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
25u8 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
45void 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
61static 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
84static 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
96static 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
104static int solo_i2c_handle_read(struct solo_dev *solo_dev)
105{
106prepare_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
133static int solo_i2c_handle_write(struct solo_dev *solo_dev)
134{
135retry_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
165int 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
206static 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
260static u32 solo_i2c_functionality(struct i2c_adapter *adap)
261{
262	return I2C_FUNC_I2C;
263}
264
265static const struct i2c_algorithm solo_i2c_algo = {
266	.master_xfer	= solo_i2c_master_xfer,
267	.functionality	= solo_i2c_functionality,
268};
269
270int 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
313void 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