On Mon, Feb 18, 2013 at 11:14:27AM +0100, Christian Ruppert wrote: > This patch makes the SDA hold time configurable through device tree. > It was tested on a hybrid of i2c/next and arc-3.8-baseline (see > https://github.com/foss-for-synopsys-dwc-arc-processors/linux/commits/arc-3.8-baseline) since our platform is ARC based and this architecture is not yet > supported by i2c/next. > > Signed-off-by: Christian Ruppert <christian.ruppert@xxxxxxxxxx> > Signed-off-by: Pierrick Hascoet <pierrick.hascoet@xxxxxxxxxx> Looks good but I have still one minor comment. See below. > --- > .../devicetree/bindings/i2c/i2c-designware.txt | 15 +++++++++++++++ > drivers/i2c/busses/i2c-designware-core.c | 5 +++++ > drivers/i2c/busses/i2c-designware-core.h | 1 + > drivers/i2c/busses/i2c-designware-platdrv.c | 8 ++++++++ > 4 files changed, 29 insertions(+), 0 deletions(-) > > diff --git a/Documentation/devicetree/bindings/i2c/i2c-designware.txt b/Documentation/devicetree/bindings/i2c/i2c-designware.txt > index e42a2ee..fb2eac8 100644 > --- a/Documentation/devicetree/bindings/i2c/i2c-designware.txt > +++ b/Documentation/devicetree/bindings/i2c/i2c-designware.txt > @@ -10,6 +10,10 @@ Recommended properties : > > - clock-frequency : desired I2C bus clock frequency in Hz. > > +Optional properties : > + - sda-hold-time : If this property is present, the register SDA_HOLD will > + be initialised with its value. > + > Example : > > i2c@f0000 { > @@ -20,3 +24,14 @@ Example : > interrupts = <11>; > clock-frequency = <400000>; > }; > + > + i2c@1120000 { > + #address-cells = <1>; > + #size-cells = <0>; > + compatible = "snps,designware-i2c"; > + reg = <0x1120000 0x1000>; > + interrupt-parent = <&ictl>; > + interrupts = <12 1>; > + clock-frequency = <400000>; > + sda-hold-time = <0x64>; > + }; > diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c > index 94fd818..ba40e14 100644 > --- a/drivers/i2c/busses/i2c-designware-core.c > +++ b/drivers/i2c/busses/i2c-designware-core.c > @@ -67,6 +67,7 @@ > #define DW_IC_STATUS 0x70 > #define DW_IC_TXFLR 0x74 > #define DW_IC_RXFLR 0x78 > +#define DW_IC_SDA_HOLD 0x7c > #define DW_IC_TX_ABRT_SOURCE 0x80 > #define DW_IC_COMP_PARAM_1 0xf4 > #define DW_IC_COMP_TYPE 0xfc > @@ -310,6 +311,10 @@ int i2c_dw_init(struct dw_i2c_dev *dev) > dw_writel(dev, lcnt, DW_IC_FS_SCL_LCNT); > dev_dbg(dev->dev, "Fast-mode HCNT:LCNT = %d:%d\n", hcnt, lcnt); > > + /* Configure SDA Hold Time if required */ > + if (dev->sda_hold_time) > + dw_writel(dev, dev->sda_hold_time, DW_IC_SDA_HOLD); > + > /* Configure Tx/Rx FIFO threshold levels */ > dw_writel(dev, dev->tx_fifo_depth - 1, DW_IC_TX_TL); > dw_writel(dev, 0, DW_IC_RX_TL); > diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h > index 9c1840e..33dfec3 100644 > --- a/drivers/i2c/busses/i2c-designware-core.h > +++ b/drivers/i2c/busses/i2c-designware-core.h > @@ -88,6 +88,7 @@ struct dw_i2c_dev { > u32 master_cfg; > unsigned int tx_fifo_depth; > unsigned int rx_fifo_depth; > + u32 sda_hold_time; > }; > > #define ACCESS_SWAP 0x00000001 > diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c > index d2a33e9..9cb0100 100644 > --- a/drivers/i2c/busses/i2c-designware-platdrv.c > +++ b/drivers/i2c/busses/i2c-designware-platdrv.c > @@ -34,6 +34,7 @@ > #include <linux/sched.h> > #include <linux/err.h> > #include <linux/interrupt.h> > +#include <linux/of.h> > #include <linux/of_i2c.h> > #include <linux/platform_device.h> > #include <linux/pm.h> > @@ -136,6 +137,13 @@ static int dw_i2c_probe(struct platform_device *pdev) > } > clk_prepare_enable(dev->clk); > > + if (pdev->dev.of_node) { > + if (of_property_read_u32(pdev->dev.of_node, "sda-hold-time", > + &dev->sda_hold_time)) > + dev->sda_hold_time = 0; > + } else > + dev->sda_hold_time = 0; You don't need to explicitly set this to 0 because the dev object is allocated using kzalloc() which already zeroes out the whole structure. -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
