// SPDX-License-Identifier: GPL-2.0-or-later
/*
* IBM Real-Time Linux driver
*
* Copyright (C) IBM Corporation, 2010
*
* Author: Keith Mannthey <[email protected]>
* Vernon Mauery <[email protected]>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/dmi.h>
#include <linux/efi.h>
#include <linux/mutex.h>
#include <asm/bios_ebda.h>
#include <linux/io-64-nonatomic-lo-hi.h>
static bool force;
module_param(force, bool, 0);
MODULE_PARM_DESC(force, "Force driver load, ignore DMI data");
static bool debug;
module_param(debug, bool, 0644);
MODULE_PARM_DESC(debug, "Show debug output");
MODULE_DESCRIPTION("IBM Premium Real Time Mode (PRTM) driver");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Keith Mannthey <[email protected]>");
MODULE_AUTHOR("Vernon Mauery <[email protected]>");
#define RTL_ADDR_TYPE_IO 1
#define RTL_ADDR_TYPE_MMIO 2
#define RTL_CMD_ENTER_PRTM 1
#define RTL_CMD_EXIT_PRTM 2
/* The RTL table as presented by the EBDA: */
struct ibm_rtl_table {
char signature[5]; /* signature should be "_RTL_" */
u8 version;
u8 rt_status;
u8 command;
u8 command_status;
u8 cmd_address_type;
u8 cmd_granularity;
u8 cmd_offset;
u16 reserve1;
u32 cmd_port_address; /* platform dependent address */
u32 cmd_port_value; /* platform dependent value */
} __attribute__((packed));
/* to locate "_RTL_" signature do a masked 5-byte integer compare */
#define RTL_SIGNATURE 0x0000005f4c54525fULL
#define RTL_MASK 0x000000ffffffffffULL
#define RTL_DEBUG(fmt, ...) \
do { \
if (debug) \
pr_info(fmt, ##__VA_ARGS__); \
} while (0)
static DEFINE_MUTEX(rtl_lock);
static struct ibm_rtl_table __iomem *rtl_table;
static void __iomem *ebda_map;
static void __iomem *rtl_cmd_addr;
static u8 rtl_cmd_type;
static u8 rtl_cmd_width;
static void __iomem *rtl_port_map(phys_addr_t addr, unsigned long len)
{
if (rtl_cmd_type == RTL_ADDR_TYPE_MMIO)
return ioremap(addr, len);
return ioport_map(addr, len);
}
static void rtl_port_unmap(void __iomem *addr)
{
if (addr && rtl_cmd_type == RTL_ADDR_TYPE_MMIO)
iounmap(addr);
else
ioport_unmap(addr);
}
static int ibm_rtl_write(u8 value)
{
int ret = 0, count = 0;
u32 cmd_port_val;
RTL_DEBUG("%s(%d)\n", __func__, value);
value = value == 1 ? RTL_CMD_ENTER_PRTM : RTL_CMD_EXIT_PRTM;
mutex_lock(&rtl_lock);
if (ioread8(&rtl_table->rt_status) != value) {
iowrite8(value, &rtl_table->command);
switch (rtl_cmd_width) {
case 8:
cmd_port_val = ioread8(&rtl_table->cmd_port_value);
RTL_DEBUG("cmd_port_val = %u\n", cmd_port_val);
iowrite8((u8)cmd_port_val, rtl_cmd_addr);
break;
case 16:
cmd_port_val = ioread16(&rtl_table->cmd_port_value);
RTL_DEBUG("cmd_port_val = %u\n", cmd_port_val);
iowrite16((u16)cmd_port_val, rtl_cmd_addr);
break;
case 32:
cmd_port_val = ioread32(&rtl_table->cmd_port_value);
RTL_DEBUG("cmd_port_val = %u\n", cmd_port_val);
iowrite32(cmd_port_val, rtl_cmd_addr);
break;
}
while (ioread8(&rtl_table->command)) {
msleep(10);
if (count++ > 500) {
pr_err("Hardware not responding to "
"mode switch request\n");
ret = -EIO;
break;
}
}
if (ioread8(&rtl_table->command_status)) {
RTL_DEBUG("command_status reports failed command\n");
ret = -EIO;
}
}
mutex_unlock(&rtl_lock);
return ret;
}
static ssize_t rtl_show_version(struct device *dev,
struct device_attribute *attr,
char *buf)
{
return sprintf(buf, "%d\n", (int)ioread8(&rtl_table->version));
}
static ssize_t rtl_show_state(struct device *dev,
struct device_attribute *attr,
char *buf)
{
return sprintf(buf, "%d\n", ioread8(&rtl_table->rt_status));
}
static ssize_t rtl_set_state(struct device *dev,
struct device_attribute *attr,
const char *buf,
size_t count)
{
ssize_t ret;
if (count < 1 || count > 2)
return -EINVAL;
switch (buf[0]) {
case '0':
ret = ibm_rtl_write(0);
break;
case '1':
ret = ibm_rtl_write(1);
break;
default:
ret = -EINVAL;
}
if (ret >= 0)
ret = count;
return ret;
}
static const struct bus_type rtl_subsys = {
.name = "ibm_rtl",
.dev_name = "ibm_rtl",
};
static DEVICE_ATTR(version, S_IRUGO, rtl_show_version, NULL);
static DEVICE_ATTR(state, 0600, rtl_show_state, rtl_set_state);
static struct device_attribute *rtl_attributes[] = {
&dev_attr_version,
&dev_attr_state,
NULL
};
static int rtl_setup_sysfs(void) {
int ret, i;
ret = subsys_system_register(&rtl_subsys, NULL);
if (!ret) {
struct device *dev_root = bus_get_dev_root(&rtl_subsys);
if (dev_root) {
for (i = 0; rtl_attributes[i]; i ++)
device_create_file(dev_root, rtl_attributes[i]);
put_device(dev_root);
}
}
return ret;
}
static void rtl_teardown_sysfs(void) {
struct device *dev_root = bus_get_dev_root(&rtl_subsys);
int i;
if (dev_root) {
for (i = 0; rtl_attributes[i]; i ++)
device_remove_file(dev_root, rtl_attributes[i]);
put_device(dev_root);
}
bus_unregister(&rtl_subsys);
}
static const struct dmi_system_id ibm_rtl_dmi_table[] __initconst = {
{ \
.matches = { \
DMI_MATCH(DMI_SYS_VENDOR, "IBM"), \
}, \
},
{ }
};
static int __init ibm_rtl_init(void) {
unsigned long ebda_addr, ebda_size;
unsigned int ebda_kb;
int ret = -ENODEV, i;
if (force)
pr_warn("module loaded by force\n");
/* first ensure that we are running on IBM HW */
else if (efi_enabled(EFI_BOOT) || !dmi_check_system(ibm_rtl_dmi_table))
return -ENODEV;
/* Get the address for the Extended BIOS Data Area */
ebda_addr = get_bios_ebda();
if (!ebda_addr) {
RTL_DEBUG("no BIOS EBDA found\n");
return -ENODEV;
}
ebda_map = ioremap(ebda_addr, 4);
if (!ebda_map)
return -ENOMEM;
/* First word in the EDBA is the Size in KB */
ebda_kb = ioread16(ebda_map);
RTL_DEBUG("EBDA is %d kB\n", ebda_kb);
if (ebda_kb == 0)
goto out;
iounmap(ebda_map);
ebda_size = ebda_kb*1024;
/* Remap the whole table */
ebda_map = ioremap(ebda_addr, ebda_size);
if (!ebda_map)
return -ENOMEM;
/* search for the _RTL_ signature at the start of the table */
for (i = 0 ; i < ebda_size/sizeof(unsigned int); i++) {
struct ibm_rtl_table __iomem * tmp;
tmp = (struct ibm_rtl_table __iomem *) (ebda_map+i);
if ((readq(&tmp->signature) & RTL_MASK) == RTL_SIGNATURE) {
phys_addr_t addr;
unsigned int plen;
RTL_DEBUG("found RTL_SIGNATURE at %p\n", tmp);
rtl_table = tmp;
/* The address, value, width and offset are platform
* dependent and found in the ibm_rtl_table */
rtl_cmd_width = ioread8(&rtl_table->cmd_granularity);
rtl_cmd_type = ioread8(&rtl_table->cmd_address_type);
RTL_DEBUG("rtl_cmd_width = %u, rtl_cmd_type = %u\n",
rtl_cmd_width, rtl_cmd_type);
addr = ioread32(&rtl_table->cmd_port_address);
RTL_DEBUG("addr = %#llx\n", (unsigned long long)addr);
plen = rtl_cmd_width/sizeof(char);
rtl_cmd_addr = rtl_port_map(addr, plen);
RTL_DEBUG("rtl_cmd_addr = %p\n", rtl_cmd_addr);
if (!rtl_cmd_addr) {
ret = -ENOMEM;
break;
}
ret = rtl_setup_sysfs();
break;
}
}
out:
if (ret) {
iounmap(ebda_map);
rtl_port_unmap(rtl_cmd_addr);
}
return ret;
}
static void __exit ibm_rtl_exit(void)
{
if (rtl_table) {
RTL_DEBUG("cleaning up");
/* do not leave the machine in SMI-free mode */
ibm_rtl_write(0);
/* unmap, unlink and remove all traces */
rtl_teardown_sysfs();
iounmap(ebda_map);
rtl_port_unmap(rtl_cmd_addr);
}
}
module_init(ibm_rtl_init);
module_exit(ibm_rtl_exit);
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