1/*
2 * Analog Devices AD-FMCOMMS1-EBZ board I2C-SPI bridge driver
3 *
4 * Copyright 2012 Analog Devices Inc.
5 * Author: Lars-Peter Clausen <lars@metafoo.de>
6 *
7 * Licensed under the GPL-2 or later.
8 */
9
10#include <linux/kernel.h>
11#include <linux/module.h>
12#include <linux/delay.h>
13#include <linux/i2c.h>
14#include <linux/spi/spi.h>
15#include <asm/unaligned.h>
16
17#define SPI_XCOMM_SETTINGS_LEN_OFFSET		10
18#define SPI_XCOMM_SETTINGS_3WIRE		BIT(6)
19#define SPI_XCOMM_SETTINGS_CS_HIGH		BIT(5)
20#define SPI_XCOMM_SETTINGS_SAMPLE_END		BIT(4)
21#define SPI_XCOMM_SETTINGS_CPHA			BIT(3)
22#define SPI_XCOMM_SETTINGS_CPOL			BIT(2)
23#define SPI_XCOMM_SETTINGS_CLOCK_DIV_MASK	0x3
24#define SPI_XCOMM_SETTINGS_CLOCK_DIV_64		0x2
25#define SPI_XCOMM_SETTINGS_CLOCK_DIV_16		0x1
26#define SPI_XCOMM_SETTINGS_CLOCK_DIV_4		0x0
27
28#define SPI_XCOMM_CMD_UPDATE_CONFIG	0x03
29#define SPI_XCOMM_CMD_WRITE		0x04
30
31#define SPI_XCOMM_CLOCK 48000000
32
33struct spi_xcomm {
34	struct i2c_client *i2c;
35
36	uint16_t settings;
37	uint16_t chipselect;
38
39	unsigned int current_speed;
40
41	uint8_t buf[63];
42};
43
44static int spi_xcomm_sync_config(struct spi_xcomm *spi_xcomm, unsigned int len)
45{
46	uint16_t settings;
47	uint8_t *buf = spi_xcomm->buf;
48
49	settings = spi_xcomm->settings;
50	settings |= len << SPI_XCOMM_SETTINGS_LEN_OFFSET;
51
52	buf[0] = SPI_XCOMM_CMD_UPDATE_CONFIG;
53	put_unaligned_be16(settings, &buf[1]);
54	put_unaligned_be16(spi_xcomm->chipselect, &buf[3]);
55
56	return i2c_master_send(spi_xcomm->i2c, buf, 5);
57}
58
59static void spi_xcomm_chipselect(struct spi_xcomm *spi_xcomm,
60	struct spi_device *spi, int is_active)
61{
62	unsigned long cs = spi->chip_select;
63	uint16_t chipselect = spi_xcomm->chipselect;
64
65	if (is_active)
66		chipselect |= BIT(cs);
67	else
68		chipselect &= ~BIT(cs);
69
70	spi_xcomm->chipselect = chipselect;
71}
72
73static int spi_xcomm_setup_transfer(struct spi_xcomm *spi_xcomm,
74	struct spi_device *spi, struct spi_transfer *t, unsigned int *settings)
75{
76	if (t->len > 62)
77		return -EINVAL;
78
79	if (t->speed_hz != spi_xcomm->current_speed) {
80		unsigned int divider;
81
82		divider = DIV_ROUND_UP(SPI_XCOMM_CLOCK, t->speed_hz);
83		if (divider >= 64)
84			*settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_64;
85		else if (divider >= 16)
86			*settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_16;
87		else
88			*settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_4;
89
90		spi_xcomm->current_speed = t->speed_hz;
91	}
92
93	if (spi->mode & SPI_CPOL)
94		*settings |= SPI_XCOMM_SETTINGS_CPOL;
95	else
96		*settings &= ~SPI_XCOMM_SETTINGS_CPOL;
97
98	if (spi->mode & SPI_CPHA)
99		*settings &= ~SPI_XCOMM_SETTINGS_CPHA;
100	else
101		*settings |= SPI_XCOMM_SETTINGS_CPHA;
102
103	if (spi->mode & SPI_3WIRE)
104		*settings |= SPI_XCOMM_SETTINGS_3WIRE;
105	else
106		*settings &= ~SPI_XCOMM_SETTINGS_3WIRE;
107
108	return 0;
109}
110
111static int spi_xcomm_txrx_bufs(struct spi_xcomm *spi_xcomm,
112	struct spi_device *spi, struct spi_transfer *t)
113{
114	int ret;
115
116	if (t->tx_buf) {
117		spi_xcomm->buf[0] = SPI_XCOMM_CMD_WRITE;
118		memcpy(spi_xcomm->buf + 1, t->tx_buf, t->len);
119
120		ret = i2c_master_send(spi_xcomm->i2c, spi_xcomm->buf, t->len + 1);
121		if (ret < 0)
122			return ret;
123		else if (ret != t->len + 1)
124			return -EIO;
125	} else if (t->rx_buf) {
126		ret = i2c_master_recv(spi_xcomm->i2c, t->rx_buf, t->len);
127		if (ret < 0)
128			return ret;
129		else if (ret != t->len)
130			return -EIO;
131	}
132
133	return t->len;
134}
135
136static int spi_xcomm_transfer_one(struct spi_master *master,
137	struct spi_message *msg)
138{
139	struct spi_xcomm *spi_xcomm = spi_master_get_devdata(master);
140	unsigned int settings = spi_xcomm->settings;
141	struct spi_device *spi = msg->spi;
142	unsigned cs_change = 0;
143	struct spi_transfer *t;
144	bool is_first = true;
145	int status = 0;
146	bool is_last;
147
148	spi_xcomm_chipselect(spi_xcomm, spi, true);
149
150	list_for_each_entry(t, &msg->transfers, transfer_list) {
151
152		if (!t->tx_buf && !t->rx_buf && t->len) {
153			status = -EINVAL;
154			break;
155		}
156
157		status = spi_xcomm_setup_transfer(spi_xcomm, spi, t, &settings);
158		if (status < 0)
159			break;
160
161		is_last = list_is_last(&t->transfer_list, &msg->transfers);
162		cs_change = t->cs_change;
163
164		if (cs_change ^ is_last)
165			settings |= BIT(5);
166		else
167			settings &= ~BIT(5);
168
169		if (t->rx_buf) {
170			spi_xcomm->settings = settings;
171			status = spi_xcomm_sync_config(spi_xcomm, t->len);
172			if (status < 0)
173				break;
174		} else if (settings != spi_xcomm->settings || is_first) {
175			spi_xcomm->settings = settings;
176			status = spi_xcomm_sync_config(spi_xcomm, 0);
177			if (status < 0)
178				break;
179		}
180
181		if (t->len) {
182			status = spi_xcomm_txrx_bufs(spi_xcomm, spi, t);
183
184			if (status < 0)
185				break;
186
187			if (status > 0)
188				msg->actual_length += status;
189		}
190		status = 0;
191
192		if (t->delay_usecs)
193			udelay(t->delay_usecs);
194
195		is_first = false;
196	}
197
198	if (status != 0 || !cs_change)
199		spi_xcomm_chipselect(spi_xcomm, spi, false);
200
201	msg->status = status;
202	spi_finalize_current_message(master);
203
204	return status;
205}
206
207static int spi_xcomm_probe(struct i2c_client *i2c,
208	const struct i2c_device_id *id)
209{
210	struct spi_xcomm *spi_xcomm;
211	struct spi_master *master;
212	int ret;
213
214	master = spi_alloc_master(&i2c->dev, sizeof(*spi_xcomm));
215	if (!master)
216		return -ENOMEM;
217
218	spi_xcomm = spi_master_get_devdata(master);
219	spi_xcomm->i2c = i2c;
220
221	master->num_chipselect = 16;
222	master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_3WIRE;
223	master->bits_per_word_mask = SPI_BPW_MASK(8);
224	master->flags = SPI_MASTER_HALF_DUPLEX;
225	master->transfer_one_message = spi_xcomm_transfer_one;
226	master->dev.of_node = i2c->dev.of_node;
227	i2c_set_clientdata(i2c, master);
228
229	ret = devm_spi_register_master(&i2c->dev, master);
230	if (ret < 0)
231		spi_master_put(master);
232
233	return ret;
234}
235
236static const struct i2c_device_id spi_xcomm_ids[] = {
237	{ "spi-xcomm" },
238	{ },
239};
240MODULE_DEVICE_TABLE(i2c, spi_xcomm_ids);
241
242static struct i2c_driver spi_xcomm_driver = {
243	.driver = {
244		.name	= "spi-xcomm",
245	},
246	.id_table	= spi_xcomm_ids,
247	.probe		= spi_xcomm_probe,
248};
249module_i2c_driver(spi_xcomm_driver);
250
251MODULE_LICENSE("GPL");
252MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
253MODULE_DESCRIPTION("Analog Devices AD-FMCOMMS1-EBZ board I2C-SPI bridge driver");
254