1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Low-level PCI config space access for OLPC systems who lack the VSA
4 * PCI virtualization software.
5 *
6 * Copyright © 2006 Advanced Micro Devices, Inc.
7 *
8 * The AMD Geode chipset (ie: GX2 processor, cs5536 I/O companion device)
9 * has some I/O functions (display, southbridge, sound, USB HCIs, etc)
10 * that more or less behave like PCI devices, but the hardware doesn't
11 * directly implement the PCI configuration space headers. AMD provides
12 * "VSA" (Virtual System Architecture) software that emulates PCI config
13 * space for these devices, by trapping I/O accesses to PCI config register
14 * (CF8/CFC) and running some code in System Management Mode interrupt state.
15 * On the OLPC platform, we don't want to use that VSA code because
16 * (a) it slows down suspend/resume, and (b) recompiling it requires special
17 * compilers that are hard to get. So instead of letting the complex VSA
18 * code simulate the PCI config registers for the on-chip devices, we
19 * just simulate them the easy way, by inserting the code into the
20 * pci_write_config and pci_read_config path. Most of the config registers
21 * are read-only anyway, so the bulk of the simulation is just table lookup.
22 */
23
24 #include <linux/pci.h>
25 #include <linux/init.h>
26 #include <asm/olpc.h>
27 #include <asm/geode.h>
28 #include <asm/pci_x86.h>
29
30 /*
31 * In the tables below, the first two line (8 longwords) are the
32 * size masks that are used when the higher level PCI code determines
33 * the size of the region by writing ~0 to a base address register
34 * and reading back the result.
35 *
36 * The following lines are the values that are read during normal
37 * PCI config access cycles, i.e. not after just having written
38 * ~0 to a base address register.
39 */
40
41 static const uint32_t lxnb_hdr[] = { /* dev 1 function 0 - devfn = 8 */
42 0x0, 0x0, 0x0, 0x0,
43 0x0, 0x0, 0x0, 0x0,
44
45 0x281022, 0x2200005, 0x6000021, 0x80f808, /* AMD Vendor ID */
46 0x0, 0x0, 0x0, 0x0, /* No virtual registers, hence no BAR */
47 0x0, 0x0, 0x0, 0x28100b,
48 0x0, 0x0, 0x0, 0x0,
49 0x0, 0x0, 0x0, 0x0,
50 0x0, 0x0, 0x0, 0x0,
51 0x0, 0x0, 0x0, 0x0,
52 };
53
54 static const uint32_t gxnb_hdr[] = { /* dev 1 function 0 - devfn = 8 */
55 0xfffffffd, 0x0, 0x0, 0x0,
56 0x0, 0x0, 0x0, 0x0,
57
58 0x28100b, 0x2200005, 0x6000021, 0x80f808, /* NSC Vendor ID */
59 0xac1d, 0x0, 0x0, 0x0, /* I/O BAR - base of virtual registers */
60 0x0, 0x0, 0x0, 0x28100b,
61 0x0, 0x0, 0x0, 0x0,
62 0x0, 0x0, 0x0, 0x0,
63 0x0, 0x0, 0x0, 0x0,
64 0x0, 0x0, 0x0, 0x0,
65 };
66
67 static const uint32_t lxfb_hdr[] = { /* dev 1 function 1 - devfn = 9 */
68 0xff000008, 0xffffc000, 0xffffc000, 0xffffc000,
69 0xffffc000, 0x0, 0x0, 0x0,
70
71 0x20811022, 0x2200003, 0x3000000, 0x0, /* AMD Vendor ID */
72 0xfd000000, 0xfe000000, 0xfe004000, 0xfe008000, /* FB, GP, VG, DF */
73 0xfe00c000, 0x0, 0x0, 0x30100b, /* VIP */
74 0x0, 0x0, 0x0, 0x10e, /* INTA, IRQ14 for graphics accel */
75 0x0, 0x0, 0x0, 0x0,
76 0x3d0, 0x3c0, 0xa0000, 0x0, /* VG IO, VG IO, EGA FB, MONO FB */
77 0x0, 0x0, 0x0, 0x0,
78 };
79
80 static const uint32_t gxfb_hdr[] = { /* dev 1 function 1 - devfn = 9 */
81 0xff800008, 0xffffc000, 0xffffc000, 0xffffc000,
82 0x0, 0x0, 0x0, 0x0,
83
84 0x30100b, 0x2200003, 0x3000000, 0x0, /* NSC Vendor ID */
85 0xfd000000, 0xfe000000, 0xfe004000, 0xfe008000, /* FB, GP, VG, DF */
86 0x0, 0x0, 0x0, 0x30100b,
87 0x0, 0x0, 0x0, 0x0,
88 0x0, 0x0, 0x0, 0x0,
89 0x3d0, 0x3c0, 0xa0000, 0x0, /* VG IO, VG IO, EGA FB, MONO FB */
90 0x0, 0x0, 0x0, 0x0,
91 };
92
93 static const uint32_t aes_hdr[] = { /* dev 1 function 2 - devfn = 0xa */
94 0xffffc000, 0x0, 0x0, 0x0,
95 0x0, 0x0, 0x0, 0x0,
96
97 0x20821022, 0x2a00006, 0x10100000, 0x8, /* NSC Vendor ID */
98 0xfe010000, 0x0, 0x0, 0x0, /* AES registers */
99 0x0, 0x0, 0x0, 0x20821022,
100 0x0, 0x0, 0x0, 0x0,
101 0x0, 0x0, 0x0, 0x0,
102 0x0, 0x0, 0x0, 0x0,
103 0x0, 0x0, 0x0, 0x0,
104 };
105
106
107 static const uint32_t isa_hdr[] = { /* dev f function 0 - devfn = 78 */
108 0xfffffff9, 0xffffff01, 0xffffffc1, 0xffffffe1,
109 0xffffff81, 0xffffffc1, 0x0, 0x0,
110
111 0x20901022, 0x2a00049, 0x6010003, 0x802000,
112 0x18b1, 0x1001, 0x1801, 0x1881, /* SMB-8 GPIO-256 MFGPT-64 IRQ-32 */
113 0x1401, 0x1841, 0x0, 0x20901022, /* PMS-128 ACPI-64 */
114 0x0, 0x0, 0x0, 0x0,
115 0x0, 0x0, 0x0, 0x0,
116 0x0, 0x0, 0x0, 0xaa5b, /* IRQ steering */
117 0x0, 0x0, 0x0, 0x0,
118 };
119
120 static const uint32_t ac97_hdr[] = { /* dev f function 3 - devfn = 7b */
121 0xffffff81, 0x0, 0x0, 0x0,
122 0x0, 0x0, 0x0, 0x0,
123
124 0x20931022, 0x2a00041, 0x4010001, 0x0,
125 0x1481, 0x0, 0x0, 0x0, /* I/O BAR-128 */
126 0x0, 0x0, 0x0, 0x20931022,
127 0x0, 0x0, 0x0, 0x205, /* IntB, IRQ5 */
128 0x0, 0x0, 0x0, 0x0,
129 0x0, 0x0, 0x0, 0x0,
130 0x0, 0x0, 0x0, 0x0,
131 };
132
133 static const uint32_t ohci_hdr[] = { /* dev f function 4 - devfn = 7c */
134 0xfffff000, 0x0, 0x0, 0x0,
135 0x0, 0x0, 0x0, 0x0,
136
137 0x20941022, 0x2300006, 0xc031002, 0x0,
138 0xfe01a000, 0x0, 0x0, 0x0, /* MEMBAR-1000 */
139 0x0, 0x0, 0x0, 0x20941022,
140 0x0, 0x40, 0x0, 0x40a, /* CapPtr INT-D, IRQA */
141 0xc8020001, 0x0, 0x0, 0x0, /* Capabilities - 40 is R/O,
142 44 is mask 8103 (power control) */
143 0x0, 0x0, 0x0, 0x0,
144 0x0, 0x0, 0x0, 0x0,
145 };
146
147 static const uint32_t ehci_hdr[] = { /* dev f function 4 - devfn = 7d */
148 0xfffff000, 0x0, 0x0, 0x0,
149 0x0, 0x0, 0x0, 0x0,
150
151 0x20951022, 0x2300006, 0xc032002, 0x0,
152 0xfe01b000, 0x0, 0x0, 0x0, /* MEMBAR-1000 */
153 0x0, 0x0, 0x0, 0x20951022,
154 0x0, 0x40, 0x0, 0x40a, /* CapPtr INT-D, IRQA */
155 0xc8020001, 0x0, 0x0, 0x0, /* Capabilities - 40 is R/O, 44 is
156 mask 8103 (power control) */
157 0x01000001, 0x0, 0x0, 0x0, /* EECP - see EHCI spec section 2.1.7 */
158 0x2020, 0x0, 0x0, 0x0, /* (EHCI page 8) 60 SBRN (R/O),
159 61 FLADJ (R/W), PORTWAKECAP */
160 };
161
162 static uint32_t ff_loc = ~0;
163 static uint32_t zero_loc;
164 static int bar_probing; /* Set after a write of ~0 to a BAR */
165 static int is_lx;
166
167 #define NB_SLOT 0x1 /* Northbridge - GX chip - Device 1 */
168 #define SB_SLOT 0xf /* Southbridge - CS5536 chip - Device F */
169
170 static int is_simulated(unsigned int bus, unsigned int devfn)
171 {
172 return (!bus && ((PCI_SLOT(devfn) == NB_SLOT) ||
173 (PCI_SLOT(devfn) == SB_SLOT)));
174 }
175
176 static uint32_t *hdr_addr(const uint32_t *hdr, int reg)
177 {
178 uint32_t addr;
179
180 /*
181 * This is a little bit tricky. The header maps consist of
182 * 0x20 bytes of size masks, followed by 0x70 bytes of header data.
183 * In the normal case, when not probing a BAR's size, we want
184 * to access the header data, so we add 0x20 to the reg offset,
185 * thus skipping the size mask area.
186 * In the BAR probing case, we want to access the size mask for
187 * the BAR, so we subtract 0x10 (the config header offset for
188 * BAR0), and don't skip the size mask area.
189 */
190
191 addr = (uint32_t)hdr + reg + (bar_probing ? -0x10 : 0x20);
192
193 bar_probing = 0;
194 return (uint32_t *)addr;
195 }
196
197 static int pci_olpc_read(unsigned int seg, unsigned int bus,
198 unsigned int devfn, int reg, int len, uint32_t *value)
199 {
200 uint32_t *addr;
201
202 WARN_ON(seg);
203
204 /* Use the hardware mechanism for non-simulated devices */
205 if (!is_simulated(bus, devfn))
206 return pci_direct_conf1.read(seg, bus, devfn, reg, len, value);
207
208 /*
209 * No device has config registers past 0x70, so we save table space
210 * by not storing entries for the nonexistent registers
211 */
212 if (reg >= 0x70)
213 addr = &zero_loc;
214 else {
215 switch (devfn) {
216 case 0x8:
217 addr = hdr_addr(is_lx ? lxnb_hdr : gxnb_hdr, reg);
218 break;
219 case 0x9:
220 addr = hdr_addr(is_lx ? lxfb_hdr : gxfb_hdr, reg);
221 break;
222 case 0xa:
223 addr = is_lx ? hdr_addr(aes_hdr, reg) : &ff_loc;
224 break;
225 case 0x78:
226 addr = hdr_addr(isa_hdr, reg);
227 break;
228 case 0x7b:
229 addr = hdr_addr(ac97_hdr, reg);
230 break;
231 case 0x7c:
232 addr = hdr_addr(ohci_hdr, reg);
233 break;
234 case 0x7d:
235 addr = hdr_addr(ehci_hdr, reg);
236 break;
237 default:
238 addr = &ff_loc;
239 break;
240 }
241 }
242 switch (len) {
243 case 1:
244 *value = *(uint8_t *)addr;
245 break;
246 case 2:
247 *value = *(uint16_t *)addr;
248 break;
249 case 4:
250 *value = *addr;
251 break;
252 default:
253 BUG();
254 }
255
256 return 0;
257 }
258
259 static int pci_olpc_write(unsigned int seg, unsigned int bus,
260 unsigned int devfn, int reg, int len, uint32_t value)
261 {
262 WARN_ON(seg);
263
264 /* Use the hardware mechanism for non-simulated devices */
265 if (!is_simulated(bus, devfn))
266 return pci_direct_conf1.write(seg, bus, devfn, reg, len, value);
267
268 /* XXX we may want to extend this to simulate EHCI power management */
269
270 /*
271 * Mostly we just discard writes, but if the write is a size probe
272 * (i.e. writing ~0 to a BAR), we remember it and arrange to return
273 * the appropriate size mask on the next read. This is cheating
274 * to some extent, because it depends on the fact that the next
275 * access after such a write will always be a read to the same BAR.
276 */
277
278 if ((reg >= 0x10) && (reg < 0x2c)) {
279 /* write is to a BAR */
280 if (value == ~0)
281 bar_probing = 1;
282 } else {
283 /*
284 * No warning on writes to ROM BAR, CMD, LATENCY_TIMER,
285 * CACHE_LINE_SIZE, or PM registers.
286 */
287 if ((reg != PCI_ROM_ADDRESS) && (reg != PCI_COMMAND_MASTER) &&
288 (reg != PCI_LATENCY_TIMER) &&
289 (reg != PCI_CACHE_LINE_SIZE) && (reg != 0x44))
290 printk(KERN_WARNING "OLPC PCI: Config write to devfn"
291 " %x reg %x value %x\n", devfn, reg, value);
292 }
293
294 return 0;
295 }
296
297 static const struct pci_raw_ops pci_olpc_conf = {
298 .read = pci_olpc_read,
299 .write = pci_olpc_write,
300 };
301
302 int __init pci_olpc_init(void)
303 {
304 printk(KERN_INFO "PCI: Using configuration type OLPC XO-1\n");
305 raw_pci_ops = &pci_olpc_conf;
306 is_lx = is_geode_lx();
307 return 0;
308 }
309
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