xref: /openbmc/linux/arch/arm/kernel/smp_scu.c (revision 2a598d0b)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/arch/arm/kernel/smp_scu.c
4  *
5  *  Copyright (C) 2002 ARM Ltd.
6  *  All Rights Reserved
7  */
8 #include <linux/init.h>
9 #include <linux/io.h>
10 
11 #include <asm/smp_plat.h>
12 #include <asm/smp_scu.h>
13 #include <asm/cacheflush.h>
14 #include <asm/cputype.h>
15 
16 #define SCU_CTRL		0x00
17 #define SCU_ENABLE		(1 << 0)
18 #define SCU_STANDBY_ENABLE	(1 << 5)
19 #define SCU_CONFIG		0x04
20 #define SCU_CPU_STATUS		0x08
21 #define SCU_CPU_STATUS_MASK	GENMASK(1, 0)
22 #define SCU_INVALIDATE		0x0c
23 #define SCU_FPGA_REVISION	0x10
24 
25 #ifdef CONFIG_SMP
26 /*
27  * Get the number of CPU cores from the SCU configuration
28  */
29 unsigned int __init scu_get_core_count(void __iomem *scu_base)
30 {
31 	unsigned int ncores = readl_relaxed(scu_base + SCU_CONFIG);
32 	return (ncores & 0x03) + 1;
33 }
34 
35 /*
36  * Enable the SCU
37  */
38 void scu_enable(void __iomem *scu_base)
39 {
40 	u32 scu_ctrl;
41 
42 #ifdef CONFIG_ARM_ERRATA_764369
43 	/* Cortex-A9 only */
44 	if ((read_cpuid_id() & 0xff0ffff0) == 0x410fc090) {
45 		scu_ctrl = readl_relaxed(scu_base + 0x30);
46 		if (!(scu_ctrl & 1))
47 			writel_relaxed(scu_ctrl | 0x1, scu_base + 0x30);
48 	}
49 #endif
50 
51 	scu_ctrl = readl_relaxed(scu_base + SCU_CTRL);
52 	/* already enabled? */
53 	if (scu_ctrl & SCU_ENABLE)
54 		return;
55 
56 	scu_ctrl |= SCU_ENABLE;
57 
58 	/* Cortex-A9 earlier than r2p0 has no standby bit in SCU */
59 	if ((read_cpuid_id() & 0xff0ffff0) == 0x410fc090 &&
60 	    (read_cpuid_id() & 0x00f0000f) >= 0x00200000)
61 		scu_ctrl |= SCU_STANDBY_ENABLE;
62 
63 	writel_relaxed(scu_ctrl, scu_base + SCU_CTRL);
64 
65 	/*
66 	 * Ensure that the data accessed by CPU0 before the SCU was
67 	 * initialised is visible to the other CPUs.
68 	 */
69 	flush_cache_all();
70 }
71 #endif
72 
73 static int scu_set_power_mode_internal(void __iomem *scu_base,
74 				       unsigned int logical_cpu,
75 				       unsigned int mode)
76 {
77 	unsigned int val;
78 	int cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(logical_cpu), 0);
79 
80 	if (mode > 3 || mode == 1 || cpu > 3)
81 		return -EINVAL;
82 
83 	val = readb_relaxed(scu_base + SCU_CPU_STATUS + cpu);
84 	val &= ~SCU_CPU_STATUS_MASK;
85 	val |= mode;
86 	writeb_relaxed(val, scu_base + SCU_CPU_STATUS + cpu);
87 
88 	return 0;
89 }
90 
91 /*
92  * Set the executing CPUs power mode as defined.  This will be in
93  * preparation for it executing a WFI instruction.
94  *
95  * This function must be called with preemption disabled, and as it
96  * has the side effect of disabling coherency, caches must have been
97  * flushed.  Interrupts must also have been disabled.
98  */
99 int scu_power_mode(void __iomem *scu_base, unsigned int mode)
100 {
101 	return scu_set_power_mode_internal(scu_base, smp_processor_id(), mode);
102 }
103 
104 /*
105  * Set the given (logical) CPU's power mode to SCU_PM_NORMAL.
106  */
107 int scu_cpu_power_enable(void __iomem *scu_base, unsigned int cpu)
108 {
109 	return scu_set_power_mode_internal(scu_base, cpu, SCU_PM_NORMAL);
110 }
111 
112 int scu_get_cpu_power_mode(void __iomem *scu_base, unsigned int logical_cpu)
113 {
114 	unsigned int val;
115 	int cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(logical_cpu), 0);
116 
117 	if (cpu > 3)
118 		return -EINVAL;
119 
120 	val = readb_relaxed(scu_base + SCU_CPU_STATUS + cpu);
121 	val &= SCU_CPU_STATUS_MASK;
122 
123 	return val;
124 }
125