1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
|
// SPDX-License-Identifier: GPL-2.0
/*
* i2c slave support for Atmel's AT91 Two-Wire Interface (TWI)
*
* Copyright (C) 2017 Juergen Fitschen <me@jue.yt>
*/
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/pm_runtime.h>
#include "i2c-at91.h"
static irqreturn_t atmel_twi_interrupt_slave(int irq, void *dev_id)
{
struct at91_twi_dev *dev = dev_id;
const unsigned status = at91_twi_read(dev, AT91_TWI_SR);
const unsigned irqstatus = status & at91_twi_read(dev, AT91_TWI_IMR);
u8 value;
if (!irqstatus)
return IRQ_NONE;
/* slave address has been detected on I2C bus */
if (irqstatus & AT91_TWI_SVACC) {
if (status & AT91_TWI_SVREAD) {
i2c_slave_event(dev->slave,
I2C_SLAVE_READ_REQUESTED, &value);
writeb_relaxed(value, dev->base + AT91_TWI_THR);
at91_twi_write(dev, AT91_TWI_IER,
AT91_TWI_TXRDY | AT91_TWI_EOSACC);
} else {
i2c_slave_event(dev->slave,
I2C_SLAVE_WRITE_REQUESTED, &value);
at91_twi_write(dev, AT91_TWI_IER,
AT91_TWI_RXRDY | AT91_TWI_EOSACC);
}
at91_twi_write(dev, AT91_TWI_IDR, AT91_TWI_SVACC);
}
/* byte transmitted to remote master */
if (irqstatus & AT91_TWI_TXRDY) {
i2c_slave_event(dev->slave, I2C_SLAVE_READ_PROCESSED, &value);
writeb_relaxed(value, dev->base + AT91_TWI_THR);
}
/* byte received from remote master */
if (irqstatus & AT91_TWI_RXRDY) {
value = readb_relaxed(dev->base + AT91_TWI_RHR);
i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_RECEIVED, &value);
}
/* master sent stop */
if (irqstatus & AT91_TWI_EOSACC) {
at91_twi_write(dev, AT91_TWI_IDR,
AT91_TWI_TXRDY | AT91_TWI_RXRDY | AT91_TWI_EOSACC);
at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_SVACC);
i2c_slave_event(dev->slave, I2C_SLAVE_STOP, &value);
}
return IRQ_HANDLED;
}
static int at91_reg_slave(struct i2c_client *slave)
{
struct at91_twi_dev *dev = i2c_get_adapdata(slave->adapter);
if (dev->slave)
return -EBUSY;
if (slave->flags & I2C_CLIENT_TEN)
return -EAFNOSUPPORT;
/* Make sure twi_clk doesn't get turned off! */
pm_runtime_get_sync(dev->dev);
dev->slave = slave;
dev->smr = AT91_TWI_SMR_SADR(slave->addr);
at91_init_twi_bus(dev);
at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_SVACC);
dev_info(dev->dev, "entered slave mode (ADR=%d)\n", slave->addr);
return 0;
}
static int at91_unreg_slave(struct i2c_client *slave)
{
struct at91_twi_dev *dev = i2c_get_adapdata(slave->adapter);
WARN_ON(!dev->slave);
dev_info(dev->dev, "leaving slave mode\n");
dev->slave = NULL;
dev->smr = 0;
at91_init_twi_bus(dev);
pm_runtime_put(dev->dev);
return 0;
}
static u32 at91_twi_func(struct i2c_adapter *adapter)
{
return I2C_FUNC_SLAVE | I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL
| I2C_FUNC_SMBUS_READ_BLOCK_DATA;
}
static const struct i2c_algorithm at91_twi_algorithm_slave = {
.reg_slave = at91_reg_slave,
.unreg_slave = at91_unreg_slave,
.functionality = at91_twi_func,
};
int at91_twi_probe_slave(struct platform_device *pdev,
u32 phy_addr, struct at91_twi_dev *dev)
{
int rc;
rc = devm_request_irq(&pdev->dev, dev->irq, atmel_twi_interrupt_slave,
0, dev_name(dev->dev), dev);
if (rc) {
dev_err(dev->dev, "Cannot get irq %d: %d\n", dev->irq, rc);
return rc;
}
dev->adapter.algo = &at91_twi_algorithm_slave;
return 0;
}
void at91_init_twi_bus_slave(struct at91_twi_dev *dev)
{
at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_MSDIS);
if (dev->slave_detected && dev->smr) {
at91_twi_write(dev, AT91_TWI_SMR, dev->smr);
at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SVEN);
}
}
|
