Russell King | 8d91cba | 2007-03-04 20:40:50 +0000 | [diff] [blame] | 1 | /* |
| 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 | */ |
| 34 | static u_int force_ones; |
| 35 | |
| 36 | static 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 | |
| 51 | static 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 | |
| 66 | static int ioc_getscl(void *data) |
| 67 | { |
| 68 | return (ioc_readb(IOC_CONTROL) & SCL) != 0; |
| 69 | } |
| 70 | |
| 71 | static int ioc_getsda(void *data) |
| 72 | { |
| 73 | return (ioc_readb(IOC_CONTROL) & SDA) != 0; |
| 74 | } |
| 75 | |
| 76 | static 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 | |
| 85 | static struct i2c_adapter ioc_ops = { |
| 86 | .id = I2C_HW_B_IOC, |
| 87 | .algo_data = &ioc_data, |
| 88 | }; |
| 89 | |
| 90 | static 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 Viro | 2a9915c | 2007-07-15 21:37:16 +0100 | [diff] [blame] | 97 | module_init(i2c_ioc_init); |