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 
31 #include "solo6x10.h"
32 
33 u8 solo_i2c_readbyte(struct solo_dev *solo_dev, int id, u8 addr, u8 off)
34 {
35 	struct i2c_msg msgs[2];
36 	u8 data;
37 
38 	msgs[0].flags = 0;
39 	msgs[0].addr = addr;
40 	msgs[0].len = 1;
41 	msgs[0].buf = &off;
42 
43 	msgs[1].flags = I2C_M_RD;
44 	msgs[1].addr = addr;
45 	msgs[1].len = 1;
46 	msgs[1].buf = &data;
47 
48 	i2c_transfer(&solo_dev->i2c_adap[id], msgs, 2);
49 
50 	return data;
51 }
52 
53 void solo_i2c_writebyte(struct solo_dev *solo_dev, int id, u8 addr,
54 			u8 off, u8 data)
55 {
56 	struct i2c_msg msgs;
57 	u8 buf[2];
58 
59 	buf[0] = off;
60 	buf[1] = data;
61 	msgs.flags = 0;
62 	msgs.addr = addr;
63 	msgs.len = 2;
64 	msgs.buf = buf;
65 
66 	i2c_transfer(&solo_dev->i2c_adap[id], &msgs, 1);
67 }
68 
69 static void solo_i2c_flush(struct solo_dev *solo_dev, int wr)
70 {
71 	u32 ctrl;
72 
73 	ctrl = SOLO_IIC_CH_SET(solo_dev->i2c_id);
74 
75 	if (solo_dev->i2c_state == IIC_STATE_START)
76 		ctrl |= SOLO_IIC_START;
77 
78 	if (wr) {
79 		ctrl |= SOLO_IIC_WRITE;
80 	} else {
81 		ctrl |= SOLO_IIC_READ;
82 		if (!(solo_dev->i2c_msg->flags & I2C_M_NO_RD_ACK))
83 			ctrl |= SOLO_IIC_ACK_EN;
84 	}
85 
86 	if (solo_dev->i2c_msg_ptr == solo_dev->i2c_msg->len)
87 		ctrl |= SOLO_IIC_STOP;
88 
89 	solo_reg_write(solo_dev, SOLO_IIC_CTRL, ctrl);
90 }
91 
92 static void solo_i2c_start(struct solo_dev *solo_dev)
93 {
94 	u32 addr = solo_dev->i2c_msg->addr << 1;
95 
96 	if (solo_dev->i2c_msg->flags & I2C_M_RD)
97 		addr |= 1;
98 
99 	solo_dev->i2c_state = IIC_STATE_START;
100 	solo_reg_write(solo_dev, SOLO_IIC_TXD, addr);
101 	solo_i2c_flush(solo_dev, 1);
102 }
103 
104 static void solo_i2c_stop(struct solo_dev *solo_dev)
105 {
106 	solo_irq_off(solo_dev, SOLO_IRQ_IIC);
107 	solo_reg_write(solo_dev, SOLO_IIC_CTRL, 0);
108 	solo_dev->i2c_state = IIC_STATE_STOP;
109 	wake_up(&solo_dev->i2c_wait);
110 }
111 
112 static int solo_i2c_handle_read(struct solo_dev *solo_dev)
113 {
114 prepare_read:
115 	if (solo_dev->i2c_msg_ptr != solo_dev->i2c_msg->len) {
116 		solo_i2c_flush(solo_dev, 0);
117 		return 0;
118 	}
119 
120 	solo_dev->i2c_msg_ptr = 0;
121 	solo_dev->i2c_msg++;
122 	solo_dev->i2c_msg_num--;
123 
124 	if (solo_dev->i2c_msg_num == 0) {
125 		solo_i2c_stop(solo_dev);
126 		return 0;
127 	}
128 
129 	if (!(solo_dev->i2c_msg->flags & I2C_M_NOSTART)) {
130 		solo_i2c_start(solo_dev);
131 	} else {
132 		if (solo_dev->i2c_msg->flags & I2C_M_RD)
133 			goto prepare_read;
134 		else
135 			solo_i2c_stop(solo_dev);
136 	}
137 
138 	return 0;
139 }
140 
141 static int solo_i2c_handle_write(struct solo_dev *solo_dev)
142 {
143 retry_write:
144 	if (solo_dev->i2c_msg_ptr != solo_dev->i2c_msg->len) {
145 		solo_reg_write(solo_dev, SOLO_IIC_TXD,
146 			       solo_dev->i2c_msg->buf[solo_dev->i2c_msg_ptr]);
147 		solo_dev->i2c_msg_ptr++;
148 		solo_i2c_flush(solo_dev, 1);
149 		return 0;
150 	}
151 
152 	solo_dev->i2c_msg_ptr = 0;
153 	solo_dev->i2c_msg++;
154 	solo_dev->i2c_msg_num--;
155 
156 	if (solo_dev->i2c_msg_num == 0) {
157 		solo_i2c_stop(solo_dev);
158 		return 0;
159 	}
160 
161 	if (!(solo_dev->i2c_msg->flags & I2C_M_NOSTART)) {
162 		solo_i2c_start(solo_dev);
163 	} else {
164 		if (solo_dev->i2c_msg->flags & I2C_M_RD)
165 			solo_i2c_stop(solo_dev);
166 		else
167 			goto retry_write;
168 	}
169 
170 	return 0;
171 }
172 
173 int solo_i2c_isr(struct solo_dev *solo_dev)
174 {
175 	u32 status = solo_reg_read(solo_dev, SOLO_IIC_CTRL);
176 	int ret = -EINVAL;
177 
178 
179 	if (CHK_FLAGS(status, SOLO_IIC_STATE_TRNS | SOLO_IIC_STATE_SIG_ERR)
180 	    || solo_dev->i2c_id < 0) {
181 		solo_i2c_stop(solo_dev);
182 		return -ENXIO;
183 	}
184 
185 	switch (solo_dev->i2c_state) {
186 	case IIC_STATE_START:
187 		if (solo_dev->i2c_msg->flags & I2C_M_RD) {
188 			solo_dev->i2c_state = IIC_STATE_READ;
189 			ret = solo_i2c_handle_read(solo_dev);
190 			break;
191 		}
192 
193 		solo_dev->i2c_state = IIC_STATE_WRITE;
194 	case IIC_STATE_WRITE:
195 		ret = solo_i2c_handle_write(solo_dev);
196 		break;
197 
198 	case IIC_STATE_READ:
199 		solo_dev->i2c_msg->buf[solo_dev->i2c_msg_ptr] =
200 			solo_reg_read(solo_dev, SOLO_IIC_RXD);
201 		solo_dev->i2c_msg_ptr++;
202 
203 		ret = solo_i2c_handle_read(solo_dev);
204 		break;
205 
206 	default:
207 		solo_i2c_stop(solo_dev);
208 	}
209 
210 	return ret;
211 }
212 
213 static int solo_i2c_master_xfer(struct i2c_adapter *adap,
214 				struct i2c_msg msgs[], int num)
215 {
216 	struct solo_dev *solo_dev = adap->algo_data;
217 	unsigned long timeout;
218 	int ret;
219 	int i;
220 	DEFINE_WAIT(wait);
221 
222 	for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
223 		if (&solo_dev->i2c_adap[i] == adap)
224 			break;
225 	}
226 
227 	if (i == SOLO_I2C_ADAPTERS)
228 		return num; /* XXX Right return value for failure? */
229 
230 	mutex_lock(&solo_dev->i2c_mutex);
231 	solo_dev->i2c_id = i;
232 	solo_dev->i2c_msg = msgs;
233 	solo_dev->i2c_msg_num = num;
234 	solo_dev->i2c_msg_ptr = 0;
235 
236 	solo_reg_write(solo_dev, SOLO_IIC_CTRL, 0);
237 	solo_irq_on(solo_dev, SOLO_IRQ_IIC);
238 	solo_i2c_start(solo_dev);
239 
240 	timeout = HZ / 2;
241 
242 	for (;;) {
243 		prepare_to_wait(&solo_dev->i2c_wait, &wait,
244 				TASK_INTERRUPTIBLE);
245 
246 		if (solo_dev->i2c_state == IIC_STATE_STOP)
247 			break;
248 
249 		timeout = schedule_timeout(timeout);
250 		if (!timeout)
251 			break;
252 
253 		if (signal_pending(current))
254 			break;
255 	}
256 
257 	finish_wait(&solo_dev->i2c_wait, &wait);
258 	ret = num - solo_dev->i2c_msg_num;
259 	solo_dev->i2c_state = IIC_STATE_IDLE;
260 	solo_dev->i2c_id = -1;
261 
262 	mutex_unlock(&solo_dev->i2c_mutex);
263 
264 	return ret;
265 }
266 
267 static u32 solo_i2c_functionality(struct i2c_adapter *adap)
268 {
269 	return I2C_FUNC_I2C;
270 }
271 
272 static const struct i2c_algorithm solo_i2c_algo = {
273 	.master_xfer	= solo_i2c_master_xfer,
274 	.functionality	= solo_i2c_functionality,
275 };
276 
277 int solo_i2c_init(struct solo_dev *solo_dev)
278 {
279 	int i;
280 	int ret;
281 
282 	solo_reg_write(solo_dev, SOLO_IIC_CFG,
283 		       SOLO_IIC_PRESCALE(8) | SOLO_IIC_ENABLE);
284 
285 	solo_dev->i2c_id = -1;
286 	solo_dev->i2c_state = IIC_STATE_IDLE;
287 	init_waitqueue_head(&solo_dev->i2c_wait);
288 	mutex_init(&solo_dev->i2c_mutex);
289 
290 	for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
291 		struct i2c_adapter *adap = &solo_dev->i2c_adap[i];
292 
293 		snprintf(adap->name, I2C_NAME_SIZE, "%s I2C %d",
294 			 SOLO6X10_NAME, i);
295 		adap->algo = &solo_i2c_algo;
296 		adap->algo_data = solo_dev;
297 		adap->retries = 1;
298 		adap->dev.parent = &solo_dev->pdev->dev;
299 
300 		ret = i2c_add_adapter(adap);
301 		if (ret) {
302 			adap->algo_data = NULL;
303 			break;
304 		}
305 	}
306 
307 	if (ret) {
308 		for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
309 			if (!solo_dev->i2c_adap[i].algo_data)
310 				break;
311 			i2c_del_adapter(&solo_dev->i2c_adap[i]);
312 			solo_dev->i2c_adap[i].algo_data = NULL;
313 		}
314 		return ret;
315 	}
316 
317 	return 0;
318 }
319 
320 void solo_i2c_exit(struct solo_dev *solo_dev)
321 {
322 	int i;
323 
324 	for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
325 		if (!solo_dev->i2c_adap[i].algo_data)
326 			continue;
327 		i2c_del_adapter(&solo_dev->i2c_adap[i]);
328 		solo_dev->i2c_adap[i].algo_data = NULL;
329 	}
330 }
331