1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  ARM IOC/IOMD i2c driver.
4  *
5  *  Copyright (C) 2000 Russell King
6  *
7  *  On Acorn machines, the following i2c devices are on the bus:
8  *	- PCF8583 real time clock & static RAM
9  */
10 #include <linux/module.h>
11 #include <linux/i2c.h>
12 #include <linux/i2c-algo-bit.h>
13 #include <linux/io.h>
14 
15 #include <mach/hardware.h>
16 #include <asm/hardware/ioc.h>
17 
18 #define FORCE_ONES	0xdc
19 #define SCL		0x02
20 #define SDA		0x01
21 
22 /*
23  * We must preserve all non-i2c output bits in IOC_CONTROL.
24  * Note also that we need to preserve the value of SCL and
25  * SDA outputs as well (which may be different from the
26  * values read back from IOC_CONTROL).
27  */
28 static u_int force_ones;
29 
ioc_setscl(void * data,int state)30 static void ioc_setscl(void *data, int state)
31 {
32 	u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
33 	u_int ones = force_ones;
34 
35 	if (state)
36 		ones |= SCL;
37 	else
38 		ones &= ~SCL;
39 
40 	force_ones = ones;
41 
42  	ioc_writeb(ioc_control | ones, IOC_CONTROL);
43 }
44 
ioc_setsda(void * data,int state)45 static void ioc_setsda(void *data, int state)
46 {
47 	u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
48 	u_int ones = force_ones;
49 
50 	if (state)
51 		ones |= SDA;
52 	else
53 		ones &= ~SDA;
54 
55 	force_ones = ones;
56 
57  	ioc_writeb(ioc_control | ones, IOC_CONTROL);
58 }
59 
ioc_getscl(void * data)60 static int ioc_getscl(void *data)
61 {
62 	return (ioc_readb(IOC_CONTROL) & SCL) != 0;
63 }
64 
ioc_getsda(void * data)65 static int ioc_getsda(void *data)
66 {
67 	return (ioc_readb(IOC_CONTROL) & SDA) != 0;
68 }
69 
70 static struct i2c_algo_bit_data ioc_data = {
71 	.setsda		= ioc_setsda,
72 	.setscl		= ioc_setscl,
73 	.getsda		= ioc_getsda,
74 	.getscl		= ioc_getscl,
75 	.udelay		= 80,
76 	.timeout	= HZ,
77 };
78 
79 static struct i2c_adapter ioc_ops = {
80 	.nr			= 0,
81 	.name			= "ioc",
82 	.algo_data		= &ioc_data,
83 };
84 
i2c_ioc_init(void)85 static int __init i2c_ioc_init(void)
86 {
87 	force_ones = FORCE_ONES | SCL | SDA;
88 
89 	return i2c_bit_add_numbered_bus(&ioc_ops);
90 }
91 
92 module_init(i2c_ioc_init);
93 
94 MODULE_AUTHOR("Russell King <linux@armlinux.org.uk>");
95 MODULE_DESCRIPTION("ARM IOC/IOMD i2c driver");
96 MODULE_LICENSE("GPL v2");
97