1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Analog Devices AD-FMCOMMS1-EBZ board I2C-SPI bridge driver
4 *
5 * Copyright 2012 Analog Devices Inc.
6 * Author: Lars-Peter Clausen <lars@metafoo.de>
7 */
8
9#include <linux/kernel.h>
10#include <linux/module.h>
11#include <linux/delay.h>
12#include <linux/i2c.h>
13#include <linux/spi/spi.h>
14#include <asm/unaligned.h>
15
16#define SPI_XCOMM_SETTINGS_LEN_OFFSET		10
17#define SPI_XCOMM_SETTINGS_3WIRE		BIT(6)
18#define SPI_XCOMM_SETTINGS_CS_HIGH		BIT(5)
19#define SPI_XCOMM_SETTINGS_SAMPLE_END		BIT(4)
20#define SPI_XCOMM_SETTINGS_CPHA			BIT(3)
21#define SPI_XCOMM_SETTINGS_CPOL			BIT(2)
22#define SPI_XCOMM_SETTINGS_CLOCK_DIV_MASK	0x3
23#define SPI_XCOMM_SETTINGS_CLOCK_DIV_64		0x2
24#define SPI_XCOMM_SETTINGS_CLOCK_DIV_16		0x1
25#define SPI_XCOMM_SETTINGS_CLOCK_DIV_4		0x0
26
27#define SPI_XCOMM_CMD_UPDATE_CONFIG	0x03
28#define SPI_XCOMM_CMD_WRITE		0x04
29
30#define SPI_XCOMM_CLOCK 48000000
31
32struct spi_xcomm {
33	struct i2c_client *i2c;
34
35	uint16_t settings;
36	uint16_t chipselect;
37
38	unsigned int current_speed;
39
40	uint8_t buf[63];
41};
42
43static int spi_xcomm_sync_config(struct spi_xcomm *spi_xcomm, unsigned int len)
44{
45	uint16_t settings;
46	uint8_t *buf = spi_xcomm->buf;
47
48	settings = spi_xcomm->settings;
49	settings |= len << SPI_XCOMM_SETTINGS_LEN_OFFSET;
50
51	buf[0] = SPI_XCOMM_CMD_UPDATE_CONFIG;
52	put_unaligned_be16(settings, &buf[1]);
53	put_unaligned_be16(spi_xcomm->chipselect, &buf[3]);
54
55	return i2c_master_send(spi_xcomm->i2c, buf, 5);
56}
57
58static void spi_xcomm_chipselect(struct spi_xcomm *spi_xcomm,
59	struct spi_device *spi, int is_active)
60{
61	unsigned long cs = spi_get_chipselect(spi, 0);
62	uint16_t chipselect = spi_xcomm->chipselect;
63
64	if (is_active)
65		chipselect |= BIT(cs);
66	else
67		chipselect &= ~BIT(cs);
68
69	spi_xcomm->chipselect = chipselect;
70}
71
72static int spi_xcomm_setup_transfer(struct spi_xcomm *spi_xcomm,
73	struct spi_device *spi, struct spi_transfer *t, unsigned int *settings)
74{
75	if (t->len > 62)
76		return -EINVAL;
77
78	if (t->speed_hz != spi_xcomm->current_speed) {
79		unsigned int divider;
80
81		divider = DIV_ROUND_UP(SPI_XCOMM_CLOCK, t->speed_hz);
82		if (divider >= 64)
83			*settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_64;
84		else if (divider >= 16)
85			*settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_16;
86		else
87			*settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_4;
88
89		spi_xcomm->current_speed = t->speed_hz;
90	}
91
92	if (spi->mode & SPI_CPOL)
93		*settings |= SPI_XCOMM_SETTINGS_CPOL;
94	else
95		*settings &= ~SPI_XCOMM_SETTINGS_CPOL;
96
97	if (spi->mode & SPI_CPHA)
98		*settings &= ~SPI_XCOMM_SETTINGS_CPHA;
99	else
100		*settings |= SPI_XCOMM_SETTINGS_CPHA;
101
102	if (spi->mode & SPI_3WIRE)
103		*settings |= SPI_XCOMM_SETTINGS_3WIRE;
104	else
105		*settings &= ~SPI_XCOMM_SETTINGS_3WIRE;
106
107	return 0;
108}
109
110static int spi_xcomm_txrx_bufs(struct spi_xcomm *spi_xcomm,
111	struct spi_device *spi, struct spi_transfer *t)
112{
113	int ret;
114
115	if (t->tx_buf) {
116		spi_xcomm->buf[0] = SPI_XCOMM_CMD_WRITE;
117		memcpy(spi_xcomm->buf + 1, t->tx_buf, t->len);
118
119		ret = i2c_master_send(spi_xcomm->i2c, spi_xcomm->buf, t->len + 1);
120		if (ret < 0)
121			return ret;
122		else if (ret != t->len + 1)
123			return -EIO;
124	} else if (t->rx_buf) {
125		ret = i2c_master_recv(spi_xcomm->i2c, t->rx_buf, t->len);
126		if (ret < 0)
127			return ret;
128		else if (ret != t->len)
129			return -EIO;
130	}
131
132	return t->len;
133}
134
135static int spi_xcomm_transfer_one(struct spi_controller *host,
136	struct spi_message *msg)
137{
138	struct spi_xcomm *spi_xcomm = spi_controller_get_devdata(host);
139	unsigned int settings = spi_xcomm->settings;
140	struct spi_device *spi = msg->spi;
141	unsigned cs_change = 0;
142	struct spi_transfer *t;
143	bool is_first = true;
144	int status = 0;
145	bool is_last;
146
147	spi_xcomm_chipselect(spi_xcomm, spi, true);
148
149	list_for_each_entry(t, &msg->transfers, transfer_list) {
150
151		if (!t->tx_buf && !t->rx_buf && t->len) {
152			status = -EINVAL;
153			break;
154		}
155
156		status = spi_xcomm_setup_transfer(spi_xcomm, spi, t, &settings);
157		if (status < 0)
158			break;
159
160		is_last = list_is_last(&t->transfer_list, &msg->transfers);
161		cs_change = t->cs_change;
162
163		if (cs_change ^ is_last)
164			settings |= BIT(5);
165		else
166			settings &= ~BIT(5);
167
168		if (t->rx_buf) {
169			spi_xcomm->settings = settings;
170			status = spi_xcomm_sync_config(spi_xcomm, t->len);
171			if (status < 0)
172				break;
173		} else if (settings != spi_xcomm->settings || is_first) {
174			spi_xcomm->settings = settings;
175			status = spi_xcomm_sync_config(spi_xcomm, 0);
176			if (status < 0)
177				break;
178		}
179
180		if (t->len) {
181			status = spi_xcomm_txrx_bufs(spi_xcomm, spi, t);
182
183			if (status < 0)
184				break;
185
186			if (status > 0)
187				msg->actual_length += status;
188		}
189		status = 0;
190
191		spi_transfer_delay_exec(t);
192
193		is_first = false;
194	}
195
196	if (status != 0 || !cs_change)
197		spi_xcomm_chipselect(spi_xcomm, spi, false);
198
199	msg->status = status;
200	spi_finalize_current_message(host);
201
202	return status;
203}
204
205static int spi_xcomm_probe(struct i2c_client *i2c)
206{
207	struct spi_xcomm *spi_xcomm;
208	struct spi_controller *host;
209	int ret;
210
211	host = spi_alloc_host(&i2c->dev, sizeof(*spi_xcomm));
212	if (!host)
213		return -ENOMEM;
214
215	spi_xcomm = spi_controller_get_devdata(host);
216	spi_xcomm->i2c = i2c;
217
218	host->num_chipselect = 16;
219	host->mode_bits = SPI_CPHA | SPI_CPOL | SPI_3WIRE;
220	host->bits_per_word_mask = SPI_BPW_MASK(8);
221	host->flags = SPI_CONTROLLER_HALF_DUPLEX;
222	host->transfer_one_message = spi_xcomm_transfer_one;
223	host->dev.of_node = i2c->dev.of_node;
224	i2c_set_clientdata(i2c, host);
225
226	ret = devm_spi_register_controller(&i2c->dev, host);
227	if (ret < 0)
228		spi_controller_put(host);
229
230	return ret;
231}
232
233static const struct i2c_device_id spi_xcomm_ids[] = {
234	{ "spi-xcomm" },
235	{ },
236};
237MODULE_DEVICE_TABLE(i2c, spi_xcomm_ids);
238
239static struct i2c_driver spi_xcomm_driver = {
240	.driver = {
241		.name	= "spi-xcomm",
242	},
243	.id_table	= spi_xcomm_ids,
244	.probe		= spi_xcomm_probe,
245};
246module_i2c_driver(spi_xcomm_driver);
247
248MODULE_LICENSE("GPL");
249MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
250MODULE_DESCRIPTION("Analog Devices AD-FMCOMMS1-EBZ board I2C-SPI bridge driver");
251