2 * (C) Copyright 2009-2010
3 * Nokia Siemens Networks, michael.lawnick.ext@nsn.com
5 * Portions Copyright (C) 2010, 2011 Cavium Networks, Inc.
7 * This is a driver for the i2c adapter in Cavium Networks' OCTEON processors.
9 * This file is licensed under the terms of the GNU General Public
10 * License version 2. This program is licensed "as is" without any
11 * warranty of any kind, whether express or implied.
14 #include <linux/platform_device.h>
15 #include <linux/interrupt.h>
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/delay.h>
19 #include <linux/sched.h>
20 #include <linux/slab.h>
21 #include <linux/i2c.h>
25 #include <asm/octeon/octeon.h>
27 #define DRV_NAME "i2c-octeon"
29 /* The previous out-of-tree version was implicitly version 1.0. */
30 #define DRV_VERSION "2.0"
32 /* register offsets */
36 /* Controller command patterns */
37 #define SW_TWSI_V 0x8000000000000000ull
38 #define SW_TWSI_EOP_TWSI_DATA 0x0C00000100000000ull
39 #define SW_TWSI_EOP_TWSI_CTL 0x0C00000200000000ull
40 #define SW_TWSI_EOP_TWSI_CLKCTL 0x0C00000300000000ull
41 #define SW_TWSI_EOP_TWSI_STAT 0x0C00000300000000ull
42 #define SW_TWSI_EOP_TWSI_RST 0x0C00000700000000ull
43 #define SW_TWSI_OP_TWSI_CLK 0x0800000000000000ull
44 #define SW_TWSI_R 0x0100000000000000ull
46 /* Controller command and status bits */
47 #define TWSI_CTL_CE 0x80
48 #define TWSI_CTL_ENAB 0x40
49 #define TWSI_CTL_STA 0x20
50 #define TWSI_CTL_STP 0x10
51 #define TWSI_CTL_IFLG 0x08
52 #define TWSI_CTL_AAK 0x04
54 /* Some status values */
55 #define STAT_START 0x08
56 #define STAT_RSTART 0x10
57 #define STAT_TXADDR_ACK 0x18
58 #define STAT_TXDATA_ACK 0x28
59 #define STAT_RXADDR_ACK 0x40
60 #define STAT_RXDATA_ACK 0x50
61 #define STAT_IDLE 0xF8
64 wait_queue_head_t queue
;
65 struct i2c_adapter adap
;
69 resource_size_t twsi_phys
;
70 void __iomem
*twsi_base
;
71 resource_size_t regsize
;
76 * octeon_i2c_write_sw - write an I2C core register.
77 * @i2c: The struct octeon_i2c.
78 * @eop_reg: Register selector.
79 * @data: Value to be written.
81 * The I2C core registers are accessed indirectly via the SW_TWSI CSR.
83 static void octeon_i2c_write_sw(struct octeon_i2c
*i2c
,
89 __raw_writeq(SW_TWSI_V
| eop_reg
| data
, i2c
->twsi_base
+ SW_TWSI
);
91 tmp
= __raw_readq(i2c
->twsi_base
+ SW_TWSI
);
92 } while ((tmp
& SW_TWSI_V
) != 0);
96 * octeon_i2c_read_sw - write an I2C core register.
97 * @i2c: The struct octeon_i2c.
98 * @eop_reg: Register selector.
102 * The I2C core registers are accessed indirectly via the SW_TWSI CSR.
104 static u8
octeon_i2c_read_sw(struct octeon_i2c
*i2c
, u64 eop_reg
)
108 __raw_writeq(SW_TWSI_V
| eop_reg
| SW_TWSI_R
, i2c
->twsi_base
+ SW_TWSI
);
110 tmp
= __raw_readq(i2c
->twsi_base
+ SW_TWSI
);
111 } while ((tmp
& SW_TWSI_V
) != 0);
117 * octeon_i2c_write_int - write the TWSI_INT register
118 * @i2c: The struct octeon_i2c.
119 * @data: Value to be written.
121 static void octeon_i2c_write_int(struct octeon_i2c
*i2c
, u64 data
)
123 __raw_writeq(data
, i2c
->twsi_base
+ TWSI_INT
);
124 __raw_readq(i2c
->twsi_base
+ TWSI_INT
);
128 * octeon_i2c_int_enable - enable the TS interrupt.
129 * @i2c: The struct octeon_i2c.
131 * The interrupt will be asserted when there is non-STAT_IDLE state in
132 * the SW_TWSI_EOP_TWSI_STAT register.
134 static void octeon_i2c_int_enable(struct octeon_i2c
*i2c
)
136 octeon_i2c_write_int(i2c
, 0x40);
140 * octeon_i2c_int_disable - disable the TS interrupt.
141 * @i2c: The struct octeon_i2c.
143 static void octeon_i2c_int_disable(struct octeon_i2c
*i2c
)
145 octeon_i2c_write_int(i2c
, 0);
149 * octeon_i2c_unblock - unblock the bus.
150 * @i2c: The struct octeon_i2c.
152 * If there was a reset while a device was driving 0 to bus,
153 * bus is blocked. We toggle it free manually by some clock
154 * cycles and send a stop.
156 static void octeon_i2c_unblock(struct octeon_i2c
*i2c
)
160 dev_dbg(i2c
->dev
, "%s\n", __func__
);
161 for (i
= 0; i
< 9; i
++) {
162 octeon_i2c_write_int(i2c
, 0x0);
164 octeon_i2c_write_int(i2c
, 0x200);
167 octeon_i2c_write_int(i2c
, 0x300);
169 octeon_i2c_write_int(i2c
, 0x100);
171 octeon_i2c_write_int(i2c
, 0x0);
175 * octeon_i2c_isr - the interrupt service routine.
176 * @int: The irq, unused.
177 * @dev_id: Our struct octeon_i2c.
179 static irqreturn_t
octeon_i2c_isr(int irq
, void *dev_id
)
181 struct octeon_i2c
*i2c
= dev_id
;
183 octeon_i2c_int_disable(i2c
);
184 wake_up(&i2c
->queue
);
190 static int octeon_i2c_test_iflg(struct octeon_i2c
*i2c
)
192 return (octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
) & TWSI_CTL_IFLG
) != 0;
196 * octeon_i2c_wait - wait for the IFLG to be set.
197 * @i2c: The struct octeon_i2c.
199 * Returns 0 on success, otherwise a negative errno.
201 static int octeon_i2c_wait(struct octeon_i2c
*i2c
)
205 octeon_i2c_int_enable(i2c
);
207 result
= wait_event_timeout(i2c
->queue
,
208 octeon_i2c_test_iflg(i2c
),
211 octeon_i2c_int_disable(i2c
);
214 dev_dbg(i2c
->dev
, "%s: timeout\n", __func__
);
222 * octeon_i2c_start - send START to the bus.
223 * @i2c: The struct octeon_i2c.
225 * Returns 0 on success, otherwise a negative errno.
227 static int octeon_i2c_start(struct octeon_i2c
*i2c
)
232 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
,
233 TWSI_CTL_ENAB
| TWSI_CTL_STA
);
235 result
= octeon_i2c_wait(i2c
);
237 if (octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_STAT
) == STAT_IDLE
) {
239 * Controller refused to send start flag May
240 * be a client is holding SDA low - let's try
243 octeon_i2c_unblock(i2c
);
244 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
,
245 TWSI_CTL_ENAB
| TWSI_CTL_STA
);
247 result
= octeon_i2c_wait(i2c
);
253 data
= octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_STAT
);
254 if ((data
!= STAT_START
) && (data
!= STAT_RSTART
)) {
255 dev_err(i2c
->dev
, "%s: bad status (0x%x)\n", __func__
, data
);
263 * octeon_i2c_stop - send STOP to the bus.
264 * @i2c: The struct octeon_i2c.
266 * Returns 0 on success, otherwise a negative errno.
268 static int octeon_i2c_stop(struct octeon_i2c
*i2c
)
272 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
,
273 TWSI_CTL_ENAB
| TWSI_CTL_STP
);
275 data
= octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_STAT
);
277 if (data
!= STAT_IDLE
) {
278 dev_err(i2c
->dev
, "%s: bad status(0x%x)\n", __func__
, data
);
285 * octeon_i2c_write - send data to the bus.
286 * @i2c: The struct octeon_i2c.
287 * @target: Target address.
288 * @data: Pointer to the data to be sent.
289 * @length: Length of the data.
291 * The address is sent over the bus, then the data.
293 * Returns 0 on success, otherwise a negative errno.
295 static int octeon_i2c_write(struct octeon_i2c
*i2c
, int target
,
296 const u8
*data
, int length
)
301 result
= octeon_i2c_start(i2c
);
305 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_DATA
, target
<< 1);
306 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
, TWSI_CTL_ENAB
);
308 result
= octeon_i2c_wait(i2c
);
312 for (i
= 0; i
< length
; i
++) {
313 tmp
= octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_STAT
);
314 if ((tmp
!= STAT_TXADDR_ACK
) && (tmp
!= STAT_TXDATA_ACK
)) {
316 "%s: bad status before write (0x%x)\n",
321 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_DATA
, data
[i
]);
322 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
, TWSI_CTL_ENAB
);
324 result
= octeon_i2c_wait(i2c
);
333 * octeon_i2c_read - receive data from the bus.
334 * @i2c: The struct octeon_i2c.
335 * @target: Target address.
336 * @data: Pointer to the location to store the datae .
337 * @length: Length of the data.
339 * The address is sent over the bus, then the data is read.
341 * Returns 0 on success, otherwise a negative errno.
343 static int octeon_i2c_read(struct octeon_i2c
*i2c
, int target
,
344 u8
*data
, int length
)
352 result
= octeon_i2c_start(i2c
);
356 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_DATA
, (target
<<1) | 1);
357 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
, TWSI_CTL_ENAB
);
359 result
= octeon_i2c_wait(i2c
);
363 for (i
= 0; i
< length
; i
++) {
364 tmp
= octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_STAT
);
365 if ((tmp
!= STAT_RXDATA_ACK
) && (tmp
!= STAT_RXADDR_ACK
)) {
367 "%s: bad status before read (0x%x)\n",
373 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
,
374 TWSI_CTL_ENAB
| TWSI_CTL_AAK
);
376 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
,
379 result
= octeon_i2c_wait(i2c
);
383 data
[i
] = octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_DATA
);
389 * octeon_i2c_xfer - The driver's master_xfer function.
390 * @adap: Pointer to the i2c_adapter structure.
391 * @msgs: Pointer to the messages to be processed.
392 * @num: Length of the MSGS array.
394 * Returns the number of messages processed, or a negative errno on
397 static int octeon_i2c_xfer(struct i2c_adapter
*adap
,
398 struct i2c_msg
*msgs
,
401 struct i2c_msg
*pmsg
;
404 struct octeon_i2c
*i2c
= i2c_get_adapdata(adap
);
406 for (i
= 0; ret
== 0 && i
< num
; i
++) {
409 "Doing %s %d byte(s) to/from 0x%02x - %d of %d messages\n",
410 pmsg
->flags
& I2C_M_RD
? "read" : "write",
411 pmsg
->len
, pmsg
->addr
, i
+ 1, num
);
412 if (pmsg
->flags
& I2C_M_RD
)
413 ret
= octeon_i2c_read(i2c
, pmsg
->addr
, pmsg
->buf
,
416 ret
= octeon_i2c_write(i2c
, pmsg
->addr
, pmsg
->buf
,
419 octeon_i2c_stop(i2c
);
421 return (ret
!= 0) ? ret
: num
;
424 static u32
octeon_i2c_functionality(struct i2c_adapter
*adap
)
426 return I2C_FUNC_I2C
| I2C_FUNC_SMBUS_EMUL
;
429 static const struct i2c_algorithm octeon_i2c_algo
= {
430 .master_xfer
= octeon_i2c_xfer
,
431 .functionality
= octeon_i2c_functionality
,
434 static struct i2c_adapter octeon_i2c_ops
= {
435 .owner
= THIS_MODULE
,
436 .name
= "OCTEON adapter",
437 .algo
= &octeon_i2c_algo
,
442 * octeon_i2c_setclock - Calculate and set clock divisors.
444 static int octeon_i2c_setclock(struct octeon_i2c
*i2c
)
446 int tclk
, thp_base
, inc
, thp_idx
, mdiv_idx
, ndiv_idx
, foscl
, diff
;
447 int thp
= 0x18, mdiv
= 2, ndiv
= 0, delta_hz
= 1000000;
449 for (ndiv_idx
= 0; ndiv_idx
< 8 && delta_hz
!= 0; ndiv_idx
++) {
451 * An mdiv value of less than 2 seems to not work well
452 * with ds1337 RTCs, so we constrain it to larger
455 for (mdiv_idx
= 15; mdiv_idx
>= 2 && delta_hz
!= 0; mdiv_idx
--) {
457 * For given ndiv and mdiv values check the
458 * two closest thp values.
460 tclk
= i2c
->twsi_freq
* (mdiv_idx
+ 1) * 10;
461 tclk
*= (1 << ndiv_idx
);
462 thp_base
= (i2c
->sys_freq
/ (tclk
* 2)) - 1;
463 for (inc
= 0; inc
<= 1; inc
++) {
464 thp_idx
= thp_base
+ inc
;
465 if (thp_idx
< 5 || thp_idx
> 0xff)
468 foscl
= i2c
->sys_freq
/ (2 * (thp_idx
+ 1));
469 foscl
= foscl
/ (1 << ndiv_idx
);
470 foscl
= foscl
/ (mdiv_idx
+ 1) / 10;
471 diff
= abs(foscl
- i2c
->twsi_freq
);
472 if (diff
< delta_hz
) {
481 octeon_i2c_write_sw(i2c
, SW_TWSI_OP_TWSI_CLK
, thp
);
482 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CLKCTL
, (mdiv
<< 3) | ndiv
);
487 static int octeon_i2c_initlowlevel(struct octeon_i2c
*i2c
)
492 /* disable high level controller, enable bus access */
493 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
, TWSI_CTL_ENAB
);
495 /* reset controller */
496 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_RST
, 0);
498 for (tries
= 10; tries
; tries
--) {
500 status
= octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_STAT
);
501 if (status
== STAT_IDLE
)
504 dev_err(i2c
->dev
, "%s: TWSI_RST failed! (0x%x)\n", __func__
, status
);
508 static int octeon_i2c_probe(struct platform_device
*pdev
)
511 struct octeon_i2c
*i2c
;
512 struct resource
*res_mem
;
514 /* All adaptors have an irq. */
515 irq
= platform_get_irq(pdev
, 0);
519 i2c
= devm_kzalloc(&pdev
->dev
, sizeof(*i2c
), GFP_KERNEL
);
521 dev_err(&pdev
->dev
, "kzalloc failed\n");
525 i2c
->dev
= &pdev
->dev
;
527 res_mem
= platform_get_resource(pdev
, IORESOURCE_MEM
, 0);
529 if (res_mem
== NULL
) {
530 dev_err(i2c
->dev
, "found no memory resource\n");
534 i2c
->twsi_phys
= res_mem
->start
;
535 i2c
->regsize
= resource_size(res_mem
);
538 * "clock-rate" is a legacy binding, the official binding is
539 * "clock-frequency". Try the official one first and then
540 * fall back if it doesn't exist.
542 if (of_property_read_u32(pdev
->dev
.of_node
,
543 "clock-frequency", &i2c
->twsi_freq
) &&
544 of_property_read_u32(pdev
->dev
.of_node
,
545 "clock-rate", &i2c
->twsi_freq
)) {
547 "no I2C 'clock-rate' or 'clock-frequency' property\n");
552 i2c
->sys_freq
= octeon_get_io_clock_rate();
554 if (!devm_request_mem_region(&pdev
->dev
, i2c
->twsi_phys
, i2c
->regsize
,
556 dev_err(i2c
->dev
, "request_mem_region failed\n");
559 i2c
->twsi_base
= devm_ioremap(&pdev
->dev
, i2c
->twsi_phys
, i2c
->regsize
);
561 init_waitqueue_head(&i2c
->queue
);
565 result
= devm_request_irq(&pdev
->dev
, i2c
->irq
,
566 octeon_i2c_isr
, 0, DRV_NAME
, i2c
);
568 dev_err(i2c
->dev
, "failed to attach interrupt\n");
572 result
= octeon_i2c_initlowlevel(i2c
);
574 dev_err(i2c
->dev
, "init low level failed\n");
578 result
= octeon_i2c_setclock(i2c
);
580 dev_err(i2c
->dev
, "clock init failed\n");
584 i2c
->adap
= octeon_i2c_ops
;
585 i2c
->adap
.dev
.parent
= &pdev
->dev
;
586 i2c
->adap
.dev
.of_node
= pdev
->dev
.of_node
;
587 i2c_set_adapdata(&i2c
->adap
, i2c
);
588 platform_set_drvdata(pdev
, i2c
);
590 result
= i2c_add_adapter(&i2c
->adap
);
592 dev_err(i2c
->dev
, "failed to add adapter\n");
595 dev_info(i2c
->dev
, "version %s\n", DRV_VERSION
);
603 static int octeon_i2c_remove(struct platform_device
*pdev
)
605 struct octeon_i2c
*i2c
= platform_get_drvdata(pdev
);
607 i2c_del_adapter(&i2c
->adap
);
611 static struct of_device_id octeon_i2c_match
[] = {
613 .compatible
= "cavium,octeon-3860-twsi",
617 MODULE_DEVICE_TABLE(of
, octeon_i2c_match
);
619 static struct platform_driver octeon_i2c_driver
= {
620 .probe
= octeon_i2c_probe
,
621 .remove
= octeon_i2c_remove
,
624 .of_match_table
= octeon_i2c_match
,
628 module_platform_driver(octeon_i2c_driver
);
630 MODULE_AUTHOR("Michael Lawnick <michael.lawnick.ext@nsn.com>");
631 MODULE_DESCRIPTION("I2C-Bus adapter for Cavium OCTEON processors");
632 MODULE_LICENSE("GPL");
633 MODULE_VERSION(DRV_VERSION
);