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
33u8 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
53void 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
69static 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
92static 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
104static 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
112static int solo_i2c_handle_read(struct solo_dev *solo_dev)
113{
114prepare_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
141static int solo_i2c_handle_write(struct solo_dev *solo_dev)
142{
143retry_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
173int 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
213static 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
267static u32 solo_i2c_functionality(struct i2c_adapter *adap)
268{
269	return I2C_FUNC_I2C;
270}
271
272static const struct i2c_algorithm solo_i2c_algo = {
273	.master_xfer	= solo_i2c_master_xfer,
274	.functionality	= solo_i2c_functionality,
275};
276
277int 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
320void 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