[PATCH 2/3] i2c/algo-pca: use timeout for checking the state machine

[Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>]

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-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
---
 drivers/i2c/algos/i2c-algo-pca.c      |   39 +++++++++++++++++---------------
 drivers/i2c/busses/i2c-pca-isa.c      |   18 +++++++++++----
 drivers/i2c/busses/i2c-pca-platform.c |   20 ++++++++--------
 3 files changed, 44 insertions(+), 33 deletions(-)

diff --git a/drivers/i2c/algos/i2c-algo-pca.c b/drivers/i2c/algos/i2c-algo-pca.c
index 59ee88a..4153aff 100644
--- a/drivers/i2c/algos/i2c-algo-pca.c
+++ b/drivers/i2c/algos/i2c-algo-pca.c
@@ -60,14 +60,14 @@ 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);
 }
 
 /*
@@ -75,14 +75,14 @@ static void pca_start(struct i2c_algo_pca_data *adap)
  *
  * 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);
 }
 
 /*
@@ -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);
@@ -125,7 +125,7 @@ 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);
 }
 
 /*
@@ -133,7 +133,7 @@ static void pca_address(struct i2c_algo_pca_data *adap,
  *
  * 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);
@@ -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);
 }
 
 /*
@@ -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);
@@ -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,
@@ -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) {
@@ -231,18 +232,18 @@ 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;
 			}
@@ -250,7 +251,7 @@ 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);
 			break;
 
 		case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
@@ -259,21 +260,21 @@ 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 */
@@ -296,7 +297,7 @@ 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",
@@ -322,6 +323,8 @@ static int pca_xfer(struct i2c_adapter *i2c_adap,
 			break;
 		}
 
+		if (!completed)
+			goto out;
 	}
 
 	ret = curmsg;
diff --git a/drivers/i2c/busses/i2c-pca-isa.c b/drivers/i2c/busses/i2c-pca-isa.c
index 84d035c..a523be8 100644
--- a/drivers/i2c/busses/i2c-pca-isa.c
+++ b/drivers/i2c/busses/i2c-pca-isa.c
@@ -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>
@@ -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)
@@ -68,16 +70,22 @@ 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)
diff --git a/drivers/i2c/busses/i2c-pca-platform.c b/drivers/i2c/busses/i2c-pca-platform.c
index 51d179b..df5e593 100644
--- a/drivers/i2c/busses/i2c-pca-platform.c
+++ b/drivers/i2c/busses/i2c-pca-platform.c
@@ -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>
@@ -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)
-- 
1.5.6.5