1 files changed, 78 insertions, 24 deletions

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index fb3b4f8..3056ea4 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -26,6 +26,8 @@
 #include <linux/delay.h>
 #include <linux/slab.h>
 #include <linux/i2c-tegra.h>
+#include <linux/of_i2c.h>
+#include <linux/module.h>
 
 #include <asm/unaligned.h>
 
@@ -269,14 +271,30 @@ static int tegra_i2c_fill_tx_fifo(struct tegra_i2c_dev *i2c_dev)
 
 	/* Rounds down to not include partial word at the end of buf */
 	words_to_transfer = buf_remaining / BYTES_PER_FIFO_WORD;
-	if (words_to_transfer > tx_fifo_avail)
-		words_to_transfer = tx_fifo_avail;
 
-	i2c_writesl(i2c_dev, buf, I2C_TX_FIFO, words_to_transfer);
-
-	buf += words_to_transfer * BYTES_PER_FIFO_WORD;
-	buf_remaining -= words_to_transfer * BYTES_PER_FIFO_WORD;
-	tx_fifo_avail -= words_to_transfer;
+	/* It's very common to have < 4 bytes, so optimize that case. */
+	if (words_to_transfer) {
+		if (words_to_transfer > tx_fifo_avail)
+			words_to_transfer = tx_fifo_avail;
+
+		/*
+		 * Update state before writing to FIFO.  If this casues us
+		 * to finish writing all bytes (AKA buf_remaining goes to 0) we
+		 * have a potential for an interrupt (PACKET_XFER_COMPLETE is
+		 * not maskable).  We need to make sure that the isr sees
+		 * buf_remaining as 0 and doesn't call us back re-entrantly.
+		 */
+		buf_remaining -= words_to_transfer * BYTES_PER_FIFO_WORD;
+		tx_fifo_avail -= words_to_transfer;
+		i2c_dev->msg_buf_remaining = buf_remaining;
+		i2c_dev->msg_buf = buf +
+			words_to_transfer * BYTES_PER_FIFO_WORD;
+		barrier();
+
+		i2c_writesl(i2c_dev, buf, I2C_TX_FIFO, words_to_transfer);
+
+		buf += words_to_transfer * BYTES_PER_FIFO_WORD;
+	}
 
 	/*
 	 * If there is a partial word at the end of buf, handle it manually to
@@ -286,14 +304,15 @@ static int tegra_i2c_fill_tx_fifo(struct tegra_i2c_dev *i2c_dev)
 	if (tx_fifo_avail > 0 && buf_remaining > 0) {
 		BUG_ON(buf_remaining > 3);
 		memcpy(&val, buf, buf_remaining);
+
+		/* Again update before writing to FIFO to make sure isr sees. */
+		i2c_dev->msg_buf_remaining = 0;
+		i2c_dev->msg_buf = NULL;
+		barrier();
+
 		i2c_writel(i2c_dev, val, I2C_TX_FIFO);
-		buf_remaining = 0;
-		tx_fifo_avail--;
 	}
 
-	BUG_ON(tx_fifo_avail > 0 && buf_remaining > 0);
-	i2c_dev->msg_buf_remaining = buf_remaining;
-	i2c_dev->msg_buf = buf;
 	return 0;
 }
 
@@ -322,7 +341,11 @@ static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev)
 	u32 val;
 	int err = 0;
 
-	clk_enable(i2c_dev->clk);
+	err = clk_enable(i2c_dev->clk);
+	if (err < 0) {
+		dev_err(i2c_dev->dev, "Clock enable failed %d\n", err);
+		return err;
+	}
 
 	tegra_periph_reset_assert(i2c_dev->clk);
 	udelay(2);
@@ -382,8 +405,6 @@ static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
 			disable_irq_nosync(i2c_dev->irq);
 			i2c_dev->irq_disabled = 1;
 		}
-
-		complete(&i2c_dev->msg_complete);
 		goto err;
 	}
 
@@ -392,7 +413,6 @@ static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
 			i2c_dev->msg_err |= I2C_ERR_NO_ACK;
 		if (status & I2C_INT_ARBITRATION_LOST)
 			i2c_dev->msg_err |= I2C_ERR_ARBITRATION_LOST;
-		complete(&i2c_dev->msg_complete);
 		goto err;
 	}
 
@@ -410,13 +430,14 @@ static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
 			tegra_i2c_mask_irq(i2c_dev, I2C_INT_TX_FIFO_DATA_REQ);
 	}
 
-	if ((status & I2C_INT_PACKET_XFER_COMPLETE) &&
-			!i2c_dev->msg_buf_remaining)
-		complete(&i2c_dev->msg_complete);
-
 	i2c_writel(i2c_dev, status, I2C_INT_STATUS);
 	if (i2c_dev->is_dvc)
 		dvc_writel(i2c_dev, DVC_STATUS_I2C_DONE_INTR, DVC_STATUS);
+
+	if (status & I2C_INT_PACKET_XFER_COMPLETE) {
+		BUG_ON(i2c_dev->msg_buf_remaining);
+		complete(&i2c_dev->msg_complete);
+	}
 	return IRQ_HANDLED;
 err:
 	/* An error occurred, mask all interrupts */
@@ -426,6 +447,8 @@ err:
 	i2c_writel(i2c_dev, status, I2C_INT_STATUS);
 	if (i2c_dev->is_dvc)
 		dvc_writel(i2c_dev, DVC_STATUS_I2C_DONE_INTR, DVC_STATUS);
+
+	complete(&i2c_dev->msg_complete);
 	return IRQ_HANDLED;
 }
 
@@ -517,7 +540,12 @@ static int tegra_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 	if (i2c_dev->is_suspended)
 		return -EBUSY;
 
-	clk_enable(i2c_dev->clk);
+	ret = clk_enable(i2c_dev->clk);
+	if (ret < 0) {
+		dev_err(i2c_dev->dev, "Clock enable failed %d\n", ret);
+		return ret;
+	}
+
 	for (i = 0; i < num; i++) {
 		int stop = (i == (num - 1)) ? 1  : 0;
 		ret = tegra_i2c_xfer_msg(i2c_dev, &msgs[i], stop);
@@ -530,7 +558,7 @@ static int tegra_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 
 static u32 tegra_i2c_func(struct i2c_adapter *adap)
 {
-	return I2C_FUNC_I2C;
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 }
 
 static const struct i2c_algorithm tegra_i2c_algo = {
@@ -546,7 +574,8 @@ static int tegra_i2c_probe(struct platform_device *pdev)
 	struct resource *iomem;
 	struct clk *clk;
 	struct clk *i2c_clk;
-	void *base;
+	const unsigned int *prop;
+	void __iomem *base;
 	int irq;
 	int ret = 0;
 
@@ -603,7 +632,17 @@ static int tegra_i2c_probe(struct platform_device *pdev)
 	i2c_dev->irq = irq;
 	i2c_dev->cont_id = pdev->id;
 	i2c_dev->dev = &pdev->dev;
-	i2c_dev->bus_clk_rate = pdata ? pdata->bus_clk_rate : 100000;
+
+	i2c_dev->bus_clk_rate = 100000; /* default clock rate */
+	if (pdata) {
+		i2c_dev->bus_clk_rate = pdata->bus_clk_rate;
+
+	} else if (i2c_dev->dev->of_node) {    /* if there is a device tree node ... */
+		prop = of_get_property(i2c_dev->dev->of_node,
+				"clock-frequency", NULL);
+		if (prop)
+			i2c_dev->bus_clk_rate = be32_to_cpup(prop);
+	}
 
 	if (pdev->id == 3)
 		i2c_dev->is_dvc = 1;
@@ -633,6 +672,7 @@ static int tegra_i2c_probe(struct platform_device *pdev)
 	i2c_dev->adapter.algo = &tegra_i2c_algo;
 	i2c_dev->adapter.dev.parent = &pdev->dev;
 	i2c_dev->adapter.nr = pdev->id;
+	i2c_dev->adapter.dev.of_node = pdev->dev.of_node;
 
 	ret = i2c_add_numbered_adapter(&i2c_dev->adapter);
 	if (ret) {
@@ -640,6 +680,8 @@ static int tegra_i2c_probe(struct platform_device *pdev)
 		goto err_free_irq;
 	}
 
+	of_i2c_register_devices(&i2c_dev->adapter);
+
 	return 0;
 err_free_irq:
 	free_irq(i2c_dev->irq, i2c_dev);
@@ -704,6 +746,17 @@ static int tegra_i2c_resume(struct platform_device *pdev)
 }
 #endif
 
+#if defined(CONFIG_OF)
+/* Match table for of_platform binding */
+static const struct of_device_id tegra_i2c_of_match[] __devinitconst = {
+	{ .compatible = "nvidia,tegra20-i2c", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, tegra_i2c_of_match);
+#else
+#define tegra_i2c_of_match NULL
+#endif
+
 static struct platform_driver tegra_i2c_driver = {
 	.probe   = tegra_i2c_probe,
 	.remove  = tegra_i2c_remove,
@@ -714,6 +767,7 @@ static struct platform_driver tegra_i2c_driver = {
 	.driver  = {
 		.name  = "tegra-i2c",
 		.owner = THIS_MODULE,
+		.of_match_table = tegra_i2c_of_match,
 	},
 };