From c8a06c1ef0bc45915fc45a170c7c60426971304c Mon Sep 17 00:00:00 2001 From: Daniel Mack Date: Wed, 17 Jun 2009 16:28:15 -0700 Subject: 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 Acked-by: Ville Syrjala Acked-by: Evgeniy Polyakov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/w1/masters/w1-gpio.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) (limited to 'drivers/w1') 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) -- cgit v1.2.3