diff options
Diffstat (limited to 'drivers/w1/masters/w1-gpio.c')
| -rw-r--r-- | drivers/w1/masters/w1-gpio.c | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/drivers/w1/masters/w1-gpio.c b/drivers/w1/masters/w1-gpio.c new file mode 100644 index 000000000..d4632aace --- /dev/null +++ b/drivers/w1/masters/w1-gpio.c @@ -0,0 +1,206 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * w1-gpio - GPIO w1 bus master driver + * + * Copyright (C) 2007 Ville Syrjala <syrjala@sci.fi> + */ + +#include <linux/init.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/slab.h> +#include <linux/w1-gpio.h> +#include <linux/gpio/consumer.h> +#include <linux/of_platform.h> +#include <linux/err.h> +#include <linux/of.h> +#include <linux/delay.h> + +#include <linux/w1.h> + +static u8 w1_gpio_set_pullup(void *data, int delay) +{ + struct w1_gpio_platform_data *pdata = data; + + if (delay) { + pdata->pullup_duration = delay; + } else { + if (pdata->pullup_duration) { + /* + * This will OVERRIDE open drain emulation and force-pull + * the line high for some time. + */ + gpiod_set_raw_value(pdata->gpiod, 1); + msleep(pdata->pullup_duration); + /* + * This will simply set the line as input since we are doing + * open drain emulation in the GPIO library. + */ + gpiod_set_value(pdata->gpiod, 1); + } + pdata->pullup_duration = 0; + } + + return 0; +} + +static void w1_gpio_write_bit(void *data, u8 bit) +{ + struct w1_gpio_platform_data *pdata = data; + + gpiod_set_value(pdata->gpiod, bit); +} + +static u8 w1_gpio_read_bit(void *data) +{ + struct w1_gpio_platform_data *pdata = data; + + return gpiod_get_value(pdata->gpiod) ? 1 : 0; +} + +#if defined(CONFIG_OF) +static const struct of_device_id w1_gpio_dt_ids[] = { + { .compatible = "w1-gpio" }, + {} +}; +MODULE_DEVICE_TABLE(of, w1_gpio_dt_ids); +#endif + +static int w1_gpio_probe(struct platform_device *pdev) +{ + struct w1_bus_master *master; + struct w1_gpio_platform_data *pdata; + struct device *dev = &pdev->dev; + struct device_node *np = dev->of_node; + /* Enforce open drain mode by default */ + enum gpiod_flags gflags = GPIOD_OUT_LOW_OPEN_DRAIN; + int err; + + if (of_have_populated_dt()) { + pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL); + if (!pdata) + return -ENOMEM; + + /* + * This parameter means that something else than the gpiolib has + * already set the line into open drain mode, so we should just + * driver it high/low like we are in full control of the line and + * open drain will happen transparently. + */ + if (of_get_property(np, "linux,open-drain", NULL)) + gflags = GPIOD_OUT_LOW; + + pdev->dev.platform_data = pdata; + } + pdata = dev_get_platdata(dev); + + if (!pdata) { + dev_err(dev, "No configuration data\n"); + return -ENXIO; + } + + master = devm_kzalloc(dev, sizeof(struct w1_bus_master), + GFP_KERNEL); + if (!master) { + dev_err(dev, "Out of memory\n"); + return -ENOMEM; + } + + pdata->gpiod = devm_gpiod_get_index(dev, NULL, 0, gflags); + if (IS_ERR(pdata->gpiod)) { + dev_err(dev, "gpio_request (pin) failed\n"); + return PTR_ERR(pdata->gpiod); + } + + pdata->pullup_gpiod = + devm_gpiod_get_index_optional(dev, NULL, 1, GPIOD_OUT_LOW); + if (IS_ERR(pdata->pullup_gpiod)) { + dev_err(dev, "gpio_request_one " + "(ext_pullup_enable_pin) failed\n"); + return PTR_ERR(pdata->pullup_gpiod); + } + + master->data = pdata; + master->read_bit = w1_gpio_read_bit; + gpiod_direction_output(pdata->gpiod, 1); + master->write_bit = w1_gpio_write_bit; + + /* + * If we are using open drain emulation from the GPIO library, + * we need to use this pullup function that hammers the line + * high using a raw accessor to provide pull-up for the w1 + * line. + */ + if (gflags == GPIOD_OUT_LOW_OPEN_DRAIN) + master->set_pullup = w1_gpio_set_pullup; + + err = w1_add_master_device(master); + if (err) { + dev_err(dev, "w1_add_master device failed\n"); + return err; + } + + if (pdata->enable_external_pullup) + pdata->enable_external_pullup(1); + + if (pdata->pullup_gpiod) + gpiod_set_value(pdata->pullup_gpiod, 1); + + platform_set_drvdata(pdev, master); + + return 0; +} + +static int w1_gpio_remove(struct platform_device *pdev) +{ + struct w1_bus_master *master = platform_get_drvdata(pdev); + struct w1_gpio_platform_data *pdata = dev_get_platdata(&pdev->dev); + + if (pdata->enable_external_pullup) + pdata->enable_external_pullup(0); + + if (pdata->pullup_gpiod) + gpiod_set_value(pdata->pullup_gpiod, 0); + + w1_remove_master_device(master); + + return 0; +} + +static int __maybe_unused w1_gpio_suspend(struct device *dev) +{ + struct w1_gpio_platform_data *pdata = dev_get_platdata(dev); + + if (pdata->enable_external_pullup) + pdata->enable_external_pullup(0); + + return 0; +} + +static int __maybe_unused w1_gpio_resume(struct device *dev) +{ + struct w1_gpio_platform_data *pdata = dev_get_platdata(dev); + + if (pdata->enable_external_pullup) + pdata->enable_external_pullup(1); + + return 0; +} + +static SIMPLE_DEV_PM_OPS(w1_gpio_pm_ops, w1_gpio_suspend, w1_gpio_resume); + +static struct platform_driver w1_gpio_driver = { + .driver = { + .name = "w1-gpio", + .pm = &w1_gpio_pm_ops, + .of_match_table = of_match_ptr(w1_gpio_dt_ids), + }, + .probe = w1_gpio_probe, + .remove = w1_gpio_remove, +}; + +module_platform_driver(w1_gpio_driver); + +MODULE_DESCRIPTION("GPIO w1 bus master driver"); +MODULE_AUTHOR("Ville Syrjala <syrjala@sci.fi>"); +MODULE_LICENSE("GPL"); |