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> --- .../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; + dev->functionality = I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | -- 1.7.1 -- 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
