1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * NXP SC18IS602/603 SPI driver
4 *
5 * Copyright (C) Guenter Roeck <linux@roeck-us.net>
6 */
7
8#include <linux/kernel.h>
9#include <linux/err.h>
10#include <linux/module.h>
11#include <linux/spi/spi.h>
12#include <linux/i2c.h>
13#include <linux/delay.h>
14#include <linux/pm_runtime.h>
15#include <linux/of_device.h>
16#include <linux/of.h>
17#include <linux/platform_data/sc18is602.h>
18#include <linux/gpio/consumer.h>
19
20enum chips { sc18is602, sc18is602b, sc18is603 };
21
22#define SC18IS602_BUFSIZ		200
23#define SC18IS602_CLOCK			7372000
24
25#define SC18IS602_MODE_CPHA		BIT(2)
26#define SC18IS602_MODE_CPOL		BIT(3)
27#define SC18IS602_MODE_LSB_FIRST	BIT(5)
28#define SC18IS602_MODE_CLOCK_DIV_4	0x0
29#define SC18IS602_MODE_CLOCK_DIV_16	0x1
30#define SC18IS602_MODE_CLOCK_DIV_64	0x2
31#define SC18IS602_MODE_CLOCK_DIV_128	0x3
32
33struct sc18is602 {
34	struct spi_master	*master;
35	struct device		*dev;
36	u8			ctrl;
37	u32			freq;
38	u32			speed;
39
40	/* I2C data */
41	struct i2c_client	*client;
42	enum chips		id;
43	u8			buffer[SC18IS602_BUFSIZ + 1];
44	int			tlen;	/* Data queued for tx in buffer */
45	int			rindex;	/* Receive data index in buffer */
46
47	struct gpio_desc	*reset;
48};
49
50static int sc18is602_wait_ready(struct sc18is602 *hw, int len)
51{
52	int i, err;
53	int usecs = 1000000 * len / hw->speed + 1;
54	u8 dummy[1];
55
56	for (i = 0; i < 10; i++) {
57		err = i2c_master_recv(hw->client, dummy, 1);
58		if (err >= 0)
59			return 0;
60		usleep_range(usecs, usecs * 2);
61	}
62	return -ETIMEDOUT;
63}
64
65static int sc18is602_txrx(struct sc18is602 *hw, struct spi_message *msg,
66			  struct spi_transfer *t, bool do_transfer)
67{
68	unsigned int len = t->len;
69	int ret;
70
71	if (hw->tlen == 0) {
72		/* First byte (I2C command) is chip select */
73		hw->buffer[0] = 1 << msg->spi->chip_select;
74		hw->tlen = 1;
75		hw->rindex = 0;
76	}
77	/*
78	 * We can not immediately send data to the chip, since each I2C message
79	 * resembles a full SPI message (from CS active to CS inactive).
80	 * Enqueue messages up to the first read or until do_transfer is true.
81	 */
82	if (t->tx_buf) {
83		memcpy(&hw->buffer[hw->tlen], t->tx_buf, len);
84		hw->tlen += len;
85		if (t->rx_buf)
86			do_transfer = true;
87		else
88			hw->rindex = hw->tlen - 1;
89	} else if (t->rx_buf) {
90		/*
91		 * For receive-only transfers we still need to perform a dummy
92		 * write to receive data from the SPI chip.
93		 * Read data starts at the end of transmit data (minus 1 to
94		 * account for CS).
95		 */
96		hw->rindex = hw->tlen - 1;
97		memset(&hw->buffer[hw->tlen], 0, len);
98		hw->tlen += len;
99		do_transfer = true;
100	}
101
102	if (do_transfer && hw->tlen > 1) {
103		ret = sc18is602_wait_ready(hw, SC18IS602_BUFSIZ);
104		if (ret < 0)
105			return ret;
106		ret = i2c_master_send(hw->client, hw->buffer, hw->tlen);
107		if (ret < 0)
108			return ret;
109		if (ret != hw->tlen)
110			return -EIO;
111
112		if (t->rx_buf) {
113			int rlen = hw->rindex + len;
114
115			ret = sc18is602_wait_ready(hw, hw->tlen);
116			if (ret < 0)
117				return ret;
118			ret = i2c_master_recv(hw->client, hw->buffer, rlen);
119			if (ret < 0)
120				return ret;
121			if (ret != rlen)
122				return -EIO;
123			memcpy(t->rx_buf, &hw->buffer[hw->rindex], len);
124		}
125		hw->tlen = 0;
126	}
127	return len;
128}
129
130static int sc18is602_setup_transfer(struct sc18is602 *hw, u32 hz, u8 mode)
131{
132	u8 ctrl = 0;
133	int ret;
134
135	if (mode & SPI_CPHA)
136		ctrl |= SC18IS602_MODE_CPHA;
137	if (mode & SPI_CPOL)
138		ctrl |= SC18IS602_MODE_CPOL;
139	if (mode & SPI_LSB_FIRST)
140		ctrl |= SC18IS602_MODE_LSB_FIRST;
141
142	/* Find the closest clock speed */
143	if (hz >= hw->freq / 4) {
144		ctrl |= SC18IS602_MODE_CLOCK_DIV_4;
145		hw->speed = hw->freq / 4;
146	} else if (hz >= hw->freq / 16) {
147		ctrl |= SC18IS602_MODE_CLOCK_DIV_16;
148		hw->speed = hw->freq / 16;
149	} else if (hz >= hw->freq / 64) {
150		ctrl |= SC18IS602_MODE_CLOCK_DIV_64;
151		hw->speed = hw->freq / 64;
152	} else {
153		ctrl |= SC18IS602_MODE_CLOCK_DIV_128;
154		hw->speed = hw->freq / 128;
155	}
156
157	/*
158	 * Don't do anything if the control value did not change. The initial
159	 * value of 0xff for hw->ctrl ensures that the correct mode will be set
160	 * with the first call to this function.
161	 */
162	if (ctrl == hw->ctrl)
163		return 0;
164
165	ret = i2c_smbus_write_byte_data(hw->client, 0xf0, ctrl);
166	if (ret < 0)
167		return ret;
168
169	hw->ctrl = ctrl;
170
171	return 0;
172}
173
174static int sc18is602_check_transfer(struct spi_device *spi,
175				    struct spi_transfer *t, int tlen)
176{
177	if (t && t->len + tlen > SC18IS602_BUFSIZ)
178		return -EINVAL;
179
180	return 0;
181}
182
183static int sc18is602_transfer_one(struct spi_master *master,
184				  struct spi_message *m)
185{
186	struct sc18is602 *hw = spi_master_get_devdata(master);
187	struct spi_device *spi = m->spi;
188	struct spi_transfer *t;
189	int status = 0;
190
191	hw->tlen = 0;
192	list_for_each_entry(t, &m->transfers, transfer_list) {
193		bool do_transfer;
194
195		status = sc18is602_check_transfer(spi, t, hw->tlen);
196		if (status < 0)
197			break;
198
199		status = sc18is602_setup_transfer(hw, t->speed_hz, spi->mode);
200		if (status < 0)
201			break;
202
203		do_transfer = t->cs_change || list_is_last(&t->transfer_list,
204							   &m->transfers);
205
206		if (t->len) {
207			status = sc18is602_txrx(hw, m, t, do_transfer);
208			if (status < 0)
209				break;
210			m->actual_length += status;
211		}
212		status = 0;
213
214		spi_transfer_delay_exec(t);
215	}
216	m->status = status;
217	spi_finalize_current_message(master);
218
219	return status;
220}
221
222static int sc18is602_setup(struct spi_device *spi)
223{
224	struct sc18is602 *hw = spi_master_get_devdata(spi->master);
225
226	/* SC18IS602 does not support CS2 */
227	if (hw->id == sc18is602 && spi->chip_select == 2)
228		return -ENXIO;
229
230	return 0;
231}
232
233static int sc18is602_probe(struct i2c_client *client,
234			   const struct i2c_device_id *id)
235{
236	struct device *dev = &client->dev;
237	struct device_node *np = dev->of_node;
238	struct sc18is602_platform_data *pdata = dev_get_platdata(dev);
239	struct sc18is602 *hw;
240	struct spi_master *master;
241
242	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
243				     I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
244		return -EINVAL;
245
246	master = devm_spi_alloc_master(dev, sizeof(struct sc18is602));
247	if (!master)
248		return -ENOMEM;
249
250	hw = spi_master_get_devdata(master);
251	i2c_set_clientdata(client, hw);
252
253	/* assert reset and then release */
254	hw->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
255	if (IS_ERR(hw->reset))
256		return PTR_ERR(hw->reset);
257	gpiod_set_value_cansleep(hw->reset, 0);
258
259	hw->master = master;
260	hw->client = client;
261	hw->dev = dev;
262	hw->ctrl = 0xff;
263
264	if (client->dev.of_node)
265		hw->id = (enum chips)of_device_get_match_data(&client->dev);
266	else
267		hw->id = id->driver_data;
268
269	switch (hw->id) {
270	case sc18is602:
271	case sc18is602b:
272		master->num_chipselect = 4;
273		hw->freq = SC18IS602_CLOCK;
274		break;
275	case sc18is603:
276		master->num_chipselect = 2;
277		if (pdata) {
278			hw->freq = pdata->clock_frequency;
279		} else {
280			const __be32 *val;
281			int len;
282
283			val = of_get_property(np, "clock-frequency", &len);
284			if (val && len >= sizeof(__be32))
285				hw->freq = be32_to_cpup(val);
286		}
287		if (!hw->freq)
288			hw->freq = SC18IS602_CLOCK;
289		break;
290	}
291	master->bus_num = np ? -1 : client->adapter->nr;
292	master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_LSB_FIRST;
293	master->bits_per_word_mask = SPI_BPW_MASK(8);
294	master->setup = sc18is602_setup;
295	master->transfer_one_message = sc18is602_transfer_one;
296	master->dev.of_node = np;
297	master->min_speed_hz = hw->freq / 128;
298	master->max_speed_hz = hw->freq / 4;
299
300	return devm_spi_register_master(dev, master);
301}
302
303static const struct i2c_device_id sc18is602_id[] = {
304	{ "sc18is602", sc18is602 },
305	{ "sc18is602b", sc18is602b },
306	{ "sc18is603", sc18is603 },
307	{ }
308};
309MODULE_DEVICE_TABLE(i2c, sc18is602_id);
310
311static const struct of_device_id sc18is602_of_match[] = {
312	{
313		.compatible = "nxp,sc18is602",
314		.data = (void *)sc18is602
315	},
316	{
317		.compatible = "nxp,sc18is602b",
318		.data = (void *)sc18is602b
319	},
320	{
321		.compatible = "nxp,sc18is603",
322		.data = (void *)sc18is603
323	},
324	{ },
325};
326MODULE_DEVICE_TABLE(of, sc18is602_of_match);
327
328static struct i2c_driver sc18is602_driver = {
329	.driver = {
330		.name = "sc18is602",
331		.of_match_table = of_match_ptr(sc18is602_of_match),
332	},
333	.probe = sc18is602_probe,
334	.id_table = sc18is602_id,
335};
336
337module_i2c_driver(sc18is602_driver);
338
339MODULE_DESCRIPTION("SC18IS602/603 SPI Master Driver");
340MODULE_AUTHOR("Guenter Roeck");
341MODULE_LICENSE("GPL");
342