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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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 | /* SPDX-License-Identifier: GPL-2.0+ * * Copyright (c) 2015 Free Electrons * Copyright (c) 2015 NextThing Co * * Maxime Ripard <maxime.ripard@free-electrons.com> * */ #include <dm.h> #include <log.h> #include <w1.h> #include <linux/delay.h> #include <asm/gpio.h> #define W1_TIMING_A 6 #define W1_TIMING_B 64 #define W1_TIMING_C 60 #define W1_TIMING_D 10 #define W1_TIMING_E 9 #define W1_TIMING_F 55 #define W1_TIMING_G 0 #define W1_TIMING_H 480 #define W1_TIMING_I 70 #define W1_TIMING_J 410 struct w1_gpio_pdata { struct gpio_desc gpio; u64 search_id; }; static bool w1_gpio_read_bit(struct udevice *dev) { struct w1_gpio_pdata *pdata = dev_get_plat(dev); int val; dm_gpio_set_dir_flags(&pdata->gpio, GPIOD_IS_OUT); udelay(W1_TIMING_A); dm_gpio_set_dir_flags(&pdata->gpio, GPIOD_IS_IN); udelay(W1_TIMING_E); val = dm_gpio_get_value(&pdata->gpio); if (val < 0) debug("error in retrieving GPIO value"); udelay(W1_TIMING_F); return val; } static u8 w1_gpio_read_byte(struct udevice *dev) { int i; u8 ret = 0; for (i = 0; i < 8; ++i) ret |= (w1_gpio_read_bit(dev) ? 1 : 0) << i; return ret; } static void w1_gpio_write_bit(struct udevice *dev, bool bit) { struct w1_gpio_pdata *pdata = dev_get_plat(dev); dm_gpio_set_dir_flags(&pdata->gpio, GPIOD_IS_OUT); bit ? udelay(W1_TIMING_A) : udelay(W1_TIMING_C); dm_gpio_set_value(&pdata->gpio, 1); bit ? udelay(W1_TIMING_B) : udelay(W1_TIMING_D); } static void w1_gpio_write_byte(struct udevice *dev, u8 byte) { int i; for (i = 0; i < 8; ++i) w1_gpio_write_bit(dev, (byte >> i) & 0x1); } static bool w1_gpio_reset(struct udevice *dev) { struct w1_gpio_pdata *pdata = dev_get_plat(dev); int val; /* initiate the reset pulse. first we must pull the bus to low */ dm_gpio_set_dir_flags(&pdata->gpio, GPIOD_IS_OUT | GPIOD_IS_OUT_ACTIVE); udelay(W1_TIMING_G); dm_gpio_set_value(&pdata->gpio, 0); /* wait for the specified time with the bus kept low */ udelay(W1_TIMING_H); /* now we must read the presence pulse */ dm_gpio_set_dir_flags(&pdata->gpio, GPIOD_IS_IN); udelay(W1_TIMING_I); val = dm_gpio_get_value(&pdata->gpio); if (val < 0) debug("error in retrieving GPIO value"); /* if nobody pulled the bus down , it means nobody is on the bus */ if (val != 0) return 1; /* we have the bus pulled down, let's wait for the specified presence time */ udelay(W1_TIMING_J); /* read again, the other end should leave the bus free */ val = dm_gpio_get_value(&pdata->gpio); if (val < 0) debug("error in retrieving GPIO value"); /* bus is not going up again, so we have an error */ if (val != 1) return 1; /* all good, presence detected */ return 0; } static u8 w1_gpio_triplet(struct udevice *dev, bool bdir) { u8 id_bit = w1_gpio_read_bit(dev); u8 comp_bit = w1_gpio_read_bit(dev); u8 retval; if (id_bit && comp_bit) return 0x03; /* error */ if (!id_bit && !comp_bit) { /* Both bits are valid, take the direction given */ retval = bdir ? 0x04 : 0; } else { /* Only one bit is valid, take that direction */ bdir = id_bit; retval = id_bit ? 0x05 : 0x02; } w1_gpio_write_bit(dev, bdir); return retval; } static const struct w1_ops w1_gpio_ops = { .read_byte = w1_gpio_read_byte, .reset = w1_gpio_reset, .triplet = w1_gpio_triplet, .write_byte = w1_gpio_write_byte, }; static int w1_gpio_of_to_plat(struct udevice *dev) { struct w1_gpio_pdata *pdata = dev_get_plat(dev); int ret; ret = gpio_request_by_name(dev, "gpios", 0, &pdata->gpio, GPIOD_IS_IN); if (ret < 0) printf("Error claiming GPIO %d\n", ret); return ret; }; static const struct udevice_id w1_gpio_id[] = { { "w1-gpio", 0 }, { }, }; U_BOOT_DRIVER(w1_gpio_drv) = { .id = UCLASS_W1, .name = "w1_gpio_drv", .of_match = w1_gpio_id, .of_to_plat = w1_gpio_of_to_plat, .ops = &w1_gpio_ops, .plat_auto = sizeof(struct w1_gpio_pdata), }; |