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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; | |
a94e502c SH |
41 | /* |
42 | * Since this is not a "coupled" state, it's safe to assume interrupts | |
43 | * won't be enabled when it exits allowing the tick to be frozen | |
28ba086e | 44 | * safely. So enter() can be also enter_s2idle() callback. |
a94e502c | 45 | */ |
28ba086e | 46 | idle_state->enter_s2idle = match_id->data; |
9f14da34 LP |
47 | |
48 | err = of_property_read_u32(state_node, "wakeup-latency-us", | |
49 | &idle_state->exit_latency); | |
50 | if (err) { | |
51 | u32 entry_latency, exit_latency; | |
52 | ||
53 | err = of_property_read_u32(state_node, "entry-latency-us", | |
54 | &entry_latency); | |
55 | if (err) { | |
84dc4141 RH |
56 | pr_debug(" * %pOF missing entry-latency-us property\n", |
57 | state_node); | |
9f14da34 LP |
58 | return -EINVAL; |
59 | } | |
60 | ||
61 | err = of_property_read_u32(state_node, "exit-latency-us", | |
62 | &exit_latency); | |
63 | if (err) { | |
84dc4141 RH |
64 | pr_debug(" * %pOF missing exit-latency-us property\n", |
65 | state_node); | |
9f14da34 LP |
66 | return -EINVAL; |
67 | } | |
68 | /* | |
69 | * If wakeup-latency-us is missing, default to entry+exit | |
70 | * latencies as defined in idle states bindings | |
71 | */ | |
72 | idle_state->exit_latency = entry_latency + exit_latency; | |
73 | } | |
74 | ||
75 | err = of_property_read_u32(state_node, "min-residency-us", | |
76 | &idle_state->target_residency); | |
77 | if (err) { | |
84dc4141 RH |
78 | pr_debug(" * %pOF missing min-residency-us property\n", |
79 | state_node); | |
9f14da34 LP |
80 | return -EINVAL; |
81 | } | |
82 | ||
c00bc5df LP |
83 | err = of_property_read_string(state_node, "idle-state-name", &desc); |
84 | if (err) | |
85 | desc = state_node->name; | |
86 | ||
b82b6cca | 87 | idle_state->flags = 0; |
9f14da34 LP |
88 | if (of_property_read_bool(state_node, "local-timer-stop")) |
89 | idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP; | |
90 | /* | |
91 | * TODO: | |
92 | * replace with kstrdup and pointer assignment when name | |
93 | * and desc become string pointers | |
94 | */ | |
95 | strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN - 1); | |
c00bc5df | 96 | strncpy(idle_state->desc, desc, CPUIDLE_DESC_LEN - 1); |
9f14da34 LP |
97 | return 0; |
98 | } | |
99 | ||
100 | /* | |
101 | * Check that the idle state is uniform across all CPUs in the CPUidle driver | |
102 | * cpumask | |
103 | */ | |
104 | static bool idle_state_valid(struct device_node *state_node, unsigned int idx, | |
105 | const cpumask_t *cpumask) | |
106 | { | |
107 | int cpu; | |
108 | struct device_node *cpu_node, *curr_state_node; | |
109 | bool valid = true; | |
110 | ||
111 | /* | |
112 | * Compare idle state phandles for index idx on all CPUs in the | |
113 | * CPUidle driver cpumask. Start from next logical cpu following | |
114 | * cpumask_first(cpumask) since that's the CPU state_node was | |
115 | * retrieved from. If a mismatch is found bail out straight | |
116 | * away since we certainly hit a firmware misconfiguration. | |
117 | */ | |
118 | for (cpu = cpumask_next(cpumask_first(cpumask), cpumask); | |
119 | cpu < nr_cpu_ids; cpu = cpumask_next(cpu, cpumask)) { | |
120 | cpu_node = of_cpu_device_node_get(cpu); | |
121 | curr_state_node = of_parse_phandle(cpu_node, "cpu-idle-states", | |
122 | idx); | |
123 | if (state_node != curr_state_node) | |
124 | valid = false; | |
125 | ||
126 | of_node_put(curr_state_node); | |
127 | of_node_put(cpu_node); | |
128 | if (!valid) | |
129 | break; | |
130 | } | |
131 | ||
132 | return valid; | |
133 | } | |
134 | ||
135 | /** | |
136 | * dt_init_idle_driver() - Parse the DT idle states and initialize the | |
137 | * idle driver states array | |
138 | * @drv: Pointer to CPU idle driver to be initialized | |
139 | * @matches: Array of of_device_id match structures to search in for | |
140 | * compatible idle state nodes. The data pointer for each valid | |
141 | * struct of_device_id entry in the matches array must point to | |
142 | * a function with the following signature, that corresponds to | |
143 | * the CPUidle state enter function signature: | |
144 | * | |
145 | * int (*)(struct cpuidle_device *dev, | |
146 | * struct cpuidle_driver *drv, | |
147 | * int index); | |
148 | * | |
149 | * @start_idx: First idle state index to be initialized | |
150 | * | |
151 | * If DT idle states are detected and are valid the state count and states | |
152 | * array entries in the cpuidle driver are initialized accordingly starting | |
153 | * from index start_idx. | |
154 | * | |
155 | * Return: number of valid DT idle states parsed, <0 on failure | |
156 | */ | |
157 | int dt_init_idle_driver(struct cpuidle_driver *drv, | |
158 | const struct of_device_id *matches, | |
159 | unsigned int start_idx) | |
160 | { | |
161 | struct cpuidle_state *idle_state; | |
162 | struct device_node *state_node, *cpu_node; | |
163 | int i, err = 0; | |
164 | const cpumask_t *cpumask; | |
165 | unsigned int state_idx = start_idx; | |
166 | ||
167 | if (state_idx >= CPUIDLE_STATE_MAX) | |
168 | return -EINVAL; | |
169 | /* | |
170 | * We get the idle states for the first logical cpu in the | |
171 | * driver mask (or cpu_possible_mask if the driver cpumask is not set) | |
172 | * and we check through idle_state_valid() if they are uniform | |
173 | * across CPUs, otherwise we hit a firmware misconfiguration. | |
174 | */ | |
175 | cpumask = drv->cpumask ? : cpu_possible_mask; | |
176 | cpu_node = of_cpu_device_node_get(cpumask_first(cpumask)); | |
177 | ||
178 | for (i = 0; ; i++) { | |
179 | state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i); | |
180 | if (!state_node) | |
181 | break; | |
182 | ||
b2cdd8e1 CJ |
183 | if (!of_device_is_available(state_node)) { |
184 | of_node_put(state_node); | |
97735da0 | 185 | continue; |
b2cdd8e1 | 186 | } |
97735da0 | 187 | |
9f14da34 | 188 | if (!idle_state_valid(state_node, i, cpumask)) { |
84dc4141 RH |
189 | pr_warn("%pOF idle state not valid, bailing out\n", |
190 | state_node); | |
9f14da34 LP |
191 | err = -EINVAL; |
192 | break; | |
193 | } | |
194 | ||
195 | if (state_idx == CPUIDLE_STATE_MAX) { | |
196 | pr_warn("State index reached static CPU idle driver states array size\n"); | |
197 | break; | |
198 | } | |
199 | ||
200 | idle_state = &drv->states[state_idx++]; | |
201 | err = init_state_node(idle_state, matches, state_node); | |
202 | if (err) { | |
84dc4141 RH |
203 | pr_err("Parsing idle state node %pOF failed with err %d\n", |
204 | state_node, err); | |
9f14da34 LP |
205 | err = -EINVAL; |
206 | break; | |
207 | } | |
208 | of_node_put(state_node); | |
209 | } | |
210 | ||
211 | of_node_put(state_node); | |
212 | of_node_put(cpu_node); | |
213 | if (err) | |
214 | return err; | |
215 | /* | |
216 | * Update the driver state count only if some valid DT idle states | |
217 | * were detected | |
218 | */ | |
219 | if (i) | |
220 | drv->state_count = state_idx; | |
221 | ||
222 | /* | |
223 | * Return the number of present and valid DT idle states, which can | |
224 | * also be 0 on platforms with missing DT idle states or legacy DT | |
225 | * configuration predating the DT idle states bindings. | |
226 | */ | |
227 | return i; | |
228 | } | |
229 | EXPORT_SYMBOL_GPL(dt_init_idle_driver); |