[PATCH 05/12] i2c: pxa: Add bus reset functionality

[Vaibhav Hiremath]

From: Rob Herring <robh at kernel.org>

Since there is some problematic i2c slave devices on some
platforms such as dkb (sometimes), it will drop down sda
and make i2c bus hang, at that time, it need to config
scl/sda into gpio to simulate "stop" sequence to recover
i2c bus, so add this interface.

Signed-off-by: Leilei Shang <shangll at marvell.com>
Signed-off-by: Rob Herring <robh at kernel.org>
[vaibhav.hiremath at linaro.org: Updated Changelog]
Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath at linaro.org>

Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath at linaro.org>
---
 drivers/i2c/busses/i2c-pxa.c | 90 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)

diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
index 8ca5552..eb09071 100644
--- a/drivers/i2c/busses/i2c-pxa.c
+++ b/drivers/i2c/busses/i2c-pxa.c
@@ -37,6 +37,8 @@
 #include <linux/slab.h>
 #include <linux/io.h>
 #include <linux/i2c/pxa-i2c.h>
+#include <linux/of_gpio.h>
+#include <linux/pinctrl/consumer.h>
 
 #include <asm/irq.h>
 
@@ -177,6 +179,9 @@ struct pxa_i2c {
 	bool			highmode_enter;
 	unsigned int		ilcr;
 	unsigned int		iwcr;
+	struct pinctrl		*pinctrl;
+	struct pinctrl_state	*pin_i2c;
+	struct pinctrl_state	*pin_gpio;
 };
 
 #define _IBMR(i2c)	((i2c)->reg_ibmr)
@@ -269,6 +274,62 @@ static void i2c_pxa_show_state(struct pxa_i2c *i2c, int lno, const char *fname)
 
 #define show_state(i2c) i2c_pxa_show_state(i2c, __LINE__, __func__)
 
+static void i2c_bus_reset(struct pxa_i2c *i2c)
+{
+	int ret, ccnt, pins_scl, pins_sda;
+	struct device *dev = i2c->adap.dev.parent;
+	struct device_node *np = dev->of_node;
+
+	if (!i2c->pinctrl) {
+		dev_warn(dev, "could not do i2c bus reset\n");
+		return;
+	}
+
+	ret = pinctrl_select_state(i2c->pinctrl, i2c->pin_gpio);
+	if (ret) {
+		dev_err(dev, "could not set gpio pins\n");
+		return;
+	}
+
+	pins_scl = of_get_named_gpio(np, "i2c-gpio", 0);
+	if (!gpio_is_valid(pins_scl)) {
+		dev_err(dev, "i2c scl gpio not set\n");
+		goto err_out;
+	}
+	pins_sda = of_get_named_gpio(np, "i2c-gpio", 1);
+	if (!gpio_is_valid(pins_sda)) {
+		dev_err(dev, "i2c sda gpio not set\n");
+		goto err_out;
+	}
+
+	gpio_request(pins_scl, NULL);
+	gpio_request(pins_sda, NULL);
+
+	gpio_direction_input(pins_sda);
+	for (ccnt = 20; ccnt; ccnt--) {
+		gpio_direction_output(pins_scl, ccnt & 0x01);
+		udelay(5);
+	}
+	gpio_direction_output(pins_scl, 0);
+	udelay(5);
+	gpio_direction_output(pins_sda, 0);
+	udelay(5);
+	/* stop signal */
+	gpio_direction_output(pins_scl, 1);
+	udelay(5);
+	gpio_direction_output(pins_sda, 1);
+	udelay(5);
+
+	gpio_free(pins_scl);
+	gpio_free(pins_sda);
+
+err_out:
+	ret = pinctrl_select_state(i2c->pinctrl, i2c->pin_i2c);
+	if (ret)
+		dev_err(dev, "could not set default(i2c) pins\n");
+	return;
+}
+
 static void i2c_pxa_scream_blue_murder(struct pxa_i2c *i2c, const char *why)
 {
 	unsigned int i;
@@ -281,6 +342,11 @@ static void i2c_pxa_scream_blue_murder(struct pxa_i2c *i2c, const char *why)
 	for (i = 0; i < i2c->irqlogidx; i++)
 		printk("[%08x:%08x] ", i2c->isrlog[i], i2c->icrlog[i]);
 	printk("\n");
+	if (strcmp(why, "exhausted retries") != 0) {
+		i2c_bus_reset(i2c);
+		/* reset i2c contorler when it's fail */
+		i2c_pxa_reset(i2c);
+	}
 }
 
 #else /* ifdef DEBUG */
@@ -1301,6 +1367,30 @@ static int i2c_pxa_probe(struct platform_device *dev)
 
 	platform_set_drvdata(dev, i2c);
 
+	i2c->pinctrl = devm_pinctrl_get(&dev->dev);
+	if (IS_ERR(i2c->pinctrl)) {
+		i2c->pinctrl = NULL;
+		dev_warn(&dev->dev, "could not get pinctrl\n");
+	} else {
+		i2c->pin_i2c = pinctrl_lookup_state(i2c->pinctrl, "default");
+		if (IS_ERR(i2c->pin_i2c)) {
+			dev_err(&dev->dev, "could not get default(i2c) pinstate\n");
+			ret = IS_ERR(i2c->pin_i2c);
+		}
+
+		i2c->pin_gpio = pinctrl_lookup_state(i2c->pinctrl, "gpio");
+		if (IS_ERR(i2c->pin_gpio)) {
+			dev_err(&dev->dev, "could not get gpio pinstate\n");
+			ret = IS_ERR(i2c->pin_gpio);
+		}
+
+		if (ret) {
+			i2c->pin_i2c = NULL;
+			i2c->pin_gpio = NULL;
+			i2c->pinctrl = NULL;
+			ret = 0;
+		}
+	}
 #ifdef CONFIG_I2C_PXA_SLAVE
 	printk(KERN_INFO "I2C: %s: PXA I2C adapter, slave address %d\n",
 	       dev_name(&i2c->adap.dev), i2c->slave_addr);
-- 
1.9.1