Re: [patch 2/2] ia64: add driver for ACPI methods to call native firmware

[Len Brown <lenb@kernel.org>]

I guess x86 does this via SMI,
I don't see any other way, so it looks reasonable to me.

Tony,
Acked-by: Len Brown <len.brown@intel.com>

On Thursday 20 September 2007 16:22, Bjorn Helgaas wrote:
> This driver for HPQ5001 devices installs a global ACPI OpRegion handler.
> AML methods can use this OpRegion to call native firmware entry points.
> 
> 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.
> 
> Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
> 
> Index: work2/arch/ia64/Kconfig
> ===================================================================
> --- work2.orig/arch/ia64/Kconfig	2007-09-19 10:09:43.000000000 -0600
> +++ work2/arch/ia64/Kconfig	2007-09-19 10:51:15.000000000 -0600
> @@ -461,6 +461,16 @@
>  	  firmware extensions, such as the ability to inject memory-errors
>  	  for test-purposes.  If you're unsure, say N.
>  
> +config IA64_HP_AML_NFW
> +	bool "Support ACPI AML calls to native firmware"
> +	help
> +	  This driver installs a global ACPI Operation Region handler for
> +	  region 0xA1.  AML methods can use this OpRegion to call arbitrary
> +	  native firmware functions.  The driver installs the OpRegion
> +	  handler if there is an HPQ5001 device or if the user supplies
> +	  the "force" module parameter, e.g., with the "aml_nfw.force"
> +	  kernel command line option.
> +
>  source "drivers/sn/Kconfig"
>  
>  config KEXEC
> Index: work2/arch/ia64/hp/common/Makefile
> ===================================================================
> --- work2.orig/arch/ia64/hp/common/Makefile	2007-09-19 10:09:43.000000000 -0600
> +++ work2/arch/ia64/hp/common/Makefile	2007-09-19 10:51:15.000000000 -0600
> @@ -8,3 +8,4 @@
>  obj-y := sba_iommu.o
>  obj-$(CONFIG_IA64_HP_ZX1_SWIOTLB) += hwsw_iommu.o
>  obj-$(CONFIG_IA64_GENERIC) += hwsw_iommu.o
> +obj-$(CONFIG_IA64_HP_AML_NFW) += aml_nfw.o
> Index: work2/arch/ia64/hp/common/aml_nfw.c
> ===================================================================
> --- /dev/null	1970-01-01 00:00:00.000000000 +0000
> +++ work2/arch/ia64/hp/common/aml_nfw.c	2007-09-20 14:05:21.000000000 -0600
> @@ -0,0 +1,236 @@
> +/*
> + * 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 program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * 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 <acpi/acpi_bus.h>
> +#include <acpi/acpi_drivers.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 int 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, acpi_integer *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, acpi_integer *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, acpi_integer *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, int type)
> +{
> +	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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