2 * (C) Copyright 2009-2010
3 * Nokia Siemens Networks, michael.lawnick.ext@nsn.com
5 * Portions Copyright (C) 2010 - 2016 Cavium, 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 /* Register offsets */
33 /* Controller command patterns */
34 #define SW_TWSI_V BIT_ULL(63) /* Valid bit */
35 #define SW_TWSI_R BIT_ULL(56) /* Result or read bit */
37 /* Controller opcode word (bits 60:57) */
38 #define SW_TWSI_OP_SHIFT 57
39 #define SW_TWSI_OP_TWSI_CLK (4ULL << SW_TWSI_OP_SHIFT)
40 #define SW_TWSI_OP_EOP (6ULL << SW_TWSI_OP_SHIFT) /* Extended opcode */
42 /* Controller extended opcode word (bits 34:32) */
43 #define SW_TWSI_EOP_SHIFT 32
44 #define SW_TWSI_EOP_TWSI_DATA (SW_TWSI_OP_EOP | 1ULL << SW_TWSI_EOP_SHIFT)
45 #define SW_TWSI_EOP_TWSI_CTL (SW_TWSI_OP_EOP | 2ULL << SW_TWSI_EOP_SHIFT)
46 #define SW_TWSI_EOP_TWSI_CLKCTL (SW_TWSI_OP_EOP | 3ULL << SW_TWSI_EOP_SHIFT)
47 #define SW_TWSI_EOP_TWSI_STAT (SW_TWSI_OP_EOP | 3ULL << SW_TWSI_EOP_SHIFT)
48 #define SW_TWSI_EOP_TWSI_RST (SW_TWSI_OP_EOP | 7ULL << SW_TWSI_EOP_SHIFT)
50 /* Controller command and status bits */
51 #define TWSI_CTL_CE 0x80
52 #define TWSI_CTL_ENAB 0x40 /* Bus enable */
53 #define TWSI_CTL_STA 0x20 /* Master-mode start, HW clears when done */
54 #define TWSI_CTL_STP 0x10 /* Master-mode stop, HW clears when done */
55 #define TWSI_CTL_IFLG 0x08 /* HW event, SW writes 0 to ACK */
56 #define TWSI_CTL_AAK 0x04 /* Assert ACK */
58 /* Some status values */
59 #define STAT_START 0x08
60 #define STAT_RSTART 0x10
61 #define STAT_TXADDR_ACK 0x18
62 #define STAT_TXDATA_ACK 0x28
63 #define STAT_RXADDR_ACK 0x40
64 #define STAT_RXDATA_ACK 0x50
65 #define STAT_IDLE 0xF8
68 #define TWSI_INT_CORE_EN BIT_ULL(6)
69 #define TWSI_INT_SDA_OVR BIT_ULL(8)
70 #define TWSI_INT_SCL_OVR BIT_ULL(9)
73 wait_queue_head_t queue
;
74 struct i2c_adapter adap
;
78 void __iomem
*twsi_base
;
83 * octeon_i2c_write_sw - write an I2C core register
84 * @i2c: The struct octeon_i2c
85 * @eop_reg: Register selector
86 * @data: Value to be written
88 * The I2C core registers are accessed indirectly via the SW_TWSI CSR.
90 static void octeon_i2c_write_sw(struct octeon_i2c
*i2c
, u64 eop_reg
, u8 data
)
94 __raw_writeq(SW_TWSI_V
| eop_reg
| data
, i2c
->twsi_base
+ SW_TWSI
);
96 tmp
= __raw_readq(i2c
->twsi_base
+ SW_TWSI
);
97 } while ((tmp
& SW_TWSI_V
) != 0);
101 * octeon_i2c_read_sw - read lower bits of an I2C core register
102 * @i2c: The struct octeon_i2c
103 * @eop_reg: Register selector
107 * The I2C core registers are accessed indirectly via the SW_TWSI CSR.
109 static u8
octeon_i2c_read_sw(struct octeon_i2c
*i2c
, u64 eop_reg
)
113 __raw_writeq(SW_TWSI_V
| eop_reg
| SW_TWSI_R
, i2c
->twsi_base
+ SW_TWSI
);
115 tmp
= __raw_readq(i2c
->twsi_base
+ SW_TWSI
);
116 } while ((tmp
& SW_TWSI_V
) != 0);
122 * octeon_i2c_write_int - write the TWSI_INT register
123 * @i2c: The struct octeon_i2c
124 * @data: Value to be written
126 static void octeon_i2c_write_int(struct octeon_i2c
*i2c
, u64 data
)
128 __raw_writeq(data
, i2c
->twsi_base
+ TWSI_INT
);
129 __raw_readq(i2c
->twsi_base
+ TWSI_INT
);
133 * octeon_i2c_int_enable - enable the CORE interrupt
134 * @i2c: The struct octeon_i2c
136 * The interrupt will be asserted when there is non-STAT_IDLE state in
137 * the SW_TWSI_EOP_TWSI_STAT register.
139 static void octeon_i2c_int_enable(struct octeon_i2c
*i2c
)
141 octeon_i2c_write_int(i2c
, TWSI_INT_CORE_EN
);
144 /* disable the CORE interrupt */
145 static void octeon_i2c_int_disable(struct octeon_i2c
*i2c
)
147 /* clear TS/ST/IFLG events */
148 octeon_i2c_write_int(i2c
, 0);
152 * octeon_i2c_unblock - unblock the bus
153 * @i2c: The struct octeon_i2c
155 * If there was a reset while a device was driving 0 to bus, bus is blocked.
156 * We toggle it free manually by some clock cycles and send a stop.
158 static void octeon_i2c_unblock(struct octeon_i2c
*i2c
)
162 dev_dbg(i2c
->dev
, "%s\n", __func__
);
164 for (i
= 0; i
< 9; i
++) {
165 octeon_i2c_write_int(i2c
, 0);
167 octeon_i2c_write_int(i2c
, TWSI_INT_SCL_OVR
);
170 /* hand-crank a STOP */
171 octeon_i2c_write_int(i2c
, TWSI_INT_SDA_OVR
| TWSI_INT_SCL_OVR
);
173 octeon_i2c_write_int(i2c
, TWSI_INT_SDA_OVR
);
175 octeon_i2c_write_int(i2c
, 0);
178 /* interrupt service routine */
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
);
206 time_left
= wait_event_timeout(i2c
->queue
, octeon_i2c_test_iflg(i2c
),
208 octeon_i2c_int_disable(i2c
);
210 dev_dbg(i2c
->dev
, "%s: timeout\n", __func__
);
218 * octeon_i2c_start - send START to the bus
219 * @i2c: The struct octeon_i2c
221 * Returns 0 on success, otherwise a negative errno.
223 static int octeon_i2c_start(struct octeon_i2c
*i2c
)
228 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
,
229 TWSI_CTL_ENAB
| TWSI_CTL_STA
);
231 result
= octeon_i2c_wait(i2c
);
233 if (octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_STAT
) == STAT_IDLE
) {
235 * Controller refused to send start flag May
236 * be a client is holding SDA low - let's try
239 octeon_i2c_unblock(i2c
);
240 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
,
241 TWSI_CTL_ENAB
| TWSI_CTL_STA
);
242 result
= octeon_i2c_wait(i2c
);
248 data
= octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_STAT
);
249 if ((data
!= STAT_START
) && (data
!= STAT_RSTART
)) {
250 dev_err(i2c
->dev
, "%s: bad status (0x%x)\n", __func__
, data
);
257 /* send STOP to the bus */
258 static void octeon_i2c_stop(struct octeon_i2c
*i2c
)
260 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
,
261 TWSI_CTL_ENAB
| TWSI_CTL_STP
);
265 * octeon_i2c_write - send data to the bus via low-level controller
266 * @i2c: The struct octeon_i2c
267 * @target: Target address
268 * @data: Pointer to the data to be sent
269 * @length: Length of the data
271 * The address is sent over the bus, then the data.
273 * Returns 0 on success, otherwise a negative errno.
275 static int octeon_i2c_write(struct octeon_i2c
*i2c
, int target
,
276 const u8
*data
, int length
)
281 result
= octeon_i2c_start(i2c
);
285 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_DATA
, target
<< 1);
286 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
, TWSI_CTL_ENAB
);
288 result
= octeon_i2c_wait(i2c
);
292 for (i
= 0; i
< length
; i
++) {
293 tmp
= octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_STAT
);
295 if ((tmp
!= STAT_TXADDR_ACK
) && (tmp
!= STAT_TXDATA_ACK
)) {
297 "%s: bad status before write (0x%x)\n",
302 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_DATA
, data
[i
]);
303 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
, TWSI_CTL_ENAB
);
305 result
= octeon_i2c_wait(i2c
);
314 * octeon_i2c_read - receive data from the bus via low-level controller
315 * @i2c: The struct octeon_i2c
316 * @target: Target address
317 * @data: Pointer to the location to store the data
318 * @rlength: Length of the data
319 * @recv_len: flag for length byte
321 * The address is sent over the bus, then the data is read.
323 * Returns 0 on success, otherwise a negative errno.
325 static int octeon_i2c_read(struct octeon_i2c
*i2c
, int target
,
326 u8
*data
, u16
*rlength
, bool recv_len
)
328 int i
, result
, length
= *rlength
;
334 result
= octeon_i2c_start(i2c
);
338 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_DATA
, (target
<< 1) | 1);
339 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
, TWSI_CTL_ENAB
);
341 result
= octeon_i2c_wait(i2c
);
345 for (i
= 0; i
< length
; i
++) {
346 tmp
= octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_STAT
);
348 if ((tmp
!= STAT_RXDATA_ACK
) && (tmp
!= STAT_RXADDR_ACK
)) {
350 "%s: bad status before read (0x%x)\n",
356 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
,
357 TWSI_CTL_ENAB
| TWSI_CTL_AAK
);
359 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
,
362 result
= octeon_i2c_wait(i2c
);
366 data
[i
] = octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_DATA
);
367 if (recv_len
&& i
== 0) {
368 if (data
[i
] > I2C_SMBUS_BLOCK_MAX
+ 1) {
370 "%s: read len > I2C_SMBUS_BLOCK_MAX %d\n",
382 * octeon_i2c_xfer - The driver's master_xfer function
383 * @adap: Pointer to the i2c_adapter structure
384 * @msgs: Pointer to the messages to be processed
385 * @num: Length of the MSGS array
387 * Returns the number of messages processed, or a negative errno on failure.
389 static int octeon_i2c_xfer(struct i2c_adapter
*adap
, struct i2c_msg
*msgs
,
392 struct octeon_i2c
*i2c
= i2c_get_adapdata(adap
);
395 for (i
= 0; ret
== 0 && i
< num
; i
++) {
396 struct i2c_msg
*pmsg
= &msgs
[i
];
399 "Doing %s %d byte(s) to/from 0x%02x - %d of %d messages\n",
400 pmsg
->flags
& I2C_M_RD
? "read" : "write",
401 pmsg
->len
, pmsg
->addr
, i
+ 1, num
);
402 if (pmsg
->flags
& I2C_M_RD
)
403 ret
= octeon_i2c_read(i2c
, pmsg
->addr
, pmsg
->buf
,
404 &pmsg
->len
, pmsg
->flags
& I2C_M_RECV_LEN
);
406 ret
= octeon_i2c_write(i2c
, pmsg
->addr
, pmsg
->buf
,
409 octeon_i2c_stop(i2c
);
411 return (ret
!= 0) ? ret
: num
;
414 static u32
octeon_i2c_functionality(struct i2c_adapter
*adap
)
416 return I2C_FUNC_I2C
| I2C_FUNC_SMBUS_EMUL
|
417 I2C_FUNC_SMBUS_READ_BLOCK_DATA
| I2C_SMBUS_BLOCK_PROC_CALL
;
420 static const struct i2c_algorithm octeon_i2c_algo
= {
421 .master_xfer
= octeon_i2c_xfer
,
422 .functionality
= octeon_i2c_functionality
,
425 static struct i2c_adapter octeon_i2c_ops
= {
426 .owner
= THIS_MODULE
,
427 .name
= "OCTEON adapter",
428 .algo
= &octeon_i2c_algo
,
432 /* calculate and set clock divisors */
433 static void octeon_i2c_set_clock(struct octeon_i2c
*i2c
)
435 int tclk
, thp_base
, inc
, thp_idx
, mdiv_idx
, ndiv_idx
, foscl
, diff
;
436 int thp
= 0x18, mdiv
= 2, ndiv
= 0, delta_hz
= 1000000;
438 for (ndiv_idx
= 0; ndiv_idx
< 8 && delta_hz
!= 0; ndiv_idx
++) {
440 * An mdiv value of less than 2 seems to not work well
441 * with ds1337 RTCs, so we constrain it to larger values.
443 for (mdiv_idx
= 15; mdiv_idx
>= 2 && delta_hz
!= 0; mdiv_idx
--) {
445 * For given ndiv and mdiv values check the
446 * two closest thp values.
448 tclk
= i2c
->twsi_freq
* (mdiv_idx
+ 1) * 10;
449 tclk
*= (1 << ndiv_idx
);
450 thp_base
= (i2c
->sys_freq
/ (tclk
* 2)) - 1;
452 for (inc
= 0; inc
<= 1; inc
++) {
453 thp_idx
= thp_base
+ inc
;
454 if (thp_idx
< 5 || thp_idx
> 0xff)
457 foscl
= i2c
->sys_freq
/ (2 * (thp_idx
+ 1));
458 foscl
= foscl
/ (1 << ndiv_idx
);
459 foscl
= foscl
/ (mdiv_idx
+ 1) / 10;
460 diff
= abs(foscl
- i2c
->twsi_freq
);
461 if (diff
< delta_hz
) {
470 octeon_i2c_write_sw(i2c
, SW_TWSI_OP_TWSI_CLK
, thp
);
471 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CLKCTL
, (mdiv
<< 3) | ndiv
);
474 static int octeon_i2c_init_lowlevel(struct octeon_i2c
*i2c
)
479 /* disable high level controller, enable bus access */
480 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_CTL
, TWSI_CTL_ENAB
);
482 /* reset controller */
483 octeon_i2c_write_sw(i2c
, SW_TWSI_EOP_TWSI_RST
, 0);
485 for (tries
= 10; tries
; tries
--) {
487 status
= octeon_i2c_read_sw(i2c
, SW_TWSI_EOP_TWSI_STAT
);
488 if (status
== STAT_IDLE
)
491 dev_err(i2c
->dev
, "%s: TWSI_RST failed! (0x%x)\n", __func__
, status
);
495 static int octeon_i2c_probe(struct platform_device
*pdev
)
497 struct device_node
*node
= pdev
->dev
.of_node
;
498 struct resource
*res_mem
;
499 struct octeon_i2c
*i2c
;
502 /* All adaptors have an irq. */
503 irq
= platform_get_irq(pdev
, 0);
507 i2c
= devm_kzalloc(&pdev
->dev
, sizeof(*i2c
), GFP_KERNEL
);
512 i2c
->dev
= &pdev
->dev
;
514 res_mem
= platform_get_resource(pdev
, IORESOURCE_MEM
, 0);
515 i2c
->twsi_base
= devm_ioremap_resource(&pdev
->dev
, res_mem
);
516 if (IS_ERR(i2c
->twsi_base
)) {
517 result
= PTR_ERR(i2c
->twsi_base
);
522 * "clock-rate" is a legacy binding, the official binding is
523 * "clock-frequency". Try the official one first and then
524 * fall back if it doesn't exist.
526 if (of_property_read_u32(node
, "clock-frequency", &i2c
->twsi_freq
) &&
527 of_property_read_u32(node
, "clock-rate", &i2c
->twsi_freq
)) {
529 "no I2C 'clock-rate' or 'clock-frequency' property\n");
534 i2c
->sys_freq
= octeon_get_io_clock_rate();
536 init_waitqueue_head(&i2c
->queue
);
540 result
= devm_request_irq(&pdev
->dev
, i2c
->irq
,
541 octeon_i2c_isr
, 0, DRV_NAME
, i2c
);
543 dev_err(i2c
->dev
, "failed to attach interrupt\n");
547 result
= octeon_i2c_init_lowlevel(i2c
);
549 dev_err(i2c
->dev
, "init low level failed\n");
553 octeon_i2c_set_clock(i2c
);
555 i2c
->adap
= octeon_i2c_ops
;
556 i2c
->adap
.dev
.parent
= &pdev
->dev
;
557 i2c
->adap
.dev
.of_node
= node
;
558 i2c_set_adapdata(&i2c
->adap
, i2c
);
559 platform_set_drvdata(pdev
, i2c
);
561 result
= i2c_add_adapter(&i2c
->adap
);
563 dev_err(i2c
->dev
, "failed to add adapter\n");
566 dev_info(i2c
->dev
, "probed\n");
573 static int octeon_i2c_remove(struct platform_device
*pdev
)
575 struct octeon_i2c
*i2c
= platform_get_drvdata(pdev
);
577 i2c_del_adapter(&i2c
->adap
);
581 static const struct of_device_id octeon_i2c_match
[] = {
582 { .compatible
= "cavium,octeon-3860-twsi", },
585 MODULE_DEVICE_TABLE(of
, octeon_i2c_match
);
587 static struct platform_driver octeon_i2c_driver
= {
588 .probe
= octeon_i2c_probe
,
589 .remove
= octeon_i2c_remove
,
592 .of_match_table
= octeon_i2c_match
,
596 module_platform_driver(octeon_i2c_driver
);
598 MODULE_AUTHOR("Michael Lawnick <michael.lawnick.ext@nsn.com>");
599 MODULE_DESCRIPTION("I2C-Bus adapter for Cavium OCTEON processors");
600 MODULE_LICENSE("GPL");