xref: /openbmc/linux/drivers/char/ipmi/ipmi_dmi.c (revision 104fb25f)
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_dmi.h"
16 #include "ipmi_plat_data.h"
17 
18 #define IPMI_DMI_TYPE_KCS	0x01
19 #define IPMI_DMI_TYPE_SMIC	0x02
20 #define IPMI_DMI_TYPE_BT	0x03
21 #define IPMI_DMI_TYPE_SSIF	0x04
22 
23 struct ipmi_dmi_info {
24 	enum si_type si_type;
25 	unsigned int space; /* addr space for si, intf# for ssif */
26 	unsigned long addr;
27 	u8 slave_addr;
28 	struct ipmi_dmi_info *next;
29 };
30 
31 static struct ipmi_dmi_info *ipmi_dmi_infos;
32 
33 static int ipmi_dmi_nr __initdata;
34 
dmi_add_platform_ipmi(unsigned long base_addr,unsigned int space,u8 slave_addr,int irq,int offset,int type)35 static void __init dmi_add_platform_ipmi(unsigned long base_addr,
36 					 unsigned int space,
37 					 u8 slave_addr,
38 					 int irq,
39 					 int offset,
40 					 int type)
41 {
42 	const char *name;
43 	struct ipmi_dmi_info *info;
44 	struct ipmi_plat_data p;
45 
46 	memset(&p, 0, sizeof(p));
47 
48 	name = "dmi-ipmi-si";
49 	p.iftype = IPMI_PLAT_IF_SI;
50 	switch (type) {
51 	case IPMI_DMI_TYPE_SSIF:
52 		name = "dmi-ipmi-ssif";
53 		p.iftype = IPMI_PLAT_IF_SSIF;
54 		p.type = SI_TYPE_INVALID;
55 		break;
56 	case IPMI_DMI_TYPE_BT:
57 		p.type = SI_BT;
58 		break;
59 	case IPMI_DMI_TYPE_KCS:
60 		p.type = SI_KCS;
61 		break;
62 	case IPMI_DMI_TYPE_SMIC:
63 		p.type = SI_SMIC;
64 		break;
65 	default:
66 		pr_err("Invalid IPMI type: %d\n", type);
67 		return;
68 	}
69 
70 	p.addr = base_addr;
71 	p.space = space;
72 	p.regspacing = offset;
73 	p.irq = irq;
74 	p.slave_addr = slave_addr;
75 	p.addr_source = SI_SMBIOS;
76 
77 	info = kmalloc(sizeof(*info), GFP_KERNEL);
78 	if (!info) {
79 		pr_warn("Could not allocate dmi info\n");
80 	} else {
81 		info->si_type = p.type;
82 		info->space = space;
83 		info->addr = base_addr;
84 		info->slave_addr = slave_addr;
85 		info->next = ipmi_dmi_infos;
86 		ipmi_dmi_infos = info;
87 	}
88 
89 	if (ipmi_platform_add(name, ipmi_dmi_nr, &p))
90 		ipmi_dmi_nr++;
91 }
92 
93 /*
94  * Look up the slave address for a given interface.  This is here
95  * because ACPI doesn't have a slave address while SMBIOS does, but we
96  * prefer using ACPI so the ACPI code can use the IPMI namespace.
97  * This function allows an ACPI-specified IPMI device to look up the
98  * slave address from the DMI table.
99  */
ipmi_dmi_get_slave_addr(enum si_type si_type,unsigned int space,unsigned long base_addr)100 int ipmi_dmi_get_slave_addr(enum si_type si_type, unsigned int space,
101 			    unsigned long base_addr)
102 {
103 	struct ipmi_dmi_info *info = ipmi_dmi_infos;
104 
105 	while (info) {
106 		if (info->si_type == si_type &&
107 		    info->space == space &&
108 		    info->addr == base_addr)
109 			return info->slave_addr;
110 		info = info->next;
111 	}
112 
113 	return 0;
114 }
115 EXPORT_SYMBOL(ipmi_dmi_get_slave_addr);
116 
117 #define DMI_IPMI_MIN_LENGTH	0x10
118 #define DMI_IPMI_VER2_LENGTH	0x12
119 #define DMI_IPMI_TYPE		4
120 #define DMI_IPMI_SLAVEADDR	6
121 #define DMI_IPMI_ADDR		8
122 #define DMI_IPMI_ACCESS		0x10
123 #define DMI_IPMI_IRQ		0x11
124 #define DMI_IPMI_IO_MASK	0xfffe
125 
dmi_decode_ipmi(const struct dmi_header * dm)126 static void __init dmi_decode_ipmi(const struct dmi_header *dm)
127 {
128 	const u8 *data = (const u8 *) dm;
129 	int space = IPMI_IO_ADDR_SPACE;
130 	unsigned long base_addr;
131 	u8 len = dm->length;
132 	u8 slave_addr;
133 	int irq = 0, offset = 0;
134 	int type;
135 
136 	if (len < DMI_IPMI_MIN_LENGTH)
137 		return;
138 
139 	type = data[DMI_IPMI_TYPE];
140 	slave_addr = data[DMI_IPMI_SLAVEADDR];
141 
142 	memcpy(&base_addr, data + DMI_IPMI_ADDR, sizeof(unsigned long));
143 	if (!base_addr) {
144 		pr_err("Base address is zero, assuming no IPMI interface\n");
145 		return;
146 	}
147 	if (len >= DMI_IPMI_VER2_LENGTH) {
148 		if (type == IPMI_DMI_TYPE_SSIF) {
149 			space = 0; /* Match I2C interface 0. */
150 			base_addr = data[DMI_IPMI_ADDR] >> 1;
151 			if (base_addr == 0) {
152 				/*
153 				 * Some broken systems put the I2C address in
154 				 * the slave address field.  We try to
155 				 * accommodate them here.
156 				 */
157 				base_addr = data[DMI_IPMI_SLAVEADDR] >> 1;
158 				slave_addr = 0;
159 			}
160 		} else {
161 			if (base_addr & 1) {
162 				/* I/O */
163 				base_addr &= DMI_IPMI_IO_MASK;
164 			} else {
165 				/* Memory */
166 				space = IPMI_MEM_ADDR_SPACE;
167 			}
168 
169 			/*
170 			 * If bit 4 of byte 0x10 is set, then the lsb
171 			 * for the address is odd.
172 			 */
173 			base_addr |= (data[DMI_IPMI_ACCESS] >> 4) & 1;
174 
175 			irq = data[DMI_IPMI_IRQ];
176 
177 			/*
178 			 * The top two bits of byte 0x10 hold the
179 			 * register spacing.
180 			 */
181 			switch ((data[DMI_IPMI_ACCESS] >> 6) & 3) {
182 			case 0: /* Byte boundaries */
183 				offset = 1;
184 				break;
185 			case 1: /* 32-bit boundaries */
186 				offset = 4;
187 				break;
188 			case 2: /* 16-byte boundaries */
189 				offset = 16;
190 				break;
191 			default:
192 				pr_err("Invalid offset: 0\n");
193 				return;
194 			}
195 		}
196 	} else {
197 		/* Old DMI spec. */
198 		/*
199 		 * Note that technically, the lower bit of the base
200 		 * address should be 1 if the address is I/O and 0 if
201 		 * the address is in memory.  So many systems get that
202 		 * wrong (and all that I have seen are I/O) so we just
203 		 * ignore that bit and assume I/O.  Systems that use
204 		 * memory should use the newer spec, anyway.
205 		 */
206 		base_addr = base_addr & DMI_IPMI_IO_MASK;
207 		offset = 1;
208 	}
209 
210 	dmi_add_platform_ipmi(base_addr, space, slave_addr, irq,
211 			      offset, type);
212 }
213 
scan_for_dmi_ipmi(void)214 static int __init scan_for_dmi_ipmi(void)
215 {
216 	const struct dmi_device *dev = NULL;
217 
218 	while ((dev = dmi_find_device(DMI_DEV_TYPE_IPMI, NULL, dev)))
219 		dmi_decode_ipmi((const struct dmi_header *) dev->device_data);
220 
221 	return 0;
222 }
223 subsys_initcall(scan_for_dmi_ipmi);
224