| Message ID | 1405958786-17243-3-git-send-email-lorenzo.pieralisi@arm.com (mailing list archive) |
|---|---|
| State | Deferred, archived |
| Headers | show |
On 07/21/2014 06:06 PM, Lorenzo Pieralisi wrote: > On most common ARM systems, the low-power states a CPU can be put into are > not discoverable in HW and require device tree bindings to describe > power down suspend operations and idle states parameters. > > In order to enable DT based idle states and configure idle drivers, this > patch implements the bulk infrastructure required to parse the device tree > idle states bindings and initialize the corresponding CPUidle driver states > data. > > The parsing API accepts a start index that defines the first idle state > that should be initialized by the parsing code in order to give new and > legacy driver flexibility over which states should be parsed using the > new DT mechanism. > > The idle states list is obtained from the first cpu in the driver > cpumask, which implicitly means the parsing code expects idle states > (and related list of phandles) to be the same for all CPUs in the > CPUidle driver mask. The kernel does not check this assumption, it must > be enforced by the bootloader to ensure correct system behaviour. > > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> This patch looks good for me but I have a couple of questions below. > --- > drivers/cpuidle/Kconfig | 8 +++ > drivers/cpuidle/Makefile | 1 + > drivers/cpuidle/dt_idle_states.c | 138 +++++++++++++++++++++++++++++++++++++++ > drivers/cpuidle/dt_idle_states.h | 5 ++ > 4 files changed, 152 insertions(+) > create mode 100644 drivers/cpuidle/dt_idle_states.c > create mode 100644 drivers/cpuidle/dt_idle_states.h > > diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig > index 1b96fb9..414e7a96 100644 > --- a/drivers/cpuidle/Kconfig > +++ b/drivers/cpuidle/Kconfig > @@ -30,6 +30,14 @@ config CPU_IDLE_GOV_MENU > bool "Menu governor (for tickless system)" > default y > > +config DT_IDLE_STATES > + bool "Idle states DT support" > + depends on ARM || ARM64 > + help > + Allows the CPU idle framework to initialize CPU idle drivers > + state data by using DT provided nodes compliant with idle states > + device tree bindings. > + Wouldn't make sense to make this as an hidden option and let the different drivers to set DT_IDLE_STATES if they depend on it ? > menu "ARM CPU Idle Drivers" > depends on ARM > source "drivers/cpuidle/Kconfig.arm" > diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile > index d8bb1ff..b27a062 100644 > --- a/drivers/cpuidle/Makefile > +++ b/drivers/cpuidle/Makefile > @@ -4,6 +4,7 @@ > > obj-y += cpuidle.o driver.o governor.o sysfs.o governors/ > obj-$(CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED) += coupled.o > +obj-$(CONFIG_DT_IDLE_STATES) += dt_idle_states.o > > ################################################################################## > # ARM SoC drivers > diff --git a/drivers/cpuidle/dt_idle_states.c b/drivers/cpuidle/dt_idle_states.c > new file mode 100644 > index 0000000..5413132 > --- /dev/null > +++ b/drivers/cpuidle/dt_idle_states.c > @@ -0,0 +1,138 @@ > +/* > + * DT idle states parsing code. > + * > + * Copyright (C) 2014 ARM Ltd. > + * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> > + * > + * 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. > + */ > + > +#define pr_fmt(fmt) "DT idle-states: " fmt > + > +#include <linux/cpuidle.h> > +#include <linux/cpumask.h> > +#include <linux/errno.h> > +#include <linux/kernel.h> > +#include <linux/module.h> > +#include <linux/of.h> > +#include <linux/of_device.h> > + > +#include "dt_idle_states.h" > + > +static int init_state_node(struct cpuidle_state *idle_state, > + struct device_node *state_node) > +{ > + int err; > + > + err = of_property_read_u32(state_node, "wakeup-latency-us", > + &idle_state->exit_latency); > + if (err) { > + u32 entry_latency, exit_latency; > + > + err = of_property_read_u32(state_node, "entry-latency-us", > + &entry_latency); > + if (err) { > + pr_debug(" * %s missing entry-latency-us property\n", > + state_node->full_name); > + return -EINVAL; > + } > + > + err = of_property_read_u32(state_node, "exit-latency-us", > + &exit_latency); > + if (err) { > + pr_debug(" * %s missing exit-latency-us property\n", > + state_node->full_name); > + return -EINVAL; > + } > + /* > + * If wakeup-latency-us is missing, default to entry+exit > + * latencies as defined in idle states bindings > + */ > + idle_state->exit_latency = entry_latency + exit_latency; > + } > + > + err = of_property_read_u32(state_node, "min-residency-us", > + &idle_state->target_residency); > + if (err) { > + pr_debug(" * %s missing min-residency-us property\n", > + state_node->full_name); > + return -EINVAL; > + } > + > + idle_state->flags = CPUIDLE_FLAG_TIME_VALID; > + if (of_property_read_bool(state_node, "local-timer-stop")) > + idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP; > + /* > + * TODO: > + * replace with kstrdup and pointer assignment when name > + * and desc become string pointers > + */ > + strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN - 1); > + strncpy(idle_state->desc, state_node->name, CPUIDLE_DESC_LEN - 1); > + return 0; > +} > + > +/** > + * dt_init_idle_driver() - Parse the DT idle states and initialize the > + * idle driver states array > + * > + * @drv: Pointer to CPU idle driver to be initialized > + * @start_idx: First idle state index to be initialized > + * > + * On success the states array in the cpuidle driver contains > + * initialized entries in the states array, starting from index start_idx. > + * > + * Return: > + * 0 on success > + * <0 on failure > + */ > +int dt_init_idle_driver(struct cpuidle_driver *drv, unsigned int start_idx) > +{ > + unsigned int i, state_idx = start_idx; > + struct cpuidle_state *idle_state; > + struct device_node *state_node, *cpu_node; > + > + > + if (state_idx >= CPUIDLE_STATE_MAX) > + return -EINVAL; > + /* > + * We get the idle states for the first logical cpu in the > + * driver mask. The kernel does not check idle states on all > + * cpus in the driver mask, they are assumed to be the same > + * by default. > + */ > + cpu_node = of_cpu_device_node_get(cpumask_first(drv->cpumask)); > + > + for (i = 0; ; i++) { > + int err; > + > + state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i); > + if (!state_node) > + break; > + > + if (state_idx == CPUIDLE_STATE_MAX) { > + pr_warn("State index reached static CPU idle driver states array size\n"); > + break; > + } > + > + idle_state = &drv->states[state_idx++]; > + err = init_state_node(idle_state, state_node); > + if (err) As the init_state_node error traces are in pr_debug level, a pr_err would help here IMO. > + return err; > + } > + > + /* > + * If no idle states are detected, return an error and let the idle > + * driver initialization fail accordingly since initializing a driver > + * with simple WFI as an idle state is equivalent to letting the > + * kernel run the default idle loop. > + */ > + if (!i) > + return -ENODATA; > + > + drv->state_count = state_idx; > + return 0; > +} > +EXPORT_SYMBOL_GPL(dt_init_idle_driver); > diff --git a/drivers/cpuidle/dt_idle_states.h b/drivers/cpuidle/dt_idle_states.h > new file mode 100644 > index 0000000..728c37c > --- /dev/null > +++ b/drivers/cpuidle/dt_idle_states.h > @@ -0,0 +1,5 @@ > +#ifndef __DT_IDLE_STATES > +#define __DT_IDLE_STATES > + > +int dt_init_idle_driver(struct cpuidle_driver *drv, unsigned int start_idx); > +#endif >
diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig index 1b96fb9..414e7a96 100644 --- a/drivers/cpuidle/Kconfig +++ b/drivers/cpuidle/Kconfig @@ -30,6 +30,14 @@ config CPU_IDLE_GOV_MENU bool "Menu governor (for tickless system)" default y +config DT_IDLE_STATES + bool "Idle states DT support" + depends on ARM || ARM64 + help + Allows the CPU idle framework to initialize CPU idle drivers + state data by using DT provided nodes compliant with idle states + device tree bindings. + menu "ARM CPU Idle Drivers" depends on ARM source "drivers/cpuidle/Kconfig.arm" diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile index d8bb1ff..b27a062 100644 --- a/drivers/cpuidle/Makefile +++ b/drivers/cpuidle/Makefile @@ -4,6 +4,7 @@ obj-y += cpuidle.o driver.o governor.o sysfs.o governors/ obj-$(CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED) += coupled.o +obj-$(CONFIG_DT_IDLE_STATES) += dt_idle_states.o ################################################################################## # ARM SoC drivers diff --git a/drivers/cpuidle/dt_idle_states.c b/drivers/cpuidle/dt_idle_states.c new file mode 100644 index 0000000..5413132 --- /dev/null +++ b/drivers/cpuidle/dt_idle_states.c @@ -0,0 +1,138 @@ +/* + * DT idle states parsing code. + * + * Copyright (C) 2014 ARM Ltd. + * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> + * + * 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. + */ + +#define pr_fmt(fmt) "DT idle-states: " fmt + +#include <linux/cpuidle.h> +#include <linux/cpumask.h> +#include <linux/errno.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/of_device.h> + +#include "dt_idle_states.h" + +static int init_state_node(struct cpuidle_state *idle_state, + struct device_node *state_node) +{ + int err; + + err = of_property_read_u32(state_node, "wakeup-latency-us", + &idle_state->exit_latency); + if (err) { + u32 entry_latency, exit_latency; + + err = of_property_read_u32(state_node, "entry-latency-us", + &entry_latency); + if (err) { + pr_debug(" * %s missing entry-latency-us property\n", + state_node->full_name); + return -EINVAL; + } + + err = of_property_read_u32(state_node, "exit-latency-us", + &exit_latency); + if (err) { + pr_debug(" * %s missing exit-latency-us property\n", + state_node->full_name); + return -EINVAL; + } + /* + * If wakeup-latency-us is missing, default to entry+exit + * latencies as defined in idle states bindings + */ + idle_state->exit_latency = entry_latency + exit_latency; + } + + err = of_property_read_u32(state_node, "min-residency-us", + &idle_state->target_residency); + if (err) { + pr_debug(" * %s missing min-residency-us property\n", + state_node->full_name); + return -EINVAL; + } + + idle_state->flags = CPUIDLE_FLAG_TIME_VALID; + if (of_property_read_bool(state_node, "local-timer-stop")) + idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP; + /* + * TODO: + * replace with kstrdup and pointer assignment when name + * and desc become string pointers + */ + strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN - 1); + strncpy(idle_state->desc, state_node->name, CPUIDLE_DESC_LEN - 1); + return 0; +} + +/** + * dt_init_idle_driver() - Parse the DT idle states and initialize the + * idle driver states array + * + * @drv: Pointer to CPU idle driver to be initialized + * @start_idx: First idle state index to be initialized + * + * On success the states array in the cpuidle driver contains + * initialized entries in the states array, starting from index start_idx. + * + * Return: + * 0 on success + * <0 on failure + */ +int dt_init_idle_driver(struct cpuidle_driver *drv, unsigned int start_idx) +{ + unsigned int i, state_idx = start_idx; + struct cpuidle_state *idle_state; + struct device_node *state_node, *cpu_node; + + + if (state_idx >= CPUIDLE_STATE_MAX) + return -EINVAL; + /* + * We get the idle states for the first logical cpu in the + * driver mask. The kernel does not check idle states on all + * cpus in the driver mask, they are assumed to be the same + * by default. + */ + cpu_node = of_cpu_device_node_get(cpumask_first(drv->cpumask)); + + for (i = 0; ; i++) { + int err; + + state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i); + if (!state_node) + break; + + if (state_idx == CPUIDLE_STATE_MAX) { + pr_warn("State index reached static CPU idle driver states array size\n"); + break; + } + + idle_state = &drv->states[state_idx++]; + err = init_state_node(idle_state, state_node); + if (err) + return err; + } + + /* + * If no idle states are detected, return an error and let the idle + * driver initialization fail accordingly since initializing a driver + * with simple WFI as an idle state is equivalent to letting the + * kernel run the default idle loop. + */ + if (!i) + return -ENODATA; + + drv->state_count = state_idx; + return 0; +} +EXPORT_SYMBOL_GPL(dt_init_idle_driver); diff --git a/drivers/cpuidle/dt_idle_states.h b/drivers/cpuidle/dt_idle_states.h new file mode 100644 index 0000000..728c37c --- /dev/null +++ b/drivers/cpuidle/dt_idle_states.h @@ -0,0 +1,5 @@ +#ifndef __DT_IDLE_STATES +#define __DT_IDLE_STATES + +int dt_init_idle_driver(struct cpuidle_driver *drv, unsigned int start_idx); +#endif
On most common ARM systems, the low-power states a CPU can be put into are not discoverable in HW and require device tree bindings to describe power down suspend operations and idle states parameters. In order to enable DT based idle states and configure idle drivers, this patch implements the bulk infrastructure required to parse the device tree idle states bindings and initialize the corresponding CPUidle driver states data. The parsing API accepts a start index that defines the first idle state that should be initialized by the parsing code in order to give new and legacy driver flexibility over which states should be parsed using the new DT mechanism. The idle states list is obtained from the first cpu in the driver cpumask, which implicitly means the parsing code expects idle states (and related list of phandles) to be the same for all CPUs in the CPUidle driver mask. The kernel does not check this assumption, it must be enforced by the bootloader to ensure correct system behaviour. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> --- drivers/cpuidle/Kconfig | 8 +++ drivers/cpuidle/Makefile | 1 + drivers/cpuidle/dt_idle_states.c | 138 +++++++++++++++++++++++++++++++++++++++ drivers/cpuidle/dt_idle_states.h | 5 ++ 4 files changed, 152 insertions(+) create mode 100644 drivers/cpuidle/dt_idle_states.c create mode 100644 drivers/cpuidle/dt_idle_states.h