1 // SPDX-License-Identifier: GPL-2.0-only
3  * NBUS driver for TS-4600 based boards
5  * Copyright (c) 2016 - Savoir-faire Linux
8  * This driver implements a GPIOs bit-banged bus, called the NBUS by Technologic
10  * TS-4600 SoM.
21 #include <linux/ts-nbus.h>
33 	struct gpio_desc *strobe;  member
40  * request all gpios required by the bus.
45 	ts_nbus->data = devm_gpiod_get_array(&pdev->dev, "ts,data",  in ts_nbus_init_pdata()
47 	if (IS_ERR(ts_nbus->data))  in ts_nbus_init_pdata()
48 		return dev_err_probe(&pdev->dev, PTR_ERR(ts_nbus->data),  in ts_nbus_init_pdata()
49 				     "failed to retrieve ts,data-gpio from dts\n");  in ts_nbus_init_pdata()
51 	ts_nbus->csn = devm_gpiod_get(&pdev->dev, "ts,csn", GPIOD_OUT_HIGH);  in ts_nbus_init_pdata()
52 	if (IS_ERR(ts_nbus->csn))  in ts_nbus_init_pdata()
53 		return dev_err_probe(&pdev->dev, PTR_ERR(ts_nbus->csn),  in ts_nbus_init_pdata()
54 			      "failed to retrieve ts,csn-gpio from dts\n");  in ts_nbus_init_pdata()
56 	ts_nbus->txrx = devm_gpiod_get(&pdev->dev, "ts,txrx", GPIOD_OUT_HIGH);  in ts_nbus_init_pdata()
57 	if (IS_ERR(ts_nbus->txrx))  in ts_nbus_init_pdata()
58 		return dev_err_probe(&pdev->dev, PTR_ERR(ts_nbus->txrx),  in ts_nbus_init_pdata()
59 				     "failed to retrieve ts,txrx-gpio from dts\n");  in ts_nbus_init_pdata()
61 	ts_nbus->strobe = devm_gpiod_get(&pdev->dev, "ts,strobe", GPIOD_OUT_HIGH);  in ts_nbus_init_pdata()
62 	if (IS_ERR(ts_nbus->strobe))  in ts_nbus_init_pdata()
63 		return dev_err_probe(&pdev->dev, PTR_ERR(ts_nbus->strobe),  in ts_nbus_init_pdata()
64 				     "failed to retrieve ts,strobe-gpio from dts\n");  in ts_nbus_init_pdata()
66 	ts_nbus->ale = devm_gpiod_get(&pdev->dev, "ts,ale", GPIOD_OUT_HIGH);  in ts_nbus_init_pdata()
67 	if (IS_ERR(ts_nbus->ale))  in ts_nbus_init_pdata()
68 		return dev_err_probe(&pdev->dev, PTR_ERR(ts_nbus->ale),  in ts_nbus_init_pdata()
69 				     "failed to retrieve ts,ale-gpio from dts\n");  in ts_nbus_init_pdata()
71 	ts_nbus->rdy = devm_gpiod_get(&pdev->dev, "ts,rdy", GPIOD_IN);  in ts_nbus_init_pdata()
72 	if (IS_ERR(ts_nbus->rdy))  in ts_nbus_init_pdata()
73 		return dev_err_probe(&pdev->dev, PTR_ERR(ts_nbus->rdy),  in ts_nbus_init_pdata()
74 				     "failed to retrieve ts,rdy-gpio from dts\n");  in ts_nbus_init_pdata()
80  * the data gpios are used for reading and writing values, their directions
89 			gpiod_direction_input(ts_nbus->data->desc[i]);  in ts_nbus_set_direction()
93 			gpiod_direction_output(ts_nbus->data->desc[i], 1);  in ts_nbus_set_direction()
99  * The data, csn, strobe and ale lines must be zero'ed to let the FPGA knows a
108 	gpiod_set_array_value_cansleep(8, ts_nbus->data->desc,  in ts_nbus_reset_bus()
109 				       ts_nbus->data->info, values);  in ts_nbus_reset_bus()
110 	gpiod_set_value_cansleep(ts_nbus->csn, 0);  in ts_nbus_reset_bus()
111 	gpiod_set_value_cansleep(ts_nbus->strobe, 0);  in ts_nbus_reset_bus()
112 	gpiod_set_value_cansleep(ts_nbus->ale, 0);  in ts_nbus_reset_bus()
120 	gpiod_set_value_cansleep(ts_nbus->strobe, 1);  in ts_nbus_start_transaction()
124  * read a byte value from the data gpios.
129 	struct gpio_descs *gpios = ts_nbus->data;  in ts_nbus_read_byte()  local
134 		ret = gpiod_get_value_cansleep(gpios->desc[i]);  in ts_nbus_read_byte()
145  * set the data gpios accordingly to the byte value.
149 	struct gpio_descs *gpios = ts_nbus->data;  in ts_nbus_write_byte()  local
154 	gpiod_set_array_value_cansleep(8, gpios->desc, gpios->info, values);  in ts_nbus_write_byte()
159  * send the data in the data gpios and return the read value.
173  * value in the data gpios.
180 		gpiod_set_value_cansleep(ts_nbus->ale, 1);  in ts_nbus_write_bus()
196 	mutex_lock(&ts_nbus->lock);  in ts_nbus_read()
199 	gpiod_set_value_cansleep(ts_nbus->txrx, 0);  in ts_nbus_read()
204 	/* set the data gpios direction as input before reading */  in ts_nbus_read()
211 		for (i = 1; i >= 0; i--) {  in ts_nbus_read()
220 		gpiod_set_value_cansleep(ts_nbus->csn, 1);  in ts_nbus_read()
221 		ret = gpiod_get_value_cansleep(ts_nbus->rdy);  in ts_nbus_read()
225 	/* restore the data gpios direction as output after reading */  in ts_nbus_read()
228 	mutex_unlock(&ts_nbus->lock);  in ts_nbus_read()
242 	mutex_lock(&ts_nbus->lock);  in ts_nbus_write()
245 	gpiod_set_value_cansleep(ts_nbus->txrx, 1);  in ts_nbus_write()
251 	for (i = 1; i >= 0; i--)  in ts_nbus_write()
255 	gpiod_set_value_cansleep(ts_nbus->csn, 1);  in ts_nbus_write()
256 	while (gpiod_get_value_cansleep(ts_nbus->rdy) != 0) {  in ts_nbus_write()
257 		gpiod_set_value_cansleep(ts_nbus->csn, 0);  in ts_nbus_write()
258 		gpiod_set_value_cansleep(ts_nbus->csn, 1);  in ts_nbus_write()
261 	mutex_unlock(&ts_nbus->lock);  in ts_nbus_write()
271 	struct device *dev = &pdev->dev;  in ts_nbus_probe()
277 		return -ENOMEM;  in ts_nbus_probe()
279 	mutex_init(&ts_nbus->lock);  in ts_nbus_probe()
292 		return dev_err_probe(dev, -EINVAL, "invalid PWM period\n");  in ts_nbus_probe()
304 	ts_nbus->pwm = pwm;  in ts_nbus_probe()
307 	 * let the child nodes retrieve this instance of the ts-nbus.  in ts_nbus_probe()
311 	ret = of_platform_populate(dev->of_node, NULL, NULL, dev);  in ts_nbus_probe()
323 	struct ts_nbus *ts_nbus = dev_get_drvdata(&pdev->dev);  in ts_nbus_remove()
326 	mutex_lock(&ts_nbus->lock);  in ts_nbus_remove()
327 	pwm_disable(ts_nbus->pwm);  in ts_nbus_remove()
328 	mutex_unlock(&ts_nbus->lock);  in ts_nbus_remove()
332 	{ .compatible = "technologic,ts-nbus", },