[PATCH v3 REPOST 0/4] i2c : i2c-ibm-iic : use interrupts to perform the data transfer

[PATCH v3 REPOST 0/4] i2c : i2c-ibm-iic : use interrupts to perform the data transfer

[jean-jacques hiblot]

Hello Wolfram,

I'm reposting this patch set with the linux-ppc list in cc as the ibm I2c
controller is primarily (only?) available on ppc platforms.


This patch set aims to improve the performance of the driver for the IBM iic
controller by implementing the data transfer in the interrupt handler.
Using interrupts to trigger the data transfer reduces and make more
deterministic the latencies between indivdual bytes, and consequently reduces
the total transfer time,

In our test environement with multiple masters, this significantly reduces the
rate of i2c errors.

Changes since v2:
 - cosmectics change (comments style, removed a hard-coded value)
 - moved some parts from one patch to another 
 
Changes since v1:
 - split the patch in 4 individual patches. The code has been refactored a bit
   to make the diff easier to read.
 - changed some dev_dbg in dev_err or dev_warn when more appropriate
 
jean-jacques hiblot (4):
  i2c: i2c-ibm-iic: cleanup.
  i2c: i2c-ibm-iic: perform the transfer in the interrupt handler
  i2c: i2c-ibm-iic: Implements transfer abortion
  i2c: i2c-ibm-iic: Implements a polling mode

 drivers/i2c/busses/i2c-ibm_iic.c | 490 +++++++++++++++++++++++----------------
 drivers/i2c/busses/i2c-ibm_iic.h |  20 +-
 2 files changed, 309 insertions(+), 201 deletions(-)

-- 
1.8.4.2

[PATCH v3 REPOST 1/4] i2c: i2c-ibm-iic: cleanup.

[jean-jacques hiblot]

From: jean-jacques hiblot <jjhiblot@gmail.com>

* removed unneeded 'volatile' qualifiers and casts
* use the dev_dbg, dev_err etc. instead of printk
* removed unneeded members for the driver's private data
* fixed the style of the multi-line comments

Signed-off-by: jean-jacques hiblot <jjhiblot@traphandler.com>
Reviewed-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
---
 drivers/i2c/busses/i2c-ibm_iic.c | 135 +++++++++++++++++++++------------------
 drivers/i2c/busses/i2c-ibm_iic.h |   9 +--
 2 files changed, 78 insertions(+), 66 deletions(-)

diff --git a/drivers/i2c/busses/i2c-ibm_iic.c b/drivers/i2c/busses/i2c-ibm_iic.c
index ff3caa0..03ab756 100644
--- a/drivers/i2c/busses/i2c-ibm_iic.c
+++ b/drivers/i2c/busses/i2c-ibm_iic.c
@@ -68,22 +68,26 @@ MODULE_PARM_DESC(iic_force_fast, "Force fast mode (400 kHz)");
 #undef DBG2
 #endif
 
+#  define ERR(dev, f, x...)	dev_err(dev->adap.dev.parent, f, ##x)
+
 #if DBG_LEVEL > 0
-#  define DBG(f,x...)	printk(KERN_DEBUG "ibm-iic" f, ##x)
+#  define DBG(dev, f, x...)	dev_dbg(dev->adap.dev.parent, f, ##x)
 #else
-#  define DBG(f,x...)	((void)0)
+#  define DBG(dev, f, x...)	((void)0)
 #endif
 #if DBG_LEVEL > 1
-#  define DBG2(f,x...) 	DBG(f, ##x)
+#  define DBG2(dev, f, x...)	DBG(dev, f, ##x)
 #else
-#  define DBG2(f,x...) 	((void)0)
+#  define DBG2(dev, f, x...)	((void)0)
 #endif
 #if DBG_LEVEL > 2
 static void dump_iic_regs(const char* header, struct ibm_iic_private* dev)
 {
-	volatile struct iic_regs __iomem *iic = dev->vaddr;
-	printk(KERN_DEBUG "ibm-iic%d: %s\n", dev->idx, header);
-	printk(KERN_DEBUG
+	struct iic_regs __iomem *iic = dev->vaddr;
+	struct device *device = dev.adap.dev.parent;
+
+	dev_dbg(device, ": %s\n", header);
+	dev_dbg(device,
 	       "  cntl     = 0x%02x, mdcntl = 0x%02x\n"
 	       "  sts      = 0x%02x, extsts = 0x%02x\n"
 	       "  clkdiv   = 0x%02x, xfrcnt = 0x%02x\n"
@@ -133,9 +137,9 @@ static inline void iic_interrupt_mode(struct ibm_iic_private* dev, int enable)
  */
 static void iic_dev_init(struct ibm_iic_private* dev)
 {
-	volatile struct iic_regs __iomem *iic = dev->vaddr;
+	struct iic_regs __iomem *iic = dev->vaddr;
 
-	DBG("%d: init\n", dev->idx);
+	DBG(dev, "init\n");
 
 	/* Clear master address */
 	out_8(&iic->lmadr, 0);
@@ -178,11 +182,11 @@ static void iic_dev_init(struct ibm_iic_private* dev)
  */
 static void iic_dev_reset(struct ibm_iic_private* dev)
 {
-	volatile struct iic_regs __iomem *iic = dev->vaddr;
+	struct iic_regs __iomem *iic = dev->vaddr;
 	int i;
 	u8 dc;
 
-	DBG("%d: soft reset\n", dev->idx);
+	DBG(dev, "soft reset\n");
 	DUMP_REGS("reset", dev);
 
     	/* Place chip in the reset state */
@@ -191,7 +195,7 @@ static void iic_dev_reset(struct ibm_iic_private* dev)
 	/* Check if bus is free */
 	dc = in_8(&iic->directcntl);
 	if (!DIRCTNL_FREE(dc)){
-		DBG("%d: trying to regain bus control\n", dev->idx);
+		DBG(dev, "trying to regain bus control\n");
 
 		/* Try to set bus free state */
 		out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC);
@@ -226,7 +230,7 @@ static void iic_dev_reset(struct ibm_iic_private* dev)
  */
 
 /* Wait for SCL and/or SDA to be high */
-static int iic_dc_wait(volatile struct iic_regs __iomem *iic, u8 mask)
+static int iic_dc_wait(struct iic_regs __iomem *iic, u8 mask)
 {
 	unsigned long x = jiffies + HZ / 28 + 2;
 	while ((in_8(&iic->directcntl) & mask) != mask){
@@ -239,19 +243,18 @@ static int iic_dc_wait(volatile struct iic_regs __iomem *iic, u8 mask)
 
 static int iic_smbus_quick(struct ibm_iic_private* dev, const struct i2c_msg* p)
 {
-	volatile struct iic_regs __iomem *iic = dev->vaddr;
+	struct iic_regs __iomem *iic = dev->vaddr;
 	const struct i2c_timings* t = &timings[dev->fast_mode ? 1 : 0];
 	u8 mask, v, sda;
 	int i, res;
 
 	/* Only 7-bit addresses are supported */
 	if (unlikely(p->flags & I2C_M_TEN)){
-		DBG("%d: smbus_quick - 10 bit addresses are not supported\n",
-			dev->idx);
+		DBG(dev, "smbus_quick - 10 bit addresses are not supported\n");
 		return -EINVAL;
 	}
 
-	DBG("%d: smbus_quick(0x%02x)\n", dev->idx, p->addr);
+	DBG(dev, "smbus_quick(0x%02x)\n", p->addr);
 
 	/* Reset IIC interface */
 	out_8(&iic->xtcntlss, XTCNTLSS_SRST);
@@ -304,7 +307,7 @@ static int iic_smbus_quick(struct ibm_iic_private* dev, const struct i2c_msg* p)
 
 	ndelay(t->buf);
 
-	DBG("%d: smbus_quick -> %s\n", dev->idx, res ? "NACK" : "ACK");
+	DBG(dev, "smbus_quick -> %s\n", res ? "NACK" : "ACK");
 out:
 	/* Remove reset */
 	out_8(&iic->xtcntlss, 0);
@@ -314,7 +317,7 @@ out:
 
 	return res;
 err:
-	DBG("%d: smbus_quick - bus is stuck\n", dev->idx);
+	DBG(dev, "smbus_quick - bus is stuck\n");
 	res = -EREMOTEIO;
 	goto out;
 }
@@ -325,10 +328,10 @@ err:
 static irqreturn_t iic_handler(int irq, void *dev_id)
 {
 	struct ibm_iic_private* dev = (struct ibm_iic_private*)dev_id;
-	volatile struct iic_regs __iomem *iic = dev->vaddr;
+	struct iic_regs __iomem *iic = dev->vaddr;
 
-	DBG2("%d: irq handler, STS = 0x%02x, EXTSTS = 0x%02x\n",
-	     dev->idx, in_8(&iic->sts), in_8(&iic->extsts));
+	DBG2(dev, "irq handler, STS = 0x%02x, EXTSTS = 0x%02x\n",
+	     in_8(&iic->sts), in_8(&iic->extsts));
 
 	/* Acknowledge IRQ and wakeup iic_wait_for_tc */
 	out_8(&iic->sts, STS_IRQA | STS_SCMP);
@@ -343,10 +346,10 @@ static irqreturn_t iic_handler(int irq, void *dev_id)
  */
 static int iic_xfer_result(struct ibm_iic_private* dev)
 {
-	volatile struct iic_regs __iomem *iic = dev->vaddr;
+	struct iic_regs __iomem *iic = dev->vaddr;
 
 	if (unlikely(in_8(&iic->sts) & STS_ERR)){
-		DBG("%d: xfer error, EXTSTS = 0x%02x\n", dev->idx,
+		DBG(dev, "xfer error, EXTSTS = 0x%02x\n",
 			in_8(&iic->extsts));
 
 		/* Clear errors and possible pending IRQs */
@@ -356,13 +359,14 @@ static int iic_xfer_result(struct ibm_iic_private* dev)
 		/* Flush master data buffer */
 		out_8(&iic->mdcntl, in_8(&iic->mdcntl) | MDCNTL_FMDB);
 
-		/* Is bus free?
+		/*
+		 * Is bus free?
 		 * If error happened during combined xfer
 		 * IIC interface is usually stuck in some strange
 		 * state, the only way out - soft reset.
 		 */
 		if ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){
-			DBG("%d: bus is stuck, resetting\n", dev->idx);
+			DBG(dev, "bus is stuck, resetting\n");
 			iic_dev_reset(dev);
 		}
 		return -EREMOTEIO;
@@ -376,10 +380,10 @@ static int iic_xfer_result(struct ibm_iic_private* dev)
  */
 static void iic_abort_xfer(struct ibm_iic_private* dev)
 {
-	volatile struct iic_regs __iomem *iic = dev->vaddr;
+	struct iic_regs __iomem *iic = dev->vaddr;
 	unsigned long x;
 
-	DBG("%d: iic_abort_xfer\n", dev->idx);
+	DBG(dev, "iic_abort_xfer\n");
 
 	out_8(&iic->cntl, CNTL_HMT);
 
@@ -390,7 +394,7 @@ static void iic_abort_xfer(struct ibm_iic_private* dev)
 	x = jiffies + 2;
 	while ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){
 		if (time_after(jiffies, x)){
-			DBG("%d: abort timeout, resetting...\n", dev->idx);
+			DBG(dev, "abort timeout, resetting...\n");
 			iic_dev_reset(dev);
 			return;
 		}
@@ -408,7 +412,7 @@ static void iic_abort_xfer(struct ibm_iic_private* dev)
  */
 static int iic_wait_for_tc(struct ibm_iic_private* dev){
 
-	volatile struct iic_regs __iomem *iic = dev->vaddr;
+	struct iic_regs __iomem *iic = dev->vaddr;
 	int ret = 0;
 
 	if (dev->irq >= 0){
@@ -417,9 +421,9 @@ static int iic_wait_for_tc(struct ibm_iic_private* dev){
 			!(in_8(&iic->sts) & STS_PT), dev->adap.timeout);
 
 		if (unlikely(ret < 0))
-			DBG("%d: wait interrupted\n", dev->idx);
+			DBG(dev, "wait interrupted\n");
 		else if (unlikely(in_8(&iic->sts) & STS_PT)){
-			DBG("%d: wait timeout\n", dev->idx);
+			DBG(dev, "wait timeout\n");
 			ret = -ETIMEDOUT;
 		}
 	}
@@ -429,13 +433,13 @@ static int iic_wait_for_tc(struct ibm_iic_private* dev){
 
 		while (in_8(&iic->sts) & STS_PT){
 			if (unlikely(time_after(jiffies, x))){
-				DBG("%d: poll timeout\n", dev->idx);
+				DBG(dev, "poll timeout\n");
 				ret = -ETIMEDOUT;
 				break;
 			}
 
 			if (unlikely(signal_pending(current))){
-				DBG("%d: poll interrupted\n", dev->idx);
+				DBG(dev, "poll interrupted\n");
 				ret = -ERESTARTSYS;
 				break;
 			}
@@ -448,7 +452,7 @@ static int iic_wait_for_tc(struct ibm_iic_private* dev){
 	else
 		ret = iic_xfer_result(dev);
 
-	DBG2("%d: iic_wait_for_tc -> %d\n", dev->idx, ret);
+	DBG2(dev, "iic_wait_for_tc -> %d\n", ret);
 
 	return ret;
 }
@@ -459,7 +463,7 @@ static int iic_wait_for_tc(struct ibm_iic_private* dev){
 static int iic_xfer_bytes(struct ibm_iic_private* dev, struct i2c_msg* pm,
 			  int combined_xfer)
 {
-	volatile struct iic_regs __iomem *iic = dev->vaddr;
+	struct iic_regs __iomem *iic = dev->vaddr;
 	char* buf = pm->buf;
 	int i, j, loops, ret = 0;
 	int len = pm->len;
@@ -475,14 +479,14 @@ static int iic_xfer_bytes(struct ibm_iic_private* dev, struct i2c_msg* pm,
 
 		if (!(cntl & CNTL_RW))
 			for (j = 0; j < count; ++j)
-				out_8((void __iomem *)&iic->mdbuf, *buf++);
+				out_8(&iic->mdbuf, *buf++);
 
 		if (i < loops - 1)
 			cmd |= CNTL_CHT;
 		else if (combined_xfer)
 			cmd |= CNTL_RPST;
 
-		DBG2("%d: xfer_bytes, %d, CNTL = 0x%02x\n", dev->idx, count, cmd);
+		DBG2(dev, "xfer_bytes, %d, CNTL = 0x%02x\n", count, cmd);
 
 		/* Start transfer */
 		out_8(&iic->cntl, cmd);
@@ -493,8 +497,8 @@ static int iic_xfer_bytes(struct ibm_iic_private* dev, struct i2c_msg* pm,
 		if (unlikely(ret < 0))
 			break;
 		else if (unlikely(ret != count)){
-			DBG("%d: xfer_bytes, requested %d, transferred %d\n",
-				dev->idx, count, ret);
+			DBG(dev, "xfer_bytes, requested %d, transferred %d\n",
+				count, ret);
 
 			/* If it's not a last part of xfer, abort it */
 			if (combined_xfer || (i < loops - 1))
@@ -506,7 +510,7 @@ static int iic_xfer_bytes(struct ibm_iic_private* dev, struct i2c_msg* pm,
 
 		if (cntl & CNTL_RW)
 			for (j = 0; j < count; ++j)
-				*buf++ = in_8((void __iomem *)&iic->mdbuf);
+				*buf++ = in_8(&iic->mdbuf);
 	}
 
 	return ret > 0 ? 0 : ret;
@@ -517,10 +521,10 @@ static int iic_xfer_bytes(struct ibm_iic_private* dev, struct i2c_msg* pm,
  */
 static inline void iic_address(struct ibm_iic_private* dev, struct i2c_msg* msg)
 {
-	volatile struct iic_regs __iomem *iic = dev->vaddr;
+	struct iic_regs __iomem *iic = dev->vaddr;
 	u16 addr = msg->addr;
 
-	DBG2("%d: iic_address, 0x%03x (%d-bit)\n", dev->idx,
+	DBG2(dev, "iic_address, 0x%03x (%d-bit)\n",
 		addr, msg->flags & I2C_M_TEN ? 10 : 7);
 
 	if (msg->flags & I2C_M_TEN){
@@ -553,46 +557,49 @@ static inline int iic_address_neq(const struct i2c_msg* p1,
 static int iic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 {
     	struct ibm_iic_private* dev = (struct ibm_iic_private*)(i2c_get_adapdata(adap));
-	volatile struct iic_regs __iomem *iic = dev->vaddr;
+	struct iic_regs __iomem *iic = dev->vaddr;
 	int i, ret = 0;
 
-	DBG2("%d: iic_xfer, %d msg(s)\n", dev->idx, num);
+	DBG2(dev, "iic_xfer, %d msg(s)\n", num);
 
 	if (!num)
 		return 0;
 
-	/* Check the sanity of the passed messages.
+	/*
+	 * Check the sanity of the passed messages.
 	 * Uhh, generic i2c layer is more suitable place for such code...
 	 */
 	if (unlikely(iic_invalid_address(&msgs[0]))){
-		DBG("%d: invalid address 0x%03x (%d-bit)\n", dev->idx,
+		DBG(dev, "invalid address 0x%03x (%d-bit)\n",
 			msgs[0].addr, msgs[0].flags & I2C_M_TEN ? 10 : 7);
 		return -EINVAL;
 	}
 	for (i = 0; i < num; ++i){
 		if (unlikely(msgs[i].len <= 0)){
 			if (num == 1 && !msgs[0].len){
-				/* Special case for I2C_SMBUS_QUICK emulation.
+				/*
+				 * Special case for I2C_SMBUS_QUICK emulation.
 				 * IBM IIC doesn't support 0-length transactions
 				 * so we have to emulate them using bit-banging.
 				 */
 				return iic_smbus_quick(dev, &msgs[0]);
 			}
-			DBG("%d: invalid len %d in msg[%d]\n", dev->idx,
+			DBG(dev, "invalid len %d in msg[%d]\n",
 				msgs[i].len, i);
 			return -EINVAL;
 		}
 		if (unlikely(iic_address_neq(&msgs[0], &msgs[i]))){
-			DBG("%d: invalid addr in msg[%d]\n", dev->idx, i);
+			DBG(dev, "invalid addr in msg[%d]\n", i);
 			return -EINVAL;
 		}
 	}
 
 	/* Check bus state */
 	if (unlikely((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE)){
-		DBG("%d: iic_xfer, bus is not free\n", dev->idx);
+		DBG(dev, "iic_xfer, bus is not free\n");
 
-		/* Usually it means something serious has happened.
+		/*
+		 * Usually it means something serious has happened.
 		 * We *cannot* have unfinished previous transfer
 		 * so it doesn't make any sense to try to stop it.
 		 * Probably we were not able to recover from the
@@ -603,7 +610,7 @@ static int iic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 		iic_dev_reset(dev);
 
 		if ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){
-			DBG("%d: iic_xfer, bus is still not free\n", dev->idx);
+			DBG(dev, "iic_xfer, bus is still not free\n");
 			return -EREMOTEIO;
 		}
 	}
@@ -635,15 +642,18 @@ static const struct i2c_algorithm iic_algo = {
 /*
  * Calculates IICx_CLCKDIV value for a specific OPB clock frequency
  */
-static inline u8 iic_clckdiv(unsigned int opb)
+static inline u8 iic_clckdiv(struct ibm_iic_private *dev, unsigned int opb)
 {
-	/* Compatibility kludge, should go away after all cards
+	struct device *device = dev->adap.dev.parent;
+
+	/*
+	 * Compatibility kludge, should go away after all cards
 	 * are fixed to fill correct value for opbfreq.
 	 * Previous driver version used hardcoded divider value 4,
 	 * it corresponds to OPB frequency from the range (40, 50] MHz
 	 */
 	if (!opb){
-		printk(KERN_WARNING "ibm-iic: using compatibility value for OPB freq,"
+		dev_warn(device, "iic_clckdiv: using compatibility value for OPB freq,"
 			" fix your board specific setup\n");
 		opb = 50000000;
 	}
@@ -652,7 +662,7 @@ static inline u8 iic_clckdiv(unsigned int opb)
 	opb /= 1000000;
 
 	if (opb < 20 || opb > 150){
-		printk(KERN_WARNING "ibm-iic: invalid OPB clock frequency %u MHz\n",
+		dev_warn(device, "iic_clckdiv: invalid OPB clock frequency %u MHz\n",
 			opb);
 		opb = opb < 20 ? 20 : 150;
 	}
@@ -670,16 +680,17 @@ static int iic_request_irq(struct platform_device *ofdev,
 
 	irq = irq_of_parse_and_map(np, 0);
 	if (!irq) {
-		dev_err(&ofdev->dev, "irq_of_parse_and_map failed\n");
+		ERR(dev, "irq_of_parse_and_map failed\n");
 		return 0;
 	}
 
-	/* Disable interrupts until we finish initialization, assumes
+	/*
+	 * Disable interrupts until we finish initialization, assumes
 	 *  level-sensitive IRQ setup...
 	 */
 	iic_interrupt_mode(dev, 0);
 	if (request_irq(irq, iic_handler, 0, "IBM IIC", dev)) {
-		dev_err(&ofdev->dev, "request_irq %d failed\n", irq);
+		ERR(dev, "request_irq %d failed\n", irq);
 		/* Fallback to the polling mode */
 		return 0;
 	}
@@ -717,7 +728,7 @@ static int iic_probe(struct platform_device *ofdev)
 
 	dev->irq = iic_request_irq(ofdev, dev);
 	if (!dev->irq)
-		dev_warn(&ofdev->dev, "using polling mode\n");
+		dev_info(&ofdev->dev, "using polling mode\n");
 
 	/* Board specific settings */
 	if (iic_force_fast || of_get_property(np, "fast-mode", NULL))
@@ -733,7 +744,7 @@ static int iic_probe(struct platform_device *ofdev)
 		}
 	}
 
-	dev->clckdiv = iic_clckdiv(*freq);
+	dev->clckdiv = iic_clckdiv(dev, *freq);
 	dev_dbg(&ofdev->dev, "clckdiv = %d\n", dev->clckdiv);
 
 	/* Initialize IIC interface */
diff --git a/drivers/i2c/busses/i2c-ibm_iic.h b/drivers/i2c/busses/i2c-ibm_iic.h
index fdaa482..1efce5d 100644
--- a/drivers/i2c/busses/i2c-ibm_iic.h
+++ b/drivers/i2c/busses/i2c-ibm_iic.h
@@ -25,8 +25,10 @@
 #include <linux/i2c.h>
 
 struct iic_regs {
-	u16 mdbuf;
-	u16 sbbuf;
+	u8 mdbuf;
+	u8 reserved1;
+	u8 sbbuf;
+	u8 reserved2;
 	u8 lmadr;
 	u8 hmadr;
 	u8 cntl;
@@ -44,9 +46,8 @@ struct iic_regs {
 
 struct ibm_iic_private {
 	struct i2c_adapter adap;
-	volatile struct iic_regs __iomem *vaddr;
+	struct iic_regs __iomem *vaddr;
 	wait_queue_head_t wq;
-	int idx;
 	int irq;
 	int fast_mode;
 	u8  clckdiv;
-- 
1.8.4.2

[PATCH v3 REPOST 2/4] i2c: i2c-ibm-iic: perform the transfer in the interrupt handler

[jean-jacques hiblot]

From: jean-jacques hiblot <jjhiblot@gmail.com>

The current implementation uses the interrupt only to wakeup the process doing
the data transfer. While this is working, it introduces indesirable latencies.
This patch implements the data transfer in the interrupt handler. It keeps the
latency between individual bytes low and the jitter on the total transfer time
is reduced.

Note: transfer abortion and polling mode are not working and will be supported
in further patches

This was tested on a custom board built around a PPC460EX with several
different I2C devices (including EEPROMs and smart batteries)

Signed-off-by: jean-jacques hiblot <jjhiblot@traphandler.com>
Reviewed-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
---
 drivers/i2c/busses/i2c-ibm_iic.c | 230 ++++++++++++++++++++++++++++-----------
 drivers/i2c/busses/i2c-ibm_iic.h |   8 ++
 2 files changed, 177 insertions(+), 61 deletions(-)

diff --git a/drivers/i2c/busses/i2c-ibm_iic.c b/drivers/i2c/busses/i2c-ibm_iic.c
index 03ab756..a92e8f6 100644
--- a/drivers/i2c/busses/i2c-ibm_iic.c
+++ b/drivers/i2c/busses/i2c-ibm_iic.c
@@ -58,6 +58,8 @@ static bool iic_force_fast;
 module_param(iic_force_fast, bool, 0);
 MODULE_PARM_DESC(iic_force_fast, "Force fast mode (400 kHz)");
 
+#define FIFO_FLUSH_TIMEOUT 100
+
 #define DBG_LEVEL 0
 
 #ifdef DBG
@@ -125,6 +127,7 @@ static struct i2c_timings {
 	.high 	= 600,
 	.buf	= 1300,
 }};
+static int iic_xfer_bytes(struct ibm_iic_private *dev);
 
 /* Enable/disable interrupt generation */
 static inline void iic_interrupt_mode(struct ibm_iic_private* dev, int enable)
@@ -167,8 +170,8 @@ static void iic_dev_init(struct ibm_iic_private* dev)
 	/* Clear control register */
 	out_8(&iic->cntl, 0);
 
-	/* Enable interrupts if possible */
-	iic_interrupt_mode(dev, dev->irq >= 0);
+	/* Start with each individual interrupt masked*/
+	iic_interrupt_mode(dev, 0);
 
 	/* Set mode control */
 	out_8(&iic->mdcntl, MDCNTL_FMDB | MDCNTL_EINT | MDCNTL_EUBS
@@ -327,16 +330,8 @@ err:
  */
 static irqreturn_t iic_handler(int irq, void *dev_id)
 {
-	struct ibm_iic_private* dev = (struct ibm_iic_private*)dev_id;
-	struct iic_regs __iomem *iic = dev->vaddr;
-
-	DBG2(dev, "irq handler, STS = 0x%02x, EXTSTS = 0x%02x\n",
-	     in_8(&iic->sts), in_8(&iic->extsts));
-
-	/* Acknowledge IRQ and wakeup iic_wait_for_tc */
-	out_8(&iic->sts, STS_IRQA | STS_SCMP);
-	wake_up_interruptible(&dev->wq);
-
+	struct ibm_iic_private *dev = (struct ibm_iic_private *) dev_id;
+	iic_xfer_bytes(dev);
 	return IRQ_HANDLED;
 }
 
@@ -460,60 +455,129 @@ static int iic_wait_for_tc(struct ibm_iic_private* dev){
 /*
  * Low level master transfer routine
  */
-static int iic_xfer_bytes(struct ibm_iic_private* dev, struct i2c_msg* pm,
-			  int combined_xfer)
+static int iic_xfer_bytes(struct ibm_iic_private *dev)
 {
-	struct iic_regs __iomem *iic = dev->vaddr;
-	char* buf = pm->buf;
-	int i, j, loops, ret = 0;
-	int len = pm->len;
-
-	u8 cntl = (in_8(&iic->cntl) & CNTL_AMD) | CNTL_PT;
-	if (pm->flags & I2C_M_RD)
-		cntl |= CNTL_RW;
+	struct i2c_msg *pm = &(dev->msgs[dev->current_msg]);
+	struct iic_regs *iic = dev->vaddr;
+	u8 cntl = in_8(&iic->cntl) & CNTL_AMD;
+	int count;
+	u32 status;
+	u32 ext_status;
+
+	/* First check the status register */
+	status = in_8(&iic->sts);
+	ext_status = in_8(&iic->extsts);
+
+	/* and acknowledge the interrupt */
+	out_8(&iic->extsts, EXTSTS_IRQP | EXTSTS_IRQD | EXTSTS_LA |
+			    EXTSTS_ICT | EXTSTS_XFRA);
+	out_8(&iic->sts, STS_IRQA | STS_SCMP);
 
-	loops = (len + 3) / 4;
-	for (i = 0; i < loops; ++i, len -= 4){
-		int count = len > 4 ? 4 : len;
-		u8 cmd = cntl | ((count - 1) << CNTL_TCT_SHIFT);
+	if ((status & STS_ERR) ||
+	    (ext_status & (EXTSTS_LA | EXTSTS_ICT | EXTSTS_XFRA))) {
+		DBG(dev, "status 0x%x\n", status);
+		DBG(dev, "extended status 0x%x\n", ext_status);
+		if (status & STS_ERR)
+			ERR(dev, "Error detected\n");
+		if (ext_status & EXTSTS_LA)
+			DBG(dev, "Lost arbitration\n");
+		if (ext_status & EXTSTS_ICT)
+			ERR(dev, "Incomplete transfer\n");
+		if (ext_status & EXTSTS_XFRA)
+			ERR(dev, "Transfer aborted\n");
+
+		dev->status = -EIO;
+		dev->transfer_complete = 1;
+		complete(&dev->iic_compl);
+		return dev->status;
+	}
 
-		if (!(cntl & CNTL_RW))
-			for (j = 0; j < count; ++j)
-				out_8(&iic->mdbuf, *buf++);
+	if (dev->msgs == NULL) {
+		DBG(dev, "spurious !!!!!\n");
+		dev->status = -EINVAL;
+		return dev->status;
+	}
 
-		if (i < loops - 1)
-			cmd |= CNTL_CHT;
-		else if (combined_xfer)
-			cmd |= CNTL_RPST;
+	/* check if there's any data to read from the fifo */
+	if (pm->flags & I2C_M_RD) {
+		while (dev->current_byte_rx < dev->current_byte) {
+			u8 *buf = pm->buf + dev->current_byte_rx;
+			*buf = in_8(&iic->mdbuf);
+			dev->current_byte_rx++;
+			DBG2(dev, "read 0x%x\n", *buf);
+		}
+	}
+	/* check if we must go with the next tranfer */
+	if (pm->len  == dev->current_byte) {
+		DBG2(dev, "going to next transfer\n");
+		dev->current_byte = 0;
+		dev->current_byte_rx = 0;
+		dev->current_msg++;
+		if (dev->current_msg == dev->num_msgs) {
+			DBG2(dev, "end of transfer\n");
+			dev->transfer_complete = 1;
+			complete(&dev->iic_compl);
+			return dev->status;
+		}
+		pm++;
+	}
 
-		DBG2(dev, "xfer_bytes, %d, CNTL = 0x%02x\n", count, cmd);
+	/* take care of the direction */
+	if (pm->flags & I2C_M_RD)
+		cntl |= CNTL_RW;
 
-		/* Start transfer */
-		out_8(&iic->cntl, cmd);
+	/*
+	 * how much data are we going to transfer this time ?
+	 * (up to 4 bytes at once)
+	 */
+	count = pm->len  - dev->current_byte;
+	count = (count > 4) ? 4 : count;
+	cntl |= (count - 1) << CNTL_TCT_SHIFT;
+
+	if ((pm->flags & I2C_M_RD) == 0) {
+		/* This is a write. we must fill the fifo with the data */
+		int i;
+		u8 *buf = pm->buf + dev->current_byte;
+
+		for (i = 0; i < count; i++) {
+			out_8(&iic->mdbuf, buf[i]);
+			DBG2(dev, "write : 0x%x\n", buf[i]);
+		}
+	}
 
-		/* Wait for completion */
-		ret = iic_wait_for_tc(dev);
+	/* will the current transfer complete with this chunk of data ? */
+	if (pm->len  > dev->current_byte + 4) {
+		/*
+		 * we're not done with the current transfer.
+		 * Don't send a repeated start
+		 */
+		cntl |= CNTL_CHT;
+	}
+	/*
+	 * This transfer will be complete with this chunk of data
+	 * BUT is this the last transfer of the list ?
+	 */
+	else if (dev->current_msg != (dev->num_msgs-1)) {
+		/* not the last tranfer */
+		cntl |= CNTL_RPST; /* Do not send a STOP condition */
+		/* check if the NEXT transfer needs a repeated start */
+		if (pm[1].flags & I2C_M_NOSTART)
+			cntl |= CNTL_CHT;
+	}
 
-		if (unlikely(ret < 0))
-			break;
-		else if (unlikely(ret != count)){
-			DBG(dev, "xfer_bytes, requested %d, transferred %d\n",
-				count, ret);
+	if ((cntl & CNTL_RPST) == 0)
+		DBG2(dev, "STOP required\n");
 
-			/* If it's not a last part of xfer, abort it */
-			if (combined_xfer || (i < loops - 1))
-    				iic_abort_xfer(dev);
+	if ((cntl & CNTL_CHT) == 0)
+		DBG2(dev, "next transfer will begin with START\n");
 
-			ret = -EREMOTEIO;
-			break;
-		}
+	/* keep track of the amount of data transfered (RX and TX) */
+	dev->current_byte += count;
 
-		if (cntl & CNTL_RW)
-			for (j = 0; j < count; ++j)
-				*buf++ = in_8(&iic->mdbuf);
-	}
+	/* actually start the transfer of the current data chunk */
+	out_8(&iic->cntl, cntl | CNTL_PT);
 
-	return ret > 0 ? 0 : ret;
+	return 0;
 }
 
 /*
@@ -614,19 +678,63 @@ static int iic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 			return -EREMOTEIO;
 		}
 	}
-	else {
-		/* Flush master data buffer (just in case) */
-		out_8(&iic->mdcntl, in_8(&iic->mdcntl) | MDCNTL_FMDB);
+
+	dev->current_byte = dev->current_msg = dev->current_byte_rx = 0;
+	dev->transfer_complete = 0;
+	dev->status = 0;
+	dev->msgs = msgs;
+	dev->num_msgs = num;
+
+	/* clear the buffers */
+	out_8(&iic->mdcntl, MDCNTL_FMDB);
+	i = FIFO_FLUSH_TIMEOUT;
+	while (in_8(&iic->mdcntl) & MDCNTL_FMDB) {
+		if (i-- < 0) {
+			DBG(dev, "iic_xfer, unable to flush\n");
+			return -EREMOTEIO;
+		}
 	}
 
+	/* clear all interrupts masks */
+	out_8(&iic->intmsk, 0x0);
+	/* clear any status */
+	out_8(&iic->sts, STS_IRQA | STS_SCMP);
+	out_8(&iic->extsts, EXTSTS_IRQP | EXTSTS_IRQD | EXTSTS_LA |
+			    EXTSTS_ICT | EXTSTS_XFRA);
+
 	/* Load slave address */
 	iic_address(dev, &msgs[0]);
 
-	/* Do real transfer */
-    	for (i = 0; i < num && !ret; ++i)
-		ret = iic_xfer_bytes(dev, &msgs[i], i < num - 1);
+	init_completion(&dev->iic_compl);
+
+	/* start the transfer */
+	ret = iic_xfer_bytes(dev);
+
+	if (ret == 0) {
+		/* enable the interrupts */
+		out_8(&iic->mdcntl, MDCNTL_EINT);
+		/*  unmask the interrupts */
+		out_8(&iic->intmsk,	INTRMSK_EIMTC | INTRMSK_EITA  |
+					INTRMSK_EIIC | INTRMSK_EIHE);
+		/*  wait for the transfer to complete */
+		ret = wait_for_completion_interruptible_timeout(
+			&dev->iic_compl, num * HZ);
+		/* mask the interrupts */
+		out_8(&iic->intmsk, 0);
+	}
 
-	return ret < 0 ? ret : num;
+	if (ret == 0) {
+		ERR(dev, "transfer timed out\n");
+		ret = -ETIMEDOUT;
+	} else if (ret < 0) {
+		if (ret == -ERESTARTSYS)
+			ERR(dev, "transfer interrupted\n");
+	} else {
+		/* Transfer is complete */
+		ret = (dev->status) ? dev->status : num;
+	}
+
+	return ret;
 }
 
 static u32 iic_func(struct i2c_adapter *adap)
diff --git a/drivers/i2c/busses/i2c-ibm_iic.h b/drivers/i2c/busses/i2c-ibm_iic.h
index 1efce5d..76c476a 100644
--- a/drivers/i2c/busses/i2c-ibm_iic.h
+++ b/drivers/i2c/busses/i2c-ibm_iic.h
@@ -51,6 +51,14 @@ struct ibm_iic_private {
 	int irq;
 	int fast_mode;
 	u8  clckdiv;
+	struct i2c_msg *msgs;
+	int num_msgs;
+	int current_msg;
+	int current_byte;
+	int current_byte_rx;
+	int transfer_complete;
+	int status;
+	struct completion iic_compl;
 };
 
 /* IICx_CNTL register */
-- 
1.8.4.2

[PATCH v3 REPOST 3/4] i2c: i2c-ibm-iic: Implements transfer abortion

[jean-jacques hiblot]

From: jean-jacques hiblot <jjhiblot@gmail.com>

Clean-up properly when a transfer fails for whatever reason.
Cancel the transfer when the process is signaled.

Signed-off-by: jean-jacques hiblot <jjhiblot@traphandler.com>
---
 drivers/i2c/busses/i2c-ibm_iic.c | 146 ++++++++++-----------------------------
 drivers/i2c/busses/i2c-ibm_iic.h |   2 +-
 2 files changed, 36 insertions(+), 112 deletions(-)

diff --git a/drivers/i2c/busses/i2c-ibm_iic.c b/drivers/i2c/busses/i2c-ibm_iic.c
index a92e8f6..857259e 100644
--- a/drivers/i2c/busses/i2c-ibm_iic.c
+++ b/drivers/i2c/busses/i2c-ibm_iic.c
@@ -336,120 +336,25 @@ static irqreturn_t iic_handler(int irq, void *dev_id)
 }
 
 /*
- * Get master transfer result and clear errors if any.
- * Returns the number of actually transferred bytes or error (<0)
- */
-static int iic_xfer_result(struct ibm_iic_private* dev)
-{
-	struct iic_regs __iomem *iic = dev->vaddr;
-
-	if (unlikely(in_8(&iic->sts) & STS_ERR)){
-		DBG(dev, "xfer error, EXTSTS = 0x%02x\n",
-			in_8(&iic->extsts));
-
-		/* Clear errors and possible pending IRQs */
-		out_8(&iic->extsts, EXTSTS_IRQP | EXTSTS_IRQD |
-			EXTSTS_LA | EXTSTS_ICT | EXTSTS_XFRA);
-
-		/* Flush master data buffer */
-		out_8(&iic->mdcntl, in_8(&iic->mdcntl) | MDCNTL_FMDB);
-
-		/*
-		 * Is bus free?
-		 * If error happened during combined xfer
-		 * IIC interface is usually stuck in some strange
-		 * state, the only way out - soft reset.
-		 */
-		if ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){
-			DBG(dev, "bus is stuck, resetting\n");
-			iic_dev_reset(dev);
-		}
-		return -EREMOTEIO;
-	}
-	else
-		return in_8(&iic->xfrcnt) & XFRCNT_MTC_MASK;
-}
-
-/*
  * Try to abort active transfer.
  */
-static void iic_abort_xfer(struct ibm_iic_private* dev)
+static void iic_abort_xfer(struct ibm_iic_private *dev)
 {
-	struct iic_regs __iomem *iic = dev->vaddr;
-	unsigned long x;
-
-	DBG(dev, "iic_abort_xfer\n");
+	struct device *device = dev->adap.dev.parent;
+	unsigned long end;
 
-	out_8(&iic->cntl, CNTL_HMT);
+	DBG(dev, "aborting transfer\n");
+	/* transfer should be aborted within 10ms */
+	end = jiffies + 10;
+	dev->abort = 1;
 
-	/*
-	 * Wait for the abort command to complete.
-	 * It's not worth to be optimized, just poll (timeout >= 1 tick)
-	 */
-	x = jiffies + 2;
-	while ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){
-		if (time_after(jiffies, x)){
-			DBG(dev, "abort timeout, resetting...\n");
-			iic_dev_reset(dev);
-			return;
-		}
+	while (time_after(end, jiffies) && !dev->transfer_complete)
 		schedule();
-	}
 
-	/* Just to clear errors */
-	iic_xfer_result(dev);
-}
-
-/*
- * Wait for master transfer to complete.
- * It puts current process to sleep until we get interrupt or timeout expires.
- * Returns the number of transferred bytes or error (<0)
- */
-static int iic_wait_for_tc(struct ibm_iic_private* dev){
-
-	struct iic_regs __iomem *iic = dev->vaddr;
-	int ret = 0;
-
-	if (dev->irq >= 0){
-		/* Interrupt mode */
-		ret = wait_event_interruptible_timeout(dev->wq,
-			!(in_8(&iic->sts) & STS_PT), dev->adap.timeout);
-
-		if (unlikely(ret < 0))
-			DBG(dev, "wait interrupted\n");
-		else if (unlikely(in_8(&iic->sts) & STS_PT)){
-			DBG(dev, "wait timeout\n");
-			ret = -ETIMEDOUT;
-		}
-	}
-	else {
-		/* Polling mode */
-		unsigned long x = jiffies + dev->adap.timeout;
-
-		while (in_8(&iic->sts) & STS_PT){
-			if (unlikely(time_after(jiffies, x))){
-				DBG(dev, "poll timeout\n");
-				ret = -ETIMEDOUT;
-				break;
-			}
-
-			if (unlikely(signal_pending(current))){
-				DBG(dev, "poll interrupted\n");
-				ret = -ERESTARTSYS;
-				break;
-			}
-			schedule();
-		}
+	if (!dev->transfer_complete) {
+		dev_err(device, "abort operation failed\n");
+		iic_dev_reset(dev);
 	}
-
-	if (unlikely(ret < 0))
-		iic_abort_xfer(dev);
-	else
-		ret = iic_xfer_result(dev);
-
-	DBG2(dev, "iic_wait_for_tc -> %d\n", ret);
-
-	return ret;
 }
 
 /*
@@ -473,6 +378,13 @@ static int iic_xfer_bytes(struct ibm_iic_private *dev)
 			    EXTSTS_ICT | EXTSTS_XFRA);
 	out_8(&iic->sts, STS_IRQA | STS_SCMP);
 
+	if (dev->status == -ECANCELED) {
+		DBG(dev, "abort completed\n");
+		dev->transfer_complete = 1;
+		complete(&dev->iic_compl);
+		return dev->status;
+	}
+
 	if ((status & STS_ERR) ||
 	    (ext_status & (EXTSTS_LA | EXTSTS_ICT | EXTSTS_XFRA))) {
 		DBG(dev, "status 0x%x\n", status);
@@ -577,7 +489,14 @@ static int iic_xfer_bytes(struct ibm_iic_private *dev)
 	/* actually start the transfer of the current data chunk */
 	out_8(&iic->cntl, cntl | CNTL_PT);
 
-	return 0;
+	/* The transfer must be aborted. */
+	if (dev->abort) {
+		DBG(dev, "aborting\n");
+		out_8(&iic->cntl, CNTL_HMT);
+		dev->status = -ECANCELED;
+	}
+
+	return dev->status;
 }
 
 /*
@@ -682,6 +601,7 @@ static int iic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 	dev->current_byte = dev->current_msg = dev->current_byte_rx = 0;
 	dev->transfer_complete = 0;
 	dev->status = 0;
+	dev->abort = 0;
 	dev->msgs = msgs;
 	dev->num_msgs = num;
 
@@ -719,8 +639,10 @@ static int iic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 		/*  wait for the transfer to complete */
 		ret = wait_for_completion_interruptible_timeout(
 			&dev->iic_compl, num * HZ);
-		/* mask the interrupts */
-		out_8(&iic->intmsk, 0);
+		/*
+		 * we don't mask the interrupts here because we may
+		 * need them to abort the transfer gracefully
+		 */
 	}
 
 	if (ret == 0) {
@@ -729,11 +651,15 @@ static int iic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 	} else if (ret < 0) {
 		if (ret == -ERESTARTSYS)
 			ERR(dev, "transfer interrupted\n");
+		iic_abort_xfer(dev);
 	} else {
 		/* Transfer is complete */
 		ret = (dev->status) ? dev->status : num;
 	}
 
+	/* mask the interrupts */
+	out_8(&iic->intmsk, 0);
+
 	return ret;
 }
 
@@ -832,8 +758,6 @@ static int iic_probe(struct platform_device *ofdev)
 		goto error_cleanup;
 	}
 
-	init_waitqueue_head(&dev->wq);
-
 	dev->irq = iic_request_irq(ofdev, dev);
 	if (!dev->irq)
 		dev_info(&ofdev->dev, "using polling mode\n");
diff --git a/drivers/i2c/busses/i2c-ibm_iic.h b/drivers/i2c/busses/i2c-ibm_iic.h
index 76c476a..0ee28a9 100644
--- a/drivers/i2c/busses/i2c-ibm_iic.h
+++ b/drivers/i2c/busses/i2c-ibm_iic.h
@@ -47,7 +47,6 @@ struct iic_regs {
 struct ibm_iic_private {
 	struct i2c_adapter adap;
 	struct iic_regs __iomem *vaddr;
-	wait_queue_head_t wq;
 	int irq;
 	int fast_mode;
 	u8  clckdiv;
@@ -58,6 +57,7 @@ struct ibm_iic_private {
 	int current_byte_rx;
 	int transfer_complete;
 	int status;
+	int abort;
 	struct completion iic_compl;
 };
 
-- 
1.8.4.2

[PATCH v3 REPOST 4/4] i2c: i2c-ibm-iic: Implements a polling mode

[jean-jacques hiblot]

From: jean-jacques hiblot <jjhiblot@gmail.com>

When no valid interrupt is defined for the controller, use polling to handle
the transfers.
The polling mode can also be forced with the "iic_force_poll" module parameter.

Signed-off-by: jean-jacques hiblot <jjhiblot@traphandler.com>
---
 drivers/i2c/busses/i2c-ibm_iic.c | 91 ++++++++++++++++++++++++++++++++--------
 drivers/i2c/busses/i2c-ibm_iic.h |  1 +
 2 files changed, 74 insertions(+), 18 deletions(-)

diff --git a/drivers/i2c/busses/i2c-ibm_iic.c b/drivers/i2c/busses/i2c-ibm_iic.c
index 857259e..aefe228 100644
--- a/drivers/i2c/busses/i2c-ibm_iic.c
+++ b/drivers/i2c/busses/i2c-ibm_iic.c
@@ -336,11 +336,45 @@ static irqreturn_t iic_handler(int irq, void *dev_id)
 }
 
 /*
+ * Polling used when interrupt can't be used
+ */
+static int poll_for_end_of_transfer(struct ibm_iic_private *dev, u32 timeout)
+{
+	struct iic_regs __iomem *iic = dev->vaddr;
+	u32 status;
+	unsigned long end = jiffies + timeout;
+
+	while ((dev->transfer_complete == 0) &&
+	   time_after(end, jiffies) &&
+	   !signal_pending(current)) {
+		status = in_8(&iic->sts);
+		/* check if the transfer is done or an error occured */
+		if ((status & (STS_ERR | STS_SCMP)) || !(status & STS_PT))
+			iic_xfer_bytes(dev);
+		/* The transfer is not complete,
+		 * calling schedule relaxes the CPU load and allows to know
+		 * if the process is being signaled (for abortion)
+		 */
+		if (dev->transfer_complete == 0)
+			schedule();
+	}
+
+	if (signal_pending(current))
+		return -ERESTARTSYS;
+
+	if (dev->transfer_complete == 0)
+		return 0;
+
+	return 1;
+}
+
+/*
  * Try to abort active transfer.
  */
 static void iic_abort_xfer(struct ibm_iic_private *dev)
 {
 	struct device *device = dev->adap.dev.parent;
+	struct iic_regs __iomem *iic = dev->vaddr;
 	unsigned long end;
 
 	DBG(dev, "aborting transfer\n");
@@ -348,8 +382,17 @@ static void iic_abort_xfer(struct ibm_iic_private *dev)
 	end = jiffies + 10;
 	dev->abort = 1;
 
-	while (time_after(end, jiffies) && !dev->transfer_complete)
-		schedule();
+	while (time_after(end, jiffies) && !dev->transfer_complete) {
+		u32 sts;
+		if (dev->use_polling) {
+			sts = in_8(&iic->sts);
+			/* check if the transfer is done or an error occured */
+			if ((sts & (STS_ERR | STS_SCMP)) || !(sts & STS_PT))
+				iic_xfer_bytes(dev);
+		}
+		if (dev->transfer_complete == 0)
+			schedule();
+	}
 
 	if (!dev->transfer_complete) {
 		dev_err(device, "abort operation failed\n");
@@ -381,7 +424,8 @@ static int iic_xfer_bytes(struct ibm_iic_private *dev)
 	if (dev->status == -ECANCELED) {
 		DBG(dev, "abort completed\n");
 		dev->transfer_complete = 1;
-		complete(&dev->iic_compl);
+		if (!dev->use_polling)
+			complete(&dev->iic_compl);
 		return dev->status;
 	}
 
@@ -400,7 +444,8 @@ static int iic_xfer_bytes(struct ibm_iic_private *dev)
 
 		dev->status = -EIO;
 		dev->transfer_complete = 1;
-		complete(&dev->iic_compl);
+		if (!dev->use_polling)
+			complete(&dev->iic_compl);
 		return dev->status;
 	}
 
@@ -428,7 +473,8 @@ static int iic_xfer_bytes(struct ibm_iic_private *dev)
 		if (dev->current_msg == dev->num_msgs) {
 			DBG2(dev, "end of transfer\n");
 			dev->transfer_complete = 1;
-			complete(&dev->iic_compl);
+			if (!dev->use_polling)
+				complete(&dev->iic_compl);
 			return dev->status;
 		}
 		pm++;
@@ -625,24 +671,29 @@ static int iic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 	/* Load slave address */
 	iic_address(dev, &msgs[0]);
 
-	init_completion(&dev->iic_compl);
+	if (!dev->use_polling)
+		init_completion(&dev->iic_compl);
 
 	/* start the transfer */
 	ret = iic_xfer_bytes(dev);
 
 	if (ret == 0) {
-		/* enable the interrupts */
-		out_8(&iic->mdcntl, MDCNTL_EINT);
-		/*  unmask the interrupts */
-		out_8(&iic->intmsk,	INTRMSK_EIMTC | INTRMSK_EITA  |
-					INTRMSK_EIIC | INTRMSK_EIHE);
-		/*  wait for the transfer to complete */
-		ret = wait_for_completion_interruptible_timeout(
-			&dev->iic_compl, num * HZ);
-		/*
-		 * we don't mask the interrupts here because we may
-		 * need them to abort the transfer gracefully
-		 */
+		if (dev->use_polling) {
+			ret = poll_for_end_of_transfer(dev, num * HZ);
+		} else {
+			/* enable the interrupts */
+			out_8(&iic->mdcntl, MDCNTL_EINT);
+			/*  unmask the interrupts */
+			out_8(&iic->intmsk,	INTRMSK_EIMTC | INTRMSK_EITA  |
+						INTRMSK_EIIC | INTRMSK_EIHE);
+			/*  wait for the transfer to complete */
+			ret = wait_for_completion_interruptible_timeout(
+				&dev->iic_compl, num * HZ);
+			/*
+			 * we don't mask the interrupts here because we may
+			 * need them to abort the transfer gracefully
+			 */
+		}
 	}
 
 	if (ret == 0) {
@@ -709,6 +760,8 @@ static int iic_request_irq(struct platform_device *ofdev,
 	struct device_node *np = ofdev->dev.of_node;
 	int irq;
 
+	dev->use_polling = 1;
+
 	if (iic_force_poll)
 		return 0;
 
@@ -729,6 +782,8 @@ static int iic_request_irq(struct platform_device *ofdev,
 		return 0;
 	}
 
+	dev->use_polling = 0;
+
 	return irq;
 }
 
diff --git a/drivers/i2c/busses/i2c-ibm_iic.h b/drivers/i2c/busses/i2c-ibm_iic.h
index 0ee28a9..523cfc1 100644
--- a/drivers/i2c/busses/i2c-ibm_iic.h
+++ b/drivers/i2c/busses/i2c-ibm_iic.h
@@ -58,6 +58,7 @@ struct ibm_iic_private {
 	int transfer_complete;
 	int status;
 	int abort;
+	int use_polling;
 	struct completion iic_compl;
 };
 
-- 
1.8.4.2

Re: [PATCH v3 REPOST 2/4] i2c: i2c-ibm-iic: perform the transfer in the interrupt handler

[Wolfram Sang]

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Hi,

thanks for the submission!

> --- a/drivers/i2c/busses/i2c-ibm_iic.c
> +++ b/drivers/i2c/busses/i2c-ibm_iic.c
> @@ -58,6 +58,8 @@ static bool iic_force_fast;
>  module_param(iic_force_fast, bool, 0);
>  MODULE_PARM_DESC(iic_force_fast, "Force fast mode (400 kHz)");
>  
> +#define FIFO_FLUSH_TIMEOUT 100

100 what? The unit is missing.

> @@ -167,8 +170,8 @@ static void iic_dev_init(struct ibm_iic_private* dev)
>  	/* Clear control register */
>  	out_8(&iic->cntl, 0);
>  
> -	/* Enable interrupts if possible */
> -	iic_interrupt_mode(dev, dev->irq >= 0);
> +	/* Start with each individual interrupt masked*/

Space at the end of comment missing

>  static irqreturn_t iic_handler(int irq, void *dev_id)
>  {
> -	struct ibm_iic_private* dev = (struct ibm_iic_private*)dev_id;
> -	struct iic_regs __iomem *iic = dev->vaddr;
> -
> -	DBG2(dev, "irq handler, STS = 0x%02x, EXTSTS = 0x%02x\n",
> -	     in_8(&iic->sts), in_8(&iic->extsts));
> -
> -	/* Acknowledge IRQ and wakeup iic_wait_for_tc */
> -	out_8(&iic->sts, STS_IRQA | STS_SCMP);
> -	wake_up_interruptible(&dev->wq);
> -
> +	struct ibm_iic_private *dev = (struct ibm_iic_private *) dev_id;
> +	iic_xfer_bytes(dev);

Is iic_xfer_bytes later used when polling, too? Otherwise it could be
simply inserted here.


> +	if ((status & STS_ERR) ||
> +	    (ext_status & (EXTSTS_LA | EXTSTS_ICT | EXTSTS_XFRA))) {
> +		DBG(dev, "status 0x%x\n", status);
> +		DBG(dev, "extended status 0x%x\n", ext_status);
> +		if (status & STS_ERR)
> +			ERR(dev, "Error detected\n");
> +		if (ext_status & EXTSTS_LA)
> +			DBG(dev, "Lost arbitration\n");
> +		if (ext_status & EXTSTS_ICT)
> +			ERR(dev, "Incomplete transfer\n");
> +		if (ext_status & EXTSTS_XFRA)
> +			ERR(dev, "Transfer aborted\n");
> +
> +		dev->status = -EIO;

You could consider returning different fault codes for the different
states. See Documentation/i2c/fault-codes for a guide.

> +	if (dev->msgs == NULL) {
> +		DBG(dev, "spurious !!!!!\n");
> +		dev->status = -EINVAL;
> +		return dev->status;
> +	}

Does that really happen?

And it introduces a build warning:

drivers/i2c/busses/i2c-ibm_iic.c:410:12: warning: 'iic_wait_for_tc' defined but not used [-Wunused-function]


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Re: [PATCH v3 REPOST 3/4] i2c: i2c-ibm-iic: Implements transfer abortion

[Wolfram Sang]

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On Fri, Dec 20, 2013 at 04:12:55PM +0100, jean-jacques hiblot wrote:
> From: jean-jacques hiblot <jjhiblot@gmail.com>
> 
> Clean-up properly when a transfer fails for whatever reason.
> Cancel the transfer when the process is signaled.

Please describe what you do a little. I wonder how you can remove so
much code while keeping the functionality?

> 
> Signed-off-by: jean-jacques hiblot <jjhiblot@traphandler.com>

> -	out_8(&iic->cntl, CNTL_HMT);
> +	DBG(dev, "aborting transfer\n");
> +	/* transfer should be aborted within 10ms */
> +	end = jiffies + 10;

Eeks, msecs_to_jiffies() macro please!

And please consider running checkpatch and sparse over your code. Sparse
gives, for example:

drivers/i2c/busses/i2c-ibm_iic.c:418:24: warning: incorrect type in argument 1 (different address spaces)
drivers/i2c/busses/i2c-ibm_iic.c:418:24:    expected unsigned char const volatile [noderef] [usertype] <asn:2>*addr
drivers/i2c/busses/i2c-ibm_iic.c:418:24:    got unsigned char *<noident>

(This probably due to patch 1 or 2, I'd guess)


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Re: [PATCH v3 REPOST 4/4] i2c: i2c-ibm-iic: Implements a polling mode

[Wolfram Sang]

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On Fri, Dec 20, 2013 at 04:12:56PM +0100, jean-jacques hiblot wrote:
> From: jean-jacques hiblot <jjhiblot@gmail.com>
> 
> When no valid interrupt is defined for the controller, use polling to handle
> the transfers.
> The polling mode can also be forced with the "iic_force_poll" module parameter.
> 
> Signed-off-by: jean-jacques hiblot <jjhiblot@traphandler.com>

Do I understand correctly: Polling was not available after patch 2 until patch 4?

Has the signal handling been tested extensively? Most drivers do not
handle signals because it is usually cumbersome to cancel a transfer
gracefully. That being said, it might work well for you here.


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Re: [PATCH v3 REPOST 2/4] i2c: i2c-ibm-iic: perform the transfer in the interrupt handler

[Jean-Jacques Hiblot]

2014/1/3 Wolfram Sang <wsa@the-dreams.de>:
>
> Hi,
>
> thanks for the submission!
You're welcome :) Thanks for reviewing this.

>
>> --- a/drivers/i2c/busses/i2c-ibm_iic.c
>> +++ b/drivers/i2c/busses/i2c-ibm_iic.c
>> @@ -58,6 +58,8 @@ static bool iic_force_fast;
>>  module_param(iic_force_fast, bool, 0);
>>  MODULE_PARM_DESC(iic_force_fast, "Force fast mode (400 kHz)");
>>
>> +#define FIFO_FLUSH_TIMEOUT 100
>
> 100 what? The unit is missing.

The actual value of this timeout isn't very important. This is used
only to avoid a never ending loop in case the hardware goes into a
really bad state.

>
>> @@ -167,8 +170,8 @@ static void iic_dev_init(struct ibm_iic_private* dev)
>>       /* Clear control register */
>>       out_8(&iic->cntl, 0);
>>
>> -     /* Enable interrupts if possible */
>> -     iic_interrupt_mode(dev, dev->irq >= 0);
>> +     /* Start with each individual interrupt masked*/
>
> Space at the end of comment missing
ok
>
>>  static irqreturn_t iic_handler(int irq, void *dev_id)
>>  {
>> -     struct ibm_iic_private* dev = (struct ibm_iic_private*)dev_id;
>> -     struct iic_regs __iomem *iic = dev->vaddr;
>> -
>> -     DBG2(dev, "irq handler, STS = 0x%02x, EXTSTS = 0x%02x\n",
>> -          in_8(&iic->sts), in_8(&iic->extsts));
>> -
>> -     /* Acknowledge IRQ and wakeup iic_wait_for_tc */
>> -     out_8(&iic->sts, STS_IRQA | STS_SCMP);
>> -     wake_up_interruptible(&dev->wq);
>> -
>> +     struct ibm_iic_private *dev = (struct ibm_iic_private *) dev_id;
>> +     iic_xfer_bytes(dev);
>
> Is iic_xfer_bytes later used when polling, too? Otherwise it could be
> simply inserted here.
Yes it'll be used for polling (implemented in a later patch)
>
>
>> +     if ((status & STS_ERR) ||
>> +         (ext_status & (EXTSTS_LA | EXTSTS_ICT | EXTSTS_XFRA))) {
>> +             DBG(dev, "status 0x%x\n", status);
>> +             DBG(dev, "extended status 0x%x\n", ext_status);
>> +             if (status & STS_ERR)
>> +                     ERR(dev, "Error detected\n");
>> +             if (ext_status & EXTSTS_LA)
>> +                     DBG(dev, "Lost arbitration\n");
>> +             if (ext_status & EXTSTS_ICT)
>> +                     ERR(dev, "Incomplete transfer\n");
>> +             if (ext_status & EXTSTS_XFRA)
>> +                     ERR(dev, "Transfer aborted\n");
>> +
>> +             dev->status = -EIO;
>
> You could consider returning different fault codes for the different
> states. See Documentation/i2c/fault-codes for a guide.
I'll have a look at it.

>
>> +     if (dev->msgs == NULL) {
>> +             DBG(dev, "spurious !!!!!\n");
>> +             dev->status = -EINVAL;
>> +             return dev->status;
>> +     }
>
> Does that really happen?
Not in my test cases (going through i2c dev). But it could if the data
passed to i2c_transfer is malformed.
Should I remove this ?

>
> And it introduces a build warning:
>
> drivers/i2c/busses/i2c-ibm_iic.c:410:12: warning: 'iic_wait_for_tc' defined but not used [-Wunused-function]
>
I posted this some time ago, but I believe I kept this in to help git
produce a diff readable by a human.
It's removed in a later patch

Jean-Jacques

Re: [PATCH v3 REPOST 3/4] i2c: i2c-ibm-iic: Implements transfer abortion

[Jean-Jacques Hiblot]

2014/1/3 Wolfram Sang <wsa@the-dreams.de>:
> On Fri, Dec 20, 2013 at 04:12:55PM +0100, jean-jacques hiblot wrote:
>> From: jean-jacques hiblot <jjhiblot@gmail.com>
>>
>> Clean-up properly when a transfer fails for whatever reason.
>> Cancel the transfer when the process is signaled.
>
> Please describe what you do a little. I wonder how you can remove so
> much code while keeping the functionality?

Well there are 2 reasons why so much code went away.
1) The iic_wait_for_tc() function wasn't used anymore (it should have
disappeared in an earlier patch but the diff was terrible to read)
2) the whole abortion scheme is different. It's now done as a part of
the data transfer. The reason is that the controller doesn't react
properly to abortion when it's not done at the right moment.
The idea here is to abort the transfer right after sending the next
byte to keep the controller happy. If the abortion is asked at the
wrong moment, the controller may not set the abortion complete flag
and the next transfer may fail.


>
>>
>> Signed-off-by: jean-jacques hiblot <jjhiblot@traphandler.com>
>
>> -     out_8(&iic->cntl, CNTL_HMT);
>> +     DBG(dev, "aborting transfer\n");
>> +     /* transfer should be aborted within 10ms */
>> +     end = jiffies + 10;
>
> Eeks, msecs_to_jiffies() macro please!
>
> And please consider running checkpatch and sparse over your code. Sparse
> gives, for example:
>
> drivers/i2c/busses/i2c-ibm_iic.c:418:24: warning: incorrect type in argument 1 (different address spaces)
> drivers/i2c/busses/i2c-ibm_iic.c:418:24:    expected unsigned char const volatile [noderef] [usertype] <asn:2>*addr
> drivers/i2c/busses/i2c-ibm_iic.c:418:24:    got unsigned char *<noident>
>
> (This probably due to patch 1 or 2, I'd guess)
>