Skip to content

Commit e789029

Browse files
lyakhwsakernel
lyakh
authored and
wsakernel
committed
i2c: sh_mobile: don't send a stop condition by default inside transfers
By default there should be no stop bit on I2C between single messages within transfers. Fix the driver to comply and only send a stop bit at the end of transfers or if I2C_M_STOP is set. Signed-off-by: Guennadi Liakhovetski <[email protected]> Signed-off-by: Wolfram Sang <[email protected]>
1 parent 4b38231 commit e789029

File tree

1 file changed

+59
-20
lines changed

1 file changed

+59
-20
lines changed

‎drivers/i2c/busses/i2c-sh_mobile.c‎

Lines changed: 59 additions & 20 deletions
Original file line numberDiff line numberDiff line change
@@ -38,21 +38,21 @@
3838
/* Transmit operation: */
3939
/* */
4040
/* 0 byte transmit */
41-
/* BUS: S A8 ACK P */
41+
/* BUS: S A8 ACK P(*) */
4242
/* IRQ: DTE WAIT */
4343
/* ICIC: */
4444
/* ICCR: 0x94 0x90 */
4545
/* ICDR: A8 */
4646
/* */
4747
/* 1 byte transmit */
48-
/* BUS: S A8 ACK D8(1) ACK P */
48+
/* BUS: S A8 ACK D8(1) ACK P(*) */
4949
/* IRQ: DTE WAIT WAIT */
5050
/* ICIC: -DTE */
5151
/* ICCR: 0x94 0x90 */
5252
/* ICDR: A8 D8(1) */
5353
/* */
5454
/* 2 byte transmit */
55-
/* BUS: S A8 ACK D8(1) ACK D8(2) ACK P */
55+
/* BUS: S A8 ACK D8(1) ACK D8(2) ACK P(*) */
5656
/* IRQ: DTE WAIT WAIT WAIT */
5757
/* ICIC: -DTE */
5858
/* ICCR: 0x94 0x90 */
@@ -66,20 +66,20 @@
6666
/* 0 byte receive - not supported since slave may hold SDA low */
6767
/* */
6868
/* 1 byte receive [TX] | [RX] */
69-
/* BUS: S A8 ACK | D8(1) ACK P */
69+
/* BUS: S A8 ACK | D8(1) ACK P(*) */
7070
/* IRQ: DTE WAIT | WAIT DTE */
7171
/* ICIC: -DTE | +DTE */
7272
/* ICCR: 0x94 0x81 | 0xc0 */
7373
/* ICDR: A8 | D8(1) */
7474
/* */
7575
/* 2 byte receive [TX]| [RX] */
76-
/* BUS: S A8 ACK | D8(1) ACK D8(2) ACK P */
76+
/* BUS: S A8 ACK | D8(1) ACK D8(2) ACK P(*) */
7777
/* IRQ: DTE WAIT | WAIT WAIT DTE */
7878
/* ICIC: -DTE | +DTE */
7979
/* ICCR: 0x94 0x81 | 0xc0 */
8080
/* ICDR: A8 | D8(1) D8(2) */
8181
/* */
82-
/* 3 byte receive [TX] | [RX] */
82+
/* 3 byte receive [TX] | [RX] (*) */
8383
/* BUS: S A8 ACK | D8(1) ACK D8(2) ACK D8(3) ACK P */
8484
/* IRQ: DTE WAIT | WAIT WAIT WAIT DTE */
8585
/* ICIC: -DTE | +DTE */
@@ -94,7 +94,7 @@
9494
/* SDA ___\___XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXAAAAAAAAA___/ */
9595
/* SCL \_/1\_/2\_/3\_/4\_/5\_/6\_/7\_/8\___/9\_____/ */
9696
/* */
97-
/* S D7 D6 D5 D4 D3 D2 D1 D0 P */
97+
/* S D7 D6 D5 D4 D3 D2 D1 D0 P(*) */
9898
/* ___ */
9999
/* WAIT IRQ ________________________________/ \___________ */
100100
/* TACK IRQ ____________________________________/ \_______ */
@@ -103,6 +103,11 @@
103103
/* _______________________________________________ */
104104
/* BUSY __/ \_ */
105105
/* */
106+
/* (*) The STOP condition is only sent by the master at the end of the last */
107+
/* I2C message or if the I2C_M_STOP flag is set. Similarly, the BUSY bit is */
108+
/* only cleared after the STOP condition, so, between messages we have to */
109+
/* poll for the DTE bit. */
110+
/* */
106111

107112
enum sh_mobile_i2c_op {
108113
OP_START = 0,
@@ -132,6 +137,7 @@ struct sh_mobile_i2c_data {
132137
struct i2c_msg *msg;
133138
int pos;
134139
int sr;
140+
bool send_stop;
135141
};
136142

137143
#define IIC_FLAG_HAS_ICIC67 (1 << 0)
@@ -322,7 +328,7 @@ static unsigned char i2c_op(struct sh_mobile_i2c_data *pd,
322328
break;
323329
case OP_TX_STOP: /* write data and issue a stop afterwards */
324330
iic_wr(pd, ICDR, data);
325-
iic_wr(pd, ICCR, 0x90);
331+
iic_wr(pd, ICCR, pd->send_stop ? 0x90 : 0x94);
326332
break;
327333
case OP_TX_TO_RX: /* select read mode */
328334
iic_wr(pd, ICCR, 0x81);
@@ -469,22 +475,25 @@ static irqreturn_t sh_mobile_i2c_isr(int irq, void *dev_id)
469475
return IRQ_HANDLED;
470476
}
471477

472-
static int start_ch(struct sh_mobile_i2c_data *pd, struct i2c_msg *usr_msg)
478+
static int start_ch(struct sh_mobile_i2c_data *pd, struct i2c_msg *usr_msg,
479+
bool do_init)
473480
{
474481
if (usr_msg->len == 0 && (usr_msg->flags & I2C_M_RD)) {
475482
dev_err(pd->dev, "Unsupported zero length i2c read\n");
476483
return -EIO;
477484
}
478485

479-
/* Initialize channel registers */
480-
iic_set_clr(pd, ICCR, 0, ICCR_ICE);
486+
if (do_init) {
487+
/* Initialize channel registers */
488+
iic_set_clr(pd, ICCR, 0, ICCR_ICE);
481489

482-
/* Enable channel and configure rx ack */
483-
iic_set_clr(pd, ICCR, ICCR_ICE, 0);
490+
/* Enable channel and configure rx ack */
491+
iic_set_clr(pd, ICCR, ICCR_ICE, 0);
484492

485-
/* Set the clock */
486-
iic_wr(pd, ICCL, pd->iccl & 0xff);
487-
iic_wr(pd, ICCH, pd->icch & 0xff);
493+
/* Set the clock */
494+
iic_wr(pd, ICCL, pd->iccl & 0xff);
495+
iic_wr(pd, ICCH, pd->icch & 0xff);
496+
}
488497

489498
pd->msg = usr_msg;
490499
pd->pos = -1;
@@ -495,6 +504,30 @@ static int start_ch(struct sh_mobile_i2c_data *pd, struct i2c_msg *usr_msg)
495504
return 0;
496505
}
497506

507+
static int poll_dte(struct sh_mobile_i2c_data *pd)
508+
{
509+
int i;
510+
511+
for (i = 1000; i; i--) {
512+
u_int8_t val = iic_rd(pd, ICSR);
513+
514+
if (val & ICSR_DTE)
515+
break;
516+
517+
if (val & ICSR_TACK)
518+
return -EIO;
519+
520+
udelay(10);
521+
}
522+
523+
if (!i) {
524+
dev_warn(pd->dev, "Timeout polling for DTE!\n");
525+
return -ETIMEDOUT;
526+
}
527+
528+
return 0;
529+
}
530+
498531
static int poll_busy(struct sh_mobile_i2c_data *pd)
499532
{
500533
int i;
@@ -539,13 +572,16 @@ static int sh_mobile_i2c_xfer(struct i2c_adapter *adapter,
539572

540573
/* Process all messages */
541574
for (i = 0; i < num; i++) {
575+
bool do_start = pd->send_stop || !i;
542576
msg = &msgs[i];
577+
pd->send_stop = i == num - 1 || msg->flags & I2C_M_STOP;
543578

544-
err = start_ch(pd, msg);
579+
err = start_ch(pd, msg, do_start);
545580
if (err)
546581
break;
547582

548-
i2c_op(pd, OP_START, 0);
583+
if (do_start)
584+
i2c_op(pd, OP_START, 0);
549585

550586
/* The interrupt handler takes care of the rest... */
551587
k = wait_event_timeout(pd->wait,
@@ -557,7 +593,10 @@ static int sh_mobile_i2c_xfer(struct i2c_adapter *adapter,
557593
break;
558594
}
559595

560-
err = poll_busy(pd);
596+
if (pd->send_stop)
597+
err = poll_busy(pd);
598+
else
599+
err = poll_dte(pd);
561600
if (err < 0)
562601
break;
563602
}
@@ -571,7 +610,7 @@ static int sh_mobile_i2c_xfer(struct i2c_adapter *adapter,
571610

572611
static u32 sh_mobile_i2c_func(struct i2c_adapter *adapter)
573612
{
574-
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
613+
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
575614
}
576615

577616
static struct i2c_algorithm sh_mobile_i2c_algorithm = {

0 commit comments

Comments
 (0)