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// 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);
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