1/*
2 * Copyright 2012 Red Hat Inc.
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice shall be included in
12 * all copies or substantial portions of the Software.
13 *
14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
17 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
18 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
19 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
20 * OTHER DEALINGS IN THE SOFTWARE.
21 *
22 * Authors: Ben Skeggs
23 */
24
25#include "priv.h"
26
27#ifdef CONFIG_NOUVEAU_I2C_INTERNAL
28#define T_TIMEOUT  2200000
29#define T_RISEFALL 1000
30#define T_HOLD     5000
31
32static inline void
33i2c_drive_scl(struct nouveau_i2c_port *port, int state)
34{
35	port->func->drive_scl(port, state);
36}
37
38static inline void
39i2c_drive_sda(struct nouveau_i2c_port *port, int state)
40{
41	port->func->drive_sda(port, state);
42}
43
44static inline int
45i2c_sense_scl(struct nouveau_i2c_port *port)
46{
47	return port->func->sense_scl(port);
48}
49
50static inline int
51i2c_sense_sda(struct nouveau_i2c_port *port)
52{
53	return port->func->sense_sda(port);
54}
55
56static void
57i2c_delay(struct nouveau_i2c_port *port, u32 nsec)
58{
59	udelay((nsec + 500) / 1000);
60}
61
62static bool
63i2c_raise_scl(struct nouveau_i2c_port *port)
64{
65	u32 timeout = T_TIMEOUT / T_RISEFALL;
66
67	i2c_drive_scl(port, 1);
68	do {
69		i2c_delay(port, T_RISEFALL);
70	} while (!i2c_sense_scl(port) && --timeout);
71
72	return timeout != 0;
73}
74
75static int
76i2c_start(struct nouveau_i2c_port *port)
77{
78	int ret = 0;
79
80	if (!i2c_sense_scl(port) ||
81	    !i2c_sense_sda(port)) {
82		i2c_drive_scl(port, 0);
83		i2c_drive_sda(port, 1);
84		if (!i2c_raise_scl(port))
85			ret = -EBUSY;
86	}
87
88	i2c_drive_sda(port, 0);
89	i2c_delay(port, T_HOLD);
90	i2c_drive_scl(port, 0);
91	i2c_delay(port, T_HOLD);
92	return ret;
93}
94
95static void
96i2c_stop(struct nouveau_i2c_port *port)
97{
98	i2c_drive_scl(port, 0);
99	i2c_drive_sda(port, 0);
100	i2c_delay(port, T_RISEFALL);
101
102	i2c_drive_scl(port, 1);
103	i2c_delay(port, T_HOLD);
104	i2c_drive_sda(port, 1);
105	i2c_delay(port, T_HOLD);
106}
107
108static int
109i2c_bitw(struct nouveau_i2c_port *port, int sda)
110{
111	i2c_drive_sda(port, sda);
112	i2c_delay(port, T_RISEFALL);
113
114	if (!i2c_raise_scl(port))
115		return -ETIMEDOUT;
116	i2c_delay(port, T_HOLD);
117
118	i2c_drive_scl(port, 0);
119	i2c_delay(port, T_HOLD);
120	return 0;
121}
122
123static int
124i2c_bitr(struct nouveau_i2c_port *port)
125{
126	int sda;
127
128	i2c_drive_sda(port, 1);
129	i2c_delay(port, T_RISEFALL);
130
131	if (!i2c_raise_scl(port))
132		return -ETIMEDOUT;
133	i2c_delay(port, T_HOLD);
134
135	sda = i2c_sense_sda(port);
136
137	i2c_drive_scl(port, 0);
138	i2c_delay(port, T_HOLD);
139	return sda;
140}
141
142static int
143i2c_get_byte(struct nouveau_i2c_port *port, u8 *byte, bool last)
144{
145	int i, bit;
146
147	*byte = 0;
148	for (i = 7; i >= 0; i--) {
149		bit = i2c_bitr(port);
150		if (bit < 0)
151			return bit;
152		*byte |= bit << i;
153	}
154
155	return i2c_bitw(port, last ? 1 : 0);
156}
157
158static int
159i2c_put_byte(struct nouveau_i2c_port *port, u8 byte)
160{
161	int i, ret;
162	for (i = 7; i >= 0; i--) {
163		ret = i2c_bitw(port, !!(byte & (1 << i)));
164		if (ret < 0)
165			return ret;
166	}
167
168	ret = i2c_bitr(port);
169	if (ret == 1) /* nack */
170		ret = -EIO;
171	return ret;
172}
173
174static int
175i2c_addr(struct nouveau_i2c_port *port, struct i2c_msg *msg)
176{
177	u32 addr = msg->addr << 1;
178	if (msg->flags & I2C_M_RD)
179		addr |= 1;
180	return i2c_put_byte(port, addr);
181}
182
183static int
184i2c_bit_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
185{
186	struct nouveau_i2c_port *port = adap->algo_data;
187	struct i2c_msg *msg = msgs;
188	int ret = 0, mcnt = num;
189
190	ret = nouveau_i2c(port)->acquire(port, nsecs_to_jiffies(T_TIMEOUT));
191	if (ret)
192		return ret;
193
194	while (!ret && mcnt--) {
195		u8 remaining = msg->len;
196		u8 *ptr = msg->buf;
197
198		ret = i2c_start(port);
199		if (ret == 0)
200			ret = i2c_addr(port, msg);
201
202		if (msg->flags & I2C_M_RD) {
203			while (!ret && remaining--)
204				ret = i2c_get_byte(port, ptr++, !remaining);
205		} else {
206			while (!ret && remaining--)
207				ret = i2c_put_byte(port, *ptr++);
208		}
209
210		msg++;
211	}
212
213	i2c_stop(port);
214	nouveau_i2c(port)->release(port);
215	return (ret < 0) ? ret : num;
216}
217#else
218static int
219i2c_bit_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
220{
221	return -ENODEV;
222}
223#endif
224
225static u32
226i2c_bit_func(struct i2c_adapter *adap)
227{
228	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
229}
230
231const struct i2c_algorithm nouveau_i2c_bit_algo = {
232	.master_xfer = i2c_bit_xfer,
233	.functionality = i2c_bit_func
234};
235