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![Matt Fleming](/assets/img/avatar_default.png)
Originally 'efi_enabled' indicated whether a kernel was booted from EFI firmware. Over time its semantics have changed, and it now indicates whether or not we are booted on an EFI machine with bit-native firmware, e.g. 64-bit kernel with 64-bit firmware. The immediate motivation for this patch is the bug report at, https://bugs.launchpad.net/ubuntu-cdimage/+bug/1040557 which details how running a platform driver on an EFI machine that is designed to run under BIOS can cause the machine to become bricked. Also, the following report, https://bugzilla.kernel.org/show_bug.cgi?id=47121 details how running said driver can also cause Machine Check Exceptions. Drivers need a new means of detecting whether they're running on an EFI machine, as sadly the expression, if (!efi_enabled) hasn't been a sufficient condition for quite some time. Users actually want to query 'efi_enabled' for different reasons - what they really want access to is the list of available EFI facilities. For instance, the x86 reboot code needs to know whether it can invoke the ResetSystem() function provided by the EFI runtime services, while the ACPI OSL code wants to know whether the EFI config tables were mapped successfully. There are also checks in some of the platform driver code to simply see if they're running on an EFI machine (which would make it a bad idea to do BIOS-y things). This patch is a prereq for the samsung-laptop fix patch. Cc: David Airlie <airlied@linux.ie> Cc: Corentin Chary <corentincj@iksaif.net> Cc: Matthew Garrett <mjg59@srcf.ucam.org> Cc: Dave Jiang <dave.jiang@intel.com> Cc: Olof Johansson <olof@lixom.net> Cc: Peter Jones <pjones@redhat.com> Cc: Colin Ian King <colin.king@canonical.com> Cc: Steve Langasek <steve.langasek@canonical.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Konrad Rzeszutek Wilk <konrad@kernel.org> Cc: Rafael J. Wysocki <rjw@sisk.pl> Cc: <stable@vger.kernel.org> Signed-off-by: Matt Fleming <matt.fleming@intel.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
328 lines
8.1 KiB
C
328 lines
8.1 KiB
C
/*
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* IBM Real-Time Linux driver
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* Copyright (C) IBM Corporation, 2010
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*
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* Author: Keith Mannthey <kmannth@us.ibm.com>
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* Vernon Mauery <vernux@us.ibm.com>
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*
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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#include <linux/delay.h>
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#include <linux/module.h>
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#include <linux/io.h>
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#include <linux/dmi.h>
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#include <linux/efi.h>
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#include <linux/mutex.h>
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#include <asm/bios_ebda.h>
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#include <asm-generic/io-64-nonatomic-lo-hi.h>
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static bool force;
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module_param(force, bool, 0);
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MODULE_PARM_DESC(force, "Force driver load, ignore DMI data");
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static bool debug;
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module_param(debug, bool, 0644);
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MODULE_PARM_DESC(debug, "Show debug output");
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Keith Mannthey <kmmanth@us.ibm.com>");
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MODULE_AUTHOR("Vernon Mauery <vernux@us.ibm.com>");
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#define RTL_ADDR_TYPE_IO 1
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#define RTL_ADDR_TYPE_MMIO 2
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#define RTL_CMD_ENTER_PRTM 1
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#define RTL_CMD_EXIT_PRTM 2
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/* The RTL table as presented by the EBDA: */
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struct ibm_rtl_table {
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char signature[5]; /* signature should be "_RTL_" */
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u8 version;
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u8 rt_status;
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u8 command;
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u8 command_status;
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u8 cmd_address_type;
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u8 cmd_granularity;
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u8 cmd_offset;
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u16 reserve1;
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u32 cmd_port_address; /* platform dependent address */
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u32 cmd_port_value; /* platform dependent value */
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} __attribute__((packed));
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/* to locate "_RTL_" signature do a masked 5-byte integer compare */
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#define RTL_SIGNATURE 0x0000005f4c54525fULL
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#define RTL_MASK 0x000000ffffffffffULL
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#define RTL_DEBUG(fmt, ...) \
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do { \
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if (debug) \
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pr_info(fmt, ##__VA_ARGS__); \
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} while (0)
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static DEFINE_MUTEX(rtl_lock);
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static struct ibm_rtl_table __iomem *rtl_table;
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static void __iomem *ebda_map;
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static void __iomem *rtl_cmd_addr;
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static u8 rtl_cmd_type;
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static u8 rtl_cmd_width;
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static void __iomem *rtl_port_map(phys_addr_t addr, unsigned long len)
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{
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if (rtl_cmd_type == RTL_ADDR_TYPE_MMIO)
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return ioremap(addr, len);
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return ioport_map(addr, len);
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}
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static void rtl_port_unmap(void __iomem *addr)
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{
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if (addr && rtl_cmd_type == RTL_ADDR_TYPE_MMIO)
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iounmap(addr);
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else
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ioport_unmap(addr);
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}
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static int ibm_rtl_write(u8 value)
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{
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int ret = 0, count = 0;
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static u32 cmd_port_val;
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RTL_DEBUG("%s(%d)\n", __func__, value);
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value = value == 1 ? RTL_CMD_ENTER_PRTM : RTL_CMD_EXIT_PRTM;
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mutex_lock(&rtl_lock);
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if (ioread8(&rtl_table->rt_status) != value) {
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iowrite8(value, &rtl_table->command);
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switch (rtl_cmd_width) {
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case 8:
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cmd_port_val = ioread8(&rtl_table->cmd_port_value);
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RTL_DEBUG("cmd_port_val = %u\n", cmd_port_val);
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iowrite8((u8)cmd_port_val, rtl_cmd_addr);
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break;
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case 16:
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cmd_port_val = ioread16(&rtl_table->cmd_port_value);
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RTL_DEBUG("cmd_port_val = %u\n", cmd_port_val);
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iowrite16((u16)cmd_port_val, rtl_cmd_addr);
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break;
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case 32:
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cmd_port_val = ioread32(&rtl_table->cmd_port_value);
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RTL_DEBUG("cmd_port_val = %u\n", cmd_port_val);
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iowrite32(cmd_port_val, rtl_cmd_addr);
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break;
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}
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while (ioread8(&rtl_table->command)) {
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msleep(10);
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if (count++ > 500) {
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pr_err("Hardware not responding to "
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"mode switch request\n");
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ret = -EIO;
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break;
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}
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}
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if (ioread8(&rtl_table->command_status)) {
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RTL_DEBUG("command_status reports failed command\n");
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ret = -EIO;
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}
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}
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mutex_unlock(&rtl_lock);
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return ret;
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}
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static ssize_t rtl_show_version(struct device *dev,
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struct device_attribute *attr,
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char *buf)
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{
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return sprintf(buf, "%d\n", (int)ioread8(&rtl_table->version));
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}
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static ssize_t rtl_show_state(struct device *dev,
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struct device_attribute *attr,
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char *buf)
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{
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return sprintf(buf, "%d\n", ioread8(&rtl_table->rt_status));
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}
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static ssize_t rtl_set_state(struct device *dev,
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struct device_attribute *attr,
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const char *buf,
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size_t count)
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{
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ssize_t ret;
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if (count < 1 || count > 2)
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return -EINVAL;
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switch (buf[0]) {
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case '0':
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ret = ibm_rtl_write(0);
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break;
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case '1':
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ret = ibm_rtl_write(1);
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break;
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default:
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ret = -EINVAL;
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}
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if (ret >= 0)
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ret = count;
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return ret;
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}
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static struct bus_type rtl_subsys = {
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.name = "ibm_rtl",
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.dev_name = "ibm_rtl",
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};
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static DEVICE_ATTR(version, S_IRUGO, rtl_show_version, NULL);
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static DEVICE_ATTR(state, 0600, rtl_show_state, rtl_set_state);
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static struct device_attribute *rtl_attributes[] = {
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&dev_attr_version,
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&dev_attr_state,
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NULL
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};
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static int rtl_setup_sysfs(void) {
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int ret, i;
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ret = subsys_system_register(&rtl_subsys, NULL);
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if (!ret) {
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for (i = 0; rtl_attributes[i]; i ++)
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device_create_file(rtl_subsys.dev_root, rtl_attributes[i]);
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}
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return ret;
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}
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static void rtl_teardown_sysfs(void) {
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int i;
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for (i = 0; rtl_attributes[i]; i ++)
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device_remove_file(rtl_subsys.dev_root, rtl_attributes[i]);
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bus_unregister(&rtl_subsys);
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}
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static struct dmi_system_id __initdata ibm_rtl_dmi_table[] = {
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{ \
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.matches = { \
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DMI_MATCH(DMI_SYS_VENDOR, "IBM"), \
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}, \
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},
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{ }
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};
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static int __init ibm_rtl_init(void) {
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unsigned long ebda_addr, ebda_size;
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unsigned int ebda_kb;
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int ret = -ENODEV, i;
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if (force)
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pr_warn("module loaded by force\n");
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/* first ensure that we are running on IBM HW */
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else if (efi_enabled(EFI_BOOT) || !dmi_check_system(ibm_rtl_dmi_table))
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return -ENODEV;
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/* Get the address for the Extended BIOS Data Area */
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ebda_addr = get_bios_ebda();
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if (!ebda_addr) {
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RTL_DEBUG("no BIOS EBDA found\n");
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return -ENODEV;
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}
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ebda_map = ioremap(ebda_addr, 4);
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if (!ebda_map)
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return -ENOMEM;
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/* First word in the EDBA is the Size in KB */
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ebda_kb = ioread16(ebda_map);
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RTL_DEBUG("EBDA is %d kB\n", ebda_kb);
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if (ebda_kb == 0)
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goto out;
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iounmap(ebda_map);
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ebda_size = ebda_kb*1024;
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/* Remap the whole table */
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ebda_map = ioremap(ebda_addr, ebda_size);
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if (!ebda_map)
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return -ENOMEM;
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/* search for the _RTL_ signature at the start of the table */
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for (i = 0 ; i < ebda_size/sizeof(unsigned int); i++) {
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struct ibm_rtl_table __iomem * tmp;
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tmp = (struct ibm_rtl_table __iomem *) (ebda_map+i);
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if ((readq(&tmp->signature) & RTL_MASK) == RTL_SIGNATURE) {
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phys_addr_t addr;
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unsigned int plen;
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RTL_DEBUG("found RTL_SIGNATURE at %p\n", tmp);
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rtl_table = tmp;
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/* The address, value, width and offset are platform
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* dependent and found in the ibm_rtl_table */
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rtl_cmd_width = ioread8(&rtl_table->cmd_granularity);
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rtl_cmd_type = ioread8(&rtl_table->cmd_address_type);
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RTL_DEBUG("rtl_cmd_width = %u, rtl_cmd_type = %u\n",
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rtl_cmd_width, rtl_cmd_type);
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addr = ioread32(&rtl_table->cmd_port_address);
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RTL_DEBUG("addr = %#llx\n", (unsigned long long)addr);
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plen = rtl_cmd_width/sizeof(char);
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rtl_cmd_addr = rtl_port_map(addr, plen);
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RTL_DEBUG("rtl_cmd_addr = %p\n", rtl_cmd_addr);
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if (!rtl_cmd_addr) {
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ret = -ENOMEM;
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break;
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}
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ret = rtl_setup_sysfs();
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break;
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}
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}
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out:
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if (ret) {
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iounmap(ebda_map);
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rtl_port_unmap(rtl_cmd_addr);
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}
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return ret;
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}
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static void __exit ibm_rtl_exit(void)
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{
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if (rtl_table) {
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RTL_DEBUG("cleaning up");
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/* do not leave the machine in SMI-free mode */
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ibm_rtl_write(0);
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/* unmap, unlink and remove all traces */
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rtl_teardown_sysfs();
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iounmap(ebda_map);
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rtl_port_unmap(rtl_cmd_addr);
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}
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}
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module_init(ibm_rtl_init);
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module_exit(ibm_rtl_exit);
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