diff options
author | Viresh Kumar <viresh.kumar@linaro.org> | 2013-04-01 12:57:49 (GMT) |
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committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2013-04-02 13:26:32 (GMT) |
commit | 8a67f0ef2b684b34162d39e8f436fe39e9635a19 (patch) | |
tree | dc997ac3064c69e775485213b824e7c3efeb5b99 /drivers/cpufreq/arm_big_little_dt.c | |
parent | eb2f50ff93f08c8001d0d7e1148948ba80989aaf (diff) | |
download | linux-fsl-qoriq-8a67f0ef2b684b34162d39e8f436fe39e9635a19.tar.xz |
cpufreq: ARM big LITTLE: Add generic cpufreq driver and its DT glue
big LITTLE is ARM's new Architecture focussing power/performance needs of modern
world. More information about big LITTLE can be found here:
http://www.arm.com/products/processors/technologies/biglittleprocessing.php
http://lwn.net/Articles/481055/
In order to keep cpufreq support for all big LITTLE platforms simple/generic,
this patch tries to add a generic cpufreq driver layer for all big LITTLE
platforms.
The driver is divided into two parts:
- Core driver: Generic and shared across all big LITTLE SoC's
- Glue drivers: Per platform drivers providing ops to the core driver
This patch adds in a generic glue driver which would extract information from
Device Tree.
Future SoC's can either reuse the DT glue or write their own depending on the
need.
Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq/arm_big_little_dt.c')
-rw-r--r-- | drivers/cpufreq/arm_big_little_dt.c | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/drivers/cpufreq/arm_big_little_dt.c b/drivers/cpufreq/arm_big_little_dt.c new file mode 100644 index 0000000..452ff46 --- /dev/null +++ b/drivers/cpufreq/arm_big_little_dt.c @@ -0,0 +1,92 @@ +/* + * Generic big.LITTLE CPUFreq Interface driver + * + * It provides necessary ops to arm_big_little cpufreq driver and gets + * Frequency information from Device Tree. Freq table in DT must be in KHz. + * + * Copyright (C) 2013 Linaro. + * Viresh Kumar <viresh.kumar@linaro.org> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed "as is" WITHOUT ANY WARRANTY of any + * kind, whether express or implied; without even the implied warranty + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/cpufreq.h> +#include <linux/device.h> +#include <linux/export.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/opp.h> +#include <linux/slab.h> +#include <linux/types.h> +#include "arm_big_little.h" + +static int dt_init_opp_table(struct device *cpu_dev) +{ + struct device_node *np = NULL; + int count = 0, ret; + + for_each_child_of_node(of_find_node_by_path("/cpus"), np) { + if (count++ != cpu_dev->id) + continue; + if (!of_get_property(np, "operating-points", NULL)) + return -ENODATA; + + cpu_dev->of_node = np; + + ret = of_init_opp_table(cpu_dev); + if (ret) + return ret; + + return 0; + } + + return -ENODEV; +} + +static int dt_get_transition_latency(struct device *cpu_dev) +{ + struct device_node *np = NULL; + u32 transition_latency = CPUFREQ_ETERNAL; + int count = 0; + + for_each_child_of_node(of_find_node_by_path("/cpus"), np) { + if (count++ != cpu_dev->id) + continue; + + of_property_read_u32(np, "clock-latency", &transition_latency); + return 0; + } + + return -ENODEV; +} + +static struct cpufreq_arm_bL_ops dt_bL_ops = { + .name = "dt-bl", + .get_transition_latency = dt_get_transition_latency, + .init_opp_table = dt_init_opp_table, +}; + +static int generic_bL_init(void) +{ + return bL_cpufreq_register(&dt_bL_ops); +} +module_init(generic_bL_init); + +static void generic_bL_exit(void) +{ + return bL_cpufreq_unregister(&dt_bL_ops); +} +module_exit(generic_bL_exit); + +MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>"); +MODULE_DESCRIPTION("Generic ARM big LITTLE cpufreq driver via DT"); +MODULE_LICENSE("GPL"); |