tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * ARM IOC/IOMD i2c driver.
3 *
4 * Copyright (C) 2000 Russell King
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * On Acorn machines, the following i2c devices are on the bus:
11 * - PCF8583 real time clock & static RAM
12 */
13#include <linux/module.h>
14#include <linux/i2c.h>
15#include <linux/i2c-algo-bit.h>
16#include <linux/io.h>
17
18#include <mach/hardware.h>
19#include <asm/hardware/ioc.h>
20
21#define FORCE_ONES 0xdc
22#define SCL 0x02
23#define SDA 0x01
24
25/*
26 * We must preserve all non-i2c output bits in IOC_CONTROL.
27 * Note also that we need to preserve the value of SCL and
28 * SDA outputs as well (which may be different from the
29 * values read back from IOC_CONTROL).
30 */
31static u_int force_ones;
32
33static void ioc_setscl(void *data, int state)
34{
35 u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
36 u_int ones = force_ones;
37
38 if (state)
39 ones |= SCL;
40 else
41 ones &= ~SCL;
42
43 force_ones = ones;
44
45 ioc_writeb(ioc_control | ones, IOC_CONTROL);
46}
47
48static void ioc_setsda(void *data, int state)
49{
50 u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
51 u_int ones = force_ones;
52
53 if (state)
54 ones |= SDA;
55 else
56 ones &= ~SDA;
57
58 force_ones = ones;
59
60 ioc_writeb(ioc_control | ones, IOC_CONTROL);
61}
62
63static int ioc_getscl(void *data)
64{
65 return (ioc_readb(IOC_CONTROL) & SCL) != 0;
66}
67
68static int ioc_getsda(void *data)
69{
70 return (ioc_readb(IOC_CONTROL) & SDA) != 0;
71}
72
73static struct i2c_algo_bit_data ioc_data = {
74 .setsda = ioc_setsda,
75 .setscl = ioc_setscl,
76 .getsda = ioc_getsda,
77 .getscl = ioc_getscl,
78 .udelay = 80,
79 .timeout = HZ,
80};
81
82static struct i2c_adapter ioc_ops = {
83 .nr = 0,
84 .algo_data = &ioc_data,
85};
86
87static int __init i2c_ioc_init(void)
88{
89 force_ones = FORCE_ONES | SCL | SDA;
90
91 return i2c_bit_add_numbered_bus(&ioc_ops);
92}
93
94module_init(i2c_ioc_init);
95
96MODULE_AUTHOR("Russell King <linux@armlinux.org.uk>");
97MODULE_DESCRIPTION("ARM IOC/IOMD i2c driver");
98MODULE_LICENSE("GPL v2");