// SPDX-License-Identifier: GPL-2.0-only /* * DT idle states parsing code. * * Copyright (C) 2014 ARM Ltd. * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> */ #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 *match_id, struct device_node *state_node) { int err; const char *desc; /* * 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; /* * Since this is not a "coupled" state, it's safe to assume interrupts * won't be enabled when it exits allowing the tick to be frozen * safely. So enter() can be also enter_s2idle() callback. */ idle_state->enter_s2idle = 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(" * %pOF missing entry-latency-us property\n", state_node); return -EINVAL; } err = of_property_read_u32(state_node, "exit-latency-us", &exit_latency); if (err) { pr_debug(" * %pOF missing exit-latency-us property\n", state_node); 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(" * %pOF missing min-residency-us property\n", state_node); 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_get_cpu_state_node(cpu_node, 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; const struct of_device_id *match_id; 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_get_cpu_state_node(cpu_node, i); if (!state_node) break; match_id = of_match_node(matches, state_node); if (!match_id) { err = -ENODEV; break; } if (!of_device_is_available(state_node)) { of_node_put(state_node); continue; } if (!idle_state_valid(state_node, i, cpumask)) { pr_warn("%pOF idle state not valid, bailing out\n", state_node); 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, match_id, state_node); if (err) { pr_err("Parsing idle state node %pOF failed with err %d\n", state_node, 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);