xref: /linux/arch/arm/mach-bcm/bcm_kona_smc.c (revision cbd32a1c56e36fedaa93a727699188bd3e6e6f67)
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 }
181