[IA64] add driver for ACPI methods to call native firmware

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 <[e-mail]>
Signed-off-by: Len Brown <[e-mail]>
Signed-off-by: Tony Luck <[e-mail]>

arch/ia64/Kconfig

···
 	  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

arch/ia64/hp/common/Makefile

···
 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

arch/ia64/hp/common/aml_nfw.c

···
+/*
+ * OpRegion handler to allow AML to call native firmware
+ *
+ * (c) Copyright 2007 Hewlett-Packard Development Company, L.P.
+ *	Bjorn Helgaas <[e-mail]>
+ *
+ * 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 <[e-mail]>");
+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);