i2c-via.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3    i2c Support for Via Technologies 82C586B South Bridge
  4
  5    Copyright (c) 1998, 1999 Kyösti Mälkki <kmalkki@cc.hut.fi>
  6
  7*/
  8
  9#include <linux/kernel.h>
 10#include <linux/module.h>
 11#include <linux/pci.h>
 12#include <linux/ioport.h>
 13#include <linux/i2c.h>
 14#include <linux/i2c-algo-bit.h>
 15#include <linux/io.h>
 16
 17/* Power management registers */
 18#define PM_CFG_REVID	0x08	/* silicon revision code */
 19#define PM_CFG_IOBASE0	0x20
 20#define PM_CFG_IOBASE1	0x48
 21
 22#define I2C_DIR		(pm_io_base+0x40)
 23#define I2C_OUT		(pm_io_base+0x42)
 24#define I2C_IN		(pm_io_base+0x44)
 25#define I2C_SCL		0x02	/* clock bit in DIR/OUT/IN register */
 26#define I2C_SDA		0x04
 27
 28/* io-region reservation */
 29#define IOSPACE		0x06
 30
 31static struct pci_driver vt586b_driver;
 32static u16 pm_io_base;
 33
 34/*
 35   It does not appear from the datasheet that the GPIO pins are
 36   open drain. So a we set a low value by setting the direction to
 37   output and a high value by setting the direction to input and
 38   relying on the required I2C pullup. The data value is initialized
 39   to 0 in via_init() and never changed.
 40*/
 41static void bit_via_setscl(void *data, int state)
 42{
 43	outb(state ? inb(I2C_DIR) & ~I2C_SCL : inb(I2C_DIR) | I2C_SCL, I2C_DIR);
 44}
 45
 46static void bit_via_setsda(void *data, int state)
 47{
 48	outb(state ? inb(I2C_DIR) & ~I2C_SDA : inb(I2C_DIR) | I2C_SDA, I2C_DIR);
 49}
 50
 51static int bit_via_getscl(void *data)
 52{
 53	return (0 != (inb(I2C_IN) & I2C_SCL));
 54}
 55
 56static int bit_via_getsda(void *data)
 57{
 58	return (0 != (inb(I2C_IN) & I2C_SDA));
 59}
 60
 61
 62static struct i2c_algo_bit_data bit_data = {
 63	.setsda		= bit_via_setsda,
 64	.setscl		= bit_via_setscl,
 65	.getsda		= bit_via_getsda,
 66	.getscl		= bit_via_getscl,
 67	.udelay		= 5,
 68	.timeout	= HZ
 69};
 70
 71static struct i2c_adapter vt586b_adapter = {
 72	.owner		= THIS_MODULE,
 73	.class          = I2C_CLASS_HWMON,
 74	.name		= "VIA i2c",
 75	.algo_data	= &bit_data,
 76};
 77
 78
 79static const struct pci_device_id vt586b_ids[] = {
 80	{ PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_82C586_3) },
 81	{ 0, }
 82};
 83
 84MODULE_DEVICE_TABLE (pci, vt586b_ids);
 85
 86static int vt586b_probe(struct pci_dev *dev, const struct pci_device_id *id)
 87{
 88	u16 base;
 89	u8 rev;
 90	int res;
 91
 92	if (pm_io_base)
 93		return dev_err_probe(&dev->dev, -ENODEV,
 94				     "Will only support one host\n");
 95
 96	pci_read_config_byte(dev, PM_CFG_REVID, &rev);
 97
 98	switch (rev) {
 99	case 0x00:
100		base = PM_CFG_IOBASE0;
101		break;
102	case 0x01:
103	case 0x10:
104		base = PM_CFG_IOBASE1;
105		break;
106
107	default:
108		base = PM_CFG_IOBASE1;
109		/* later revision */
110	}
111
112	pci_read_config_word(dev, base, &pm_io_base);
113	pm_io_base &= (0xff << 8);
114
115	if (!request_region(I2C_DIR, IOSPACE, vt586b_driver.name))
116		return dev_err_probe(&dev->dev, -ENODEV,
117				     "IO 0x%x-0x%x already in use\n",
118				     I2C_DIR, I2C_DIR + IOSPACE);
119
120	outb(inb(I2C_DIR) & ~(I2C_SDA | I2C_SCL), I2C_DIR);
121	outb(inb(I2C_OUT) & ~(I2C_SDA | I2C_SCL), I2C_OUT);
122
123	/* set up the sysfs linkage to our parent device */
124	vt586b_adapter.dev.parent = &dev->dev;
125
126	res = i2c_bit_add_bus(&vt586b_adapter);
127	if ( res < 0 ) {
128		release_region(I2C_DIR, IOSPACE);
129		pm_io_base = 0;
130		return res;
131	}
132	return 0;
133}
134
135static void vt586b_remove(struct pci_dev *dev)
136{
137	i2c_del_adapter(&vt586b_adapter);
138	release_region(I2C_DIR, IOSPACE);
139	pm_io_base = 0;
140}
141
142
143static struct pci_driver vt586b_driver = {
144	.name		= "vt586b_smbus",
145	.id_table	= vt586b_ids,
146	.probe		= vt586b_probe,
147	.remove		= vt586b_remove,
148};
149
150module_pci_driver(vt586b_driver);
151
152MODULE_AUTHOR("Kyösti Mälkki <kmalkki@cc.hut.fi>");
153MODULE_DESCRIPTION("i2c for Via vt82c586b southbridge");
154MODULE_LICENSE("GPL");