1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Copyright (c) 2012 Linaro : Daniel Lezcano <daniel.lezcano@linaro.org> (IBM) |
4 | * |
5 | * Based on the work of Rickard Andersson <rickard.andersson@stericsson.com> |
6 | * and Jonas Aaberg <jonas.aberg@stericsson.com>. |
7 | */ |
8 | |
9 | #include <linux/init.h> |
10 | #include <linux/cpuidle.h> |
11 | #include <linux/spinlock.h> |
12 | #include <linux/atomic.h> |
13 | #include <linux/smp.h> |
14 | #include <linux/mfd/dbx500-prcmu.h> |
15 | #include <linux/platform_data/arm-ux500-pm.h> |
16 | #include <linux/platform_device.h> |
17 | |
18 | #include <asm/cpuidle.h> |
19 | |
20 | static atomic_t master = ATOMIC_INIT(0); |
21 | static DEFINE_SPINLOCK(master_lock); |
22 | |
23 | static inline int ux500_enter_idle(struct cpuidle_device *dev, |
24 | struct cpuidle_driver *drv, int index) |
25 | { |
26 | int this_cpu = smp_processor_id(); |
27 | bool recouple = false; |
28 | |
29 | if (atomic_inc_return(v: &master) == num_online_cpus()) { |
30 | |
31 | /* With this lock, we prevent the other cpu to exit and enter |
32 | * this function again and become the master */ |
33 | if (!spin_trylock(lock: &master_lock)) |
34 | goto wfi; |
35 | |
36 | /* decouple the gic from the A9 cores */ |
37 | if (prcmu_gic_decouple()) { |
38 | spin_unlock(lock: &master_lock); |
39 | goto out; |
40 | } |
41 | |
42 | /* If an error occur, we will have to recouple the gic |
43 | * manually */ |
44 | recouple = true; |
45 | |
46 | /* At this state, as the gic is decoupled, if the other |
47 | * cpu is in WFI, we have the guarantee it won't be wake |
48 | * up, so we can safely go to retention */ |
49 | if (!prcmu_is_cpu_in_wfi(cpu: this_cpu ? 0 : 1)) |
50 | goto out; |
51 | |
52 | /* The prcmu will be in charge of watching the interrupts |
53 | * and wake up the cpus */ |
54 | if (prcmu_copy_gic_settings()) |
55 | goto out; |
56 | |
57 | /* Check in the meantime an interrupt did |
58 | * not occur on the gic ... */ |
59 | if (prcmu_gic_pending_irq()) |
60 | goto out; |
61 | |
62 | /* ... and the prcmu */ |
63 | if (prcmu_pending_irq()) |
64 | goto out; |
65 | |
66 | /* Go to the retention state, the prcmu will wait for the |
67 | * cpu to go WFI and this is what happens after exiting this |
68 | * 'master' critical section */ |
69 | if (prcmu_set_power_state(state: PRCMU_AP_IDLE, keep_ulp_clk: true, keep_ap_pll: true)) |
70 | goto out; |
71 | |
72 | /* When we switch to retention, the prcmu is in charge |
73 | * of recoupling the gic automatically */ |
74 | recouple = false; |
75 | |
76 | spin_unlock(lock: &master_lock); |
77 | } |
78 | wfi: |
79 | cpu_do_idle(); |
80 | out: |
81 | atomic_dec(v: &master); |
82 | |
83 | if (recouple) { |
84 | prcmu_gic_recouple(); |
85 | spin_unlock(lock: &master_lock); |
86 | } |
87 | |
88 | return index; |
89 | } |
90 | |
91 | static struct cpuidle_driver ux500_idle_driver = { |
92 | .name = "ux500_idle" , |
93 | .owner = THIS_MODULE, |
94 | .states = { |
95 | ARM_CPUIDLE_WFI_STATE, |
96 | { |
97 | .enter = ux500_enter_idle, |
98 | .exit_latency = 70, |
99 | .target_residency = 260, |
100 | .flags = CPUIDLE_FLAG_TIMER_STOP, |
101 | .name = "ApIdle" , |
102 | .desc = "ARM Retention" , |
103 | }, |
104 | }, |
105 | .safe_state_index = 0, |
106 | .state_count = 2, |
107 | }; |
108 | |
109 | static int dbx500_cpuidle_probe(struct platform_device *pdev) |
110 | { |
111 | /* Configure wake up reasons */ |
112 | prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) | |
113 | PRCMU_WAKEUP(ABB)); |
114 | |
115 | return cpuidle_register(drv: &ux500_idle_driver, NULL); |
116 | } |
117 | |
118 | static struct platform_driver dbx500_cpuidle_plat_driver = { |
119 | .driver = { |
120 | .name = "db8500-cpuidle" , |
121 | }, |
122 | .probe = dbx500_cpuidle_probe, |
123 | }; |
124 | builtin_platform_driver(dbx500_cpuidle_plat_driver); |
125 | |