1 files changed, 109 insertions, 9 deletions

diff --git a/drivers/i2c/i2c-uclass.c b/drivers/i2c/i2c-uclass.c
index 920811a..4ac6ef8 100644
--- a/drivers/i2c/i2c-uclass.c
+++ b/drivers/i2c/i2c-uclass.c
@@ -11,9 +11,19 @@
 #include <malloc.h>
 #include <dm/device-internal.h>
 #include <dm/lists.h>
+#include <dm/pinctrl.h>
+#ifdef CONFIG_DM_GPIO
+#include <asm/gpio.h>
+#endif
 
 #define I2C_MAX_OFFSET_LEN	4
 
+enum {
+	PIN_SDA = 0,
+	PIN_SCL,
+	PIN_COUNT,
+};
+
 /* Useful debugging function */
 void i2c_dump_msgs(struct i2c_msg *msg, int nmsgs)
 {
@@ -445,20 +455,110 @@ int i2c_get_chip_offset_len(struct udevice *dev)
 	return chip->offset_len;
 }
 
+#ifdef CONFIG_DM_GPIO
+static void i2c_gpio_set_pin(struct gpio_desc *pin, int bit)
+{
+	if (bit)
+		dm_gpio_set_dir_flags(pin, GPIOD_IS_IN);
+	else
+		dm_gpio_set_dir_flags(pin, GPIOD_IS_OUT |
+					   GPIOD_ACTIVE_LOW |
+					   GPIOD_IS_OUT_ACTIVE);
+}
+
+static int i2c_gpio_get_pin(struct gpio_desc *pin)
+{
+	return dm_gpio_get_value(pin);
+}
+
+static int i2c_deblock_gpio_loop(struct gpio_desc *sda_pin,
+				 struct gpio_desc *scl_pin)
+{
+	int counter = 9;
+	int ret = 0;
+
+	i2c_gpio_set_pin(sda_pin, 1);
+	i2c_gpio_set_pin(scl_pin, 1);
+	udelay(5);
+
+	/*  Toggle SCL until slave release SDA */
+	while (counter-- >= 0) {
+		i2c_gpio_set_pin(scl_pin, 1);
+		udelay(5);
+		i2c_gpio_set_pin(scl_pin, 0);
+		udelay(5);
+		if (i2c_gpio_get_pin(sda_pin))
+			break;
+	}
+
+	/* Then, send I2C stop */
+	i2c_gpio_set_pin(sda_pin, 0);
+	udelay(5);
+
+	i2c_gpio_set_pin(scl_pin, 1);
+	udelay(5);
+
+	i2c_gpio_set_pin(sda_pin, 1);
+	udelay(5);
+
+	if (!i2c_gpio_get_pin(sda_pin) || !i2c_gpio_get_pin(scl_pin))
+		ret = -EREMOTEIO;
+
+	return ret;
+}
+
+static int i2c_deblock_gpio(struct udevice *bus)
+{
+	struct gpio_desc gpios[PIN_COUNT];
+	int ret, ret0;
+
+	ret = gpio_request_list_by_name(bus, "gpios", gpios,
+					ARRAY_SIZE(gpios), GPIOD_IS_IN);
+	if (ret != ARRAY_SIZE(gpios)) {
+		debug("%s: I2C Node '%s' has no 'gpios' property %s\n",
+		      __func__, dev_read_name(bus), bus->name);
+		if (ret >= 0) {
+			gpio_free_list(bus, gpios, ret);
+			ret = -ENOENT;
+		}
+		goto out;
+	}
+
+	ret = pinctrl_select_state(bus, "gpio");
+	if (ret) {
+		debug("%s: I2C Node '%s' has no 'gpio' pinctrl state. %s\n",
+		      __func__, dev_read_name(bus), bus->name);
+		goto out_no_pinctrl;
+	}
+
+	ret0 = i2c_deblock_gpio_loop(&gpios[PIN_SDA], &gpios[PIN_SCL]);
+
+	ret = pinctrl_select_state(bus, "default");
+	if (ret) {
+		debug("%s: I2C Node '%s' has no 'default' pinctrl state. %s\n",
+		      __func__, dev_read_name(bus), bus->name);
+	}
+
+	ret = !ret ? ret0 : ret;
+
+out_no_pinctrl:
+	gpio_free_list(bus, gpios, ARRAY_SIZE(gpios));
+out:
+	return ret;
+}
+#else
+static int i2c_deblock_gpio(struct udevice *bus)
+{
+	return -ENOSYS;
+}
+#endif // CONFIG_DM_GPIO
+
 int i2c_deblock(struct udevice *bus)
 {
 	struct dm_i2c_ops *ops = i2c_get_ops(bus);
 
-	/*
-	 * We could implement a software deblocking here if we could get
-	 * access to the GPIOs used by I2C, and switch them to GPIO mode
-	 * and then back to I2C. This is somewhat beyond our powers in
-	 * driver model at present, so for now just fail.
-	 *
-	 * See https://patchwork.ozlabs.org/patch/399040/
-	 */
 	if (!ops->deblock)
-		return -ENOSYS;
+		return i2c_deblock_gpio(bus);
 
 	return ops->deblock(bus);
 }