 8 ++ drivers/cpufreq/Makefile | 1 + drivers/cpufreq/arm-cpufreq.c | 260 +++++++++++++++++++++++++++++++++++++++++ 3 files changed, 269 insertions(+), 0 deletions(-) create mode 100644 drivers/cpufreq/arm-cpufreq.c
diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm index 72a0044..a0f7d35 100644 --- a/drivers/cpufreq/Kconfig.arm +++ b/drivers/cpufreq/Kconfig.arm @@ -2,6 +2,14 @@ # ARM CPU Frequency scaling drivers #
+config ARM_GENERIC_CPUFREQ + bool "ARM generic" + help + This adds ARM generic CPUFreq driver. It assumes all + cores of the SoC share the same clock and voltage. + + If in doubt, say N. + config ARM_S3C64XX_CPUFREQ bool "Samsung S3C64XX" depends on CPU_S3C6410 diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile index ce75fcb..6ccf02d 100644 --- a/drivers/cpufreq/Makefile +++ b/drivers/cpufreq/Makefile @@ -39,6 +39,7 @@ obj-$(CONFIG_X86_CPUFREQ_NFORCE2) += cpufreq-nforce2.o
################################################################################## # ARM SoC drivers +obj-$(CONFIG_ARM_GENERIC_CPUFREQ) += arm-cpufreq.o obj-$(CONFIG_UX500_SOC_DB8500) += db8500-cpufreq.o obj-$(CONFIG_ARM_S3C64XX_CPUFREQ) += s3c64xx-cpufreq.o obj-$(CONFIG_ARM_S5PV210_CPUFREQ) += s5pv210-cpufreq.o diff --git a/drivers/cpufreq/arm-cpufreq.c b/drivers/cpufreq/arm-cpufreq.c new file mode 100644 index 0000000..fd9759f --- /dev/null +++ b/drivers/cpufreq/arm-cpufreq.c @@ -0,0 +1,260 @@ +/* + * Copyright (C) 2010 Freescale Semiconductor, Inc. All Rights Reserved. + */ + +/* + * 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/err.h> +#include <linux/slab.h> +#include <linux/of.h> +#include <asm/cpu.h> +#include <mach/hardware.h> +#include <mach/clock.h> + +static u32 *cpu_freqs; +static u32 *cpu_volts; +static u32 trans_latency; +static int cpu_op_nr; + +static int cpu_freq_khz_min; +static int cpu_freq_khz_max; + +static struct clk *cpu_clk; +static struct cpufreq_frequency_table *arm_freq_table; + +static int set_cpu_freq(int freq) +{ + int ret = 0; + int org_cpu_rate; + + org_cpu_rate = clk_get_rate(cpu_clk); + if (org_cpu_rate == freq) + return ret; + + ret = clk_set_rate(cpu_clk, freq); + if (ret != 0) { + printk(KERN_DEBUG "cannot set CPU clock rate\n"); + return ret; + } + + return ret; +} + +static int arm_verify_speed(struct cpufreq_policy *policy) +{ + return cpufreq_frequency_table_verify(policy, arm_freq_table); +} + +static unsigned int arm_get_speed(unsigned int cpu) +{ + return clk_get_rate(cpu_clk) / 1000; +} + +static int arm_set_target(struct cpufreq_policy *policy, + unsigned int target_freq, unsigned int relation) +{ + struct cpufreq_freqs freqs; + int freq_Hz, cpu; + int ret = 0; + unsigned int index; + + cpufreq_frequency_table_target(policy, arm_freq_table, + target_freq, relation, &index); + freq_Hz = arm_freq_table[index].frequency * 1000; + + freqs.old = clk_get_rate(cpu_clk) / 1000; + freqs.new = clk_round_rate(cpu_clk, freq_Hz); + freqs.new = (freqs.new ? 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); + +#ifdef CONFIG_SMP + /* loops_per_jiffy is not updated by the cpufreq core for SMP systems. + * So update it for all CPUs. + */ + for_each_possible_cpu(cpu) + per_cpu(cpu_data, cpu).loops_per_jiffy = + cpufreq_scale(per_cpu(cpu_data, cpu).loops_per_jiffy, + freqs.old, freqs.new); +#endif + + for_each_possible_cpu(cpu) { + freqs.cpu = cpu; + cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); + } + + return ret; +} + +static int arm_cpufreq_init(struct cpufreq_policy *policy) +{ + int ret; + + printk(KERN_INFO "ARM CPU frequency driver\n"); + + if (policy->cpu >= num_possible_cpus()) + return -EINVAL; + + policy->cur = clk_get_rate(cpu_clk) / 1000; + policy->min = policy->cpuinfo.min_freq = cpu_freq_khz_min; + policy->max = policy->cpuinfo.max_freq = cpu_freq_khz_max; + 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, arm_freq_table); + + if (ret < 0) { + printk(KERN_ERR "%s: failed to register i.MXC CPUfreq with error code %d\n", + __func__, ret); + return ret; + } + + cpufreq_frequency_table_get_attr(arm_freq_table, policy->cpu); + return 0; +} + +static int arm_cpufreq_exit(struct cpufreq_policy *policy) +{ + cpufreq_frequency_table_put_attr(policy->cpu); + + set_cpu_freq(cpu_freq_khz_max * 1000); + return 0; +} + +static struct cpufreq_driver arm_cpufreq_driver = { + .flags = CPUFREQ_STICKY, + .verify = arm_verify_speed, + .target = arm_set_target, + .get = arm_get_speed, + .init = arm_cpufreq_init, + .exit = arm_cpufreq_exit, + .name = "arm", +}; + +static int __devinit arm_cpufreq_driver_init(void) +{ + struct device_node *cpu0; + const struct property *pp; + int i, ret; + + cpu0 = of_find_node_by_path("/cpus/cpu@0"); + if (!cpu0) + 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_freqs, cpu_op_nr); + } else + printk(KERN_WARNING "cpufreq: invalid cpu_volts!\n"); + } + + if (of_property_read_u32(cpu0, "trans_latency", &trans_latency)) + trans_latency = CPUFREQ_ETERNAL; + + cpu_freq_khz_min = cpu_freqs[0] / 1000; + cpu_freq_khz_max = cpu_freqs[0] / 1000; + + arm_freq_table = kmalloc(sizeof(struct cpufreq_frequency_table) + * (cpu_op_nr + 1), GFP_KERNEL); + if (!arm_freq_table) + goto free_cpu_volts; + + for (i = 0; i < cpu_op_nr; i++) { + arm_freq_table[i].index = i; + arm_freq_table[i].frequency = cpu_freqs[i] / 1000; + if ((cpu_freqs[i] / 1000) < cpu_freq_khz_min) + cpu_freq_khz_min = cpu_freqs[i] / 1000; + if ((cpu_freqs[i] / 1000) > cpu_freq_khz_max) + cpu_freq_khz_max = cpu_freqs[i] / 1000; + } + + arm_freq_table[i].index = i; + arm_freq_table[i].frequency = CPUFREQ_TABLE_END; + + cpu_clk = clk_get(NULL, "cpu"); + if (IS_ERR(cpu_clk)) { + printk(KERN_ERR "%s: failed to get cpu clock\n", __func__); + ret = PTR_ERR(cpu_clk); + goto free_freq_table; + } + + ret = cpufreq_register_driver(&arm_cpufreq_driver); + if (ret) + goto clock_put; + + of_node_put(cpu0); + + return 0; + +clock_put: + clk_put(cpu_clk); +free_freq_table: + kfree(arm_freq_table); +free_cpu_volts: + kfree(cpu_volts); +free_cpu_freqs: + kfree(cpu_freqs); +put_node: + of_node_put(cpu0); + + return ret; +} + +static void arm_cpufreq_driver_exit(void) +{ + cpufreq_unregister_driver(&arm_cpufreq_driver); + kfree(cpu_freqs); + kfree(cpu_volts); + kfree(arm_freq_table); + clk_put(cpu_clk); +} + +module_init(arm_cpufreq_driver_init); +module_exit(arm_cpufreq_driver_exit); + +MODULE_AUTHOR("Freescale Semiconductor Inc. Richard Zhao richard.zhao@freescale.com"); +MODULE_DESCRIPTION("ARM SoC generic CPUFreq driver"); +MODULE_LICENSE("GPL");
Signed-off-by: Richard Zhao richard.zhao@linaro.org --- arch/arm/boot/dts/imx6q.dtsi | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/arch/arm/boot/dts/imx6q.dtsi b/arch/arm/boot/dts/imx6q.dtsi index 263e8f3..9e9943b 100644 --- a/arch/arm/boot/dts/imx6q.dtsi +++ b/arch/arm/boot/dts/imx6q.dtsi @@ -29,6 +29,8 @@ compatible = "arm,cortex-a9"; reg = <0>; next-level-cache = <&L2>; + cpu_freqs = <996000000 792000000 396000000 198000000>; + cpu_volts = <1225000 1100000 950000 850000>; };
cpu@1 {
Hi Richard,
Whenever we invent some new device tree binding support, we need to Cc devicetree-discuss@lists.ozlabs.org (Cc-ed).
On Thu, Dec 15, 2011 at 07:16:36PM +0800, Richard Zhao wrote:
Signed-off-by: Richard Zhao richard.zhao@linaro.org
arch/arm/boot/dts/imx6q.dtsi | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/arch/arm/boot/dts/imx6q.dtsi b/arch/arm/boot/dts/imx6q.dtsi index 263e8f3..9e9943b 100644 --- a/arch/arm/boot/dts/imx6q.dtsi +++ b/arch/arm/boot/dts/imx6q.dtsi @@ -29,6 +29,8 @@ compatible = "arm,cortex-a9"; reg = <0>; next-level-cache = <&L2>;
cpu_freqs = <996000000 792000000 396000000 198000000>;cpu_volts = <1225000 1100000 950000 850000>;
For dt property name, we use '-' rather than '_'.
And I'm not sure this is correct, since these data obviously does not belong to "arm,cortex-a9".
Regards, Shawn
};cpu@1 { -- 1.7.5.4
On Thu, Dec 15, 2011 at 07:58:54PM +0800, Shawn Guo wrote:
Hi Richard,
Whenever we invent some new device tree binding support, we need to Cc devicetree-discuss@lists.ozlabs.org (Cc-ed).
Thanks for your reminder.
On Thu, Dec 15, 2011 at 07:16:36PM +0800, Richard Zhao wrote:
Signed-off-by: Richard Zhao richard.zhao@linaro.org
arch/arm/boot/dts/imx6q.dtsi | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/arch/arm/boot/dts/imx6q.dtsi b/arch/arm/boot/dts/imx6q.dtsi index 263e8f3..9e9943b 100644 --- a/arch/arm/boot/dts/imx6q.dtsi +++ b/arch/arm/boot/dts/imx6q.dtsi @@ -29,6 +29,8 @@ compatible = "arm,cortex-a9"; reg = <0>; next-level-cache = <&L2>;
cpu_freqs = <996000000 792000000 396000000 198000000>;cpu_volts = <1225000 1100000 950000 850000>;For dt property name, we use '-' rather than '_'.
ok.
And I'm not sure this is correct, since these data obviously does not belong to "arm,cortex-a9".
That's why RFC.
Thanks Richard
Regards, Shawn
};cpu@1 { -- 1.7.5.4
linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
On 12/15/2011 05:16 AM, Richard Zhao wrote:
Signed-off-by: Richard Zhaorichard.zhao@linaro.org
arch/arm/boot/dts/imx6q.dtsi | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/arch/arm/boot/dts/imx6q.dtsi b/arch/arm/boot/dts/imx6q.dtsi index 263e8f3..9e9943b 100644 --- a/arch/arm/boot/dts/imx6q.dtsi +++ b/arch/arm/boot/dts/imx6q.dtsi @@ -29,6 +29,8 @@ compatible = "arm,cortex-a9"; reg =<0>; next-level-cache =<&L2>;
cpu_freqs =<996000000 792000000 396000000 198000000>;cpu_volts =<1225000 1100000 950000 850000>;
+ trans_latency =<3000>;
}; cpu@1 {
The trans_latency value definitely needs to be defined to avoid strange behavior in the driver.
--Mark Langsdorf Calxeda, Inc.
cpufreq needs cpu clock to change frequency.
Signed-off-by: Richard Zhao richard.zhao@linaro.org --- arch/arm/mach-imx/clock-imx6q.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/arch/arm/mach-imx/clock-imx6q.c b/arch/arm/mach-imx/clock-imx6q.c index 039a7ab..72acbc2 100644 --- a/arch/arm/mach-imx/clock-imx6q.c +++ b/arch/arm/mach-imx/clock-imx6q.c @@ -1911,6 +1911,7 @@ static struct clk_lookup lookups[] = { _REGISTER_CLOCK(NULL, "gpmi_io_clk", gpmi_io_clk), _REGISTER_CLOCK(NULL, "usboh3_clk", usboh3_clk), _REGISTER_CLOCK(NULL, "sata_clk", sata_clk), + _REGISTER_CLOCK(NULL, "cpu", arm_clk), };
int imx6q_set_lpm(enum mxc_cpu_pwr_mode mode)
Signed-off-by: Richard Zhao richard.zhao@linaro.org --- arch/arm/mach-imx/Kconfig | 1 + 1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/arch/arm/mach-imx/Kconfig b/arch/arm/mach-imx/Kconfig index c44aa97..39cf00a 100644 --- a/arch/arm/mach-imx/Kconfig +++ b/arch/arm/mach-imx/Kconfig @@ -595,6 +595,7 @@ comment "i.MX6 family:"
config SOC_IMX6Q bool "i.MX6 Quad support" + select ARCH_HAS_CPUFREQ select ARM_GIC select CACHE_L2X0 select CPU_V7
Comments below. I tested this on the Calxeda Highbank SoC using QEMU. I found one definite error and a few things I would change.
On 12/15/2011 05:16 AM, Richard Zhao wrote:
It support single core and multi-core ARM SoCs. But it assume all cores share the same frequency and voltage.
Signed-off-by: Richard Zhaorichard.zhao@linaro.org
diff --git a/drivers/cpufreq/arm-cpufreq.c b/drivers/cpufreq/arm-cpufreq.c new file mode 100644 index 0000000..fd9759f --- /dev/null +++ b/drivers/cpufreq/arm-cpufreq.c @@ -0,0 +1,260 @@ +/*
- Copyright (C) 2010 Freescale Semiconductor, Inc. All Rights Reserved.
- */
+/*
- 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:
- */
+#include<linux/module.h> +#include<linux/cpufreq.h> +#include<linux/clk.h> +#include<linux/err.h> +#include<linux/slab.h> +#include<linux/of.h> +#include<asm/cpu.h> +#include<mach/hardware.h> +#include<mach/clock.h>
These should probably be replaced by <linux/of_clk.h>. See below for details.
+static u32 *cpu_freqs; +static u32 *cpu_volts; +static u32 trans_latency; +static int cpu_op_nr;
+static int cpu_freq_khz_min; +static int cpu_freq_khz_max;
+static struct clk *cpu_clk; +static struct cpufreq_frequency_table *arm_freq_table;
+static int set_cpu_freq(int freq) +{
- int ret = 0;
- int org_cpu_rate;
- org_cpu_rate = clk_get_rate(cpu_clk);
- if (org_cpu_rate == freq)
return ret;- ret = clk_set_rate(cpu_clk, freq);
- if (ret != 0) {
printk(KERN_DEBUG "cannot set CPU clock rate\n");return ret;- }
- return ret;
+}
+static int arm_verify_speed(struct cpufreq_policy *policy) +{
- return cpufreq_frequency_table_verify(policy, arm_freq_table);
+}
+static unsigned int arm_get_speed(unsigned int cpu) +{
- return clk_get_rate(cpu_clk) / 1000;
+}
+static int arm_set_target(struct cpufreq_policy *policy,
unsigned int target_freq, unsigned int relation)+{
- struct cpufreq_freqs freqs;
- int freq_Hz, cpu;
- int ret = 0;
- unsigned int index;
- cpufreq_frequency_table_target(policy, arm_freq_table,
target_freq, relation,&index);- freq_Hz = arm_freq_table[index].frequency * 1000;
- freqs.old = clk_get_rate(cpu_clk) / 1000;
- freqs.new = clk_round_rate(cpu_clk, freq_Hz);
- freqs.new = (freqs.new ? 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);
+#ifdef CONFIG_SMP
- /* loops_per_jiffy is not updated by the cpufreq core for SMP systems.
* So update it for all CPUs.*/- for_each_possible_cpu(cpu)
per_cpu(cpu_data, cpu).loops_per_jiffy =cpufreq_scale(per_cpu(cpu_data, cpu).loops_per_jiffy,freqs.old, freqs.new);+#endif
- for_each_possible_cpu(cpu) {
freqs.cpu = cpu;cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);- }
- return ret;
+}
+static int arm_cpufreq_init(struct cpufreq_policy *policy) +{
- int ret;
- printk(KERN_INFO "ARM CPU frequency driver\n");
- if (policy->cpu>= num_possible_cpus())
return -EINVAL;- policy->cur = clk_get_rate(cpu_clk) / 1000;
- policy->min = policy->cpuinfo.min_freq = cpu_freq_khz_min;
- policy->max = policy->cpuinfo.max_freq = cpu_freq_khz_max;
- 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, arm_freq_table);
- if (ret< 0) {
printk(KERN_ERR "%s: failed to register i.MXC CPUfreq with error code %d\n",__func__, ret);return ret;- }
- cpufreq_frequency_table_get_attr(arm_freq_table, policy->cpu);
- return 0;
+}
+static int arm_cpufreq_exit(struct cpufreq_policy *policy) +{
- cpufreq_frequency_table_put_attr(policy->cpu);
- set_cpu_freq(cpu_freq_khz_max * 1000);
- return 0;
+}
+static struct cpufreq_driver arm_cpufreq_driver = {
- .flags = CPUFREQ_STICKY,
- .verify = arm_verify_speed,
- .target = arm_set_target,
- .get = arm_get_speed,
- .init = arm_cpufreq_init,
- .exit = arm_cpufreq_exit,
- .name = "arm",
+};
+static int __devinit arm_cpufreq_driver_init(void) +{
- struct device_node *cpu0;
- const struct property *pp;
- int i, ret;
- cpu0 = of_find_node_by_path("/cpus/cpu@0");
- if (!cpu0)
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_freqs, cpu_op_nr);
cpu_freqs should clearly be cpu_volts in this instance.
} elseprintk(KERN_WARNING "cpufreq: invalid cpu_volts!\n");- }
- if (of_property_read_u32(cpu0, "trans_latency",&trans_latency))
trans_latency = CPUFREQ_ETERNAL;
I'm not sure this is an appropriate default value. I suspect it will do very strange things on actual hardware that fails to define trans_latency in the device tree.
- cpu_freq_khz_min = cpu_freqs[0] / 1000;
- cpu_freq_khz_max = cpu_freqs[0] / 1000;
- arm_freq_table = kmalloc(sizeof(struct cpufreq_frequency_table)
* (cpu_op_nr + 1), GFP_KERNEL);- if (!arm_freq_table)
goto free_cpu_volts;- for (i = 0; i< cpu_op_nr; i++) {
arm_freq_table[i].index = i;arm_freq_table[i].frequency = cpu_freqs[i] / 1000;if ((cpu_freqs[i] / 1000)< cpu_freq_khz_min)cpu_freq_khz_min = cpu_freqs[i] / 1000;if ((cpu_freqs[i] / 1000)> cpu_freq_khz_max)cpu_freq_khz_max = cpu_freqs[i] / 1000;- }
- arm_freq_table[i].index = i;
- arm_freq_table[i].frequency = CPUFREQ_TABLE_END;
- cpu_clk = clk_get(NULL, "cpu");
- if (IS_ERR(cpu_clk)) {
printk(KERN_ERR "%s: failed to get cpu clock\n", __func__);ret = PTR_ERR(cpu_clk);goto free_freq_table;- }
I'd prefer to see clk_get90 replaced with of_clk_get() and get_this_cpu_node() from the clk-cpufreq driver by Jamie Iles that I resubmitted yesterday. The of_clk_get() doesn't require defining an arm_clk structure, so it's slightly more portable for mach- definitions. Also, the of_clk_get() method doesn't require mach/clock.h and mach/hardware.h, which is good because most of the mach- definitions don't include them.
--Mark Langsdorf Calxeda, Inc.
On Thu, Dec 15, 2011 at 12:50:07PM -0600, Mark Langsdorf wrote:
Comments below. I tested this on the Calxeda Highbank SoC using QEMU. I found one definite error and a few things I would change.
Thanks for your test.
On 12/15/2011 05:16 AM, Richard Zhao wrote:
It support single core and multi-core ARM SoCs. But it assume all cores share the same frequency and voltage.
Signed-off-by: Richard Zhaorichard.zhao@linaro.org
diff --git a/drivers/cpufreq/arm-cpufreq.c b/drivers/cpufreq/arm-cpufreq.c new file mode 100644 index 0000000..fd9759f --- /dev/null +++ b/drivers/cpufreq/arm-cpufreq.c @@ -0,0 +1,260 @@ +/*
- Copyright (C) 2010 Freescale Semiconductor, Inc. All Rights Reserved.
- */
+/*
- 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:
- */
+#include<linux/module.h> +#include<linux/cpufreq.h> +#include<linux/clk.h> +#include<linux/err.h> +#include<linux/slab.h> +#include<linux/of.h> +#include<asm/cpu.h> +#include<mach/hardware.h> +#include<mach/clock.h>
These should probably be replaced by <linux/of_clk.h>. See below for details.
I'll remove <mach/*>. But are you sure clk DT binding has went to -next or -rc? If yes, I'm glad to use it. If no, I don't want to pend on it.
+static u32 *cpu_freqs; +static u32 *cpu_volts; +static u32 trans_latency; +static int cpu_op_nr;
+static int cpu_freq_khz_min; +static int cpu_freq_khz_max;
+static struct clk *cpu_clk; +static struct cpufreq_frequency_table *arm_freq_table;
+static int set_cpu_freq(int freq) +{
- int ret = 0;
- int org_cpu_rate;
- org_cpu_rate = clk_get_rate(cpu_clk);
- if (org_cpu_rate == freq)
return ret;- ret = clk_set_rate(cpu_clk, freq);
- if (ret != 0) {
printk(KERN_DEBUG "cannot set CPU clock rate\n");return ret;- }
- return ret;
+}
+static int arm_verify_speed(struct cpufreq_policy *policy) +{
- return cpufreq_frequency_table_verify(policy, arm_freq_table);
+}
+static unsigned int arm_get_speed(unsigned int cpu) +{
- return clk_get_rate(cpu_clk) / 1000;
+}
+static int arm_set_target(struct cpufreq_policy *policy,
unsigned int target_freq, unsigned int relation)+{
- struct cpufreq_freqs freqs;
- int freq_Hz, cpu;
- int ret = 0;
- unsigned int index;
- cpufreq_frequency_table_target(policy, arm_freq_table,
target_freq, relation,&index);- freq_Hz = arm_freq_table[index].frequency * 1000;
- freqs.old = clk_get_rate(cpu_clk) / 1000;
- freqs.new = clk_round_rate(cpu_clk, freq_Hz);
- freqs.new = (freqs.new ? 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);
+#ifdef CONFIG_SMP
- /* loops_per_jiffy is not updated by the cpufreq core for SMP systems.
* So update it for all CPUs.*/- for_each_possible_cpu(cpu)
per_cpu(cpu_data, cpu).loops_per_jiffy =cpufreq_scale(per_cpu(cpu_data, cpu).loops_per_jiffy,freqs.old, freqs.new);+#endif
- for_each_possible_cpu(cpu) {
freqs.cpu = cpu;cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);- }
- return ret;
+}
+static int arm_cpufreq_init(struct cpufreq_policy *policy) +{
- int ret;
- printk(KERN_INFO "ARM CPU frequency driver\n");
- if (policy->cpu>= num_possible_cpus())
return -EINVAL;- policy->cur = clk_get_rate(cpu_clk) / 1000;
- policy->min = policy->cpuinfo.min_freq = cpu_freq_khz_min;
- policy->max = policy->cpuinfo.max_freq = cpu_freq_khz_max;
- 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, arm_freq_table);
- if (ret< 0) {
printk(KERN_ERR "%s: failed to register i.MXC CPUfreq with error code %d\n",__func__, ret);return ret;- }
- cpufreq_frequency_table_get_attr(arm_freq_table, policy->cpu);
- return 0;
+}
+static int arm_cpufreq_exit(struct cpufreq_policy *policy) +{
- cpufreq_frequency_table_put_attr(policy->cpu);
- set_cpu_freq(cpu_freq_khz_max * 1000);
- return 0;
+}
+static struct cpufreq_driver arm_cpufreq_driver = {
- .flags = CPUFREQ_STICKY,
- .verify = arm_verify_speed,
- .target = arm_set_target,
- .get = arm_get_speed,
- .init = arm_cpufreq_init,
- .exit = arm_cpufreq_exit,
- .name = "arm",
+};
+static int __devinit arm_cpufreq_driver_init(void) +{
- struct device_node *cpu0;
- const struct property *pp;
- int i, ret;
- cpu0 = of_find_node_by_path("/cpus/cpu@0");
- if (!cpu0)
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_freqs, cpu_op_nr);cpu_freqs should clearly be cpu_volts in this instance.
Thanks.
} elseprintk(KERN_WARNING "cpufreq: invalid cpu_volts!\n");- }
- if (of_property_read_u32(cpu0, "trans_latency",&trans_latency))
trans_latency = CPUFREQ_ETERNAL;I'm not sure this is an appropriate default value. I suspect it will do very strange things on actual hardware that fails to define trans_latency in the device tree.
CPUFREQ_ETERNAL breaks governor ondemand and conservative. But it's the recommended default vaule in cpufreq doc.
- cpu_freq_khz_min = cpu_freqs[0] / 1000;
- cpu_freq_khz_max = cpu_freqs[0] / 1000;
- arm_freq_table = kmalloc(sizeof(struct cpufreq_frequency_table)
* (cpu_op_nr + 1), GFP_KERNEL);- if (!arm_freq_table)
goto free_cpu_volts;- for (i = 0; i< cpu_op_nr; i++) {
arm_freq_table[i].index = i;arm_freq_table[i].frequency = cpu_freqs[i] / 1000;if ((cpu_freqs[i] / 1000)< cpu_freq_khz_min)cpu_freq_khz_min = cpu_freqs[i] / 1000;if ((cpu_freqs[i] / 1000)> cpu_freq_khz_max)cpu_freq_khz_max = cpu_freqs[i] / 1000;- }
- arm_freq_table[i].index = i;
- arm_freq_table[i].frequency = CPUFREQ_TABLE_END;
- cpu_clk = clk_get(NULL, "cpu");
- if (IS_ERR(cpu_clk)) {
printk(KERN_ERR "%s: failed to get cpu clock\n", __func__);ret = PTR_ERR(cpu_clk);goto free_freq_table;- }
I'd prefer to see clk_get90 replaced with of_clk_get()
ditto
and get_this_cpu_node() from the clk-cpufreq driver by Jamie Iles that I resubmitted yesterday.
This driver only have one instance, because all cpu cores shares the same clk and voltage. You can see cpumask_setall(policy->cpus). And get_this_cpu_node() adds the dependency that cpufreq_driver.init must run on the cpu the policy indicate, which is not correct.
Thanks for your comments Richard
The of_clk_get() doesn't require defining an arm_clk structure, so it's slightly more portable for mach- definitions. Also, the of_clk_get() method doesn't require mach/clock.h and mach/hardware.h, which is good because most of the mach- definitions don't include them.
--Mark Langsdorf Calxeda, Inc.
linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
On Fri, Dec 16, 2011 at 08:24:23AM +0000, Russell King - ARM Linux wrote:
On Thu, Dec 15, 2011 at 12:50:07PM -0600, Mark Langsdorf wrote:
I'd prefer to see clk_get90 replaced with of_clk_get() and get_this_cpu_node() from the clk-cpufreq driver by Jamie Iles that I resubmitted yesterday.
Why isn't of_clk_get() hidden inside clk_get() ?
Good point.
linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
On Thu, Dec 15, 2011 at 07:16:35PM +0800, Richard Zhao wrote:
+#ifdef CONFIG_SMP
- /* loops_per_jiffy is not updated by the cpufreq core for SMP systems.
* So update it for all CPUs.*/- for_each_possible_cpu(cpu)
per_cpu(cpu_data, cpu).loops_per_jiffy =cpufreq_scale(per_cpu(cpu_data, cpu).loops_per_jiffy,freqs.old, freqs.new);
NAK. If you think this is a good solution, you're very wrong. If this is what's in the core cpufreq code, then it too is very broken.
I've seen this exact method result in the loops_per_jiffy being totally buggered over time by the constant scaling up and down. The only way to do this _sensibly_ is to record the _initial_ loops_per_jiffy and _inital_ frequency, and scale from that.
That way you get consistent results irrespective of the scalings you do over time, rather than something which continually deteriorates with every frequency change.
On Thu, Dec 15, 2011 at 08:29:11PM +0000, Russell King - ARM Linux wrote:
On Thu, Dec 15, 2011 at 07:16:35PM +0800, Richard Zhao wrote:
+#ifdef CONFIG_SMP
- /* loops_per_jiffy is not updated by the cpufreq core for SMP systems.
* So update it for all CPUs.*/- for_each_possible_cpu(cpu)
per_cpu(cpu_data, cpu).loops_per_jiffy =cpufreq_scale(per_cpu(cpu_data, cpu).loops_per_jiffy,freqs.old, freqs.new);NAK. If you think this is a good solution, you're very wrong. If this is what's in the core cpufreq code, then it too is very broken.
I've seen this exact method result in the loops_per_jiffy being totally buggered over time by the constant scaling up and down. The only way to do this _sensibly_ is to record the _initial_ loops_per_jiffy and _inital_ frequency, and scale from that.
That way you get consistent results irrespective of the scalings you do over time, rather than something which continually deteriorates with every frequency change.
Thanks for your comments. I'll recalculate loops_per_jiffy always based on boot up values.
Thanks Richard
linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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Mark Langsdorf -
Richard Zhao -
Richard Zhao -
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