commit 07c5a1b63590e2a7c1e04f13e0577eb455ef9918
author Siva Durga Prasad Paladugu <siva.durga.paladugu@xilinx.com> Thu Mar 07 11:52:49 2019 +0100
committer Heiko Schocher <hs@denx.de> Fri Mar 08 05:52:38 2019 +0100
tree 896447a65da5433b59edbc098e2b6be15086c4a7
parent 4f0205bd6bbe4306b74895c16d5f6e469f0cebad

i2c: i2c_cdns: Add support for handling arbitration lost

This patch adds support for handling arbitration lost
in case of multi master mode. When an arbitration lost
is detected, it retries for 10 times before failing.

Signed-off-by: Siva Durga Prasad Paladugu <siva.durga.paladugu@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Heiko Schocher <hs@denx.de>

drivers/i2c/i2c-cdns.c

diff --git a/drivers/i2c/i2c-cdns.c b/drivers/i2c/i2c-cdns.c
index b391c0b..1af94d1 100644
--- a/drivers/i2c/i2c-cdns.c
+++ b/drivers/i2c/i2c-cdns.c
@@ -80,6 +80,8 @@
 
 #define CDNS_I2C_BROKEN_HOLD_BIT	BIT(0)
 
+#define CDNS_I2C_ARB_LOST_MAX_RETRIES	10
+
 #ifdef DEBUG
 static void cdns_i2c_debug_status(struct cdns_i2c_regs *cdns_i2c)
 {
@@ -234,11 +236,17 @@
 	return 0;
 }
 
+static inline u32 is_arbitration_lost(struct cdns_i2c_regs *regs)
+{
+	return (readl(&regs->interrupt_status) & CDNS_I2C_INTERRUPT_ARBLOST);
+}
+
 static int cdns_i2c_write_data(struct i2c_cdns_bus *i2c_bus, u32 addr, u8 *data,
 			       u32 len)
 {
 	u8 *cur_data = data;
 	struct cdns_i2c_regs *regs = i2c_bus->regs;
+	u32 ret;
 
 	/* Set the controller in Master transmit mode and clear FIFO */
 	setbits_le32(&regs->control, CDNS_I2C_CONTROL_CLR_FIFO);
@@ -255,25 +263,38 @@
 
 	writel(addr, &regs->address);
 
-	while (len--) {
+	while (len-- && !is_arbitration_lost(regs)) {
 		writel(*(cur_data++), &regs->data);
 		if (readl(&regs->transfer_size) == CDNS_I2C_FIFO_DEPTH) {
-			if (!cdns_i2c_wait(regs, CDNS_I2C_INTERRUPT_COMP)) {
-				/* Release the bus */
-				clrbits_le32(&regs->control,
-					     CDNS_I2C_CONTROL_HOLD);
-				return -ETIMEDOUT;
-			}
+			ret = cdns_i2c_wait(regs, CDNS_I2C_INTERRUPT_COMP |
+					    CDNS_I2C_INTERRUPT_ARBLOST);
+			if (ret & CDNS_I2C_INTERRUPT_ARBLOST)
+				return -EAGAIN;
+			if (ret & CDNS_I2C_INTERRUPT_COMP)
+				continue;
+			/* Release the bus */
+			clrbits_le32(&regs->control,
+				     CDNS_I2C_CONTROL_HOLD);
+			return -ETIMEDOUT;
 		}
 	}
 
+	if (len && is_arbitration_lost(regs))
+		return -EAGAIN;
+
 	/* All done... release the bus */
 	if (!i2c_bus->hold_flag)
 		clrbits_le32(&regs->control, CDNS_I2C_CONTROL_HOLD);
 
 	/* Wait for the address and data to be sent */
-	if (!cdns_i2c_wait(regs, CDNS_I2C_INTERRUPT_COMP))
+	ret = cdns_i2c_wait(regs, CDNS_I2C_INTERRUPT_COMP |
+			    CDNS_I2C_INTERRUPT_ARBLOST);
+	if (!(ret & (CDNS_I2C_INTERRUPT_ARBLOST |
+		     CDNS_I2C_INTERRUPT_COMP)))
 		return -ETIMEDOUT;
+	if (ret & CDNS_I2C_INTERRUPT_ARBLOST)
+		return -EAGAIN;
+
 	return 0;
 }
 
@@ -289,6 +310,7 @@
 	struct cdns_i2c_regs *regs = i2c_bus->regs;
 	int curr_recv_count;
 	int updatetx, hold_quirk;
+	u32 ret;
 
 	/* Check the hardware can handle the requested bytes */
 	if ((recv_count < 0))
@@ -317,7 +339,7 @@
 
 	hold_quirk = (i2c_bus->quirks & CDNS_I2C_BROKEN_HOLD_BIT) && updatetx;
 
-	while (recv_count) {
+	while (recv_count && !is_arbitration_lost(regs)) {
 		while (readl(&regs->status) & CDNS_I2C_STATUS_RXDV) {
 			if (recv_count < CDNS_I2C_FIFO_DEPTH &&
 			    !i2c_bus->hold_flag) {
@@ -366,8 +388,13 @@
 	}
 
 	/* Wait for the address and data to be sent */
-	if (!cdns_i2c_wait(regs, CDNS_I2C_INTERRUPT_COMP))
+	ret = cdns_i2c_wait(regs, CDNS_I2C_INTERRUPT_COMP |
+			    CDNS_I2C_INTERRUPT_ARBLOST);
+	if (!(ret & (CDNS_I2C_INTERRUPT_ARBLOST |
+		     CDNS_I2C_INTERRUPT_COMP)))
 		return -ETIMEDOUT;
+	if (ret & CDNS_I2C_INTERRUPT_ARBLOST)
+		return -EAGAIN;
 
 	return 0;
 }
@@ -376,8 +403,11 @@
 			 int nmsgs)
 {
 	struct i2c_cdns_bus *i2c_bus = dev_get_priv(dev);
-	int ret, count;
+	int ret = 0;
+	int count;
 	bool hold_quirk;
+	struct i2c_msg *message = msg;
+	int num_msgs = nmsgs;
 
 	hold_quirk = !!(i2c_bus->quirks & CDNS_I2C_BROKEN_HOLD_BIT);
 
@@ -403,7 +433,8 @@
 	}
 
 	debug("i2c_xfer: %d messages\n", nmsgs);
-	for (; nmsgs > 0; nmsgs--, msg++) {
+	for (u8 retry = 0; retry < CDNS_I2C_ARB_LOST_MAX_RETRIES &&
+	     nmsgs > 0; nmsgs--, msg++) {
 		debug("i2c_xfer: chip=0x%x, len=0x%x\n", msg->addr, msg->len);
 		if (msg->flags & I2C_M_RD) {
 			ret = cdns_i2c_read_data(i2c_bus, msg->addr, msg->buf,
@@ -412,13 +443,22 @@
 			ret = cdns_i2c_write_data(i2c_bus, msg->addr, msg->buf,
 						  msg->len);
 		}
+		if (ret == -EAGAIN) {
+			msg = message;
+			nmsgs = num_msgs;
+			retry++;
+			printf("%s,arbitration lost, retrying:%d\n", __func__,
+			       retry);
+			continue;
+		}
+
 		if (ret) {
 			debug("i2c_write: error sending\n");
 			return -EREMOTEIO;
 		}
 	}
 
-	return 0;
+	return ret;
 }
 
 static int cdns_i2c_ofdata_to_platdata(struct udevice *dev)