mb862xx-i2c.c

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