98 lines
1.9 KiB
C
98 lines
1.9 KiB
C
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/*
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* linux/drivers/acorn/char/i2c.c
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*
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* Copyright (C) 2000 Russell King
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* ARM IOC/IOMD i2c driver.
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*
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* On Acorn machines, the following i2c devices are on the bus:
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* - PCF8583 real time clock & static RAM
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*/
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#include <linux/init.h>
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#include <linux/i2c.h>
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#include <linux/i2c-algo-bit.h>
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#include <asm/hardware.h>
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#include <asm/io.h>
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#include <asm/hardware/ioc.h>
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#include <asm/system.h>
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#define FORCE_ONES 0xdc
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#define SCL 0x02
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#define SDA 0x01
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/*
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* We must preserve all non-i2c output bits in IOC_CONTROL.
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* Note also that we need to preserve the value of SCL and
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* SDA outputs as well (which may be different from the
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* values read back from IOC_CONTROL).
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*/
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static u_int force_ones;
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static void ioc_setscl(void *data, int state)
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{
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u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
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u_int ones = force_ones;
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if (state)
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ones |= SCL;
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else
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ones &= ~SCL;
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force_ones = ones;
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ioc_writeb(ioc_control | ones, IOC_CONTROL);
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}
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static void ioc_setsda(void *data, int state)
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{
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u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
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u_int ones = force_ones;
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if (state)
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ones |= SDA;
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else
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ones &= ~SDA;
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force_ones = ones;
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ioc_writeb(ioc_control | ones, IOC_CONTROL);
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}
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static int ioc_getscl(void *data)
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{
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return (ioc_readb(IOC_CONTROL) & SCL) != 0;
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}
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static int ioc_getsda(void *data)
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{
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return (ioc_readb(IOC_CONTROL) & SDA) != 0;
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}
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static struct i2c_algo_bit_data ioc_data = {
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.setsda = ioc_setsda,
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.setscl = ioc_setscl,
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.getsda = ioc_getsda,
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.getscl = ioc_getscl,
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.udelay = 80,
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.timeout = 100
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};
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static struct i2c_adapter ioc_ops = {
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.id = I2C_HW_B_IOC,
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.algo_data = &ioc_data,
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};
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static int __init i2c_ioc_init(void)
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{
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force_ones = FORCE_ONES | SCL | SDA;
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return i2c_bit_add_bus(&ioc_ops);
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}
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__initcall(i2c_ioc_init);
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