diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-parport-light.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-parport-light.c | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-parport-light.c b/drivers/i2c/busses/i2c-parport-light.c new file mode 100644 index 000000000000..cb5e722301d8 --- /dev/null +++ b/drivers/i2c/busses/i2c-parport-light.c @@ -0,0 +1,175 @@ +/* ------------------------------------------------------------------------ * + * i2c-parport.c I2C bus over parallel port * + * ------------------------------------------------------------------------ * + Copyright (C) 2003-2004 Jean Delvare <khali@linux-fr.org> + + Based on older i2c-velleman.c driver + Copyright (C) 1995-2000 Simon G. Vogl + With some changes from: + Frodo Looijaard <frodol@dds.nl> + Kyösti Mälkki <kmalkki@cc.hut.fi> + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + * ------------------------------------------------------------------------ */ + +#include <linux/config.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/init.h> +#include <linux/ioport.h> +#include <linux/i2c.h> +#include <linux/i2c-algo-bit.h> +#include <asm/io.h> +#include "i2c-parport.h" + +#define DEFAULT_BASE 0x378 + +static u16 base; +module_param(base, ushort, 0); +MODULE_PARM_DESC(base, "Base I/O address"); + +/* ----- Low-level parallel port access ----------------------------------- */ + +static inline void port_write(unsigned char p, unsigned char d) +{ + outb(d, base+p); +} + +static inline unsigned char port_read(unsigned char p) +{ + return inb(base+p); +} + +/* ----- Unified line operation functions --------------------------------- */ + +static inline void line_set(int state, const struct lineop *op) +{ + u8 oldval = port_read(op->port); + + /* Touch only the bit(s) needed */ + if ((op->inverted && !state) || (!op->inverted && state)) + port_write(op->port, oldval | op->val); + else + port_write(op->port, oldval & ~op->val); +} + +static inline int line_get(const struct lineop *op) +{ + u8 oldval = port_read(op->port); + + return ((op->inverted && (oldval & op->val) != op->val) + || (!op->inverted && (oldval & op->val) == op->val)); +} + +/* ----- I2C algorithm call-back functions and structures ----------------- */ + +static void parport_setscl(void *data, int state) +{ + line_set(state, &adapter_parm[type].setscl); +} + +static void parport_setsda(void *data, int state) +{ + line_set(state, &adapter_parm[type].setsda); +} + +static int parport_getscl(void *data) +{ + return line_get(&adapter_parm[type].getscl); +} + +static int parport_getsda(void *data) +{ + return line_get(&adapter_parm[type].getsda); +} + +/* Encapsulate the functions above in the correct structure + Note that getscl will be set to NULL by the attaching code for adapters + that cannot read SCL back */ +static struct i2c_algo_bit_data parport_algo_data = { + .setsda = parport_setsda, + .setscl = parport_setscl, + .getsda = parport_getsda, + .getscl = parport_getscl, + .udelay = 50, + .mdelay = 50, + .timeout = HZ, +}; + +/* ----- I2c structure ---------------------------------------------------- */ + +static struct i2c_adapter parport_adapter = { + .owner = THIS_MODULE, + .class = I2C_CLASS_HWMON, + .id = I2C_HW_B_LP, + .algo_data = &parport_algo_data, + .name = "Parallel port adapter (light)", +}; + +/* ----- Module loading, unloading and information ------------------------ */ + +static int __init i2c_parport_init(void) +{ + int type_count; + + type_count = sizeof(adapter_parm)/sizeof(struct adapter_parm); + if (type < 0 || type >= type_count) { + printk(KERN_WARNING "i2c-parport: invalid type (%d)\n", type); + type = 0; + } + + if (base == 0) { + printk(KERN_INFO "i2c-parport: using default base 0x%x\n", DEFAULT_BASE); + base = DEFAULT_BASE; + } + + if (!request_region(base, 3, "i2c-parport")) + return -ENODEV; + + if (!adapter_parm[type].getscl.val) + parport_algo_data.getscl = NULL; + + /* Reset hardware to a sane state (SCL and SDA high) */ + parport_setsda(NULL, 1); + parport_setscl(NULL, 1); + /* Other init if needed (power on...) */ + if (adapter_parm[type].init.val) + line_set(1, &adapter_parm[type].init); + + if (i2c_bit_add_bus(&parport_adapter) < 0) { + printk(KERN_ERR "i2c-parport: Unable to register with I2C\n"); + release_region(base, 3); + return -ENODEV; + } + + return 0; +} + +static void __exit i2c_parport_exit(void) +{ + /* Un-init if needed (power off...) */ + if (adapter_parm[type].init.val) + line_set(0, &adapter_parm[type].init); + + i2c_bit_del_bus(&parport_adapter); + release_region(base, 3); +} + +MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>"); +MODULE_DESCRIPTION("I2C bus over parallel port (light)"); +MODULE_LICENSE("GPL"); + +module_init(i2c_parport_init); +module_exit(i2c_parport_exit); |