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
14 #include <stdarg.h>
15 #include <linux/smp.h>
16 #include <linux/io.h>
17 #include <linux/ioport.h>
18
19 #include <asm/cacheflush.h>
20 #include <linux/of_address.h>
21
22 #include "bcm_kona_smc.h"
23
24 static u32 bcm_smc_buffer_phys; /* physical address */
25 static void __iomem *bcm_smc_buffer; /* virtual address */
26
27 struct bcm_kona_smc_data {
28 unsigned service_id;
29 unsigned arg0;
30 unsigned arg1;
31 unsigned arg2;
32 unsigned arg3;
33 unsigned result;
34 };
35
36 static const struct of_device_id bcm_kona_smc_ids[] __initconst = {
37 {.compatible = "brcm,kona-smc"},
38 {.compatible = "bcm,kona-smc"}, /* deprecated name */
39 {},
40 };
41
42 /* Map in the args buffer area */
43 int __init bcm_kona_smc_init(void)
44 {
45 struct device_node *node;
46 const __be32 *prop_val;
47 u64 prop_size = 0;
48 unsigned long buffer_size;
49 u32 buffer_phys;
50
51 /* Read buffer addr and size from the device tree node */
52 node = of_find_matching_node(NULL, bcm_kona_smc_ids);
53 if (!node)
54 return -ENODEV;
55
56 prop_val = of_get_address(node, 0, &prop_size, NULL);
57 if (!prop_val)
58 return -EINVAL;
59
60 /* We assume space for four 32-bit arguments */
61 if (prop_size < 4 * sizeof(u32) || prop_size > (u64)ULONG_MAX)
62 return -EINVAL;
63 buffer_size = (unsigned long)prop_size;
64
65 buffer_phys = be32_to_cpup(prop_val);
66 if (!buffer_phys)
67 return -EINVAL;
68
69 bcm_smc_buffer = ioremap(buffer_phys, buffer_size);
70 if (!bcm_smc_buffer)
71 return -ENOMEM;
72 bcm_smc_buffer_phys = buffer_phys;
73
74 pr_info("Kona Secure API initialized\n");
75
76 return 0;
77 }
78
79 /*
80 * int bcm_kona_do_smc(u32 service_id, u32 buffer_addr)
81 *
82 * Only core 0 can run the secure monitor code. If an "smc" request
83 * is initiated on a different core it must be redirected to core 0
84 * for execution. We rely on the caller to handle this.
85 *
86 * Each "smc" request supplies a service id and the address of a
87 * buffer containing parameters related to the service to be
88 * performed. A flags value defines the behavior of the level 2
89 * cache and interrupt handling while the secure monitor executes.
90 *
91 * Parameters to the "smc" request are passed in r4-r6 as follows:
92 * r4 service id
93 * r5 flags (SEC_ROM_*)
94 * r6 physical address of buffer with other parameters
95 *
96 * Execution of an "smc" request produces two distinct results.
97 *
98 * First, the secure monitor call itself (regardless of the specific
99 * service request) can succeed, or can produce an error. When an
100 * "smc" request completes this value is found in r12; it should
101 * always be SEC_EXIT_NORMAL.
102 *
103 * In addition, the particular service performed produces a result.
104 * The values that should be expected depend on the service. We
105 * therefore return this value to the caller, so it can handle the
106 * request result appropriately. This result value is found in r0
107 * when the "smc" request completes.
108 */
109 static int bcm_kona_do_smc(u32 service_id, u32 buffer_phys)
110 {
111 register u32 ip asm("ip"); /* Also called r12 */
112 register u32 r0 asm("r0");
113 register u32 r4 asm("r4");
114 register u32 r5 asm("r5");
115 register u32 r6 asm("r6");
116
117 r4 = service_id;
118 r5 = 0x3; /* Keep IRQ and FIQ off in SM */
119 r6 = buffer_phys;
120
121 asm volatile (
122 /* Make sure we got the registers we want */
123 __asmeq("%0", "ip")
124 __asmeq("%1", "r0")
125 __asmeq("%2", "r4")
126 __asmeq("%3", "r5")
127 __asmeq("%4", "r6")
128 ".arch_extension sec\n"
129 " smc #0\n"
130 : "=r" (ip), "=r" (r0)
131 : "r" (r4), "r" (r5), "r" (r6)
132 : "r1", "r2", "r3", "r7", "lr");
133
134 BUG_ON(ip != SEC_EXIT_NORMAL);
135
136 return r0;
137 }
138
139 /* __bcm_kona_smc() should only run on CPU 0, with pre-emption disabled */
140 static void __bcm_kona_smc(void *info)
141 {
142 struct bcm_kona_smc_data *data = info;
143 u32 *args = bcm_smc_buffer;
144
145 BUG_ON(smp_processor_id() != 0);
146 BUG_ON(!args);
147
148 /* Copy the four 32 bit argument values into the bounce area */
149 writel_relaxed(data->arg0, args++);
150 writel_relaxed(data->arg1, args++);
151 writel_relaxed(data->arg2, args++);
152 writel(data->arg3, args);
153
154 /* Flush caches for input data passed to Secure Monitor */
155 flush_cache_all();
156
157 /* Trap into Secure Monitor and record the request result */
158 data->result = bcm_kona_do_smc(data->service_id, bcm_smc_buffer_phys);
159 }
160
161 unsigned bcm_kona_smc(unsigned service_id, unsigned arg0, unsigned arg1,
162 unsigned arg2, unsigned arg3)
163 {
164 struct bcm_kona_smc_data data;
165
166 data.service_id = service_id;
167 data.arg0 = arg0;
168 data.arg1 = arg1;
169 data.arg2 = arg2;
170 data.arg3 = arg3;
171 data.result = 0;
172
173 /*
174 * Due to a limitation of the secure monitor, we must use the SMP
175 * infrastructure to forward all secure monitor calls to Core 0.
176 */
177 smp_call_function_single(0, __bcm_kona_smc, &data, 1);
178
179 return data.result;
180 }