[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <1363867800-23861-5-git-send-email-mika.westerberg@linux.intel.com>
Date: Thu, 21 Mar 2013 14:09:58 +0200
From: Mika Westerberg <mika.westerberg@...ux.intel.com>
To: linux-kernel@...r.kernel.org
Cc: linux-i2c@...r.kernel.org, Wolfram Sang <wsa@...-dreams.de>,
ben-linux@...ff.org, Jean Delvare <khali@...ux-fr.org>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Christian Ruppert <christian.ruppert@...lis.com>,
Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: [PATCH 5/7] i2c-designware: enable/disable the controller properly
The correct way to disable or enable the controller is to wait until
DW_IC_ENABLE_STATUS register bit matches the bit we program to the
DW_IC_ENABLE register. This procedure is described in the DesignWare I2C
handbook.
By doing this we can be sure that the controller is in correct state once
the function returns.
Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
---
drivers/i2c/busses/i2c-designware-core.c | 29 +++++++++++++++++++++++------
1 file changed, 23 insertions(+), 6 deletions(-)
diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index 94fd818..0e4f531 100644
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -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 +249,22 @@ 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;
+
+ usleep_range(25, 250);
+ } while (timeout-- > 0);
+
+ 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 +295,7 @@ 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 +362,7 @@ 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 +376,7 @@ 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 +582,7 @@ 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 +717,7 @@ 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 +730,7 @@ 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);
--
1.7.10.4
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists