2 * Driver for the TWSI (i2c) controller found on the Marvell
3 * orion5x and kirkwood SoC families.
5 * Author: Albert Aribaud <albert.u.boot@aribaud.net>
6 * Copyright (c) 2010 Albert Aribaud.
8 * SPDX-License-Identifier: GPL-2.0+
13 #include <asm/errno.h>
17 * include a file that will provide CONFIG_I2C_MVTWSI_BASE
18 * and possibly other settings
21 #if defined(CONFIG_ORION5X)
22 #include <asm/arch/orion5x.h>
23 #elif defined(CONFIG_KIRKWOOD)
24 #include <asm/arch/kirkwood.h>
25 #elif defined(CONFIG_SUNXI)
26 #include <asm/arch/i2c.h>
28 #error Driver mvtwsi not supported by SoC or board
32 * TWSI register structure
37 struct mvtwsi_registers
{
49 struct mvtwsi_registers
{
54 u32 status
; /* when reading */
55 u32 baudrate
; /* when writing */
65 * Control register fields
68 #define MVTWSI_CONTROL_ACK 0x00000004
69 #define MVTWSI_CONTROL_IFLG 0x00000008
70 #define MVTWSI_CONTROL_STOP 0x00000010
71 #define MVTWSI_CONTROL_START 0x00000020
72 #define MVTWSI_CONTROL_TWSIEN 0x00000040
73 #define MVTWSI_CONTROL_INTEN 0x00000080
76 * Status register values -- only those expected in normal master
77 * operation on non-10-bit-address devices; whatever status we don't
78 * expect in nominal conditions (bus errors, arbitration losses,
79 * missing ACKs...) we just pass back to the caller as an error
83 #define MVTWSI_STATUS_START 0x08
84 #define MVTWSI_STATUS_REPEATED_START 0x10
85 #define MVTWSI_STATUS_ADDR_W_ACK 0x18
86 #define MVTWSI_STATUS_DATA_W_ACK 0x28
87 #define MVTWSI_STATUS_ADDR_R_ACK 0x40
88 #define MVTWSI_STATUS_ADDR_R_NAK 0x48
89 #define MVTWSI_STATUS_DATA_R_ACK 0x50
90 #define MVTWSI_STATUS_DATA_R_NAK 0x58
91 #define MVTWSI_STATUS_IDLE 0xF8
94 * The single instance of the controller we'll be dealing with
97 static struct mvtwsi_registers
*twsi
=
98 (struct mvtwsi_registers
*) CONFIG_I2C_MVTWSI_BASE
;
101 * Returned statuses are 0 for success and nonzero otherwise.
102 * Currently, cmd_i2c and cmd_eeprom do not interpret an error status.
103 * Thus to ease debugging, the return status contains some debug info:
104 * - bits 31..24 are error class: 1 is timeout, 2 is 'status mismatch'.
105 * - bits 23..16 are the last value of the control register.
106 * - bits 15..8 are the last value of the status register.
107 * - bits 7..0 are the expected value of the status register.
110 #define MVTWSI_ERROR_WRONG_STATUS 0x01
111 #define MVTWSI_ERROR_TIMEOUT 0x02
113 #define MVTWSI_ERROR(ec, lc, ls, es) (((ec << 24) & 0xFF000000) | \
114 ((lc << 16) & 0x00FF0000) | ((ls<<8) & 0x0000FF00) | (es & 0xFF))
117 * Wait for IFLG to raise, or return 'timeout'; then if status is as expected,
118 * return 0 (ok) or return 'wrong status'.
120 static int twsi_wait(int expected_status
)
126 control
= readl(&twsi
->control
);
127 if (control
& MVTWSI_CONTROL_IFLG
) {
128 status
= readl(&twsi
->status
);
129 if (status
== expected_status
)
133 MVTWSI_ERROR_WRONG_STATUS
,
134 control
, status
, expected_status
);
136 udelay(10); /* one clock cycle at 100 kHz */
138 status
= readl(&twsi
->status
);
140 MVTWSI_ERROR_TIMEOUT
, control
, status
, expected_status
);
144 * These flags are ORed to any write to the control register
145 * They allow global setting of TWSIEN and ACK.
146 * By default none are set.
147 * twsi_start() sets TWSIEN (in case the controller was disabled)
148 * twsi_recv() sets ACK or resets it depending on expected status.
150 static u8 twsi_control_flags
= MVTWSI_CONTROL_TWSIEN
;
153 * Assert the START condition, either in a single I2C transaction
154 * or inside back-to-back ones (repeated starts).
156 static int twsi_start(int expected_status
)
158 /* globally set TWSIEN in case it was not */
159 twsi_control_flags
|= MVTWSI_CONTROL_TWSIEN
;
161 writel(twsi_control_flags
| MVTWSI_CONTROL_START
, &twsi
->control
);
162 /* wait for controller to process START */
163 return twsi_wait(expected_status
);
167 * Send a byte (i2c address or data).
169 static int twsi_send(u8 byte
, int expected_status
)
171 /* put byte in data register for sending */
172 writel(byte
, &twsi
->data
);
173 /* clear any pending interrupt -- that'll cause sending */
174 writel(twsi_control_flags
, &twsi
->control
);
175 /* wait for controller to receive byte and check ACK */
176 return twsi_wait(expected_status
);
181 * Global mvtwsi_control_flags variable says if we should ack or nak.
183 static int twsi_recv(u8
*byte
)
185 int expected_status
, status
;
187 /* compute expected status based on ACK bit in global control flags */
188 if (twsi_control_flags
& MVTWSI_CONTROL_ACK
)
189 expected_status
= MVTWSI_STATUS_DATA_R_ACK
;
191 expected_status
= MVTWSI_STATUS_DATA_R_NAK
;
192 /* acknowledge *previous state* and launch receive */
193 writel(twsi_control_flags
, &twsi
->control
);
194 /* wait for controller to receive byte and assert ACK or NAK */
195 status
= twsi_wait(expected_status
);
196 /* if we did receive expected byte then store it */
198 *byte
= readl(&twsi
->data
);
204 * Assert the STOP condition.
205 * This is also used to force the bus back in idle (SDA=SCL=1).
207 static int twsi_stop(int status
)
209 int control
, stop_status
;
213 control
= MVTWSI_CONTROL_TWSIEN
| MVTWSI_CONTROL_STOP
;
214 writel(control
, &twsi
->control
);
215 /* wait for IDLE; IFLG won't rise so twsi_wait() is no use. */
217 stop_status
= readl(&twsi
->status
);
218 if (stop_status
== MVTWSI_STATUS_IDLE
)
220 udelay(10); /* one clock cycle at 100 kHz */
222 control
= readl(&twsi
->control
);
223 if (stop_status
!= MVTWSI_STATUS_IDLE
)
225 status
= MVTWSI_ERROR(
226 MVTWSI_ERROR_TIMEOUT
,
227 control
, status
, MVTWSI_STATUS_IDLE
);
232 * Ugly formula to convert m and n values to a frequency comes from
233 * TWSI specifications
236 #define TWSI_FREQUENCY(m, n) \
237 (CONFIG_SYS_TCLK / (10 * (m + 1) * (1 << n)))
241 * Controller reset also resets the baud rate and slave address, so
242 * they must be re-established afterwards.
244 static void twsi_reset(struct i2c_adapter
*adap
)
246 /* ensure controller will be enabled by any twsi*() function */
247 twsi_control_flags
= MVTWSI_CONTROL_TWSIEN
;
248 /* reset controller */
249 writel(0, &twsi
->soft_reset
);
250 /* wait 2 ms -- this is what the Marvell LSP does */
255 * I2C init called by cmd_i2c when doing 'i2c reset'.
256 * Sets baud to the highest possible value not exceeding requested one.
258 static unsigned int twsi_i2c_set_bus_speed(struct i2c_adapter
*adap
,
259 unsigned int requested_speed
)
261 unsigned int tmp_speed
, highest_speed
, n
, m
;
262 unsigned int baud
= 0x44; /* baudrate at controller reset */
264 /* use actual speed to collect progressively higher values */
266 /* compute m, n setting for highest speed not above requested speed */
267 for (n
= 0; n
< 8; n
++) {
268 for (m
= 0; m
< 16; m
++) {
269 tmp_speed
= TWSI_FREQUENCY(m
, n
);
270 if ((tmp_speed
<= requested_speed
)
271 && (tmp_speed
> highest_speed
)) {
272 highest_speed
= tmp_speed
;
277 writel(baud
, &twsi
->baudrate
);
281 static void twsi_i2c_init(struct i2c_adapter
*adap
, int speed
, int slaveadd
)
283 /* reset controller */
286 twsi_i2c_set_bus_speed(adap
, speed
);
287 /* set slave address even though we don't use it */
288 writel(slaveadd
, &twsi
->slave_address
);
289 writel(0, &twsi
->xtnd_slave_addr
);
290 /* assert STOP but don't care for the result */
295 * Begin I2C transaction with expected start status, at given address.
296 * Common to i2c_probe, i2c_read and i2c_write.
297 * Expected address status will derive from direction bit (bit 0) in addr.
299 static int i2c_begin(int expected_start_status
, u8 addr
)
301 int status
, expected_addr_status
;
303 /* compute expected address status from direction bit in addr */
304 if (addr
& 1) /* reading */
305 expected_addr_status
= MVTWSI_STATUS_ADDR_R_ACK
;
307 expected_addr_status
= MVTWSI_STATUS_ADDR_W_ACK
;
309 status
= twsi_start(expected_start_status
);
310 /* send out the address if the start went well */
312 status
= twsi_send(addr
, expected_addr_status
);
313 /* return ok or status of first failure to caller */
318 * I2C probe called by cmd_i2c when doing 'i2c probe'.
319 * Begin read, nak data byte, end.
321 static int twsi_i2c_probe(struct i2c_adapter
*adap
, uchar chip
)
327 status
= i2c_begin(MVTWSI_STATUS_START
, (chip
<< 1) | 1);
328 /* dummy read was accepted: receive byte but NAK it. */
330 status
= twsi_recv(&dummy_byte
);
331 /* Stop transaction */
333 /* return 0 or status of first failure */
338 * I2C read called by cmd_i2c when doing 'i2c read' and by cmd_eeprom.c
339 * Begin write, send address byte(s), begin read, receive data bytes, end.
341 * NOTE: some EEPROMS want a stop right before the second start, while
342 * some will choke if it is there. Deciding which we should do is eeprom
343 * stuff, not i2c, but at the moment the APIs won't let us put it in
344 * cmd_eeprom, so we have to choose here, and for the moment that'll be
345 * a repeated start without a preceding stop.
347 static int twsi_i2c_read(struct i2c_adapter
*adap
, uchar chip
, uint addr
,
348 int alen
, uchar
*data
, int length
)
352 /* begin i2c write to send the address bytes */
353 status
= i2c_begin(MVTWSI_STATUS_START
, (chip
<< 1));
354 /* send addr bytes */
355 while ((status
== 0) && alen
--)
356 status
= twsi_send(addr
>> (8*alen
),
357 MVTWSI_STATUS_DATA_W_ACK
);
358 /* begin i2c read to receive eeprom data bytes */
361 MVTWSI_STATUS_REPEATED_START
, (chip
<< 1) | 1);
362 /* prepare ACK if at least one byte must be received */
364 twsi_control_flags
|= MVTWSI_CONTROL_ACK
;
365 /* now receive actual bytes */
366 while ((status
== 0) && length
--) {
367 /* reset NAK if we if no more to read now */
369 twsi_control_flags
&= ~MVTWSI_CONTROL_ACK
;
370 /* read current byte */
371 status
= twsi_recv(data
++);
373 /* Stop transaction */
374 status
= twsi_stop(status
);
375 /* return 0 or status of first failure */
380 * I2C write called by cmd_i2c when doing 'i2c write' and by cmd_eeprom.c
381 * Begin write, send address byte(s), send data bytes, end.
383 static int twsi_i2c_write(struct i2c_adapter
*adap
, uchar chip
, uint addr
,
384 int alen
, uchar
*data
, int length
)
388 /* begin i2c write to send the eeprom adress bytes then data bytes */
389 status
= i2c_begin(MVTWSI_STATUS_START
, (chip
<< 1));
390 /* send addr bytes */
391 while ((status
== 0) && alen
--)
392 status
= twsi_send(addr
>> (8*alen
),
393 MVTWSI_STATUS_DATA_W_ACK
);
394 /* send data bytes */
395 while ((status
== 0) && (length
-- > 0))
396 status
= twsi_send(*(data
++), MVTWSI_STATUS_DATA_W_ACK
);
397 /* Stop transaction */
398 status
= twsi_stop(status
);
399 /* return 0 or status of first failure */
403 U_BOOT_I2C_ADAP_COMPLETE(twsi0
, twsi_i2c_init
, twsi_i2c_probe
,
404 twsi_i2c_read
, twsi_i2c_write
,
405 twsi_i2c_set_bus_speed
,
406 CONFIG_SYS_I2C_SPEED
, CONFIG_SYS_I2C_SLAVE
, 0)