lkml.org 
[lkml]   [2009]   [May]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] w1-gpio: add external pull-up enable callback
Date
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>
Cc: Ville Syrjala <syrjala@sci.fi>
---
drivers/w1/masters/w1-gpio.c | 35 +++++++++++++++++++++++++++++++++++
include/linux/w1-gpio.h | 1 +
2 files changed, 36 insertions(+), 0 deletions(-)

diff --git a/drivers/w1/masters/w1-gpio.c b/drivers/w1/masters/w1-gpio.c
index a411702..6f8866d 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 9797fec..3adeff8 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 */
--
1.6.2.1


\
 
 \ /
  Last update: 2009-05-05 15:13    [W:1.103 / U:1.556 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site