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/init.h>
22 #include <linux/i2c.h>
26 #include <asm/octeon/octeon.h>
28 #define DRV_NAME "i2c-octeon"
30 /* The previous out-of-tree version was implicitly version 1.0. */
31 #define DRV_VERSION "2.0"
33 /* register offsets */
37 /* Controller command patterns */
38 #define SW_TWSI_V 0x8000000000000000ull
39 #define SW_TWSI_EOP_TWSI_DATA 0x0C00000100000000ull
40 #define SW_TWSI_EOP_TWSI_CTL 0x0C00000200000000ull
41 #define SW_TWSI_EOP_TWSI_CLKCTL 0x0C00000300000000ull
42 #define SW_TWSI_EOP_TWSI_STAT 0x0C00000300000000ull
43 #define SW_TWSI_EOP_TWSI_RST 0x0C00000700000000ull
44 #define SW_TWSI_OP_TWSI_CLK 0x0800000000000000ull
45 #define SW_TWSI_R 0x0100000000000000ull
47 /* Controller command and status bits */
48 #define TWSI_CTL_CE 0x80
49 #define TWSI_CTL_ENAB 0x40
50 #define TWSI_CTL_STA 0x20
51 #define TWSI_CTL_STP 0x10
52 #define TWSI_CTL_IFLG 0x08
53 #define TWSI_CTL_AAK 0x04
55 /* Some status values */
56 #define STAT_START 0x08
57 #define STAT_RSTART 0x10
58 #define STAT_TXADDR_ACK 0x18
59 #define STAT_TXDATA_ACK 0x28
60 #define STAT_RXADDR_ACK 0x40
61 #define STAT_RXDATA_ACK 0x50
62 #define STAT_IDLE 0xF8
65 wait_queue_head_t queue
;
66 struct i2c_adapter adap
;
70 resource_size_t twsi_phys
;
71 void __iomem
*twsi_base
;
72 resource_size_t regsize
;
77 * octeon_i2c_write_sw - write an I2C core register.
78 * @i2c: The struct octeon_i2c.
79 * @eop_reg: Register selector.
80 * @data: Value to be written.
82 * The I2C core registers are accessed indirectly via the SW_TWSI CSR.
84 static void octeon_i2c_write_sw(struct octeon_i2c
*i2c
,
90 __raw_writeq(SW_TWSI_V
| eop_reg
| data
, i2c
->twsi_base
+ SW_TWSI
);
92 tmp
= __raw_readq(i2c
->twsi_base
+ SW_TWSI
);
93 } while ((tmp
& SW_TWSI_V
) != 0);
97 * octeon_i2c_read_sw - write an I2C core register.
98 * @i2c: The struct octeon_i2c.
99 * @eop_reg: Register selector.
103 * The I2C core registers are accessed indirectly via the SW_TWSI CSR.
105 static u8
octeon_i2c_read_sw(struct octeon_i2c
*i2c
, u64 eop_reg
)
109 __raw_writeq(SW_TWSI_V
| eop_reg
| SW_TWSI_R
, i2c
->twsi_base
+ SW_TWSI
);
111 tmp
= __raw_readq(i2c
->twsi_base
+ SW_TWSI
);
112 } while ((tmp
& SW_TWSI_V
) != 0);
118 * octeon_i2c_write_int - write the TWSI_INT register
119 * @i2c: The struct octeon_i2c.
120 * @data: Value to be written.
122 static void octeon_i2c_write_int(struct octeon_i2c
*i2c
, u64 data
)
124 __raw_writeq(data
, i2c
->twsi_base
+ TWSI_INT
);
125 __raw_readq(i2c
->twsi_base
+ TWSI_INT
);
129 * octeon_i2c_int_enable - enable the TS interrupt.
130 * @i2c: The struct octeon_i2c.
132 * The interrupt will be asserted when there is non-STAT_IDLE state in
133 * the SW_TWSI_EOP_TWSI_STAT register.
135 static void octeon_i2c_int_enable(struct octeon_i2c
*i2c
)
137 octeon_i2c_write_int(i2c
, 0x40);
141 * octeon_i2c_int_disable - disable the TS interrupt.
142 * @i2c: The struct octeon_i2c.
144 static void octeon_i2c_int_disable(struct octeon_i2c
*i2c
)
146 octeon_i2c_write_int(i2c
, 0);
150 * octeon_i2c_unblock - unblock the bus.
151 * @i2c: The struct octeon_i2c.
153 * If there was a reset while a device was driving 0 to bus,
154 * bus is blocked. We toggle it free manually by some clock
155 * cycles and send a stop.
157 static void octeon_i2c_unblock(struct octeon_i2c
*i2c
)
161 dev_dbg(i2c
->dev
, "%s\n", __func__
);
162 for (i
= 0; i
< 9; i
++) {
163 octeon_i2c_write_int(i2c
, 0x0);
165 octeon_i2c_write_int(i2c
, 0x200);
168 octeon_i2c_write_int(i2c
, 0x300);
170 octeon_i2c_write_int(i2c
, 0x100);
172 octeon_i2c_write_int(i2c
, 0x0);
176 * octeon_i2c_isr - the interrupt service routine.
177 * @int: The irq, unused.
178 * @dev_id: Our struct octeon_i2c.
180 static irqreturn_t
octeon_i2c_isr(int irq
, void *dev_id
)
182 struct octeon_i2c
*i2c
= dev_id
;
184 octeon_i2c_int_disable(i2c
);
185 wake_up(&i2c
->queue
);
191 static int octeon_i2c_test_iflg(struct octeon_i2c
*i2c
)
193 return (octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
) & TWSI_CTL_IFLG
) != 0;
197 * octeon_i2c_wait - wait for the IFLG to be set.
198 * @i2c: The struct octeon_i2c.
200 * Returns 0 on success, otherwise a negative errno.
202 static int octeon_i2c_wait(struct octeon_i2c
*i2c
)
206 octeon_i2c_int_enable(i2c
);
208 result
= wait_event_timeout(i2c
->queue
,
209 octeon_i2c_test_iflg(i2c
),
212 octeon_i2c_int_disable(i2c
);
215 dev_dbg(i2c
->dev
, "%s: wait interrupted\n", __func__
);
217 } else if (result
== 0) {
218 dev_dbg(i2c
->dev
, "%s: timeout\n", __func__
);
226 * octeon_i2c_start - send START to the bus.
227 * @i2c: The struct octeon_i2c.
229 * Returns 0 on success, otherwise a negative errno.
231 static int octeon_i2c_start(struct octeon_i2c
*i2c
)
236 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
,
237 TWSI_CTL_ENAB
| TWSI_CTL_STA
);
239 result
= octeon_i2c_wait(i2c
);
241 if (octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_STAT
) == STAT_IDLE
) {
243 * Controller refused to send start flag May
244 * be a client is holding SDA low - let's try
247 octeon_i2c_unblock(i2c
);
248 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
,
249 TWSI_CTL_ENAB
| TWSI_CTL_STA
);
251 result
= octeon_i2c_wait(i2c
);
257 data
= octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_STAT
);
258 if ((data
!= STAT_START
) && (data
!= STAT_RSTART
)) {
259 dev_err(i2c
->dev
, "%s: bad status (0x%x)\n", __func__
, data
);
267 * octeon_i2c_stop - send STOP to the bus.
268 * @i2c: The struct octeon_i2c.
270 * Returns 0 on success, otherwise a negative errno.
272 static int octeon_i2c_stop(struct octeon_i2c
*i2c
)
276 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
,
277 TWSI_CTL_ENAB
| TWSI_CTL_STP
);
279 data
= octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_STAT
);
281 if (data
!= STAT_IDLE
) {
282 dev_err(i2c
->dev
, "%s: bad status(0x%x)\n", __func__
, data
);
289 * octeon_i2c_write - send data to the bus.
290 * @i2c: The struct octeon_i2c.
291 * @target: Target address.
292 * @data: Pointer to the data to be sent.
293 * @length: Length of the data.
295 * The address is sent over the bus, then the data.
297 * Returns 0 on success, otherwise a negative errno.
299 static int octeon_i2c_write(struct octeon_i2c
*i2c
, int target
,
300 const u8
*data
, int length
)
305 result
= octeon_i2c_start(i2c
);
309 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_DATA
, target
<< 1);
310 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
, TWSI_CTL_ENAB
);
312 result
= octeon_i2c_wait(i2c
);
316 for (i
= 0; i
< length
; i
++) {
317 tmp
= octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_STAT
);
318 if ((tmp
!= STAT_TXADDR_ACK
) && (tmp
!= STAT_TXDATA_ACK
)) {
320 "%s: bad status before write (0x%x)\n",
325 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_DATA
, data
[i
]);
326 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
, TWSI_CTL_ENAB
);
328 result
= octeon_i2c_wait(i2c
);
337 * octeon_i2c_read - receive data from the bus.
338 * @i2c: The struct octeon_i2c.
339 * @target: Target address.
340 * @data: Pointer to the location to store the datae .
341 * @length: Length of the data.
343 * The address is sent over the bus, then the data is read.
345 * Returns 0 on success, otherwise a negative errno.
347 static int octeon_i2c_read(struct octeon_i2c
*i2c
, int target
,
348 u8
*data
, int length
)
356 result
= octeon_i2c_start(i2c
);
360 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_DATA
, (target
<<1) | 1);
361 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
, TWSI_CTL_ENAB
);
363 result
= octeon_i2c_wait(i2c
);
367 for (i
= 0; i
< length
; i
++) {
368 tmp
= octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_STAT
);
369 if ((tmp
!= STAT_RXDATA_ACK
) && (tmp
!= STAT_RXADDR_ACK
)) {
371 "%s: bad status before read (0x%x)\n",
377 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
,
378 TWSI_CTL_ENAB
| TWSI_CTL_AAK
);
380 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
,
383 result
= octeon_i2c_wait(i2c
);
387 data
[i
] = octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_DATA
);
393 * octeon_i2c_xfer - The driver's master_xfer function.
394 * @adap: Pointer to the i2c_adapter structure.
395 * @msgs: Pointer to the messages to be processed.
396 * @num: Length of the MSGS array.
398 * Returns the number of messages processed, or a negative errno on
401 static int octeon_i2c_xfer(struct i2c_adapter
*adap
,
402 struct i2c_msg
*msgs
,
405 struct i2c_msg
*pmsg
;
408 struct octeon_i2c
*i2c
= i2c_get_adapdata(adap
);
410 for (i
= 0; ret
== 0 && i
< num
; i
++) {
413 "Doing %s %d byte(s) to/from 0x%02x - %d of %d messages\n",
414 pmsg
->flags
& I2C_M_RD
? "read" : "write",
415 pmsg
->len
, pmsg
->addr
, i
+ 1, num
);
416 if (pmsg
->flags
& I2C_M_RD
)
417 ret
= octeon_i2c_read(i2c
, pmsg
->addr
, pmsg
->buf
,
420 ret
= octeon_i2c_write(i2c
, pmsg
->addr
, pmsg
->buf
,
423 octeon_i2c_stop(i2c
);
425 return (ret
!= 0) ? ret
: num
;
428 static u32
octeon_i2c_functionality(struct i2c_adapter
*adap
)
430 return I2C_FUNC_I2C
| I2C_FUNC_SMBUS_EMUL
;
433 static const struct i2c_algorithm octeon_i2c_algo
= {
434 .master_xfer
= octeon_i2c_xfer
,
435 .functionality
= octeon_i2c_functionality
,
438 static struct i2c_adapter octeon_i2c_ops
= {
439 .owner
= THIS_MODULE
,
440 .name
= "OCTEON adapter",
441 .algo
= &octeon_i2c_algo
,
446 * octeon_i2c_setclock - Calculate and set clock divisors.
448 static int octeon_i2c_setclock(struct octeon_i2c
*i2c
)
450 int tclk
, thp_base
, inc
, thp_idx
, mdiv_idx
, ndiv_idx
, foscl
, diff
;
451 int thp
= 0x18, mdiv
= 2, ndiv
= 0, delta_hz
= 1000000;
453 for (ndiv_idx
= 0; ndiv_idx
< 8 && delta_hz
!= 0; ndiv_idx
++) {
455 * An mdiv value of less than 2 seems to not work well
456 * with ds1337 RTCs, so we constrain it to larger
459 for (mdiv_idx
= 15; mdiv_idx
>= 2 && delta_hz
!= 0; mdiv_idx
--) {
461 * For given ndiv and mdiv values check the
462 * two closest thp values.
464 tclk
= i2c
->twsi_freq
* (mdiv_idx
+ 1) * 10;
465 tclk
*= (1 << ndiv_idx
);
466 thp_base
= (i2c
->sys_freq
/ (tclk
* 2)) - 1;
467 for (inc
= 0; inc
<= 1; inc
++) {
468 thp_idx
= thp_base
+ inc
;
469 if (thp_idx
< 5 || thp_idx
> 0xff)
472 foscl
= i2c
->sys_freq
/ (2 * (thp_idx
+ 1));
473 foscl
= foscl
/ (1 << ndiv_idx
);
474 foscl
= foscl
/ (mdiv_idx
+ 1) / 10;
475 diff
= abs(foscl
- i2c
->twsi_freq
);
476 if (diff
< delta_hz
) {
485 octeon_i2c_write_sw(i2c
, SW_TWSI_OP_TWSI_CLK
, thp
);
486 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CLKCTL
, (mdiv
<< 3) | ndiv
);
491 static int octeon_i2c_initlowlevel(struct octeon_i2c
*i2c
)
496 /* disable high level controller, enable bus access */
497 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
, TWSI_CTL_ENAB
);
499 /* reset controller */
500 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_RST
, 0);
502 for (tries
= 10; tries
; tries
--) {
504 status
= octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_STAT
);
505 if (status
== STAT_IDLE
)
508 dev_err(i2c
->dev
, "%s: TWSI_RST failed! (0x%x)\n", __func__
, status
);
512 static int octeon_i2c_probe(struct platform_device
*pdev
)
515 struct octeon_i2c
*i2c
;
516 struct resource
*res_mem
;
518 /* All adaptors have an irq. */
519 irq
= platform_get_irq(pdev
, 0);
523 i2c
= devm_kzalloc(&pdev
->dev
, sizeof(*i2c
), GFP_KERNEL
);
525 dev_err(&pdev
->dev
, "kzalloc failed\n");
529 i2c
->dev
= &pdev
->dev
;
531 res_mem
= platform_get_resource(pdev
, IORESOURCE_MEM
, 0);
533 if (res_mem
== NULL
) {
534 dev_err(i2c
->dev
, "found no memory resource\n");
538 i2c
->twsi_phys
= res_mem
->start
;
539 i2c
->regsize
= resource_size(res_mem
);
542 * "clock-rate" is a legacy binding, the official binding is
543 * "clock-frequency". Try the official one first and then
544 * fall back if it doesn't exist.
546 if (of_property_read_u32(pdev
->dev
.of_node
,
547 "clock-frequency", &i2c
->twsi_freq
) &&
548 of_property_read_u32(pdev
->dev
.of_node
,
549 "clock-rate", &i2c
->twsi_freq
)) {
551 "no I2C 'clock-rate' or 'clock-frequency' property\n");
556 i2c
->sys_freq
= octeon_get_io_clock_rate();
558 if (!devm_request_mem_region(&pdev
->dev
, i2c
->twsi_phys
, i2c
->regsize
,
560 dev_err(i2c
->dev
, "request_mem_region failed\n");
563 i2c
->twsi_base
= devm_ioremap(&pdev
->dev
, i2c
->twsi_phys
, i2c
->regsize
);
565 init_waitqueue_head(&i2c
->queue
);
569 result
= devm_request_irq(&pdev
->dev
, i2c
->irq
,
570 octeon_i2c_isr
, 0, DRV_NAME
, i2c
);
572 dev_err(i2c
->dev
, "failed to attach interrupt\n");
576 result
= octeon_i2c_initlowlevel(i2c
);
578 dev_err(i2c
->dev
, "init low level failed\n");
582 result
= octeon_i2c_setclock(i2c
);
584 dev_err(i2c
->dev
, "clock init failed\n");
588 i2c
->adap
= octeon_i2c_ops
;
589 i2c
->adap
.dev
.parent
= &pdev
->dev
;
590 i2c
->adap
.dev
.of_node
= pdev
->dev
.of_node
;
591 i2c_set_adapdata(&i2c
->adap
, i2c
);
592 platform_set_drvdata(pdev
, i2c
);
594 result
= i2c_add_adapter(&i2c
->adap
);
596 dev_err(i2c
->dev
, "failed to add adapter\n");
599 dev_info(i2c
->dev
, "version %s\n", DRV_VERSION
);
607 static int octeon_i2c_remove(struct platform_device
*pdev
)
609 struct octeon_i2c
*i2c
= platform_get_drvdata(pdev
);
611 i2c_del_adapter(&i2c
->adap
);
615 static struct of_device_id octeon_i2c_match
[] = {
617 .compatible
= "cavium,octeon-3860-twsi",
621 MODULE_DEVICE_TABLE(of
, octeon_i2c_match
);
623 static struct platform_driver octeon_i2c_driver
= {
624 .probe
= octeon_i2c_probe
,
625 .remove
= octeon_i2c_remove
,
627 .owner
= THIS_MODULE
,
629 .of_match_table
= octeon_i2c_match
,
633 module_platform_driver(octeon_i2c_driver
);
635 MODULE_AUTHOR("Michael Lawnick <michael.lawnick.ext@nsn.com>");
636 MODULE_DESCRIPTION("I2C-Bus adapter for Cavium OCTEON processors");
637 MODULE_LICENSE("GPL");
638 MODULE_VERSION(DRV_VERSION
);