1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * vSMPowered(tm) systems specific initialization
4 * Copyright (C) 2005 ScaleMP Inc.
5 *
6 * Ravikiran Thirumalai <kiran@scalemp.com>,
7 * Shai Fultheim <shai@scalemp.com>
8 * Paravirt ops integration: Glauber de Oliveira Costa <gcosta@redhat.com>,
9 *			     Ravikiran Thirumalai <kiran@scalemp.com>
10 */
11
12#include <linux/init.h>
13#include <linux/pci_ids.h>
14#include <linux/pci_regs.h>
15#include <linux/smp.h>
16#include <linux/irq.h>
17
18#include <asm/apic.h>
19#include <asm/pci-direct.h>
20#include <asm/io.h>
21#include <asm/paravirt.h>
22#include <asm/setup.h>
23
24#define TOPOLOGY_REGISTER_OFFSET 0x10
25
26#ifdef CONFIG_PCI
27static void __init set_vsmp_ctl(void)
28{
29	void __iomem *address;
30	unsigned int cap, ctl, cfg;
31
32	/* set vSMP magic bits to indicate vSMP capable kernel */
33	cfg = read_pci_config(0, 0x1f, 0, PCI_BASE_ADDRESS_0);
34	address = early_ioremap(cfg, 8);
35	cap = readl(address);
36	ctl = readl(address + 4);
37	printk(KERN_INFO "vSMP CTL: capabilities:0x%08x  control:0x%08x\n",
38	       cap, ctl);
39
40	/* If possible, let the vSMP foundation route the interrupt optimally */
41#ifdef CONFIG_SMP
42	if (cap & ctl & BIT(8)) {
43		ctl &= ~BIT(8);
44
45#ifdef CONFIG_PROC_FS
46		/* Don't let users change irq affinity via procfs */
47		no_irq_affinity = 1;
48#endif
49	}
50#endif
51
52	writel(ctl, address + 4);
53	ctl = readl(address + 4);
54	pr_info("vSMP CTL: control set to:0x%08x\n", ctl);
55
56	early_iounmap(address, 8);
57}
58static int is_vsmp = -1;
59
60static void __init detect_vsmp_box(void)
61{
62	is_vsmp = 0;
63
64	if (!early_pci_allowed())
65		return;
66
67	/* Check if we are running on a ScaleMP vSMPowered box */
68	if (read_pci_config(0, 0x1f, 0, PCI_VENDOR_ID) ==
69	     (PCI_VENDOR_ID_SCALEMP | (PCI_DEVICE_ID_SCALEMP_VSMP_CTL << 16)))
70		is_vsmp = 1;
71}
72
73static int is_vsmp_box(void)
74{
75	if (is_vsmp != -1)
76		return is_vsmp;
77	else {
78		WARN_ON_ONCE(1);
79		return 0;
80	}
81}
82
83#else
84static void __init detect_vsmp_box(void)
85{
86}
87static int is_vsmp_box(void)
88{
89	return 0;
90}
91static void __init set_vsmp_ctl(void)
92{
93}
94#endif
95
96static void __init vsmp_cap_cpus(void)
97{
98#if !defined(CONFIG_X86_VSMP) && defined(CONFIG_SMP) && defined(CONFIG_PCI)
99	void __iomem *address;
100	unsigned int cfg, topology, node_shift, maxcpus;
101
102	/*
103	 * CONFIG_X86_VSMP is not configured, so limit the number CPUs to the
104	 * ones present in the first board, unless explicitly overridden by
105	 * setup_max_cpus
106	 */
107	if (setup_max_cpus != NR_CPUS)
108		return;
109
110	/* Read the vSMP Foundation topology register */
111	cfg = read_pci_config(0, 0x1f, 0, PCI_BASE_ADDRESS_0);
112	address = early_ioremap(cfg + TOPOLOGY_REGISTER_OFFSET, 4);
113	if (WARN_ON(!address))
114		return;
115
116	topology = readl(address);
117	node_shift = (topology >> 16) & 0x7;
118	if (!node_shift)
119		/* The value 0 should be decoded as 8 */
120		node_shift = 8;
121	maxcpus = (topology & ((1 << node_shift) - 1)) + 1;
122
123	pr_info("vSMP CTL: Capping CPUs to %d (CONFIG_X86_VSMP is unset)\n",
124		maxcpus);
125	setup_max_cpus = maxcpus;
126	early_iounmap(address, 4);
127#endif
128}
129
130void __init vsmp_init(void)
131{
132	detect_vsmp_box();
133	if (!is_vsmp_box())
134		return;
135
136	vsmp_cap_cpus();
137
138	set_vsmp_ctl();
139	return;
140}
141