xref: /linux/drivers/char/ipmi/ipmi_dmi.c (revision 8b4483658364f05b2e32845c8f445cdfd9452286)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * A hack to create a platform device from a DMI entry.  This will
4  * allow autoloading of the IPMI drive based on SMBIOS entries.
5  */
6 
7 #define pr_fmt(fmt) "%s" fmt, "ipmi:dmi: "
8 #define dev_fmt pr_fmt
9 
10 #include <linux/ipmi.h>
11 #include <linux/init.h>
12 #include <linux/dmi.h>
13 #include <linux/platform_device.h>
14 #include <linux/property.h>
15 #include "ipmi_si_sm.h"
16 #include "ipmi_dmi.h"
17 #include "ipmi_plat_data.h"
18 
19 #define IPMI_DMI_TYPE_KCS	0x01
20 #define IPMI_DMI_TYPE_SMIC	0x02
21 #define IPMI_DMI_TYPE_BT	0x03
22 #define IPMI_DMI_TYPE_SSIF	0x04
23 
24 struct ipmi_dmi_info {
25 	enum si_type si_type;
26 	unsigned int space; /* addr space for si, intf# for ssif */
27 	unsigned long addr;
28 	u8 slave_addr;
29 	struct ipmi_dmi_info *next;
30 };
31 
32 static struct ipmi_dmi_info *ipmi_dmi_infos;
33 
34 static int ipmi_dmi_nr __initdata;
35 
36 static void __init dmi_add_platform_ipmi(unsigned long base_addr,
37 					 unsigned int space,
38 					 u8 slave_addr,
39 					 int irq,
40 					 int offset,
41 					 int type)
42 {
43 	const char *name;
44 	struct ipmi_dmi_info *info;
45 	struct ipmi_plat_data p;
46 
47 	memset(&p, 0, sizeof(p));
48 
49 	name = "dmi-ipmi-si";
50 	switch (type) {
51 	case IPMI_DMI_TYPE_SSIF:
52 		name = "dmi-ipmi-ssif";
53 		p.type = SI_TYPE_INVALID;
54 		break;
55 	case IPMI_DMI_TYPE_BT:
56 		p.type = SI_BT;
57 		break;
58 	case IPMI_DMI_TYPE_KCS:
59 		p.type = SI_KCS;
60 		break;
61 	case IPMI_DMI_TYPE_SMIC:
62 		p.type = SI_SMIC;
63 		break;
64 	default:
65 		pr_err("Invalid IPMI type: %d\n", type);
66 		return;
67 	}
68 
69 	p.addr = base_addr;
70 	p.space = space;
71 	p.regspacing = offset;
72 	p.irq = irq;
73 	p.slave_addr = slave_addr;
74 	p.addr_source = SI_SMBIOS;
75 
76 	info = kmalloc(sizeof(*info), GFP_KERNEL);
77 	if (!info) {
78 		pr_warn("Could not allocate dmi info\n");
79 	} else {
80 		info->si_type = p.type;
81 		info->space = space;
82 		info->addr = base_addr;
83 		info->slave_addr = slave_addr;
84 		info->next = ipmi_dmi_infos;
85 		ipmi_dmi_infos = info;
86 	}
87 
88 	if (ipmi_platform_add(name, ipmi_dmi_nr, &p))
89 		ipmi_dmi_nr++;
90 }
91 
92 /*
93  * Look up the slave address for a given interface.  This is here
94  * because ACPI doesn't have a slave address while SMBIOS does, but we
95  * prefer using ACPI so the ACPI code can use the IPMI namespace.
96  * This function allows an ACPI-specified IPMI device to look up the
97  * slave address from the DMI table.
98  */
99 int ipmi_dmi_get_slave_addr(enum si_type si_type, unsigned int space,
100 			    unsigned long base_addr)
101 {
102 	struct ipmi_dmi_info *info = ipmi_dmi_infos;
103 
104 	while (info) {
105 		if (info->si_type == si_type &&
106 		    info->space == space &&
107 		    info->addr == base_addr)
108 			return info->slave_addr;
109 		info = info->next;
110 	}
111 
112 	return 0;
113 }
114 EXPORT_SYMBOL(ipmi_dmi_get_slave_addr);
115 
116 #define DMI_IPMI_MIN_LENGTH	0x10
117 #define DMI_IPMI_VER2_LENGTH	0x12
118 #define DMI_IPMI_TYPE		4
119 #define DMI_IPMI_SLAVEADDR	6
120 #define DMI_IPMI_ADDR		8
121 #define DMI_IPMI_ACCESS		0x10
122 #define DMI_IPMI_IRQ		0x11
123 #define DMI_IPMI_IO_MASK	0xfffe
124 
125 static void __init dmi_decode_ipmi(const struct dmi_header *dm)
126 {
127 	const u8 *data = (const u8 *) dm;
128 	int space = IPMI_IO_ADDR_SPACE;
129 	unsigned long base_addr;
130 	u8 len = dm->length;
131 	u8 slave_addr;
132 	int irq = 0, offset = 0;
133 	int type;
134 
135 	if (len < DMI_IPMI_MIN_LENGTH)
136 		return;
137 
138 	type = data[DMI_IPMI_TYPE];
139 	slave_addr = data[DMI_IPMI_SLAVEADDR];
140 
141 	memcpy(&base_addr, data + DMI_IPMI_ADDR, sizeof(unsigned long));
142 	if (!base_addr) {
143 		pr_err("Base address is zero, assuming no IPMI interface\n");
144 		return;
145 	}
146 	if (len >= DMI_IPMI_VER2_LENGTH) {
147 		if (type == IPMI_DMI_TYPE_SSIF) {
148 			space = 0; /* Match I2C interface 0. */
149 			base_addr = data[DMI_IPMI_ADDR] >> 1;
150 			if (base_addr == 0) {
151 				/*
152 				 * Some broken systems put the I2C address in
153 				 * the slave address field.  We try to
154 				 * accommodate them here.
155 				 */
156 				base_addr = data[DMI_IPMI_SLAVEADDR] >> 1;
157 				slave_addr = 0;
158 			}
159 		} else {
160 			if (base_addr & 1) {
161 				/* I/O */
162 				base_addr &= DMI_IPMI_IO_MASK;
163 			} else {
164 				/* Memory */
165 				space = IPMI_MEM_ADDR_SPACE;
166 			}
167 
168 			/*
169 			 * If bit 4 of byte 0x10 is set, then the lsb
170 			 * for the address is odd.
171 			 */
172 			base_addr |= (data[DMI_IPMI_ACCESS] >> 4) & 1;
173 
174 			irq = data[DMI_IPMI_IRQ];
175 
176 			/*
177 			 * The top two bits of byte 0x10 hold the
178 			 * register spacing.
179 			 */
180 			switch ((data[DMI_IPMI_ACCESS] >> 6) & 3) {
181 			case 0: /* Byte boundaries */
182 				offset = 1;
183 				break;
184 			case 1: /* 32-bit boundaries */
185 				offset = 4;
186 				break;
187 			case 2: /* 16-byte boundaries */
188 				offset = 16;
189 				break;
190 			default:
191 				pr_err("Invalid offset: 0\n");
192 				return;
193 			}
194 		}
195 	} else {
196 		/* Old DMI spec. */
197 		/*
198 		 * Note that technically, the lower bit of the base
199 		 * address should be 1 if the address is I/O and 0 if
200 		 * the address is in memory.  So many systems get that
201 		 * wrong (and all that I have seen are I/O) so we just
202 		 * ignore that bit and assume I/O.  Systems that use
203 		 * memory should use the newer spec, anyway.
204 		 */
205 		base_addr = base_addr & DMI_IPMI_IO_MASK;
206 		offset = 1;
207 	}
208 
209 	dmi_add_platform_ipmi(base_addr, space, slave_addr, irq,
210 			      offset, type);
211 }
212 
213 static int __init scan_for_dmi_ipmi(void)
214 {
215 	const struct dmi_device *dev = NULL;
216 
217 	while ((dev = dmi_find_device(DMI_DEV_TYPE_IPMI, NULL, dev)))
218 		dmi_decode_ipmi((const struct dmi_header *) dev->device_data);
219 
220 	return 0;
221 }
222 subsys_initcall(scan_for_dmi_ipmi);
223