1/*
2 * OpRegion handler to allow AML to call native firmware
3 *
4 * (c) Copyright 2007 Hewlett-Packard Development Company, L.P.
5 *	Bjorn Helgaas <bjorn.helgaas@hp.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 * This driver implements HP Open Source Review Board proposal 1842,
12 * which was approved on 9/20/2006.
13 *
14 * For technical documentation, see the HP SPPA Firmware EAS, Appendix F.
15 *
16 * ACPI does not define a mechanism for AML methods to call native firmware
17 * interfaces such as PAL or SAL.  This OpRegion handler adds such a mechanism.
18 * After the handler is installed, an AML method can call native firmware by
19 * storing the arguments and firmware entry point to specific offsets in the
20 * OpRegion.  When AML reads the "return value" offset from the OpRegion, this
21 * handler loads up the arguments, makes the firmware call, and returns the
22 * result.
23 */
24
25#include <linux/module.h>
26#include <linux/acpi.h>
27#include <asm/sal.h>
28
29MODULE_AUTHOR("Bjorn Helgaas <bjorn.helgaas@hp.com>");
30MODULE_LICENSE("GPL");
31MODULE_DESCRIPTION("ACPI opregion handler for native firmware calls");
32
33static bool force_register;
34module_param_named(force, force_register, bool, 0);
35MODULE_PARM_DESC(force, "Install opregion handler even without HPQ5001 device");
36
37#define AML_NFW_SPACE		0xA1
38
39struct ia64_pdesc {
40	void *ip;
41	void *gp;
42};
43
44/*
45 * N.B.  The layout of this structure is defined in the HP SPPA FW EAS, and
46 *	 the member offsets are embedded in AML methods.
47 */
48struct ia64_nfw_context {
49	u64 arg[8];
50	struct ia64_sal_retval ret;
51	u64 ip;
52	u64 gp;
53	u64 pad[2];
54};
55
56static void *virt_map(u64 address)
57{
58	if (address & (1UL << 63))
59		return (void *) (__IA64_UNCACHED_OFFSET | address);
60
61	return __va(address);
62}
63
64static void aml_nfw_execute(struct ia64_nfw_context *c)
65{
66	struct ia64_pdesc virt_entry;
67	ia64_sal_handler entry;
68
69	virt_entry.ip = virt_map(c->ip);
70	virt_entry.gp = virt_map(c->gp);
71
72	entry = (ia64_sal_handler) &virt_entry;
73
74	IA64_FW_CALL(entry, c->ret,
75		     c->arg[0], c->arg[1], c->arg[2], c->arg[3],
76		     c->arg[4], c->arg[5], c->arg[6], c->arg[7]);
77}
78
79static void aml_nfw_read_arg(u8 *offset, u32 bit_width, u64 *value)
80{
81	switch (bit_width) {
82	case 8:
83		*value = *(u8 *)offset;
84		break;
85	case 16:
86		*value = *(u16 *)offset;
87		break;
88	case 32:
89		*value = *(u32 *)offset;
90		break;
91	case 64:
92		*value = *(u64 *)offset;
93		break;
94	}
95}
96
97static void aml_nfw_write_arg(u8 *offset, u32 bit_width, u64 *value)
98{
99	switch (bit_width) {
100	case 8:
101		*(u8 *) offset = *value;
102		break;
103	case 16:
104		*(u16 *) offset = *value;
105		break;
106	case 32:
107		*(u32 *) offset = *value;
108		break;
109	case 64:
110		*(u64 *) offset = *value;
111		break;
112	}
113}
114
115static acpi_status aml_nfw_handler(u32 function, acpi_physical_address address,
116	u32 bit_width, u64 *value, void *handler_context,
117	void *region_context)
118{
119	struct ia64_nfw_context *context = handler_context;
120	u8 *offset = (u8 *) context + address;
121
122	if (bit_width !=  8 && bit_width != 16 &&
123	    bit_width != 32 && bit_width != 64)
124		return AE_BAD_PARAMETER;
125
126	if (address + (bit_width >> 3) > sizeof(struct ia64_nfw_context))
127		return AE_BAD_PARAMETER;
128
129	switch (function) {
130	case ACPI_READ:
131		if (address == offsetof(struct ia64_nfw_context, ret))
132			aml_nfw_execute(context);
133		aml_nfw_read_arg(offset, bit_width, value);
134		break;
135	case ACPI_WRITE:
136		aml_nfw_write_arg(offset, bit_width, value);
137		break;
138	}
139
140	return AE_OK;
141}
142
143static struct ia64_nfw_context global_context;
144static int global_handler_registered;
145
146static int aml_nfw_add_global_handler(void)
147{
148	acpi_status status;
149
150	if (global_handler_registered)
151		return 0;
152
153	status = acpi_install_address_space_handler(ACPI_ROOT_OBJECT,
154		AML_NFW_SPACE, aml_nfw_handler, NULL, &global_context);
155	if (ACPI_FAILURE(status))
156		return -ENODEV;
157
158	global_handler_registered = 1;
159	printk(KERN_INFO "Global 0x%02X opregion handler registered\n",
160		AML_NFW_SPACE);
161	return 0;
162}
163
164static int aml_nfw_remove_global_handler(void)
165{
166	acpi_status status;
167
168	if (!global_handler_registered)
169		return 0;
170
171	status = acpi_remove_address_space_handler(ACPI_ROOT_OBJECT,
172		AML_NFW_SPACE, aml_nfw_handler);
173	if (ACPI_FAILURE(status))
174		return -ENODEV;
175
176	global_handler_registered = 0;
177	printk(KERN_INFO "Global 0x%02X opregion handler removed\n",
178		AML_NFW_SPACE);
179	return 0;
180}
181
182static int aml_nfw_add(struct acpi_device *device)
183{
184	/*
185	 * We would normally allocate a new context structure and install
186	 * the address space handler for the specific device we found.
187	 * But the HP-UX implementation shares a single global context
188	 * and always puts the handler at the root, so we'll do the same.
189	 */
190	return aml_nfw_add_global_handler();
191}
192
193static int aml_nfw_remove(struct acpi_device *device)
194{
195	return aml_nfw_remove_global_handler();
196}
197
198static const struct acpi_device_id aml_nfw_ids[] = {
199	{"HPQ5001", 0},
200	{"", 0}
201};
202
203static struct acpi_driver acpi_aml_nfw_driver = {
204	.name = "native firmware",
205	.ids = aml_nfw_ids,
206	.ops = {
207		.add = aml_nfw_add,
208		.remove = aml_nfw_remove,
209		},
210};
211
212static int __init aml_nfw_init(void)
213{
214	int result;
215
216	if (force_register)
217		aml_nfw_add_global_handler();
218
219	result = acpi_bus_register_driver(&acpi_aml_nfw_driver);
220	if (result < 0) {
221		aml_nfw_remove_global_handler();
222		return result;
223	}
224
225	return 0;
226}
227
228static void __exit aml_nfw_exit(void)
229{
230	acpi_bus_unregister_driver(&acpi_aml_nfw_driver);
231	aml_nfw_remove_global_handler();
232}
233
234module_init(aml_nfw_init);
235module_exit(aml_nfw_exit);
236