1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (c) 2013 ARM/Linaro
4  *
5  * Authors: Daniel Lezcano <daniel.lezcano@linaro.org>
6  *          Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
7  *          Nicolas Pitre <nicolas.pitre@linaro.org>
8  *
9  * Maintainer: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
10  * Maintainer: Daniel Lezcano <daniel.lezcano@linaro.org>
11  */
12 #include <linux/cpuidle.h>
13 #include <linux/cpu_pm.h>
14 #include <linux/slab.h>
15 #include <linux/of.h>
16 
17 #include <asm/cpu.h>
18 #include <asm/cputype.h>
19 #include <asm/cpuidle.h>
20 #include <asm/mcpm.h>
21 #include <asm/smp_plat.h>
22 #include <asm/suspend.h>
23 
24 #include "dt_idle_states.h"
25 
26 static int bl_enter_powerdown(struct cpuidle_device *dev,
27 			      struct cpuidle_driver *drv, int idx);
28 
29 /*
30  * NB: Owing to current menu governor behaviour big and LITTLE
31  * index 1 states have to define exit_latency and target_residency for
32  * cluster state since, when all CPUs in a cluster hit it, the cluster
33  * can be shutdown. This means that when a single CPU enters this state
34  * the exit_latency and target_residency values are somewhat overkill.
35  * There is no notion of cluster states in the menu governor, so CPUs
36  * have to define CPU states where possibly the cluster will be shutdown
37  * depending on the state of other CPUs. idle states entry and exit happen
38  * at random times; however the cluster state provides target_residency
39  * values as if all CPUs in a cluster enter the state at once; this is
40  * somewhat optimistic and behaviour should be fixed either in the governor
41  * or in the MCPM back-ends.
42  * To make this driver 100% generic the number of states and the exit_latency
43  * target_residency values must be obtained from device tree bindings.
44  *
45  * exit_latency: refers to the TC2 vexpress test chip and depends on the
46  * current cluster operating point. It is the time it takes to get the CPU
47  * up and running when the CPU is powered up on cluster wake-up from shutdown.
48  * Current values for big and LITTLE clusters are provided for clusters
49  * running at default operating points.
50  *
51  * target_residency: it is the minimum amount of time the cluster has
52  * to be down to break even in terms of power consumption. cluster
53  * shutdown has inherent dynamic power costs (L2 writebacks to DRAM
54  * being the main factor) that depend on the current operating points.
55  * The current values for both clusters are provided for a CPU whose half
56  * of L2 lines are dirty and require cleaning to DRAM, and takes into
57  * account leakage static power values related to the vexpress TC2 testchip.
58  */
59 static struct cpuidle_driver bl_idle_little_driver = {
60 	.name = "little_idle",
61 	.owner = THIS_MODULE,
62 	.states[0] = ARM_CPUIDLE_WFI_STATE,
63 	.states[1] = {
64 		.enter			= bl_enter_powerdown,
65 		.exit_latency		= 700,
66 		.target_residency	= 2500,
67 		.flags			= CPUIDLE_FLAG_TIMER_STOP |
68 					  CPUIDLE_FLAG_RCU_IDLE,
69 		.name			= "C1",
70 		.desc			= "ARM little-cluster power down",
71 	},
72 	.state_count = 2,
73 };
74 
75 static const struct of_device_id bl_idle_state_match[] __initconst = {
76 	{ .compatible = "arm,idle-state",
77 	  .data = bl_enter_powerdown },
78 	{ },
79 };
80 
81 static struct cpuidle_driver bl_idle_big_driver = {
82 	.name = "big_idle",
83 	.owner = THIS_MODULE,
84 	.states[0] = ARM_CPUIDLE_WFI_STATE,
85 	.states[1] = {
86 		.enter			= bl_enter_powerdown,
87 		.exit_latency		= 500,
88 		.target_residency	= 2000,
89 		.flags			= CPUIDLE_FLAG_TIMER_STOP |
90 					  CPUIDLE_FLAG_RCU_IDLE,
91 		.name			= "C1",
92 		.desc			= "ARM big-cluster power down",
93 	},
94 	.state_count = 2,
95 };
96 
97 /*
98  * notrace prevents trace shims from getting inserted where they
99  * should not. Global jumps and ldrex/strex must not be inserted
100  * in power down sequences where caches and MMU may be turned off.
101  */
102 static int notrace bl_powerdown_finisher(unsigned long arg)
103 {
104 	/* MCPM works with HW CPU identifiers */
105 	unsigned int mpidr = read_cpuid_mpidr();
106 	unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
107 	unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
108 
109 	mcpm_set_entry_vector(cpu, cluster, cpu_resume);
110 	mcpm_cpu_suspend();
111 
112 	/* return value != 0 means failure */
113 	return 1;
114 }
115 
116 /**
117  * bl_enter_powerdown - Programs CPU to enter the specified state
118  * @dev: cpuidle device
119  * @drv: The target state to be programmed
120  * @idx: state index
121  *
122  * Called from the CPUidle framework to program the device to the
123  * specified target state selected by the governor.
124  */
125 static __cpuidle int bl_enter_powerdown(struct cpuidle_device *dev,
126 					struct cpuidle_driver *drv, int idx)
127 {
128 	cpu_pm_enter();
129 	ct_cpuidle_enter();
130 
131 	cpu_suspend(0, bl_powerdown_finisher);
132 
133 	/* signals the MCPM core that CPU is out of low power state */
134 	mcpm_cpu_powered_up();
135 	ct_cpuidle_exit();
136 
137 	cpu_pm_exit();
138 
139 	return idx;
140 }
141 
142 static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int part_id)
143 {
144 	struct cpumask *cpumask;
145 	int cpu;
146 
147 	cpumask = kzalloc(cpumask_size(), GFP_KERNEL);
148 	if (!cpumask)
149 		return -ENOMEM;
150 
151 	for_each_possible_cpu(cpu)
152 		if (smp_cpuid_part(cpu) == part_id)
153 			cpumask_set_cpu(cpu, cpumask);
154 
155 	drv->cpumask = cpumask;
156 
157 	return 0;
158 }
159 
160 static const struct of_device_id compatible_machine_match[] = {
161 	{ .compatible = "arm,vexpress,v2p-ca15_a7" },
162 	{ .compatible = "google,peach" },
163 	{},
164 };
165 
166 static int __init bl_idle_init(void)
167 {
168 	int ret;
169 	struct device_node *root = of_find_node_by_path("/");
170 	const struct of_device_id *match_id;
171 
172 	if (!root)
173 		return -ENODEV;
174 
175 	/*
176 	 * Initialize the driver just for a compliant set of machines
177 	 */
178 	match_id = of_match_node(compatible_machine_match, root);
179 
180 	of_node_put(root);
181 
182 	if (!match_id)
183 		return -ENODEV;
184 
185 	if (!mcpm_is_available())
186 		return -EUNATCH;
187 
188 	/*
189 	 * For now the differentiation between little and big cores
190 	 * is based on the part number. A7 cores are considered little
191 	 * cores, A15 are considered big cores. This distinction may
192 	 * evolve in the future with a more generic matching approach.
193 	 */
194 	ret = bl_idle_driver_init(&bl_idle_little_driver,
195 				  ARM_CPU_PART_CORTEX_A7);
196 	if (ret)
197 		return ret;
198 
199 	ret = bl_idle_driver_init(&bl_idle_big_driver, ARM_CPU_PART_CORTEX_A15);
200 	if (ret)
201 		goto out_uninit_little;
202 
203 	/* Start at index 1, index 0 standard WFI */
204 	ret = dt_init_idle_driver(&bl_idle_big_driver, bl_idle_state_match, 1);
205 	if (ret < 0)
206 		goto out_uninit_big;
207 
208 	/* Start at index 1, index 0 standard WFI */
209 	ret = dt_init_idle_driver(&bl_idle_little_driver,
210 				  bl_idle_state_match, 1);
211 	if (ret < 0)
212 		goto out_uninit_big;
213 
214 	ret = cpuidle_register(&bl_idle_little_driver, NULL);
215 	if (ret)
216 		goto out_uninit_big;
217 
218 	ret = cpuidle_register(&bl_idle_big_driver, NULL);
219 	if (ret)
220 		goto out_unregister_little;
221 
222 	return 0;
223 
224 out_unregister_little:
225 	cpuidle_unregister(&bl_idle_little_driver);
226 out_uninit_big:
227 	kfree(bl_idle_big_driver.cpumask);
228 out_uninit_little:
229 	kfree(bl_idle_little_driver.cpumask);
230 
231 	return ret;
232 }
233 device_initcall(bl_idle_init);
234