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| author | Mika Westerberg <mika.westerberg@linux.intel.com> | 2013-04-10 00:36:40 +0000 |
|---|---|---|
| committer | Wolfram Sang <wsa@the-dreams.de> | 2013-04-15 18:17:51 +0200 |
| commit | 3ca4ed8715a6677ce2cdd7aa471685e653b5114d (patch) | |
| tree | 3d9e689ceb242d4ff355262a5ea6ae59a2f967e3 /drivers/i2c | |
| parent | efe7d640ef486c4c0c305641dbcacc6918542b76 (diff) | |
| download | linux-3ca4ed8715a6677ce2cdd7aa471685e653b5114d.tar.gz linux-3ca4ed8715a6677ce2cdd7aa471685e653b5114d.tar.bz2 linux-3ca4ed8715a6677ce2cdd7aa471685e653b5114d.zip | |
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: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/busses/i2c-designware-core.c | 34 |
1 files changed, 28 insertions, 6 deletions
diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c index 94fd81875409..5cc4ebf29b0a 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 +249,27 @@ 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); |