onewire: w1-gpio: add ext_pullup_enable pin in platform data

In the process of porting boards to devicetree implemenation, we should
keep information about external circuitry where they belong - the
individual drivers.

This patch adds a way to specify a GPIO to drive the (optional) external
pull-up logic, rather than using a function pointer for that.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Acked-by: Ville Syrjälä <syrjala@sci.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/w1/masters/w1-gpio.c

@@ -104,6 +104,13 @@ static int __init w1_gpio_probe(struct platform_device *pdev)
 	if (err)
 		goto free_master;
 
+	if (gpio_is_valid(pdata->ext_pullup_enable_pin)) {
+		err = gpio_request_one(pdata->ext_pullup_enable_pin,
+				       GPIOF_INIT_LOW, "w1 pullup");
+		if (err < 0)
+			goto free_gpio;
+	}
+
 	master->data = pdata;
 	master->read_bit = w1_gpio_read_bit;
 
@@ -117,15 +124,21 @@ static int __init w1_gpio_probe(struct platform_device *pdev)
 
 	err = w1_add_master_device(master);
 	if (err)
-		goto free_gpio;
+		goto free_gpio_ext_pu;
 
 	if (pdata->enable_external_pullup)
 		pdata->enable_external_pullup(1);
 
+	if (gpio_is_valid(pdata->ext_pullup_enable_pin))
+		gpio_set_value(pdata->ext_pullup_enable_pin, 1);
+
 	platform_set_drvdata(pdev, master);
 
 	return 0;
 
+ free_gpio_ext_pu:
+	if (gpio_is_valid(pdata->ext_pullup_enable_pin))
+		gpio_free(pdata->ext_pullup_enable_pin);
  free_gpio:
 	gpio_free(pdata->pin);
  free_master:
@@ -142,6 +155,9 @@ static int __exit w1_gpio_remove(struct platform_device *pdev)
 	if (pdata->enable_external_pullup)
 		pdata->enable_external_pullup(0);
 
+	if (gpio_is_valid(pdata->ext_pullup_enable_pin))
+		gpio_set_value(pdata->ext_pullup_enable_pin, 0);
+
 	w1_remove_master_device(master);
 	gpio_free(pdata->pin);
 	kfree(master);

include/linux/w1-gpio.h

@@ -19,6 +19,7 @@ struct w1_gpio_platform_data {
 	unsigned int pin;
 	unsigned int is_open_drain:1;
 	void (*enable_external_pullup)(int enable);
+	unsigned int ext_pullup_enable_pin;
 };
 
 #endif /* _LINUX_W1_GPIO_H */