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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 */
15#include <linux/init.h>
16#include <linux/i2c.h>
17#include <linux/i2c-algo-bit.h>
18
19#include <asm/hardware.h>
20#include <asm/io.h>
21#include <asm/hardware/ioc.h>
22#include <asm/system.h>
23
24#define FORCE_ONES 0xdc
25#define SCL 0x02
26#define SDA 0x01
27
28/*
29 * We must preserve all non-i2c output bits in IOC_CONTROL.
30 * Note also that we need to preserve the value of SCL and
31 * SDA outputs as well (which may be different from the
32 * values read back from IOC_CONTROL).
33 */
34static u_int force_ones;
35
36static void ioc_setscl(void *data, int state)
37{
38 u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
39 u_int ones = force_ones;
40
41 if (state)
42 ones |= SCL;
43 else
44 ones &= ~SCL;
45
46 force_ones = ones;
47
48 ioc_writeb(ioc_control | ones, IOC_CONTROL);
49}
50
51static void ioc_setsda(void *data, int state)
52{
53 u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
54 u_int ones = force_ones;
55
56 if (state)
57 ones |= SDA;
58 else
59 ones &= ~SDA;
60
61 force_ones = ones;
62
63 ioc_writeb(ioc_control | ones, IOC_CONTROL);
64}
65
66static int ioc_getscl(void *data)
67{
68 return (ioc_readb(IOC_CONTROL) & SCL) != 0;
69}
70
71static int ioc_getsda(void *data)
72{
73 return (ioc_readb(IOC_CONTROL) & SDA) != 0;
74}
75
76static struct i2c_algo_bit_data ioc_data = {
77 .setsda = ioc_setsda,
78 .setscl = ioc_setscl,
79 .getsda = ioc_getsda,
80 .getscl = ioc_getscl,
81 .udelay = 80,
82 .timeout = 100
83};
84
85static struct i2c_adapter ioc_ops = {
86 .id = I2C_HW_B_IOC,
87 .algo_data = &ioc_data,
88};
89
90static int __init i2c_ioc_init(void)
91{
92 force_ones = FORCE_ONES | SCL | SDA;
93
94 return i2c_bit_add_bus(&ioc_ops);
95}
96
Al Viro2a9915c2007-07-15 21:37:16 +010097module_init(i2c_ioc_init);