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i2c-algo-pca: Use timeout for checking the state machine
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We now timeout also if the state machine does not change within the
given time. For that, the driver-specific completion-functions are
extended to return true or false depending on the timeout. This then
gets checked in the algorithm.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
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Wolfram Sang authored and Jean Delvare committed Mar 28, 2009
1 parent 8e99ada commit 2378bc0
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Showing 3 changed files with 46 additions and 33 deletions.
41 changes: 23 additions & 18 deletions drivers/i2c/algos/i2c-algo-pca.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -60,29 +60,29 @@ static void pca9665_reset(void *pd)
*
* returns after the start condition has occurred
*/
static void pca_start(struct i2c_algo_pca_data *adap)
static int pca_start(struct i2c_algo_pca_data *adap)
{
int sta = pca_get_con(adap);
DEB2("=== START\n");
sta |= I2C_PCA_CON_STA;
sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
pca_set_con(adap, sta);
pca_wait(adap);
return pca_wait(adap);
}

/*
* Generate a repeated start condition on the i2c bus
*
* return after the repeated start condition has occurred
*/
static void pca_repeated_start(struct i2c_algo_pca_data *adap)
static int pca_repeated_start(struct i2c_algo_pca_data *adap)
{
int sta = pca_get_con(adap);
DEB2("=== REPEATED START\n");
sta |= I2C_PCA_CON_STA;
sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
pca_set_con(adap, sta);
pca_wait(adap);
return pca_wait(adap);
}

/*
Expand All @@ -108,7 +108,7 @@ static void pca_stop(struct i2c_algo_pca_data *adap)
*
* returns after the address has been sent
*/
static void pca_address(struct i2c_algo_pca_data *adap,
static int pca_address(struct i2c_algo_pca_data *adap,
struct i2c_msg *msg)
{
int sta = pca_get_con(adap);
Expand All @@ -125,15 +125,15 @@ static void pca_address(struct i2c_algo_pca_data *adap,
sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
pca_set_con(adap, sta);

pca_wait(adap);
return pca_wait(adap);
}

/*
* Transmit a byte.
*
* Returns after the byte has been transmitted
*/
static void pca_tx_byte(struct i2c_algo_pca_data *adap,
static int pca_tx_byte(struct i2c_algo_pca_data *adap,
__u8 b)
{
int sta = pca_get_con(adap);
Expand All @@ -143,7 +143,7 @@ static void pca_tx_byte(struct i2c_algo_pca_data *adap,
sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
pca_set_con(adap, sta);

pca_wait(adap);
return pca_wait(adap);
}

/*
Expand All @@ -163,7 +163,7 @@ static void pca_rx_byte(struct i2c_algo_pca_data *adap,
*
* Returns after next byte has arrived.
*/
static void pca_rx_ack(struct i2c_algo_pca_data *adap,
static int pca_rx_ack(struct i2c_algo_pca_data *adap,
int ack)
{
int sta = pca_get_con(adap);
Expand All @@ -174,7 +174,7 @@ static void pca_rx_ack(struct i2c_algo_pca_data *adap,
sta |= I2C_PCA_CON_AA;

pca_set_con(adap, sta);
pca_wait(adap);
return pca_wait(adap);
}

static int pca_xfer(struct i2c_adapter *i2c_adap,
Expand All @@ -187,6 +187,7 @@ static int pca_xfer(struct i2c_adapter *i2c_adap,
int numbytes = 0;
int state;
int ret;
int completed = 1;
unsigned long timeout = jiffies + i2c_adap->timeout;

while (pca_status(adap) != 0xf8) {
Expand Down Expand Up @@ -232,26 +233,27 @@ static int pca_xfer(struct i2c_adapter *i2c_adap,

switch (state) {
case 0xf8: /* On reset or stop the bus is idle */
pca_start(adap);
completed = pca_start(adap);
break;

case 0x08: /* A START condition has been transmitted */
case 0x10: /* A repeated start condition has been transmitted */
pca_address(adap, msg);
completed = pca_address(adap, msg);
break;

case 0x18: /* SLA+W has been transmitted; ACK has been received */
case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
if (numbytes < msg->len) {
pca_tx_byte(adap, msg->buf[numbytes]);
completed = pca_tx_byte(adap,
msg->buf[numbytes]);
numbytes++;
break;
}
curmsg++; numbytes = 0;
if (curmsg == num)
pca_stop(adap);
else
pca_repeated_start(adap);
completed = pca_repeated_start(adap);
break;

case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
Expand All @@ -260,21 +262,22 @@ static int pca_xfer(struct i2c_adapter *i2c_adap,
goto out;

case 0x40: /* SLA+R has been transmitted; ACK has been received */
pca_rx_ack(adap, msg->len > 1);
completed = pca_rx_ack(adap, msg->len > 1);
break;

case 0x50: /* Data bytes has been received; ACK has been returned */
if (numbytes < msg->len) {
pca_rx_byte(adap, &msg->buf[numbytes], 1);
numbytes++;
pca_rx_ack(adap, numbytes < msg->len - 1);
completed = pca_rx_ack(adap,
numbytes < msg->len - 1);
break;
}
curmsg++; numbytes = 0;
if (curmsg == num)
pca_stop(adap);
else
pca_repeated_start(adap);
completed = pca_repeated_start(adap);
break;

case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
Expand All @@ -297,7 +300,7 @@ static int pca_xfer(struct i2c_adapter *i2c_adap,
if (curmsg == num)
pca_stop(adap);
else
pca_repeated_start(adap);
completed = pca_repeated_start(adap);
} else {
DEB2("NOT ACK sent after data byte received. "
"Not final byte. numbytes %d. len %d\n",
Expand All @@ -323,6 +326,8 @@ static int pca_xfer(struct i2c_adapter *i2c_adap,
break;
}

if (!completed)
goto out;
}

ret = curmsg;
Expand Down
18 changes: 13 additions & 5 deletions drivers/i2c/busses/i2c-pca-isa.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/delay.h>
#include <linux/jiffies.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/wait.h>
Expand All @@ -43,6 +44,7 @@ static int irq = -1;
* in the actual clock rate */
static int clock = 59000;

static struct i2c_adapter pca_isa_ops;
static wait_queue_head_t pca_wait;

static void pca_isa_writebyte(void *pd, int reg, int val)
Expand All @@ -69,16 +71,22 @@ static int pca_isa_readbyte(void *pd, int reg)

static int pca_isa_waitforcompletion(void *pd)
{
int ret = 0;
long ret = ~0;
unsigned long timeout;

if (irq > -1) {
ret = wait_event_interruptible(pca_wait,
pca_isa_readbyte(pd, I2C_PCA_CON) & I2C_PCA_CON_SI);
ret = wait_event_interruptible_timeout(pca_wait,
pca_isa_readbyte(pd, I2C_PCA_CON)
& I2C_PCA_CON_SI, pca_isa_ops.timeout);
} else {
while ((pca_isa_readbyte(pd, I2C_PCA_CON) & I2C_PCA_CON_SI) == 0)
/* Do polling */
timeout = jiffies + pca_isa_ops.timeout;
while (((pca_isa_readbyte(pd, I2C_PCA_CON)
& I2C_PCA_CON_SI) == 0)
&& (ret = time_before(jiffies, timeout)))
udelay(100);
}
return ret;
return ret > 0;
}

static void pca_isa_resetchip(void *pd)
Expand Down
20 changes: 10 additions & 10 deletions drivers/i2c/busses/i2c-pca-platform.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/jiffies.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
Expand Down Expand Up @@ -81,24 +82,23 @@ static void i2c_pca_pf_writebyte32(void *pd, int reg, int val)
static int i2c_pca_pf_waitforcompletion(void *pd)
{
struct i2c_pca_pf_data *i2c = pd;
int ret = 0;
long ret = ~0;
unsigned long timeout;

if (i2c->irq) {
ret = wait_event_interruptible(i2c->wait,
ret = wait_event_interruptible_timeout(i2c->wait,
i2c->algo_data.read_byte(i2c, I2C_PCA_CON)
& I2C_PCA_CON_SI);
& I2C_PCA_CON_SI, i2c->adap.timeout);
} else {
/*
* Do polling...
* XXX: Could get stuck in extreme cases!
* Maybe add timeout, but using irqs is preferred anyhow.
*/
while ((i2c->algo_data.read_byte(i2c, I2C_PCA_CON)
/* Do polling */
timeout = jiffies + i2c->adap.timeout;
while (((i2c->algo_data.read_byte(i2c, I2C_PCA_CON)
& I2C_PCA_CON_SI) == 0)
&& (ret = time_before(jiffies, timeout)))
udelay(100);
}

return ret;
return ret > 0;
}

static void i2c_pca_pf_dummyreset(void *pd)
Expand Down

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