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