1/*
2 * RNG driver for Intel RNGs
3 *
4 * Copyright 2005 (c) MontaVista Software, Inc.
5 *
6 * with the majority of the code coming from:
7 *
8 * Hardware driver for the Intel/AMD/VIA Random Number Generators (RNG)
9 * (c) Copyright 2003 Red Hat Inc <jgarzik@redhat.com>
10 *
11 * derived from
12 *
13 * Hardware driver for the AMD 768 Random Number Generator (RNG)
14 * (c) Copyright 2001 Red Hat Inc
15 *
16 * derived from
17 *
18 * Hardware driver for Intel i810 Random Number Generator (RNG)
19 * Copyright 2000,2001 Jeff Garzik <jgarzik@pobox.com>
20 * Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com>
21 *
22 * This file is licensed under the terms of the GNU General Public
23 * License version 2. This program is licensed "as is" without any
24 * warranty of any kind, whether express or implied.
25 */
26
27#include <linux/hw_random.h>
28#include <linux/io.h>
29#include <linux/kernel.h>
30#include <linux/module.h>
31#include <linux/pci.h>
32#include <linux/stop_machine.h>
33#include <linux/delay.h>
34#include <linux/slab.h>
35
36
37#define PFX KBUILD_MODNAME ": "
38
39/*
40 * RNG registers
41 */
42#define INTEL_RNG_HW_STATUS 0
43#define INTEL_RNG_PRESENT 0x40
44#define INTEL_RNG_ENABLED 0x01
45#define INTEL_RNG_STATUS 1
46#define INTEL_RNG_DATA_PRESENT 0x01
47#define INTEL_RNG_DATA 2
48
49/*
50 * Magic address at which Intel PCI bridges locate the RNG
51 */
52#define INTEL_RNG_ADDR 0xFFBC015F
53#define INTEL_RNG_ADDR_LEN 3
54
55/*
56 * LPC bridge PCI config space registers
57 */
58#define FWH_DEC_EN1_REG_OLD 0xe3
59#define FWH_DEC_EN1_REG_NEW 0xd9 /* high byte of 16-bit register */
60#define FWH_F8_EN_MASK 0x80
61
62#define BIOS_CNTL_REG_OLD 0x4e
63#define BIOS_CNTL_REG_NEW 0xdc
64#define BIOS_CNTL_WRITE_ENABLE_MASK 0x01
65#define BIOS_CNTL_LOCK_ENABLE_MASK 0x02
66
67/*
68 * Magic address at which Intel Firmware Hubs get accessed
69 */
70#define INTEL_FWH_ADDR 0xffff0000
71#define INTEL_FWH_ADDR_LEN 2
72
73/*
74 * Intel Firmware Hub command codes (write to any address inside the device)
75 */
76#define INTEL_FWH_RESET_CMD 0xff /* aka READ_ARRAY */
77#define INTEL_FWH_READ_ID_CMD 0x90
78
79/*
80 * Intel Firmware Hub Read ID command result addresses
81 */
82#define INTEL_FWH_MANUFACTURER_CODE_ADDRESS 0x000000
83#define INTEL_FWH_DEVICE_CODE_ADDRESS 0x000001
84
85/*
86 * Intel Firmware Hub Read ID command result values
87 */
88#define INTEL_FWH_MANUFACTURER_CODE 0x89
89#define INTEL_FWH_DEVICE_CODE_8M 0xac
90#define INTEL_FWH_DEVICE_CODE_4M 0xad
91
92/*
93 * Data for PCI driver interface
94 *
95 * This data only exists for exporting the supported
96 * PCI ids via MODULE_DEVICE_TABLE. We do not actually
97 * register a pci_driver, because someone else might one day
98 * want to register another driver on the same PCI id.
99 */
100static const struct pci_device_id pci_tbl[] = {
101/* AA
102 { PCI_DEVICE(0x8086, 0x2418) }, */
103 { PCI_DEVICE(0x8086, 0x2410) }, /* AA */
104/* AB
105 { PCI_DEVICE(0x8086, 0x2428) }, */
106 { PCI_DEVICE(0x8086, 0x2420) }, /* AB */
107/* ??
108 { PCI_DEVICE(0x8086, 0x2430) }, */
109/* BAM, CAM, DBM, FBM, GxM
110 { PCI_DEVICE(0x8086, 0x2448) }, */
111 { PCI_DEVICE(0x8086, 0x244c) }, /* BAM */
112 { PCI_DEVICE(0x8086, 0x248c) }, /* CAM */
113 { PCI_DEVICE(0x8086, 0x24cc) }, /* DBM */
114 { PCI_DEVICE(0x8086, 0x2641) }, /* FBM */
115 { PCI_DEVICE(0x8086, 0x27b9) }, /* GxM */
116 { PCI_DEVICE(0x8086, 0x27bd) }, /* GxM DH */
117/* BA, CA, DB, Ex, 6300, Fx, 631x/632x, Gx
118 { PCI_DEVICE(0x8086, 0x244e) }, */
119 { PCI_DEVICE(0x8086, 0x2440) }, /* BA */
120 { PCI_DEVICE(0x8086, 0x2480) }, /* CA */
121 { PCI_DEVICE(0x8086, 0x24c0) }, /* DB */
122 { PCI_DEVICE(0x8086, 0x24d0) }, /* Ex */
123 { PCI_DEVICE(0x8086, 0x25a1) }, /* 6300 */
124 { PCI_DEVICE(0x8086, 0x2640) }, /* Fx */
125 { PCI_DEVICE(0x8086, 0x2670) }, /* 631x/632x */
126 { PCI_DEVICE(0x8086, 0x2671) }, /* 631x/632x */
127 { PCI_DEVICE(0x8086, 0x2672) }, /* 631x/632x */
128 { PCI_DEVICE(0x8086, 0x2673) }, /* 631x/632x */
129 { PCI_DEVICE(0x8086, 0x2674) }, /* 631x/632x */
130 { PCI_DEVICE(0x8086, 0x2675) }, /* 631x/632x */
131 { PCI_DEVICE(0x8086, 0x2676) }, /* 631x/632x */
132 { PCI_DEVICE(0x8086, 0x2677) }, /* 631x/632x */
133 { PCI_DEVICE(0x8086, 0x2678) }, /* 631x/632x */
134 { PCI_DEVICE(0x8086, 0x2679) }, /* 631x/632x */
135 { PCI_DEVICE(0x8086, 0x267a) }, /* 631x/632x */
136 { PCI_DEVICE(0x8086, 0x267b) }, /* 631x/632x */
137 { PCI_DEVICE(0x8086, 0x267c) }, /* 631x/632x */
138 { PCI_DEVICE(0x8086, 0x267d) }, /* 631x/632x */
139 { PCI_DEVICE(0x8086, 0x267e) }, /* 631x/632x */
140 { PCI_DEVICE(0x8086, 0x267f) }, /* 631x/632x */
141 { PCI_DEVICE(0x8086, 0x27b8) }, /* Gx */
142/* E
143 { PCI_DEVICE(0x8086, 0x245e) }, */
144 { PCI_DEVICE(0x8086, 0x2450) }, /* E */
145 { 0, }, /* terminate list */
146};
147MODULE_DEVICE_TABLE(pci, pci_tbl);
148
149static __initdata int no_fwh_detect;
150module_param(no_fwh_detect, int, 0);
151MODULE_PARM_DESC(no_fwh_detect, "Skip FWH detection:\n"
152 " positive value - skip if FWH space locked read-only\n"
153 " negative value - skip always");
154
155static inline u8 hwstatus_get(void __iomem *mem)
156{
157 return readb(addr: mem + INTEL_RNG_HW_STATUS);
158}
159
160static inline u8 hwstatus_set(void __iomem *mem,
161 u8 hw_status)
162{
163 writeb(val: hw_status, addr: mem + INTEL_RNG_HW_STATUS);
164 return hwstatus_get(mem);
165}
166
167static int intel_rng_data_present(struct hwrng *rng, int wait)
168{
169 void __iomem *mem = (void __iomem *)rng->priv;
170 int data, i;
171
172 for (i = 0; i < 20; i++) {
173 data = !!(readb(addr: mem + INTEL_RNG_STATUS) &
174 INTEL_RNG_DATA_PRESENT);
175 if (data || !wait)
176 break;
177 udelay(10);
178 }
179 return data;
180}
181
182static int intel_rng_data_read(struct hwrng *rng, u32 *data)
183{
184 void __iomem *mem = (void __iomem *)rng->priv;
185
186 *data = readb(addr: mem + INTEL_RNG_DATA);
187
188 return 1;
189}
190
191static int intel_rng_init(struct hwrng *rng)
192{
193 void __iomem *mem = (void __iomem *)rng->priv;
194 u8 hw_status;
195 int err = -EIO;
196
197 hw_status = hwstatus_get(mem);
198 /* turn RNG h/w on, if it's off */
199 if ((hw_status & INTEL_RNG_ENABLED) == 0)
200 hw_status = hwstatus_set(mem, hw_status: hw_status | INTEL_RNG_ENABLED);
201 if ((hw_status & INTEL_RNG_ENABLED) == 0) {
202 pr_err(PFX "cannot enable RNG, aborting\n");
203 goto out;
204 }
205 err = 0;
206out:
207 return err;
208}
209
210static void intel_rng_cleanup(struct hwrng *rng)
211{
212 void __iomem *mem = (void __iomem *)rng->priv;
213 u8 hw_status;
214
215 hw_status = hwstatus_get(mem);
216 if (hw_status & INTEL_RNG_ENABLED)
217 hwstatus_set(mem, hw_status: hw_status & ~INTEL_RNG_ENABLED);
218 else
219 pr_warn(PFX "unusual: RNG already disabled\n");
220}
221
222
223static struct hwrng intel_rng = {
224 .name = "intel",
225 .init = intel_rng_init,
226 .cleanup = intel_rng_cleanup,
227 .data_present = intel_rng_data_present,
228 .data_read = intel_rng_data_read,
229};
230
231struct intel_rng_hw {
232 struct pci_dev *dev;
233 void __iomem *mem;
234 u8 bios_cntl_off;
235 u8 bios_cntl_val;
236 u8 fwh_dec_en1_off;
237 u8 fwh_dec_en1_val;
238};
239
240static int __init intel_rng_hw_init(void *_intel_rng_hw)
241{
242 struct intel_rng_hw *intel_rng_hw = _intel_rng_hw;
243 u8 mfc, dvc;
244
245 /* interrupts disabled in stop_machine call */
246
247 if (!(intel_rng_hw->fwh_dec_en1_val & FWH_F8_EN_MASK))
248 pci_write_config_byte(dev: intel_rng_hw->dev,
249 where: intel_rng_hw->fwh_dec_en1_off,
250 val: intel_rng_hw->fwh_dec_en1_val |
251 FWH_F8_EN_MASK);
252 if (!(intel_rng_hw->bios_cntl_val & BIOS_CNTL_WRITE_ENABLE_MASK))
253 pci_write_config_byte(dev: intel_rng_hw->dev,
254 where: intel_rng_hw->bios_cntl_off,
255 val: intel_rng_hw->bios_cntl_val |
256 BIOS_CNTL_WRITE_ENABLE_MASK);
257
258 writeb(INTEL_FWH_RESET_CMD, addr: intel_rng_hw->mem);
259 writeb(INTEL_FWH_READ_ID_CMD, addr: intel_rng_hw->mem);
260 mfc = readb(addr: intel_rng_hw->mem + INTEL_FWH_MANUFACTURER_CODE_ADDRESS);
261 dvc = readb(addr: intel_rng_hw->mem + INTEL_FWH_DEVICE_CODE_ADDRESS);
262 writeb(INTEL_FWH_RESET_CMD, addr: intel_rng_hw->mem);
263
264 if (!(intel_rng_hw->bios_cntl_val &
265 (BIOS_CNTL_LOCK_ENABLE_MASK|BIOS_CNTL_WRITE_ENABLE_MASK)))
266 pci_write_config_byte(dev: intel_rng_hw->dev,
267 where: intel_rng_hw->bios_cntl_off,
268 val: intel_rng_hw->bios_cntl_val);
269 if (!(intel_rng_hw->fwh_dec_en1_val & FWH_F8_EN_MASK))
270 pci_write_config_byte(dev: intel_rng_hw->dev,
271 where: intel_rng_hw->fwh_dec_en1_off,
272 val: intel_rng_hw->fwh_dec_en1_val);
273
274 if (mfc != INTEL_FWH_MANUFACTURER_CODE ||
275 (dvc != INTEL_FWH_DEVICE_CODE_8M &&
276 dvc != INTEL_FWH_DEVICE_CODE_4M)) {
277 pr_notice(PFX "FWH not detected\n");
278 return -ENODEV;
279 }
280
281 return 0;
282}
283
284static int __init intel_init_hw_struct(struct intel_rng_hw *intel_rng_hw,
285 struct pci_dev *dev)
286{
287 intel_rng_hw->bios_cntl_val = 0xff;
288 intel_rng_hw->fwh_dec_en1_val = 0xff;
289 intel_rng_hw->dev = dev;
290
291 /* Check for Intel 82802 */
292 if (dev->device < 0x2640) {
293 intel_rng_hw->fwh_dec_en1_off = FWH_DEC_EN1_REG_OLD;
294 intel_rng_hw->bios_cntl_off = BIOS_CNTL_REG_OLD;
295 } else {
296 intel_rng_hw->fwh_dec_en1_off = FWH_DEC_EN1_REG_NEW;
297 intel_rng_hw->bios_cntl_off = BIOS_CNTL_REG_NEW;
298 }
299
300 pci_read_config_byte(dev, where: intel_rng_hw->fwh_dec_en1_off,
301 val: &intel_rng_hw->fwh_dec_en1_val);
302 pci_read_config_byte(dev, where: intel_rng_hw->bios_cntl_off,
303 val: &intel_rng_hw->bios_cntl_val);
304
305 if ((intel_rng_hw->bios_cntl_val &
306 (BIOS_CNTL_LOCK_ENABLE_MASK|BIOS_CNTL_WRITE_ENABLE_MASK))
307 == BIOS_CNTL_LOCK_ENABLE_MASK) {
308 static __initdata /*const*/ char warning[] =
309PFX "Firmware space is locked read-only. If you can't or\n"
310PFX "don't want to disable this in firmware setup, and if\n"
311PFX "you are certain that your system has a functional\n"
312PFX "RNG, try using the 'no_fwh_detect' option.\n";
313
314 if (no_fwh_detect)
315 return -ENODEV;
316 pr_warn("%s", warning);
317 return -EBUSY;
318 }
319
320 intel_rng_hw->mem = ioremap(INTEL_FWH_ADDR, INTEL_FWH_ADDR_LEN);
321 if (intel_rng_hw->mem == NULL)
322 return -EBUSY;
323
324 return 0;
325}
326
327
328static int __init intel_rng_mod_init(void)
329{
330 int err = -ENODEV;
331 int i;
332 struct pci_dev *dev = NULL;
333 void __iomem *mem;
334 u8 hw_status;
335 struct intel_rng_hw *intel_rng_hw;
336
337 for (i = 0; !dev && pci_tbl[i].vendor; ++i)
338 dev = pci_get_device(vendor: pci_tbl[i].vendor, device: pci_tbl[i].device,
339 NULL);
340
341 if (!dev)
342 goto out; /* Device not found. */
343
344 if (no_fwh_detect < 0) {
345 pci_dev_put(dev);
346 goto fwh_done;
347 }
348
349 intel_rng_hw = kmalloc(size: sizeof(*intel_rng_hw), GFP_KERNEL);
350 if (!intel_rng_hw) {
351 pci_dev_put(dev);
352 goto out;
353 }
354
355 err = intel_init_hw_struct(intel_rng_hw, dev);
356 if (err) {
357 pci_dev_put(dev);
358 kfree(objp: intel_rng_hw);
359 if (err == -ENODEV)
360 goto fwh_done;
361 goto out;
362 }
363
364 /*
365 * Since the BIOS code/data is going to disappear from its normal
366 * location with the Read ID command, all activity on the system
367 * must be stopped until the state is back to normal.
368 *
369 * Use stop_machine because IPIs can be blocked by disabling
370 * interrupts.
371 */
372 err = stop_machine(fn: intel_rng_hw_init, data: intel_rng_hw, NULL);
373 pci_dev_put(dev);
374 iounmap(addr: intel_rng_hw->mem);
375 kfree(objp: intel_rng_hw);
376 if (err)
377 goto out;
378
379fwh_done:
380 err = -ENOMEM;
381 mem = ioremap(INTEL_RNG_ADDR, INTEL_RNG_ADDR_LEN);
382 if (!mem)
383 goto out;
384 intel_rng.priv = (unsigned long)mem;
385
386 /* Check for Random Number Generator */
387 err = -ENODEV;
388 hw_status = hwstatus_get(mem);
389 if ((hw_status & INTEL_RNG_PRESENT) == 0) {
390 iounmap(addr: mem);
391 goto out;
392 }
393
394 pr_info("Intel 82802 RNG detected\n");
395 err = hwrng_register(rng: &intel_rng);
396 if (err) {
397 pr_err(PFX "RNG registering failed (%d)\n",
398 err);
399 iounmap(addr: mem);
400 }
401out:
402 return err;
403
404}
405
406static void __exit intel_rng_mod_exit(void)
407{
408 void __iomem *mem = (void __iomem *)intel_rng.priv;
409
410 hwrng_unregister(rng: &intel_rng);
411 iounmap(addr: mem);
412}
413
414module_init(intel_rng_mod_init);
415module_exit(intel_rng_mod_exit);
416
417MODULE_DESCRIPTION("H/W RNG driver for Intel chipsets");
418MODULE_LICENSE("GPL");
419

source code of linux/drivers/char/hw_random/intel-rng.c