V4L/DVB (6963): tda18271: store IF frequency in a u16 instead of u32
[linux-2.6] / drivers / media / video / mt20xx.c
1 /*
2  * i2c tv tuner chip device driver
3  * controls microtune tuners, mt2032 + mt2050 at the moment.
4  *
5  * This "mt20xx" module was split apart from the original "tuner" module.
6  */
7 #include <linux/delay.h>
8 #include <linux/i2c.h>
9 #include <linux/videodev.h>
10 #include "tuner-i2c.h"
11 #include "mt20xx.h"
12
13 static int debug = 0;
14 module_param(debug, int, 0644);
15 MODULE_PARM_DESC(debug, "enable verbose debug messages");
16
17 #define PREFIX "mt20xx"
18
19 /* ---------------------------------------------------------------------- */
20
21 static unsigned int optimize_vco  = 1;
22 module_param(optimize_vco,      int, 0644);
23
24 static unsigned int tv_antenna    = 1;
25 module_param(tv_antenna,        int, 0644);
26
27 static unsigned int radio_antenna = 0;
28 module_param(radio_antenna,     int, 0644);
29
30 /* ---------------------------------------------------------------------- */
31
32 #define MT2032 0x04
33 #define MT2030 0x06
34 #define MT2040 0x07
35 #define MT2050 0x42
36
37 static char *microtune_part[] = {
38         [ MT2030 ] = "MT2030",
39         [ MT2032 ] = "MT2032",
40         [ MT2040 ] = "MT2040",
41         [ MT2050 ] = "MT2050",
42 };
43
44 struct microtune_priv {
45         struct tuner_i2c_props i2c_props;
46
47         unsigned int xogc;
48         //unsigned int radio_if2;
49
50         u32 frequency;
51 };
52
53 static int microtune_release(struct dvb_frontend *fe)
54 {
55         kfree(fe->tuner_priv);
56         fe->tuner_priv = NULL;
57
58         return 0;
59 }
60
61 static int microtune_get_frequency(struct dvb_frontend *fe, u32 *frequency)
62 {
63         struct microtune_priv *priv = fe->tuner_priv;
64         *frequency = priv->frequency;
65         return 0;
66 }
67
68 // IsSpurInBand()?
69 static int mt2032_spurcheck(struct dvb_frontend *fe,
70                             int f1, int f2, int spectrum_from,int spectrum_to)
71 {
72         struct microtune_priv *priv = fe->tuner_priv;
73         int n1=1,n2,f;
74
75         f1=f1/1000; //scale to kHz to avoid 32bit overflows
76         f2=f2/1000;
77         spectrum_from/=1000;
78         spectrum_to/=1000;
79
80         tuner_dbg("spurcheck f1=%d f2=%d  from=%d to=%d\n",
81                   f1,f2,spectrum_from,spectrum_to);
82
83         do {
84             n2=-n1;
85             f=n1*(f1-f2);
86             do {
87                 n2--;
88                 f=f-f2;
89                 tuner_dbg("spurtest n1=%d n2=%d ftest=%d\n",n1,n2,f);
90
91                 if( (f>spectrum_from) && (f<spectrum_to))
92                         tuner_dbg("mt2032 spurcheck triggered: %d\n",n1);
93             } while ( (f>(f2-spectrum_to)) || (n2>-5));
94             n1++;
95         } while (n1<5);
96
97         return 1;
98 }
99
100 static int mt2032_compute_freq(struct dvb_frontend *fe,
101                                unsigned int rfin,
102                                unsigned int if1, unsigned int if2,
103                                unsigned int spectrum_from,
104                                unsigned int spectrum_to,
105                                unsigned char *buf,
106                                int *ret_sel,
107                                unsigned int xogc) //all in Hz
108 {
109         struct microtune_priv *priv = fe->tuner_priv;
110         unsigned int fref,lo1,lo1n,lo1a,s,sel,lo1freq, desired_lo1,
111                 desired_lo2,lo2,lo2n,lo2a,lo2num,lo2freq;
112
113         fref= 5250 *1000; //5.25MHz
114         desired_lo1=rfin+if1;
115
116         lo1=(2*(desired_lo1/1000)+(fref/1000)) / (2*fref/1000);
117         lo1n=lo1/8;
118         lo1a=lo1-(lo1n*8);
119
120         s=rfin/1000/1000+1090;
121
122         if(optimize_vco) {
123                 if(s>1890) sel=0;
124                 else if(s>1720) sel=1;
125                 else if(s>1530) sel=2;
126                 else if(s>1370) sel=3;
127                 else sel=4; // >1090
128         }
129         else {
130                 if(s>1790) sel=0; // <1958
131                 else if(s>1617) sel=1;
132                 else if(s>1449) sel=2;
133                 else if(s>1291) sel=3;
134                 else sel=4; // >1090
135         }
136         *ret_sel=sel;
137
138         lo1freq=(lo1a+8*lo1n)*fref;
139
140         tuner_dbg("mt2032: rfin=%d lo1=%d lo1n=%d lo1a=%d sel=%d, lo1freq=%d\n",
141                   rfin,lo1,lo1n,lo1a,sel,lo1freq);
142
143         desired_lo2=lo1freq-rfin-if2;
144         lo2=(desired_lo2)/fref;
145         lo2n=lo2/8;
146         lo2a=lo2-(lo2n*8);
147         lo2num=((desired_lo2/1000)%(fref/1000))* 3780/(fref/1000); //scale to fit in 32bit arith
148         lo2freq=(lo2a+8*lo2n)*fref + lo2num*(fref/1000)/3780*1000;
149
150         tuner_dbg("mt2032: rfin=%d lo2=%d lo2n=%d lo2a=%d num=%d lo2freq=%d\n",
151                   rfin,lo2,lo2n,lo2a,lo2num,lo2freq);
152
153         if(lo1a<0 || lo1a>7 || lo1n<17 ||lo1n>48 || lo2a<0 ||lo2a >7 ||lo2n<17 || lo2n>30) {
154                 tuner_info("mt2032: frequency parameters out of range: %d %d %d %d\n",
155                            lo1a, lo1n, lo2a,lo2n);
156                 return(-1);
157         }
158
159         mt2032_spurcheck(fe, lo1freq, desired_lo2,  spectrum_from, spectrum_to);
160         // should recalculate lo1 (one step up/down)
161
162         // set up MT2032 register map for transfer over i2c
163         buf[0]=lo1n-1;
164         buf[1]=lo1a | (sel<<4);
165         buf[2]=0x86; // LOGC
166         buf[3]=0x0f; //reserved
167         buf[4]=0x1f;
168         buf[5]=(lo2n-1) | (lo2a<<5);
169         if(rfin >400*1000*1000)
170                 buf[6]=0xe4;
171         else
172                 buf[6]=0xf4; // set PKEN per rev 1.2
173         buf[7]=8+xogc;
174         buf[8]=0xc3; //reserved
175         buf[9]=0x4e; //reserved
176         buf[10]=0xec; //reserved
177         buf[11]=(lo2num&0xff);
178         buf[12]=(lo2num>>8) |0x80; // Lo2RST
179
180         return 0;
181 }
182
183 static int mt2032_check_lo_lock(struct dvb_frontend *fe)
184 {
185         struct microtune_priv *priv = fe->tuner_priv;
186         int try,lock=0;
187         unsigned char buf[2];
188
189         for(try=0;try<10;try++) {
190                 buf[0]=0x0e;
191                 tuner_i2c_xfer_send(&priv->i2c_props,buf,1);
192                 tuner_i2c_xfer_recv(&priv->i2c_props,buf,1);
193                 tuner_dbg("mt2032 Reg.E=0x%02x\n",buf[0]);
194                 lock=buf[0] &0x06;
195
196                 if (lock==6)
197                         break;
198
199                 tuner_dbg("mt2032: pll wait 1ms for lock (0x%2x)\n",buf[0]);
200                 udelay(1000);
201         }
202         return lock;
203 }
204
205 static int mt2032_optimize_vco(struct dvb_frontend *fe,int sel,int lock)
206 {
207         struct microtune_priv *priv = fe->tuner_priv;
208         unsigned char buf[2];
209         int tad1;
210
211         buf[0]=0x0f;
212         tuner_i2c_xfer_send(&priv->i2c_props,buf,1);
213         tuner_i2c_xfer_recv(&priv->i2c_props,buf,1);
214         tuner_dbg("mt2032 Reg.F=0x%02x\n",buf[0]);
215         tad1=buf[0]&0x07;
216
217         if(tad1 ==0) return lock;
218         if(tad1 ==1) return lock;
219
220         if(tad1==2) {
221                 if(sel==0)
222                         return lock;
223                 else sel--;
224         }
225         else {
226                 if(sel<4)
227                         sel++;
228                 else
229                         return lock;
230         }
231
232         tuner_dbg("mt2032 optimize_vco: sel=%d\n",sel);
233
234         buf[0]=0x0f;
235         buf[1]=sel;
236         tuner_i2c_xfer_send(&priv->i2c_props,buf,2);
237         lock=mt2032_check_lo_lock(fe);
238         return lock;
239 }
240
241
242 static void mt2032_set_if_freq(struct dvb_frontend *fe, unsigned int rfin,
243                                unsigned int if1, unsigned int if2,
244                                unsigned int from, unsigned int to)
245 {
246         unsigned char buf[21];
247         int lint_try,ret,sel,lock=0;
248         struct microtune_priv *priv = fe->tuner_priv;
249
250         tuner_dbg("mt2032_set_if_freq rfin=%d if1=%d if2=%d from=%d to=%d\n",
251                   rfin,if1,if2,from,to);
252
253         buf[0]=0;
254         ret=tuner_i2c_xfer_send(&priv->i2c_props,buf,1);
255         tuner_i2c_xfer_recv(&priv->i2c_props,buf,21);
256
257         buf[0]=0;
258         ret=mt2032_compute_freq(fe,rfin,if1,if2,from,to,&buf[1],&sel,priv->xogc);
259         if (ret<0)
260                 return;
261
262         // send only the relevant registers per Rev. 1.2
263         buf[0]=0;
264         ret=tuner_i2c_xfer_send(&priv->i2c_props,buf,4);
265         buf[5]=5;
266         ret=tuner_i2c_xfer_send(&priv->i2c_props,buf+5,4);
267         buf[11]=11;
268         ret=tuner_i2c_xfer_send(&priv->i2c_props,buf+11,3);
269         if(ret!=3)
270                 tuner_warn("i2c i/o error: rc == %d (should be 3)\n",ret);
271
272         // wait for PLLs to lock (per manual), retry LINT if not.
273         for(lint_try=0; lint_try<2; lint_try++) {
274                 lock=mt2032_check_lo_lock(fe);
275
276                 if(optimize_vco)
277                         lock=mt2032_optimize_vco(fe,sel,lock);
278                 if(lock==6) break;
279
280                 tuner_dbg("mt2032: re-init PLLs by LINT\n");
281                 buf[0]=7;
282                 buf[1]=0x80 +8+priv->xogc; // set LINT to re-init PLLs
283                 tuner_i2c_xfer_send(&priv->i2c_props,buf,2);
284                 mdelay(10);
285                 buf[1]=8+priv->xogc;
286                 tuner_i2c_xfer_send(&priv->i2c_props,buf,2);
287         }
288
289         if (lock!=6)
290                 tuner_warn("MT2032 Fatal Error: PLLs didn't lock.\n");
291
292         buf[0]=2;
293         buf[1]=0x20; // LOGC for optimal phase noise
294         ret=tuner_i2c_xfer_send(&priv->i2c_props,buf,2);
295         if (ret!=2)
296                 tuner_warn("i2c i/o error: rc == %d (should be 2)\n",ret);
297 }
298
299
300 static int mt2032_set_tv_freq(struct dvb_frontend *fe,
301                               struct analog_parameters *params)
302 {
303         int if2,from,to;
304
305         // signal bandwidth and picture carrier
306         if (params->std & V4L2_STD_525_60) {
307                 // NTSC
308                 from = 40750*1000;
309                 to   = 46750*1000;
310                 if2  = 45750*1000;
311         } else {
312                 // PAL
313                 from = 32900*1000;
314                 to   = 39900*1000;
315                 if2  = 38900*1000;
316         }
317
318         mt2032_set_if_freq(fe, params->frequency*62500,
319                            1090*1000*1000, if2, from, to);
320
321         return 0;
322 }
323
324 static int mt2032_set_radio_freq(struct dvb_frontend *fe,
325                                  struct analog_parameters *params)
326 {
327         struct microtune_priv *priv = fe->tuner_priv;
328         int if2;
329
330         if (params->std & V4L2_STD_525_60) {
331                 tuner_dbg("pinnacle ntsc\n");
332                 if2 = 41300 * 1000;
333         } else {
334                 tuner_dbg("pinnacle pal\n");
335                 if2 = 33300 * 1000;
336         }
337
338         // per Manual for FM tuning: first if center freq. 1085 MHz
339         mt2032_set_if_freq(fe, params->frequency * 125 / 2,
340                            1085*1000*1000,if2,if2,if2);
341
342         return 0;
343 }
344
345 static int mt2032_set_params(struct dvb_frontend *fe,
346                              struct analog_parameters *params)
347 {
348         struct microtune_priv *priv = fe->tuner_priv;
349         int ret = -EINVAL;
350
351         switch (params->mode) {
352         case V4L2_TUNER_RADIO:
353                 ret = mt2032_set_radio_freq(fe, params);
354                 priv->frequency = params->frequency * 125 / 2;
355                 break;
356         case V4L2_TUNER_ANALOG_TV:
357         case V4L2_TUNER_DIGITAL_TV:
358                 ret = mt2032_set_tv_freq(fe, params);
359                 priv->frequency = params->frequency * 62500;
360                 break;
361         }
362
363         return ret;
364 }
365
366 static struct dvb_tuner_ops mt2032_tuner_ops = {
367         .set_analog_params = mt2032_set_params,
368         .release           = microtune_release,
369         .get_frequency     = microtune_get_frequency,
370 };
371
372 // Initalization as described in "MT203x Programming Procedures", Rev 1.2, Feb.2001
373 static int mt2032_init(struct dvb_frontend *fe)
374 {
375         struct microtune_priv *priv = fe->tuner_priv;
376         unsigned char buf[21];
377         int ret,xogc,xok=0;
378
379         // Initialize Registers per spec.
380         buf[1]=2; // Index to register 2
381         buf[2]=0xff;
382         buf[3]=0x0f;
383         buf[4]=0x1f;
384         ret=tuner_i2c_xfer_send(&priv->i2c_props,buf+1,4);
385
386         buf[5]=6; // Index register 6
387         buf[6]=0xe4;
388         buf[7]=0x8f;
389         buf[8]=0xc3;
390         buf[9]=0x4e;
391         buf[10]=0xec;
392         ret=tuner_i2c_xfer_send(&priv->i2c_props,buf+5,6);
393
394         buf[12]=13;  // Index register 13
395         buf[13]=0x32;
396         ret=tuner_i2c_xfer_send(&priv->i2c_props,buf+12,2);
397
398         // Adjust XOGC (register 7), wait for XOK
399         xogc=7;
400         do {
401                 tuner_dbg("mt2032: xogc = 0x%02x\n",xogc&0x07);
402                 mdelay(10);
403                 buf[0]=0x0e;
404                 tuner_i2c_xfer_send(&priv->i2c_props,buf,1);
405                 tuner_i2c_xfer_recv(&priv->i2c_props,buf,1);
406                 xok=buf[0]&0x01;
407                 tuner_dbg("mt2032: xok = 0x%02x\n",xok);
408                 if (xok == 1) break;
409
410                 xogc--;
411                 tuner_dbg("mt2032: xogc = 0x%02x\n",xogc&0x07);
412                 if (xogc == 3) {
413                         xogc=4; // min. 4 per spec
414                         break;
415                 }
416                 buf[0]=0x07;
417                 buf[1]=0x88 + xogc;
418                 ret=tuner_i2c_xfer_send(&priv->i2c_props,buf,2);
419                 if (ret!=2)
420                         tuner_warn("i2c i/o error: rc == %d (should be 2)\n",ret);
421         } while (xok != 1 );
422         priv->xogc=xogc;
423
424         memcpy(&fe->ops.tuner_ops, &mt2032_tuner_ops, sizeof(struct dvb_tuner_ops));
425
426         return(1);
427 }
428
429 static void mt2050_set_antenna(struct dvb_frontend *fe, unsigned char antenna)
430 {
431         struct microtune_priv *priv = fe->tuner_priv;
432         unsigned char buf[2];
433         int ret;
434
435         buf[0] = 6;
436         buf[1] = antenna ? 0x11 : 0x10;
437         ret=tuner_i2c_xfer_send(&priv->i2c_props,buf,2);
438         tuner_dbg("mt2050: enabled antenna connector %d\n", antenna);
439 }
440
441 static void mt2050_set_if_freq(struct dvb_frontend *fe,unsigned int freq, unsigned int if2)
442 {
443         struct microtune_priv *priv = fe->tuner_priv;
444         unsigned int if1=1218*1000*1000;
445         unsigned int f_lo1,f_lo2,lo1,lo2,f_lo1_modulo,f_lo2_modulo,num1,num2,div1a,div1b,div2a,div2b;
446         int ret;
447         unsigned char buf[6];
448
449         tuner_dbg("mt2050_set_if_freq freq=%d if1=%d if2=%d\n",
450                   freq,if1,if2);
451
452         f_lo1=freq+if1;
453         f_lo1=(f_lo1/1000000)*1000000;
454
455         f_lo2=f_lo1-freq-if2;
456         f_lo2=(f_lo2/50000)*50000;
457
458         lo1=f_lo1/4000000;
459         lo2=f_lo2/4000000;
460
461         f_lo1_modulo= f_lo1-(lo1*4000000);
462         f_lo2_modulo= f_lo2-(lo2*4000000);
463
464         num1=4*f_lo1_modulo/4000000;
465         num2=4096*(f_lo2_modulo/1000)/4000;
466
467         // todo spurchecks
468
469         div1a=(lo1/12)-1;
470         div1b=lo1-(div1a+1)*12;
471
472         div2a=(lo2/8)-1;
473         div2b=lo2-(div2a+1)*8;
474
475         if (debug > 1) {
476                 tuner_dbg("lo1 lo2 = %d %d\n", lo1, lo2);
477                 tuner_dbg("num1 num2 div1a div1b div2a div2b= %x %x %x %x %x %x\n",
478                           num1,num2,div1a,div1b,div2a,div2b);
479         }
480
481         buf[0]=1;
482         buf[1]= 4*div1b + num1;
483         if(freq<275*1000*1000) buf[1] = buf[1]|0x80;
484
485         buf[2]=div1a;
486         buf[3]=32*div2b + num2/256;
487         buf[4]=num2-(num2/256)*256;
488         buf[5]=div2a;
489         if(num2!=0) buf[5]=buf[5]|0x40;
490
491         if (debug > 1) {
492                 int i;
493                 tuner_dbg("bufs is: ");
494                 for(i=0;i<6;i++)
495                         printk("%x ",buf[i]);
496                 printk("\n");
497         }
498
499         ret=tuner_i2c_xfer_send(&priv->i2c_props,buf,6);
500         if (ret!=6)
501                 tuner_warn("i2c i/o error: rc == %d (should be 6)\n",ret);
502 }
503
504 static int mt2050_set_tv_freq(struct dvb_frontend *fe,
505                               struct analog_parameters *params)
506 {
507         unsigned int if2;
508
509         if (params->std & V4L2_STD_525_60) {
510                 // NTSC
511                 if2 = 45750*1000;
512         } else {
513                 // PAL
514                 if2 = 38900*1000;
515         }
516         if (V4L2_TUNER_DIGITAL_TV == params->mode) {
517                 // DVB (pinnacle 300i)
518                 if2 = 36150*1000;
519         }
520         mt2050_set_if_freq(fe, params->frequency*62500, if2);
521         mt2050_set_antenna(fe, tv_antenna);
522
523         return 0;
524 }
525
526 static int mt2050_set_radio_freq(struct dvb_frontend *fe,
527                                  struct analog_parameters *params)
528 {
529         struct microtune_priv *priv = fe->tuner_priv;
530         int if2;
531
532         if (params->std & V4L2_STD_525_60) {
533                 tuner_dbg("pinnacle ntsc\n");
534                 if2 = 41300 * 1000;
535         } else {
536                 tuner_dbg("pinnacle pal\n");
537                 if2 = 33300 * 1000;
538         }
539
540         mt2050_set_if_freq(fe, params->frequency * 125 / 2, if2);
541         mt2050_set_antenna(fe, radio_antenna);
542
543         return 0;
544 }
545
546 static int mt2050_set_params(struct dvb_frontend *fe,
547                              struct analog_parameters *params)
548 {
549         struct microtune_priv *priv = fe->tuner_priv;
550         int ret = -EINVAL;
551
552         switch (params->mode) {
553         case V4L2_TUNER_RADIO:
554                 ret = mt2050_set_radio_freq(fe, params);
555                 priv->frequency = params->frequency * 125 / 2;
556                 break;
557         case V4L2_TUNER_ANALOG_TV:
558         case V4L2_TUNER_DIGITAL_TV:
559                 ret = mt2050_set_tv_freq(fe, params);
560                 priv->frequency = params->frequency * 62500;
561                 break;
562         }
563
564         return ret;
565 }
566
567 static struct dvb_tuner_ops mt2050_tuner_ops = {
568         .set_analog_params = mt2050_set_params,
569         .release           = microtune_release,
570         .get_frequency     = microtune_get_frequency,
571 };
572
573 static int mt2050_init(struct dvb_frontend *fe)
574 {
575         struct microtune_priv *priv = fe->tuner_priv;
576         unsigned char buf[2];
577         int ret;
578
579         buf[0]=6;
580         buf[1]=0x10;
581         ret=tuner_i2c_xfer_send(&priv->i2c_props,buf,2); //  power
582
583         buf[0]=0x0f;
584         buf[1]=0x0f;
585         ret=tuner_i2c_xfer_send(&priv->i2c_props,buf,2); // m1lo
586
587         buf[0]=0x0d;
588         ret=tuner_i2c_xfer_send(&priv->i2c_props,buf,1);
589         tuner_i2c_xfer_recv(&priv->i2c_props,buf,1);
590
591         tuner_dbg("mt2050: sro is %x\n",buf[0]);
592
593         memcpy(&fe->ops.tuner_ops, &mt2050_tuner_ops, sizeof(struct dvb_tuner_ops));
594
595         return 0;
596 }
597
598 struct dvb_frontend *microtune_attach(struct dvb_frontend *fe,
599                                       struct i2c_adapter* i2c_adap,
600                                       u8 i2c_addr)
601 {
602         struct microtune_priv *priv = NULL;
603         char *name;
604         unsigned char buf[21];
605         int company_code;
606
607         priv = kzalloc(sizeof(struct microtune_priv), GFP_KERNEL);
608         if (priv == NULL)
609                 return NULL;
610         fe->tuner_priv = priv;
611
612         priv->i2c_props.addr = i2c_addr;
613         priv->i2c_props.adap = i2c_adap;
614
615         //priv->radio_if2 = 10700 * 1000;       /* 10.7MHz - FM radio */
616
617         memset(buf,0,sizeof(buf));
618
619         name = "unknown";
620
621         tuner_i2c_xfer_send(&priv->i2c_props,buf,1);
622         tuner_i2c_xfer_recv(&priv->i2c_props,buf,21);
623         if (debug) {
624                 int i;
625                 tuner_dbg("MT20xx hexdump:");
626                 for(i=0;i<21;i++) {
627                         printk(" %02x",buf[i]);
628                         if(((i+1)%8)==0) printk(" ");
629                 }
630                 printk("\n");
631         }
632         company_code = buf[0x11] << 8 | buf[0x12];
633         tuner_info("microtune: companycode=%04x part=%02x rev=%02x\n",
634                    company_code,buf[0x13],buf[0x14]);
635
636
637         if (buf[0x13] < ARRAY_SIZE(microtune_part) &&
638             NULL != microtune_part[buf[0x13]])
639                 name = microtune_part[buf[0x13]];
640         switch (buf[0x13]) {
641         case MT2032:
642                 mt2032_init(fe);
643                 break;
644         case MT2050:
645                 mt2050_init(fe);
646                 break;
647         default:
648                 tuner_info("microtune %s found, not (yet?) supported, sorry :-/\n",
649                            name);
650                 return 0;
651         }
652
653         strlcpy(fe->ops.tuner_ops.info.name, name,
654                 sizeof(fe->ops.tuner_ops.info.name));
655         tuner_info("microtune %s found, OK\n",name);
656         return fe;
657 }
658
659 EXPORT_SYMBOL_GPL(microtune_attach);
660
661 MODULE_DESCRIPTION("Microtune tuner driver");
662 MODULE_AUTHOR("Ralph Metzler, Gerd Knorr, Gunther Mayer");
663 MODULE_LICENSE("GPL");
664
665 /*
666  * Overrides for Emacs so that we follow Linus's tabbing style.
667  * ---------------------------------------------------------------------------
668  * Local variables:
669  * c-basic-offset: 8
670  * End:
671  */