c8a06c1ef0
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>
159 lines
3.2 KiB
C
159 lines
3.2 KiB
C
/*
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* w1-gpio - GPIO w1 bus master driver
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*
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* Copyright (C) 2007 Ville Syrjala <syrjala@sci.fi>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation.
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*/
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include <linux/w1-gpio.h>
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#include "../w1.h"
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#include "../w1_int.h"
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#include <asm/gpio.h>
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static void w1_gpio_write_bit_dir(void *data, u8 bit)
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{
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struct w1_gpio_platform_data *pdata = data;
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if (bit)
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gpio_direction_input(pdata->pin);
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else
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gpio_direction_output(pdata->pin, 0);
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}
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static void w1_gpio_write_bit_val(void *data, u8 bit)
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{
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struct w1_gpio_platform_data *pdata = data;
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gpio_set_value(pdata->pin, bit);
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}
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static u8 w1_gpio_read_bit(void *data)
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{
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struct w1_gpio_platform_data *pdata = data;
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return gpio_get_value(pdata->pin) ? 1 : 0;
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}
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static int __init w1_gpio_probe(struct platform_device *pdev)
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{
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struct w1_bus_master *master;
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struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
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int err;
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if (!pdata)
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return -ENXIO;
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master = kzalloc(sizeof(struct w1_bus_master), GFP_KERNEL);
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if (!master)
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return -ENOMEM;
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err = gpio_request(pdata->pin, "w1");
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if (err)
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goto free_master;
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master->data = pdata;
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master->read_bit = w1_gpio_read_bit;
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if (pdata->is_open_drain) {
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gpio_direction_output(pdata->pin, 1);
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master->write_bit = w1_gpio_write_bit_val;
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} else {
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gpio_direction_input(pdata->pin);
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master->write_bit = w1_gpio_write_bit_dir;
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}
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err = w1_add_master_device(master);
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if (err)
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goto free_gpio;
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if (pdata->enable_external_pullup)
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pdata->enable_external_pullup(1);
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platform_set_drvdata(pdev, master);
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return 0;
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free_gpio:
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gpio_free(pdata->pin);
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free_master:
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kfree(master);
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return err;
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}
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static int __exit w1_gpio_remove(struct platform_device *pdev)
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{
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struct w1_bus_master *master = platform_get_drvdata(pdev);
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struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
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if (pdata->enable_external_pullup)
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pdata->enable_external_pullup(0);
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w1_remove_master_device(master);
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gpio_free(pdata->pin);
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kfree(master);
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return 0;
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}
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#ifdef CONFIG_PM
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static int w1_gpio_suspend(struct platform_device *pdev, pm_message_t state)
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{
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struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
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if (pdata->enable_external_pullup)
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pdata->enable_external_pullup(0);
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return 0;
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}
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static int w1_gpio_resume(struct platform_device *pdev)
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{
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struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
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if (pdata->enable_external_pullup)
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pdata->enable_external_pullup(1);
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return 0;
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}
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#else
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#define w1_gpio_suspend NULL
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#define w1_gpio_resume NULL
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#endif
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static struct platform_driver w1_gpio_driver = {
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.driver = {
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.name = "w1-gpio",
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.owner = THIS_MODULE,
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},
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.remove = __exit_p(w1_gpio_remove),
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.suspend = w1_gpio_suspend,
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.resume = w1_gpio_resume,
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};
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static int __init w1_gpio_init(void)
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{
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return platform_driver_probe(&w1_gpio_driver, w1_gpio_probe);
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}
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static void __exit w1_gpio_exit(void)
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{
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platform_driver_unregister(&w1_gpio_driver);
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}
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module_init(w1_gpio_init);
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module_exit(w1_gpio_exit);
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MODULE_DESCRIPTION("GPIO w1 bus master driver");
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MODULE_AUTHOR("Ville Syrjala <syrjala@sci.fi>");
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MODULE_LICENSE("GPL");
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