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Russell King8d91cba2007-03-04 20:40:50 +00001/*
2 * linux/drivers/acorn/char/i2c.c
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 * ARM IOC/IOMD i2c driver.
11 *
12 * On Acorn machines, the following i2c devices are on the bus:
13 * - PCF8583 real time clock & static RAM
14 */
Paul Gortmaker66769332014-01-21 16:22:33 -050015#include <linux/module.h>
Russell King8d91cba2007-03-04 20:40:50 +000016#include <linux/i2c.h>
17#include <linux/i2c-algo-bit.h>
Russell King99730222009-03-25 10:21:35 +000018#include <linux/io.h>
Russell King8d91cba2007-03-04 20:40:50 +000019
Russell Kinga09e64f2008-08-05 16:14:15 +010020#include <mach/hardware.h>
Russell King8d91cba2007-03-04 20:40:50 +000021#include <asm/hardware/ioc.h>
Russell King8d91cba2007-03-04 20:40:50 +000022
23#define FORCE_ONES 0xdc
24#define SCL 0x02
25#define SDA 0x01
26
27/*
28 * We must preserve all non-i2c output bits in IOC_CONTROL.
29 * Note also that we need to preserve the value of SCL and
30 * SDA outputs as well (which may be different from the
31 * values read back from IOC_CONTROL).
32 */
33static u_int force_ones;
34
35static void ioc_setscl(void *data, int state)
36{
37 u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
38 u_int ones = force_ones;
39
40 if (state)
41 ones |= SCL;
42 else
43 ones &= ~SCL;
44
45 force_ones = ones;
46
47 ioc_writeb(ioc_control | ones, IOC_CONTROL);
48}
49
50static void ioc_setsda(void *data, int state)
51{
52 u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
53 u_int ones = force_ones;
54
55 if (state)
56 ones |= SDA;
57 else
58 ones &= ~SDA;
59
60 force_ones = ones;
61
62 ioc_writeb(ioc_control | ones, IOC_CONTROL);
63}
64
65static int ioc_getscl(void *data)
66{
67 return (ioc_readb(IOC_CONTROL) & SCL) != 0;
68}
69
70static int ioc_getsda(void *data)
71{
72 return (ioc_readb(IOC_CONTROL) & SDA) != 0;
73}
74
75static struct i2c_algo_bit_data ioc_data = {
76 .setsda = ioc_setsda,
77 .setscl = ioc_setscl,
78 .getsda = ioc_getsda,
79 .getscl = ioc_getscl,
80 .udelay = 80,
Jean Delvare082a4cf2009-02-24 19:19:49 +010081 .timeout = HZ,
Russell King8d91cba2007-03-04 20:40:50 +000082};
83
84static struct i2c_adapter ioc_ops = {
Russell King531660e2009-02-24 19:19:50 +010085 .nr = 0,
Russell King8d91cba2007-03-04 20:40:50 +000086 .algo_data = &ioc_data,
87};
88
89static int __init i2c_ioc_init(void)
90{
91 force_ones = FORCE_ONES | SCL | SDA;
92
Russell King531660e2009-02-24 19:19:50 +010093 return i2c_bit_add_numbered_bus(&ioc_ops);
Russell King8d91cba2007-03-04 20:40:50 +000094}
95
Al Viro2a9915c2007-07-15 21:37:16 +010096module_init(i2c_ioc_init);