--- /dev/null
+/*
+ * 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,
+ const struct of_device_id *matches,
+ struct device_node *state_node)
+{
+ int err;
+ const struct of_device_id *match_id;
+ const char *desc;
+
+ 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;
+ }
+
+ err = of_property_read_string(state_node, "idle-state-name", &desc);
+ if (err)
+ desc = state_node->name;
+
+ idle_state->flags = 0;
+ 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, desc, 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 (!of_device_is_available(state_node))
+ continue;
+
+ 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);
Code Review / kvmfornfv.git / blobdiff