* [PATCH 9/9] [ARM] tegra: Add cpufreq support
[not found] <1280449771-24043-1-git-send-email-ccross@google.com>
@ 2010-07-30 0:29 ` Colin Cross
2010-07-30 13:11 ` Dominik Brodowski
0 siblings, 1 reply; 6+ messages in thread
From: Colin Cross @ 2010-07-30 0:29 UTC (permalink / raw)
To: linux-tegra; +Cc: linux-arm-kernel, Colin Cross, cpufreq
From: Colin Cross <ccross@android.com>
Implement cpufreq support for the Tegra SOC. DVFS is handled by the
core virtual cpu clock. The frequencies of the two cores are tied
together, the highest frequency requested by either core determines
the actual frequency.
CC: cpufreq@vger.kernel.org
Signed-off-by: Colin Cross <ccross@android.com>
---
arch/arm/Kconfig | 1 +
arch/arm/mach-tegra/Makefile | 1 +
arch/arm/mach-tegra/cpu-tegra.c | 185 +++++++++++++++++++++++++++++++++++++++
3 files changed, 187 insertions(+), 0 deletions(-)
create mode 100644 arch/arm/mach-tegra/cpu-tegra.c
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 1341628..1ccf0d3 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -569,6 +569,7 @@ config ARCH_TEGRA
select HAVE_CLK
select COMMON_CLKDEV
select ARCH_HAS_BARRIERS if CACHE_L2X0
+ select ARCH_HAS_CPUFREQ
help
This enables support for NVIDIA Tegra based systems (Tegra APX,
Tegra 6xx and Tegra 2 series).
diff --git a/arch/arm/mach-tegra/Makefile b/arch/arm/mach-tegra/Makefile
index 3642e58..2a37621 100644
--- a/arch/arm/mach-tegra/Makefile
+++ b/arch/arm/mach-tegra/Makefile
@@ -12,6 +12,7 @@ obj-$(CONFIG_ARCH_TEGRA_2x_SOC) += tegra2_dvfs.o
obj-$(CONFIG_ARCH_TEGRA_2x_SOC) += pinmux-t2-tables.o
obj-$(CONFIG_SMP) += platsmp.o localtimer.o headsmp.o
obj-$(CONFIG_HOTPLUG_CPU) += hotplug.o
+obj-$(CONFIG_CPU_FREQ) += cpu-tegra.o
obj-${CONFIG_MACH_HARMONY} += board-harmony.o
obj-${CONFIG_MACH_HARMONY} += board-harmony-pinmux.o
diff --git a/arch/arm/mach-tegra/cpu-tegra.c b/arch/arm/mach-tegra/cpu-tegra.c
new file mode 100644
index 0000000..fea5719
--- /dev/null
+++ b/arch/arm/mach-tegra/cpu-tegra.c
@@ -0,0 +1,185 @@
+/*
+ * arch/arm/mach-tegra/cpu-tegra.c
+ *
+ * Copyright (C) 2010 Google, Inc.
+ *
+ * Author:
+ * Colin Cross <ccross@google.com>
+ * Based on arch/arm/plat-omap/cpu-omap.c, (C) 2005 Nokia Corporation
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <linux/cpufreq.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+
+#include <asm/system.h>
+
+#include <mach/hardware.h>
+#include <mach/clk.h>
+
+/* Frequency table index must be sequential starting at 0 */
+static struct cpufreq_frequency_table freq_table[] = {
+ { 0, 312000 },
+ { 1, 456000 },
+ { 2, 608000 },
+ { 3, 760000 },
+ { 4, 816000 },
+ { 5, 912000 },
+ { 6, 1000000 },
+ { 7, CPUFREQ_TABLE_END },
+};
+
+#define NUM_CPUS 2
+
+static struct clk *cpu_clk;
+
+static unsigned long target_cpu_speed[NUM_CPUS];
+
+int tegra_verify_speed(struct cpufreq_policy *policy)
+{
+ return cpufreq_frequency_table_verify(policy, freq_table);
+}
+
+unsigned int tegra_getspeed(unsigned int cpu)
+{
+ unsigned long rate;
+
+ if (cpu >= NUM_CPUS)
+ return 0;
+
+ rate = clk_get_rate(cpu_clk) / 1000;
+ return rate;
+}
+
+static int tegra_update_cpu_speed(void)
+{
+ int i;
+ unsigned long rate = 0;
+ int ret = 0;
+ struct cpufreq_freqs freqs;
+
+ for_each_online_cpu(i)
+ rate = max(rate, target_cpu_speed[i]);
+
+ freqs.old = tegra_getspeed(0);
+ freqs.new = rate;
+
+ if (freqs.old == freqs.new)
+ return ret;
+
+ for_each_online_cpu(freqs.cpu)
+ cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+
+#ifdef CONFIG_CPU_FREQ_DEBUG
+ printk(KERN_DEBUG "cpufreq-tegra: transition: %u --> %u\n",
+ freqs.old, freqs.new);
+#endif
+
+ ret = clk_set_rate_cansleep(cpu_clk, freqs.new * 1000);
+ if (ret) {
+ pr_err("cpu-tegra: Failed to set cpu frequency to %d kHz\n",
+ freqs.new);
+ return ret;
+ }
+
+ for_each_online_cpu(freqs.cpu)
+ cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+
+ return 0;
+}
+
+static int tegra_target(struct cpufreq_policy *policy,
+ unsigned int target_freq,
+ unsigned int relation)
+{
+ int idx;
+ unsigned int freq;
+
+ cpufreq_frequency_table_target(policy, freq_table, target_freq,
+ relation, &idx);
+
+ freq = freq_table[idx].frequency;
+
+ target_cpu_speed[policy->cpu] = freq;
+
+ return tegra_update_cpu_speed();
+}
+
+static int tegra_cpu_init(struct cpufreq_policy *policy)
+{
+ if (policy->cpu >= NUM_CPUS)
+ return -EINVAL;
+
+ cpu_clk = clk_get_sys(NULL, "cpu");
+ if (IS_ERR(cpu_clk))
+ return PTR_ERR(cpu_clk);
+
+ cpufreq_frequency_table_cpuinfo(policy, freq_table);
+ cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
+ policy->cur = tegra_getspeed(policy->cpu);
+ target_cpu_speed[policy->cpu] = policy->cur;
+
+ /* FIXME: what's the actual transition time? */
+ policy->cpuinfo.transition_latency = 300 * 1000;
+
+ policy->shared_type = CPUFREQ_SHARED_TYPE_ALL;
+ cpumask_copy(policy->related_cpus, cpu_possible_mask);
+
+ return 0;
+}
+
+static int tegra_cpu_exit(struct cpufreq_policy *policy)
+{
+ cpufreq_frequency_table_cpuinfo(policy, freq_table);
+ clk_put(cpu_clk);
+ return 0;
+}
+
+static struct freq_attr *tegra_cpufreq_attr[] = {
+ &cpufreq_freq_attr_scaling_available_freqs,
+ NULL,
+};
+
+static struct cpufreq_driver tegra_cpufreq_driver = {
+ .verify = tegra_verify_speed,
+ .target = tegra_target,
+ .get = tegra_getspeed,
+ .init = tegra_cpu_init,
+ .exit = tegra_cpu_exit,
+ .name = "tegra",
+ .attr = tegra_cpufreq_attr,
+};
+
+static int __init tegra_cpufreq_init(void)
+{
+ return cpufreq_register_driver(&tegra_cpufreq_driver);
+}
+
+static void __exit tegra_cpufreq_exit(void)
+{
+ cpufreq_unregister_driver(&tegra_cpufreq_driver);
+}
+
+
+MODULE_AUTHOR("Colin Cross <ccross@android.com>");
+MODULE_DESCRIPTION("cpufreq driver for Nvidia Tegra2");
+MODULE_LICENSE("GPL");
+module_init(tegra_cpufreq_init);
+module_exit(tegra_cpufreq_exit);
--
1.7.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH 9/9] [ARM] tegra: Add cpufreq support
2010-07-30 0:29 ` [PATCH 9/9] [ARM] tegra: Add cpufreq support Colin Cross
@ 2010-07-30 13:11 ` Dominik Brodowski
2010-07-30 19:56 ` Colin Cross
0 siblings, 1 reply; 6+ messages in thread
From: Dominik Brodowski @ 2010-07-30 13:11 UTC (permalink / raw)
To: Colin Cross; +Cc: linux-tegra, linux-arm-kernel, Colin Cross, cpufreq
Hey,
just a few minor comments:
On Thu, Jul 29, 2010 at 05:29:30PM -0700, Colin Cross wrote:
> +int tegra_verify_speed(struct cpufreq_policy *policy)
static int
> +unsigned int tegra_getspeed(unsigned int cpu)
static unsined int
> + for_each_online_cpu(freqs.cpu)
> + cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
> +
> +#ifdef CONFIG_CPU_FREQ_DEBUG
> + printk(KERN_DEBUG "cpufreq-tegra: transition: %u --> %u\n",
> + freqs.old, freqs.new);
> +#endif
What about using cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, ... ) here?
> +
> + ret = clk_set_rate_cansleep(cpu_clk, freqs.new * 1000);
"can sleep"? For how long?
Best,
Dominik
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 9/9] [ARM] tegra: Add cpufreq support
2010-07-30 13:11 ` Dominik Brodowski
@ 2010-07-30 19:56 ` Colin Cross
2010-07-30 20:20 ` Mark Brown
0 siblings, 1 reply; 6+ messages in thread
From: Colin Cross @ 2010-07-30 19:56 UTC (permalink / raw)
To: Dominik Brodowski; +Cc: linux-tegra, linux-arm-kernel, cpufreq
On Fri, Jul 30, 2010 at 6:11 AM, Dominik Brodowski
<linux@dominikbrodowski.net> wrote:
> Hey,
>
> just a few minor comments:
>
> On Thu, Jul 29, 2010 at 05:29:30PM -0700, Colin Cross wrote:
>> +int tegra_verify_speed(struct cpufreq_policy *policy)
> static int
Done
>> +unsigned int tegra_getspeed(unsigned int cpu)
> static unsined int
Done
>> + for_each_online_cpu(freqs.cpu)
>> + cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
>> +
>> +#ifdef CONFIG_CPU_FREQ_DEBUG
>> + printk(KERN_DEBUG "cpufreq-tegra: transition: %u --> %u\n",
>> + freqs.old, freqs.new);
>> +#endif
> What about using cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, ... ) here?
>
>> +
>> + ret = clk_set_rate_cansleep(cpu_clk, freqs.new * 1000);
> "can sleep"? For how long?
Adjusting the CPU clock may require changing the voltage through the
regulator api, which locks a mutex, and eventually through I2C, which
sleeps on I2C completion.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 9/9] [ARM] tegra: Add cpufreq support
2010-07-30 19:56 ` Colin Cross
@ 2010-07-30 20:20 ` Mark Brown
2010-07-30 20:33 ` Colin Cross
0 siblings, 1 reply; 6+ messages in thread
From: Mark Brown @ 2010-07-30 20:20 UTC (permalink / raw)
To: Colin Cross; +Cc: Dominik Brodowski, linux-tegra, linux-arm-kernel, cpufreq
On Fri, Jul 30, 2010 at 12:56:33PM -0700, Colin Cross wrote:
> On Fri, Jul 30, 2010 at 6:11 AM, Dominik Brodowski
> >> + ? ? ret = clk_set_rate_cansleep(cpu_clk, freqs.new * 1000);
> > "can sleep"? For how long?
> Adjusting the CPU clock may require changing the voltage through the
> regulator api, which locks a mutex, and eventually through I2C, which
> sleeps on I2C completion.
...although in some systems the I2C cost will be replaced with updating
a GPIO which is very much cheaper.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 9/9] [ARM] tegra: Add cpufreq support
2010-07-30 20:20 ` Mark Brown
@ 2010-07-30 20:33 ` Colin Cross
2010-07-30 21:14 ` Mark Brown
0 siblings, 1 reply; 6+ messages in thread
From: Colin Cross @ 2010-07-30 20:33 UTC (permalink / raw)
To: Mark Brown; +Cc: Dominik Brodowski, linux-tegra, linux-arm-kernel, cpufreq
On Fri, Jul 30, 2010 at 1:20 PM, Mark Brown
<broonie@opensource.wolfsonmicro.com> wrote:
> On Fri, Jul 30, 2010 at 12:56:33PM -0700, Colin Cross wrote:
>> On Fri, Jul 30, 2010 at 6:11 AM, Dominik Brodowski
>
>> >> + ? ? ret = clk_set_rate_cansleep(cpu_clk, freqs.new * 1000);
>> > "can sleep"? For how long?
>
>> Adjusting the CPU clock may require changing the voltage through the
>> regulator api, which locks a mutex, and eventually through I2C, which
>> sleeps on I2C completion.
>
> ...although in some systems the I2C cost will be replaced with updating
> a GPIO which is very much cheaper.
Yes, but even on a GPIO regulator, the regulator api will lock a mutex
and possibly schedule.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 9/9] [ARM] tegra: Add cpufreq support
2010-07-30 20:33 ` Colin Cross
@ 2010-07-30 21:14 ` Mark Brown
0 siblings, 0 replies; 6+ messages in thread
From: Mark Brown @ 2010-07-30 21:14 UTC (permalink / raw)
To: Colin Cross; +Cc: linux-tegra, cpufreq, linux-arm-kernel, Dominik Brodowski
On Fri, Jul 30, 2010 at 01:33:08PM -0700, Colin Cross wrote:
> On Fri, Jul 30, 2010 at 1:20 PM, Mark Brown
> > ...although in some systems the I2C cost will be replaced with updating
> > a GPIO which is very much cheaper.
> Yes, but even on a GPIO regulator, the regulator api will lock a mutex
> and possibly schedule.
Yup, the schedule will depend on how long it takes to charge the cap on
the output in the case of the GPIO regulator. The point being that the
delay you'll encounter is wildly variable depending on hardware setup.
^ permalink raw reply [flat|nested] 6+ messages in thread
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2010-07-30 0:29 ` [PATCH 9/9] [ARM] tegra: Add cpufreq support Colin Cross
2010-07-30 13:11 ` Dominik Brodowski
2010-07-30 19:56 ` Colin Cross
2010-07-30 20:20 ` Mark Brown
2010-07-30 20:33 ` Colin Cross
2010-07-30 21:14 ` Mark Brown
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