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