1 /*
2  * Copyright (C) 2010-2013 Bluecherry, LLC <http://www.bluecherrydvr.com>
3  *
4  * Original author:
5  * Ben Collins <bcollins@ubuntu.com>
6  *
7  * Additional work by:
8  * John Brooks <john.brooks@bluecherry.net>
9  *
10  * This program is free software; you can redistribute it and/or modify
11  * it under the terms of the GNU General Public License as published by
12  * the Free Software Foundation; either version 2 of the License, or
13  * (at your option) any later version.
14  *
15  * This program is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18  * GNU General Public License for more details.
19  */
20 
21 /* XXX: The SOLO6x10 i2c does not have separate interrupts for each i2c
22  * channel. The bus can only handle one i2c event at a time. The below handles
23  * this all wrong. We should be using the status registers to see if the bus
24  * is in use, and have a global lock to check the status register. Also,
25  * the bulk of the work should be handled out-of-interrupt. The ugly loops
26  * that occur during interrupt scare me. The ISR should merely signal
27  * thread context, ACK the interrupt, and move on. -- BenC */
28 
29 #include <linux/kernel.h>
30 #include <linux/sched/signal.h>
31 
32 #include "solo6x10.h"
33 
34 u8 solo_i2c_readbyte(struct solo_dev *solo_dev, int id, u8 addr, u8 off)
35 {
36 	struct i2c_msg msgs[2];
37 	u8 data;
38 
39 	msgs[0].flags = 0;
40 	msgs[0].addr = addr;
41 	msgs[0].len = 1;
42 	msgs[0].buf = &off;
43 
44 	msgs[1].flags = I2C_M_RD;
45 	msgs[1].addr = addr;
46 	msgs[1].len = 1;
47 	msgs[1].buf = &data;
48 
49 	i2c_transfer(&solo_dev->i2c_adap[id], msgs, 2);
50 
51 	return data;
52 }
53 
54 void solo_i2c_writebyte(struct solo_dev *solo_dev, int id, u8 addr,
55 			u8 off, u8 data)
56 {
57 	struct i2c_msg msgs;
58 	u8 buf[2];
59 
60 	buf[0] = off;
61 	buf[1] = data;
62 	msgs.flags = 0;
63 	msgs.addr = addr;
64 	msgs.len = 2;
65 	msgs.buf = buf;
66 
67 	i2c_transfer(&solo_dev->i2c_adap[id], &msgs, 1);
68 }
69 
70 static void solo_i2c_flush(struct solo_dev *solo_dev, int wr)
71 {
72 	u32 ctrl;
73 
74 	ctrl = SOLO_IIC_CH_SET(solo_dev->i2c_id);
75 
76 	if (solo_dev->i2c_state == IIC_STATE_START)
77 		ctrl |= SOLO_IIC_START;
78 
79 	if (wr) {
80 		ctrl |= SOLO_IIC_WRITE;
81 	} else {
82 		ctrl |= SOLO_IIC_READ;
83 		if (!(solo_dev->i2c_msg->flags & I2C_M_NO_RD_ACK))
84 			ctrl |= SOLO_IIC_ACK_EN;
85 	}
86 
87 	if (solo_dev->i2c_msg_ptr == solo_dev->i2c_msg->len)
88 		ctrl |= SOLO_IIC_STOP;
89 
90 	solo_reg_write(solo_dev, SOLO_IIC_CTRL, ctrl);
91 }
92 
93 static void solo_i2c_start(struct solo_dev *solo_dev)
94 {
95 	u32 addr = solo_dev->i2c_msg->addr << 1;
96 
97 	if (solo_dev->i2c_msg->flags & I2C_M_RD)
98 		addr |= 1;
99 
100 	solo_dev->i2c_state = IIC_STATE_START;
101 	solo_reg_write(solo_dev, SOLO_IIC_TXD, addr);
102 	solo_i2c_flush(solo_dev, 1);
103 }
104 
105 static void solo_i2c_stop(struct solo_dev *solo_dev)
106 {
107 	solo_irq_off(solo_dev, SOLO_IRQ_IIC);
108 	solo_reg_write(solo_dev, SOLO_IIC_CTRL, 0);
109 	solo_dev->i2c_state = IIC_STATE_STOP;
110 	wake_up(&solo_dev->i2c_wait);
111 }
112 
113 static int solo_i2c_handle_read(struct solo_dev *solo_dev)
114 {
115 prepare_read:
116 	if (solo_dev->i2c_msg_ptr != solo_dev->i2c_msg->len) {
117 		solo_i2c_flush(solo_dev, 0);
118 		return 0;
119 	}
120 
121 	solo_dev->i2c_msg_ptr = 0;
122 	solo_dev->i2c_msg++;
123 	solo_dev->i2c_msg_num--;
124 
125 	if (solo_dev->i2c_msg_num == 0) {
126 		solo_i2c_stop(solo_dev);
127 		return 0;
128 	}
129 
130 	if (!(solo_dev->i2c_msg->flags & I2C_M_NOSTART)) {
131 		solo_i2c_start(solo_dev);
132 	} else {
133 		if (solo_dev->i2c_msg->flags & I2C_M_RD)
134 			goto prepare_read;
135 		else
136 			solo_i2c_stop(solo_dev);
137 	}
138 
139 	return 0;
140 }
141 
142 static int solo_i2c_handle_write(struct solo_dev *solo_dev)
143 {
144 retry_write:
145 	if (solo_dev->i2c_msg_ptr != solo_dev->i2c_msg->len) {
146 		solo_reg_write(solo_dev, SOLO_IIC_TXD,
147 			       solo_dev->i2c_msg->buf[solo_dev->i2c_msg_ptr]);
148 		solo_dev->i2c_msg_ptr++;
149 		solo_i2c_flush(solo_dev, 1);
150 		return 0;
151 	}
152 
153 	solo_dev->i2c_msg_ptr = 0;
154 	solo_dev->i2c_msg++;
155 	solo_dev->i2c_msg_num--;
156 
157 	if (solo_dev->i2c_msg_num == 0) {
158 		solo_i2c_stop(solo_dev);
159 		return 0;
160 	}
161 
162 	if (!(solo_dev->i2c_msg->flags & I2C_M_NOSTART)) {
163 		solo_i2c_start(solo_dev);
164 	} else {
165 		if (solo_dev->i2c_msg->flags & I2C_M_RD)
166 			solo_i2c_stop(solo_dev);
167 		else
168 			goto retry_write;
169 	}
170 
171 	return 0;
172 }
173 
174 int solo_i2c_isr(struct solo_dev *solo_dev)
175 {
176 	u32 status = solo_reg_read(solo_dev, SOLO_IIC_CTRL);
177 	int ret = -EINVAL;
178 
179 
180 	if (CHK_FLAGS(status, SOLO_IIC_STATE_TRNS | SOLO_IIC_STATE_SIG_ERR)
181 	    || solo_dev->i2c_id < 0) {
182 		solo_i2c_stop(solo_dev);
183 		return -ENXIO;
184 	}
185 
186 	switch (solo_dev->i2c_state) {
187 	case IIC_STATE_START:
188 		if (solo_dev->i2c_msg->flags & I2C_M_RD) {
189 			solo_dev->i2c_state = IIC_STATE_READ;
190 			ret = solo_i2c_handle_read(solo_dev);
191 			break;
192 		}
193 
194 		solo_dev->i2c_state = IIC_STATE_WRITE;
195 	case IIC_STATE_WRITE:
196 		ret = solo_i2c_handle_write(solo_dev);
197 		break;
198 
199 	case IIC_STATE_READ:
200 		solo_dev->i2c_msg->buf[solo_dev->i2c_msg_ptr] =
201 			solo_reg_read(solo_dev, SOLO_IIC_RXD);
202 		solo_dev->i2c_msg_ptr++;
203 
204 		ret = solo_i2c_handle_read(solo_dev);
205 		break;
206 
207 	default:
208 		solo_i2c_stop(solo_dev);
209 	}
210 
211 	return ret;
212 }
213 
214 static int solo_i2c_master_xfer(struct i2c_adapter *adap,
215 				struct i2c_msg msgs[], int num)
216 {
217 	struct solo_dev *solo_dev = adap->algo_data;
218 	unsigned long timeout;
219 	int ret;
220 	int i;
221 	DEFINE_WAIT(wait);
222 
223 	for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
224 		if (&solo_dev->i2c_adap[i] == adap)
225 			break;
226 	}
227 
228 	if (i == SOLO_I2C_ADAPTERS)
229 		return num; /* XXX Right return value for failure? */
230 
231 	mutex_lock(&solo_dev->i2c_mutex);
232 	solo_dev->i2c_id = i;
233 	solo_dev->i2c_msg = msgs;
234 	solo_dev->i2c_msg_num = num;
235 	solo_dev->i2c_msg_ptr = 0;
236 
237 	solo_reg_write(solo_dev, SOLO_IIC_CTRL, 0);
238 	solo_irq_on(solo_dev, SOLO_IRQ_IIC);
239 	solo_i2c_start(solo_dev);
240 
241 	timeout = HZ / 2;
242 
243 	for (;;) {
244 		prepare_to_wait(&solo_dev->i2c_wait, &wait,
245 				TASK_INTERRUPTIBLE);
246 
247 		if (solo_dev->i2c_state == IIC_STATE_STOP)
248 			break;
249 
250 		timeout = schedule_timeout(timeout);
251 		if (!timeout)
252 			break;
253 
254 		if (signal_pending(current))
255 			break;
256 	}
257 
258 	finish_wait(&solo_dev->i2c_wait, &wait);
259 	ret = num - solo_dev->i2c_msg_num;
260 	solo_dev->i2c_state = IIC_STATE_IDLE;
261 	solo_dev->i2c_id = -1;
262 
263 	mutex_unlock(&solo_dev->i2c_mutex);
264 
265 	return ret;
266 }
267 
268 static u32 solo_i2c_functionality(struct i2c_adapter *adap)
269 {
270 	return I2C_FUNC_I2C;
271 }
272 
273 static const struct i2c_algorithm solo_i2c_algo = {
274 	.master_xfer	= solo_i2c_master_xfer,
275 	.functionality	= solo_i2c_functionality,
276 };
277 
278 int solo_i2c_init(struct solo_dev *solo_dev)
279 {
280 	int i;
281 	int ret;
282 
283 	solo_reg_write(solo_dev, SOLO_IIC_CFG,
284 		       SOLO_IIC_PRESCALE(8) | SOLO_IIC_ENABLE);
285 
286 	solo_dev->i2c_id = -1;
287 	solo_dev->i2c_state = IIC_STATE_IDLE;
288 	init_waitqueue_head(&solo_dev->i2c_wait);
289 	mutex_init(&solo_dev->i2c_mutex);
290 
291 	for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
292 		struct i2c_adapter *adap = &solo_dev->i2c_adap[i];
293 
294 		snprintf(adap->name, I2C_NAME_SIZE, "%s I2C %d",
295 			 SOLO6X10_NAME, i);
296 		adap->algo = &solo_i2c_algo;
297 		adap->algo_data = solo_dev;
298 		adap->retries = 1;
299 		adap->dev.parent = &solo_dev->pdev->dev;
300 
301 		ret = i2c_add_adapter(adap);
302 		if (ret) {
303 			adap->algo_data = NULL;
304 			break;
305 		}
306 	}
307 
308 	if (ret) {
309 		for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
310 			if (!solo_dev->i2c_adap[i].algo_data)
311 				break;
312 			i2c_del_adapter(&solo_dev->i2c_adap[i]);
313 			solo_dev->i2c_adap[i].algo_data = NULL;
314 		}
315 		return ret;
316 	}
317 
318 	return 0;
319 }
320 
321 void solo_i2c_exit(struct solo_dev *solo_dev)
322 {
323 	int i;
324 
325 	for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
326 		if (!solo_dev->i2c_adap[i].algo_data)
327 			continue;
328 		i2c_del_adapter(&solo_dev->i2c_adap[i]);
329 		solo_dev->i2c_adap[i].algo_data = NULL;
330 	}
331 }
332