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9f14da34 LP |
1 | /* |
2 | * DT idle states parsing code. | |
3 | * | |
4 | * Copyright (C) 2014 ARM Ltd. | |
5 | * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License version 2 as | |
9 | * published by the Free Software Foundation. | |
10 | */ | |
11 | ||
12 | #define pr_fmt(fmt) "DT idle-states: " fmt | |
13 | ||
14 | #include <linux/cpuidle.h> | |
15 | #include <linux/cpumask.h> | |
16 | #include <linux/errno.h> | |
17 | #include <linux/kernel.h> | |
18 | #include <linux/module.h> | |
19 | #include <linux/of.h> | |
20 | #include <linux/of_device.h> | |
21 | ||
22 | #include "dt_idle_states.h" | |
23 | ||
24 | static int init_state_node(struct cpuidle_state *idle_state, | |
25 | const struct of_device_id *matches, | |
26 | struct device_node *state_node) | |
27 | { | |
28 | int err; | |
29 | const struct of_device_id *match_id; | |
c00bc5df | 30 | const char *desc; |
9f14da34 LP |
31 | |
32 | match_id = of_match_node(matches, state_node); | |
33 | if (!match_id) | |
34 | return -ENODEV; | |
35 | /* | |
36 | * CPUidle drivers are expected to initialize the const void *data | |
37 | * pointer of the passed in struct of_device_id array to the idle | |
38 | * state enter function. | |
39 | */ | |
40 | idle_state->enter = match_id->data; | |
41 | ||
42 | err = of_property_read_u32(state_node, "wakeup-latency-us", | |
43 | &idle_state->exit_latency); | |
44 | if (err) { | |
45 | u32 entry_latency, exit_latency; | |
46 | ||
47 | err = of_property_read_u32(state_node, "entry-latency-us", | |
48 | &entry_latency); | |
49 | if (err) { | |
50 | pr_debug(" * %s missing entry-latency-us property\n", | |
51 | state_node->full_name); | |
52 | return -EINVAL; | |
53 | } | |
54 | ||
55 | err = of_property_read_u32(state_node, "exit-latency-us", | |
56 | &exit_latency); | |
57 | if (err) { | |
58 | pr_debug(" * %s missing exit-latency-us property\n", | |
59 | state_node->full_name); | |
60 | return -EINVAL; | |
61 | } | |
62 | /* | |
63 | * If wakeup-latency-us is missing, default to entry+exit | |
64 | * latencies as defined in idle states bindings | |
65 | */ | |
66 | idle_state->exit_latency = entry_latency + exit_latency; | |
67 | } | |
68 | ||
69 | err = of_property_read_u32(state_node, "min-residency-us", | |
70 | &idle_state->target_residency); | |
71 | if (err) { | |
72 | pr_debug(" * %s missing min-residency-us property\n", | |
73 | state_node->full_name); | |
74 | return -EINVAL; | |
75 | } | |
76 | ||
c00bc5df LP |
77 | err = of_property_read_string(state_node, "idle-state-name", &desc); |
78 | if (err) | |
79 | desc = state_node->name; | |
80 | ||
b82b6cca | 81 | idle_state->flags = 0; |
9f14da34 LP |
82 | if (of_property_read_bool(state_node, "local-timer-stop")) |
83 | idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP; | |
84 | /* | |
85 | * TODO: | |
86 | * replace with kstrdup and pointer assignment when name | |
87 | * and desc become string pointers | |
88 | */ | |
89 | strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN - 1); | |
c00bc5df | 90 | strncpy(idle_state->desc, desc, CPUIDLE_DESC_LEN - 1); |
9f14da34 LP |
91 | return 0; |
92 | } | |
93 | ||
94 | /* | |
95 | * Check that the idle state is uniform across all CPUs in the CPUidle driver | |
96 | * cpumask | |
97 | */ | |
98 | static bool idle_state_valid(struct device_node *state_node, unsigned int idx, | |
99 | const cpumask_t *cpumask) | |
100 | { | |
101 | int cpu; | |
102 | struct device_node *cpu_node, *curr_state_node; | |
103 | bool valid = true; | |
104 | ||
105 | /* | |
106 | * Compare idle state phandles for index idx on all CPUs in the | |
107 | * CPUidle driver cpumask. Start from next logical cpu following | |
108 | * cpumask_first(cpumask) since that's the CPU state_node was | |
109 | * retrieved from. If a mismatch is found bail out straight | |
110 | * away since we certainly hit a firmware misconfiguration. | |
111 | */ | |
112 | for (cpu = cpumask_next(cpumask_first(cpumask), cpumask); | |
113 | cpu < nr_cpu_ids; cpu = cpumask_next(cpu, cpumask)) { | |
114 | cpu_node = of_cpu_device_node_get(cpu); | |
115 | curr_state_node = of_parse_phandle(cpu_node, "cpu-idle-states", | |
116 | idx); | |
117 | if (state_node != curr_state_node) | |
118 | valid = false; | |
119 | ||
120 | of_node_put(curr_state_node); | |
121 | of_node_put(cpu_node); | |
122 | if (!valid) | |
123 | break; | |
124 | } | |
125 | ||
126 | return valid; | |
127 | } | |
128 | ||
129 | /** | |
130 | * dt_init_idle_driver() - Parse the DT idle states and initialize the | |
131 | * idle driver states array | |
132 | * @drv: Pointer to CPU idle driver to be initialized | |
133 | * @matches: Array of of_device_id match structures to search in for | |
134 | * compatible idle state nodes. The data pointer for each valid | |
135 | * struct of_device_id entry in the matches array must point to | |
136 | * a function with the following signature, that corresponds to | |
137 | * the CPUidle state enter function signature: | |
138 | * | |
139 | * int (*)(struct cpuidle_device *dev, | |
140 | * struct cpuidle_driver *drv, | |
141 | * int index); | |
142 | * | |
143 | * @start_idx: First idle state index to be initialized | |
144 | * | |
145 | * If DT idle states are detected and are valid the state count and states | |
146 | * array entries in the cpuidle driver are initialized accordingly starting | |
147 | * from index start_idx. | |
148 | * | |
149 | * Return: number of valid DT idle states parsed, <0 on failure | |
150 | */ | |
151 | int dt_init_idle_driver(struct cpuidle_driver *drv, | |
152 | const struct of_device_id *matches, | |
153 | unsigned int start_idx) | |
154 | { | |
155 | struct cpuidle_state *idle_state; | |
156 | struct device_node *state_node, *cpu_node; | |
157 | int i, err = 0; | |
158 | const cpumask_t *cpumask; | |
159 | unsigned int state_idx = start_idx; | |
160 | ||
161 | if (state_idx >= CPUIDLE_STATE_MAX) | |
162 | return -EINVAL; | |
163 | /* | |
164 | * We get the idle states for the first logical cpu in the | |
165 | * driver mask (or cpu_possible_mask if the driver cpumask is not set) | |
166 | * and we check through idle_state_valid() if they are uniform | |
167 | * across CPUs, otherwise we hit a firmware misconfiguration. | |
168 | */ | |
169 | cpumask = drv->cpumask ? : cpu_possible_mask; | |
170 | cpu_node = of_cpu_device_node_get(cpumask_first(cpumask)); | |
171 | ||
172 | for (i = 0; ; i++) { | |
173 | state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i); | |
174 | if (!state_node) | |
175 | break; | |
176 | ||
97735da0 LP |
177 | if (!of_device_is_available(state_node)) |
178 | continue; | |
179 | ||
9f14da34 LP |
180 | if (!idle_state_valid(state_node, i, cpumask)) { |
181 | pr_warn("%s idle state not valid, bailing out\n", | |
182 | state_node->full_name); | |
183 | err = -EINVAL; | |
184 | break; | |
185 | } | |
186 | ||
187 | if (state_idx == CPUIDLE_STATE_MAX) { | |
188 | pr_warn("State index reached static CPU idle driver states array size\n"); | |
189 | break; | |
190 | } | |
191 | ||
192 | idle_state = &drv->states[state_idx++]; | |
193 | err = init_state_node(idle_state, matches, state_node); | |
194 | if (err) { | |
195 | pr_err("Parsing idle state node %s failed with err %d\n", | |
196 | state_node->full_name, err); | |
197 | err = -EINVAL; | |
198 | break; | |
199 | } | |
200 | of_node_put(state_node); | |
201 | } | |
202 | ||
203 | of_node_put(state_node); | |
204 | of_node_put(cpu_node); | |
205 | if (err) | |
206 | return err; | |
207 | /* | |
208 | * Update the driver state count only if some valid DT idle states | |
209 | * were detected | |
210 | */ | |
211 | if (i) | |
212 | drv->state_count = state_idx; | |
213 | ||
214 | /* | |
215 | * Return the number of present and valid DT idle states, which can | |
216 | * also be 0 on platforms with missing DT idle states or legacy DT | |
217 | * configuration predating the DT idle states bindings. | |
218 | */ | |
219 | return i; | |
220 | } | |
221 | EXPORT_SYMBOL_GPL(dt_init_idle_driver); |