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 <B38611@freescale.com>
Signed-off-by: Gao Pan <b54642@freescale.com>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

diff --git a/Documentation/devicetree/bindings/i2c/i2c-imx.txt b/Documentation/devicetree/bindings/i2c/i2c-imx.txt
index ce4311d726ae5e4a414e6240cc8832e876a9c24e..eab5836ba7f98a10dedeb8d30b997cc45470944d 100644 (file)
--- a/Documentation/devicetree/bindings/i2c/i2c-imx.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-imx.txt
@@ -14,6 +14,10 @@ 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
+- pinctrl: add extra pinctrl to configure i2c pins to gpio function for i2c
+  bus recovery, call it "gpio" state
 
 Examples:
 
@@ -37,4 +41,9 @@ i2c0: i2c@40066000 { /* i2c0 on vf610 */
        dmas = <&edma0 0 50>,
                <&edma0 0 51>;
        dma-names = "rx","tx";
+       pinctrl-names = "default", "gpio";
+       pinctrl-0 = <&pinctrl_i2c1>;
+       pinctrl-1 = <&pinctrl_i2c1_gpio>;
+       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 785aa674a4da19524a94be3aa6c9b5d66cc8058c..8d46e74c720a77ed839d3450af2d962ac5209a35 100644 (file)
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -49,6 +49,7 @@
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/of_dma.h>
+#include <linux/of_gpio.h>
 #include <linux/platform_data/i2c-imx.h>
 #include <linux/platform_device.h>
 #include <linux/sched.h>
@@ -207,6 +208,11 @@ struct imx_i2c_struct {
        unsigned int            cur_clk;
        unsigned int            bitrate;
        const struct imx_i2c_hwdata     *hwdata;
+       struct i2c_bus_recovery_info rinfo;
+
+       struct pinctrl *pinctrl;
+       struct pinctrl_state *pinctrl_pins_default;
+       struct pinctrl_state *pinctrl_pins_gpio;
 
        struct imx_i2c_dma      *dma;
 };
@@ -896,6 +902,13 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
 
        /* Start I2C transfer */
        result = i2c_imx_start(i2c_imx);
+       if (result) {
+               if (i2c_imx->adapter.bus_recovery_info) {
+                       i2c_recover_bus(&i2c_imx->adapter);
+                       result = i2c_imx_start(i2c_imx);
+               }
+       }
+
        if (result)
                goto fail0;
 
@@ -956,6 +969,55 @@ fail0:
        return (result < 0) ? result : num;
 }
 
+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_select_state(i2c_imx->pinctrl, i2c_imx->pinctrl_pins_gpio);
+}
+
+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_select_state(i2c_imx->pinctrl, i2c_imx->pinctrl_pins_default);
+}
+
+static void i2c_imx_init_recovery_info(struct imx_i2c_struct *i2c_imx,
+               struct platform_device *pdev)
+{
+       struct i2c_bus_recovery_info *rinfo = &i2c_imx->rinfo;
+
+       i2c_imx->pinctrl_pins_default = pinctrl_lookup_state(i2c_imx->pinctrl,
+                       PINCTRL_STATE_DEFAULT);
+       i2c_imx->pinctrl_pins_gpio = pinctrl_lookup_state(i2c_imx->pinctrl,
+                       "gpio");
+       rinfo->sda_gpio = of_get_named_gpio_flags(pdev->dev.of_node,
+                       "sda-gpios", 0, NULL);
+       rinfo->scl_gpio = of_get_named_gpio_flags(pdev->dev.of_node,
+                       "scl-gpios", 0, NULL);
+
+       if (!gpio_is_valid(rinfo->sda_gpio) ||
+           !gpio_is_valid(rinfo->scl_gpio) ||
+           IS_ERR(i2c_imx->pinctrl_pins_default) ||
+           IS_ERR(i2c_imx->pinctrl_pins_gpio)) {
+               dev_dbg(&pdev->dev, "recovery information incomplete\n");
+               return;
+       }
+
+       dev_dbg(&pdev->dev, "using scl-gpio %d and sda-gpio %d for recovery\n",
+                       rinfo->sda_gpio, rinfo->scl_gpio);
+
+       rinfo->prepare_recovery = i2c_imx_prepare_recovery;
+       rinfo->unprepare_recovery = i2c_imx_unprepare_recovery;
+       rinfo->recover_bus = i2c_generic_gpio_recovery;
+       i2c_imx->adapter.bus_recovery_info = rinfo;
+}
+
 static u32 i2c_imx_func(struct i2c_adapter *adapter)
 {
        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL
@@ -1023,6 +1085,13 @@ static int i2c_imx_probe(struct platform_device *pdev)
                dev_err(&pdev->dev, "can't enable I2C clock\n");
                return ret;
        }
+
+       i2c_imx->pinctrl = devm_pinctrl_get(&pdev->dev);
+       if (IS_ERR(i2c_imx->pinctrl)) {
+               ret = PTR_ERR(i2c_imx->pinctrl);
+               goto clk_disable;
+       }
+
        /* Request IRQ */
        ret = devm_request_irq(&pdev->dev, irq, i2c_imx_isr, 0,
                                pdev->name, i2c_imx);
@@ -1056,6 +1125,8 @@ static int i2c_imx_probe(struct platform_device *pdev)
                goto clk_disable;
        }
 
+       i2c_imx_init_recovery_info(i2c_imx, pdev);
+
        /* Set up platform driver data */
        platform_set_drvdata(pdev, i2c_imx);
        clk_disable_unprepare(i2c_imx->clk);