1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * DT idle states parsing code. |
4 | * |
5 | * Copyright (C) 2014 ARM Ltd. |
6 | * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> |
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 | |
18 | #include "dt_idle_states.h" |
19 | |
20 | static int init_state_node(struct cpuidle_state *idle_state, |
21 | const struct of_device_id *match_id, |
22 | struct device_node *state_node) |
23 | { |
24 | int err; |
25 | const char *desc; |
26 | |
27 | /* |
28 | * CPUidle drivers are expected to initialize the const void *data |
29 | * pointer of the passed in struct of_device_id array to the idle |
30 | * state enter function. |
31 | */ |
32 | idle_state->enter = match_id->data; |
33 | /* |
34 | * Since this is not a "coupled" state, it's safe to assume interrupts |
35 | * won't be enabled when it exits allowing the tick to be frozen |
36 | * safely. So enter() can be also enter_s2idle() callback. |
37 | */ |
38 | idle_state->enter_s2idle = match_id->data; |
39 | |
40 | err = of_property_read_u32(np: state_node, propname: "wakeup-latency-us" , |
41 | out_value: &idle_state->exit_latency); |
42 | if (err) { |
43 | u32 entry_latency, exit_latency; |
44 | |
45 | err = of_property_read_u32(np: state_node, propname: "entry-latency-us" , |
46 | out_value: &entry_latency); |
47 | if (err) { |
48 | pr_debug(" * %pOF missing entry-latency-us property\n" , |
49 | state_node); |
50 | return -EINVAL; |
51 | } |
52 | |
53 | err = of_property_read_u32(np: state_node, propname: "exit-latency-us" , |
54 | out_value: &exit_latency); |
55 | if (err) { |
56 | pr_debug(" * %pOF missing exit-latency-us property\n" , |
57 | state_node); |
58 | return -EINVAL; |
59 | } |
60 | /* |
61 | * If wakeup-latency-us is missing, default to entry+exit |
62 | * latencies as defined in idle states bindings |
63 | */ |
64 | idle_state->exit_latency = entry_latency + exit_latency; |
65 | } |
66 | |
67 | err = of_property_read_u32(np: state_node, propname: "min-residency-us" , |
68 | out_value: &idle_state->target_residency); |
69 | if (err) { |
70 | pr_debug(" * %pOF missing min-residency-us property\n" , |
71 | state_node); |
72 | return -EINVAL; |
73 | } |
74 | |
75 | err = of_property_read_string(np: state_node, propname: "idle-state-name" , out_string: &desc); |
76 | if (err) |
77 | desc = state_node->name; |
78 | |
79 | idle_state->flags = CPUIDLE_FLAG_RCU_IDLE; |
80 | if (of_property_read_bool(np: state_node, propname: "local-timer-stop" )) |
81 | idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP; |
82 | /* |
83 | * TODO: |
84 | * replace with kstrdup and pointer assignment when name |
85 | * and desc become string pointers |
86 | */ |
87 | strscpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN); |
88 | strscpy(idle_state->desc, desc, CPUIDLE_DESC_LEN); |
89 | return 0; |
90 | } |
91 | |
92 | /* |
93 | * Check that the idle state is uniform across all CPUs in the CPUidle driver |
94 | * cpumask |
95 | */ |
96 | static bool idle_state_valid(struct device_node *state_node, unsigned int idx, |
97 | const cpumask_t *cpumask) |
98 | { |
99 | int cpu; |
100 | struct device_node *cpu_node, *curr_state_node; |
101 | bool valid = true; |
102 | |
103 | /* |
104 | * Compare idle state phandles for index idx on all CPUs in the |
105 | * CPUidle driver cpumask. Start from next logical cpu following |
106 | * cpumask_first(cpumask) since that's the CPU state_node was |
107 | * retrieved from. If a mismatch is found bail out straight |
108 | * away since we certainly hit a firmware misconfiguration. |
109 | */ |
110 | for (cpu = cpumask_next(n: cpumask_first(srcp: cpumask), srcp: cpumask); |
111 | cpu < nr_cpu_ids; cpu = cpumask_next(n: cpu, srcp: cpumask)) { |
112 | cpu_node = of_cpu_device_node_get(cpu); |
113 | curr_state_node = of_get_cpu_state_node(cpu_node, index: idx); |
114 | if (state_node != curr_state_node) |
115 | valid = false; |
116 | |
117 | of_node_put(node: curr_state_node); |
118 | of_node_put(node: cpu_node); |
119 | if (!valid) |
120 | break; |
121 | } |
122 | |
123 | return valid; |
124 | } |
125 | |
126 | /** |
127 | * dt_init_idle_driver() - Parse the DT idle states and initialize the |
128 | * idle driver states array |
129 | * @drv: Pointer to CPU idle driver to be initialized |
130 | * @matches: Array of of_device_id match structures to search in for |
131 | * compatible idle state nodes. The data pointer for each valid |
132 | * struct of_device_id entry in the matches array must point to |
133 | * a function with the following signature, that corresponds to |
134 | * the CPUidle state enter function signature: |
135 | * |
136 | * int (*)(struct cpuidle_device *dev, |
137 | * struct cpuidle_driver *drv, |
138 | * int index); |
139 | * |
140 | * @start_idx: First idle state index to be initialized |
141 | * |
142 | * If DT idle states are detected and are valid the state count and states |
143 | * array entries in the cpuidle driver are initialized accordingly starting |
144 | * from index start_idx. |
145 | * |
146 | * Return: number of valid DT idle states parsed, <0 on failure |
147 | */ |
148 | int dt_init_idle_driver(struct cpuidle_driver *drv, |
149 | const struct of_device_id *matches, |
150 | unsigned int start_idx) |
151 | { |
152 | struct cpuidle_state *idle_state; |
153 | struct device_node *state_node, *cpu_node; |
154 | const struct of_device_id *match_id; |
155 | int i, err = 0; |
156 | const cpumask_t *cpumask; |
157 | unsigned int state_idx = start_idx; |
158 | |
159 | if (state_idx >= CPUIDLE_STATE_MAX) |
160 | return -EINVAL; |
161 | /* |
162 | * We get the idle states for the first logical cpu in the |
163 | * driver mask (or cpu_possible_mask if the driver cpumask is not set) |
164 | * and we check through idle_state_valid() if they are uniform |
165 | * across CPUs, otherwise we hit a firmware misconfiguration. |
166 | */ |
167 | cpumask = drv->cpumask ? : cpu_possible_mask; |
168 | cpu_node = of_cpu_device_node_get(cpu: cpumask_first(srcp: cpumask)); |
169 | |
170 | for (i = 0; ; i++) { |
171 | state_node = of_get_cpu_state_node(cpu_node, index: i); |
172 | if (!state_node) |
173 | break; |
174 | |
175 | match_id = of_match_node(matches, node: state_node); |
176 | if (!match_id) { |
177 | err = -ENODEV; |
178 | break; |
179 | } |
180 | |
181 | if (!of_device_is_available(device: state_node)) { |
182 | of_node_put(node: state_node); |
183 | continue; |
184 | } |
185 | |
186 | if (!idle_state_valid(state_node, idx: i, cpumask)) { |
187 | pr_warn("%pOF idle state not valid, bailing out\n" , |
188 | state_node); |
189 | err = -EINVAL; |
190 | break; |
191 | } |
192 | |
193 | if (state_idx == CPUIDLE_STATE_MAX) { |
194 | pr_warn("State index reached static CPU idle driver states array size\n" ); |
195 | break; |
196 | } |
197 | |
198 | idle_state = &drv->states[state_idx++]; |
199 | err = init_state_node(idle_state, match_id, state_node); |
200 | if (err) { |
201 | pr_err("Parsing idle state node %pOF failed with err %d\n" , |
202 | state_node, err); |
203 | err = -EINVAL; |
204 | break; |
205 | } |
206 | of_node_put(node: state_node); |
207 | } |
208 | |
209 | of_node_put(node: state_node); |
210 | of_node_put(node: cpu_node); |
211 | if (err) |
212 | return err; |
213 | |
214 | /* Set the number of total supported idle states. */ |
215 | drv->state_count = state_idx; |
216 | |
217 | /* |
218 | * Return the number of present and valid DT idle states, which can |
219 | * also be 0 on platforms with missing DT idle states or legacy DT |
220 | * configuration predating the DT idle states bindings. |
221 | */ |
222 | return state_idx - start_idx; |
223 | } |
224 | EXPORT_SYMBOL_GPL(dt_init_idle_driver); |
225 | |