2 * I2C bus driver for the Cadence I2C controller.
4 * Copyright (C) 2009 - 2014 Xilinx, Inc.
6 * This program is free software; you can redistribute it
7 * and/or modify it under the terms of the GNU General Public
8 * License as published by the Free Software Foundation;
9 * either version 2 of the License, or (at your option) any
13 #include <linux/clk.h>
14 #include <linux/delay.h>
15 #include <linux/i2c.h>
16 #include <linux/interrupt.h>
18 #include <linux/module.h>
19 #include <linux/platform_device.h>
21 /* Register offsets for the I2C device. */
22 #define CDNS_I2C_CR_OFFSET 0x00 /* Control Register, RW */
23 #define CDNS_I2C_SR_OFFSET 0x04 /* Status Register, RO */
24 #define CDNS_I2C_ADDR_OFFSET 0x08 /* I2C Address Register, RW */
25 #define CDNS_I2C_DATA_OFFSET 0x0C /* I2C Data Register, RW */
26 #define CDNS_I2C_ISR_OFFSET 0x10 /* IRQ Status Register, RW */
27 #define CDNS_I2C_XFER_SIZE_OFFSET 0x14 /* Transfer Size Register, RW */
28 #define CDNS_I2C_TIME_OUT_OFFSET 0x1C /* Time Out Register, RW */
29 #define CDNS_I2C_IER_OFFSET 0x24 /* IRQ Enable Register, WO */
30 #define CDNS_I2C_IDR_OFFSET 0x28 /* IRQ Disable Register, WO */
32 /* Control Register Bit mask definitions */
33 #define CDNS_I2C_CR_HOLD BIT(4) /* Hold Bus bit */
34 #define CDNS_I2C_CR_ACK_EN BIT(3)
35 #define CDNS_I2C_CR_NEA BIT(2)
36 #define CDNS_I2C_CR_MS BIT(1)
37 /* Read or Write Master transfer 0 = Transmitter, 1 = Receiver */
38 #define CDNS_I2C_CR_RW BIT(0)
39 /* 1 = Auto init FIFO to zeroes */
40 #define CDNS_I2C_CR_CLR_FIFO BIT(6)
41 #define CDNS_I2C_CR_DIVA_SHIFT 14
42 #define CDNS_I2C_CR_DIVA_MASK (3 << CDNS_I2C_CR_DIVA_SHIFT)
43 #define CDNS_I2C_CR_DIVB_SHIFT 8
44 #define CDNS_I2C_CR_DIVB_MASK (0x3f << CDNS_I2C_CR_DIVB_SHIFT)
46 /* Status Register Bit mask definitions */
47 #define CDNS_I2C_SR_BA BIT(8)
48 #define CDNS_I2C_SR_RXDV BIT(5)
51 * I2C Address Register Bit mask definitions
52 * Normal addressing mode uses [6:0] bits. Extended addressing mode uses [9:0]
53 * bits. A write access to this register always initiates a transfer if the I2C
56 #define CDNS_I2C_ADDR_MASK 0x000003FF /* I2C Address Mask */
59 * I2C Interrupt Registers Bit mask definitions
60 * All the four interrupt registers (Status/Mask/Enable/Disable) have the same
63 #define CDNS_I2C_IXR_ARB_LOST BIT(9)
64 #define CDNS_I2C_IXR_RX_UNF BIT(7)
65 #define CDNS_I2C_IXR_TX_OVF BIT(6)
66 #define CDNS_I2C_IXR_RX_OVF BIT(5)
67 #define CDNS_I2C_IXR_SLV_RDY BIT(4)
68 #define CDNS_I2C_IXR_TO BIT(3)
69 #define CDNS_I2C_IXR_NACK BIT(2)
70 #define CDNS_I2C_IXR_DATA BIT(1)
71 #define CDNS_I2C_IXR_COMP BIT(0)
73 #define CDNS_I2C_IXR_ALL_INTR_MASK (CDNS_I2C_IXR_ARB_LOST | \
74 CDNS_I2C_IXR_RX_UNF | \
75 CDNS_I2C_IXR_TX_OVF | \
76 CDNS_I2C_IXR_RX_OVF | \
77 CDNS_I2C_IXR_SLV_RDY | \
83 #define CDNS_I2C_IXR_ERR_INTR_MASK (CDNS_I2C_IXR_ARB_LOST | \
84 CDNS_I2C_IXR_RX_UNF | \
85 CDNS_I2C_IXR_TX_OVF | \
86 CDNS_I2C_IXR_RX_OVF | \
89 #define CDNS_I2C_ENABLED_INTR_MASK (CDNS_I2C_IXR_ARB_LOST | \
90 CDNS_I2C_IXR_RX_UNF | \
91 CDNS_I2C_IXR_TX_OVF | \
92 CDNS_I2C_IXR_RX_OVF | \
97 #define CDNS_I2C_TIMEOUT msecs_to_jiffies(1000)
99 #define CDNS_I2C_FIFO_DEPTH 16
100 /* FIFO depth at which the DATA interrupt occurs */
101 #define CDNS_I2C_DATA_INTR_DEPTH (CDNS_I2C_FIFO_DEPTH - 2)
102 #define CDNS_I2C_MAX_TRANSFER_SIZE 255
103 /* Transfer size in multiples of data interrupt depth */
104 #define CDNS_I2C_TRANSFER_SIZE (CDNS_I2C_MAX_TRANSFER_SIZE - 3)
106 #define DRIVER_NAME "cdns-i2c"
108 #define CDNS_I2C_SPEED_MAX 400000
109 #define CDNS_I2C_SPEED_DEFAULT 100000
111 #define CDNS_I2C_DIVA_MAX 4
112 #define CDNS_I2C_DIVB_MAX 64
114 #define CDNS_I2C_TIMEOUT_MAX 0xFF
116 #define cdns_i2c_readreg(offset) readl_relaxed(id->membase + offset)
117 #define cdns_i2c_writereg(val, offset) writel_relaxed(val, id->membase + offset)
120 * struct cdns_i2c - I2C device private data structure
121 * @membase: Base address of the I2C device
122 * @adap: I2C adapter instance
123 * @p_msg: Message pointer
124 * @err_status: Error status in Interrupt Status Register
125 * @xfer_done: Transfer complete status
126 * @p_send_buf: Pointer to transmit buffer
127 * @p_recv_buf: Pointer to receive buffer
128 * @suspended: Flag holding the device's PM status
129 * @send_count: Number of bytes still expected to send
130 * @recv_count: Number of bytes still expected to receive
132 * @input_clk: Input clock to I2C controller
133 * @i2c_clk: Maximum I2C clock speed
134 * @bus_hold_flag: Flag used in repeated start for clearing HOLD bit
135 * @clk: Pointer to struct clk
136 * @clk_rate_change_nb: Notifier block for clock rate changes
139 void __iomem
*membase
;
140 struct i2c_adapter adap
;
141 struct i2c_msg
*p_msg
;
143 struct completion xfer_done
;
144 unsigned char *p_send_buf
;
145 unsigned char *p_recv_buf
;
147 unsigned int send_count
;
148 unsigned int recv_count
;
150 unsigned long input_clk
;
151 unsigned int i2c_clk
;
152 unsigned int bus_hold_flag
;
154 struct notifier_block clk_rate_change_nb
;
157 #define to_cdns_i2c(_nb) container_of(_nb, struct cdns_i2c, \
161 * cdns_i2c_clear_bus_hold() - Clear bus hold bit
162 * @id: Pointer to driver data struct
164 * Helper to clear the controller's bus hold bit.
166 static void cdns_i2c_clear_bus_hold(struct cdns_i2c
*id
)
168 u32 reg
= cdns_i2c_readreg(CDNS_I2C_CR_OFFSET
);
169 if (reg
& CDNS_I2C_CR_HOLD
)
170 cdns_i2c_writereg(reg
& ~CDNS_I2C_CR_HOLD
, CDNS_I2C_CR_OFFSET
);
174 * cdns_i2c_isr - Interrupt handler for the I2C device
175 * @irq: irq number for the I2C device
176 * @ptr: void pointer to cdns_i2c structure
178 * This function handles the data interrupt, transfer complete interrupt and
179 * the error interrupts of the I2C device.
181 * Return: IRQ_HANDLED always
183 static irqreturn_t
cdns_i2c_isr(int irq
, void *ptr
)
185 unsigned int isr_status
, avail_bytes
;
186 unsigned int bytes_to_recv
, bytes_to_send
;
187 struct cdns_i2c
*id
= ptr
;
188 /* Signal completion only after everything is updated */
190 irqreturn_t status
= IRQ_NONE
;
192 isr_status
= cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET
);
194 /* Handling nack and arbitration lost interrupt */
195 if (isr_status
& (CDNS_I2C_IXR_NACK
| CDNS_I2C_IXR_ARB_LOST
)) {
197 status
= IRQ_HANDLED
;
200 /* Handling Data interrupt */
201 if ((isr_status
& CDNS_I2C_IXR_DATA
) &&
202 (id
->recv_count
>= CDNS_I2C_DATA_INTR_DEPTH
)) {
203 /* Always read data interrupt threshold bytes */
204 bytes_to_recv
= CDNS_I2C_DATA_INTR_DEPTH
;
205 id
->recv_count
-= CDNS_I2C_DATA_INTR_DEPTH
;
206 avail_bytes
= cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET
);
209 * if the tranfer size register value is zero, then
210 * check for the remaining bytes and update the
211 * transfer size register.
214 if (id
->recv_count
> CDNS_I2C_TRANSFER_SIZE
)
215 cdns_i2c_writereg(CDNS_I2C_TRANSFER_SIZE
,
216 CDNS_I2C_XFER_SIZE_OFFSET
);
218 cdns_i2c_writereg(id
->recv_count
,
219 CDNS_I2C_XFER_SIZE_OFFSET
);
222 /* Process the data received */
223 while (bytes_to_recv
--)
224 *(id
->p_recv_buf
)++ =
225 cdns_i2c_readreg(CDNS_I2C_DATA_OFFSET
);
227 if (!id
->bus_hold_flag
&&
228 (id
->recv_count
<= CDNS_I2C_FIFO_DEPTH
))
229 cdns_i2c_clear_bus_hold(id
);
231 status
= IRQ_HANDLED
;
234 /* Handling Transfer Complete interrupt */
235 if (isr_status
& CDNS_I2C_IXR_COMP
) {
236 if (!id
->p_recv_buf
) {
238 * If the device is sending data If there is further
239 * data to be sent. Calculate the available space
240 * in FIFO and fill the FIFO with that many bytes.
242 if (id
->send_count
) {
243 avail_bytes
= CDNS_I2C_FIFO_DEPTH
-
244 cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET
);
245 if (id
->send_count
> avail_bytes
)
246 bytes_to_send
= avail_bytes
;
248 bytes_to_send
= id
->send_count
;
250 while (bytes_to_send
--) {
252 (*(id
->p_send_buf
)++),
253 CDNS_I2C_DATA_OFFSET
);
258 * Signal the completion of transaction and
259 * clear the hold bus bit if there are no
260 * further messages to be processed.
264 if (!id
->send_count
&& !id
->bus_hold_flag
)
265 cdns_i2c_clear_bus_hold(id
);
267 if (!id
->bus_hold_flag
)
268 cdns_i2c_clear_bus_hold(id
);
270 * If the device is receiving data, then signal
271 * the completion of transaction and read the data
272 * present in the FIFO. Signal the completion of
275 while (cdns_i2c_readreg(CDNS_I2C_SR_OFFSET
) &
277 *(id
->p_recv_buf
)++ =
278 cdns_i2c_readreg(CDNS_I2C_DATA_OFFSET
);
284 status
= IRQ_HANDLED
;
287 /* Update the status for errors */
288 id
->err_status
= isr_status
& CDNS_I2C_IXR_ERR_INTR_MASK
;
290 status
= IRQ_HANDLED
;
292 cdns_i2c_writereg(isr_status
, CDNS_I2C_ISR_OFFSET
);
295 complete(&id
->xfer_done
);
301 * cdns_i2c_mrecv - Prepare and start a master receive operation
302 * @id: pointer to the i2c device structure
304 static void cdns_i2c_mrecv(struct cdns_i2c
*id
)
306 unsigned int ctrl_reg
;
307 unsigned int isr_status
;
309 id
->p_recv_buf
= id
->p_msg
->buf
;
310 id
->recv_count
= id
->p_msg
->len
;
312 /* Put the controller in master receive mode and clear the FIFO */
313 ctrl_reg
= cdns_i2c_readreg(CDNS_I2C_CR_OFFSET
);
314 ctrl_reg
|= CDNS_I2C_CR_RW
| CDNS_I2C_CR_CLR_FIFO
;
316 if (id
->p_msg
->flags
& I2C_M_RECV_LEN
)
317 id
->recv_count
= I2C_SMBUS_BLOCK_MAX
+ 1;
320 * Check for the message size against FIFO depth and set the
321 * 'hold bus' bit if it is greater than FIFO depth.
323 if (id
->recv_count
> CDNS_I2C_FIFO_DEPTH
)
324 ctrl_reg
|= CDNS_I2C_CR_HOLD
;
326 cdns_i2c_writereg(ctrl_reg
, CDNS_I2C_CR_OFFSET
);
328 /* Clear the interrupts in interrupt status register */
329 isr_status
= cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET
);
330 cdns_i2c_writereg(isr_status
, CDNS_I2C_ISR_OFFSET
);
333 * The no. of bytes to receive is checked against the limit of
334 * max transfer size. Set transfer size register with no of bytes
335 * receive if it is less than transfer size and transfer size if
336 * it is more. Enable the interrupts.
338 if (id
->recv_count
> CDNS_I2C_TRANSFER_SIZE
)
339 cdns_i2c_writereg(CDNS_I2C_TRANSFER_SIZE
,
340 CDNS_I2C_XFER_SIZE_OFFSET
);
342 cdns_i2c_writereg(id
->recv_count
, CDNS_I2C_XFER_SIZE_OFFSET
);
343 /* Clear the bus hold flag if bytes to receive is less than FIFO size */
344 if (!id
->bus_hold_flag
&&
345 ((id
->p_msg
->flags
& I2C_M_RECV_LEN
) != I2C_M_RECV_LEN
) &&
346 (id
->recv_count
<= CDNS_I2C_FIFO_DEPTH
))
347 cdns_i2c_clear_bus_hold(id
);
348 /* Set the slave address in address register - triggers operation */
349 cdns_i2c_writereg(id
->p_msg
->addr
& CDNS_I2C_ADDR_MASK
,
350 CDNS_I2C_ADDR_OFFSET
);
351 cdns_i2c_writereg(CDNS_I2C_ENABLED_INTR_MASK
, CDNS_I2C_IER_OFFSET
);
355 * cdns_i2c_msend - Prepare and start a master send operation
356 * @id: pointer to the i2c device
358 static void cdns_i2c_msend(struct cdns_i2c
*id
)
360 unsigned int avail_bytes
;
361 unsigned int bytes_to_send
;
362 unsigned int ctrl_reg
;
363 unsigned int isr_status
;
365 id
->p_recv_buf
= NULL
;
366 id
->p_send_buf
= id
->p_msg
->buf
;
367 id
->send_count
= id
->p_msg
->len
;
369 /* Set the controller in Master transmit mode and clear the FIFO. */
370 ctrl_reg
= cdns_i2c_readreg(CDNS_I2C_CR_OFFSET
);
371 ctrl_reg
&= ~CDNS_I2C_CR_RW
;
372 ctrl_reg
|= CDNS_I2C_CR_CLR_FIFO
;
375 * Check for the message size against FIFO depth and set the
376 * 'hold bus' bit if it is greater than FIFO depth.
378 if (id
->send_count
> CDNS_I2C_FIFO_DEPTH
)
379 ctrl_reg
|= CDNS_I2C_CR_HOLD
;
380 cdns_i2c_writereg(ctrl_reg
, CDNS_I2C_CR_OFFSET
);
382 /* Clear the interrupts in interrupt status register. */
383 isr_status
= cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET
);
384 cdns_i2c_writereg(isr_status
, CDNS_I2C_ISR_OFFSET
);
387 * Calculate the space available in FIFO. Check the message length
388 * against the space available, and fill the FIFO accordingly.
389 * Enable the interrupts.
391 avail_bytes
= CDNS_I2C_FIFO_DEPTH
-
392 cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET
);
394 if (id
->send_count
> avail_bytes
)
395 bytes_to_send
= avail_bytes
;
397 bytes_to_send
= id
->send_count
;
399 while (bytes_to_send
--) {
400 cdns_i2c_writereg((*(id
->p_send_buf
)++), CDNS_I2C_DATA_OFFSET
);
405 * Clear the bus hold flag if there is no more data
406 * and if it is the last message.
408 if (!id
->bus_hold_flag
&& !id
->send_count
)
409 cdns_i2c_clear_bus_hold(id
);
410 /* Set the slave address in address register - triggers operation. */
411 cdns_i2c_writereg(id
->p_msg
->addr
& CDNS_I2C_ADDR_MASK
,
412 CDNS_I2C_ADDR_OFFSET
);
414 cdns_i2c_writereg(CDNS_I2C_ENABLED_INTR_MASK
, CDNS_I2C_IER_OFFSET
);
418 * cdns_i2c_master_reset - Reset the interface
419 * @adap: pointer to the i2c adapter driver instance
421 * This function cleanup the fifos, clear the hold bit and status
422 * and disable the interrupts.
424 static void cdns_i2c_master_reset(struct i2c_adapter
*adap
)
426 struct cdns_i2c
*id
= adap
->algo_data
;
429 /* Disable the interrupts */
430 cdns_i2c_writereg(CDNS_I2C_IXR_ALL_INTR_MASK
, CDNS_I2C_IDR_OFFSET
);
431 /* Clear the hold bit and fifos */
432 regval
= cdns_i2c_readreg(CDNS_I2C_CR_OFFSET
);
433 regval
&= ~CDNS_I2C_CR_HOLD
;
434 regval
|= CDNS_I2C_CR_CLR_FIFO
;
435 cdns_i2c_writereg(regval
, CDNS_I2C_CR_OFFSET
);
436 /* Update the transfercount register to zero */
437 cdns_i2c_writereg(0, CDNS_I2C_XFER_SIZE_OFFSET
);
438 /* Clear the interupt status register */
439 regval
= cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET
);
440 cdns_i2c_writereg(regval
, CDNS_I2C_ISR_OFFSET
);
441 /* Clear the status register */
442 regval
= cdns_i2c_readreg(CDNS_I2C_SR_OFFSET
);
443 cdns_i2c_writereg(regval
, CDNS_I2C_SR_OFFSET
);
446 static int cdns_i2c_process_msg(struct cdns_i2c
*id
, struct i2c_msg
*msg
,
447 struct i2c_adapter
*adap
)
454 reinit_completion(&id
->xfer_done
);
456 /* Check for the TEN Bit mode on each msg */
457 reg
= cdns_i2c_readreg(CDNS_I2C_CR_OFFSET
);
458 if (msg
->flags
& I2C_M_TEN
) {
459 if (reg
& CDNS_I2C_CR_NEA
)
460 cdns_i2c_writereg(reg
& ~CDNS_I2C_CR_NEA
,
463 if (!(reg
& CDNS_I2C_CR_NEA
))
464 cdns_i2c_writereg(reg
| CDNS_I2C_CR_NEA
,
468 /* Check for the R/W flag on each msg */
469 if (msg
->flags
& I2C_M_RD
)
474 /* Wait for the signal of completion */
475 ret
= wait_for_completion_timeout(&id
->xfer_done
, adap
->timeout
);
477 cdns_i2c_master_reset(adap
);
478 dev_err(id
->adap
.dev
.parent
,
479 "timeout waiting on completion\n");
483 cdns_i2c_writereg(CDNS_I2C_IXR_ALL_INTR_MASK
,
484 CDNS_I2C_IDR_OFFSET
);
486 /* If it is bus arbitration error, try again */
487 if (id
->err_status
& CDNS_I2C_IXR_ARB_LOST
)
494 * cdns_i2c_master_xfer - The main i2c transfer function
495 * @adap: pointer to the i2c adapter driver instance
496 * @msgs: pointer to the i2c message structure
497 * @num: the number of messages to transfer
499 * Initiates the send/recv activity based on the transfer message received.
501 * Return: number of msgs processed on success, negative error otherwise
503 static int cdns_i2c_master_xfer(struct i2c_adapter
*adap
, struct i2c_msg
*msgs
,
508 struct cdns_i2c
*id
= adap
->algo_data
;
510 /* Check if the bus is free */
511 if (cdns_i2c_readreg(CDNS_I2C_SR_OFFSET
) & CDNS_I2C_SR_BA
)
515 * Set the flag to one when multiple messages are to be
516 * processed with a repeated start.
519 id
->bus_hold_flag
= 1;
520 reg
= cdns_i2c_readreg(CDNS_I2C_CR_OFFSET
);
521 reg
|= CDNS_I2C_CR_HOLD
;
522 cdns_i2c_writereg(reg
, CDNS_I2C_CR_OFFSET
);
524 id
->bus_hold_flag
= 0;
527 /* Process the msg one by one */
528 for (count
= 0; count
< num
; count
++, msgs
++) {
529 if (count
== (num
- 1))
530 id
->bus_hold_flag
= 0;
532 ret
= cdns_i2c_process_msg(id
, msgs
, adap
);
536 /* Report the other error interrupts to application */
537 if (id
->err_status
) {
538 cdns_i2c_master_reset(adap
);
540 if (id
->err_status
& CDNS_I2C_IXR_NACK
)
551 * cdns_i2c_func - Returns the supported features of the I2C driver
552 * @adap: pointer to the i2c adapter structure
554 * Return: 32 bit value, each bit corresponding to a feature
556 static u32
cdns_i2c_func(struct i2c_adapter
*adap
)
558 return I2C_FUNC_I2C
| I2C_FUNC_10BIT_ADDR
|
559 (I2C_FUNC_SMBUS_EMUL
& ~I2C_FUNC_SMBUS_QUICK
) |
560 I2C_FUNC_SMBUS_BLOCK_DATA
;
563 static const struct i2c_algorithm cdns_i2c_algo
= {
564 .master_xfer
= cdns_i2c_master_xfer
,
565 .functionality
= cdns_i2c_func
,
569 * cdns_i2c_calc_divs - Calculate clock dividers
570 * @f: I2C clock frequency
571 * @input_clk: Input clock frequency
572 * @a: First divider (return value)
573 * @b: Second divider (return value)
575 * f is used as input and output variable. As input it is used as target I2C
576 * frequency. On function exit f holds the actually resulting I2C frequency.
578 * Return: 0 on success, negative errno otherwise.
580 static int cdns_i2c_calc_divs(unsigned long *f
, unsigned long input_clk
,
581 unsigned int *a
, unsigned int *b
)
583 unsigned long fscl
= *f
, best_fscl
= *f
, actual_fscl
, temp
;
584 unsigned int div_a
, div_b
, calc_div_a
= 0, calc_div_b
= 0;
585 unsigned int last_error
, current_error
;
587 /* calculate (divisor_a+1) x (divisor_b+1) */
588 temp
= input_clk
/ (22 * fscl
);
591 * If the calculated value is negative or 0, the fscl input is out of
592 * range. Return error.
594 if (!temp
|| (temp
> (CDNS_I2C_DIVA_MAX
* CDNS_I2C_DIVB_MAX
)))
598 for (div_a
= 0; div_a
< CDNS_I2C_DIVA_MAX
; div_a
++) {
599 div_b
= DIV_ROUND_UP(input_clk
, 22 * fscl
* (div_a
+ 1));
601 if ((div_b
< 1) || (div_b
> CDNS_I2C_DIVB_MAX
))
605 actual_fscl
= input_clk
/ (22 * (div_a
+ 1) * (div_b
+ 1));
607 if (actual_fscl
> fscl
)
610 current_error
= ((actual_fscl
> fscl
) ? (actual_fscl
- fscl
) :
611 (fscl
- actual_fscl
));
613 if (last_error
> current_error
) {
616 best_fscl
= actual_fscl
;
617 last_error
= current_error
;
629 * cdns_i2c_setclk - This function sets the serial clock rate for the I2C device
630 * @clk_in: I2C clock input frequency in Hz
631 * @id: Pointer to the I2C device structure
633 * The device must be idle rather than busy transferring data before setting
634 * these device options.
635 * The data rate is set by values in the control register.
636 * The formula for determining the correct register values is
637 * Fscl = Fpclk/(22 x (divisor_a+1) x (divisor_b+1))
638 * See the hardware data sheet for a full explanation of setting the serial
639 * clock rate. The clock can not be faster than the input clock divide by 22.
640 * The two most common clock rates are 100KHz and 400KHz.
642 * Return: 0 on success, negative error otherwise
644 static int cdns_i2c_setclk(unsigned long clk_in
, struct cdns_i2c
*id
)
646 unsigned int div_a
, div_b
;
647 unsigned int ctrl_reg
;
649 unsigned long fscl
= id
->i2c_clk
;
651 ret
= cdns_i2c_calc_divs(&fscl
, clk_in
, &div_a
, &div_b
);
655 ctrl_reg
= cdns_i2c_readreg(CDNS_I2C_CR_OFFSET
);
656 ctrl_reg
&= ~(CDNS_I2C_CR_DIVA_MASK
| CDNS_I2C_CR_DIVB_MASK
);
657 ctrl_reg
|= ((div_a
<< CDNS_I2C_CR_DIVA_SHIFT
) |
658 (div_b
<< CDNS_I2C_CR_DIVB_SHIFT
));
659 cdns_i2c_writereg(ctrl_reg
, CDNS_I2C_CR_OFFSET
);
665 * cdns_i2c_clk_notifier_cb - Clock rate change callback
666 * @nb: Pointer to notifier block
667 * @event: Notification reason
668 * @data: Pointer to notification data object
670 * This function is called when the cdns_i2c input clock frequency changes.
671 * The callback checks whether a valid bus frequency can be generated after the
672 * change. If so, the change is acknowledged, otherwise the change is aborted.
673 * New dividers are written to the HW in the pre- or post change notification
674 * depending on the scaling direction.
676 * Return: NOTIFY_STOP if the rate change should be aborted, NOTIFY_OK
677 * to acknowedge the change, NOTIFY_DONE if the notification is
678 * considered irrelevant.
680 static int cdns_i2c_clk_notifier_cb(struct notifier_block
*nb
, unsigned long
683 struct clk_notifier_data
*ndata
= data
;
684 struct cdns_i2c
*id
= to_cdns_i2c(nb
);
690 case PRE_RATE_CHANGE
:
692 unsigned long input_clk
= ndata
->new_rate
;
693 unsigned long fscl
= id
->i2c_clk
;
694 unsigned int div_a
, div_b
;
697 ret
= cdns_i2c_calc_divs(&fscl
, input_clk
, &div_a
, &div_b
);
699 dev_warn(id
->adap
.dev
.parent
,
700 "clock rate change rejected\n");
705 if (ndata
->new_rate
> ndata
->old_rate
)
706 cdns_i2c_setclk(ndata
->new_rate
, id
);
710 case POST_RATE_CHANGE
:
711 id
->input_clk
= ndata
->new_rate
;
713 if (ndata
->new_rate
< ndata
->old_rate
)
714 cdns_i2c_setclk(ndata
->new_rate
, id
);
716 case ABORT_RATE_CHANGE
:
718 if (ndata
->new_rate
> ndata
->old_rate
)
719 cdns_i2c_setclk(ndata
->old_rate
, id
);
727 * cdns_i2c_suspend - Suspend method for the driver
728 * @_dev: Address of the platform_device structure
730 * Put the driver into low power mode.
734 static int __maybe_unused
cdns_i2c_suspend(struct device
*_dev
)
736 struct platform_device
*pdev
= container_of(_dev
,
737 struct platform_device
, dev
);
738 struct cdns_i2c
*xi2c
= platform_get_drvdata(pdev
);
740 clk_disable(xi2c
->clk
);
747 * cdns_i2c_resume - Resume from suspend
748 * @_dev: Address of the platform_device structure
750 * Resume operation after suspend.
752 * Return: 0 on success and error value on error
754 static int __maybe_unused
cdns_i2c_resume(struct device
*_dev
)
756 struct platform_device
*pdev
= container_of(_dev
,
757 struct platform_device
, dev
);
758 struct cdns_i2c
*xi2c
= platform_get_drvdata(pdev
);
761 ret
= clk_enable(xi2c
->clk
);
763 dev_err(_dev
, "Cannot enable clock.\n");
772 static SIMPLE_DEV_PM_OPS(cdns_i2c_dev_pm_ops
, cdns_i2c_suspend
,
776 * cdns_i2c_probe - Platform registration call
777 * @pdev: Handle to the platform device structure
779 * This function does all the memory allocation and registration for the i2c
780 * device. User can modify the address mode to 10 bit address mode using the
781 * ioctl call with option I2C_TENBIT.
783 * Return: 0 on success, negative error otherwise
785 static int cdns_i2c_probe(struct platform_device
*pdev
)
787 struct resource
*r_mem
;
791 id
= devm_kzalloc(&pdev
->dev
, sizeof(*id
), GFP_KERNEL
);
795 platform_set_drvdata(pdev
, id
);
797 r_mem
= platform_get_resource(pdev
, IORESOURCE_MEM
, 0);
798 id
->membase
= devm_ioremap_resource(&pdev
->dev
, r_mem
);
799 if (IS_ERR(id
->membase
))
800 return PTR_ERR(id
->membase
);
802 id
->irq
= platform_get_irq(pdev
, 0);
804 id
->adap
.dev
.of_node
= pdev
->dev
.of_node
;
805 id
->adap
.algo
= &cdns_i2c_algo
;
806 id
->adap
.timeout
= CDNS_I2C_TIMEOUT
;
807 id
->adap
.retries
= 3; /* Default retry value. */
808 id
->adap
.algo_data
= id
;
809 id
->adap
.dev
.parent
= &pdev
->dev
;
810 init_completion(&id
->xfer_done
);
811 snprintf(id
->adap
.name
, sizeof(id
->adap
.name
),
812 "Cadence I2C at %08lx", (unsigned long)r_mem
->start
);
814 id
->clk
= devm_clk_get(&pdev
->dev
, NULL
);
815 if (IS_ERR(id
->clk
)) {
816 dev_err(&pdev
->dev
, "input clock not found.\n");
817 return PTR_ERR(id
->clk
);
819 ret
= clk_prepare_enable(id
->clk
);
821 dev_err(&pdev
->dev
, "Unable to enable clock.\n");
824 id
->clk_rate_change_nb
.notifier_call
= cdns_i2c_clk_notifier_cb
;
825 if (clk_notifier_register(id
->clk
, &id
->clk_rate_change_nb
))
826 dev_warn(&pdev
->dev
, "Unable to register clock notifier.\n");
827 id
->input_clk
= clk_get_rate(id
->clk
);
829 ret
= of_property_read_u32(pdev
->dev
.of_node
, "clock-frequency",
831 if (ret
|| (id
->i2c_clk
> CDNS_I2C_SPEED_MAX
))
832 id
->i2c_clk
= CDNS_I2C_SPEED_DEFAULT
;
834 cdns_i2c_writereg(CDNS_I2C_CR_ACK_EN
| CDNS_I2C_CR_NEA
| CDNS_I2C_CR_MS
,
837 ret
= cdns_i2c_setclk(id
->input_clk
, id
);
839 dev_err(&pdev
->dev
, "invalid SCL clock: %u Hz\n", id
->i2c_clk
);
844 ret
= devm_request_irq(&pdev
->dev
, id
->irq
, cdns_i2c_isr
, 0,
847 dev_err(&pdev
->dev
, "cannot get irq %d\n", id
->irq
);
851 ret
= i2c_add_adapter(&id
->adap
);
853 dev_err(&pdev
->dev
, "reg adap failed: %d\n", ret
);
858 * Cadence I2C controller has a bug wherein it generates
859 * invalid read transaction after HW timeout in master receiver mode.
860 * HW timeout is not used by this driver and the interrupt is disabled.
861 * But the feature itself cannot be disabled. Hence maximum value
862 * is written to this register to reduce the chances of error.
864 cdns_i2c_writereg(CDNS_I2C_TIMEOUT_MAX
, CDNS_I2C_TIME_OUT_OFFSET
);
866 dev_info(&pdev
->dev
, "%u kHz mmio %08lx irq %d\n",
867 id
->i2c_clk
/ 1000, (unsigned long)r_mem
->start
, id
->irq
);
872 clk_disable_unprepare(id
->clk
);
877 * cdns_i2c_remove - Unregister the device after releasing the resources
878 * @pdev: Handle to the platform device structure
880 * This function frees all the resources allocated to the device.
884 static int cdns_i2c_remove(struct platform_device
*pdev
)
886 struct cdns_i2c
*id
= platform_get_drvdata(pdev
);
888 i2c_del_adapter(&id
->adap
);
889 clk_notifier_unregister(id
->clk
, &id
->clk_rate_change_nb
);
890 clk_disable_unprepare(id
->clk
);
895 static const struct of_device_id cdns_i2c_of_match
[] = {
896 { .compatible
= "cdns,i2c-r1p10", },
897 { /* end of table */ }
899 MODULE_DEVICE_TABLE(of
, cdns_i2c_of_match
);
901 static struct platform_driver cdns_i2c_drv
= {
904 .owner
= THIS_MODULE
,
905 .of_match_table
= cdns_i2c_of_match
,
906 .pm
= &cdns_i2c_dev_pm_ops
,
908 .probe
= cdns_i2c_probe
,
909 .remove
= cdns_i2c_remove
,
912 module_platform_driver(cdns_i2c_drv
);
914 MODULE_AUTHOR("Xilinx Inc.");
915 MODULE_DESCRIPTION("Cadence I2C bus driver");
916 MODULE_LICENSE("GPL");