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IBM Real-Time "SMI Free" mode driver -v7
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After a period of RFC for this driver, I think it is ready
for inclusion in the platform-driver-x86 tree, hopefully to
be staged in the next merge window into Linus's tree.

--Vernon

------------------------------------------------------------

IBM Real-Time "SMI Free" mode driver

This driver supports the Real-Time Linux (RTL) BIOS feature.
The RTL feature allows non-fatal System Management Interrupts
(SMIs) to be disabled on supported IBM platforms and is
intended to be coupled with a user-space daemon to monitor
the hardware in a way that can be prioritized and scheduled
to better suit the requirements for the system.

The Device is presented as a special "_RTL_" table to the OS
in the Extended BIOS Data Area.  There is a simple protocol
for entering and exiting the mode at runtime.  This driver
creates a simple sysfs interface to allow a simple entry and
exit from RTL mode in the UFI/BIOS.

Since the driver is specific to IBM SystemX hardware (x86-
based servers) it only builds on x86 builds.  To reduce the
risk of loading on the wrong hardware, the module uses DMI
information and checks a list of servers that are known to
work.

Signed-off-by: Vernon Mauery <vernux@us.ibm.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>
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Vernon Mauery authored and Matthew Garrett committed Oct 21, 2010
1 parent 260586d commit 35f0ce0
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22 changes: 22 additions & 0 deletions Documentation/ABI/testing/sysfs-devices-system-ibm-rtl
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What: state
Date: Sep 2010
KernelVersion: 2.6.37
Contact: Vernon Mauery <vernux@us.ibm.com>
Description: The state file allows a means by which to change in and
out of Premium Real-Time Mode (PRTM), as well as the
ability to query the current state.
0 => PRTM off
1 => PRTM enabled
Users: The ibm-prtm userspace daemon uses this interface.


What: version
Date: Sep 2010
KernelVersion: 2.6.37
Contact: Vernon Mauery <vernux@us.ibm.com>
Description: The version file provides a means by which to query
the RTL table version that lives in the Extended
BIOS Data Area (EBDA).
Users: The ibm-prtm userspace daemon uses this interface.


16 changes: 16 additions & 0 deletions drivers/platform/x86/Kconfig
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Expand Up @@ -615,6 +615,22 @@ config INTEL_IPS
functionality. If in doubt, say Y here; it will only load on
supported platforms.

config IBM_RTL
tristate "Device driver to enable PRTL support"
depends on X86 && PCI
---help---
Enable support for IBM Premium Real Time Mode (PRTM).
This module will allow you the enter and exit PRTM in the BIOS via
sysfs on platforms that support this feature. System in PRTM will
not receive CPU-generated SMIs for recoverable errors. Use of this
feature without proper support may void your hardware warranty.

If the proper BIOS support is found the driver will load and create
/sys/devices/system/ibm_rtl/. The "state" variable will indicate
whether or not the BIOS is in PRTM.
state = 0 (BIOS SMIs on)
state = 1 (BIOS SMIs off)

config XO1_RFKILL
tristate "OLPC XO-1 software RF kill switch"
depends on OLPC
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2 changes: 1 addition & 1 deletion drivers/platform/x86/Makefile
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Expand Up @@ -32,4 +32,4 @@ obj-$(CONFIG_RAR_REGISTER) += intel_rar_register.o
obj-$(CONFIG_INTEL_IPS) += intel_ips.o
obj-$(CONFIG_GPIO_INTEL_PMIC) += intel_pmic_gpio.o
obj-$(CONFIG_XO1_RFKILL) += xo1-rfkill.o

obj-$(CONFIG_IBM_RTL) += ibm_rtl.o
341 changes: 341 additions & 0 deletions drivers/platform/x86/ibm_rtl.c
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/*
* IBM Real-Time Linux driver
*
* 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* Copyright (C) IBM Corporation, 2010
*
* Author: Keith Mannthey <kmannth@us.ibm.com>
* Vernon Mauery <vernux@us.ibm.com>
*
*/

#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/sysdev.h>
#include <linux/dmi.h>
#include <linux/mutex.h>
#include <asm/bios_ebda.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_LICENSE("GPL");
MODULE_AUTHOR("Keith Mannthey <kmmanth@us.ibm.com>");
MODULE_AUTHOR("Vernon Mauery <vernux@us.ibm.com>");

#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(A, ...) do { \
if (debug) \
pr_info("ibm-rtl: " A, ##__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;
static u32 cmd_port_val;

RTL_DEBUG("%s(%d)\n", __FUNCTION__, 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("ibm-rtl: 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 sysdev_class * dev,
struct sysdev_class_attribute *attr,
char *buf)
{
return sprintf(buf, "%d\n", (int)ioread8(&rtl_table->version));
}

static ssize_t rtl_show_state(struct sysdev_class *dev,
struct sysdev_class_attribute *attr,
char *buf)
{
return sprintf(buf, "%d\n", ioread8(&rtl_table->rt_status));
}

static ssize_t rtl_set_state(struct sysdev_class *dev,
struct sysdev_class_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 struct sysdev_class class_rtl = {
.name = "ibm_rtl",
};

static SYSDEV_CLASS_ATTR(version, S_IRUGO, rtl_show_version, NULL);
static SYSDEV_CLASS_ATTR(state, 0600, rtl_show_state, rtl_set_state);

static struct sysdev_class_attribute *rtl_attributes[] = {
&attr_version,
&attr_state,
NULL
};


static int rtl_setup_sysfs(void) {
int ret, i;
ret = sysdev_class_register(&class_rtl);

if (!ret) {
for (i = 0; rtl_attributes[i]; i ++)
sysdev_class_create_file(&class_rtl, rtl_attributes[i]);
}
return ret;
}

static void rtl_teardown_sysfs(void) {
int i;
for (i = 0; rtl_attributes[i]; i ++)
sysdev_class_remove_file(&class_rtl, rtl_attributes[i]);
sysdev_class_unregister(&class_rtl);
}

static int dmi_check_cb(const struct dmi_system_id *id)
{
RTL_DEBUG("found IBM server '%s'\n", id->ident);
return 0;
}

#define ibm_dmi_entry(NAME, TYPE) \
{ \
.ident = NAME, \
.matches = { \
DMI_MATCH(DMI_SYS_VENDOR, "IBM"), \
DMI_MATCH(DMI_PRODUCT_NAME, TYPE), \
}, \
.callback = dmi_check_cb \
}

static struct dmi_system_id __initdata ibm_rtl_dmi_table[] = {
ibm_dmi_entry("BladeCenter LS21", "7971"),
ibm_dmi_entry("BladeCenter LS22", "7901"),
ibm_dmi_entry("BladeCenter HS21 XM", "7995"),
ibm_dmi_entry("BladeCenter HS22", "7870"),
ibm_dmi_entry("BladeCenter HS22V", "7871"),
ibm_dmi_entry("System x3550 M2", "7946"),
ibm_dmi_entry("System x3650 M2", "7947"),
ibm_dmi_entry("System x3550 M3", "7944"),
ibm_dmi_entry("System x3650 M3", "7945"),
{ }
};

static int __init ibm_rtl_init(void) {
unsigned long ebda_addr, ebda_size;
unsigned int ebda_kb;
int ret = -ENODEV, i;

if (force)
pr_warning("ibm-rtl: module loaded by force\n");
/* first ensure that we are running on IBM HW */
else if (!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 %#llx\n", (u64)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", addr);
plen = rtl_cmd_width/sizeof(char);
rtl_cmd_addr = rtl_port_map(addr, plen);
RTL_DEBUG("rtl_cmd_addr = %#llx\n", (u64)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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