1/*
2 * Copyright (C) 2010 Bluecherry, LLC www.bluecherrydvr.com
3 * Copyright (C) 2010 Ben Collins <bcollins@bluecherry.net>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
18 */
19
20/* XXX: The SOLO6x10 i2c does not have separate interrupts for each i2c
21 * channel. The bus can only handle one i2c event at a time. The below handles
22 * this all wrong. We should be using the status registers to see if the bus
23 * is in use, and have a global lock to check the status register. Also,
24 * the bulk of the work should be handled out-of-interrupt. The ugly loops
25 * that occur during interrupt scare me. The ISR should merely signal
26 * thread context, ACK the interrupt, and move on. -- BenC */
27
28#include <linux/kernel.h>
29#include "solo6x10.h"
30
31u8 solo_i2c_readbyte(struct solo_dev *solo_dev, int id, u8 addr, u8 off)
32{
33	struct i2c_msg msgs[2];
34	u8 data;
35
36	msgs[0].flags = 0;
37	msgs[0].addr = addr;
38	msgs[0].len = 1;
39	msgs[0].buf = &off;
40
41	msgs[1].flags = I2C_M_RD;
42	msgs[1].addr = addr;
43	msgs[1].len = 1;
44	msgs[1].buf = &data;
45
46	i2c_transfer(&solo_dev->i2c_adap[id], msgs, 2);
47
48	return data;
49}
50
51void solo_i2c_writebyte(struct solo_dev *solo_dev, int id, u8 addr,
52			u8 off, u8 data)
53{
54	struct i2c_msg msgs;
55	u8 buf[2];
56
57	buf[0] = off;
58	buf[1] = data;
59	msgs.flags = 0;
60	msgs.addr = addr;
61	msgs.len = 2;
62	msgs.buf = buf;
63
64	i2c_transfer(&solo_dev->i2c_adap[id], &msgs, 1);
65}
66
67static void solo_i2c_flush(struct solo_dev *solo_dev, int wr)
68{
69	u32 ctrl;
70
71	ctrl = SOLO_IIC_CH_SET(solo_dev->i2c_id);
72
73	if (solo_dev->i2c_state == IIC_STATE_START)
74		ctrl |= SOLO_IIC_START;
75
76	if (wr) {
77		ctrl |= SOLO_IIC_WRITE;
78	} else {
79		ctrl |= SOLO_IIC_READ;
80		if (!(solo_dev->i2c_msg->flags & I2C_M_NO_RD_ACK))
81			ctrl |= SOLO_IIC_ACK_EN;
82	}
83
84	if (solo_dev->i2c_msg_ptr == solo_dev->i2c_msg->len)
85		ctrl |= SOLO_IIC_STOP;
86
87	solo_reg_write(solo_dev, SOLO_IIC_CTRL, ctrl);
88}
89
90static void solo_i2c_start(struct solo_dev *solo_dev)
91{
92	u32 addr = solo_dev->i2c_msg->addr << 1;
93
94	if (solo_dev->i2c_msg->flags & I2C_M_RD)
95		addr |= 1;
96
97	solo_dev->i2c_state = IIC_STATE_START;
98	solo_reg_write(solo_dev, SOLO_IIC_TXD, addr);
99	solo_i2c_flush(solo_dev, 1);
100}
101
102static void solo_i2c_stop(struct solo_dev *solo_dev)
103{
104	solo_irq_off(solo_dev, SOLO_IRQ_IIC);
105	solo_reg_write(solo_dev, SOLO_IIC_CTRL, 0);
106	solo_dev->i2c_state = IIC_STATE_STOP;
107	wake_up(&solo_dev->i2c_wait);
108}
109
110static int solo_i2c_handle_read(struct solo_dev *solo_dev)
111{
112prepare_read:
113	if (solo_dev->i2c_msg_ptr != solo_dev->i2c_msg->len) {
114		solo_i2c_flush(solo_dev, 0);
115		return 0;
116	}
117
118	solo_dev->i2c_msg_ptr = 0;
119	solo_dev->i2c_msg++;
120	solo_dev->i2c_msg_num--;
121
122	if (solo_dev->i2c_msg_num == 0) {
123		solo_i2c_stop(solo_dev);
124		return 0;
125	}
126
127	if (!(solo_dev->i2c_msg->flags & I2C_M_NOSTART)) {
128		solo_i2c_start(solo_dev);
129	} else {
130		if (solo_dev->i2c_msg->flags & I2C_M_RD)
131			goto prepare_read;
132		else
133			solo_i2c_stop(solo_dev);
134	}
135
136	return 0;
137}
138
139static int solo_i2c_handle_write(struct solo_dev *solo_dev)
140{
141retry_write:
142	if (solo_dev->i2c_msg_ptr != solo_dev->i2c_msg->len) {
143		solo_reg_write(solo_dev, SOLO_IIC_TXD,
144			       solo_dev->i2c_msg->buf[solo_dev->i2c_msg_ptr]);
145		solo_dev->i2c_msg_ptr++;
146		solo_i2c_flush(solo_dev, 1);
147		return 0;
148	}
149
150	solo_dev->i2c_msg_ptr = 0;
151	solo_dev->i2c_msg++;
152	solo_dev->i2c_msg_num--;
153
154	if (solo_dev->i2c_msg_num == 0) {
155		solo_i2c_stop(solo_dev);
156		return 0;
157	}
158
159	if (!(solo_dev->i2c_msg->flags & I2C_M_NOSTART)) {
160		solo_i2c_start(solo_dev);
161	} else {
162		if (solo_dev->i2c_msg->flags & I2C_M_RD)
163			solo_i2c_stop(solo_dev);
164		else
165			goto retry_write;
166	}
167
168	return 0;
169}
170
171int solo_i2c_isr(struct solo_dev *solo_dev)
172{
173	u32 status = solo_reg_read(solo_dev, SOLO_IIC_CTRL);
174	int ret = -EINVAL;
175
176	solo_reg_write(solo_dev, SOLO_IRQ_STAT, SOLO_IRQ_IIC);
177
178	if (status & (SOLO_IIC_STATE_TRNS & SOLO_IIC_STATE_SIG_ERR) ||
179	    solo_dev->i2c_id < 0) {
180		solo_i2c_stop(solo_dev);
181		return -ENXIO;
182	}
183
184	switch (solo_dev->i2c_state) {
185	case IIC_STATE_START:
186		if (solo_dev->i2c_msg->flags & I2C_M_RD) {
187			solo_dev->i2c_state = IIC_STATE_READ;
188			ret = solo_i2c_handle_read(solo_dev);
189			break;
190		}
191
192		solo_dev->i2c_state = IIC_STATE_WRITE;
193	case IIC_STATE_WRITE:
194		ret = solo_i2c_handle_write(solo_dev);
195		break;
196
197	case IIC_STATE_READ:
198		solo_dev->i2c_msg->buf[solo_dev->i2c_msg_ptr] =
199			solo_reg_read(solo_dev, SOLO_IIC_RXD);
200		solo_dev->i2c_msg_ptr++;
201
202		ret = solo_i2c_handle_read(solo_dev);
203		break;
204
205	default:
206		solo_i2c_stop(solo_dev);
207	}
208
209	return ret;
210}
211
212static int solo_i2c_master_xfer(struct i2c_adapter *adap,
213				struct i2c_msg msgs[], int num)
214{
215	struct solo_dev *solo_dev = adap->algo_data;
216	unsigned long timeout;
217	int ret;
218	int i;
219	DEFINE_WAIT(wait);
220
221	for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
222		if (&solo_dev->i2c_adap[i] == adap)
223			break;
224	}
225
226	if (i == SOLO_I2C_ADAPTERS)
227		return num; /* XXX Right return value for failure? */
228
229	mutex_lock(&solo_dev->i2c_mutex);
230	solo_dev->i2c_id = i;
231	solo_dev->i2c_msg = msgs;
232	solo_dev->i2c_msg_num = num;
233	solo_dev->i2c_msg_ptr = 0;
234
235	solo_reg_write(solo_dev, SOLO_IIC_CTRL, 0);
236	solo_irq_on(solo_dev, SOLO_IRQ_IIC);
237	solo_i2c_start(solo_dev);
238
239	timeout = HZ / 2;
240
241	for (;;) {
242		prepare_to_wait(&solo_dev->i2c_wait, &wait, TASK_INTERRUPTIBLE);
243
244		if (solo_dev->i2c_state == IIC_STATE_STOP)
245			break;
246
247		timeout = schedule_timeout(timeout);
248		if (!timeout)
249			break;
250
251		if (signal_pending(current))
252			break;
253	}
254
255	finish_wait(&solo_dev->i2c_wait, &wait);
256	ret = num - solo_dev->i2c_msg_num;
257	solo_dev->i2c_state = IIC_STATE_IDLE;
258	solo_dev->i2c_id = -1;
259
260	mutex_unlock(&solo_dev->i2c_mutex);
261
262	return ret;
263}
264
265static u32 solo_i2c_functionality(struct i2c_adapter *adap)
266{
267	return I2C_FUNC_I2C;
268}
269
270static struct i2c_algorithm solo_i2c_algo = {
271	.master_xfer	= solo_i2c_master_xfer,
272	.functionality	= solo_i2c_functionality,
273};
274
275int solo_i2c_init(struct solo_dev *solo_dev)
276{
277	int i;
278	int ret;
279
280	solo_reg_write(solo_dev, SOLO_IIC_CFG,
281		       SOLO_IIC_PRESCALE(8) | SOLO_IIC_ENABLE);
282
283	solo_dev->i2c_id = -1;
284	solo_dev->i2c_state = IIC_STATE_IDLE;
285	init_waitqueue_head(&solo_dev->i2c_wait);
286	mutex_init(&solo_dev->i2c_mutex);
287
288	for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
289		struct i2c_adapter *adap = &solo_dev->i2c_adap[i];
290
291		snprintf(adap->name, I2C_NAME_SIZE, "%s I2C %d", SOLO6X10_NAME, i);
292		adap->algo = &solo_i2c_algo;
293		adap->algo_data = solo_dev;
294		adap->retries = 1;
295		adap->dev.parent = &solo_dev->pdev->dev;
296
297		ret = i2c_add_adapter(adap);
298		if (ret) {
299			adap->algo_data = NULL;
300			break;
301		}
302	}
303
304	if (ret) {
305		for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
306			if (!solo_dev->i2c_adap[i].algo_data)
307				break;
308			i2c_del_adapter(&solo_dev->i2c_adap[i]);
309			solo_dev->i2c_adap[i].algo_data = NULL;
310		}
311		return ret;
312	}
313
314	dev_info(&solo_dev->pdev->dev, "Enabled %d i2c adapters\n",
315		 SOLO_I2C_ADAPTERS);
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