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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 <[email protected]>
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/gpio/driver.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 #define SPI_XCOMM_CMD_GPIO_SET          0x05
31
32 #define SPI_XCOMM_CLOCK 48000000
33
34 struct spi_xcomm {
35         struct i2c_client *i2c;
36
37         struct gpio_chip gc;
38
39         u16 settings;
40         u16 chipselect;
41
42         unsigned int current_speed;
43
44         u8 buf[63];
45 };
46
47 static void spi_xcomm_gpio_set_value(struct gpio_chip *chip,
48                                      unsigned int offset, int val)
49 {
50         struct spi_xcomm *spi_xcomm = gpiochip_get_data(chip);
51         unsigned char buf[2];
52
53         buf[0] = SPI_XCOMM_CMD_GPIO_SET;
54         buf[1] = !!val;
55
56         i2c_master_send(spi_xcomm->i2c, buf, 2);
57 }
58
59 static int spi_xcomm_gpio_get_direction(struct gpio_chip *chip,
60                                         unsigned int offset)
61 {
62         return GPIO_LINE_DIRECTION_OUT;
63 }
64
65 static int spi_xcomm_gpio_add(struct spi_xcomm *spi_xcomm)
66 {
67         struct device *dev = &spi_xcomm->i2c->dev;
68
69         if (!IS_ENABLED(CONFIG_GPIOLIB))
70                 return 0;
71
72         spi_xcomm->gc.get_direction = spi_xcomm_gpio_get_direction;
73         spi_xcomm->gc.set = spi_xcomm_gpio_set_value;
74         spi_xcomm->gc.can_sleep = 1;
75         spi_xcomm->gc.base = -1;
76         spi_xcomm->gc.ngpio = 1;
77         spi_xcomm->gc.label = spi_xcomm->i2c->name;
78         spi_xcomm->gc.owner = THIS_MODULE;
79
80         return devm_gpiochip_add_data(dev, &spi_xcomm->gc, spi_xcomm);
81 }
82
83 static int spi_xcomm_sync_config(struct spi_xcomm *spi_xcomm, unsigned int len)
84 {
85         u16 settings;
86         u8 *buf = spi_xcomm->buf;
87
88         settings = spi_xcomm->settings;
89         settings |= len << SPI_XCOMM_SETTINGS_LEN_OFFSET;
90
91         buf[0] = SPI_XCOMM_CMD_UPDATE_CONFIG;
92         put_unaligned_be16(settings, &buf[1]);
93         put_unaligned_be16(spi_xcomm->chipselect, &buf[3]);
94
95         return i2c_master_send(spi_xcomm->i2c, buf, 5);
96 }
97
98 static void spi_xcomm_chipselect(struct spi_xcomm *spi_xcomm,
99                                  struct spi_device *spi, int is_active)
100 {
101         unsigned long cs = spi_get_chipselect(spi, 0);
102         u16 chipselect = spi_xcomm->chipselect;
103
104         if (is_active)
105                 chipselect |= BIT(cs);
106         else
107                 chipselect &= ~BIT(cs);
108
109         spi_xcomm->chipselect = chipselect;
110 }
111
112 static int spi_xcomm_setup_transfer(struct spi_xcomm *spi_xcomm,
113                                     struct spi_device *spi, struct spi_transfer *t,
114                                     unsigned int *settings)
115 {
116         if (t->len > 62)
117                 return -EINVAL;
118
119         if (t->speed_hz != spi_xcomm->current_speed) {
120                 unsigned int divider;
121
122                 divider = DIV_ROUND_UP(SPI_XCOMM_CLOCK, t->speed_hz);
123                 if (divider >= 64)
124                         *settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_64;
125                 else if (divider >= 16)
126                         *settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_16;
127                 else
128                         *settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_4;
129
130                 spi_xcomm->current_speed = t->speed_hz;
131         }
132
133         if (spi->mode & SPI_CPOL)
134                 *settings |= SPI_XCOMM_SETTINGS_CPOL;
135         else
136                 *settings &= ~SPI_XCOMM_SETTINGS_CPOL;
137
138         if (spi->mode & SPI_CPHA)
139                 *settings &= ~SPI_XCOMM_SETTINGS_CPHA;
140         else
141                 *settings |= SPI_XCOMM_SETTINGS_CPHA;
142
143         if (spi->mode & SPI_3WIRE)
144                 *settings |= SPI_XCOMM_SETTINGS_3WIRE;
145         else
146                 *settings &= ~SPI_XCOMM_SETTINGS_3WIRE;
147
148         return 0;
149 }
150
151 static int spi_xcomm_txrx_bufs(struct spi_xcomm *spi_xcomm,
152                                struct spi_device *spi, struct spi_transfer *t)
153 {
154         int ret;
155
156         if (t->tx_buf) {
157                 spi_xcomm->buf[0] = SPI_XCOMM_CMD_WRITE;
158                 memcpy(spi_xcomm->buf + 1, t->tx_buf, t->len);
159
160                 ret = i2c_master_send(spi_xcomm->i2c, spi_xcomm->buf, t->len + 1);
161                 if (ret < 0)
162                         return ret;
163                 if (ret != t->len + 1)
164                         return -EIO;
165         } else if (t->rx_buf) {
166                 ret = i2c_master_recv(spi_xcomm->i2c, t->rx_buf, t->len);
167                 if (ret < 0)
168                         return ret;
169                 if (ret != t->len)
170                         return -EIO;
171         }
172
173         return t->len;
174 }
175
176 static int spi_xcomm_transfer_one(struct spi_controller *host,
177                                   struct spi_message *msg)
178 {
179         struct spi_xcomm *spi_xcomm = spi_controller_get_devdata(host);
180         unsigned int settings = spi_xcomm->settings;
181         struct spi_device *spi = msg->spi;
182         unsigned int cs_change = 0;
183         struct spi_transfer *t;
184         bool is_first = true;
185         int status = 0;
186         bool is_last;
187
188         spi_xcomm_chipselect(spi_xcomm, spi, true);
189
190         list_for_each_entry(t, &msg->transfers, transfer_list) {
191                 if (!t->tx_buf && !t->rx_buf && t->len) {
192                         status = -EINVAL;
193                         break;
194                 }
195
196                 status = spi_xcomm_setup_transfer(spi_xcomm, spi, t, &settings);
197                 if (status < 0)
198                         break;
199
200                 is_last = list_is_last(&t->transfer_list, &msg->transfers);
201                 cs_change = t->cs_change;
202
203                 if (cs_change ^ is_last)
204                         settings |= BIT(5);
205                 else
206                         settings &= ~BIT(5);
207
208                 if (t->rx_buf) {
209                         spi_xcomm->settings = settings;
210                         status = spi_xcomm_sync_config(spi_xcomm, t->len);
211                         if (status < 0)
212                                 break;
213                 } else if (settings != spi_xcomm->settings || is_first) {
214                         spi_xcomm->settings = settings;
215                         status = spi_xcomm_sync_config(spi_xcomm, 0);
216                         if (status < 0)
217                                 break;
218                 }
219
220                 if (t->len) {
221                         status = spi_xcomm_txrx_bufs(spi_xcomm, spi, t);
222
223                         if (status < 0)
224                                 break;
225
226                         if (status > 0)
227                                 msg->actual_length += status;
228                 }
229                 status = 0;
230
231                 spi_transfer_delay_exec(t);
232
233                 is_first = false;
234         }
235
236         if (status != 0 || !cs_change)
237                 spi_xcomm_chipselect(spi_xcomm, spi, false);
238
239         msg->status = status;
240         spi_finalize_current_message(host);
241
242         return status;
243 }
244
245 static int spi_xcomm_probe(struct i2c_client *i2c)
246 {
247         struct spi_xcomm *spi_xcomm;
248         struct spi_controller *host;
249         int ret;
250
251         host = devm_spi_alloc_host(&i2c->dev, sizeof(*spi_xcomm));
252         if (!host)
253                 return -ENOMEM;
254
255         spi_xcomm = spi_controller_get_devdata(host);
256         spi_xcomm->i2c = i2c;
257
258         host->num_chipselect = 16;
259         host->mode_bits = SPI_CPHA | SPI_CPOL | SPI_3WIRE;
260         host->bits_per_word_mask = SPI_BPW_MASK(8);
261         host->flags = SPI_CONTROLLER_HALF_DUPLEX;
262         host->transfer_one_message = spi_xcomm_transfer_one;
263         host->dev.of_node = i2c->dev.of_node;
264
265         ret = devm_spi_register_controller(&i2c->dev, host);
266         if (ret < 0)
267                 return ret;
268
269         return spi_xcomm_gpio_add(spi_xcomm);
270 }
271
272 static const struct i2c_device_id spi_xcomm_ids[] = {
273         { "spi-xcomm" },
274         { },
275 };
276 MODULE_DEVICE_TABLE(i2c, spi_xcomm_ids);
277
278 static struct i2c_driver spi_xcomm_driver = {
279         .driver = {
280                 .name   = "spi-xcomm",
281         },
282         .id_table       = spi_xcomm_ids,
283         .probe          = spi_xcomm_probe,
284 };
285 module_i2c_driver(spi_xcomm_driver);
286
287 MODULE_LICENSE("GPL");
288 MODULE_AUTHOR("Lars-Peter Clausen <[email protected]>");
289 MODULE_DESCRIPTION("Analog Devices AD-FMCOMMS1-EBZ board I2C-SPI bridge driver");
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