1 /*
2 * Copyright (C) 2013 Broadcom Corporation
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation version 2.
7 *
8 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
9 * kind, whether express or implied; without even the implied warranty
10 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 */
13 #include <linux/smp.h>
14 #include <linux/io.h>
15 #include <linux/ioport.h>
16
17 #include <asm/cacheflush.h>
18 #include <linux/of_address.h>
19
20 #include "bcm_kona_smc.h"
21
22 static u32 bcm_smc_buffer_phys; /* physical address */
23 static void __iomem *bcm_smc_buffer; /* virtual address */
24
25 struct bcm_kona_smc_data {
26 unsigned service_id;
27 unsigned arg0;
28 unsigned arg1;
29 unsigned arg2;
30 unsigned arg3;
31 unsigned result;
32 };
33
34 static const struct of_device_id bcm_kona_smc_ids[] __initconst = {
35 {.compatible = "brcm,kona-smc"},
36 {.compatible = "bcm,kona-smc"}, /* deprecated name */
37 {},
38 };
39
40 /* Map in the args buffer area */
bcm_kona_smc_init(void)41 int __init bcm_kona_smc_init(void)
42 {
43 struct device_node *node;
44 const __be32 *prop_val;
45 u64 prop_size = 0;
46 unsigned long buffer_size;
47 u32 buffer_phys;
48
49 /* Read buffer addr and size from the device tree node */
50 node = of_find_matching_node(NULL, bcm_kona_smc_ids);
51 if (!node)
52 return -ENODEV;
53
54 prop_val = of_get_address(node, 0, &prop_size, NULL);
55 of_node_put(node);
56 if (!prop_val)
57 return -EINVAL;
58
59 /* We assume space for four 32-bit arguments */
60 if (prop_size < 4 * sizeof(u32) || prop_size > (u64)ULONG_MAX)
61 return -EINVAL;
62 buffer_size = (unsigned long)prop_size;
63
64 buffer_phys = be32_to_cpup(prop_val);
65 if (!buffer_phys)
66 return -EINVAL;
67
68 bcm_smc_buffer = ioremap(buffer_phys, buffer_size);
69 if (!bcm_smc_buffer)
70 return -ENOMEM;
71 bcm_smc_buffer_phys = buffer_phys;
72
73 pr_info("Kona Secure API initialized\n");
74
75 return 0;
76 }
77
78 /*
79 * int bcm_kona_do_smc(u32 service_id, u32 buffer_addr)
80 *
81 * Only core 0 can run the secure monitor code. If an "smc" request
82 * is initiated on a different core it must be redirected to core 0
83 * for execution. We rely on the caller to handle this.
84 *
85 * Each "smc" request supplies a service id and the address of a
86 * buffer containing parameters related to the service to be
87 * performed. A flags value defines the behavior of the level 2
88 * cache and interrupt handling while the secure monitor executes.
89 *
90 * Parameters to the "smc" request are passed in r4-r6 as follows:
91 * r4 service id
92 * r5 flags (SEC_ROM_*)
93 * r6 physical address of buffer with other parameters
94 *
95 * Execution of an "smc" request produces two distinct results.
96 *
97 * First, the secure monitor call itself (regardless of the specific
98 * service request) can succeed, or can produce an error. When an
99 * "smc" request completes this value is found in r12; it should
100 * always be SEC_EXIT_NORMAL.
101 *
102 * In addition, the particular service performed produces a result.
103 * The values that should be expected depend on the service. We
104 * therefore return this value to the caller, so it can handle the
105 * request result appropriately. This result value is found in r0
106 * when the "smc" request completes.
107 */
bcm_kona_do_smc(u32 service_id,u32 buffer_phys)108 static int bcm_kona_do_smc(u32 service_id, u32 buffer_phys)
109 {
110 register u32 ip asm("ip"); /* Also called r12 */
111 register u32 r0 asm("r0");
112 register u32 r4 asm("r4");
113 register u32 r5 asm("r5");
114 register u32 r6 asm("r6");
115
116 r4 = service_id;
117 r5 = 0x3; /* Keep IRQ and FIQ off in SM */
118 r6 = buffer_phys;
119
120 asm volatile (
121 /* Make sure we got the registers we want */
122 __asmeq("%0", "ip")
123 __asmeq("%1", "r0")
124 __asmeq("%2", "r4")
125 __asmeq("%3", "r5")
126 __asmeq("%4", "r6")
127 ".arch_extension sec\n"
128 " smc #0\n"
129 : "=r" (ip), "=r" (r0)
130 : "r" (r4), "r" (r5), "r" (r6)
131 : "r1", "r2", "r3", "r7", "lr");
132
133 BUG_ON(ip != SEC_EXIT_NORMAL);
134
135 return r0;
136 }
137
138 /* __bcm_kona_smc() should only run on CPU 0, with pre-emption disabled */
__bcm_kona_smc(void * info)139 static void __bcm_kona_smc(void *info)
140 {
141 struct bcm_kona_smc_data *data = info;
142 u32 __iomem *args = bcm_smc_buffer;
143
144 BUG_ON(smp_processor_id() != 0);
145 BUG_ON(!args);
146
147 /* Copy the four 32 bit argument values into the bounce area */
148 writel_relaxed(data->arg0, args++);
149 writel_relaxed(data->arg1, args++);
150 writel_relaxed(data->arg2, args++);
151 writel(data->arg3, args);
152
153 /* Flush caches for input data passed to Secure Monitor */
154 flush_cache_all();
155
156 /* Trap into Secure Monitor and record the request result */
157 data->result = bcm_kona_do_smc(data->service_id, bcm_smc_buffer_phys);
158 }
159
bcm_kona_smc(unsigned service_id,unsigned arg0,unsigned arg1,unsigned arg2,unsigned arg3)160 unsigned bcm_kona_smc(unsigned service_id, unsigned arg0, unsigned arg1,
161 unsigned arg2, unsigned arg3)
162 {
163 struct bcm_kona_smc_data data;
164
165 data.service_id = service_id;
166 data.arg0 = arg0;
167 data.arg1 = arg1;
168 data.arg2 = arg2;
169 data.arg3 = arg3;
170 data.result = 0;
171
172 /*
173 * Due to a limitation of the secure monitor, we must use the SMP
174 * infrastructure to forward all secure monitor calls to Core 0.
175 */
176 smp_call_function_single(0, __bcm_kona_smc, &data, 1);
177
178 return data.result;
179 }
180