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

[Clark Wang]

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@xxxxxxx>
---
V2 changes:
 - No change. Add dt-bindings in the next patch.
---
 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