xref: /linux/drivers/spi/spi-xcomm.c (revision b889fcf63cb62e7fdb7816565e28f44dbe4a76a5)
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/init.h>
12 #include <linux/module.h>
13 #include <linux/delay.h>
14 #include <linux/i2c.h>
15 #include <linux/spi/spi.h>
16 #include <asm/unaligned.h>
17 
18 #define SPI_XCOMM_SETTINGS_LEN_OFFSET		10
19 #define SPI_XCOMM_SETTINGS_3WIRE		BIT(6)
20 #define SPI_XCOMM_SETTINGS_CS_HIGH		BIT(5)
21 #define SPI_XCOMM_SETTINGS_SAMPLE_END		BIT(4)
22 #define SPI_XCOMM_SETTINGS_CPHA			BIT(3)
23 #define SPI_XCOMM_SETTINGS_CPOL			BIT(2)
24 #define SPI_XCOMM_SETTINGS_CLOCK_DIV_MASK	0x3
25 #define SPI_XCOMM_SETTINGS_CLOCK_DIV_64		0x2
26 #define SPI_XCOMM_SETTINGS_CLOCK_DIV_16		0x1
27 #define SPI_XCOMM_SETTINGS_CLOCK_DIV_4		0x0
28 
29 #define SPI_XCOMM_CMD_UPDATE_CONFIG	0x03
30 #define SPI_XCOMM_CMD_WRITE		0x04
31 
32 #define SPI_XCOMM_CLOCK 48000000
33 
34 struct spi_xcomm {
35 	struct i2c_client *i2c;
36 
37 	uint16_t settings;
38 	uint16_t chipselect;
39 
40 	unsigned int current_speed;
41 
42 	uint8_t buf[63];
43 };
44 
45 static int spi_xcomm_sync_config(struct spi_xcomm *spi_xcomm, unsigned int len)
46 {
47 	uint16_t settings;
48 	uint8_t *buf = spi_xcomm->buf;
49 
50 	settings = spi_xcomm->settings;
51 	settings |= len << SPI_XCOMM_SETTINGS_LEN_OFFSET;
52 
53 	buf[0] = SPI_XCOMM_CMD_UPDATE_CONFIG;
54 	put_unaligned_be16(settings, &buf[1]);
55 	put_unaligned_be16(spi_xcomm->chipselect, &buf[3]);
56 
57 	return i2c_master_send(spi_xcomm->i2c, buf, 5);
58 }
59 
60 static void spi_xcomm_chipselect(struct spi_xcomm *spi_xcomm,
61 	struct spi_device *spi, int is_active)
62 {
63 	unsigned long cs = spi->chip_select;
64 	uint16_t chipselect = spi_xcomm->chipselect;
65 
66 	if (is_active)
67 		chipselect |= BIT(cs);
68 	else
69 		chipselect &= ~BIT(cs);
70 
71 	spi_xcomm->chipselect = chipselect;
72 }
73 
74 static int spi_xcomm_setup_transfer(struct spi_xcomm *spi_xcomm,
75 	struct spi_device *spi, struct spi_transfer *t, unsigned int *settings)
76 {
77 	unsigned int speed;
78 
79 	if ((t->bits_per_word && t->bits_per_word != 8) || t->len > 62)
80 		return -EINVAL;
81 
82 	speed = t->speed_hz ? t->speed_hz : spi->max_speed_hz;
83 
84 	if (speed != spi_xcomm->current_speed) {
85 		unsigned int divider = DIV_ROUND_UP(SPI_XCOMM_CLOCK, speed);
86 		if (divider >= 64)
87 			*settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_64;
88 		else if (divider >= 16)
89 			*settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_16;
90 		else
91 			*settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_4;
92 
93 		spi_xcomm->current_speed = speed;
94 	}
95 
96 	if (spi->mode & SPI_CPOL)
97 		*settings |= SPI_XCOMM_SETTINGS_CPOL;
98 	else
99 		*settings &= ~SPI_XCOMM_SETTINGS_CPOL;
100 
101 	if (spi->mode & SPI_CPHA)
102 		*settings &= ~SPI_XCOMM_SETTINGS_CPHA;
103 	else
104 		*settings |= SPI_XCOMM_SETTINGS_CPHA;
105 
106 	if (spi->mode & SPI_3WIRE)
107 		*settings |= SPI_XCOMM_SETTINGS_3WIRE;
108 	else
109 		*settings &= ~SPI_XCOMM_SETTINGS_3WIRE;
110 
111 	return 0;
112 }
113 
114 static int spi_xcomm_txrx_bufs(struct spi_xcomm *spi_xcomm,
115 	struct spi_device *spi, struct spi_transfer *t)
116 {
117 	int ret;
118 
119 	if (t->tx_buf) {
120 		spi_xcomm->buf[0] = SPI_XCOMM_CMD_WRITE;
121 		memcpy(spi_xcomm->buf + 1, t->tx_buf, t->len);
122 
123 		ret = i2c_master_send(spi_xcomm->i2c, spi_xcomm->buf, t->len + 1);
124 		if (ret < 0)
125 			return ret;
126 		else if (ret != t->len + 1)
127 			return -EIO;
128 	} else if (t->rx_buf) {
129 		ret = i2c_master_recv(spi_xcomm->i2c, t->rx_buf, t->len);
130 		if (ret < 0)
131 			return ret;
132 		else if (ret != t->len)
133 			return -EIO;
134 	}
135 
136 	return t->len;
137 }
138 
139 static int spi_xcomm_transfer_one(struct spi_master *master,
140 	struct spi_message *msg)
141 {
142 	struct spi_xcomm *spi_xcomm = spi_master_get_devdata(master);
143 	unsigned int settings = spi_xcomm->settings;
144 	struct spi_device *spi = msg->spi;
145 	unsigned cs_change = 0;
146 	struct spi_transfer *t;
147 	bool is_first = true;
148 	int status = 0;
149 	bool is_last;
150 
151 	is_first = true;
152 
153 	spi_xcomm_chipselect(spi_xcomm, spi, true);
154 
155 	list_for_each_entry(t, &msg->transfers, transfer_list) {
156 
157 		if (!t->tx_buf && !t->rx_buf && t->len) {
158 			status = -EINVAL;
159 			break;
160 		}
161 
162 		status = spi_xcomm_setup_transfer(spi_xcomm, spi, t, &settings);
163 		if (status < 0)
164 			break;
165 
166 		is_last = list_is_last(&t->transfer_list, &msg->transfers);
167 		cs_change = t->cs_change;
168 
169 		if (cs_change ^ is_last)
170 			settings |= BIT(5);
171 		else
172 			settings &= ~BIT(5);
173 
174 		if (t->rx_buf) {
175 			spi_xcomm->settings = settings;
176 			status = spi_xcomm_sync_config(spi_xcomm, t->len);
177 			if (status < 0)
178 				break;
179 		} else if (settings != spi_xcomm->settings || is_first) {
180 			spi_xcomm->settings = settings;
181 			status = spi_xcomm_sync_config(spi_xcomm, 0);
182 			if (status < 0)
183 				break;
184 		}
185 
186 		if (t->len) {
187 			status = spi_xcomm_txrx_bufs(spi_xcomm, spi, t);
188 
189 			if (status < 0)
190 				break;
191 
192 			if (status > 0)
193 				msg->actual_length += status;
194 		}
195 		status = 0;
196 
197 		if (t->delay_usecs)
198 			udelay(t->delay_usecs);
199 
200 		is_first = false;
201 	}
202 
203 	if (status != 0 || !cs_change)
204 		spi_xcomm_chipselect(spi_xcomm, spi, false);
205 
206 	msg->status = status;
207 	spi_finalize_current_message(master);
208 
209 	return status;
210 }
211 
212 static int spi_xcomm_setup(struct spi_device *spi)
213 {
214 	if (spi->bits_per_word != 8)
215 		return -EINVAL;
216 
217 	return 0;
218 }
219 
220 static int spi_xcomm_probe(struct i2c_client *i2c,
221 	const struct i2c_device_id *id)
222 {
223 	struct spi_xcomm *spi_xcomm;
224 	struct spi_master *master;
225 	int ret;
226 
227 	master = spi_alloc_master(&i2c->dev, sizeof(*spi_xcomm));
228 	if (!master)
229 		return -ENOMEM;
230 
231 	spi_xcomm = spi_master_get_devdata(master);
232 	spi_xcomm->i2c = i2c;
233 
234 	master->num_chipselect = 16;
235 	master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_3WIRE;
236 	master->flags = SPI_MASTER_HALF_DUPLEX;
237 	master->setup = spi_xcomm_setup;
238 	master->transfer_one_message = spi_xcomm_transfer_one;
239 	master->dev.of_node = i2c->dev.of_node;
240 	i2c_set_clientdata(i2c, master);
241 
242 	ret = spi_register_master(master);
243 	if (ret < 0)
244 		spi_master_put(master);
245 
246 	return ret;
247 }
248 
249 static int spi_xcomm_remove(struct i2c_client *i2c)
250 {
251 	struct spi_master *master = i2c_get_clientdata(i2c);
252 
253 	spi_unregister_master(master);
254 
255 	return 0;
256 }
257 
258 static const struct i2c_device_id spi_xcomm_ids[] = {
259 	{ "spi-xcomm" },
260 	{ },
261 };
262 
263 static struct i2c_driver spi_xcomm_driver = {
264 	.driver = {
265 		.name	= "spi-xcomm",
266 		.owner	= THIS_MODULE,
267 	},
268 	.id_table	= spi_xcomm_ids,
269 	.probe		= spi_xcomm_probe,
270 	.remove		= spi_xcomm_remove,
271 };
272 module_i2c_driver(spi_xcomm_driver);
273 
274 MODULE_LICENSE("GPL");
275 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
276 MODULE_DESCRIPTION("Analog Devices AD-FMCOMMS1-EBZ board I2C-SPI bridge driver");
277