Loading...
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 | // SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2015-2017 Pengutronix, Uwe Kleine-König <kernel@pengutronix.de> */ #include <linux/gpio/consumer.h> #include <linux/module.h> #include <linux/mod_devicetable.h> #include <linux/platform_device.h> #include <linux/delay.h> #include "siox.h" #define DRIVER_NAME "siox-gpio" struct siox_gpio_ddata { struct gpio_desc *din; struct gpio_desc *dout; struct gpio_desc *dclk; struct gpio_desc *dld; }; static unsigned int siox_clkhigh_ns = 1000; static unsigned int siox_loadhigh_ns; static unsigned int siox_bytegap_ns; static int siox_gpio_pushpull(struct siox_master *smaster, size_t setbuf_len, const u8 setbuf[], size_t getbuf_len, u8 getbuf[]) { struct siox_gpio_ddata *ddata = siox_master_get_devdata(smaster); size_t i; size_t cycles = max(setbuf_len, getbuf_len); /* reset data and clock */ gpiod_set_value_cansleep(ddata->dout, 0); gpiod_set_value_cansleep(ddata->dclk, 0); gpiod_set_value_cansleep(ddata->dld, 1); ndelay(siox_loadhigh_ns); gpiod_set_value_cansleep(ddata->dld, 0); for (i = 0; i < cycles; ++i) { u8 set = 0, get = 0; size_t j; if (i >= cycles - setbuf_len) set = setbuf[i - (cycles - setbuf_len)]; for (j = 0; j < 8; ++j) { get <<= 1; if (gpiod_get_value_cansleep(ddata->din)) get |= 1; /* DOUT is logically inverted */ gpiod_set_value_cansleep(ddata->dout, !(set & 0x80)); set <<= 1; gpiod_set_value_cansleep(ddata->dclk, 1); ndelay(siox_clkhigh_ns); gpiod_set_value_cansleep(ddata->dclk, 0); } if (i < getbuf_len) getbuf[i] = get; ndelay(siox_bytegap_ns); } gpiod_set_value_cansleep(ddata->dld, 1); ndelay(siox_loadhigh_ns); gpiod_set_value_cansleep(ddata->dld, 0); /* * Resetting dout isn't necessary protocol wise, but it makes the * signals more pretty because the dout level is deterministic between * cycles. Note that this only affects dout between the master and the * first siox device. dout for the later devices depend on the output of * the previous siox device. */ gpiod_set_value_cansleep(ddata->dout, 0); return 0; } static int siox_gpio_probe(struct platform_device *pdev) { struct device *dev = &pdev->dev; struct siox_gpio_ddata *ddata; int ret; struct siox_master *smaster; smaster = siox_master_alloc(&pdev->dev, sizeof(*ddata)); if (!smaster) { dev_err(dev, "failed to allocate siox master\n"); return -ENOMEM; } platform_set_drvdata(pdev, smaster); ddata = siox_master_get_devdata(smaster); ddata->din = devm_gpiod_get(dev, "din", GPIOD_IN); if (IS_ERR(ddata->din)) { ret = PTR_ERR(ddata->din); dev_err(dev, "Failed to get %s GPIO: %d\n", "din", ret); goto err; } ddata->dout = devm_gpiod_get(dev, "dout", GPIOD_OUT_LOW); if (IS_ERR(ddata->dout)) { ret = PTR_ERR(ddata->dout); dev_err(dev, "Failed to get %s GPIO: %d\n", "dout", ret); goto err; } ddata->dclk = devm_gpiod_get(dev, "dclk", GPIOD_OUT_LOW); if (IS_ERR(ddata->dclk)) { ret = PTR_ERR(ddata->dclk); dev_err(dev, "Failed to get %s GPIO: %d\n", "dclk", ret); goto err; } ddata->dld = devm_gpiod_get(dev, "dld", GPIOD_OUT_LOW); if (IS_ERR(ddata->dld)) { ret = PTR_ERR(ddata->dld); dev_err(dev, "Failed to get %s GPIO: %d\n", "dld", ret); goto err; } smaster->pushpull = siox_gpio_pushpull; /* XXX: determine automatically like spi does */ smaster->busno = 0; ret = siox_master_register(smaster); if (ret) { dev_err(dev, "Failed to register siox master: %d\n", ret); err: siox_master_put(smaster); } return ret; } static int siox_gpio_remove(struct platform_device *pdev) { struct siox_master *master = platform_get_drvdata(pdev); siox_master_unregister(master); return 0; } static const struct of_device_id siox_gpio_dt_ids[] = { { .compatible = "eckelmann,siox-gpio", }, { /* sentinel */ } }; MODULE_DEVICE_TABLE(of, siox_gpio_dt_ids); static struct platform_driver siox_gpio_driver = { .probe = siox_gpio_probe, .remove = siox_gpio_remove, .driver = { .name = DRIVER_NAME, .of_match_table = siox_gpio_dt_ids, }, }; module_platform_driver(siox_gpio_driver); MODULE_AUTHOR("Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>"); MODULE_LICENSE("GPL v2"); MODULE_ALIAS("platform:" DRIVER_NAME); |