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d2912cb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
9f14da34 LP |
2 | /* |
3 | * DT idle states parsing code. | |
4 | * | |
5 | * Copyright (C) 2014 ARM Ltd. | |
6 | * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> | |
9f14da34 LP |
7 | */ |
8 | ||
9 | #define pr_fmt(fmt) "DT idle-states: " fmt | |
10 | ||
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> | |
16 | #include <linux/of.h> | |
17 | #include <linux/of_device.h> | |
18 | ||
19 | #include "dt_idle_states.h" | |
20 | ||
21 | static int init_state_node(struct cpuidle_state *idle_state, | |
db10945c | 22 | const struct of_device_id *match_id, |
9f14da34 LP |
23 | struct device_node *state_node) |
24 | { | |
25 | int err; | |
c00bc5df | 26 | const char *desc; |
9f14da34 | 27 | |
9f14da34 LP |
28 | /* |
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. | |
32 | */ | |
33 | idle_state->enter = match_id->data; | |
a94e502c SH |
34 | /* |
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 | |
28ba086e | 37 | * safely. So enter() can be also enter_s2idle() callback. |
a94e502c | 38 | */ |
28ba086e | 39 | idle_state->enter_s2idle = match_id->data; |
9f14da34 LP |
40 | |
41 | err = of_property_read_u32(state_node, "wakeup-latency-us", | |
42 | &idle_state->exit_latency); | |
43 | if (err) { | |
44 | u32 entry_latency, exit_latency; | |
45 | ||
46 | err = of_property_read_u32(state_node, "entry-latency-us", | |
47 | &entry_latency); | |
48 | if (err) { | |
84dc4141 RH |
49 | pr_debug(" * %pOF missing entry-latency-us property\n", |
50 | state_node); | |
9f14da34 LP |
51 | return -EINVAL; |
52 | } | |
53 | ||
54 | err = of_property_read_u32(state_node, "exit-latency-us", | |
55 | &exit_latency); | |
56 | if (err) { | |
84dc4141 RH |
57 | pr_debug(" * %pOF missing exit-latency-us property\n", |
58 | state_node); | |
9f14da34 LP |
59 | return -EINVAL; |
60 | } | |
61 | /* | |
62 | * If wakeup-latency-us is missing, default to entry+exit | |
63 | * latencies as defined in idle states bindings | |
64 | */ | |
65 | idle_state->exit_latency = entry_latency + exit_latency; | |
66 | } | |
67 | ||
68 | err = of_property_read_u32(state_node, "min-residency-us", | |
69 | &idle_state->target_residency); | |
70 | if (err) { | |
84dc4141 RH |
71 | pr_debug(" * %pOF missing min-residency-us property\n", |
72 | state_node); | |
9f14da34 LP |
73 | return -EINVAL; |
74 | } | |
75 | ||
c00bc5df LP |
76 | err = of_property_read_string(state_node, "idle-state-name", &desc); |
77 | if (err) | |
78 | desc = state_node->name; | |
79 | ||
b82b6cca | 80 | idle_state->flags = 0; |
9f14da34 LP |
81 | if (of_property_read_bool(state_node, "local-timer-stop")) |
82 | idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP; | |
83 | /* | |
84 | * TODO: | |
85 | * replace with kstrdup and pointer assignment when name | |
86 | * and desc become string pointers | |
87 | */ | |
88 | strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN - 1); | |
c00bc5df | 89 | strncpy(idle_state->desc, desc, CPUIDLE_DESC_LEN - 1); |
9f14da34 LP |
90 | return 0; |
91 | } | |
92 | ||
93 | /* | |
94 | * Check that the idle state is uniform across all CPUs in the CPUidle driver | |
95 | * cpumask | |
96 | */ | |
97 | static bool idle_state_valid(struct device_node *state_node, unsigned int idx, | |
98 | const cpumask_t *cpumask) | |
99 | { | |
100 | int cpu; | |
101 | struct device_node *cpu_node, *curr_state_node; | |
102 | bool valid = true; | |
103 | ||
104 | /* | |
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. | |
110 | */ | |
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); | |
778f173e | 114 | curr_state_node = of_get_cpu_state_node(cpu_node, idx); |
9f14da34 LP |
115 | if (state_node != curr_state_node) |
116 | valid = false; | |
117 | ||
118 | of_node_put(curr_state_node); | |
119 | of_node_put(cpu_node); | |
120 | if (!valid) | |
121 | break; | |
122 | } | |
123 | ||
124 | return valid; | |
125 | } | |
126 | ||
127 | /** | |
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: | |
136 | * | |
137 | * int (*)(struct cpuidle_device *dev, | |
138 | * struct cpuidle_driver *drv, | |
139 | * int index); | |
140 | * | |
141 | * @start_idx: First idle state index to be initialized | |
142 | * | |
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. | |
146 | * | |
147 | * Return: number of valid DT idle states parsed, <0 on failure | |
148 | */ | |
149 | int dt_init_idle_driver(struct cpuidle_driver *drv, | |
150 | const struct of_device_id *matches, | |
151 | unsigned int start_idx) | |
152 | { | |
153 | struct cpuidle_state *idle_state; | |
154 | struct device_node *state_node, *cpu_node; | |
db10945c | 155 | const struct of_device_id *match_id; |
9f14da34 LP |
156 | int i, err = 0; |
157 | const cpumask_t *cpumask; | |
158 | unsigned int state_idx = start_idx; | |
159 | ||
160 | if (state_idx >= CPUIDLE_STATE_MAX) | |
161 | return -EINVAL; | |
162 | /* | |
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. | |
167 | */ | |
168 | cpumask = drv->cpumask ? : cpu_possible_mask; | |
169 | cpu_node = of_cpu_device_node_get(cpumask_first(cpumask)); | |
170 | ||
171 | for (i = 0; ; i++) { | |
778f173e | 172 | state_node = of_get_cpu_state_node(cpu_node, i); |
9f14da34 LP |
173 | if (!state_node) |
174 | break; | |
175 | ||
db10945c JL |
176 | match_id = of_match_node(matches, state_node); |
177 | if (!match_id) { | |
178 | err = -ENODEV; | |
179 | break; | |
180 | } | |
181 | ||
b2cdd8e1 CJ |
182 | if (!of_device_is_available(state_node)) { |
183 | of_node_put(state_node); | |
97735da0 | 184 | continue; |
b2cdd8e1 | 185 | } |
97735da0 | 186 | |
9f14da34 | 187 | if (!idle_state_valid(state_node, i, cpumask)) { |
84dc4141 RH |
188 | pr_warn("%pOF idle state not valid, bailing out\n", |
189 | state_node); | |
9f14da34 LP |
190 | err = -EINVAL; |
191 | break; | |
192 | } | |
193 | ||
194 | if (state_idx == CPUIDLE_STATE_MAX) { | |
195 | pr_warn("State index reached static CPU idle driver states array size\n"); | |
196 | break; | |
197 | } | |
198 | ||
199 | idle_state = &drv->states[state_idx++]; | |
db10945c | 200 | err = init_state_node(idle_state, match_id, state_node); |
9f14da34 | 201 | if (err) { |
84dc4141 RH |
202 | pr_err("Parsing idle state node %pOF failed with err %d\n", |
203 | state_node, err); | |
9f14da34 LP |
204 | err = -EINVAL; |
205 | break; | |
206 | } | |
207 | of_node_put(state_node); | |
208 | } | |
209 | ||
210 | of_node_put(state_node); | |
211 | of_node_put(cpu_node); | |
212 | if (err) | |
213 | return err; | |
214 | /* | |
215 | * Update the driver state count only if some valid DT idle states | |
216 | * were detected | |
217 | */ | |
218 | if (i) | |
219 | drv->state_count = state_idx; | |
220 | ||
221 | /* | |
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. | |
225 | */ | |
226 | return i; | |
227 | } | |
228 | EXPORT_SYMBOL_GPL(dt_init_idle_driver); |