1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * OpRegion handler to allow AML to call native firmware
4 *
5 * (c) Copyright 2007 Hewlett-Packard Development Company, L.P.
6 *	Bjorn Helgaas <bjorn.helgaas@hp.com>
7 *
8 * This driver implements HP Open Source Review Board proposal 1842,
9 * which was approved on 9/20/2006.
10 *
11 * For technical documentation, see the HP SPPA Firmware EAS, Appendix F.
12 *
13 * ACPI does not define a mechanism for AML methods to call native firmware
14 * interfaces such as PAL or SAL.  This OpRegion handler adds such a mechanism.
15 * After the handler is installed, an AML method can call native firmware by
16 * storing the arguments and firmware entry point to specific offsets in the
17 * OpRegion.  When AML reads the "return value" offset from the OpRegion, this
18 * handler loads up the arguments, makes the firmware call, and returns the
19 * result.
20 */
21
22#include <linux/module.h>
23#include <linux/acpi.h>
24#include <asm/sal.h>
25
26MODULE_AUTHOR("Bjorn Helgaas <bjorn.helgaas@hp.com>");
27MODULE_LICENSE("GPL");
28MODULE_DESCRIPTION("ACPI opregion handler for native firmware calls");
29
30static bool force_register;
31module_param_named(force, force_register, bool, 0);
32MODULE_PARM_DESC(force, "Install opregion handler even without HPQ5001 device");
33
34#define AML_NFW_SPACE		0xA1
35
36struct ia64_pdesc {
37	void *ip;
38	void *gp;
39};
40
41/*
42 * N.B.  The layout of this structure is defined in the HP SPPA FW EAS, and
43 *	 the member offsets are embedded in AML methods.
44 */
45struct ia64_nfw_context {
46	u64 arg[8];
47	struct ia64_sal_retval ret;
48	u64 ip;
49	u64 gp;
50	u64 pad[2];
51};
52
53static void *virt_map(u64 address)
54{
55	if (address & (1UL << 63))
56		return (void *) (__IA64_UNCACHED_OFFSET | address);
57
58	return __va(address);
59}
60
61static void aml_nfw_execute(struct ia64_nfw_context *c)
62{
63	struct ia64_pdesc virt_entry;
64	ia64_sal_handler entry;
65
66	virt_entry.ip = virt_map(c->ip);
67	virt_entry.gp = virt_map(c->gp);
68
69	entry = (ia64_sal_handler) &virt_entry;
70
71	IA64_FW_CALL(entry, c->ret,
72		     c->arg[0], c->arg[1], c->arg[2], c->arg[3],
73		     c->arg[4], c->arg[5], c->arg[6], c->arg[7]);
74}
75
76static void aml_nfw_read_arg(u8 *offset, u32 bit_width, u64 *value)
77{
78	switch (bit_width) {
79	case 8:
80		*value = *(u8 *)offset;
81		break;
82	case 16:
83		*value = *(u16 *)offset;
84		break;
85	case 32:
86		*value = *(u32 *)offset;
87		break;
88	case 64:
89		*value = *(u64 *)offset;
90		break;
91	}
92}
93
94static void aml_nfw_write_arg(u8 *offset, u32 bit_width, u64 *value)
95{
96	switch (bit_width) {
97	case 8:
98		*(u8 *) offset = *value;
99		break;
100	case 16:
101		*(u16 *) offset = *value;
102		break;
103	case 32:
104		*(u32 *) offset = *value;
105		break;
106	case 64:
107		*(u64 *) offset = *value;
108		break;
109	}
110}
111
112static acpi_status aml_nfw_handler(u32 function, acpi_physical_address address,
113	u32 bit_width, u64 *value, void *handler_context,
114	void *region_context)
115{
116	struct ia64_nfw_context *context = handler_context;
117	u8 *offset = (u8 *) context + address;
118
119	if (bit_width !=  8 && bit_width != 16 &&
120	    bit_width != 32 && bit_width != 64)
121		return AE_BAD_PARAMETER;
122
123	if (address + (bit_width >> 3) > sizeof(struct ia64_nfw_context))
124		return AE_BAD_PARAMETER;
125
126	switch (function) {
127	case ACPI_READ:
128		if (address == offsetof(struct ia64_nfw_context, ret))
129			aml_nfw_execute(context);
130		aml_nfw_read_arg(offset, bit_width, value);
131		break;
132	case ACPI_WRITE:
133		aml_nfw_write_arg(offset, bit_width, value);
134		break;
135	}
136
137	return AE_OK;
138}
139
140static struct ia64_nfw_context global_context;
141static int global_handler_registered;
142
143static int aml_nfw_add_global_handler(void)
144{
145	acpi_status status;
146
147	if (global_handler_registered)
148		return 0;
149
150	status = acpi_install_address_space_handler(ACPI_ROOT_OBJECT,
151		AML_NFW_SPACE, aml_nfw_handler, NULL, &global_context);
152	if (ACPI_FAILURE(status))
153		return -ENODEV;
154
155	global_handler_registered = 1;
156	printk(KERN_INFO "Global 0x%02X opregion handler registered\n",
157		AML_NFW_SPACE);
158	return 0;
159}
160
161static int aml_nfw_remove_global_handler(void)
162{
163	acpi_status status;
164
165	if (!global_handler_registered)
166		return 0;
167
168	status = acpi_remove_address_space_handler(ACPI_ROOT_OBJECT,
169		AML_NFW_SPACE, aml_nfw_handler);
170	if (ACPI_FAILURE(status))
171		return -ENODEV;
172
173	global_handler_registered = 0;
174	printk(KERN_INFO "Global 0x%02X opregion handler removed\n",
175		AML_NFW_SPACE);
176	return 0;
177}
178
179static int aml_nfw_add(struct acpi_device *device)
180{
181	/*
182	 * We would normally allocate a new context structure and install
183	 * the address space handler for the specific device we found.
184	 * But the HP-UX implementation shares a single global context
185	 * and always puts the handler at the root, so we'll do the same.
186	 */
187	return aml_nfw_add_global_handler();
188}
189
190static int aml_nfw_remove(struct acpi_device *device)
191{
192	return aml_nfw_remove_global_handler();
193}
194
195static const struct acpi_device_id aml_nfw_ids[] = {
196	{"HPQ5001", 0},
197	{"", 0}
198};
199
200static struct acpi_driver acpi_aml_nfw_driver = {
201	.name = "native firmware",
202	.ids = aml_nfw_ids,
203	.ops = {
204		.add = aml_nfw_add,
205		.remove = aml_nfw_remove,
206		},
207};
208
209static int __init aml_nfw_init(void)
210{
211	int result;
212
213	if (force_register)
214		aml_nfw_add_global_handler();
215
216	result = acpi_bus_register_driver(&acpi_aml_nfw_driver);
217	if (result < 0) {
218		aml_nfw_remove_global_handler();
219		return result;
220	}
221
222	return 0;
223}
224
225static void __exit aml_nfw_exit(void)
226{
227	acpi_bus_unregister_driver(&acpi_aml_nfw_driver);
228	aml_nfw_remove_global_handler();
229}
230
231module_init(aml_nfw_init);
232module_exit(aml_nfw_exit);
233