1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
|
/*
* Copyright (C) 2009 ST-Ericsson SA
* Copyright (C) 2009 STMicroelectronics
*
* I2C master mode controller driver, used in Nomadik 8815
* and Ux500 platforms.
*
* Author: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
* Author: Sachin Verma <sachin.verma@st.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2, as
* published by the Free Software Foundation.
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/amba/bus.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/i2c.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/pm_runtime.h>
#include <linux/of.h>
#include <linux/pinctrl/consumer.h>
#define DRIVER_NAME "nmk-i2c"
/* I2C Controller register offsets */
#define I2C_CR (0x000)
#define I2C_SCR (0x004)
#define I2C_HSMCR (0x008)
#define I2C_MCR (0x00C)
#define I2C_TFR (0x010)
#define I2C_SR (0x014)
#define I2C_RFR (0x018)
#define I2C_TFTR (0x01C)
#define I2C_RFTR (0x020)
#define I2C_DMAR (0x024)
#define I2C_BRCR (0x028)
#define I2C_IMSCR (0x02C)
#define I2C_RISR (0x030)
#define I2C_MISR (0x034)
#define I2C_ICR (0x038)
/* Control registers */
#define I2C_CR_PE (0x1 << 0) /* Peripheral Enable */
#define I2C_CR_OM (0x3 << 1) /* Operating mode */
#define I2C_CR_SAM (0x1 << 3) /* Slave addressing mode */
#define I2C_CR_SM (0x3 << 4) /* Speed mode */
#define I2C_CR_SGCM (0x1 << 6) /* Slave general call mode */
#define I2C_CR_FTX (0x1 << 7) /* Flush Transmit */
#define I2C_CR_FRX (0x1 << 8) /* Flush Receive */
#define I2C_CR_DMA_TX_EN (0x1 << 9) /* DMA Tx enable */
#define I2C_CR_DMA_RX_EN (0x1 << 10) /* DMA Rx Enable */
#define I2C_CR_DMA_SLE (0x1 << 11) /* DMA sync. logic enable */
#define I2C_CR_LM (0x1 << 12) /* Loopback mode */
#define I2C_CR_FON (0x3 << 13) /* Filtering on */
#define I2C_CR_FS (0x3 << 15) /* Force stop enable */
/* Master controller (MCR) register */
#define I2C_MCR_OP (0x1 << 0) /* Operation */
#define I2C_MCR_A7 (0x7f << 1) /* 7-bit address */
#define I2C_MCR_EA10 (0x7 << 8) /* 10-bit Extended address */
#define I2C_MCR_SB (0x1 << 11) /* Extended address */
#define I2C_MCR_AM (0x3 << 12) /* Address type */
#define I2C_MCR_STOP (0x1 << 14) /* Stop condition */
#define I2C_MCR_LENGTH (0x7ff << 15) /* Transaction length */
/* Status register (SR) */
#define I2C_SR_OP (0x3 << 0) /* Operation */
#define I2C_SR_STATUS (0x3 << 2) /* controller status */
#define I2C_SR_CAUSE (0x7 << 4) /* Abort cause */
#define I2C_SR_TYPE (0x3 << 7) /* Receive type */
#define I2C_SR_LENGTH (0x7ff << 9) /* Transfer length */
/* Interrupt mask set/clear (IMSCR) bits */
#define I2C_IT_TXFE (0x1 << 0)
#define I2C_IT_TXFNE (0x1 << 1)
#define I2C_IT_TXFF (0x1 << 2)
#define I2C_IT_TXFOVR (0x1 << 3)
#define I2C_IT_RXFE (0x1 << 4)
#define I2C_IT_RXFNF (0x1 << 5)
#define I2C_IT_RXFF (0x1 << 6)
#define I2C_IT_RFSR (0x1 << 16)
#define I2C_IT_RFSE (0x1 << 17)
#define I2C_IT_WTSR (0x1 << 18)
#define I2C_IT_MTD (0x1 << 19)
#define I2C_IT_STD (0x1 << 20)
#define I2C_IT_MAL (0x1 << 24)
#define I2C_IT_BERR (0x1 << 25)
#define I2C_IT_MTDWS (0x1 << 28)
#define GEN_MASK(val, mask, sb) (((val) << (sb)) & (mask))
/* some bits in ICR are reserved */
#define I2C_CLEAR_ALL_INTS 0x131f007f
/* first three msb bits are reserved */
#define IRQ_MASK(mask) (mask & 0x1fffffff)
/* maximum threshold value */
#define MAX_I2C_FIFO_THRESHOLD 15
enum i2c_freq_mode {
I2C_FREQ_MODE_STANDARD, /* up to 100 Kb/s */
I2C_FREQ_MODE_FAST, /* up to 400 Kb/s */
I2C_FREQ_MODE_HIGH_SPEED, /* up to 3.4 Mb/s */
I2C_FREQ_MODE_FAST_PLUS, /* up to 1 Mb/s */
};
/**
* struct i2c_vendor_data - per-vendor variations
* @has_mtdws: variant has the MTDWS bit
* @fifodepth: variant FIFO depth
*/
struct i2c_vendor_data {
bool has_mtdws;
u32 fifodepth;
};
enum i2c_status {
I2C_NOP,
I2C_ON_GOING,
I2C_OK,
I2C_ABORT
};
/* operation */
enum i2c_operation {
I2C_NO_OPERATION = 0xff,
I2C_WRITE = 0x00,
I2C_READ = 0x01
};
/**
* struct i2c_nmk_client - client specific data
* @slave_adr: 7-bit slave address
* @count: no. bytes to be transferred
* @buffer: client data buffer
* @xfer_bytes: bytes transferred till now
* @operation: current I2C operation
*/
struct i2c_nmk_client {
unsigned short slave_adr;
unsigned long count;
unsigned char *buffer;
unsigned long xfer_bytes;
enum i2c_operation operation;
};
/**
* struct nmk_i2c_dev - private data structure of the controller.
* @vendor: vendor data for this variant.
* @adev: parent amba device.
* @adap: corresponding I2C adapter.
* @irq: interrupt line for the controller.
* @virtbase: virtual io memory area.
* @clk: hardware i2c block clock.
* @cli: holder of client specific data.
* @clk_freq: clock frequency for the operation mode
* @tft: Tx FIFO Threshold in bytes
* @rft: Rx FIFO Threshold in bytes
* @timeout Slave response timeout (ms)
* @sm: speed mode
* @stop: stop condition.
* @xfer_complete: acknowledge completion for a I2C message.
* @result: controller propogated result.
*/
struct nmk_i2c_dev {
struct i2c_vendor_data *vendor;
struct amba_device *adev;
struct i2c_adapter adap;
int irq;
void __iomem *virtbase;
struct clk *clk;
struct i2c_nmk_client cli;
u32 clk_freq;
unsigned char tft;
unsigned char rft;
int timeout;
enum i2c_freq_mode sm;
int stop;
struct completion xfer_complete;
int result;
};
/* controller's abort causes */
static const char *abort_causes[] = {
"no ack received after address transmission",
"no ack received during data phase",
"ack received after xmission of master code",
"master lost arbitration",
"slave restarts",
"slave reset",
"overflow, maxsize is 2047 bytes",
};
static inline void i2c_set_bit(void __iomem *reg, u32 mask)
{
writel(readl(reg) | mask, reg);
}
static inline void i2c_clr_bit(void __iomem *reg, u32 mask)
{
writel(readl(reg) & ~mask, reg);
}
/**
* flush_i2c_fifo() - This function flushes the I2C FIFO
* @dev: private data of I2C Driver
*
* This function flushes the I2C Tx and Rx FIFOs. It returns
* 0 on successful flushing of FIFO
*/
static int flush_i2c_fifo(struct nmk_i2c_dev *dev)
{
#define LOOP_ATTEMPTS 10
int i;
unsigned long timeout;
/*
* flush the transmit and receive FIFO. The flushing
* operation takes several cycles before to be completed.
* On the completion, the I2C internal logic clears these
* bits, until then no one must access Tx, Rx FIFO and
* should poll on these bits waiting for the completion.
*/
writel((I2C_CR_FTX | I2C_CR_FRX), dev->virtbase + I2C_CR);
for (i = 0; i < LOOP_ATTEMPTS; i++) {
timeout = jiffies + dev->adap.timeout;
while (!time_after(jiffies, timeout)) {
if ((readl(dev->virtbase + I2C_CR) &
(I2C_CR_FTX | I2C_CR_FRX)) == 0)
return 0;
}
}
dev_err(&dev->adev->dev,
"flushing operation timed out giving up after %d attempts",
LOOP_ATTEMPTS);
return -ETIMEDOUT;
}
/**
* disable_all_interrupts() - Disable all interrupts of this I2c Bus
* @dev: private data of I2C Driver
*/
static void disable_all_interrupts(struct nmk_i2c_dev *dev)
{
u32 mask = IRQ_MASK(0);
writel(mask, dev->virtbase + I2C_IMSCR);
}
/**
* clear_all_interrupts() - Clear all interrupts of I2C Controller
* @dev: private data of I2C Driver
*/
static void clear_all_interrupts(struct nmk_i2c_dev *dev)
{
u32 mask;
mask = IRQ_MASK(I2C_CLEAR_ALL_INTS);
writel(mask, dev->virtbase + I2C_ICR);
}
/**
* init_hw() - initialize the I2C hardware
* @dev: private data of I2C Driver
*/
static int init_hw(struct nmk_i2c_dev *dev)
{
int stat;
stat = flush_i2c_fifo(dev);
if (stat)
goto exit;
/* disable the controller */
i2c_clr_bit(dev->virtbase + I2C_CR , I2C_CR_PE);
disable_all_interrupts(dev);
clear_all_interrupts(dev);
dev->cli.operation = I2C_NO_OPERATION;
exit:
return stat;
}
/* enable peripheral, master mode operation */
#define DEFAULT_I2C_REG_CR ((1 << 1) | I2C_CR_PE)
/**
* load_i2c_mcr_reg() - load the MCR register
* @dev: private data of controller
* @flags: message flags
*/
static u32 load_i2c_mcr_reg(struct nmk_i2c_dev *dev, u16 flags)
{
u32 mcr = 0;
unsigned short slave_adr_3msb_bits;
mcr |= GEN_MASK(dev->cli.slave_adr, I2C_MCR_A7, 1);
if (unlikely(flags & I2C_M_TEN)) {
/* 10-bit address transaction */
mcr |= GEN_MASK(2, I2C_MCR_AM, 12);
/*
* Get the top 3 bits.
* EA10 represents extended address in MCR. This includes
* the extension (MSB bits) of the 7 bit address loaded
* in A7
*/
slave_adr_3msb_bits = (dev->cli.slave_adr >> 7) & 0x7;
mcr |= GEN_MASK(slave_adr_3msb_bits, I2C_MCR_EA10, 8);
} else {
/* 7-bit address transaction */
mcr |= GEN_MASK(1, I2C_MCR_AM, 12);
}
/* start byte procedure not applied */
mcr |= GEN_MASK(0, I2C_MCR_SB, 11);
/* check the operation, master read/write? */
if (dev->cli.operation == I2C_WRITE)
mcr |= GEN_MASK(I2C_WRITE, I2C_MCR_OP, 0);
else
mcr |= GEN_MASK(I2C_READ, I2C_MCR_OP, 0);
/* stop or repeated start? */
if (dev->stop)
mcr |= GEN_MASK(1, I2C_MCR_STOP, 14);
else
mcr &= ~(GEN_MASK(1, I2C_MCR_STOP, 14));
mcr |= GEN_MASK(dev->cli.count, I2C_MCR_LENGTH, 15);
return mcr;
}
/**
* setup_i2c_controller() - setup the controller
* @dev: private data of controller
*/
static void setup_i2c_controller(struct nmk_i2c_dev *dev)
{
u32 brcr1, brcr2;
u32 i2c_clk, div;
u32 ns;
u16 slsu;
writel(0x0, dev->virtbase + I2C_CR);
writel(0x0, dev->virtbase + I2C_HSMCR);
writel(0x0, dev->virtbase + I2C_TFTR);
writel(0x0, dev->virtbase + I2C_RFTR);
writel(0x0, dev->virtbase + I2C_DMAR);
i2c_clk = clk_get_rate(dev->clk);
/*
* set the slsu:
*
* slsu defines the data setup time after SCL clock
* stretching in terms of i2c clk cycles + 1 (zero means
* "wait one cycle"), the needed setup time for the three
* modes are 250ns, 100ns, 10ns respectively.
*
* As the time for one cycle T in nanoseconds is
* T = (1/f) * 1000000000 =>
* slsu = cycles / (1000000000 / f) + 1
*/
ns = DIV_ROUND_UP_ULL(1000000000ULL, i2c_clk);
switch (dev->sm) {
case I2C_FREQ_MODE_FAST:
case I2C_FREQ_MODE_FAST_PLUS:
slsu = DIV_ROUND_UP(100, ns); /* Fast */
break;
case I2C_FREQ_MODE_HIGH_SPEED:
slsu = DIV_ROUND_UP(10, ns); /* High */
break;
case I2C_FREQ_MODE_STANDARD:
default:
slsu = DIV_ROUND_UP(250, ns); /* Standard */
break;
}
slsu += 1;
dev_dbg(&dev->adev->dev, "calculated SLSU = %04x\n", slsu);
writel(slsu << 16, dev->virtbase + I2C_SCR);
/*
* The spec says, in case of std. mode the divider is
* 2 whereas it is 3 for fast and fastplus mode of
* operation. TODO - high speed support.
*/
div = (dev->clk_freq > 100000) ? 3 : 2;
/*
* generate the mask for baud rate counters. The controller
* has two baud rate counters. One is used for High speed
* operation, and the other is for std, fast mode, fast mode
* plus operation. Currently we do not supprt high speed mode
* so set brcr1 to 0.
*/
brcr1 = 0 << 16;
brcr2 = (i2c_clk/(dev->clk_freq * div)) & 0xffff;
/* set the baud rate counter register */
writel((brcr1 | brcr2), dev->virtbase + I2C_BRCR);
/*
* set the speed mode. Currently we support
* only standard and fast mode of operation
* TODO - support for fast mode plus (up to 1Mb/s)
* and high speed (up to 3.4 Mb/s)
*/
if (dev->sm > I2C_FREQ_MODE_FAST) {
dev_err(&dev->adev->dev,
"do not support this mode defaulting to std. mode\n");
brcr2 = i2c_clk/(100000 * 2) & 0xffff;
writel((brcr1 | brcr2), dev->virtbase + I2C_BRCR);
writel(I2C_FREQ_MODE_STANDARD << 4,
dev->virtbase + I2C_CR);
}
writel(dev->sm << 4, dev->virtbase + I2C_CR);
/* set the Tx and Rx FIFO threshold */
writel(dev->tft, dev->virtbase + I2C_TFTR);
writel(dev->rft, dev->virtbase + I2C_RFTR);
}
/**
* read_i2c() - Read from I2C client device
* @dev: private data of I2C Driver
* @flags: message flags
*
* This function reads from i2c client device when controller is in
* master mode. There is a completion timeout. If there is no transfer
* before timeout error is returned.
*/
static int read_i2c(struct nmk_i2c_dev *dev, u16 flags)
{
u32 status = 0;
u32 mcr, irq_mask;
int timeout;
mcr = load_i2c_mcr_reg(dev, flags);
writel(mcr, dev->virtbase + I2C_MCR);
/* load the current CR value */
writel(readl(dev->virtbase + I2C_CR) | DEFAULT_I2C_REG_CR,
dev->virtbase + I2C_CR);
/* enable the controller */
i2c_set_bit(dev->virtbase + I2C_CR, I2C_CR_PE);
init_completion(&dev->xfer_complete);
/* enable interrupts by setting the mask */
irq_mask = (I2C_IT_RXFNF | I2C_IT_RXFF |
I2C_IT_MAL | I2C_IT_BERR);
if (dev->stop || !dev->vendor->has_mtdws)
irq_mask |= I2C_IT_MTD;
else
irq_mask |= I2C_IT_MTDWS;
irq_mask = I2C_CLEAR_ALL_INTS & IRQ_MASK(irq_mask);
writel(readl(dev->virtbase + I2C_IMSCR) | irq_mask,
dev->virtbase + I2C_IMSCR);
timeout = wait_for_completion_timeout(
&dev->xfer_complete, dev->adap.timeout);
if (timeout == 0) {
/* Controller timed out */
dev_err(&dev->adev->dev, "read from slave 0x%x timed out\n",
dev->cli.slave_adr);
status = -ETIMEDOUT;
}
return status;
}
static void fill_tx_fifo(struct nmk_i2c_dev *dev, int no_bytes)
{
int count;
for (count = (no_bytes - 2);
(count > 0) &&
(dev->cli.count != 0);
count--) {
/* write to the Tx FIFO */
writeb(*dev->cli.buffer,
dev->virtbase + I2C_TFR);
dev->cli.buffer++;
dev->cli.count--;
dev->cli.xfer_bytes++;
}
}
/**
* write_i2c() - Write data to I2C client.
* @dev: private data of I2C Driver
* @flags: message flags
*
* This function writes data to I2C client
*/
static int write_i2c(struct nmk_i2c_dev *dev, u16 flags)
{
u32 status = 0;
u32 mcr, irq_mask;
int timeout;
mcr = load_i2c_mcr_reg(dev, flags);
writel(mcr, dev->virtbase + I2C_MCR);
/* load the current CR value */
writel(readl(dev->virtbase + I2C_CR) | DEFAULT_I2C_REG_CR,
dev->virtbase + I2C_CR);
/* enable the controller */
i2c_set_bit(dev->virtbase + I2C_CR , I2C_CR_PE);
init_completion(&dev->xfer_complete);
/* enable interrupts by settings the masks */
irq_mask = (I2C_IT_TXFOVR | I2C_IT_MAL | I2C_IT_BERR);
/* Fill the TX FIFO with transmit data */
fill_tx_fifo(dev, MAX_I2C_FIFO_THRESHOLD);
if (dev->cli.count != 0)
irq_mask |= I2C_IT_TXFNE;
/*
* check if we want to transfer a single or multiple bytes, if so
* set the MTDWS bit (Master Transaction Done Without Stop)
* to start repeated start operation
*/
if (dev->stop || !dev->vendor->has_mtdws)
irq_mask |= I2C_IT_MTD;
else
irq_mask |= I2C_IT_MTDWS;
irq_mask = I2C_CLEAR_ALL_INTS & IRQ_MASK(irq_mask);
writel(readl(dev->virtbase + I2C_IMSCR) | irq_mask,
dev->virtbase + I2C_IMSCR);
timeout = wait_for_completion_timeout(
&dev->xfer_complete, dev->adap.timeout);
if (timeout == 0) {
/* Controller timed out */
dev_err(&dev->adev->dev, "write to slave 0x%x timed out\n",
dev->cli.slave_adr);
status = -ETIMEDOUT;
}
return status;
}
/**
* nmk_i2c_xfer_one() - transmit a single I2C message
* @dev: device with a message encoded into it
* @flags: message flags
*/
static int nmk_i2c_xfer_one(struct nmk_i2c_dev *dev, u16 flags)
{
int status;
if (flags & I2C_M_RD) {
/* read operation */
dev->cli.operation = I2C_READ;
status = read_i2c(dev, flags);
} else {
/* write operation */
dev->cli.operation = I2C_WRITE;
status = write_i2c(dev, flags);
}
if (status || (dev->result)) {
u32 i2c_sr;
u32 cause;
i2c_sr = readl(dev->virtbase + I2C_SR);
/*
* Check if the controller I2C operation status
* is set to ABORT(11b).
*/
if (((i2c_sr >> 2) & 0x3) == 0x3) {
/* get the abort cause */
cause = (i2c_sr >> 4) & 0x7;
dev_err(&dev->adev->dev, "%s\n",
cause >= ARRAY_SIZE(abort_causes) ?
"unknown reason" :
abort_causes[cause]);
}
(void) init_hw(dev);
status = status ? status : dev->result;
}
return status;
}
/**
* nmk_i2c_xfer() - I2C transfer function used by kernel framework
* @i2c_adap: Adapter pointer to the controller
* @msgs: Pointer to data to be written.
* @num_msgs: Number of messages to be executed
*
* This is the function called by the generic kernel i2c_transfer()
* or i2c_smbus...() API calls. Note that this code is protected by the
* semaphore set in the kernel i2c_transfer() function.
*
* NOTE:
* READ TRANSFER : We impose a restriction of the first message to be the
* index message for any read transaction.
* - a no index is coded as '0',
* - 2byte big endian index is coded as '3'
* !!! msg[0].buf holds the actual index.
* This is compatible with generic messages of smbus emulator
* that send a one byte index.
* eg. a I2C transation to read 2 bytes from index 0
* idx = 0;
* msg[0].addr = client->addr;
* msg[0].flags = 0x0;
* msg[0].len = 1;
* msg[0].buf = &idx;
*
* msg[1].addr = client->addr;
* msg[1].flags = I2C_M_RD;
* msg[1].len = 2;
* msg[1].buf = rd_buff
* i2c_transfer(adap, msg, 2);
*
* WRITE TRANSFER : The I2C standard interface interprets all data as payload.
* If you want to emulate an SMBUS write transaction put the
* index as first byte(or first and second) in the payload.
* eg. a I2C transation to write 2 bytes from index 1
* wr_buff[0] = 0x1;
* wr_buff[1] = 0x23;
* wr_buff[2] = 0x46;
* msg[0].flags = 0x0;
* msg[0].len = 3;
* msg[0].buf = wr_buff;
* i2c_transfer(adap, msg, 1);
*
* To read or write a block of data (multiple bytes) using SMBUS emulation
* please use the i2c_smbus_read_i2c_block_data()
* or i2c_smbus_write_i2c_block_data() API
*/
static int nmk_i2c_xfer(struct i2c_adapter *i2c_adap,
struct i2c_msg msgs[], int num_msgs)
{
int status = 0;
int i;
struct nmk_i2c_dev *dev = i2c_get_adapdata(i2c_adap);
int j;
pm_runtime_get_sync(&dev->adev->dev);
/* Attempt three times to send the message queue */
for (j = 0; j < 3; j++) {
/* setup the i2c controller */
setup_i2c_controller(dev);
for (i = 0; i < num_msgs; i++) {
dev->cli.slave_adr = msgs[i].addr;
dev->cli.buffer = msgs[i].buf;
dev->cli.count = msgs[i].len;
dev->stop = (i < (num_msgs - 1)) ? 0 : 1;
dev->result = 0;
status = nmk_i2c_xfer_one(dev, msgs[i].flags);
if (status != 0)
break;
}
if (status == 0)
break;
}
pm_runtime_put_sync(&dev->adev->dev);
/* return the no. messages processed */
if (status)
return status;
else
return num_msgs;
}
/**
* disable_interrupts() - disable the interrupts
* @dev: private data of controller
* @irq: interrupt number
*/
static int disable_interrupts(struct nmk_i2c_dev *dev, u32 irq)
{
irq = IRQ_MASK(irq);
writel(readl(dev->virtbase + I2C_IMSCR) & ~(I2C_CLEAR_ALL_INTS & irq),
dev->virtbase + I2C_IMSCR);
return 0;
}
/**
* i2c_irq_handler() - interrupt routine
* @irq: interrupt number
* @arg: data passed to the handler
*
* This is the interrupt handler for the i2c driver. Currently
* it handles the major interrupts like Rx & Tx FIFO management
* interrupts, master transaction interrupts, arbitration and
* bus error interrupts. The rest of the interrupts are treated as
* unhandled.
*/
static irqreturn_t i2c_irq_handler(int irq, void *arg)
{
struct nmk_i2c_dev *dev = arg;
u32 tft, rft;
u32 count;
u32 misr, src;
/* load Tx FIFO and Rx FIFO threshold values */
tft = readl(dev->virtbase + I2C_TFTR);
rft = readl(dev->virtbase + I2C_RFTR);
/* read interrupt status register */
misr = readl(dev->virtbase + I2C_MISR);
src = __ffs(misr);
switch ((1 << src)) {
/* Transmit FIFO nearly empty interrupt */
case I2C_IT_TXFNE:
{
if (dev->cli.operation == I2C_READ) {
/*
* in read operation why do we care for writing?
* so disable the Transmit FIFO interrupt
*/
disable_interrupts(dev, I2C_IT_TXFNE);
} else {
fill_tx_fifo(dev, (MAX_I2C_FIFO_THRESHOLD - tft));
/*
* if done, close the transfer by disabling the
* corresponding TXFNE interrupt
*/
if (dev->cli.count == 0)
disable_interrupts(dev, I2C_IT_TXFNE);
}
}
break;
/*
* Rx FIFO nearly full interrupt.
* This is set when the numer of entries in Rx FIFO is
* greater or equal than the threshold value programmed
* in RFT
*/
case I2C_IT_RXFNF:
for (count = rft; count > 0; count--) {
/* Read the Rx FIFO */
*dev->cli.buffer = readb(dev->virtbase + I2C_RFR);
dev->cli.buffer++;
}
dev->cli.count -= rft;
dev->cli.xfer_bytes += rft;
break;
/* Rx FIFO full */
case I2C_IT_RXFF:
for (count = MAX_I2C_FIFO_THRESHOLD; count > 0; count--) {
*dev->cli.buffer = readb(dev->virtbase + I2C_RFR);
dev->cli.buffer++;
}
dev->cli.count -= MAX_I2C_FIFO_THRESHOLD;
dev->cli.xfer_bytes += MAX_I2C_FIFO_THRESHOLD;
break;
/* Master Transaction Done with/without stop */
case I2C_IT_MTD:
case I2C_IT_MTDWS:
if (dev->cli.operation == I2C_READ) {
while (!(readl(dev->virtbase + I2C_RISR)
& I2C_IT_RXFE)) {
if (dev->cli.count == 0)
break;
*dev->cli.buffer =
readb(dev->virtbase + I2C_RFR);
dev->cli.buffer++;
dev->cli.count--;
dev->cli.xfer_bytes++;
}
}
disable_all_interrupts(dev);
clear_all_interrupts(dev);
if (dev->cli.count) {
dev->result = -EIO;
dev_err(&dev->adev->dev,
"%lu bytes still remain to be xfered\n",
dev->cli.count);
(void) init_hw(dev);
}
complete(&dev->xfer_complete);
break;
/* Master Arbitration lost interrupt */
case I2C_IT_MAL:
dev->result = -EIO;
(void) init_hw(dev);
i2c_set_bit(dev->virtbase + I2C_ICR, I2C_IT_MAL);
complete(&dev->xfer_complete);
break;
/*
* Bus Error interrupt.
* This happens when an unexpected start/stop condition occurs
* during the transaction.
*/
case I2C_IT_BERR:
dev->result = -EIO;
/* get the status */
if (((readl(dev->virtbase + I2C_SR) >> 2) & 0x3) == I2C_ABORT)
(void) init_hw(dev);
i2c_set_bit(dev->virtbase + I2C_ICR, I2C_IT_BERR);
complete(&dev->xfer_complete);
break;
/*
* Tx FIFO overrun interrupt.
* This is set when a write operation in Tx FIFO is performed and
* the Tx FIFO is full.
*/
case I2C_IT_TXFOVR:
dev->result = -EIO;
(void) init_hw(dev);
dev_err(&dev->adev->dev, "Tx Fifo Over run\n");
complete(&dev->xfer_complete);
break;
/* unhandled interrupts by this driver - TODO*/
case I2C_IT_TXFE:
case I2C_IT_TXFF:
case I2C_IT_RXFE:
case I2C_IT_RFSR:
case I2C_IT_RFSE:
case I2C_IT_WTSR:
case I2C_IT_STD:
dev_err(&dev->adev->dev, "unhandled Interrupt\n");
break;
default:
dev_err(&dev->adev->dev, "spurious Interrupt..\n");
break;
}
return IRQ_HANDLED;
}
#ifdef CONFIG_PM_SLEEP
static int nmk_i2c_suspend_late(struct device *dev)
{
pinctrl_pm_select_sleep_state(dev);
return 0;
}
static int nmk_i2c_resume_early(struct device *dev)
{
/* First go to the default state */
pinctrl_pm_select_default_state(dev);
/* Then let's idle the pins until the next transfer happens */
pinctrl_pm_select_idle_state(dev);
return 0;
}
#endif
#ifdef CONFIG_PM
static int nmk_i2c_runtime_suspend(struct device *dev)
{
struct amba_device *adev = to_amba_device(dev);
struct nmk_i2c_dev *nmk_i2c = amba_get_drvdata(adev);
clk_disable_unprepare(nmk_i2c->clk);
pinctrl_pm_select_idle_state(dev);
return 0;
}
static int nmk_i2c_runtime_resume(struct device *dev)
{
struct amba_device *adev = to_amba_device(dev);
struct nmk_i2c_dev *nmk_i2c = amba_get_drvdata(adev);
int ret;
ret = clk_prepare_enable(nmk_i2c->clk);
if (ret) {
dev_err(dev, "can't prepare_enable clock\n");
return ret;
}
pinctrl_pm_select_default_state(dev);
ret = init_hw(nmk_i2c);
if (ret) {
clk_disable_unprepare(nmk_i2c->clk);
pinctrl_pm_select_idle_state(dev);
}
return ret;
}
#endif
static const struct dev_pm_ops nmk_i2c_pm = {
SET_LATE_SYSTEM_SLEEP_PM_OPS(nmk_i2c_suspend_late, nmk_i2c_resume_early)
SET_PM_RUNTIME_PM_OPS(nmk_i2c_runtime_suspend,
nmk_i2c_runtime_resume,
NULL)
};
static unsigned int nmk_i2c_functionality(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR;
}
static const struct i2c_algorithm nmk_i2c_algo = {
.master_xfer = nmk_i2c_xfer,
.functionality = nmk_i2c_functionality
};
static void nmk_i2c_of_probe(struct device_node *np,
struct nmk_i2c_dev *nmk)
{
/* Default to 100 kHz if no frequency is given in the node */
if (of_property_read_u32(np, "clock-frequency", &nmk->clk_freq))
nmk->clk_freq = 100000;
/* This driver only supports 'standard' and 'fast' modes of operation. */
if (nmk->clk_freq <= 100000)
nmk->sm = I2C_FREQ_MODE_STANDARD;
else
nmk->sm = I2C_FREQ_MODE_FAST;
nmk->tft = 1; /* Tx FIFO threshold */
nmk->rft = 8; /* Rx FIFO threshold */
nmk->timeout = 200; /* Slave response timeout(ms) */
}
static int nmk_i2c_probe(struct amba_device *adev, const struct amba_id *id)
{
int ret = 0;
struct device_node *np = adev->dev.of_node;
struct nmk_i2c_dev *dev;
struct i2c_adapter *adap;
struct i2c_vendor_data *vendor = id->data;
u32 max_fifo_threshold = (vendor->fifodepth / 2) - 1;
dev = devm_kzalloc(&adev->dev, sizeof(struct nmk_i2c_dev), GFP_KERNEL);
if (!dev) {
dev_err(&adev->dev, "cannot allocate memory\n");
ret = -ENOMEM;
goto err_no_mem;
}
dev->vendor = vendor;
dev->adev = adev;
nmk_i2c_of_probe(np, dev);
if (dev->tft > max_fifo_threshold) {
dev_warn(&adev->dev, "requested TX FIFO threshold %u, adjusted down to %u\n",
dev->tft, max_fifo_threshold);
dev->tft = max_fifo_threshold;
}
if (dev->rft > max_fifo_threshold) {
dev_warn(&adev->dev, "requested RX FIFO threshold %u, adjusted down to %u\n",
dev->rft, max_fifo_threshold);
dev->rft = max_fifo_threshold;
}
amba_set_drvdata(adev, dev);
dev->virtbase = devm_ioremap(&adev->dev, adev->res.start,
resource_size(&adev->res));
if (IS_ERR(dev->virtbase)) {
ret = -ENOMEM;
goto err_no_mem;
}
dev->irq = adev->irq[0];
ret = devm_request_irq(&adev->dev, dev->irq, i2c_irq_handler, 0,
DRIVER_NAME, dev);
if (ret) {
dev_err(&adev->dev, "cannot claim the irq %d\n", dev->irq);
goto err_no_mem;
}
pm_suspend_ignore_children(&adev->dev, true);
dev->clk = devm_clk_get(&adev->dev, NULL);
if (IS_ERR(dev->clk)) {
dev_err(&adev->dev, "could not get i2c clock\n");
ret = PTR_ERR(dev->clk);
goto err_no_mem;
}
ret = clk_prepare_enable(dev->clk);
if (ret) {
dev_err(&adev->dev, "can't prepare_enable clock\n");
goto err_no_mem;
}
init_hw(dev);
adap = &dev->adap;
adap->dev.of_node = np;
adap->dev.parent = &adev->dev;
adap->owner = THIS_MODULE;
adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
adap->algo = &nmk_i2c_algo;
adap->timeout = msecs_to_jiffies(dev->timeout);
snprintf(adap->name, sizeof(adap->name),
"Nomadik I2C at %pR", &adev->res);
i2c_set_adapdata(adap, dev);
dev_info(&adev->dev,
"initialize %s on virtual base %p\n",
adap->name, dev->virtbase);
ret = i2c_add_adapter(adap);
if (ret) {
dev_err(&adev->dev, "failed to add adapter\n");
goto err_no_adap;
}
pm_runtime_put(&adev->dev);
return 0;
err_no_adap:
clk_disable_unprepare(dev->clk);
err_no_mem:
return ret;
}
static int nmk_i2c_remove(struct amba_device *adev)
{
struct resource *res = &adev->res;
struct nmk_i2c_dev *dev = amba_get_drvdata(adev);
i2c_del_adapter(&dev->adap);
flush_i2c_fifo(dev);
disable_all_interrupts(dev);
clear_all_interrupts(dev);
/* disable the controller */
i2c_clr_bit(dev->virtbase + I2C_CR, I2C_CR_PE);
clk_disable_unprepare(dev->clk);
if (res)
release_mem_region(res->start, resource_size(res));
return 0;
}
static struct i2c_vendor_data vendor_stn8815 = {
.has_mtdws = false,
.fifodepth = 16, /* Guessed from TFTR/RFTR = 7 */
};
static struct i2c_vendor_data vendor_db8500 = {
.has_mtdws = true,
.fifodepth = 32, /* Guessed from TFTR/RFTR = 15 */
};
static struct amba_id nmk_i2c_ids[] = {
{
.id = 0x00180024,
.mask = 0x00ffffff,
.data = &vendor_stn8815,
},
{
.id = 0x00380024,
.mask = 0x00ffffff,
.data = &vendor_db8500,
},
{},
};
MODULE_DEVICE_TABLE(amba, nmk_i2c_ids);
static struct amba_driver nmk_i2c_driver = {
.drv = {
.owner = THIS_MODULE,
.name = DRIVER_NAME,
.pm = &nmk_i2c_pm,
},
.id_table = nmk_i2c_ids,
.probe = nmk_i2c_probe,
.remove = nmk_i2c_remove,
};
static int __init nmk_i2c_init(void)
{
return amba_driver_register(&nmk_i2c_driver);
}
static void __exit nmk_i2c_exit(void)
{
amba_driver_unregister(&nmk_i2c_driver);
}
subsys_initcall(nmk_i2c_init);
module_exit(nmk_i2c_exit);
MODULE_AUTHOR("Sachin Verma, Srinidhi KASAGAR");
MODULE_DESCRIPTION("Nomadik/Ux500 I2C driver");
MODULE_LICENSE("GPL");
|