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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; | |
30 | ||
31 | match_id = of_match_node(matches, state_node); | |
32 | if (!match_id) | |
33 | return -ENODEV; | |
34 | /* | |
35 | * CPUidle drivers are expected to initialize the const void *data | |
36 | * pointer of the passed in struct of_device_id array to the idle | |
37 | * state enter function. | |
38 | */ | |
39 | idle_state->enter = match_id->data; | |
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) { | |
49 | pr_debug(" * %s missing entry-latency-us property\n", | |
50 | state_node->full_name); | |
51 | return -EINVAL; | |
52 | } | |
53 | ||
54 | err = of_property_read_u32(state_node, "exit-latency-us", | |
55 | &exit_latency); | |
56 | if (err) { | |
57 | pr_debug(" * %s missing exit-latency-us property\n", | |
58 | state_node->full_name); | |
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) { | |
71 | pr_debug(" * %s missing min-residency-us property\n", | |
72 | state_node->full_name); | |
73 | return -EINVAL; | |
74 | } | |
75 | ||
76 | idle_state->flags = CPUIDLE_FLAG_TIME_VALID; | |
77 | if (of_property_read_bool(state_node, "local-timer-stop")) | |
78 | idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP; | |
79 | /* | |
80 | * TODO: | |
81 | * replace with kstrdup and pointer assignment when name | |
82 | * and desc become string pointers | |
83 | */ | |
84 | strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN - 1); | |
85 | strncpy(idle_state->desc, state_node->name, CPUIDLE_DESC_LEN - 1); | |
86 | return 0; | |
87 | } | |
88 | ||
89 | /* | |
90 | * Check that the idle state is uniform across all CPUs in the CPUidle driver | |
91 | * cpumask | |
92 | */ | |
93 | static bool idle_state_valid(struct device_node *state_node, unsigned int idx, | |
94 | const cpumask_t *cpumask) | |
95 | { | |
96 | int cpu; | |
97 | struct device_node *cpu_node, *curr_state_node; | |
98 | bool valid = true; | |
99 | ||
100 | /* | |
101 | * Compare idle state phandles for index idx on all CPUs in the | |
102 | * CPUidle driver cpumask. Start from next logical cpu following | |
103 | * cpumask_first(cpumask) since that's the CPU state_node was | |
104 | * retrieved from. If a mismatch is found bail out straight | |
105 | * away since we certainly hit a firmware misconfiguration. | |
106 | */ | |
107 | for (cpu = cpumask_next(cpumask_first(cpumask), cpumask); | |
108 | cpu < nr_cpu_ids; cpu = cpumask_next(cpu, cpumask)) { | |
109 | cpu_node = of_cpu_device_node_get(cpu); | |
110 | curr_state_node = of_parse_phandle(cpu_node, "cpu-idle-states", | |
111 | idx); | |
112 | if (state_node != curr_state_node) | |
113 | valid = false; | |
114 | ||
115 | of_node_put(curr_state_node); | |
116 | of_node_put(cpu_node); | |
117 | if (!valid) | |
118 | break; | |
119 | } | |
120 | ||
121 | return valid; | |
122 | } | |
123 | ||
124 | /** | |
125 | * dt_init_idle_driver() - Parse the DT idle states and initialize the | |
126 | * idle driver states array | |
127 | * @drv: Pointer to CPU idle driver to be initialized | |
128 | * @matches: Array of of_device_id match structures to search in for | |
129 | * compatible idle state nodes. The data pointer for each valid | |
130 | * struct of_device_id entry in the matches array must point to | |
131 | * a function with the following signature, that corresponds to | |
132 | * the CPUidle state enter function signature: | |
133 | * | |
134 | * int (*)(struct cpuidle_device *dev, | |
135 | * struct cpuidle_driver *drv, | |
136 | * int index); | |
137 | * | |
138 | * @start_idx: First idle state index to be initialized | |
139 | * | |
140 | * If DT idle states are detected and are valid the state count and states | |
141 | * array entries in the cpuidle driver are initialized accordingly starting | |
142 | * from index start_idx. | |
143 | * | |
144 | * Return: number of valid DT idle states parsed, <0 on failure | |
145 | */ | |
146 | int dt_init_idle_driver(struct cpuidle_driver *drv, | |
147 | const struct of_device_id *matches, | |
148 | unsigned int start_idx) | |
149 | { | |
150 | struct cpuidle_state *idle_state; | |
151 | struct device_node *state_node, *cpu_node; | |
152 | int i, err = 0; | |
153 | const cpumask_t *cpumask; | |
154 | unsigned int state_idx = start_idx; | |
155 | ||
156 | if (state_idx >= CPUIDLE_STATE_MAX) | |
157 | return -EINVAL; | |
158 | /* | |
159 | * We get the idle states for the first logical cpu in the | |
160 | * driver mask (or cpu_possible_mask if the driver cpumask is not set) | |
161 | * and we check through idle_state_valid() if they are uniform | |
162 | * across CPUs, otherwise we hit a firmware misconfiguration. | |
163 | */ | |
164 | cpumask = drv->cpumask ? : cpu_possible_mask; | |
165 | cpu_node = of_cpu_device_node_get(cpumask_first(cpumask)); | |
166 | ||
167 | for (i = 0; ; i++) { | |
168 | state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i); | |
169 | if (!state_node) | |
170 | break; | |
171 | ||
172 | if (!idle_state_valid(state_node, i, cpumask)) { | |
173 | pr_warn("%s idle state not valid, bailing out\n", | |
174 | state_node->full_name); | |
175 | err = -EINVAL; | |
176 | break; | |
177 | } | |
178 | ||
179 | if (state_idx == CPUIDLE_STATE_MAX) { | |
180 | pr_warn("State index reached static CPU idle driver states array size\n"); | |
181 | break; | |
182 | } | |
183 | ||
184 | idle_state = &drv->states[state_idx++]; | |
185 | err = init_state_node(idle_state, matches, state_node); | |
186 | if (err) { | |
187 | pr_err("Parsing idle state node %s failed with err %d\n", | |
188 | state_node->full_name, err); | |
189 | err = -EINVAL; | |
190 | break; | |
191 | } | |
192 | of_node_put(state_node); | |
193 | } | |
194 | ||
195 | of_node_put(state_node); | |
196 | of_node_put(cpu_node); | |
197 | if (err) | |
198 | return err; | |
199 | /* | |
200 | * Update the driver state count only if some valid DT idle states | |
201 | * were detected | |
202 | */ | |
203 | if (i) | |
204 | drv->state_count = state_idx; | |
205 | ||
206 | /* | |
207 | * Return the number of present and valid DT idle states, which can | |
208 | * also be 0 on platforms with missing DT idle states or legacy DT | |
209 | * configuration predating the DT idle states bindings. | |
210 | */ | |
211 | return i; | |
212 | } | |
213 | EXPORT_SYMBOL_GPL(dt_init_idle_driver); |