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Commit 9803f868 authored by Christian Ruppert's avatar Christian Ruppert Committed by Wolfram Sang
Browse files

i2c-designware: make SDA hold time configurable 



This patch makes the SDA hold time configurable through device tree.

Signed-off-by: default avatarChristian Ruppert <christian.ruppert@abilis.com>
Signed-off-by: default avatarPierrick Hascoet <pierrick.hascoet@abilis.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com> for arch/arc bits
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
parent 4c730a06

Documentation/devicetree/bindings/i2c/i2c-designware.txt

+15 −0
Original line number Diff line number Diff line
@@ -10,6 +10,10 @@ Recommended properties : 


 - clock-frequency : desired I2C bus clock frequency in Hz.



Optional properties :

 - i2c-sda-hold-time-ns : should contain the SDA hold time in nanoseconds.

   This option is only supported in hardware blocks version 1.11a or newer.



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>;

		i2c-sda-hold-time-ns = <300>;

	};

arch/arc/boot/dts/abilis_tb100_dvk.dts

+5 −5
Original line number Diff line number Diff line
@@ -45,19 +45,19 @@ 
		};



		i2c0: i2c@FF120000 {

			sda-hold-time = <432>;

			i2c-sda-hold-time-ns = <432>;

		};

		i2c1: i2c@FF121000 {

			sda-hold-time = <432>;

			i2c-sda-hold-time-ns = <432>;

		};

		i2c2: i2c@FF122000 {

			sda-hold-time = <432>;

			i2c-sda-hold-time-ns = <432>;

		};

		i2c3: i2c@FF123000 {

			sda-hold-time = <432>;

			i2c-sda-hold-time-ns = <432>;

		};

		i2c4: i2c@FF124000 {

			sda-hold-time = <432>;

			i2c-sda-hold-time-ns = <432>;

		};



		leds {

arch/arc/boot/dts/abilis_tb101_dvk.dts

+5 −5
Original line number Diff line number Diff line
@@ -45,19 +45,19 @@ 
		};



		i2c0: i2c@FF120000 {

			sda-hold-time = <432>;

			i2c-sda-hold-time-ns = <432>;

		};

		i2c1: i2c@FF121000 {

			sda-hold-time = <432>;

			i2c-sda-hold-time-ns = <432>;

		};

		i2c2: i2c@FF122000 {

			sda-hold-time = <432>;

			i2c-sda-hold-time-ns = <432>;

		};

		i2c3: i2c@FF123000 {

			sda-hold-time = <432>;

			i2c-sda-hold-time-ns = <432>;

		};

		i2c4: i2c@FF124000 {

			sda-hold-time = <432>;

			i2c-sda-hold-time-ns = <432>;

		};



		leds {

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

+13 −0
Original line number Diff line number Diff line
@@ -67,9 +67,12 @@ 
#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_ENABLE_STATUS	0x9c

#define DW_IC_COMP_PARAM_1	0xf4

#define DW_IC_COMP_VERSION	0xf8

#define DW_IC_SDA_HOLD_MIN_VERS	0x3131312A

#define DW_IC_COMP_TYPE		0xfc

#define DW_IC_COMP_TYPE_VALUE	0x44570140
@@ -332,6 +335,16 @@ 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) {

		reg = dw_readl(dev, DW_IC_COMP_VERSION);

		if (reg >= DW_IC_SDA_HOLD_MIN_VERS)

			dw_writel(dev, dev->sda_hold_time, DW_IC_SDA_HOLD);

		else

			dev_warn(dev->dev,

				"Hardware too old to adjust SDA hold time.");

	}



	/* 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);

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

+1 −0
Original line number Diff line number Diff line
@@ -90,6 +90,7 @@ struct dw_i2c_dev { 
	unsigned int		tx_fifo_depth;

	unsigned int		rx_fifo_depth;

	int			rx_outstanding;

	u32			sda_hold_time;

};



#define ACCESS_SWAP		0x00000001