1 /*
2  * Coral-P(A)/Lime I2C adapter driver
3  *
4  * (C) 2011 DENX Software Engineering, Anatolij Gustschin <agust@denx.de>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  *
10  */
11 
12 #include <linux/fb.h>
13 #include <linux/i2c.h>
14 #include <linux/io.h>
15 #include <linux/delay.h>
16 #include <linux/export.h>
17 
18 #include "mb862xxfb.h"
19 #include "mb862xx_reg.h"
20 
21 static int mb862xx_i2c_wait_event(struct i2c_adapter *adap)
22 {
23 	struct mb862xxfb_par *par = adap->algo_data;
24 	u32 reg;
25 
26 	do {
27 		udelay(10);
28 		reg = inreg(i2c, GC_I2C_BCR);
29 		if (reg & (I2C_INT | I2C_BER))
30 			break;
31 	} while (1);
32 
33 	return (reg & I2C_BER) ? 0 : 1;
34 }
35 
36 static int mb862xx_i2c_do_address(struct i2c_adapter *adap, int addr)
37 {
38 	struct mb862xxfb_par *par = adap->algo_data;
39 
40 	outreg(i2c, GC_I2C_DAR, addr);
41 	outreg(i2c, GC_I2C_CCR, I2C_CLOCK_AND_ENABLE);
42 	outreg(i2c, GC_I2C_BCR, par->i2c_rs ? I2C_REPEATED_START : I2C_START);
43 	if (!mb862xx_i2c_wait_event(adap))
44 		return -EIO;
45 	par->i2c_rs = !(inreg(i2c, GC_I2C_BSR) & I2C_LRB);
46 	return par->i2c_rs;
47 }
48 
49 static int mb862xx_i2c_write_byte(struct i2c_adapter *adap, u8 byte)
50 {
51 	struct mb862xxfb_par *par = adap->algo_data;
52 
53 	outreg(i2c, GC_I2C_DAR, byte);
54 	outreg(i2c, GC_I2C_BCR, I2C_START);
55 	if (!mb862xx_i2c_wait_event(adap))
56 		return -EIO;
57 	return !(inreg(i2c, GC_I2C_BSR) & I2C_LRB);
58 }
59 
60 static int mb862xx_i2c_read_byte(struct i2c_adapter *adap, u8 *byte, int last)
61 {
62 	struct mb862xxfb_par *par = adap->algo_data;
63 
64 	outreg(i2c, GC_I2C_BCR, I2C_START | (last ? 0 : I2C_ACK));
65 	if (!mb862xx_i2c_wait_event(adap))
66 		return 0;
67 	*byte = inreg(i2c, GC_I2C_DAR);
68 	return 1;
69 }
70 
71 static void mb862xx_i2c_stop(struct i2c_adapter *adap)
72 {
73 	struct mb862xxfb_par *par = adap->algo_data;
74 
75 	outreg(i2c, GC_I2C_BCR, I2C_STOP);
76 	outreg(i2c, GC_I2C_CCR, I2C_DISABLE);
77 	par->i2c_rs = 0;
78 }
79 
80 static int mb862xx_i2c_read(struct i2c_adapter *adap, struct i2c_msg *m)
81 {
82 	int i, ret = 0;
83 	int last = m->len - 1;
84 
85 	for (i = 0; i < m->len; i++) {
86 		if (!mb862xx_i2c_read_byte(adap, &m->buf[i], i == last)) {
87 			ret = -EIO;
88 			break;
89 		}
90 	}
91 	return ret;
92 }
93 
94 static int mb862xx_i2c_write(struct i2c_adapter *adap, struct i2c_msg *m)
95 {
96 	int i, ret = 0;
97 
98 	for (i = 0; i < m->len; i++) {
99 		if (!mb862xx_i2c_write_byte(adap, m->buf[i])) {
100 			ret = -EIO;
101 			break;
102 		}
103 	}
104 	return ret;
105 }
106 
107 static int mb862xx_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
108 			int num)
109 {
110 	struct mb862xxfb_par *par = adap->algo_data;
111 	struct i2c_msg *m;
112 	int addr;
113 	int i = 0, err = 0;
114 
115 	dev_dbg(par->dev, "%s: %d msgs\n", __func__, num);
116 
117 	for (i = 0; i < num; i++) {
118 		m = &msgs[i];
119 		if (!m->len) {
120 			dev_dbg(par->dev, "%s: null msgs\n", __func__);
121 			continue;
122 		}
123 		addr = m->addr;
124 		if (m->flags & I2C_M_RD)
125 			addr |= 1;
126 
127 		err = mb862xx_i2c_do_address(adap, addr);
128 		if (err < 0)
129 			break;
130 		if (m->flags & I2C_M_RD)
131 			err = mb862xx_i2c_read(adap, m);
132 		else
133 			err = mb862xx_i2c_write(adap, m);
134 	}
135 
136 	if (i)
137 		mb862xx_i2c_stop(adap);
138 
139 	return (err < 0) ? err : i;
140 }
141 
142 static u32 mb862xx_func(struct i2c_adapter *adap)
143 {
144 	return I2C_FUNC_SMBUS_BYTE_DATA;
145 }
146 
147 static const struct i2c_algorithm mb862xx_algo = {
148 	.master_xfer	= mb862xx_xfer,
149 	.functionality	= mb862xx_func,
150 };
151 
152 static struct i2c_adapter mb862xx_i2c_adapter = {
153 	.name		= "MB862xx I2C adapter",
154 	.algo		= &mb862xx_algo,
155 	.owner		= THIS_MODULE,
156 };
157 
158 int mb862xx_i2c_init(struct mb862xxfb_par *par)
159 {
160 	int ret;
161 
162 	mb862xx_i2c_adapter.algo_data = par;
163 	par->adap = &mb862xx_i2c_adapter;
164 
165 	ret = i2c_add_adapter(par->adap);
166 	if (ret < 0) {
167 		dev_err(par->dev, "failed to add %s\n",
168 			mb862xx_i2c_adapter.name);
169 	}
170 	return ret;
171 }
172 
173 void mb862xx_i2c_exit(struct mb862xxfb_par *par)
174 {
175 	if (par->adap) {
176 		i2c_del_adapter(par->adap);
177 		par->adap = NULL;
178 	}
179 }
180