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
26 MODULE_AUTHOR("Bjorn Helgaas <bjorn.helgaas@hp.com>");
27 MODULE_LICENSE("GPL");
28 MODULE_DESCRIPTION("ACPI opregion handler for native firmware calls");
29
30 static bool force_register;
31 module_param_named(force, force_register, bool, 0);
32 MODULE_PARM_DESC(force, "Install opregion handler even without HPQ5001 device");
33
34 #define AML_NFW_SPACE 0xA1
35
36 struct 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 */
45 struct 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
virt_map(u64 address)53 static 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
aml_nfw_execute(struct ia64_nfw_context * c)61 static 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
aml_nfw_read_arg(u8 * offset,u32 bit_width,u64 * value)76 static 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
aml_nfw_write_arg(u8 * offset,u32 bit_width,u64 * value)94 static 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
aml_nfw_handler(u32 function,acpi_physical_address address,u32 bit_width,u64 * value,void * handler_context,void * region_context)112 static 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
140 static struct ia64_nfw_context global_context;
141 static int global_handler_registered;
142
aml_nfw_add_global_handler(void)143 static 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
aml_nfw_remove_global_handler(void)161 static 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
aml_nfw_add(struct acpi_device * device)179 static 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
aml_nfw_remove(struct acpi_device * device)190 static void aml_nfw_remove(struct acpi_device *device)
191 {
192 aml_nfw_remove_global_handler();
193 }
194
195 static const struct acpi_device_id aml_nfw_ids[] = {
196 {"HPQ5001", 0},
197 {"", 0}
198 };
199
200 static 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
aml_nfw_init(void)209 static 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
aml_nfw_exit(void)225 static void __exit aml_nfw_exit(void)
226 {
227 acpi_bus_unregister_driver(&acpi_aml_nfw_driver);
228 aml_nfw_remove_global_handler();
229 }
230
231 module_init(aml_nfw_init);
232 module_exit(aml_nfw_exit);
233