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i2c: sh_mobile: don't send a stop condition by default inside transfers
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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 <g.liakhovetski@gmx.de>
Signed-off-by: Wolfram Sang <wolfram@the-dreams.de>
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Guennadi Liakhovetski authored and Wolfram Sang committed Feb 10, 2013
1 parent 4b38231 commit e789029
Showing 1 changed file with 59 additions and 20 deletions.
79 changes: 59 additions & 20 deletions drivers/i2c/busses/i2c-sh_mobile.c
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Original file line number Diff line number Diff line change
Expand Up @@ -38,21 +38,21 @@
/* Transmit operation: */
/* */
/* 0 byte transmit */
/* BUS: S A8 ACK P */
/* BUS: S A8 ACK P(*) */
/* IRQ: DTE WAIT */
/* ICIC: */
/* ICCR: 0x94 0x90 */
/* ICDR: A8 */
/* */
/* 1 byte transmit */
/* BUS: S A8 ACK D8(1) ACK P */
/* BUS: S A8 ACK D8(1) ACK P(*) */
/* IRQ: DTE WAIT WAIT */
/* ICIC: -DTE */
/* ICCR: 0x94 0x90 */
/* ICDR: A8 D8(1) */
/* */
/* 2 byte transmit */
/* BUS: S A8 ACK D8(1) ACK D8(2) ACK P */
/* BUS: S A8 ACK D8(1) ACK D8(2) ACK P(*) */
/* IRQ: DTE WAIT WAIT WAIT */
/* ICIC: -DTE */
/* ICCR: 0x94 0x90 */
Expand All @@ -66,20 +66,20 @@
/* 0 byte receive - not supported since slave may hold SDA low */
/* */
/* 1 byte receive [TX] | [RX] */
/* BUS: S A8 ACK | D8(1) ACK P */
/* BUS: S A8 ACK | D8(1) ACK P(*) */
/* IRQ: DTE WAIT | WAIT DTE */
/* ICIC: -DTE | +DTE */
/* ICCR: 0x94 0x81 | 0xc0 */
/* ICDR: A8 | D8(1) */
/* */
/* 2 byte receive [TX]| [RX] */
/* BUS: S A8 ACK | D8(1) ACK D8(2) ACK P */
/* BUS: S A8 ACK | D8(1) ACK D8(2) ACK P(*) */
/* IRQ: DTE WAIT | WAIT WAIT DTE */
/* ICIC: -DTE | +DTE */
/* ICCR: 0x94 0x81 | 0xc0 */
/* ICDR: A8 | D8(1) D8(2) */
/* */
/* 3 byte receive [TX] | [RX] */
/* 3 byte receive [TX] | [RX] (*) */
/* BUS: S A8 ACK | D8(1) ACK D8(2) ACK D8(3) ACK P */
/* IRQ: DTE WAIT | WAIT WAIT WAIT DTE */
/* ICIC: -DTE | +DTE */
Expand All @@ -94,7 +94,7 @@
/* SDA ___\___XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXAAAAAAAAA___/ */
/* SCL \_/1\_/2\_/3\_/4\_/5\_/6\_/7\_/8\___/9\_____/ */
/* */
/* S D7 D6 D5 D4 D3 D2 D1 D0 P */
/* S D7 D6 D5 D4 D3 D2 D1 D0 P(*) */
/* ___ */
/* WAIT IRQ ________________________________/ \___________ */
/* TACK IRQ ____________________________________/ \_______ */
Expand All @@ -103,6 +103,11 @@
/* _______________________________________________ */
/* BUSY __/ \_ */
/* */
/* (*) The STOP condition is only sent by the master at the end of the last */
/* I2C message or if the I2C_M_STOP flag is set. Similarly, the BUSY bit is */
/* only cleared after the STOP condition, so, between messages we have to */
/* poll for the DTE bit. */
/* */

enum sh_mobile_i2c_op {
OP_START = 0,
Expand Down Expand Up @@ -132,6 +137,7 @@ struct sh_mobile_i2c_data {
struct i2c_msg *msg;
int pos;
int sr;
bool send_stop;
};

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

static int start_ch(struct sh_mobile_i2c_data *pd, struct i2c_msg *usr_msg)
static int start_ch(struct sh_mobile_i2c_data *pd, struct i2c_msg *usr_msg,
bool do_init)
{
if (usr_msg->len == 0 && (usr_msg->flags & I2C_M_RD)) {
dev_err(pd->dev, "Unsupported zero length i2c read\n");
return -EIO;
}

/* Initialize channel registers */
iic_set_clr(pd, ICCR, 0, ICCR_ICE);
if (do_init) {
/* Initialize channel registers */
iic_set_clr(pd, ICCR, 0, ICCR_ICE);

/* Enable channel and configure rx ack */
iic_set_clr(pd, ICCR, ICCR_ICE, 0);
/* Enable channel and configure rx ack */
iic_set_clr(pd, ICCR, ICCR_ICE, 0);

/* Set the clock */
iic_wr(pd, ICCL, pd->iccl & 0xff);
iic_wr(pd, ICCH, pd->icch & 0xff);
/* Set the clock */
iic_wr(pd, ICCL, pd->iccl & 0xff);
iic_wr(pd, ICCH, pd->icch & 0xff);
}

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

static int poll_dte(struct sh_mobile_i2c_data *pd)
{
int i;

for (i = 1000; i; i--) {
u_int8_t val = iic_rd(pd, ICSR);

if (val & ICSR_DTE)
break;

if (val & ICSR_TACK)
return -EIO;

udelay(10);
}

if (!i) {
dev_warn(pd->dev, "Timeout polling for DTE!\n");
return -ETIMEDOUT;
}

return 0;
}

static int poll_busy(struct sh_mobile_i2c_data *pd)
{
int i;
Expand Down Expand Up @@ -539,13 +572,16 @@ static int sh_mobile_i2c_xfer(struct i2c_adapter *adapter,

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

err = start_ch(pd, msg);
err = start_ch(pd, msg, do_start);
if (err)
break;

i2c_op(pd, OP_START, 0);
if (do_start)
i2c_op(pd, OP_START, 0);

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

err = poll_busy(pd);
if (pd->send_stop)
err = poll_busy(pd);
else
err = poll_dte(pd);
if (err < 0)
break;
}
Expand All @@ -571,7 +610,7 @@ static int sh_mobile_i2c_xfer(struct i2c_adapter *adapter,

static u32 sh_mobile_i2c_func(struct i2c_adapter *adapter)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
}

static struct i2c_algorithm sh_mobile_i2c_algorithm = {
Expand Down

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