xref: /openbmc/linux/arch/mips/kernel/mips-cpc.c (revision 4107fa70)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Copyright (C) 2013 Imagination Technologies
4  * Author: Paul Burton <paul.burton@mips.com>
5  */
6 
7 #include <linux/bitfield.h>
8 #include <linux/errno.h>
9 #include <linux/percpu.h>
10 #include <linux/of.h>
11 #include <linux/of_address.h>
12 #include <linux/spinlock.h>
13 
14 #include <asm/mips-cps.h>
15 
16 void __iomem *mips_cpc_base;
17 
18 static DEFINE_PER_CPU_ALIGNED(spinlock_t, cpc_core_lock);
19 
20 static DEFINE_PER_CPU_ALIGNED(unsigned long, cpc_core_lock_flags);
21 
mips_cpc_default_phys_base(void)22 phys_addr_t __weak mips_cpc_default_phys_base(void)
23 {
24 	struct device_node *cpc_node;
25 	struct resource res;
26 	int err;
27 
28 	cpc_node = of_find_compatible_node(of_root, NULL, "mti,mips-cpc");
29 	if (cpc_node) {
30 		err = of_address_to_resource(cpc_node, 0, &res);
31 		of_node_put(cpc_node);
32 		if (!err)
33 			return res.start;
34 	}
35 
36 	return 0;
37 }
38 
39 /**
40  * mips_cpc_phys_base - retrieve the physical base address of the CPC
41  *
42  * This function returns the physical base address of the Cluster Power
43  * Controller memory mapped registers, or 0 if no Cluster Power Controller
44  * is present.
45  */
mips_cpc_phys_base(void)46 static phys_addr_t mips_cpc_phys_base(void)
47 {
48 	unsigned long cpc_base;
49 
50 	if (!mips_cm_present())
51 		return 0;
52 
53 	if (!(read_gcr_cpc_status() & CM_GCR_CPC_STATUS_EX))
54 		return 0;
55 
56 	/* If the CPC is already enabled, leave it so */
57 	cpc_base = read_gcr_cpc_base();
58 	if (cpc_base & CM_GCR_CPC_BASE_CPCEN)
59 		return cpc_base & CM_GCR_CPC_BASE_CPCBASE;
60 
61 	/* Otherwise, use the default address */
62 	cpc_base = mips_cpc_default_phys_base();
63 	if (!cpc_base)
64 		return cpc_base;
65 
66 	/* Enable the CPC, mapped at the default address */
67 	write_gcr_cpc_base(cpc_base | CM_GCR_CPC_BASE_CPCEN);
68 	return cpc_base;
69 }
70 
mips_cpc_probe(void)71 int mips_cpc_probe(void)
72 {
73 	phys_addr_t addr;
74 	unsigned int cpu;
75 
76 	for_each_possible_cpu(cpu)
77 		spin_lock_init(&per_cpu(cpc_core_lock, cpu));
78 
79 	addr = mips_cpc_phys_base();
80 	if (!addr)
81 		return -ENODEV;
82 
83 	mips_cpc_base = ioremap(addr, 0x8000);
84 	if (!mips_cpc_base)
85 		return -ENXIO;
86 
87 	return 0;
88 }
89 
mips_cpc_lock_other(unsigned int core)90 void mips_cpc_lock_other(unsigned int core)
91 {
92 	unsigned int curr_core;
93 
94 	if (mips_cm_revision() >= CM_REV_CM3)
95 		/* Systems with CM >= 3 lock the CPC via mips_cm_lock_other */
96 		return;
97 
98 	preempt_disable();
99 	curr_core = cpu_core(&current_cpu_data);
100 	spin_lock_irqsave(&per_cpu(cpc_core_lock, curr_core),
101 			  per_cpu(cpc_core_lock_flags, curr_core));
102 	write_cpc_cl_other(FIELD_PREP(CPC_Cx_OTHER_CORENUM, core));
103 
104 	/*
105 	 * Ensure the core-other region reflects the appropriate core &
106 	 * VP before any accesses to it occur.
107 	 */
108 	mb();
109 }
110 
mips_cpc_unlock_other(void)111 void mips_cpc_unlock_other(void)
112 {
113 	unsigned int curr_core;
114 
115 	if (mips_cm_revision() >= CM_REV_CM3)
116 		/* Systems with CM >= 3 lock the CPC via mips_cm_lock_other */
117 		return;
118 
119 	curr_core = cpu_core(&current_cpu_data);
120 	spin_unlock_irqrestore(&per_cpu(cpc_core_lock, curr_core),
121 			       per_cpu(cpc_core_lock_flags, curr_core));
122 	preempt_enable();
123 }
124