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
17static 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
32static 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
45static 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
56static 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
67static 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
76static 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
90static 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
103static 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
138static u32 mb862xx_func(struct i2c_adapter *adap)
139{
140	return I2C_FUNC_SMBUS_BYTE_DATA;
141}
142
143static const struct i2c_algorithm mb862xx_algo = {
144	.master_xfer	= mb862xx_xfer,
145	.functionality	= mb862xx_func,
146};
147
148static struct i2c_adapter mb862xx_i2c_adapter = {
149	.name		= "MB862xx I2C adapter",
150	.algo		= &mb862xx_algo,
151	.owner		= THIS_MODULE,
152};
153
154int 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
162void 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