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> -----Original Message-----
> From: Gao Pan [mailto:b54...@freescale.com]
> Sent: Wednesday, August 19, 2015 5:52 PM
> To: w...@the-dreams.de
> Cc: linux-i2c@vger.kernel.org; Li Frank-B20596; Duan Fugang-B38611; Gao
> Pan-B54642; u.kleine-koe...@pengutronix.de; ker...@pengutronix.de
> Subject: [Patch v4] i2c: imx: implement bus recovery
>
> Implement bus recovery methods for i2c-imx so we can recover from
> situations where SCL/SDA are stuck low.
>
> Once i2c bus SCL/SDA are stuck low during transfer, config the i2c
> pinctrl to gpio mode by calling pinctrl sleep set function, and then use
> GPIO to emulate the i2c protocol to send nine dummy clock to recover i2c
> device. After recovery, set i2c pinctrl to default group setting.
>
> Signed-off-by: Fugang Duan <b38...@freescale.com>
> Signed-off-by: Gao Pan <b54...@freescale.com>
> ---
> V2:
> As Uwe Kleine-König's suggestion, the version do below changes:
> -replace of_get_named_gpio() with devm_gpiod_get_optional() -move
> gpio_direction_input() and gpio_direction_output() call to the
> prepare callback
> -use 0 and 1 as return value for the get_scl and get_sda callbacks
>
> V3:
> -replace "...-gpio" with "...-gpios" in i2c binding doc -document the
> requirement of using sleep state to configure
> the pins as gpio in i2c binding doc
> -remove i2c_recover_bus() in i2c_imx_trx_complete() -use GPIOD_OUT_HIGH
> as the parameter of devm_gpiod_get_optional to
> config the gpios as output high
> -add error disposal as devm_gpiod_get_optional meets error
>
> V4:
> -remove include <linux/of_gpio.h>
> -call i2c_recover_bus under the condition of the existing of
> both sda and scl. Drop the sda and scl check in i2c_imx_get_scl,
> i2c_imx_get_sda, i2c_imx_set_scl, i2c_imx_prepare_recovery and
> i2c_imx_prepare_recovery
> -use GPIOD_OUT_IN as the parameter of devm_gpiod_get_optional -remove
> documenting the requirement of using sleep state to configure
> the pins as gpio in i2c binding doc
>
> Documentation/devicetree/bindings/i2c/i2c-imx.txt | 4 +
> drivers/i2c/busses/i2c-imx.c | 94
> +++++++++++++++++++++--
> 2 files changed, 91 insertions(+), 7 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-imx.txt
> b/Documentation/devicetree/bindings/i2c/i2c-imx.txt
> index ce4311d..983996c 100644
> --- a/Documentation/devicetree/bindings/i2c/i2c-imx.txt
> +++ b/Documentation/devicetree/bindings/i2c/i2c-imx.txt
> @@ -14,6 +14,8 @@ Optional properties:
> The absence of the propoerty indicates the default frequency 100 kHz.
> - dmas: A list of two dma specifiers, one for each entry in dma-names.
> - dma-names: should contain "tx" and "rx".
> +- scl-gpios: specify the gpio related to SCL pin
> +- sda-gpios: specify the gpio related to SDA pin
>
> Examples:
>
> @@ -37,4 +39,6 @@ i2c0: i2c@40066000 { /* i2c0 on vf610 */
> dmas = <&edma0 0 50>,
> <&edma0 0 51>;
> dma-names = "rx","tx";
> + scl-gpios = <&gpio5 26 GPIO_ACTIVE_HIGH>;
> + sda-gpios = <&gpio5 27 GPIO_ACTIVE_HIGH>;
> };
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index 4960fc1..aa5db16 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -40,6 +40,7 @@
> #include <linux/dmapool.h>
> #include <linux/err.h>
> #include <linux/errno.h>
> +#include <linux/gpio.h>
> #include <linux/i2c.h>
> #include <linux/init.h>
> #include <linux/interrupt.h>
> @@ -178,6 +179,11 @@ enum imx_i2c_type {
> VF610_I2C,
> };
>
> +struct imx_i2c_pinctrl {
> + struct gpio_desc *sda;
> + struct gpio_desc *scl;
> +};
> +
> struct imx_i2c_hwdata {
> enum imx_i2c_type devtype;
> unsigned regshift;
> @@ -209,6 +215,7 @@ struct imx_i2c_struct {
> unsigned int ifdr; /* IMX_I2C_IFDR */
> unsigned int cur_clk;
> unsigned int bitrate;
> + struct imx_i2c_pinctrl pins;
> const struct imx_i2c_hwdata *hwdata;
>
> struct imx_i2c_dma *dma;
> @@ -439,7 +446,10 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct
> *i2c_imx, int for_busy)
> if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500)))
> {
> dev_dbg(&i2c_imx->adapter.dev,
> "<%s> I2C bus is busy\n", __func__);
> - return -ETIMEDOUT;
> + if (i2c_imx->pins.sda && i2c_imx->pins.scl)
> + return i2c_recover_bus(&i2c_imx->adapter);
> + else
> + return -ETIMEDOUT;
> }
> schedule();
> }
> @@ -963,6 +973,59 @@ out:
> return (result < 0) ? result : num;
> }
>
> +static int i2c_imx_get_scl(struct i2c_adapter *adap) {
> + struct imx_i2c_struct *i2c_imx;
> +
> + i2c_imx = container_of(adap, struct imx_i2c_struct, adapter);
> +
> + return gpiod_get_value(i2c_imx->pins.scl);
> +}
> +
> +static int i2c_imx_get_sda(struct i2c_adapter *adap) {
> + struct imx_i2c_struct *i2c_imx;
> +
> + i2c_imx = container_of(adap, struct imx_i2c_struct, adapter);
> +
> + return gpiod_get_value(i2c_imx->pins.sda);
> +}
> +
> +static void i2c_imx_set_scl(struct i2c_adapter *adap, int val) {
> + struct imx_i2c_struct *i2c_imx;
> +
> + i2c_imx = container_of(adap, struct imx_i2c_struct, adapter);
> + gpiod_set_value(i2c_imx->pins.scl, val); }
> +
> +static void i2c_imx_prepare_recovery(struct i2c_adapter *adap) {
> + struct imx_i2c_struct *i2c_imx;
> +
> + i2c_imx = container_of(adap, struct imx_i2c_struct, adapter);
> + pinctrl_pm_select_sleep_state(&adap->dev);
> + gpiod_direction_input(i2c_imx->pins.sda);
> + gpiod_direction_output(i2c_imx->pins.scl, 1); }
> +
> +static void i2c_imx_unprepare_recovery(struct i2c_adapter *adap) {
> + struct imx_i2c_struct *i2c_imx;
> +
> + i2c_imx = container_of(adap, struct imx_i2c_struct, adapter);
> + pinctrl_pm_select_default_state(&adap->dev);
> +}
> +
> +static struct i2c_bus_recovery_info i2c_imx_bus_recovery_info = {
> + .get_scl = i2c_imx_get_scl,
> + .get_sda = i2c_imx_get_sda,
> + .set_scl = i2c_imx_set_scl,
> + .prepare_recovery = i2c_imx_prepare_recovery,
> + .unprepare_recovery = i2c_imx_unprepare_recovery,
> + .recover_bus = i2c_generic_scl_recovery, };
> +
> static u32 i2c_imx_func(struct i2c_adapter *adapter) {
> return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL @@ -1011,12 +1074,13 @@
> static int i2c_imx_probe(struct platform_device *pdev)
>
> /* Setup i2c_imx driver structure */
> strlcpy(i2c_imx->adapter.name, pdev->name, sizeof(i2c_imx-
> >adapter.name));
> - i2c_imx->adapter.owner = THIS_MODULE;
> - i2c_imx->adapter.algo = &i2c_imx_algo;
> - i2c_imx->adapter.dev.parent = &pdev->dev;
> - i2c_imx->adapter.nr = pdev->id;
> - i2c_imx->adapter.dev.of_node = pdev->dev.of_node;
> - i2c_imx->base = base;
> + i2c_imx->adapter.owner = THIS_MODULE;
> + i2c_imx->adapter.algo = &i2c_imx_algo;
> + i2c_imx->adapter.dev.parent = &pdev->dev;
> + i2c_imx->adapter.nr = pdev->id;
> + i2c_imx->adapter.dev.of_node = pdev->dev.of_node;
> + i2c_imx->adapter.bus_recovery_info = &i2c_imx_bus_recovery_info;
> + i2c_imx->base = base;
>
> /* Get I2C clock */
> i2c_imx->clk = devm_clk_get(&pdev->dev, NULL); @@ -1052,6 +1116,22
> @@ static int i2c_imx_probe(struct platform_device *pdev)
> pm_runtime_set_autosuspend_delay(&pdev->dev, I2C_PM_TIMEOUT);
> pm_runtime_use_autosuspend(&pdev->dev);
>
> + /* Init recover pins */
> + i2c_imx->pins.sda =
> + devm_gpiod_get_optional(&pdev->dev, "sda-gpio", GPIOD_IN);
> + i2c_imx->pins.scl =
> + devm_gpiod_get_optional(&pdev->dev, "scl-gpio", GPIOD_IN);
> +
> + if (IS_ERR(i2c_imx->pins.sda)) {
> + ret = PTR_ERR(i2c_imx->pins.sda);
> + goto clk_disable;
> + }
> +
> + if (IS_ERR(i2c_imx->pins.scl)) {
> + ret = PTR_ERR(i2c_imx->pins.scl);
> + goto clk_disable;
> + }
> +
> /* Set up clock divider */
> i2c_imx->bitrate = IMX_I2C_BIT_RATE;
> ret = of_property_read_u32(pdev->dev.of_node,
> --
> 1.9.1
