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path: root/target/linux/cns3xxx/patches-3.3/440-i2c_retry.patch
blob: 707de82bab55ae43237d581cc4f3766121cd203e (plain)
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--- a/drivers/i2c/busses/i2c-cns3xxx.c
+++ b/drivers/i2c/busses/i2c-cns3xxx.c
@@ -2,8 +2,9 @@
  * Cavium CNS3xxx I2C Host Controller
  *
  * Copyright 2010 Cavium Network
- * Copyright 2011 Gateworks Corporation
+ * Copyright 2012 Gateworks Corporation
  *		  Chris Lang <clang@gateworks.com>
+ *        Tim Harvey <tharvey@gateworks.com>
  *
  * This file is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License, Version 2, as
@@ -63,13 +64,15 @@
 #define STATE_ERROR		2
 
 struct cns3xxx_i2c {
-	void __iomem *base;
-	wait_queue_head_t wait;
-	struct i2c_adapter adap;
-	struct i2c_msg *msg;
-	int state;		/* see STATE_ */
-	int rd_wr_len;
-	u8 *buf;
+	struct device		*dev;
+	void __iomem		*base;		/* virtual */
+	wait_queue_head_t	wait;
+	struct i2c_adapter	adap;
+	struct i2c_msg		*msg;
+	u8			state;		/* see STATE_ */
+	u8			error;		/* see TWI_STATUS register */
+	int			rd_wr_len;
+	u8			*buf;
 };
 
 static u32 cns3xxx_i2c_func(struct i2c_adapter *adap)
@@ -150,14 +153,18 @@ cns3xxx_i2c_xfer_msg(struct i2c_adapter
 
 		// Start the Transfer
 		i2c->state = 0;		// Clear out the State
+		i2c->error = 0;
 		I2C_CONTROLLER_REG |= (1 << 6);
 
 		if (wait_event_timeout(i2c->wait, (i2c->state == STATE_ERROR) ||
 				(i2c->state == STATE_DONE), TWI_TIMEOUT)) {
 			if (i2c->state == STATE_ERROR) {
-				return -EIO;
+				dev_dbg(i2c->dev, "controller error: 0x%2x", i2c->error);
+				return -EAGAIN; // try again
 			}
 		} else {
+			dev_err(i2c->dev, "controller timed out "
+				"waiting for start condition to finish\n");
 			return -ETIMEDOUT;
 		}
 	}
@@ -238,6 +245,7 @@ static irqreturn_t cns3xxx_i2c_isr(int i
 
 	if (stat & I2C_BUS_ERROR_FLAG) {
 		i2c->state = STATE_ERROR;
+		i2c->error = (I2C_INTERRUPT_STATUS_REG & 0xff00)>>8;
 	} else {
 		if (i2c->msg->flags & I2C_M_RD) {
 			for (i = 0; i <= i2c->rd_wr_len; i++)
@@ -280,6 +288,7 @@ static int __devinit cns3xxx_i2c_probe(s
 		goto request_mem_failed;
 	}
 
+	i2c->dev = &pdev->dev;
 	i2c->base = ioremap(res->start, res->end - res->start + 1);
 	if (!i2c->base) {
 		dev_err(&pdev->dev, "Unable to map registers\n");