diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-parport.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-parport.c | 330 |
1 files changed, 330 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-parport.c b/drivers/i2c/busses/i2c-parport.c new file mode 100644 index 000000000..319209a07 --- /dev/null +++ b/drivers/i2c/busses/i2c-parport.c @@ -0,0 +1,330 @@ +/* ------------------------------------------------------------------------ * + * i2c-parport.c I2C bus over parallel port * + * ------------------------------------------------------------------------ * + Copyright (C) 2003-2011 Jean Delvare <jdelvare@suse.de> + + Based on older i2c-philips-par.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. + * ------------------------------------------------------------------------ */ + +#define pr_fmt(fmt) "i2c-parport: " fmt + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/init.h> +#include <linux/delay.h> +#include <linux/parport.h> +#include <linux/i2c.h> +#include <linux/i2c-algo-bit.h> +#include <linux/i2c-smbus.h> +#include <linux/slab.h> +#include <linux/list.h> +#include <linux/mutex.h> +#include "i2c-parport.h" + +/* ----- Device list ------------------------------------------------------ */ + +struct i2c_par { + struct pardevice *pdev; + struct i2c_adapter adapter; + struct i2c_algo_bit_data algo_data; + struct i2c_smbus_alert_setup alert_data; + struct i2c_client *ara; + struct list_head node; +}; + +static LIST_HEAD(adapter_list); +static DEFINE_MUTEX(adapter_list_lock); +#define MAX_DEVICE 4 +static int parport[MAX_DEVICE] = {0, -1, -1, -1}; + + +/* ----- Low-level parallel port access ----------------------------------- */ + +static void port_write_data(struct parport *p, unsigned char d) +{ + parport_write_data(p, d); +} + +static void port_write_control(struct parport *p, unsigned char d) +{ + parport_write_control(p, d); +} + +static unsigned char port_read_data(struct parport *p) +{ + return parport_read_data(p); +} + +static unsigned char port_read_status(struct parport *p) +{ + return parport_read_status(p); +} + +static unsigned char port_read_control(struct parport *p) +{ + return parport_read_control(p); +} + +static void (* const port_write[])(struct parport *, unsigned char) = { + port_write_data, + NULL, + port_write_control, +}; + +static unsigned char (* const port_read[])(struct parport *) = { + port_read_data, + port_read_status, + port_read_control, +}; + +/* ----- Unified line operation functions --------------------------------- */ + +static inline void line_set(struct parport *data, int state, + const struct lineop *op) +{ + u8 oldval = port_read[op->port](data); + + /* Touch only the bit(s) needed */ + if ((op->inverted && !state) || (!op->inverted && state)) + port_write[op->port](data, oldval | op->val); + else + port_write[op->port](data, oldval & ~op->val); +} + +static inline int line_get(struct parport *data, + const struct lineop *op) +{ + u8 oldval = port_read[op->port](data); + + 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((struct parport *) data, state, &adapter_parm[type].setscl); +} + +static void parport_setsda(void *data, int state) +{ + line_set((struct parport *) data, state, &adapter_parm[type].setsda); +} + +static int parport_getscl(void *data) +{ + return line_get((struct parport *) data, &adapter_parm[type].getscl); +} + +static int parport_getsda(void *data) +{ + return line_get((struct parport *) data, &adapter_parm[type].getsda); +} + +/* Encapsulate the functions above in the correct structure. + Note that this is only a template, from which the real structures are + copied. The attaching code will set getscl to NULL for adapters that + cannot read SCL back, and will also make the data field point to + the parallel port structure. */ +static const struct i2c_algo_bit_data parport_algo_data = { + .setsda = parport_setsda, + .setscl = parport_setscl, + .getsda = parport_getsda, + .getscl = parport_getscl, + .udelay = 10, /* ~50 kbps */ + .timeout = HZ, +}; + +/* ----- I2c and parallel port call-back functions and structures --------- */ + +static void i2c_parport_irq(void *data) +{ + struct i2c_par *adapter = data; + struct i2c_client *ara = adapter->ara; + + if (ara) { + dev_dbg(&ara->dev, "SMBus alert received\n"); + i2c_handle_smbus_alert(ara); + } else + dev_dbg(&adapter->adapter.dev, + "SMBus alert received but no ARA client!\n"); +} + +static void i2c_parport_attach(struct parport *port) +{ + struct i2c_par *adapter; + int i; + struct pardev_cb i2c_parport_cb; + + for (i = 0; i < MAX_DEVICE; i++) { + if (parport[i] == -1) + continue; + if (port->number == parport[i]) + break; + } + if (i == MAX_DEVICE) { + pr_debug("Not using parport%d.\n", port->number); + return; + } + + adapter = kzalloc(sizeof(struct i2c_par), GFP_KERNEL); + if (!adapter) + return; + memset(&i2c_parport_cb, 0, sizeof(i2c_parport_cb)); + i2c_parport_cb.flags = PARPORT_FLAG_EXCL; + i2c_parport_cb.irq_func = i2c_parport_irq; + i2c_parport_cb.private = adapter; + + pr_debug("attaching to %s\n", port->name); + parport_disable_irq(port); + adapter->pdev = parport_register_dev_model(port, "i2c-parport", + &i2c_parport_cb, i); + if (!adapter->pdev) { + pr_err("Unable to register with parport\n"); + goto err_free; + } + + /* Fill the rest of the structure */ + adapter->adapter.owner = THIS_MODULE; + adapter->adapter.class = I2C_CLASS_HWMON; + strlcpy(adapter->adapter.name, "Parallel port adapter", + sizeof(adapter->adapter.name)); + adapter->algo_data = parport_algo_data; + /* Slow down if we can't sense SCL */ + if (!adapter_parm[type].getscl.val) { + adapter->algo_data.getscl = NULL; + adapter->algo_data.udelay = 50; /* ~10 kbps */ + } + adapter->algo_data.data = port; + adapter->adapter.algo_data = &adapter->algo_data; + adapter->adapter.dev.parent = port->physport->dev; + + if (parport_claim_or_block(adapter->pdev) < 0) { + dev_err(&adapter->pdev->dev, + "Could not claim parallel port\n"); + goto err_unregister; + } + + /* Reset hardware to a sane state (SCL and SDA high) */ + parport_setsda(port, 1); + parport_setscl(port, 1); + /* Other init if needed (power on...) */ + if (adapter_parm[type].init.val) { + line_set(port, 1, &adapter_parm[type].init); + /* Give powered devices some time to settle */ + msleep(100); + } + + if (i2c_bit_add_bus(&adapter->adapter) < 0) { + dev_err(&adapter->pdev->dev, "Unable to register with I2C\n"); + goto err_unregister; + } + + /* Setup SMBus alert if supported */ + if (adapter_parm[type].smbus_alert) { + adapter->ara = i2c_setup_smbus_alert(&adapter->adapter, + &adapter->alert_data); + if (adapter->ara) + parport_enable_irq(port); + else + dev_warn(&adapter->pdev->dev, + "Failed to register ARA client\n"); + } + + /* Add the new adapter to the list */ + mutex_lock(&adapter_list_lock); + list_add_tail(&adapter->node, &adapter_list); + mutex_unlock(&adapter_list_lock); + return; + + err_unregister: + parport_release(adapter->pdev); + parport_unregister_device(adapter->pdev); + err_free: + kfree(adapter); +} + +static void i2c_parport_detach(struct parport *port) +{ + struct i2c_par *adapter, *_n; + + /* Walk the list */ + mutex_lock(&adapter_list_lock); + list_for_each_entry_safe(adapter, _n, &adapter_list, node) { + if (adapter->pdev->port == port) { + if (adapter->ara) { + parport_disable_irq(port); + i2c_unregister_device(adapter->ara); + } + i2c_del_adapter(&adapter->adapter); + + /* Un-init if needed (power off...) */ + if (adapter_parm[type].init.val) + line_set(port, 0, &adapter_parm[type].init); + + parport_release(adapter->pdev); + parport_unregister_device(adapter->pdev); + list_del(&adapter->node); + kfree(adapter); + } + } + mutex_unlock(&adapter_list_lock); +} + +static struct parport_driver i2c_parport_driver = { + .name = "i2c-parport", + .match_port = i2c_parport_attach, + .detach = i2c_parport_detach, + .devmodel = true, +}; + +/* ----- Module loading, unloading and information ------------------------ */ + +static int __init i2c_parport_init(void) +{ + if (type < 0) { + pr_warn("adapter type unspecified\n"); + return -ENODEV; + } + + if (type >= ARRAY_SIZE(adapter_parm)) { + pr_warn("invalid type (%d)\n", type); + return -ENODEV; + } + + return parport_register_driver(&i2c_parport_driver); +} + +static void __exit i2c_parport_exit(void) +{ + parport_unregister_driver(&i2c_parport_driver); +} + +MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>"); +MODULE_DESCRIPTION("I2C bus over parallel port"); +MODULE_LICENSE("GPL"); + +module_param_array(parport, int, NULL, 0); +MODULE_PARM_DESC(parport, + "List of parallel ports to bind to, by index.\n" + " Atmost " __stringify(MAX_DEVICE) " devices are supported.\n" + " Default is one device connected to parport0.\n" +); + +module_init(i2c_parport_init); +module_exit(i2c_parport_exit); |