1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * MTD map driver for BIOS Flash on Intel SCB2 boards
4 * Copyright (C) 2002 Sun Microsystems, Inc.
5 * Tim Hockin <thockin@sun.com>
6 *
7 * A few notes on this MTD map:
8 *
9 * This was developed with a small number of SCB2 boards to test on.
10 * Hopefully, Intel has not introducted too many unaccounted variables in the
11 * making of this board.
12 *
13 * The BIOS marks its own memory region as 'reserved' in the e820 map. We
14 * try to request it here, but if it fails, we carry on anyway.
15 *
16 * This is how the chip is attached, so said the schematic:
17 * * a 4 MiB (32 Mib) 16 bit chip
18 * * a 1 MiB memory region
19 * * A20 and A21 pulled up
20 * * D8-D15 ignored
21 * What this means is that, while we are addressing bytes linearly, we are
22 * really addressing words, and discarding the other byte. This means that
23 * the chip MUST BE at least 2 MiB. This also means that every block is
24 * actually half as big as the chip reports. It also means that accesses of
25 * logical address 0 hit higher-address sections of the chip, not physical 0.
26 * One can only hope that these 4MiB x16 chips were a lot cheaper than 1MiB x8
27 * chips.
28 *
29 * This driver assumes the chip is not write-protected by an external signal.
30 * As of the this writing, that is true, but may change, just to spite me.
31 *
32 * The actual BIOS layout has been mostly reverse engineered. Intel BIOS
33 * updates for this board include 10 related (*.bio - &.bi9) binary files and
34 * another separate (*.bbo) binary file. The 10 files are 64k of data + a
35 * small header. If the headers are stripped off, the 10 64k files can be
36 * concatenated into a 640k image. This is your BIOS image, proper. The
37 * separate .bbo file also has a small header. It is the 'Boot Block'
38 * recovery BIOS. Once the header is stripped, no further prep is needed.
39 * As best I can tell, the BIOS is arranged as such:
40 * offset 0x00000 to 0x4ffff (320k): unknown - SCSI BIOS, etc?
41 * offset 0x50000 to 0xeffff (640k): BIOS proper
42 * offset 0xf0000 ty 0xfffff (64k): Boot Block region
43 *
44 * Intel's BIOS update program flashes the BIOS and Boot Block in separate
45 * steps. Probably a wise thing to do.
46 */
47
48 #include <linux/module.h>
49 #include <linux/types.h>
50 #include <linux/kernel.h>
51 #include <asm/io.h>
52 #include <linux/mtd/mtd.h>
53 #include <linux/mtd/map.h>
54 #include <linux/mtd/cfi.h>
55 #include <linux/pci.h>
56 #include <linux/pci_ids.h>
57
58 #define MODNAME "scb2_flash"
59 #define SCB2_ADDR 0xfff00000
60 #define SCB2_WINDOW 0x00100000
61
62
63 static void __iomem *scb2_ioaddr;
64 static struct mtd_info *scb2_mtd;
65 static struct map_info scb2_map = {
66 .name = "SCB2 BIOS Flash",
67 .size = 0,
68 .bankwidth = 1,
69 };
70 static int region_fail;
71
72 static int scb2_fixup_mtd(struct mtd_info *mtd)
73 {
74 int i;
75 int done = 0;
76 struct map_info *map = mtd->priv;
77 struct cfi_private *cfi = map->fldrv_priv;
78
79 /* barf if this doesn't look right */
80 if (cfi->cfiq->InterfaceDesc != CFI_INTERFACE_X16_ASYNC) {
81 printk(KERN_ERR MODNAME ": unsupported InterfaceDesc: %#x\n",
82 cfi->cfiq->InterfaceDesc);
83 return -1;
84 }
85
86 /* I wasn't here. I didn't see. dwmw2. */
87
88 /* the chip is sometimes bigger than the map - what a waste */
89 mtd->size = map->size;
90
91 /*
92 * We only REALLY get half the chip, due to the way it is
93 * wired up - D8-D15 are tossed away. We read linear bytes,
94 * but in reality we are getting 1/2 of each 16-bit read,
95 * which LOOKS linear to us. Because CFI code accounts for
96 * things like lock/unlock/erase by eraseregions, we need to
97 * fudge them to reflect this. Erases go like this:
98 * * send an erase to an address
99 * * the chip samples the address and erases the block
100 * * add the block erasesize to the address and repeat
101 * -- the problem is that addresses are 16-bit addressable
102 * -- we end up erasing every-other block
103 */
104 mtd->erasesize /= 2;
105 for (i = 0; i < mtd->numeraseregions; i++) {
106 struct mtd_erase_region_info *region = &mtd->eraseregions[i];
107 region->erasesize /= 2;
108 }
109
110 /*
111 * If the chip is bigger than the map, it is wired with the high
112 * address lines pulled up. This makes us access the top portion of
113 * the chip, so all our erase-region info is wrong. Start cutting from
114 * the bottom.
115 */
116 for (i = 0; !done && i < mtd->numeraseregions; i++) {
117 struct mtd_erase_region_info *region = &mtd->eraseregions[i];
118
119 if (region->numblocks * region->erasesize > mtd->size) {
120 region->numblocks = ((unsigned long)mtd->size /
121 region->erasesize);
122 done = 1;
123 } else {
124 region->numblocks = 0;
125 }
126 region->offset = 0;
127 }
128
129 return 0;
130 }
131
132 /* CSB5's 'Function Control Register' has bits for decoding @ >= 0xffc00000 */
133 #define CSB5_FCR 0x41
134 #define CSB5_FCR_DECODE_ALL 0x0e
135 static int scb2_flash_probe(struct pci_dev *dev,
136 const struct pci_device_id *ent)
137 {
138 u8 reg;
139
140 /* enable decoding of the flash region in the south bridge */
141 pci_read_config_byte(dev, CSB5_FCR, ®);
142 pci_write_config_byte(dev, CSB5_FCR, reg | CSB5_FCR_DECODE_ALL);
143
144 if (!request_mem_region(SCB2_ADDR, SCB2_WINDOW, scb2_map.name)) {
145 /*
146 * The BIOS seems to mark the flash region as 'reserved'
147 * in the e820 map. Warn and go about our business.
148 */
149 printk(KERN_WARNING MODNAME
150 ": warning - can't reserve rom window, continuing\n");
151 region_fail = 1;
152 }
153
154 /* remap the IO window (w/o caching) */
155 scb2_ioaddr = ioremap_nocache(SCB2_ADDR, SCB2_WINDOW);
156 if (!scb2_ioaddr) {
157 printk(KERN_ERR MODNAME ": Failed to ioremap window!\n");
158 if (!region_fail)
159 release_mem_region(SCB2_ADDR, SCB2_WINDOW);
160 return -ENOMEM;
161 }
162
163 scb2_map.phys = SCB2_ADDR;
164 scb2_map.virt = scb2_ioaddr;
165 scb2_map.size = SCB2_WINDOW;
166
167 simple_map_init(&scb2_map);
168
169 /* try to find a chip */
170 scb2_mtd = do_map_probe("cfi_probe", &scb2_map);
171
172 if (!scb2_mtd) {
173 printk(KERN_ERR MODNAME ": flash probe failed!\n");
174 iounmap(scb2_ioaddr);
175 if (!region_fail)
176 release_mem_region(SCB2_ADDR, SCB2_WINDOW);
177 return -ENODEV;
178 }
179
180 scb2_mtd->owner = THIS_MODULE;
181 if (scb2_fixup_mtd(scb2_mtd) < 0) {
182 mtd_device_unregister(scb2_mtd);
183 map_destroy(scb2_mtd);
184 iounmap(scb2_ioaddr);
185 if (!region_fail)
186 release_mem_region(SCB2_ADDR, SCB2_WINDOW);
187 return -ENODEV;
188 }
189
190 printk(KERN_NOTICE MODNAME ": chip size 0x%llx at offset 0x%llx\n",
191 (unsigned long long)scb2_mtd->size,
192 (unsigned long long)(SCB2_WINDOW - scb2_mtd->size));
193
194 mtd_device_register(scb2_mtd, NULL, 0);
195
196 return 0;
197 }
198
199 static void scb2_flash_remove(struct pci_dev *dev)
200 {
201 if (!scb2_mtd)
202 return;
203
204 /* disable flash writes */
205 mtd_lock(scb2_mtd, 0, scb2_mtd->size);
206
207 mtd_device_unregister(scb2_mtd);
208 map_destroy(scb2_mtd);
209
210 iounmap(scb2_ioaddr);
211 scb2_ioaddr = NULL;
212
213 if (!region_fail)
214 release_mem_region(SCB2_ADDR, SCB2_WINDOW);
215 }
216
217 static struct pci_device_id scb2_flash_pci_ids[] = {
218 {
219 .vendor = PCI_VENDOR_ID_SERVERWORKS,
220 .device = PCI_DEVICE_ID_SERVERWORKS_CSB5,
221 .subvendor = PCI_ANY_ID,
222 .subdevice = PCI_ANY_ID
223 },
224 { 0, }
225 };
226
227 static struct pci_driver scb2_flash_driver = {
228 .name = "Intel SCB2 BIOS Flash",
229 .id_table = scb2_flash_pci_ids,
230 .probe = scb2_flash_probe,
231 .remove = scb2_flash_remove,
232 };
233
234 module_pci_driver(scb2_flash_driver);
235
236 MODULE_LICENSE("GPL");
237 MODULE_AUTHOR("Tim Hockin <thockin@sun.com>");
238 MODULE_DESCRIPTION("MTD map driver for Intel SCB2 BIOS Flash");
239 MODULE_DEVICE_TABLE(pci, scb2_flash_pci_ids);