[linux-block.git] / drivers / bus / ts-nbus.c

/*
 * NBUS driver for TS-4600 based boards
 *
 * Copyright (c) 2016 - Savoir-faire Linux
 * Author: Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 *
 * This driver implements a GPIOs bit-banged bus, called the NBUS by Technologic
 * Systems. It is used to communicate with the peripherals in the FPGA on the
 * TS-4600 SoM.
 */

#include <linux/bitops.h>
#include <linux/gpio/consumer.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/ts-nbus.h>

#define TS_NBUS_DIRECTION_IN  0
#define TS_NBUS_DIRECTION_OUT 1
#define TS_NBUS_WRITE_ADR 0
#define TS_NBUS_WRITE_VAL 1

struct ts_nbus {
	struct pwm_device *pwm;
	struct gpio_descs *data;
	struct gpio_desc *csn;
	struct gpio_desc *txrx;
	struct gpio_desc *strobe;
	struct gpio_desc *ale;
	struct gpio_desc *rdy;
	struct mutex lock;
};

/*
 * request all gpios required by the bus.
 */
static int ts_nbus_init_pdata(struct platform_device *pdev, struct ts_nbus
		*ts_nbus)
{
	ts_nbus->data = devm_gpiod_get_array(&pdev->dev, "ts,data",
			GPIOD_OUT_HIGH);
	if (IS_ERR(ts_nbus->data)) {
		dev_err(&pdev->dev, "failed to retrieve ts,data-gpio from dts\n");
		return PTR_ERR(ts_nbus->data);
	}

	ts_nbus->csn = devm_gpiod_get(&pdev->dev, "ts,csn", GPIOD_OUT_HIGH);
	if (IS_ERR(ts_nbus->csn)) {
		dev_err(&pdev->dev, "failed to retrieve ts,csn-gpio from dts\n");
		return PTR_ERR(ts_nbus->csn);
	}

	ts_nbus->txrx = devm_gpiod_get(&pdev->dev, "ts,txrx", GPIOD_OUT_HIGH);
	if (IS_ERR(ts_nbus->txrx)) {
		dev_err(&pdev->dev, "failed to retrieve ts,txrx-gpio from dts\n");
		return PTR_ERR(ts_nbus->txrx);
	}

	ts_nbus->strobe = devm_gpiod_get(&pdev->dev, "ts,strobe", GPIOD_OUT_HIGH);
	if (IS_ERR(ts_nbus->strobe)) {
		dev_err(&pdev->dev, "failed to retrieve ts,strobe-gpio from dts\n");
		return PTR_ERR(ts_nbus->strobe);
	}

	ts_nbus->ale = devm_gpiod_get(&pdev->dev, "ts,ale", GPIOD_OUT_HIGH);
	if (IS_ERR(ts_nbus->ale)) {
		dev_err(&pdev->dev, "failed to retrieve ts,ale-gpio from dts\n");
		return PTR_ERR(ts_nbus->ale);
	}

	ts_nbus->rdy = devm_gpiod_get(&pdev->dev, "ts,rdy", GPIOD_IN);
	if (IS_ERR(ts_nbus->rdy)) {
		dev_err(&pdev->dev, "failed to retrieve ts,rdy-gpio from dts\n");
		return PTR_ERR(ts_nbus->rdy);
	}

	return 0;
}

/*
 * the data gpios are used for reading and writing values, their directions
 * should be adjusted accordingly.
 */
static void ts_nbus_set_direction(struct ts_nbus *ts_nbus, int direction)
{
	int i;

	for (i = 0; i < 8; i++) {
		if (direction == TS_NBUS_DIRECTION_IN)
			gpiod_direction_input(ts_nbus->data->desc[i]);
		else
			/* when used as output the default state of the data
			 * lines are set to high */
			gpiod_direction_output(ts_nbus->data->desc[i], 1);
	}
}

/*
 * reset the bus in its initial state.
 * The data, csn, strobe and ale lines must be zero'ed to let the FPGA knows a
 * new transaction can be process.
 */
static void ts_nbus_reset_bus(struct ts_nbus *ts_nbus)
{
	DECLARE_BITMAP(values, 8);

	values[0] = 0;

	gpiod_set_array_value_cansleep(8, ts_nbus->data->desc, values);
	gpiod_set_value_cansleep(ts_nbus->csn, 0);
	gpiod_set_value_cansleep(ts_nbus->strobe, 0);
	gpiod_set_value_cansleep(ts_nbus->ale, 0);
}

/*
 * let the FPGA knows it can process.
 */
static void ts_nbus_start_transaction(struct ts_nbus *ts_nbus)
{
	gpiod_set_value_cansleep(ts_nbus->strobe, 1);
}

/*
 * read a byte value from the data gpios.
 * return 0 on success or negative errno on failure.
 */
static int ts_nbus_read_byte(struct ts_nbus *ts_nbus, u8 *val)
{
	struct gpio_descs *gpios = ts_nbus->data;
	int ret, i;

	*val = 0;
	for (i = 0; i < 8; i++) {
		ret = gpiod_get_value_cansleep(gpios->desc[i]);
		if (ret < 0)
			return ret;
		if (ret)
			*val |= BIT(i);
	}

	return 0;
}

/*
 * set the data gpios accordingly to the byte value.
 */
static void ts_nbus_write_byte(struct ts_nbus *ts_nbus, u8 byte)
{
	struct gpio_descs *gpios = ts_nbus->data;
	DECLARE_BITMAP(values, 8);

	values[0] = byte;

	gpiod_set_array_value_cansleep(8, gpios->desc, values);
}

/*
 * reading the bus consists of resetting the bus, then notifying the FPGA to
 * send the data in the data gpios and return the read value.
 * return 0 on success or negative errno on failure.
 */
static int ts_nbus_read_bus(struct ts_nbus *ts_nbus, u8 *val)
{
	ts_nbus_reset_bus(ts_nbus);
	ts_nbus_start_transaction(ts_nbus);

	return ts_nbus_read_byte(ts_nbus, val);
}

/*
 * writing to the bus consists of resetting the bus, then define the type of
 * command (address/value), write the data and notify the FPGA to retrieve the
 * value in the data gpios.
 */
static void ts_nbus_write_bus(struct ts_nbus *ts_nbus, int cmd, u8 val)
{
	ts_nbus_reset_bus(ts_nbus);

	if (cmd == TS_NBUS_WRITE_ADR)
		gpiod_set_value_cansleep(ts_nbus->ale, 1);

	ts_nbus_write_byte(ts_nbus, val);
	ts_nbus_start_transaction(ts_nbus);
}

/*
 * read the value in the FPGA register at the given address.
 * return 0 on success or negative errno on failure.
 */
int ts_nbus_read(struct ts_nbus *ts_nbus, u8 adr, u16 *val)
{
	int ret, i;
	u8 byte;

	/* bus access must be atomic */
	mutex_lock(&ts_nbus->lock);

	/* set the bus in read mode */
	gpiod_set_value_cansleep(ts_nbus->txrx, 0);

	/* write address */
	ts_nbus_write_bus(ts_nbus, TS_NBUS_WRITE_ADR, adr);

	/* set the data gpios direction as input before reading */
	ts_nbus_set_direction(ts_nbus, TS_NBUS_DIRECTION_IN);

	/* reading value MSB first */
	do {
		*val = 0;
		byte = 0;
		for (i = 1; i >= 0; i--) {
			/* read a byte from the bus, leave on error */
			ret = ts_nbus_read_bus(ts_nbus, &byte);
			if (ret < 0)
				goto err;

			/* append the byte read to the final value */
			*val |= byte << (i * 8);
		}
		gpiod_set_value_cansleep(ts_nbus->csn, 1);
		ret = gpiod_get_value_cansleep(ts_nbus->rdy);
	} while (ret);

err:
	/* restore the data gpios direction as output after reading */
	ts_nbus_set_direction(ts_nbus, TS_NBUS_DIRECTION_OUT);

	mutex_unlock(&ts_nbus->lock);

	return ret;
}
EXPORT_SYMBOL_GPL(ts_nbus_read);

/*
 * write the desired value in the FPGA register at the given address.
 */
int ts_nbus_write(struct ts_nbus *ts_nbus, u8 adr, u16 val)
{
	int i;

	/* bus access must be atomic */
	mutex_lock(&ts_nbus->lock);

	/* set the bus in write mode */
	gpiod_set_value_cansleep(ts_nbus->txrx, 1);

	/* write address */
	ts_nbus_write_bus(ts_nbus, TS_NBUS_WRITE_ADR, adr);

	/* writing value MSB first */
	for (i = 1; i >= 0; i--)
		ts_nbus_write_bus(ts_nbus, TS_NBUS_WRITE_VAL, (u8)(val >> (i * 8)));

	/* wait for completion */
	gpiod_set_value_cansleep(ts_nbus->csn, 1);
	while (gpiod_get_value_cansleep(ts_nbus->rdy) != 0) {
		gpiod_set_value_cansleep(ts_nbus->csn, 0);
		gpiod_set_value_cansleep(ts_nbus->csn, 1);
	}

	mutex_unlock(&ts_nbus->lock);

	return 0;
}
EXPORT_SYMBOL_GPL(ts_nbus_write);

static int ts_nbus_probe(struct platform_device *pdev)
{
	struct pwm_device *pwm;
	struct pwm_args pargs;
	struct device *dev = &pdev->dev;
	struct ts_nbus *ts_nbus;
	int ret;

	ts_nbus = devm_kzalloc(dev, sizeof(*ts_nbus), GFP_KERNEL);
	if (!ts_nbus)
		return -ENOMEM;

	mutex_init(&ts_nbus->lock);

	ret = ts_nbus_init_pdata(pdev, ts_nbus);
	if (ret < 0)
		return ret;

	pwm = devm_pwm_get(dev, NULL);
	if (IS_ERR(pwm)) {
		ret = PTR_ERR(pwm);
		if (ret != -EPROBE_DEFER)
			dev_err(dev, "unable to request PWM\n");
		return ret;
	}

	pwm_get_args(pwm, &pargs);
	if (!pargs.period) {
		dev_err(&pdev->dev, "invalid PWM period\n");
		return -EINVAL;
	}

	/*
	 * FIXME: pwm_apply_args() should be removed when switching to
	 * the atomic PWM API.
	 */
	pwm_apply_args(pwm);
	ret = pwm_config(pwm, pargs.period, pargs.period);
	if (ret < 0)
		return ret;

	/*
	 * we can now start the FPGA and populate the peripherals.
	 */
	pwm_enable(pwm);
	ts_nbus->pwm = pwm;

	/*
	 * let the child nodes retrieve this instance of the ts-nbus.
	 */
	dev_set_drvdata(dev, ts_nbus);

	ret = of_platform_populate(dev->of_node, NULL, NULL, dev);
	if (ret < 0)
		return ret;

	dev_info(dev, "initialized\n");

	return 0;
}

static int ts_nbus_remove(struct platform_device *pdev)
{
	struct ts_nbus *ts_nbus = dev_get_drvdata(&pdev->dev);

	/* shutdown the FPGA */
	mutex_lock(&ts_nbus->lock);
	pwm_disable(ts_nbus->pwm);
	mutex_unlock(&ts_nbus->lock);

	return 0;
}

static const struct of_device_id ts_nbus_of_match[] = {
	{ .compatible = "technologic,ts-nbus", },
	{ },
};
MODULE_DEVICE_TABLE(of, ts_nbus_of_match);

static struct platform_driver ts_nbus_driver = {
	.probe		= ts_nbus_probe,
	.remove		= ts_nbus_remove,
	.driver		= {
		.name	= "ts_nbus",
		.of_match_table = ts_nbus_of_match,
	},
};

module_platform_driver(ts_nbus_driver);

MODULE_ALIAS("platform:ts_nbus");
MODULE_AUTHOR("Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com>");
MODULE_DESCRIPTION("Technologic Systems NBUS");
MODULE_LICENSE("GPL v2");
Commit	Line	Data
5b143d2a SB	1	/*
	2	* NBUS driver for TS-4600 based boards
	3	*
	4	* Copyright (c) 2016 - Savoir-faire Linux
	5	* Author: Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com>
	6	*
	7	* This file is licensed under the terms of the GNU General Public
	8	* License version 2. This program is licensed "as is" without any
	9	* warranty of any kind, whether express or implied.
	10	*
	11	* This driver implements a GPIOs bit-banged bus, called the NBUS by Technologic
	12	* Systems. It is used to communicate with the peripherals in the FPGA on the
	13	* TS-4600 SoM.
	14	*/
	15
	16	#include <linux/bitops.h>
	17	#include <linux/gpio/consumer.h>
	18	#include <linux/kernel.h>
	19	#include <linux/module.h>
	20	#include <linux/mutex.h>
	21	#include <linux/of_platform.h>
	22	#include <linux/platform_device.h>
	23	#include <linux/pwm.h>
	24	#include <linux/ts-nbus.h>
	25
	26	#define TS_NBUS_DIRECTION_IN 0
	27	#define TS_NBUS_DIRECTION_OUT 1
	28	#define TS_NBUS_WRITE_ADR 0
	29	#define TS_NBUS_WRITE_VAL 1
	30
	31	struct ts_nbus {
	32	struct pwm_device *pwm;
	33	struct gpio_descs *data;
	34	struct gpio_desc *csn;
	35	struct gpio_desc *txrx;
	36	struct gpio_desc *strobe;
	37	struct gpio_desc *ale;
	38	struct gpio_desc *rdy;
	39	struct mutex lock;
	40	};
	41
	42	/*
	43	* request all gpios required by the bus.
	44	*/
	45	static int ts_nbus_init_pdata(struct platform_device *pdev, struct ts_nbus
	46	*ts_nbus)
	47	{
	48	ts_nbus->data = devm_gpiod_get_array(&pdev->dev, "ts,data",
	49	GPIOD_OUT_HIGH);
	50	if (IS_ERR(ts_nbus->data)) {
	51	dev_err(&pdev->dev, "failed to retrieve ts,data-gpio from dts\n");
	52	return PTR_ERR(ts_nbus->data);
	53	}
	54
	55	ts_nbus->csn = devm_gpiod_get(&pdev->dev, "ts,csn", GPIOD_OUT_HIGH);
	56	if (IS_ERR(ts_nbus->csn)) {
	57	dev_err(&pdev->dev, "failed to retrieve ts,csn-gpio from dts\n");
	58	return PTR_ERR(ts_nbus->csn);
	59	}
	60
	61	ts_nbus->txrx = devm_gpiod_get(&pdev->dev, "ts,txrx", GPIOD_OUT_HIGH);
	62	if (IS_ERR(ts_nbus->txrx)) {
	63	dev_err(&pdev->dev, "failed to retrieve ts,txrx-gpio from dts\n");
	64	return PTR_ERR(ts_nbus->txrx);
65	}
66
67	ts_nbus->strobe = devm_gpiod_get(&pdev->dev, "ts,strobe", GPIOD_OUT_HIGH);
68	if (IS_ERR(ts_nbus->strobe)) {
69	dev_err(&pdev->dev, "failed to retrieve ts,strobe-gpio from dts\n");
70	return PTR_ERR(ts_nbus->strobe);
71	}
72
73	ts_nbus->ale = devm_gpiod_get(&pdev->dev, "ts,ale", GPIOD_OUT_HIGH);
74	if (IS_ERR(ts_nbus->ale)) {
75	dev_err(&pdev->dev, "failed to retrieve ts,ale-gpio from dts\n");
76	return PTR_ERR(ts_nbus->ale);
77	}
78
79	ts_nbus->rdy = devm_gpiod_get(&pdev->dev, "ts,rdy", GPIOD_IN);
80	if (IS_ERR(ts_nbus->rdy)) {
81	dev_err(&pdev->dev, "failed to retrieve ts,rdy-gpio from dts\n");
82	return PTR_ERR(ts_nbus->rdy);
83	}
84
85	return 0;
86	}
87
88	/*
89	* the data gpios are used for reading and writing values, their directions
90	* should be adjusted accordingly.
91	*/
92	static void ts_nbus_set_direction(struct ts_nbus *ts_nbus, int direction)
93	{
94	int i;
95
96	for (i = 0; i < 8; i++) {
97	if (direction == TS_NBUS_DIRECTION_IN)
98	gpiod_direction_input(ts_nbus->data->desc[i]);
99	else
100	/* when used as output the default state of the data
101	* lines are set to high */
102	gpiod_direction_output(ts_nbus->data->desc[i], 1);
103	}
104	}
105
106	/*
107	* reset the bus in its initial state.
108	* The data, csn, strobe and ale lines must be zero'ed to let the FPGA knows a
109	* new transaction can be process.
110	*/
111	static void ts_nbus_reset_bus(struct ts_nbus *ts_nbus)
112	{
b9762beb	113	DECLARE_BITMAP(values, 8);
5b143d2a	114
b9762beb	115	values[0] = 0;
5b143d2a SB	116
	117	gpiod_set_array_value_cansleep(8, ts_nbus->data->desc, values);
	118	gpiod_set_value_cansleep(ts_nbus->csn, 0);
	119	gpiod_set_value_cansleep(ts_nbus->strobe, 0);
	120	gpiod_set_value_cansleep(ts_nbus->ale, 0);
	121	}
	122
	123	/*
	124	* let the FPGA knows it can process.
	125	*/
	126	static void ts_nbus_start_transaction(struct ts_nbus *ts_nbus)
	127	{
	128	gpiod_set_value_cansleep(ts_nbus->strobe, 1);
	129	}
	130
	131	/*
	132	* read a byte value from the data gpios.
	133	* return 0 on success or negative errno on failure.
	134	*/
	135	static int ts_nbus_read_byte(struct ts_nbus ts_nbus, u8 val)
	136	{
	137	struct gpio_descs *gpios = ts_nbus->data;
	138	int ret, i;
	139
	140	*val = 0;
	141	for (i = 0; i < 8; i++) {
	142	ret = gpiod_get_value_cansleep(gpios->desc[i]);
	143	if (ret < 0)
	144	return ret;
	145	if (ret)
	146	*val \|= BIT(i);
	147	}
	148
	149	return 0;
	150	}
	151
	152	/*
	153	* set the data gpios accordingly to the byte value.
	154	*/
	155	static void ts_nbus_write_byte(struct ts_nbus *ts_nbus, u8 byte)
	156	{
	157	struct gpio_descs *gpios = ts_nbus->data;
b9762beb	158	DECLARE_BITMAP(values, 8);
5b143d2a	159
b9762beb	160	values[0] = byte;
5b143d2a SB	161
	162	gpiod_set_array_value_cansleep(8, gpios->desc, values);
	163	}
	164
	165	/*
	166	* reading the bus consists of resetting the bus, then notifying the FPGA to
	167	* send the data in the data gpios and return the read value.
	168	* return 0 on success or negative errno on failure.
	169	*/
	170	static int ts_nbus_read_bus(struct ts_nbus ts_nbus, u8 val)
	171	{
	172	ts_nbus_reset_bus(ts_nbus);
	173	ts_nbus_start_transaction(ts_nbus);
	174
	175	return ts_nbus_read_byte(ts_nbus, val);
	176	}
	177
	178	/*
	179	* writing to the bus consists of resetting the bus, then define the type of
	180	* command (address/value), write the data and notify the FPGA to retrieve the
	181	* value in the data gpios.
	182	*/
	183	static void ts_nbus_write_bus(struct ts_nbus *ts_nbus, int cmd, u8 val)
	184	{
	185	ts_nbus_reset_bus(ts_nbus);
	186
	187	if (cmd == TS_NBUS_WRITE_ADR)
	188	gpiod_set_value_cansleep(ts_nbus->ale, 1);
	189
	190	ts_nbus_write_byte(ts_nbus, val);
	191	ts_nbus_start_transaction(ts_nbus);
	192	}
	193
	194	/*
	195	* read the value in the FPGA register at the given address.
	196	* return 0 on success or negative errno on failure.
	197	*/
	198	int ts_nbus_read(struct ts_nbus ts_nbus, u8 adr, u16 val)
	199	{
	200	int ret, i;
	201	u8 byte;
	202
	203	/* bus access must be atomic */
	204	mutex_lock(&ts_nbus->lock);
	205
	206	/* set the bus in read mode */
	207	gpiod_set_value_cansleep(ts_nbus->txrx, 0);
	208
	209	/* write address */
	210	ts_nbus_write_bus(ts_nbus, TS_NBUS_WRITE_ADR, adr);
	211
	212	/* set the data gpios direction as input before reading */
	213	ts_nbus_set_direction(ts_nbus, TS_NBUS_DIRECTION_IN);
	214
	215	/* reading value MSB first */
	216	do {
	217	*val = 0;
	218	byte = 0;
	219	for (i = 1; i >= 0; i--) {
	220	/* read a byte from the bus, leave on error */
	221	ret = ts_nbus_read_bus(ts_nbus, &byte);
	222	if (ret < 0)
	223	goto err;
	224
225	/* append the byte read to the final value */
226	val \|= byte << (i 8);
227	}
228	gpiod_set_value_cansleep(ts_nbus->csn, 1);
229	ret = gpiod_get_value_cansleep(ts_nbus->rdy);
230	} while (ret);
231
232	err:
233	/* restore the data gpios direction as output after reading */
234	ts_nbus_set_direction(ts_nbus, TS_NBUS_DIRECTION_OUT);
235
236	mutex_unlock(&ts_nbus->lock);
237
238	return ret;
239	}
240	EXPORT_SYMBOL_GPL(ts_nbus_read);
241
242	/*
243	* write the desired value in the FPGA register at the given address.
244	*/
245	int ts_nbus_write(struct ts_nbus *ts_nbus, u8 adr, u16 val)
246	{
247	int i;
248
249	/* bus access must be atomic */
250	mutex_lock(&ts_nbus->lock);
251
252	/* set the bus in write mode */
253	gpiod_set_value_cansleep(ts_nbus->txrx, 1);
254
255	/* write address */
256	ts_nbus_write_bus(ts_nbus, TS_NBUS_WRITE_ADR, adr);
257
258	/* writing value MSB first */
259	for (i = 1; i >= 0; i--)
260	ts_nbus_write_bus(ts_nbus, TS_NBUS_WRITE_VAL, (u8)(val >> (i * 8)));
261
262	/* wait for completion */
263	gpiod_set_value_cansleep(ts_nbus->csn, 1);
264	while (gpiod_get_value_cansleep(ts_nbus->rdy) != 0) {
265	gpiod_set_value_cansleep(ts_nbus->csn, 0);
266	gpiod_set_value_cansleep(ts_nbus->csn, 1);
267	}
268
269	mutex_unlock(&ts_nbus->lock);
270
271	return 0;
272	}
273	EXPORT_SYMBOL_GPL(ts_nbus_write);
274
275	static int ts_nbus_probe(struct platform_device *pdev)
276	{
277	struct pwm_device *pwm;
278	struct pwm_args pargs;
279	struct device *dev = &pdev->dev;
280	struct ts_nbus *ts_nbus;
281	int ret;
282
283	ts_nbus = devm_kzalloc(dev, sizeof(*ts_nbus), GFP_KERNEL);
284	if (!ts_nbus)
285	return -ENOMEM;
286
287	mutex_init(&ts_nbus->lock);
288
289	ret = ts_nbus_init_pdata(pdev, ts_nbus);
290	if (ret < 0)
291	return ret;
292
293	pwm = devm_pwm_get(dev, NULL);
294	if (IS_ERR(pwm)) {
295	ret = PTR_ERR(pwm);
296	if (ret != -EPROBE_DEFER)
297	dev_err(dev, "unable to request PWM\n");
298	return ret;
299	}
300
301	pwm_get_args(pwm, &pargs);
302	if (!pargs.period) {
303	dev_err(&pdev->dev, "invalid PWM period\n");
304	return -EINVAL;
305	}
306
307	/*
308	* FIXME: pwm_apply_args() should be removed when switching to
309	* the atomic PWM API.
310	*/
311	pwm_apply_args(pwm);
312	ret = pwm_config(pwm, pargs.period, pargs.period);
313	if (ret < 0)
314	return ret;
315
316	/*
317	* we can now start the FPGA and populate the peripherals.
318	*/
319	pwm_enable(pwm);
320	ts_nbus->pwm = pwm;
321
322	/*
323	* let the child nodes retrieve this instance of the ts-nbus.
324	*/
325	dev_set_drvdata(dev, ts_nbus);
326
327	ret = of_platform_populate(dev->of_node, NULL, NULL, dev);
328	if (ret < 0)
329	return ret;
330
331	dev_info(dev, "initialized\n");
332
333	return 0;
334	}
335
336	static int ts_nbus_remove(struct platform_device *pdev)
337	{
338	struct ts_nbus *ts_nbus = dev_get_drvdata(&pdev->dev);
339
340	/* shutdown the FPGA */
341	mutex_lock(&ts_nbus->lock);
342	pwm_disable(ts_nbus->pwm);
343	mutex_unlock(&ts_nbus->lock);
344
345	return 0;
346	}
347
348	static const struct of_device_id ts_nbus_of_match[] = {
349	{ .compatible = "technologic,ts-nbus", },
350	{ },
351	};
352	MODULE_DEVICE_TABLE(of, ts_nbus_of_match);
353
354	static struct platform_driver ts_nbus_driver = {
355	.probe = ts_nbus_probe,
356	.remove = ts_nbus_remove,
357	.driver = {
358	.name = "ts_nbus",
359	.of_match_table = ts_nbus_of_match,
360	},
361	};
362
363	module_platform_driver(ts_nbus_driver);
364
365	MODULE_ALIAS("platform:ts_nbus");
366	MODULE_AUTHOR("Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com>");
367	MODULE_DESCRIPTION("Technologic Systems NBUS");
368	MODULE_LICENSE("GPL v2");