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
24static u32		bcm_smc_buffer_phys;	/* physical address */
25static void __iomem	*bcm_smc_buffer;	/* virtual address */
26
27struct 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
36static 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 */
43int __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 */
109static 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#ifdef REQUIRES_SEC
129		".arch_extension sec\n"
130#endif
131		"	smc    #0\n"
132		: "=r" (ip), "=r" (r0)
133		: "r" (r4), "r" (r5), "r" (r6)
134		: "r1", "r2", "r3", "r7", "lr");
135
136	BUG_ON(ip != SEC_EXIT_NORMAL);
137
138	return r0;
139}
140
141/* __bcm_kona_smc() should only run on CPU 0, with pre-emption disabled */
142static void __bcm_kona_smc(void *info)
143{
144	struct bcm_kona_smc_data *data = info;
145	u32 *args = bcm_smc_buffer;
146
147	BUG_ON(smp_processor_id() != 0);
148	BUG_ON(!args);
149
150	/* Copy the four 32 bit argument values into the bounce area */
151	writel_relaxed(data->arg0, args++);
152	writel_relaxed(data->arg1, args++);
153	writel_relaxed(data->arg2, args++);
154	writel(data->arg3, args);
155
156	/* Flush caches for input data passed to Secure Monitor */
157	flush_cache_all();
158
159	/* Trap into Secure Monitor and record the request result */
160	data->result = bcm_kona_do_smc(data->service_id, bcm_smc_buffer_phys);
161}
162
163unsigned bcm_kona_smc(unsigned service_id, unsigned arg0, unsigned arg1,
164		  unsigned arg2, unsigned arg3)
165{
166	struct bcm_kona_smc_data data;
167
168	data.service_id = service_id;
169	data.arg0 = arg0;
170	data.arg1 = arg1;
171	data.arg2 = arg2;
172	data.arg3 = arg3;
173	data.result = 0;
174
175	/*
176	 * Due to a limitation of the secure monitor, we must use the SMP
177	 * infrastructure to forward all secure monitor calls to Core 0.
178	 */
179	smp_call_function_single(0, __bcm_kona_smc, &data, 1);
180
181	return data.result;
182}
183