1 // SPDX-License-Identifier: GPL-2.0-only
3  * w1-gpio - GPIO w1 bus master driver
8 #include <linux/delay.h>
26 static u8 w1_gpio_set_pullup(void *data, int delay)  in w1_gpio_set_pullup()  argument
30 	if (delay) {  in w1_gpio_set_pullup()
31 		ddata->pullup_duration = delay;  in w1_gpio_set_pullup()
33 		if (ddata->pullup_duration) {  in w1_gpio_set_pullup()
35 			 * This will OVERRIDE open drain emulation and force-pull  in w1_gpio_set_pullup()
36 			 * the line high for some time.  in w1_gpio_set_pullup()
38 			gpiod_set_raw_value(ddata->gpiod, 1);  in w1_gpio_set_pullup()
39 			msleep(ddata->pullup_duration);  in w1_gpio_set_pullup()
41 			 * This will simply set the line as input since we are doing  in w1_gpio_set_pullup()
44 			gpiod_set_value(ddata->gpiod, 1);  in w1_gpio_set_pullup()
46 		ddata->pullup_duration = 0;  in w1_gpio_set_pullup()
56 	gpiod_set_value(ddata->gpiod, bit);  in w1_gpio_write_bit()
63 	return gpiod_get_value(ddata->gpiod) ? 1 : 0;  in w1_gpio_read_bit()
70 	struct device *dev = &pdev->dev;  in w1_gpio_probe()
75 	ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);  in w1_gpio_probe()
77 		return -ENOMEM;  in w1_gpio_probe()
81 	 * already set the line into open drain mode, so we should just  in w1_gpio_probe()
82 	 * driver it high/low like we are in full control of the line and  in w1_gpio_probe()
85 	if (device_property_present(dev, "linux,open-drain"))  in w1_gpio_probe()
90 		return -ENOMEM;  in w1_gpio_probe()
92 	ddata->gpiod = devm_gpiod_get_index(dev, NULL, 0, gflags);  in w1_gpio_probe()
93 	if (IS_ERR(ddata->gpiod))  in w1_gpio_probe()
94 		return dev_err_probe(dev, PTR_ERR(ddata->gpiod), "gpio_request (pin) failed\n");  in w1_gpio_probe()
96 	ddata->pullup_gpiod =  in w1_gpio_probe()
98 	if (IS_ERR(ddata->pullup_gpiod))  in w1_gpio_probe()
99 		return dev_err_probe(dev, PTR_ERR(ddata->pullup_gpiod),  in w1_gpio_probe()
102 	master->data = ddata;  in w1_gpio_probe()
103 	master->read_bit = w1_gpio_read_bit;  in w1_gpio_probe()
104 	gpiod_direction_output(ddata->gpiod, 1);  in w1_gpio_probe()
105 	master->write_bit = w1_gpio_write_bit;  in w1_gpio_probe()
109 	 * we need to use this pullup function that hammers the line  in w1_gpio_probe()
110 	 * high using a raw accessor to provide pull-up for the w1  in w1_gpio_probe()
111 	 * line.  in w1_gpio_probe()
114 		master->set_pullup = w1_gpio_set_pullup;  in w1_gpio_probe()
120 	gpiod_set_value(ddata->pullup_gpiod, 1);  in w1_gpio_probe()
130 	struct w1_gpio_ddata *ddata = master->data;  in w1_gpio_remove()
132 	gpiod_set_value(ddata->pullup_gpiod, 0);  in w1_gpio_remove()
138 	{ .compatible = "w1-gpio" },
145 		.name	= "w1-gpio",