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
 23struct 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
 31static struct ipmi_dmi_info *ipmi_dmi_infos;
 32
 33static int ipmi_dmi_nr __initdata;
 34
 35static 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 */
100int 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}
115EXPORT_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
126static 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
214static 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}
223subsys_initcall(scan_for_dmi_ipmi);