2  * NBUS driver for TS-4600 based boards
4  * Copyright (c) 2016 - Savoir-faire Linux
11  * This driver implements a GPIOs bit-banged bus, called the NBUS by Technologic
13  * TS-4600 SoM.
24 #include <linux/ts-nbus.h>
33 	struct gpio_descs *data;  member
43  * request all gpios required by the bus.
48 	ts_nbus->data = devm_gpiod_get_array(&pdev->dev, "ts,data",  in ts_nbus_init_pdata()
50 	if (IS_ERR(ts_nbus->data)) {  in ts_nbus_init_pdata()
51 		dev_err(&pdev->dev, "failed to retrieve ts,data-gpio from dts\n");  in ts_nbus_init_pdata()
52 		return PTR_ERR(ts_nbus->data);  in ts_nbus_init_pdata()
55 	ts_nbus->csn = devm_gpiod_get(&pdev->dev, "ts,csn", GPIOD_OUT_HIGH);  in ts_nbus_init_pdata()
56 	if (IS_ERR(ts_nbus->csn)) {  in ts_nbus_init_pdata()
57 		dev_err(&pdev->dev, "failed to retrieve ts,csn-gpio from dts\n");  in ts_nbus_init_pdata()
58 		return PTR_ERR(ts_nbus->csn);  in ts_nbus_init_pdata()
61 	ts_nbus->txrx = devm_gpiod_get(&pdev->dev, "ts,txrx", GPIOD_OUT_HIGH);  in ts_nbus_init_pdata()
62 	if (IS_ERR(ts_nbus->txrx)) {  in ts_nbus_init_pdata()
63 		dev_err(&pdev->dev, "failed to retrieve ts,txrx-gpio from dts\n");  in ts_nbus_init_pdata()
64 		return PTR_ERR(ts_nbus->txrx);  in ts_nbus_init_pdata()
67 	ts_nbus->strobe = devm_gpiod_get(&pdev->dev, "ts,strobe", GPIOD_OUT_HIGH);  in ts_nbus_init_pdata()
68 	if (IS_ERR(ts_nbus->strobe)) {  in ts_nbus_init_pdata()
69 		dev_err(&pdev->dev, "failed to retrieve ts,strobe-gpio from dts\n");  in ts_nbus_init_pdata()
70 		return PTR_ERR(ts_nbus->strobe);  in ts_nbus_init_pdata()
73 	ts_nbus->ale = devm_gpiod_get(&pdev->dev, "ts,ale", GPIOD_OUT_HIGH);  in ts_nbus_init_pdata()
74 	if (IS_ERR(ts_nbus->ale)) {  in ts_nbus_init_pdata()
75 		dev_err(&pdev->dev, "failed to retrieve ts,ale-gpio from dts\n");  in ts_nbus_init_pdata()
76 		return PTR_ERR(ts_nbus->ale);  in ts_nbus_init_pdata()
79 	ts_nbus->rdy = devm_gpiod_get(&pdev->dev, "ts,rdy", GPIOD_IN);  in ts_nbus_init_pdata()
80 	if (IS_ERR(ts_nbus->rdy)) {  in ts_nbus_init_pdata()
81 		dev_err(&pdev->dev, "failed to retrieve ts,rdy-gpio from dts\n");  in ts_nbus_init_pdata()
82 		return PTR_ERR(ts_nbus->rdy);  in ts_nbus_init_pdata()
89  * the data gpios are used for reading and writing values, their directions
98 			gpiod_direction_input(ts_nbus->data->desc[i]);  in ts_nbus_set_direction()
100 			/* when used as output the default state of the data  in ts_nbus_set_direction()
102 			gpiod_direction_output(ts_nbus->data->desc[i], 1);  in ts_nbus_set_direction()
108  * The data, csn, strobe and ale lines must be zero'ed to let the FPGA knows a
119 	gpiod_set_array_value_cansleep(8, ts_nbus->data->desc, values);  in ts_nbus_reset_bus()
120 	gpiod_set_value_cansleep(ts_nbus->csn, 0);  in ts_nbus_reset_bus()
121 	gpiod_set_value_cansleep(ts_nbus->strobe, 0);  in ts_nbus_reset_bus()
122 	gpiod_set_value_cansleep(ts_nbus->ale, 0);  in ts_nbus_reset_bus()
130 	gpiod_set_value_cansleep(ts_nbus->strobe, 1);  in ts_nbus_start_transaction()
134  * read a byte value from the data gpios.
139 	struct gpio_descs *gpios = ts_nbus->data;  in ts_nbus_read_byte()  local
144 		ret = gpiod_get_value_cansleep(gpios->desc[i]);  in ts_nbus_read_byte()
155  * set the data gpios accordingly to the byte value.
159 	struct gpio_descs *gpios = ts_nbus->data;  in ts_nbus_write_byte()  local
169 	gpiod_set_array_value_cansleep(8, gpios->desc, values);  in ts_nbus_write_byte()
174  * send the data in the data gpios and return the read value.
187  * command (address/value), write the data and notify the FPGA to retrieve the
188  * value in the data gpios.
195 		gpiod_set_value_cansleep(ts_nbus->ale, 1);  in ts_nbus_write_bus()
211 	mutex_lock(&ts_nbus->lock);  in ts_nbus_read()
214 	gpiod_set_value_cansleep(ts_nbus->txrx, 0);  in ts_nbus_read()
219 	/* set the data gpios direction as input before reading */  in ts_nbus_read()
222 	/* reading value MSB first */  in ts_nbus_read()
226 		for (i = 1; i >= 0; i--) {  in ts_nbus_read()
235 		gpiod_set_value_cansleep(ts_nbus->csn, 1);  in ts_nbus_read()
236 		ret = gpiod_get_value_cansleep(ts_nbus->rdy);  in ts_nbus_read()
240 	/* restore the data gpios direction as output after reading */  in ts_nbus_read()
243 	mutex_unlock(&ts_nbus->lock);  in ts_nbus_read()
257 	mutex_lock(&ts_nbus->lock);  in ts_nbus_write()
260 	gpiod_set_value_cansleep(ts_nbus->txrx, 1);  in ts_nbus_write()
265 	/* writing value MSB first */  in ts_nbus_write()
266 	for (i = 1; i >= 0; i--)  in ts_nbus_write()
270 	gpiod_set_value_cansleep(ts_nbus->csn, 1);  in ts_nbus_write()
271 	while (gpiod_get_value_cansleep(ts_nbus->rdy) != 0) {  in ts_nbus_write()
272 		gpiod_set_value_cansleep(ts_nbus->csn, 0);  in ts_nbus_write()
273 		gpiod_set_value_cansleep(ts_nbus->csn, 1);  in ts_nbus_write()
276 	mutex_unlock(&ts_nbus->lock);  in ts_nbus_write()
286 	struct device *dev = &pdev->dev;  in ts_nbus_probe()
292 		return -ENOMEM;  in ts_nbus_probe()
294 	mutex_init(&ts_nbus->lock);  in ts_nbus_probe()
303 		if (ret != -EPROBE_DEFER)  in ts_nbus_probe()
310 		dev_err(&pdev->dev, "invalid PWM period\n");  in ts_nbus_probe()
311 		return -EINVAL;  in ts_nbus_probe()
327 	ts_nbus->pwm = pwm;  in ts_nbus_probe()
330 	 * let the child nodes retrieve this instance of the ts-nbus.  in ts_nbus_probe()
334 	ret = of_platform_populate(dev->of_node, NULL, NULL, dev);  in ts_nbus_probe()
345 	struct ts_nbus *ts_nbus = dev_get_drvdata(&pdev->dev);  in ts_nbus_remove()
348 	mutex_lock(&ts_nbus->lock);  in ts_nbus_remove()
349 	pwm_disable(ts_nbus->pwm);  in ts_nbus_remove()
350 	mutex_unlock(&ts_nbus->lock);  in ts_nbus_remove()
356 	{ .compatible = "technologic,ts-nbus", },