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Commit 3ca4ed87 authored by Mika Westerberg's avatar Mika Westerberg Committed by Wolfram Sang
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i2c-designware: enable/disable the controller properly 



The correct way to disable or enable the controller is to wait until the
DW_IC_ENABLE_STATUS register bit matches the bit we program into DW_IC_ENABLE
register. This procedure is described in the DesignWare I2C databook.

By doing this we can be sure that the controller is in correct state once
the function returns.

Signed-off-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
parent efe7d640

drivers/i2c/busses/i2c-designware-core.c

+28 −6
Original line number Diff line number Diff line
@@ -68,6 +68,7 @@ 
#define DW_IC_TXFLR		0x74

#define DW_IC_RXFLR		0x78

#define DW_IC_TX_ABRT_SOURCE	0x80

#define DW_IC_ENABLE_STATUS	0x9c

#define DW_IC_COMP_PARAM_1	0xf4

#define DW_IC_COMP_TYPE		0xfc

#define DW_IC_COMP_TYPE_VALUE	0x44570140
@@ -248,6 +249,27 @@ static u32 i2c_dw_scl_lcnt(u32 ic_clk, u32 tLOW, u32 tf, int offset) 
	return ((ic_clk * (tLOW + tf) + 5000) / 10000) - 1 + offset;

}



static void __i2c_dw_enable(struct dw_i2c_dev *dev, bool enable)

{

	int timeout = 100;



	do {

		dw_writel(dev, enable, DW_IC_ENABLE);

		if ((dw_readl(dev, DW_IC_ENABLE_STATUS) & 1) == enable)

			return;



		/*

		 * Wait 10 times the signaling period of the highest I2C

		 * transfer supported by the driver (for 400KHz this is

		 * 25us) as described in the DesignWare I2C databook.

		 */

		usleep_range(25, 250);

	} while (timeout--);



	dev_warn(dev->dev, "timeout in %sabling adapter\n",

		 enable ? "en" : "dis");

}



/**

 * i2c_dw_init() - initialize the designware i2c master hardware

 * @dev: device private data
@@ -278,7 +300,7 @@ int i2c_dw_init(struct dw_i2c_dev *dev) 
	}



	/* Disable the adapter */

	dw_writel(dev, 0, DW_IC_ENABLE);

	__i2c_dw_enable(dev, false);



	/* set standard and fast speed deviders for high/low periods */
@@ -345,7 +367,7 @@ static void i2c_dw_xfer_init(struct dw_i2c_dev *dev) 
	u32 ic_con;



	/* Disable the adapter */

	dw_writel(dev, 0, DW_IC_ENABLE);

	__i2c_dw_enable(dev, false);



	/* set the slave (target) address */

	dw_writel(dev, msgs[dev->msg_write_idx].addr, DW_IC_TAR);
@@ -359,7 +381,7 @@ static void i2c_dw_xfer_init(struct dw_i2c_dev *dev) 
	dw_writel(dev, ic_con, DW_IC_CON);



	/* Enable the adapter */

	dw_writel(dev, 1, DW_IC_ENABLE);

	__i2c_dw_enable(dev, true);



	/* Enable interrupts */

	dw_writel(dev, DW_IC_INTR_DEFAULT_MASK, DW_IC_INTR_MASK);
@@ -565,7 +587,7 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) 
	/* no error */

	if (likely(!dev->cmd_err)) {

		/* Disable the adapter */

		dw_writel(dev, 0, DW_IC_ENABLE);

		__i2c_dw_enable(dev, false);

		ret = num;

		goto done;

	}
@@ -700,7 +722,7 @@ EXPORT_SYMBOL_GPL(i2c_dw_isr); 
void i2c_dw_enable(struct dw_i2c_dev *dev)

{

       /* Enable the adapter */

	dw_writel(dev, 1, DW_IC_ENABLE);

	__i2c_dw_enable(dev, true);

}

EXPORT_SYMBOL_GPL(i2c_dw_enable);
@@ -713,7 +735,7 @@ EXPORT_SYMBOL_GPL(i2c_dw_is_enabled); 
void i2c_dw_disable(struct dw_i2c_dev *dev)

{

	/* Disable controller */

	dw_writel(dev, 0, DW_IC_ENABLE);

	__i2c_dw_enable(dev, false);



	/* Disable all interupts */

	dw_writel(dev, 0, DW_IC_INTR_MASK);