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authorDaniel Mack <daniel@caiaq.de>2009-06-18 03:28:15 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-19 00:03:58 +0400
commitc8a06c1ef0bc45915fc45a170c7c60426971304c (patch)
tree9e8f5d3890766bca481c15aac69ef96f52612874
parent9916219579d078c80377dd3988c2cc213536d868 (diff)
downloadlinux-c8a06c1ef0bc45915fc45a170c7c60426971304c.tar.xz
w1-gpio: add external pull-up enable callback
On embedded devices, sleep mode conditions can be tricky to handle, Especially when processors tend to pull-down the w1 bus during sleep. Bus slaves (such as the ds2760) may interpret this as a reason for power-down conditions and entirely switch off the device. This patch adds a callback function pointer to let users switch on and off the external pull-up resistor. This lets the outside world know whether the processor is currently actively driving the bus or not. When this callback is not provided, the code behaviour won't change. Signed-off-by: Daniel Mack <daniel@caiaq.de> Acked-by: Ville Syrjala <syrjala@sci.fi> Acked-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--drivers/w1/masters/w1-gpio.c35
-rw-r--r--include/linux/w1-gpio.h1
2 files changed, 36 insertions, 0 deletions
diff --git a/drivers/w1/masters/w1-gpio.c b/drivers/w1/masters/w1-gpio.c
index a411702413d6..6f8866d6a905 100644
--- a/drivers/w1/masters/w1-gpio.c
+++ b/drivers/w1/masters/w1-gpio.c
@@ -74,6 +74,9 @@ static int __init w1_gpio_probe(struct platform_device *pdev)
if (err)
goto free_gpio;
+ if (pdata->enable_external_pullup)
+ pdata->enable_external_pullup(1);
+
platform_set_drvdata(pdev, master);
return 0;
@@ -91,6 +94,9 @@ static int __exit w1_gpio_remove(struct platform_device *pdev)
struct w1_bus_master *master = platform_get_drvdata(pdev);
struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
+ if (pdata->enable_external_pullup)
+ pdata->enable_external_pullup(0);
+
w1_remove_master_device(master);
gpio_free(pdata->pin);
kfree(master);
@@ -98,12 +104,41 @@ static int __exit w1_gpio_remove(struct platform_device *pdev)
return 0;
}
+#ifdef CONFIG_PM
+
+static int w1_gpio_suspend(struct platform_device *pdev, pm_message_t state)
+{
+ struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
+
+ if (pdata->enable_external_pullup)
+ pdata->enable_external_pullup(0);
+
+ return 0;
+}
+
+static int w1_gpio_resume(struct platform_device *pdev)
+{
+ struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
+
+ if (pdata->enable_external_pullup)
+ pdata->enable_external_pullup(1);
+
+ return 0;
+}
+
+#else
+#define w1_gpio_suspend NULL
+#define w1_gpio_resume NULL
+#endif
+
static struct platform_driver w1_gpio_driver = {
.driver = {
.name = "w1-gpio",
.owner = THIS_MODULE,
},
.remove = __exit_p(w1_gpio_remove),
+ .suspend = w1_gpio_suspend,
+ .resume = w1_gpio_resume,
};
static int __init w1_gpio_init(void)
diff --git a/include/linux/w1-gpio.h b/include/linux/w1-gpio.h
index 9797fec7748a..3adeff82212f 100644
--- a/include/linux/w1-gpio.h
+++ b/include/linux/w1-gpio.h
@@ -18,6 +18,7 @@
struct w1_gpio_platform_data {
unsigned int pin;
unsigned int is_open_drain:1;
+ void (*enable_external_pullup)(int enable);
};
#endif /* _LINUX_W1_GPIO_H */