On Wed, Sep 03, 2014 at 02:25:39PM +0100, Daniel Lezcano wrote:
> On 09/01/2014 05:28 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 node(s) is obtained from the phandle list of the first cpu
> > in the driver cpumask; the kernel checks that the idle state node phandle
> > is the same for all CPUs in the driver cpumask before declaring the idle state
> > as valid and start parsing its content.
> >
> > The idle state enter function pointer is initialized through DT match
> > structures passed in by the CPUidle driver, so that ARM legacy code can
> > cope with platform specific idle entry method based on compatible
> > string matching and the code used to initialize the enter function pointer
> > can be moved to the DT generic layer.
> >
> > Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
> > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
>
> nice !
>
> Acked-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
Thanks !
Lorenzo
> > ---
> > drivers/cpuidle/Kconfig | 3 +
> > drivers/cpuidle/Makefile | 1 +
> > drivers/cpuidle/dt_idle_states.c | 213 +++++++++++++++++++++++++++++++++++++++
> > drivers/cpuidle/dt_idle_states.h | 7 ++
> > 4 files changed, 224 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 32748c3..8deb934 100644
> > --- a/drivers/cpuidle/Kconfig
> > +++ b/drivers/cpuidle/Kconfig
> > @@ -25,6 +25,9 @@ config CPU_IDLE_GOV_MENU
> > bool "Menu governor (for tickless system)"
> > default y
> >
> > +config DT_IDLE_STATES
> > + bool
> > +
> > menu "ARM CPU Idle Drivers"
> > depends on ARM
> > source "drivers/cpuidle/Kconfig.arm"
> > diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
> > index 11edb31..002b653 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..52f4d11
> > --- /dev/null
> > +++ b/drivers/cpuidle/dt_idle_states.c
> > @@ -0,0 +1,213 @@
> > +/*
> > + * DT idle states parsing code.
> > + *
> > + * Copyright (C) 2014 ARM Ltd.
> > + * Author: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> > + *
> > + * 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,
> > + const struct of_device_id *matches,
> > + struct device_node *state_node)
> > +{
> > + int err;
> > + const struct of_device_id *match_id;
> > +
> > + match_id = of_match_node(matches, state_node);
> > + if (!match_id)
> > + return -ENODEV;
> > + /*
> > + * CPUidle drivers are expected to initialize the const void *data
> > + * pointer of the passed in struct of_device_id array to the idle
> > + * state enter function.
> > + */
> > + idle_state->enter = match_id->data;
> > +
> > + 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;
> > +}
> > +
> > +/*
> > + * Check that the idle state is uniform across all CPUs in the CPUidle driver
> > + * cpumask
> > + */
> > +static bool idle_state_valid(struct device_node *state_node, unsigned int idx,
> > + const cpumask_t *cpumask)
> > +{
> > + int cpu;
> > + struct device_node *cpu_node, *curr_state_node;
> > + bool valid = true;
> > +
> > + /*
> > + * Compare idle state phandles for index idx on all CPUs in the
> > + * CPUidle driver cpumask. Start from next logical cpu following
> > + * cpumask_first(cpumask) since that's the CPU state_node was
> > + * retrieved from. If a mismatch is found bail out straight
> > + * away since we certainly hit a firmware misconfiguration.
> > + */
> > + for (cpu = cpumask_next(cpumask_first(cpumask), cpumask);
> > + cpu < nr_cpu_ids; cpu = cpumask_next(cpu, cpumask)) {
> > + cpu_node = of_cpu_device_node_get(cpu);
> > + curr_state_node = of_parse_phandle(cpu_node, "cpu-idle-states",
> > + idx);
> > + if (state_node != curr_state_node)
> > + valid = false;
> > +
> > + of_node_put(curr_state_node);
> > + of_node_put(cpu_node);
> > + if (!valid)
> > + break;
> > + }
> > +
> > + return valid;
> > +}
> > +
> > +/**
> > + * 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
> > + * @matches: Array of of_device_id match structures to search in for
> > + * compatible idle state nodes. The data pointer for each valid
> > + * struct of_device_id entry in the matches array must point to
> > + * a function with the following signature, that corresponds to
> > + * the CPUidle state enter function signature:
> > + *
> > + * int (*)(struct cpuidle_device *dev,
> > + * struct cpuidle_driver *drv,
> > + * int index);
> > + *
> > + * @start_idx: First idle state index to be initialized
> > + *
> > + * If DT idle states are detected and are valid the state count and states
> > + * array entries in the cpuidle driver are initialized accordingly starting
> > + * from index start_idx.
> > + *
> > + * Return: number of valid DT idle states parsed, <0 on failure
> > + */
> > +int dt_init_idle_driver(struct cpuidle_driver *drv,
> > + const struct of_device_id *matches,
> > + unsigned int start_idx)
> > +{
> > + struct cpuidle_state *idle_state;
> > + struct device_node *state_node, *cpu_node;
> > + int i, err = 0;
> > + const cpumask_t *cpumask;
> > + unsigned int state_idx = start_idx;
> > +
> > + if (state_idx >= CPUIDLE_STATE_MAX)
> > + return -EINVAL;
> > + /*
> > + * We get the idle states for the first logical cpu in the
> > + * driver mask (or cpu_possible_mask if the driver cpumask is not set)
> > + * and we check through idle_state_valid() if they are uniform
> > + * across CPUs, otherwise we hit a firmware misconfiguration.
> > + */
> > + cpumask = drv->cpumask ? : cpu_possible_mask;
> > + cpu_node = of_cpu_device_node_get(cpumask_first(cpumask));
> > +
> > + for (i = 0; ; i++) {
> > + state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i);
> > + if (!state_node)
> > + break;
> > +
> > + if (!idle_state_valid(state_node, i, cpumask)) {
> > + pr_warn("%s idle state not valid, bailing out\n",
> > + state_node->full_name);
> > + err = -EINVAL;
> > + 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, matches, state_node);
> > + if (err) {
> > + pr_err("Parsing idle state node %s failed with err %d\n",
> > + state_node->full_name, err);
> > + err = -EINVAL;
> > + break;
> > + }
> > + of_node_put(state_node);
> > + }
> > +
> > + of_node_put(state_node);
> > + of_node_put(cpu_node);
> > + if (err)
> > + return err;
> > + /*
> > + * Update the driver state count only if some valid DT idle states
> > + * were detected
> > + */
> > + if (i)
> > + drv->state_count = state_idx;
> > +
> > + /*
> > + * Return the number of present and valid DT idle states, which can
> > + * also be 0 on platforms with missing DT idle states or legacy DT
> > + * configuration predating the DT idle states bindings.
> > + */
> > + return i;
> > +}
> > +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..4818134
> > --- /dev/null
> > +++ b/drivers/cpuidle/dt_idle_states.h
> > @@ -0,0 +1,7 @@
> > +#ifndef __DT_IDLE_STATES
> > +#define __DT_IDLE_STATES
> > +
> > +int dt_init_idle_driver(struct cpuidle_driver *drv,
> > + const struct of_device_id *matches,
> > + unsigned int start_idx);
> > +#endif
> >
>
>
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