On 05/14/2013 08:04 AM, Christian Ruppert wrote:
> This patch makes the SDA hold time configurable through device tree.
>
> [rebased to i2c-current/i2c-next/mainline-3.10-rc1]
>
> Signed-off-by: Christian Ruppert <christian.ruppert@xxxxxxxxxx>
> Signed-off-by: Pierrick Hascoet <pierrick.hascoet@xxxxxxxxxx>
> ---
> .../devicetree/bindings/i2c/i2c-designware.txt | 14 ++++++++++++++
> drivers/i2c/busses/i2c-designware-core.c | 5 +++++
> drivers/i2c/busses/i2c-designware-core.h | 1 +
> drivers/i2c/busses/i2c-designware-platdrv.c | 9 +++++++++
> 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..21fabe7 100644
> --- a/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> +++ b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> @@ -10,6 +10,9 @@ Recommended properties :
>
> - clock-frequency : desired I2C bus clock frequency in Hz.
>
> +Optional properties :
> + - sda-hold-time : should contain the SDA hold time in nanoseconds.
Please specify time units in the property name. Perhaps
i2c-sda-hold-time-ns.
Based on reading the discussion, there is one similar property I have
found: "samsung,i2c-sda-delay = <100>". I wouldn't copy it as it doesn't
tell the units or what the delay is.
Otherwise, looks fine to me.
Rob
> +
> Example :
>
> i2c@f0000 {
> @@ -20,3 +23,14 @@ 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 = <300>;
> + };
> diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
> index 21fbb34..91d422c 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_ENABLE_STATUS 0x9c
> #define DW_IC_COMP_PARAM_1 0xf4
> @@ -332,6 +333,10 @@ 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 8ec9133..589f414 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>
> @@ -120,6 +121,14 @@ static int dw_i2c_probe(struct platform_device *pdev)
> return PTR_ERR(dev->clk);
> clk_prepare_enable(dev->clk);
>
> + if (pdev->dev.of_node) {
> + u32 ht;
> + u32 ic_clk = dev->get_clk_rate_khz(dev);
> +
> + of_property_read_u32(pdev->dev.of_node, "sda-hold-time", &ht);
> + dev->sda_hold_time = ((u64)ic_clk * ht + 500000) / 1000000;
> + }
> +
> dev->functionality =
> I2C_FUNC_I2C |
> I2C_FUNC_10BIT_ADDR |
>
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