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// SPDX-License-Identifier: GPL-2.0-only
/*
* OpRegion handler to allow AML to call native firmware
*
* (c) Copyright 2007 Hewlett-Packard Development Company, L.P.
* Bjorn Helgaas <bjorn.helgaas@hp.com>
*
* This driver implements HP Open Source Review Board proposal 1842,
* which was approved on 9/20/2006.
*
* For technical documentation, see the HP SPPA Firmware EAS, Appendix F.
*
* ACPI does not define a mechanism for AML methods to call native firmware
* interfaces such as PAL or SAL. This OpRegion handler adds such a mechanism.
* After the handler is installed, an AML method can call native firmware by
* storing the arguments and firmware entry point to specific offsets in the
* OpRegion. When AML reads the "return value" offset from the OpRegion, this
* handler loads up the arguments, makes the firmware call, and returns the
* result.
*/
#include <linux/module.h>
#include <linux/acpi.h>
#include <asm/sal.h>
MODULE_AUTHOR("Bjorn Helgaas <bjorn.helgaas@hp.com>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("ACPI opregion handler for native firmware calls");
static bool force_register;
module_param_named(force, force_register, bool, 0);
MODULE_PARM_DESC(force, "Install opregion handler even without HPQ5001 device");
#define AML_NFW_SPACE 0xA1
struct ia64_pdesc {
void *ip;
void *gp;
};
/*
* N.B. The layout of this structure is defined in the HP SPPA FW EAS, and
* the member offsets are embedded in AML methods.
*/
struct ia64_nfw_context {
u64 arg[8];
struct ia64_sal_retval ret;
u64 ip;
u64 gp;
u64 pad[2];
};
static void *virt_map(u64 address)
{
if (address & (1UL << 63))
return (void *) (__IA64_UNCACHED_OFFSET | address);
return __va(address);
}
static void aml_nfw_execute(struct ia64_nfw_context *c)
{
struct ia64_pdesc virt_entry;
ia64_sal_handler entry;
virt_entry.ip = virt_map(c->ip);
virt_entry.gp = virt_map(c->gp);
entry = (ia64_sal_handler) &virt_entry;
IA64_FW_CALL(entry, c->ret,
c->arg[0], c->arg[1], c->arg[2], c->arg[3],
c->arg[4], c->arg[5], c->arg[6], c->arg[7]);
}
static void aml_nfw_read_arg(u8 *offset, u32 bit_width, u64 *value)
{
switch (bit_width) {
case 8:
*value = *(u8 *)offset;
break;
case 16:
*value = *(u16 *)offset;
break;
case 32:
*value = *(u32 *)offset;
break;
case 64:
*value = *(u64 *)offset;
break;
}
}
static void aml_nfw_write_arg(u8 *offset, u32 bit_width, u64 *value)
{
switch (bit_width) {
case 8:
*(u8 *) offset = *value;
break;
case 16:
*(u16 *) offset = *value;
break;
case 32:
*(u32 *) offset = *value;
break;
case 64:
*(u64 *) offset = *value;
break;
}
}
static acpi_status aml_nfw_handler(u32 function, acpi_physical_address address,
u32 bit_width, u64 *value, void *handler_context,
void *region_context)
{
struct ia64_nfw_context *context = handler_context;
u8 *offset = (u8 *) context + address;
if (bit_width != 8 && bit_width != 16 &&
bit_width != 32 && bit_width != 64)
return AE_BAD_PARAMETER;
if (address + (bit_width >> 3) > sizeof(struct ia64_nfw_context))
return AE_BAD_PARAMETER;
switch (function) {
case ACPI_READ:
if (address == offsetof(struct ia64_nfw_context, ret))
aml_nfw_execute(context);
aml_nfw_read_arg(offset, bit_width, value);
break;
case ACPI_WRITE:
aml_nfw_write_arg(offset, bit_width, value);
break;
}
return AE_OK;
}
static struct ia64_nfw_context global_context;
static int global_handler_registered;
static int aml_nfw_add_global_handler(void)
{
acpi_status status;
if (global_handler_registered)
return 0;
status = acpi_install_address_space_handler(ACPI_ROOT_OBJECT,
AML_NFW_SPACE, aml_nfw_handler, NULL, &global_context);
if (ACPI_FAILURE(status))
return -ENODEV;
global_handler_registered = 1;
printk(KERN_INFO "Global 0x%02X opregion handler registered\n",
AML_NFW_SPACE);
return 0;
}
static int aml_nfw_remove_global_handler(void)
{
acpi_status status;
if (!global_handler_registered)
return 0;
status = acpi_remove_address_space_handler(ACPI_ROOT_OBJECT,
AML_NFW_SPACE, aml_nfw_handler);
if (ACPI_FAILURE(status))
return -ENODEV;
global_handler_registered = 0;
printk(KERN_INFO "Global 0x%02X opregion handler removed\n",
AML_NFW_SPACE);
return 0;
}
static int aml_nfw_add(struct acpi_device *device)
{
/*
* We would normally allocate a new context structure and install
* the address space handler for the specific device we found.
* But the HP-UX implementation shares a single global context
* and always puts the handler at the root, so we'll do the same.
*/
return aml_nfw_add_global_handler();
}
static int aml_nfw_remove(struct acpi_device *device)
{
return aml_nfw_remove_global_handler();
}
static const struct acpi_device_id aml_nfw_ids[] = {
{"HPQ5001", 0},
{"", 0}
};
static struct acpi_driver acpi_aml_nfw_driver = {
.name = "native firmware",
.ids = aml_nfw_ids,
.ops = {
.add = aml_nfw_add,
.remove = aml_nfw_remove,
},
};
static int __init aml_nfw_init(void)
{
int result;
if (force_register)
aml_nfw_add_global_handler();
result = acpi_bus_register_driver(&acpi_aml_nfw_driver);
if (result < 0) {
aml_nfw_remove_global_handler();
return result;
}
return 0;
}
static void __exit aml_nfw_exit(void)
{
acpi_bus_unregister_driver(&acpi_aml_nfw_driver);
aml_nfw_remove_global_handler();
}
module_init(aml_nfw_init);
module_exit(aml_nfw_exit);
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