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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 | // SPDX-License-Identifier: GPL-2.0-only /* * w1-gpio - GPIO w1 bus master driver * * Copyright (C) 2007 Ville Syrjala <syrjala@sci.fi> */ #include <linux/delay.h> #include <linux/device.h> #include <linux/err.h> #include <linux/gpio/consumer.h> #include <linux/mod_devicetable.h> #include <linux/module.h> #include <linux/platform_device.h> #include <linux/property.h> #include <linux/types.h> #include <linux/w1.h> struct w1_gpio_ddata { struct gpio_desc *gpiod; struct gpio_desc *pullup_gpiod; unsigned int pullup_duration; }; static u8 w1_gpio_set_pullup(void *data, int delay) { struct w1_gpio_ddata *ddata = data; if (delay) { ddata->pullup_duration = delay; } else { if (ddata->pullup_duration) { /* * This will OVERRIDE open drain emulation and force-pull * the line high for some time. */ gpiod_set_raw_value(ddata->gpiod, 1); msleep(ddata->pullup_duration); /* * This will simply set the line as input since we are doing * open drain emulation in the GPIO library. */ gpiod_set_value(ddata->gpiod, 1); } ddata->pullup_duration = 0; } return 0; } static void w1_gpio_write_bit(void *data, u8 bit) { struct w1_gpio_ddata *ddata = data; gpiod_set_value(ddata->gpiod, bit); } static u8 w1_gpio_read_bit(void *data) { struct w1_gpio_ddata *ddata = data; return gpiod_get_value(ddata->gpiod) ? 1 : 0; } static int w1_gpio_probe(struct platform_device *pdev) { struct w1_bus_master *master; struct w1_gpio_ddata *ddata; struct device *dev = &pdev->dev; /* Enforce open drain mode by default */ enum gpiod_flags gflags = GPIOD_OUT_LOW_OPEN_DRAIN; int err; ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL); if (!ddata) 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 (device_property_present(dev, "linux,open-drain")) gflags = GPIOD_OUT_LOW; master = devm_kzalloc(dev, sizeof(*master), GFP_KERNEL); if (!master) return -ENOMEM; ddata->gpiod = devm_gpiod_get_index(dev, NULL, 0, gflags); if (IS_ERR(ddata->gpiod)) return dev_err_probe(dev, PTR_ERR(ddata->gpiod), "gpio_request (pin) failed\n"); ddata->pullup_gpiod = devm_gpiod_get_index_optional(dev, NULL, 1, GPIOD_OUT_LOW); if (IS_ERR(ddata->pullup_gpiod)) return dev_err_probe(dev, PTR_ERR(ddata->pullup_gpiod), "gpio_request (ext_pullup_enable_pin) failed\n"); master->data = ddata; master->read_bit = w1_gpio_read_bit; gpiod_direction_output(ddata->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) return dev_err_probe(dev, err, "w1_add_master device failed\n"); gpiod_set_value(ddata->pullup_gpiod, 1); platform_set_drvdata(pdev, master); return 0; } static void w1_gpio_remove(struct platform_device *pdev) { struct w1_bus_master *master = platform_get_drvdata(pdev); struct w1_gpio_ddata *ddata = master->data; gpiod_set_value(ddata->pullup_gpiod, 0); w1_remove_master_device(master); } static const struct of_device_id w1_gpio_dt_ids[] = { { .compatible = "w1-gpio" }, {} }; MODULE_DEVICE_TABLE(of, w1_gpio_dt_ids); static struct platform_driver w1_gpio_driver = { .driver = { .name = "w1-gpio", .of_match_table = w1_gpio_dt_ids, }, .probe = w1_gpio_probe, .remove_new = 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"); |