xref: /openbmc/linux/drivers/spi/spi-xcomm.c (revision 7a2b552c)
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 
32 struct 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 
spi_xcomm_sync_config(struct spi_xcomm * spi_xcomm,unsigned int len)43 static 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 
spi_xcomm_chipselect(struct spi_xcomm * spi_xcomm,struct spi_device * spi,int is_active)58 static 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 
spi_xcomm_setup_transfer(struct spi_xcomm * spi_xcomm,struct spi_device * spi,struct spi_transfer * t,unsigned int * settings)72 static 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 
spi_xcomm_txrx_bufs(struct spi_xcomm * spi_xcomm,struct spi_device * spi,struct spi_transfer * t)110 static 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 
spi_xcomm_transfer_one(struct spi_master * master,struct spi_message * msg)135 static int spi_xcomm_transfer_one(struct spi_master *master,
136 	struct spi_message *msg)
137 {
138 	struct spi_xcomm *spi_xcomm = spi_master_get_devdata(master);
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(master);
201 
202 	return status;
203 }
204 
spi_xcomm_probe(struct i2c_client * i2c)205 static int spi_xcomm_probe(struct i2c_client *i2c)
206 {
207 	struct spi_xcomm *spi_xcomm;
208 	struct spi_master *master;
209 	int ret;
210 
211 	master = spi_alloc_master(&i2c->dev, sizeof(*spi_xcomm));
212 	if (!master)
213 		return -ENOMEM;
214 
215 	spi_xcomm = spi_master_get_devdata(master);
216 	spi_xcomm->i2c = i2c;
217 
218 	master->num_chipselect = 16;
219 	master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_3WIRE;
220 	master->bits_per_word_mask = SPI_BPW_MASK(8);
221 	master->flags = SPI_CONTROLLER_HALF_DUPLEX;
222 	master->transfer_one_message = spi_xcomm_transfer_one;
223 	master->dev.of_node = i2c->dev.of_node;
224 	i2c_set_clientdata(i2c, master);
225 
226 	ret = devm_spi_register_master(&i2c->dev, master);
227 	if (ret < 0)
228 		spi_master_put(master);
229 
230 	return ret;
231 }
232 
233 static const struct i2c_device_id spi_xcomm_ids[] = {
234 	{ "spi-xcomm" },
235 	{ },
236 };
237 MODULE_DEVICE_TABLE(i2c, spi_xcomm_ids);
238 
239 static 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 };
246 module_i2c_driver(spi_xcomm_driver);
247 
248 MODULE_LICENSE("GPL");
249 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
250 MODULE_DESCRIPTION("Analog Devices AD-FMCOMMS1-EBZ board I2C-SPI bridge driver");
251