1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Coral-P(A)/Lime I2C adapter driver
4  *
5  * (C) 2011 DENX Software Engineering, Anatolij Gustschin <agust@denx.de>
6  */
7 
8 #include <linux/fb.h>
9 #include <linux/i2c.h>
10 #include <linux/io.h>
11 #include <linux/delay.h>
12 #include <linux/export.h>
13 
14 #include "mb862xxfb.h"
15 #include "mb862xx_reg.h"
16 
mb862xx_i2c_wait_event(struct i2c_adapter * adap)17 static int mb862xx_i2c_wait_event(struct i2c_adapter *adap)
18 {
19 	struct mb862xxfb_par *par = adap->algo_data;
20 	u32 reg;
21 
22 	do {
23 		udelay(10);
24 		reg = inreg(i2c, GC_I2C_BCR);
25 		if (reg & (I2C_INT | I2C_BER))
26 			break;
27 	} while (1);
28 
29 	return (reg & I2C_BER) ? 0 : 1;
30 }
31 
mb862xx_i2c_do_address(struct i2c_adapter * adap,int addr)32 static int mb862xx_i2c_do_address(struct i2c_adapter *adap, int addr)
33 {
34 	struct mb862xxfb_par *par = adap->algo_data;
35 
36 	outreg(i2c, GC_I2C_DAR, addr);
37 	outreg(i2c, GC_I2C_CCR, I2C_CLOCK_AND_ENABLE);
38 	outreg(i2c, GC_I2C_BCR, par->i2c_rs ? I2C_REPEATED_START : I2C_START);
39 	if (!mb862xx_i2c_wait_event(adap))
40 		return -EIO;
41 	par->i2c_rs = !(inreg(i2c, GC_I2C_BSR) & I2C_LRB);
42 	return par->i2c_rs;
43 }
44 
mb862xx_i2c_write_byte(struct i2c_adapter * adap,u8 byte)45 static int mb862xx_i2c_write_byte(struct i2c_adapter *adap, u8 byte)
46 {
47 	struct mb862xxfb_par *par = adap->algo_data;
48 
49 	outreg(i2c, GC_I2C_DAR, byte);
50 	outreg(i2c, GC_I2C_BCR, I2C_START);
51 	if (!mb862xx_i2c_wait_event(adap))
52 		return -EIO;
53 	return !(inreg(i2c, GC_I2C_BSR) & I2C_LRB);
54 }
55 
mb862xx_i2c_read_byte(struct i2c_adapter * adap,u8 * byte,int last)56 static int mb862xx_i2c_read_byte(struct i2c_adapter *adap, u8 *byte, int last)
57 {
58 	struct mb862xxfb_par *par = adap->algo_data;
59 
60 	outreg(i2c, GC_I2C_BCR, I2C_START | (last ? 0 : I2C_ACK));
61 	if (!mb862xx_i2c_wait_event(adap))
62 		return 0;
63 	*byte = inreg(i2c, GC_I2C_DAR);
64 	return 1;
65 }
66 
mb862xx_i2c_stop(struct i2c_adapter * adap)67 static void mb862xx_i2c_stop(struct i2c_adapter *adap)
68 {
69 	struct mb862xxfb_par *par = adap->algo_data;
70 
71 	outreg(i2c, GC_I2C_BCR, I2C_STOP);
72 	outreg(i2c, GC_I2C_CCR, I2C_DISABLE);
73 	par->i2c_rs = 0;
74 }
75 
mb862xx_i2c_read(struct i2c_adapter * adap,struct i2c_msg * m)76 static int mb862xx_i2c_read(struct i2c_adapter *adap, struct i2c_msg *m)
77 {
78 	int i, ret = 0;
79 	int last = m->len - 1;
80 
81 	for (i = 0; i < m->len; i++) {
82 		if (!mb862xx_i2c_read_byte(adap, &m->buf[i], i == last)) {
83 			ret = -EIO;
84 			break;
85 		}
86 	}
87 	return ret;
88 }
89 
mb862xx_i2c_write(struct i2c_adapter * adap,struct i2c_msg * m)90 static int mb862xx_i2c_write(struct i2c_adapter *adap, struct i2c_msg *m)
91 {
92 	int i, ret = 0;
93 
94 	for (i = 0; i < m->len; i++) {
95 		if (!mb862xx_i2c_write_byte(adap, m->buf[i])) {
96 			ret = -EIO;
97 			break;
98 		}
99 	}
100 	return ret;
101 }
102 
mb862xx_xfer(struct i2c_adapter * adap,struct i2c_msg * msgs,int num)103 static int mb862xx_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
104 			int num)
105 {
106 	struct mb862xxfb_par *par = adap->algo_data;
107 	struct i2c_msg *m;
108 	int addr;
109 	int i = 0, err = 0;
110 
111 	dev_dbg(par->dev, "%s: %d msgs\n", __func__, num);
112 
113 	for (i = 0; i < num; i++) {
114 		m = &msgs[i];
115 		if (!m->len) {
116 			dev_dbg(par->dev, "%s: null msgs\n", __func__);
117 			continue;
118 		}
119 		addr = m->addr;
120 		if (m->flags & I2C_M_RD)
121 			addr |= 1;
122 
123 		err = mb862xx_i2c_do_address(adap, addr);
124 		if (err < 0)
125 			break;
126 		if (m->flags & I2C_M_RD)
127 			err = mb862xx_i2c_read(adap, m);
128 		else
129 			err = mb862xx_i2c_write(adap, m);
130 	}
131 
132 	if (i)
133 		mb862xx_i2c_stop(adap);
134 
135 	return (err < 0) ? err : i;
136 }
137 
mb862xx_func(struct i2c_adapter * adap)138 static u32 mb862xx_func(struct i2c_adapter *adap)
139 {
140 	return I2C_FUNC_SMBUS_BYTE_DATA;
141 }
142 
143 static const struct i2c_algorithm mb862xx_algo = {
144 	.master_xfer	= mb862xx_xfer,
145 	.functionality	= mb862xx_func,
146 };
147 
148 static struct i2c_adapter mb862xx_i2c_adapter = {
149 	.name		= "MB862xx I2C adapter",
150 	.algo		= &mb862xx_algo,
151 	.owner		= THIS_MODULE,
152 };
153 
mb862xx_i2c_init(struct mb862xxfb_par * par)154 int mb862xx_i2c_init(struct mb862xxfb_par *par)
155 {
156 	mb862xx_i2c_adapter.algo_data = par;
157 	par->adap = &mb862xx_i2c_adapter;
158 
159 	return i2c_add_adapter(par->adap);
160 }
161 
mb862xx_i2c_exit(struct mb862xxfb_par * par)162 void mb862xx_i2c_exit(struct mb862xxfb_par *par)
163 {
164 	if (par->adap) {
165 		i2c_del_adapter(par->adap);
166 		par->adap = NULL;
167 	}
168 }
169