1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Copyright (C) 2010-2013 Bluecherry, LLC <https://www.bluecherrydvr.com>
4  *
5  * Original author:
6  * Ben Collins <bcollins@ubuntu.com>
7  *
8  * Additional work by:
9  * John Brooks <john.brooks@bluecherry.net>
10  */
11 
12 /* XXX: The SOLO6x10 i2c does not have separate interrupts for each i2c
13  * channel. The bus can only handle one i2c event at a time. The below handles
14  * this all wrong. We should be using the status registers to see if the bus
15  * is in use, and have a global lock to check the status register. Also,
16  * the bulk of the work should be handled out-of-interrupt. The ugly loops
17  * that occur during interrupt scare me. The ISR should merely signal
18  * thread context, ACK the interrupt, and move on. -- BenC */
19 
20 #include <linux/kernel.h>
21 #include <linux/sched/signal.h>
22 
23 #include "solo6x10.h"
24 
25 u8 solo_i2c_readbyte(struct solo_dev *solo_dev, int id, u8 addr, u8 off)
26 {
27 	struct i2c_msg msgs[2];
28 	u8 data;
29 
30 	msgs[0].flags = 0;
31 	msgs[0].addr = addr;
32 	msgs[0].len = 1;
33 	msgs[0].buf = &off;
34 
35 	msgs[1].flags = I2C_M_RD;
36 	msgs[1].addr = addr;
37 	msgs[1].len = 1;
38 	msgs[1].buf = &data;
39 
40 	i2c_transfer(&solo_dev->i2c_adap[id], msgs, 2);
41 
42 	return data;
43 }
44 
45 void solo_i2c_writebyte(struct solo_dev *solo_dev, int id, u8 addr,
46 			u8 off, u8 data)
47 {
48 	struct i2c_msg msgs;
49 	u8 buf[2];
50 
51 	buf[0] = off;
52 	buf[1] = data;
53 	msgs.flags = 0;
54 	msgs.addr = addr;
55 	msgs.len = 2;
56 	msgs.buf = buf;
57 
58 	i2c_transfer(&solo_dev->i2c_adap[id], &msgs, 1);
59 }
60 
61 static void solo_i2c_flush(struct solo_dev *solo_dev, int wr)
62 {
63 	u32 ctrl;
64 
65 	ctrl = SOLO_IIC_CH_SET(solo_dev->i2c_id);
66 
67 	if (solo_dev->i2c_state == IIC_STATE_START)
68 		ctrl |= SOLO_IIC_START;
69 
70 	if (wr) {
71 		ctrl |= SOLO_IIC_WRITE;
72 	} else {
73 		ctrl |= SOLO_IIC_READ;
74 		if (!(solo_dev->i2c_msg->flags & I2C_M_NO_RD_ACK))
75 			ctrl |= SOLO_IIC_ACK_EN;
76 	}
77 
78 	if (solo_dev->i2c_msg_ptr == solo_dev->i2c_msg->len)
79 		ctrl |= SOLO_IIC_STOP;
80 
81 	solo_reg_write(solo_dev, SOLO_IIC_CTRL, ctrl);
82 }
83 
84 static void solo_i2c_start(struct solo_dev *solo_dev)
85 {
86 	u32 addr = solo_dev->i2c_msg->addr << 1;
87 
88 	if (solo_dev->i2c_msg->flags & I2C_M_RD)
89 		addr |= 1;
90 
91 	solo_dev->i2c_state = IIC_STATE_START;
92 	solo_reg_write(solo_dev, SOLO_IIC_TXD, addr);
93 	solo_i2c_flush(solo_dev, 1);
94 }
95 
96 static void solo_i2c_stop(struct solo_dev *solo_dev)
97 {
98 	solo_irq_off(solo_dev, SOLO_IRQ_IIC);
99 	solo_reg_write(solo_dev, SOLO_IIC_CTRL, 0);
100 	solo_dev->i2c_state = IIC_STATE_STOP;
101 	wake_up(&solo_dev->i2c_wait);
102 }
103 
104 static int solo_i2c_handle_read(struct solo_dev *solo_dev)
105 {
106 prepare_read:
107 	if (solo_dev->i2c_msg_ptr != solo_dev->i2c_msg->len) {
108 		solo_i2c_flush(solo_dev, 0);
109 		return 0;
110 	}
111 
112 	solo_dev->i2c_msg_ptr = 0;
113 	solo_dev->i2c_msg++;
114 	solo_dev->i2c_msg_num--;
115 
116 	if (solo_dev->i2c_msg_num == 0) {
117 		solo_i2c_stop(solo_dev);
118 		return 0;
119 	}
120 
121 	if (!(solo_dev->i2c_msg->flags & I2C_M_NOSTART)) {
122 		solo_i2c_start(solo_dev);
123 	} else {
124 		if (solo_dev->i2c_msg->flags & I2C_M_RD)
125 			goto prepare_read;
126 		else
127 			solo_i2c_stop(solo_dev);
128 	}
129 
130 	return 0;
131 }
132 
133 static int solo_i2c_handle_write(struct solo_dev *solo_dev)
134 {
135 retry_write:
136 	if (solo_dev->i2c_msg_ptr != solo_dev->i2c_msg->len) {
137 		solo_reg_write(solo_dev, SOLO_IIC_TXD,
138 			       solo_dev->i2c_msg->buf[solo_dev->i2c_msg_ptr]);
139 		solo_dev->i2c_msg_ptr++;
140 		solo_i2c_flush(solo_dev, 1);
141 		return 0;
142 	}
143 
144 	solo_dev->i2c_msg_ptr = 0;
145 	solo_dev->i2c_msg++;
146 	solo_dev->i2c_msg_num--;
147 
148 	if (solo_dev->i2c_msg_num == 0) {
149 		solo_i2c_stop(solo_dev);
150 		return 0;
151 	}
152 
153 	if (!(solo_dev->i2c_msg->flags & I2C_M_NOSTART)) {
154 		solo_i2c_start(solo_dev);
155 	} else {
156 		if (solo_dev->i2c_msg->flags & I2C_M_RD)
157 			solo_i2c_stop(solo_dev);
158 		else
159 			goto retry_write;
160 	}
161 
162 	return 0;
163 }
164 
165 int solo_i2c_isr(struct solo_dev *solo_dev)
166 {
167 	u32 status = solo_reg_read(solo_dev, SOLO_IIC_CTRL);
168 	int ret = -EINVAL;
169 
170 
171 	if (CHK_FLAGS(status, SOLO_IIC_STATE_TRNS | SOLO_IIC_STATE_SIG_ERR)
172 	    || solo_dev->i2c_id < 0) {
173 		solo_i2c_stop(solo_dev);
174 		return -ENXIO;
175 	}
176 
177 	switch (solo_dev->i2c_state) {
178 	case IIC_STATE_START:
179 		if (solo_dev->i2c_msg->flags & I2C_M_RD) {
180 			solo_dev->i2c_state = IIC_STATE_READ;
181 			ret = solo_i2c_handle_read(solo_dev);
182 			break;
183 		}
184 
185 		solo_dev->i2c_state = IIC_STATE_WRITE;
186 		fallthrough;
187 	case IIC_STATE_WRITE:
188 		ret = solo_i2c_handle_write(solo_dev);
189 		break;
190 
191 	case IIC_STATE_READ:
192 		solo_dev->i2c_msg->buf[solo_dev->i2c_msg_ptr] =
193 			solo_reg_read(solo_dev, SOLO_IIC_RXD);
194 		solo_dev->i2c_msg_ptr++;
195 
196 		ret = solo_i2c_handle_read(solo_dev);
197 		break;
198 
199 	default:
200 		solo_i2c_stop(solo_dev);
201 	}
202 
203 	return ret;
204 }
205 
206 static int solo_i2c_master_xfer(struct i2c_adapter *adap,
207 				struct i2c_msg msgs[], int num)
208 {
209 	struct solo_dev *solo_dev = adap->algo_data;
210 	unsigned long timeout;
211 	int ret;
212 	int i;
213 	DEFINE_WAIT(wait);
214 
215 	for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
216 		if (&solo_dev->i2c_adap[i] == adap)
217 			break;
218 	}
219 
220 	if (i == SOLO_I2C_ADAPTERS)
221 		return num; /* XXX Right return value for failure? */
222 
223 	mutex_lock(&solo_dev->i2c_mutex);
224 	solo_dev->i2c_id = i;
225 	solo_dev->i2c_msg = msgs;
226 	solo_dev->i2c_msg_num = num;
227 	solo_dev->i2c_msg_ptr = 0;
228 
229 	solo_reg_write(solo_dev, SOLO_IIC_CTRL, 0);
230 	solo_irq_on(solo_dev, SOLO_IRQ_IIC);
231 	solo_i2c_start(solo_dev);
232 
233 	timeout = HZ / 2;
234 
235 	for (;;) {
236 		prepare_to_wait(&solo_dev->i2c_wait, &wait,
237 				TASK_INTERRUPTIBLE);
238 
239 		if (solo_dev->i2c_state == IIC_STATE_STOP)
240 			break;
241 
242 		timeout = schedule_timeout(timeout);
243 		if (!timeout)
244 			break;
245 
246 		if (signal_pending(current))
247 			break;
248 	}
249 
250 	finish_wait(&solo_dev->i2c_wait, &wait);
251 	ret = num - solo_dev->i2c_msg_num;
252 	solo_dev->i2c_state = IIC_STATE_IDLE;
253 	solo_dev->i2c_id = -1;
254 
255 	mutex_unlock(&solo_dev->i2c_mutex);
256 
257 	return ret;
258 }
259 
260 static u32 solo_i2c_functionality(struct i2c_adapter *adap)
261 {
262 	return I2C_FUNC_I2C;
263 }
264 
265 static const struct i2c_algorithm solo_i2c_algo = {
266 	.master_xfer	= solo_i2c_master_xfer,
267 	.functionality	= solo_i2c_functionality,
268 };
269 
270 int solo_i2c_init(struct solo_dev *solo_dev)
271 {
272 	int i;
273 	int ret;
274 
275 	solo_reg_write(solo_dev, SOLO_IIC_CFG,
276 		       SOLO_IIC_PRESCALE(8) | SOLO_IIC_ENABLE);
277 
278 	solo_dev->i2c_id = -1;
279 	solo_dev->i2c_state = IIC_STATE_IDLE;
280 	init_waitqueue_head(&solo_dev->i2c_wait);
281 	mutex_init(&solo_dev->i2c_mutex);
282 
283 	for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
284 		struct i2c_adapter *adap = &solo_dev->i2c_adap[i];
285 
286 		snprintf(adap->name, I2C_NAME_SIZE, "%s I2C %d",
287 			 SOLO6X10_NAME, i);
288 		adap->algo = &solo_i2c_algo;
289 		adap->algo_data = solo_dev;
290 		adap->retries = 1;
291 		adap->dev.parent = &solo_dev->pdev->dev;
292 
293 		ret = i2c_add_adapter(adap);
294 		if (ret) {
295 			adap->algo_data = NULL;
296 			break;
297 		}
298 	}
299 
300 	if (ret) {
301 		for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
302 			if (!solo_dev->i2c_adap[i].algo_data)
303 				break;
304 			i2c_del_adapter(&solo_dev->i2c_adap[i]);
305 			solo_dev->i2c_adap[i].algo_data = NULL;
306 		}
307 		return ret;
308 	}
309 
310 	return 0;
311 }
312 
313 void solo_i2c_exit(struct solo_dev *solo_dev)
314 {
315 	int i;
316 
317 	for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
318 		if (!solo_dev->i2c_adap[i].algo_data)
319 			continue;
320 		i2c_del_adapter(&solo_dev->i2c_adap[i]);
321 		solo_dev->i2c_adap[i].algo_data = NULL;
322 	}
323 }
324