linux/drivers/video/via/via_i2c.c
Florian Tobias Schandinat e029ab0d02 viafb: reduce I2C timeout and delay
This patch reduces the value for I2C timeout and udelay.
The udelay was reduced to 10 (old: 40) which is still very high as for
standard-mode I2C even 5 should work. This gives a speedup of factor 4
when talking to I2C devices.
The timeout was reduced to 2 (old: 20) which is taken from the radeon
driver so it should work as well. This gives a speedup of factor 10 when
detecting that there is no I2C device we want to talk to.
This causes a huge improvement of device initialization time.

Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Acked-by: Jonathan Corbet <corbet@lwn.net>
Cc: Joseph Chan <JosephChan@via.com.tw>
2010-09-24 02:15:14 +00:00

291 lines
6.9 KiB
C

/*
* Copyright 1998-2009 VIA Technologies, Inc. All Rights Reserved.
* Copyright 2001-2008 S3 Graphics, Inc. All Rights Reserved.
* 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, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTIES OR REPRESENTATIONS; 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.,
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include <linux/platform_device.h>
#include <linux/delay.h>
#include <linux/spinlock.h>
#include <linux/module.h>
#include <linux/via-core.h>
#include <linux/via_i2c.h>
/*
* There can only be one set of these, so there's no point in having
* them be dynamically allocated...
*/
#define VIAFB_NUM_I2C 5
static struct via_i2c_stuff via_i2c_par[VIAFB_NUM_I2C];
struct viafb_dev *i2c_vdev; /* Passed in from core */
static void via_i2c_setscl(void *data, int state)
{
u8 val;
struct via_port_cfg *adap_data = data;
unsigned long flags;
spin_lock_irqsave(&i2c_vdev->reg_lock, flags);
val = via_read_reg(adap_data->io_port, adap_data->ioport_index) & 0xF0;
if (state)
val |= 0x20;
else
val &= ~0x20;
switch (adap_data->type) {
case VIA_PORT_I2C:
val |= 0x01;
break;
case VIA_PORT_GPIO:
val |= 0x80;
break;
default:
printk(KERN_ERR "viafb_i2c: specify wrong i2c type.\n");
}
via_write_reg(adap_data->io_port, adap_data->ioport_index, val);
spin_unlock_irqrestore(&i2c_vdev->reg_lock, flags);
}
static int via_i2c_getscl(void *data)
{
struct via_port_cfg *adap_data = data;
unsigned long flags;
int ret = 0;
spin_lock_irqsave(&i2c_vdev->reg_lock, flags);
if (via_read_reg(adap_data->io_port, adap_data->ioport_index) & 0x08)
ret = 1;
spin_unlock_irqrestore(&i2c_vdev->reg_lock, flags);
return ret;
}
static int via_i2c_getsda(void *data)
{
struct via_port_cfg *adap_data = data;
unsigned long flags;
int ret = 0;
spin_lock_irqsave(&i2c_vdev->reg_lock, flags);
if (via_read_reg(adap_data->io_port, adap_data->ioport_index) & 0x04)
ret = 1;
spin_unlock_irqrestore(&i2c_vdev->reg_lock, flags);
return ret;
}
static void via_i2c_setsda(void *data, int state)
{
u8 val;
struct via_port_cfg *adap_data = data;
unsigned long flags;
spin_lock_irqsave(&i2c_vdev->reg_lock, flags);
val = via_read_reg(adap_data->io_port, adap_data->ioport_index) & 0xF0;
if (state)
val |= 0x10;
else
val &= ~0x10;
switch (adap_data->type) {
case VIA_PORT_I2C:
val |= 0x01;
break;
case VIA_PORT_GPIO:
val |= 0x40;
break;
default:
printk(KERN_ERR "viafb_i2c: specify wrong i2c type.\n");
}
via_write_reg(adap_data->io_port, adap_data->ioport_index, val);
spin_unlock_irqrestore(&i2c_vdev->reg_lock, flags);
}
int viafb_i2c_readbyte(u8 adap, u8 slave_addr, u8 index, u8 *pdata)
{
int ret;
u8 mm1[] = {0x00};
struct i2c_msg msgs[2];
if (!via_i2c_par[adap].is_active)
return -ENODEV;
*pdata = 0;
msgs[0].flags = 0;
msgs[1].flags = I2C_M_RD;
msgs[0].addr = msgs[1].addr = slave_addr / 2;
mm1[0] = index;
msgs[0].len = 1; msgs[1].len = 1;
msgs[0].buf = mm1; msgs[1].buf = pdata;
ret = i2c_transfer(&via_i2c_par[adap].adapter, msgs, 2);
if (ret == 2)
ret = 0;
else if (ret >= 0)
ret = -EIO;
return ret;
}
int viafb_i2c_writebyte(u8 adap, u8 slave_addr, u8 index, u8 data)
{
int ret;
u8 msg[2] = { index, data };
struct i2c_msg msgs;
if (!via_i2c_par[adap].is_active)
return -ENODEV;
msgs.flags = 0;
msgs.addr = slave_addr / 2;
msgs.len = 2;
msgs.buf = msg;
ret = i2c_transfer(&via_i2c_par[adap].adapter, &msgs, 1);
if (ret == 1)
ret = 0;
else if (ret >= 0)
ret = -EIO;
return ret;
}
int viafb_i2c_readbytes(u8 adap, u8 slave_addr, u8 index, u8 *buff, int buff_len)
{
int ret;
u8 mm1[] = {0x00};
struct i2c_msg msgs[2];
if (!via_i2c_par[adap].is_active)
return -ENODEV;
msgs[0].flags = 0;
msgs[1].flags = I2C_M_RD;
msgs[0].addr = msgs[1].addr = slave_addr / 2;
mm1[0] = index;
msgs[0].len = 1; msgs[1].len = buff_len;
msgs[0].buf = mm1; msgs[1].buf = buff;
ret = i2c_transfer(&via_i2c_par[adap].adapter, msgs, 2);
if (ret == 2)
ret = 0;
else if (ret >= 0)
ret = -EIO;
return ret;
}
/*
* Allow other viafb subdevices to look up a specific adapter
* by port name.
*/
struct i2c_adapter *viafb_find_i2c_adapter(enum viafb_i2c_adap which)
{
struct via_i2c_stuff *stuff = &via_i2c_par[which];
return &stuff->adapter;
}
EXPORT_SYMBOL_GPL(viafb_find_i2c_adapter);
static int create_i2c_bus(struct i2c_adapter *adapter,
struct i2c_algo_bit_data *algo,
struct via_port_cfg *adap_cfg,
struct pci_dev *pdev)
{
algo->setsda = via_i2c_setsda;
algo->setscl = via_i2c_setscl;
algo->getsda = via_i2c_getsda;
algo->getscl = via_i2c_getscl;
algo->udelay = 10;
algo->timeout = 2;
algo->data = adap_cfg;
sprintf(adapter->name, "viafb i2c io_port idx 0x%02x",
adap_cfg->ioport_index);
adapter->owner = THIS_MODULE;
adapter->id = 0x01FFFF;
adapter->class = I2C_CLASS_DDC;
adapter->algo_data = algo;
if (pdev)
adapter->dev.parent = &pdev->dev;
else
adapter->dev.parent = NULL;
/* i2c_set_adapdata(adapter, adap_cfg); */
/* Raise SCL and SDA */
via_i2c_setsda(adap_cfg, 1);
via_i2c_setscl(adap_cfg, 1);
udelay(20);
return i2c_bit_add_bus(adapter);
}
static int viafb_i2c_probe(struct platform_device *platdev)
{
int i, ret;
struct via_port_cfg *configs;
i2c_vdev = platdev->dev.platform_data;
configs = i2c_vdev->port_cfg;
for (i = 0; i < VIAFB_NUM_PORTS; i++) {
struct via_port_cfg *adap_cfg = configs++;
struct via_i2c_stuff *i2c_stuff = &via_i2c_par[i];
i2c_stuff->is_active = 0;
if (adap_cfg->type == 0 || adap_cfg->mode != VIA_MODE_I2C)
continue;
ret = create_i2c_bus(&i2c_stuff->adapter,
&i2c_stuff->algo, adap_cfg,
NULL); /* FIXME: PCIDEV */
if (ret < 0) {
printk(KERN_ERR "viafb: cannot create i2c bus %u:%d\n",
i, ret);
continue; /* Still try to make the rest */
}
i2c_stuff->is_active = 1;
}
return 0;
}
static int viafb_i2c_remove(struct platform_device *platdev)
{
int i;
for (i = 0; i < VIAFB_NUM_PORTS; i++) {
struct via_i2c_stuff *i2c_stuff = &via_i2c_par[i];
/*
* Only remove those entries in the array that we've
* actually used (and thus initialized algo_data)
*/
if (i2c_stuff->is_active)
i2c_del_adapter(&i2c_stuff->adapter);
}
return 0;
}
static struct platform_driver via_i2c_driver = {
.driver = {
.name = "viafb-i2c",
},
.probe = viafb_i2c_probe,
.remove = viafb_i2c_remove,
};
int viafb_i2c_init(void)
{
return platform_driver_register(&via_i2c_driver);
}
void viafb_i2c_exit(void)
{
platform_driver_unregister(&via_i2c_driver);
}