// 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/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);