RE: [PATCH V2 10/18] i2c: imx-lpi2c: add bus recovery feature

[Aisheng Dong <aisheng.dong@nxp.com>]

> From: Clark Wang <xiaoning.wang@nxp.com>
> Sent: Tuesday, April 6, 2021 7:33 PM
> 
> Add bus recovery feature for LPI2C.
> Need add gpio pinctrl, scl-gpios and sda-gpios configuration in dts.
> 
> Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
> ---
> V2 changes:
>  - No change. Add dt-bindings in the next patch.

Dt binding patch should be sent before driver change

> ---
>  drivers/i2c/busses/i2c-imx-lpi2c.c | 83 ++++++++++++++++++++++++++++++
>  1 file changed, 83 insertions(+)
> 
> diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c
> b/drivers/i2c/busses/i2c-imx-lpi2c.c
> index 77ceb743b282..77dd6ee5a4a8 100644
> --- a/drivers/i2c/busses/i2c-imx-lpi2c.c
> +++ b/drivers/i2c/busses/i2c-imx-lpi2c.c
> @@ -18,6 +18,7 @@
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/of_device.h>
> +#include <linux/of_gpio.h>
>  #include <linux/pinctrl/consumer.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_runtime.h>
> @@ -108,6 +109,11 @@ struct lpi2c_imx_struct {
>  	unsigned int		txfifosize;
>  	unsigned int		rxfifosize;
>  	enum lpi2c_imx_mode	mode;
> +
> +	struct i2c_bus_recovery_info rinfo;
> +	struct pinctrl *pinctrl;
> +	struct pinctrl_state *pinctrl_pins_default;
> +	struct pinctrl_state *pinctrl_pins_gpio;
>  };
> 
>  static void lpi2c_imx_intctrl(struct lpi2c_imx_struct *lpi2c_imx, @@ -135,6
> +141,8 @@ static int lpi2c_imx_bus_busy(struct lpi2c_imx_struct *lpi2c_imx)
> 
>  		if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) {
>  			dev_dbg(&lpi2c_imx->adapter.dev, "bus not work\n");
> +			if (lpi2c_imx->adapter.bus_recovery_info)
> +				i2c_recover_bus(&lpi2c_imx->adapter);
>  			return -ETIMEDOUT;
>  		}
>  		schedule();
> @@ -192,6 +200,8 @@ static void lpi2c_imx_stop(struct lpi2c_imx_struct
> *lpi2c_imx)
> 
>  		if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) {
>  			dev_dbg(&lpi2c_imx->adapter.dev, "stop timeout\n");
> +			if (lpi2c_imx->adapter.bus_recovery_info)
> +				i2c_recover_bus(&lpi2c_imx->adapter);
>  			break;
>  		}
>  		schedule();
> @@ -329,6 +339,8 @@ static int lpi2c_imx_txfifo_empty(struct
> lpi2c_imx_struct *lpi2c_imx)
> 
>  		if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) {
>  			dev_dbg(&lpi2c_imx->adapter.dev, "txfifo empty timeout\n");
> +			if (lpi2c_imx->adapter.bus_recovery_info)
> +				i2c_recover_bus(&lpi2c_imx->adapter);
>  			return -ETIMEDOUT;
>  		}
>  		schedule();
> @@ -528,6 +540,71 @@ static irqreturn_t lpi2c_imx_isr(int irq, void *dev_id)
>  	return IRQ_HANDLED;
>  }
> 
> +static void lpi2c_imx_prepare_recovery(struct i2c_adapter *adap) {
> +	struct lpi2c_imx_struct *lpi2c_imx;
> +
> +	lpi2c_imx = container_of(adap, struct lpi2c_imx_struct, adapter);
> +
> +	pinctrl_select_state(lpi2c_imx->pinctrl,
> +lpi2c_imx->pinctrl_pins_gpio); }
> +
> +static void lpi2c_imx_unprepare_recovery(struct i2c_adapter *adap) {
> +	struct lpi2c_imx_struct *lpi2c_imx;
> +
> +	lpi2c_imx = container_of(adap, struct lpi2c_imx_struct, adapter);
> +
> +	pinctrl_select_state(lpi2c_imx->pinctrl,
> +lpi2c_imx->pinctrl_pins_default); }
> +
> +/*
> + * We switch SCL and SDA to their GPIO function and do some bitbanging
> + * for bus recovery. These alternative pinmux settings can be
> + * described in the device tree by a separate pinctrl state "gpio". If
> + * this is missing this is not a big problem, the only implication is
> + * that we can't do bus recovery.
> + */
> +static int lpi2c_imx_init_recovery_info(struct lpi2c_imx_struct *lpi2c_imx,
> +		struct platform_device *pdev)
> +{
> +	struct i2c_bus_recovery_info *rinfo = &lpi2c_imx->rinfo;
> +
> +	lpi2c_imx->pinctrl = devm_pinctrl_get(&pdev->dev);
> +	if (!lpi2c_imx->pinctrl || IS_ERR(lpi2c_imx->pinctrl)) {
> +		dev_info(&pdev->dev, "can't get pinctrl, bus recovery not
> supported\n");
> +		return PTR_ERR(lpi2c_imx->pinctrl);
> +	}
> +
> +	lpi2c_imx->pinctrl_pins_default = pinctrl_lookup_state(lpi2c_imx->pinctrl,
> +			PINCTRL_STATE_DEFAULT);
> +	lpi2c_imx->pinctrl_pins_gpio = pinctrl_lookup_state(lpi2c_imx->pinctrl,
> +			"gpio");
> +	rinfo->sda_gpiod = devm_gpiod_get(&pdev->dev, "sda", GPIOD_IN);
> +	rinfo->scl_gpiod = devm_gpiod_get(&pdev->dev, "scl",
> +GPIOD_OUT_HIGH_OPEN_DRAIN);
> +
> +	if (PTR_ERR(rinfo->sda_gpiod) == -EPROBE_DEFER ||
> +	    PTR_ERR(rinfo->scl_gpiod) == -EPROBE_DEFER) {
> +		return -EPROBE_DEFER;
> +	} else if (IS_ERR(rinfo->sda_gpiod) ||
> +		   IS_ERR(rinfo->scl_gpiod) ||
> +		   IS_ERR(lpi2c_imx->pinctrl_pins_default) ||
> +		   IS_ERR(lpi2c_imx->pinctrl_pins_gpio)) {
> +		dev_dbg(&pdev->dev, "recovery information incomplete\n");
> +		return 0;
> +	}
> +
> +	dev_info(&pdev->dev, "using scl%s for recovery\n",
> +		 rinfo->sda_gpiod ? ",sda" : "");
> +
> +	rinfo->prepare_recovery = lpi2c_imx_prepare_recovery;
> +	rinfo->unprepare_recovery = lpi2c_imx_unprepare_recovery;
> +	rinfo->recover_bus = i2c_generic_scl_recovery;
> +	lpi2c_imx->adapter.bus_recovery_info = rinfo;
> +
> +	return 0;
> +}
> +
>  static u32 lpi2c_imx_func(struct i2c_adapter *adapter)  {
>  	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | @@ -632,6 +709,12
> @@ static int lpi2c_imx_probe(struct platform_device *pdev)
>  	lpi2c_imx->txfifosize = 1 << (temp & 0x0f);
>  	lpi2c_imx->rxfifosize = 1 << ((temp >> 8) & 0x0f);
> 
> +	/* Init optional bus recovery function */
> +	ret = lpi2c_imx_init_recovery_info(lpi2c_imx, pdev);
> +	/* Give it another chance if pinctrl used is not ready yet */
> +	if (ret == -EPROBE_DEFER)
> +		goto rpm_disable;
> +
>  	ret = i2c_add_adapter(&lpi2c_imx->adapter);
>  	if (ret)
>  		goto rpm_disable;
> --
> 2.25.1

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