18d91cbadSRussell King /* 28d91cbadSRussell King * linux/drivers/acorn/char/i2c.c 38d91cbadSRussell King * 48d91cbadSRussell King * Copyright (C) 2000 Russell King 58d91cbadSRussell King * 68d91cbadSRussell King * This program is free software; you can redistribute it and/or modify 78d91cbadSRussell King * it under the terms of the GNU General Public License version 2 as 88d91cbadSRussell King * published by the Free Software Foundation. 98d91cbadSRussell King * 108d91cbadSRussell King * ARM IOC/IOMD i2c driver. 118d91cbadSRussell King * 128d91cbadSRussell King * On Acorn machines, the following i2c devices are on the bus: 138d91cbadSRussell King * - PCF8583 real time clock & static RAM 148d91cbadSRussell King */ 158d91cbadSRussell King #include <linux/init.h> 168d91cbadSRussell King #include <linux/i2c.h> 178d91cbadSRussell King #include <linux/i2c-algo-bit.h> 188d91cbadSRussell King 198d91cbadSRussell King #include <asm/hardware.h> 208d91cbadSRussell King #include <asm/io.h> 218d91cbadSRussell King #include <asm/hardware/ioc.h> 228d91cbadSRussell King #include <asm/system.h> 238d91cbadSRussell King 248d91cbadSRussell King #define FORCE_ONES 0xdc 258d91cbadSRussell King #define SCL 0x02 268d91cbadSRussell King #define SDA 0x01 278d91cbadSRussell King 288d91cbadSRussell King /* 298d91cbadSRussell King * We must preserve all non-i2c output bits in IOC_CONTROL. 308d91cbadSRussell King * Note also that we need to preserve the value of SCL and 318d91cbadSRussell King * SDA outputs as well (which may be different from the 328d91cbadSRussell King * values read back from IOC_CONTROL). 338d91cbadSRussell King */ 348d91cbadSRussell King static u_int force_ones; 358d91cbadSRussell King 368d91cbadSRussell King static void ioc_setscl(void *data, int state) 378d91cbadSRussell King { 388d91cbadSRussell King u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA); 398d91cbadSRussell King u_int ones = force_ones; 408d91cbadSRussell King 418d91cbadSRussell King if (state) 428d91cbadSRussell King ones |= SCL; 438d91cbadSRussell King else 448d91cbadSRussell King ones &= ~SCL; 458d91cbadSRussell King 468d91cbadSRussell King force_ones = ones; 478d91cbadSRussell King 488d91cbadSRussell King ioc_writeb(ioc_control | ones, IOC_CONTROL); 498d91cbadSRussell King } 508d91cbadSRussell King 518d91cbadSRussell King static void ioc_setsda(void *data, int state) 528d91cbadSRussell King { 538d91cbadSRussell King u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA); 548d91cbadSRussell King u_int ones = force_ones; 558d91cbadSRussell King 568d91cbadSRussell King if (state) 578d91cbadSRussell King ones |= SDA; 588d91cbadSRussell King else 598d91cbadSRussell King ones &= ~SDA; 608d91cbadSRussell King 618d91cbadSRussell King force_ones = ones; 628d91cbadSRussell King 638d91cbadSRussell King ioc_writeb(ioc_control | ones, IOC_CONTROL); 648d91cbadSRussell King } 658d91cbadSRussell King 668d91cbadSRussell King static int ioc_getscl(void *data) 678d91cbadSRussell King { 688d91cbadSRussell King return (ioc_readb(IOC_CONTROL) & SCL) != 0; 698d91cbadSRussell King } 708d91cbadSRussell King 718d91cbadSRussell King static int ioc_getsda(void *data) 728d91cbadSRussell King { 738d91cbadSRussell King return (ioc_readb(IOC_CONTROL) & SDA) != 0; 748d91cbadSRussell King } 758d91cbadSRussell King 768d91cbadSRussell King static struct i2c_algo_bit_data ioc_data = { 778d91cbadSRussell King .setsda = ioc_setsda, 788d91cbadSRussell King .setscl = ioc_setscl, 798d91cbadSRussell King .getsda = ioc_getsda, 808d91cbadSRussell King .getscl = ioc_getscl, 818d91cbadSRussell King .udelay = 80, 828d91cbadSRussell King .timeout = 100 838d91cbadSRussell King }; 848d91cbadSRussell King 858d91cbadSRussell King static struct i2c_adapter ioc_ops = { 868d91cbadSRussell King .id = I2C_HW_B_IOC, 878d91cbadSRussell King .algo_data = &ioc_data, 888d91cbadSRussell King }; 898d91cbadSRussell King 908d91cbadSRussell King static int __init i2c_ioc_init(void) 918d91cbadSRussell King { 928d91cbadSRussell King force_ones = FORCE_ONES | SCL | SDA; 938d91cbadSRussell King 948d91cbadSRussell King return i2c_bit_add_bus(&ioc_ops); 958d91cbadSRussell King } 968d91cbadSRussell King 978d91cbadSRussell King __initcall(i2c_ioc_init); 98