1 files changed, 32 insertions, 6 deletions

diff --git a/drivers/i2c/muxes/i2c-mux-gpio.c b/drivers/i2c/muxes/i2c-mux-gpio.c
index 7c23bb51bd33..566a6757a33d 100644
--- a/drivers/i2c/muxes/i2c-mux-gpio.c
+++ b/drivers/i2c/muxes/i2c-mux-gpio.c
@@ -21,6 +21,7 @@ struct gpiomux {
 	struct i2c_adapter *parent;
 	struct i2c_adapter **adap; /* child busses */
 	struct i2c_mux_gpio_platform_data data;
+	unsigned gpio_base;
 };
 
 static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
@@ -28,7 +29,8 @@ static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
 	int i;
 
 	for (i = 0; i < mux->data.n_gpios; i++)
-		gpio_set_value(mux->data.gpios[i], val & (1 << i));
+		gpio_set_value(mux->gpio_base + mux->data.gpios[i],
+			       val & (1 << i));
 }
 
 static int i2c_mux_gpio_select(struct i2c_adapter *adap, void *data, u32 chan)
@@ -49,13 +51,19 @@ static int i2c_mux_gpio_deselect(struct i2c_adapter *adap, void *data, u32 chan)
 	return 0;
 }
 
+static int __devinit match_gpio_chip_by_label(struct gpio_chip *chip,
+					      void *data)
+{
+	return !strcmp(chip->label, data);
+}
+
 static int __devinit i2c_mux_gpio_probe(struct platform_device *pdev)
 {
 	struct gpiomux *mux;
 	struct i2c_mux_gpio_platform_data *pdata;
 	struct i2c_adapter *parent;
 	int (*deselect) (struct i2c_adapter *, void *, u32);
-	unsigned initial_state;
+	unsigned initial_state, gpio_base;
 	int i, ret;
 
 	pdata = pdev->dev.platform_data;
@@ -64,6 +72,23 @@ static int __devinit i2c_mux_gpio_probe(struct platform_device *pdev)
 		return -ENODEV;
 	}
 
+	/*
+	 * If a GPIO chip name is provided, the GPIO pin numbers provided are
+	 * relative to its base GPIO number. Otherwise they are absolute.
+	 */
+	if (pdata->gpio_chip) {
+		struct gpio_chip *gpio;
+
+		gpio = gpiochip_find(pdata->gpio_chip,
+				     match_gpio_chip_by_label);
+		if (!gpio)
+			return -EPROBE_DEFER;
+
+		gpio_base = gpio->base;
+	} else {
+		gpio_base = 0;
+	}
+
 	parent = i2c_get_adapter(pdata->parent);
 	if (!parent) {
 		dev_err(&pdev->dev, "Parent adapter (%d) not found\n",
@@ -79,6 +104,7 @@ static int __devinit i2c_mux_gpio_probe(struct platform_device *pdev)
 
 	mux->parent = parent;
 	mux->data = *pdata;
+	mux->gpio_base = gpio_base;
 	mux->adap = devm_kzalloc(&pdev->dev,
 				 sizeof(*mux->adap) * pdata->n_values,
 				 GFP_KERNEL);
@@ -96,10 +122,10 @@ static int __devinit i2c_mux_gpio_probe(struct platform_device *pdev)
 	}
 
 	for (i = 0; i < pdata->n_gpios; i++) {
-		ret = gpio_request(pdata->gpios[i], "i2c-mux-gpio");
+		ret = gpio_request(gpio_base + pdata->gpios[i], "i2c-mux-gpio");
 		if (ret)
 			goto err_request_gpio;
-		gpio_direction_output(pdata->gpios[i],
+		gpio_direction_output(gpio_base + pdata->gpios[i],
 				      initial_state & (1 << i));
 	}
 
@@ -130,7 +156,7 @@ add_adapter_failed:
 	i = pdata->n_gpios;
 err_request_gpio:
 	for (; i > 0; i--)
-		gpio_free(pdata->gpios[i - 1]);
+		gpio_free(gpio_base + pdata->gpios[i - 1]);
 alloc_failed:
 	i2c_put_adapter(parent);
 
@@ -146,7 +172,7 @@ static int __devexit i2c_mux_gpio_remove(struct platform_device *pdev)
 		i2c_del_mux_adapter(mux->adap[i]);
 
 	for (i = 0; i < mux->data.n_gpios; i++)
-		gpio_free(mux->data.gpios[i]);
+		gpio_free(mux->gpio_base + mux->data.gpios[i]);
 
 	platform_set_drvdata(pdev, NULL);
 	i2c_put_adapter(mux->parent);