1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * ARM IOC/IOMD i2c driver. 4 * 5 * Copyright (C) 2000 Russell King 6 * 7 * On Acorn machines, the following i2c devices are on the bus: 8 * - PCF8583 real time clock & static RAM 9 */ 10 #include <linux/module.h> 11 #include <linux/i2c.h> 12 #include <linux/i2c-algo-bit.h> 13 #include <linux/io.h> 14 15 #include <mach/hardware.h> 16 #include <asm/hardware/ioc.h> 17 18 #define FORCE_ONES 0xdc 19 #define SCL 0x02 20 #define SDA 0x01 21 22 /* 23 * We must preserve all non-i2c output bits in IOC_CONTROL. 24 * Note also that we need to preserve the value of SCL and 25 * SDA outputs as well (which may be different from the 26 * values read back from IOC_CONTROL). 27 */ 28 static u_int force_ones; 29 30 static void ioc_setscl(void *data, int state) 31 { 32 u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA); 33 u_int ones = force_ones; 34 35 if (state) 36 ones |= SCL; 37 else 38 ones &= ~SCL; 39 40 force_ones = ones; 41 42 ioc_writeb(ioc_control | ones, IOC_CONTROL); 43 } 44 45 static void ioc_setsda(void *data, int state) 46 { 47 u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA); 48 u_int ones = force_ones; 49 50 if (state) 51 ones |= SDA; 52 else 53 ones &= ~SDA; 54 55 force_ones = ones; 56 57 ioc_writeb(ioc_control | ones, IOC_CONTROL); 58 } 59 60 static int ioc_getscl(void *data) 61 { 62 return (ioc_readb(IOC_CONTROL) & SCL) != 0; 63 } 64 65 static int ioc_getsda(void *data) 66 { 67 return (ioc_readb(IOC_CONTROL) & SDA) != 0; 68 } 69 70 static struct i2c_algo_bit_data ioc_data = { 71 .setsda = ioc_setsda, 72 .setscl = ioc_setscl, 73 .getsda = ioc_getsda, 74 .getscl = ioc_getscl, 75 .udelay = 80, 76 .timeout = HZ, 77 }; 78 79 static struct i2c_adapter ioc_ops = { 80 .nr = 0, 81 .name = "ioc", 82 .algo_data = &ioc_data, 83 }; 84 85 static int __init i2c_ioc_init(void) 86 { 87 force_ones = FORCE_ONES | SCL | SDA; 88 89 return i2c_bit_add_numbered_bus(&ioc_ops); 90 } 91 92 module_init(i2c_ioc_init); 93 94 MODULE_AUTHOR("Russell King <linux@armlinux.org.uk>"); 95 MODULE_DESCRIPTION("ARM IOC/IOMD i2c driver"); 96 MODULE_LICENSE("GPL v2"); 97