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 		.name			= "C1",
69 		.desc			= "ARM little-cluster power down",
70 	},
71 	.state_count = 2,
72 };
73 
74 static const struct of_device_id bl_idle_state_match[] __initconst = {
75 	{ .compatible = "arm,idle-state",
76 	  .data = bl_enter_powerdown },
77 	{ },
78 };
79 
80 static struct cpuidle_driver bl_idle_big_driver = {
81 	.name = "big_idle",
82 	.owner = THIS_MODULE,
83 	.states[0] = ARM_CPUIDLE_WFI_STATE,
84 	.states[1] = {
85 		.enter			= bl_enter_powerdown,
86 		.exit_latency		= 500,
87 		.target_residency	= 2000,
88 		.flags			= CPUIDLE_FLAG_TIMER_STOP,
89 		.name			= "C1",
90 		.desc			= "ARM big-cluster power down",
91 	},
92 	.state_count = 2,
93 };
94 
95 /*
96  * notrace prevents trace shims from getting inserted where they
97  * should not. Global jumps and ldrex/strex must not be inserted
98  * in power down sequences where caches and MMU may be turned off.
99  */
100 static int notrace bl_powerdown_finisher(unsigned long arg)
101 {
102 	/* MCPM works with HW CPU identifiers */
103 	unsigned int mpidr = read_cpuid_mpidr();
104 	unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
105 	unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
106 
107 	mcpm_set_entry_vector(cpu, cluster, cpu_resume);
108 	mcpm_cpu_suspend();
109 
110 	/* return value != 0 means failure */
111 	return 1;
112 }
113 
114 /**
115  * bl_enter_powerdown - Programs CPU to enter the specified state
116  * @dev: cpuidle device
117  * @drv: The target state to be programmed
118  * @idx: state index
119  *
120  * Called from the CPUidle framework to program the device to the
121  * specified target state selected by the governor.
122  */
123 static int bl_enter_powerdown(struct cpuidle_device *dev,
124 				struct cpuidle_driver *drv, int idx)
125 {
126 	cpu_pm_enter();
127 
128 	cpu_suspend(0, bl_powerdown_finisher);
129 
130 	/* signals the MCPM core that CPU is out of low power state */
131 	mcpm_cpu_powered_up();
132 
133 	cpu_pm_exit();
134 
135 	return idx;
136 }
137 
138 static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int part_id)
139 {
140 	struct cpumask *cpumask;
141 	int cpu;
142 
143 	cpumask = kzalloc(cpumask_size(), GFP_KERNEL);
144 	if (!cpumask)
145 		return -ENOMEM;
146 
147 	for_each_possible_cpu(cpu)
148 		if (smp_cpuid_part(cpu) == part_id)
149 			cpumask_set_cpu(cpu, cpumask);
150 
151 	drv->cpumask = cpumask;
152 
153 	return 0;
154 }
155 
156 static const struct of_device_id compatible_machine_match[] = {
157 	{ .compatible = "arm,vexpress,v2p-ca15_a7" },
158 	{ .compatible = "samsung,exynos5420" },
159 	{ .compatible = "samsung,exynos5800" },
160 	{},
161 };
162 
163 static int __init bl_idle_init(void)
164 {
165 	int ret;
166 	struct device_node *root = of_find_node_by_path("/");
167 	const struct of_device_id *match_id;
168 
169 	if (!root)
170 		return -ENODEV;
171 
172 	/*
173 	 * Initialize the driver just for a compliant set of machines
174 	 */
175 	match_id = of_match_node(compatible_machine_match, root);
176 
177 	of_node_put(root);
178 
179 	if (!match_id)
180 		return -ENODEV;
181 
182 	if (!mcpm_is_available())
183 		return -EUNATCH;
184 
185 	/*
186 	 * For now the differentiation between little and big cores
187 	 * is based on the part number. A7 cores are considered little
188 	 * cores, A15 are considered big cores. This distinction may
189 	 * evolve in the future with a more generic matching approach.
190 	 */
191 	ret = bl_idle_driver_init(&bl_idle_little_driver,
192 				  ARM_CPU_PART_CORTEX_A7);
193 	if (ret)
194 		return ret;
195 
196 	ret = bl_idle_driver_init(&bl_idle_big_driver, ARM_CPU_PART_CORTEX_A15);
197 	if (ret)
198 		goto out_uninit_little;
199 
200 	/* Start at index 1, index 0 standard WFI */
201 	ret = dt_init_idle_driver(&bl_idle_big_driver, bl_idle_state_match, 1);
202 	if (ret < 0)
203 		goto out_uninit_big;
204 
205 	/* Start at index 1, index 0 standard WFI */
206 	ret = dt_init_idle_driver(&bl_idle_little_driver,
207 				  bl_idle_state_match, 1);
208 	if (ret < 0)
209 		goto out_uninit_big;
210 
211 	ret = cpuidle_register(&bl_idle_little_driver, NULL);
212 	if (ret)
213 		goto out_uninit_big;
214 
215 	ret = cpuidle_register(&bl_idle_big_driver, NULL);
216 	if (ret)
217 		goto out_unregister_little;
218 
219 	return 0;
220 
221 out_unregister_little:
222 	cpuidle_unregister(&bl_idle_little_driver);
223 out_uninit_big:
224 	kfree(bl_idle_big_driver.cpumask);
225 out_uninit_little:
226 	kfree(bl_idle_little_driver.cpumask);
227 
228 	return ret;
229 }
230 device_initcall(bl_idle_init);
231