1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
|
/*
* DT idle states parsing code.
*
* Copyright (C) 2014 ARM Ltd.
* Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#define pr_fmt(fmt) "DT idle-states: " fmt
#include <linux/cpuidle.h>
#include <linux/cpumask.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include "dt_idle_states.h"
static int init_state_node(struct cpuidle_state *idle_state,
const struct of_device_id *matches,
struct device_node *state_node)
{
int err;
const struct of_device_id *match_id;
const char *desc;
match_id = of_match_node(matches, state_node);
if (!match_id)
return -ENODEV;
/*
* CPUidle drivers are expected to initialize the const void *data
* pointer of the passed in struct of_device_id array to the idle
* state enter function.
*/
idle_state->enter = match_id->data;
/*
* Since this is not a "coupled" state, it's safe to assume interrupts
* won't be enabled when it exits allowing the tick to be frozen
* safely. So enter() can be also enter_freeze() callback.
*/
idle_state->enter_freeze = match_id->data;
err = of_property_read_u32(state_node, "wakeup-latency-us",
&idle_state->exit_latency);
if (err) {
u32 entry_latency, exit_latency;
err = of_property_read_u32(state_node, "entry-latency-us",
&entry_latency);
if (err) {
pr_debug(" * %s missing entry-latency-us property\n",
state_node->full_name);
return -EINVAL;
}
err = of_property_read_u32(state_node, "exit-latency-us",
&exit_latency);
if (err) {
pr_debug(" * %s missing exit-latency-us property\n",
state_node->full_name);
return -EINVAL;
}
/*
* If wakeup-latency-us is missing, default to entry+exit
* latencies as defined in idle states bindings
*/
idle_state->exit_latency = entry_latency + exit_latency;
}
err = of_property_read_u32(state_node, "min-residency-us",
&idle_state->target_residency);
if (err) {
pr_debug(" * %s missing min-residency-us property\n",
state_node->full_name);
return -EINVAL;
}
err = of_property_read_string(state_node, "idle-state-name", &desc);
if (err)
desc = state_node->name;
idle_state->flags = 0;
if (of_property_read_bool(state_node, "local-timer-stop"))
idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP;
/*
* TODO:
* replace with kstrdup and pointer assignment when name
* and desc become string pointers
*/
strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN - 1);
strncpy(idle_state->desc, desc, CPUIDLE_DESC_LEN - 1);
return 0;
}
/*
* Check that the idle state is uniform across all CPUs in the CPUidle driver
* cpumask
*/
static bool idle_state_valid(struct device_node *state_node, unsigned int idx,
const cpumask_t *cpumask)
{
int cpu;
struct device_node *cpu_node, *curr_state_node;
bool valid = true;
/*
* Compare idle state phandles for index idx on all CPUs in the
* CPUidle driver cpumask. Start from next logical cpu following
* cpumask_first(cpumask) since that's the CPU state_node was
* retrieved from. If a mismatch is found bail out straight
* away since we certainly hit a firmware misconfiguration.
*/
for (cpu = cpumask_next(cpumask_first(cpumask), cpumask);
cpu < nr_cpu_ids; cpu = cpumask_next(cpu, cpumask)) {
cpu_node = of_cpu_device_node_get(cpu);
curr_state_node = of_parse_phandle(cpu_node, "cpu-idle-states",
idx);
if (state_node != curr_state_node)
valid = false;
of_node_put(curr_state_node);
of_node_put(cpu_node);
if (!valid)
break;
}
return valid;
}
/**
* dt_init_idle_driver() - Parse the DT idle states and initialize the
* idle driver states array
* @drv: Pointer to CPU idle driver to be initialized
* @matches: Array of of_device_id match structures to search in for
* compatible idle state nodes. The data pointer for each valid
* struct of_device_id entry in the matches array must point to
* a function with the following signature, that corresponds to
* the CPUidle state enter function signature:
*
* int (*)(struct cpuidle_device *dev,
* struct cpuidle_driver *drv,
* int index);
*
* @start_idx: First idle state index to be initialized
*
* If DT idle states are detected and are valid the state count and states
* array entries in the cpuidle driver are initialized accordingly starting
* from index start_idx.
*
* Return: number of valid DT idle states parsed, <0 on failure
*/
int dt_init_idle_driver(struct cpuidle_driver *drv,
const struct of_device_id *matches,
unsigned int start_idx)
{
struct cpuidle_state *idle_state;
struct device_node *state_node, *cpu_node;
int i, err = 0;
const cpumask_t *cpumask;
unsigned int state_idx = start_idx;
if (state_idx >= CPUIDLE_STATE_MAX)
return -EINVAL;
/*
* We get the idle states for the first logical cpu in the
* driver mask (or cpu_possible_mask if the driver cpumask is not set)
* and we check through idle_state_valid() if they are uniform
* across CPUs, otherwise we hit a firmware misconfiguration.
*/
cpumask = drv->cpumask ? : cpu_possible_mask;
cpu_node = of_cpu_device_node_get(cpumask_first(cpumask));
for (i = 0; ; i++) {
state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i);
if (!state_node)
break;
if (!of_device_is_available(state_node)) {
of_node_put(state_node);
continue;
}
if (!idle_state_valid(state_node, i, cpumask)) {
pr_warn("%s idle state not valid, bailing out\n",
state_node->full_name);
err = -EINVAL;
break;
}
if (state_idx == CPUIDLE_STATE_MAX) {
pr_warn("State index reached static CPU idle driver states array size\n");
break;
}
idle_state = &drv->states[state_idx++];
err = init_state_node(idle_state, matches, state_node);
if (err) {
pr_err("Parsing idle state node %s failed with err %d\n",
state_node->full_name, err);
err = -EINVAL;
break;
}
of_node_put(state_node);
}
of_node_put(state_node);
of_node_put(cpu_node);
if (err)
return err;
/*
* Update the driver state count only if some valid DT idle states
* were detected
*/
if (i)
drv->state_count = state_idx;
/*
* Return the number of present and valid DT idle states, which can
* also be 0 on platforms with missing DT idle states or legacy DT
* configuration predating the DT idle states bindings.
*/
return i;
}
EXPORT_SYMBOL_GPL(dt_init_idle_driver);
|
