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git.proxmox.com Git - mirror_ubuntu-jammy-kernel.git/blob - drivers/cpuidle/dt_idle_states.c
1 // SPDX-License-Identifier: GPL-2.0-only
3 * DT idle states parsing code.
5 * Copyright (C) 2014 ARM Ltd.
6 * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
9 #define pr_fmt(fmt) "DT idle-states: " fmt
11 #include <linux/cpuidle.h>
12 #include <linux/cpumask.h>
13 #include <linux/errno.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
17 #include <linux/of_device.h>
19 #include "dt_idle_states.h"
21 static int init_state_node(struct cpuidle_state
*idle_state
,
22 const struct of_device_id
*match_id
,
23 struct device_node
*state_node
)
29 * CPUidle drivers are expected to initialize the const void *data
30 * pointer of the passed in struct of_device_id array to the idle
31 * state enter function.
33 idle_state
->enter
= match_id
->data
;
35 * Since this is not a "coupled" state, it's safe to assume interrupts
36 * won't be enabled when it exits allowing the tick to be frozen
37 * safely. So enter() can be also enter_s2idle() callback.
39 idle_state
->enter_s2idle
= match_id
->data
;
41 err
= of_property_read_u32(state_node
, "wakeup-latency-us",
42 &idle_state
->exit_latency
);
44 u32 entry_latency
, exit_latency
;
46 err
= of_property_read_u32(state_node
, "entry-latency-us",
49 pr_debug(" * %pOF missing entry-latency-us property\n",
54 err
= of_property_read_u32(state_node
, "exit-latency-us",
57 pr_debug(" * %pOF missing exit-latency-us property\n",
62 * If wakeup-latency-us is missing, default to entry+exit
63 * latencies as defined in idle states bindings
65 idle_state
->exit_latency
= entry_latency
+ exit_latency
;
68 err
= of_property_read_u32(state_node
, "min-residency-us",
69 &idle_state
->target_residency
);
71 pr_debug(" * %pOF missing min-residency-us property\n",
76 err
= of_property_read_string(state_node
, "idle-state-name", &desc
);
78 desc
= state_node
->name
;
80 idle_state
->flags
= 0;
81 if (of_property_read_bool(state_node
, "local-timer-stop"))
82 idle_state
->flags
|= CPUIDLE_FLAG_TIMER_STOP
;
85 * replace with kstrdup and pointer assignment when name
86 * and desc become string pointers
88 strncpy(idle_state
->name
, state_node
->name
, CPUIDLE_NAME_LEN
- 1);
89 strncpy(idle_state
->desc
, desc
, CPUIDLE_DESC_LEN
- 1);
94 * Check that the idle state is uniform across all CPUs in the CPUidle driver
97 static bool idle_state_valid(struct device_node
*state_node
, unsigned int idx
,
98 const cpumask_t
*cpumask
)
101 struct device_node
*cpu_node
, *curr_state_node
;
105 * Compare idle state phandles for index idx on all CPUs in the
106 * CPUidle driver cpumask. Start from next logical cpu following
107 * cpumask_first(cpumask) since that's the CPU state_node was
108 * retrieved from. If a mismatch is found bail out straight
109 * away since we certainly hit a firmware misconfiguration.
111 for (cpu
= cpumask_next(cpumask_first(cpumask
), cpumask
);
112 cpu
< nr_cpu_ids
; cpu
= cpumask_next(cpu
, cpumask
)) {
113 cpu_node
= of_cpu_device_node_get(cpu
);
114 curr_state_node
= of_get_cpu_state_node(cpu_node
, idx
);
115 if (state_node
!= curr_state_node
)
118 of_node_put(curr_state_node
);
119 of_node_put(cpu_node
);
128 * dt_init_idle_driver() - Parse the DT idle states and initialize the
129 * idle driver states array
130 * @drv: Pointer to CPU idle driver to be initialized
131 * @matches: Array of of_device_id match structures to search in for
132 * compatible idle state nodes. The data pointer for each valid
133 * struct of_device_id entry in the matches array must point to
134 * a function with the following signature, that corresponds to
135 * the CPUidle state enter function signature:
137 * int (*)(struct cpuidle_device *dev,
138 * struct cpuidle_driver *drv,
141 * @start_idx: First idle state index to be initialized
143 * If DT idle states are detected and are valid the state count and states
144 * array entries in the cpuidle driver are initialized accordingly starting
145 * from index start_idx.
147 * Return: number of valid DT idle states parsed, <0 on failure
149 int dt_init_idle_driver(struct cpuidle_driver
*drv
,
150 const struct of_device_id
*matches
,
151 unsigned int start_idx
)
153 struct cpuidle_state
*idle_state
;
154 struct device_node
*state_node
, *cpu_node
;
155 const struct of_device_id
*match_id
;
157 const cpumask_t
*cpumask
;
158 unsigned int state_idx
= start_idx
;
160 if (state_idx
>= CPUIDLE_STATE_MAX
)
163 * We get the idle states for the first logical cpu in the
164 * driver mask (or cpu_possible_mask if the driver cpumask is not set)
165 * and we check through idle_state_valid() if they are uniform
166 * across CPUs, otherwise we hit a firmware misconfiguration.
168 cpumask
= drv
->cpumask
? : cpu_possible_mask
;
169 cpu_node
= of_cpu_device_node_get(cpumask_first(cpumask
));
172 state_node
= of_get_cpu_state_node(cpu_node
, i
);
176 match_id
= of_match_node(matches
, state_node
);
182 if (!of_device_is_available(state_node
)) {
183 of_node_put(state_node
);
187 if (!idle_state_valid(state_node
, i
, cpumask
)) {
188 pr_warn("%pOF idle state not valid, bailing out\n",
194 if (state_idx
== CPUIDLE_STATE_MAX
) {
195 pr_warn("State index reached static CPU idle driver states array size\n");
199 idle_state
= &drv
->states
[state_idx
++];
200 err
= init_state_node(idle_state
, match_id
, state_node
);
202 pr_err("Parsing idle state node %pOF failed with err %d\n",
207 of_node_put(state_node
);
210 of_node_put(state_node
);
211 of_node_put(cpu_node
);
215 * Update the driver state count only if some valid DT idle states
219 drv
->state_count
= state_idx
;
222 * Return the number of present and valid DT idle states, which can
223 * also be 0 on platforms with missing DT idle states or legacy DT
224 * configuration predating the DT idle states bindings.
228 EXPORT_SYMBOL_GPL(dt_init_idle_driver
);