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	of_node_put(node);
58	if (!prop_val)
59		return -EINVAL;
60
61	/* We assume space for four 32-bit arguments */
62	if (prop_size < 4 * sizeof(u32) || prop_size > (u64)ULONG_MAX)
63		return -EINVAL;
64	buffer_size = (unsigned long)prop_size;
65
66	buffer_phys = be32_to_cpup(prop_val);
67	if (!buffer_phys)
68		return -EINVAL;
69
70	bcm_smc_buffer = ioremap(buffer_phys, buffer_size);
71	if (!bcm_smc_buffer)
72		return -ENOMEM;
73	bcm_smc_buffer_phys = buffer_phys;
74
75	pr_info("Kona Secure API initialized\n");
76
77	return 0;
78}
79
80/*
81 * int bcm_kona_do_smc(u32 service_id, u32 buffer_addr)
82 *
83 * Only core 0 can run the secure monitor code.  If an "smc" request
84 * is initiated on a different core it must be redirected to core 0
85 * for execution.  We rely on the caller to handle this.
86 *
87 * Each "smc" request supplies a service id and the address of a
88 * buffer containing parameters related to the service to be
89 * performed.  A flags value defines the behavior of the level 2
90 * cache and interrupt handling while the secure monitor executes.
91 *
92 * Parameters to the "smc" request are passed in r4-r6 as follows:
93 *     r4	service id
94 *     r5	flags (SEC_ROM_*)
95 *     r6	physical address of buffer with other parameters
96 *
97 * Execution of an "smc" request produces two distinct results.
98 *
99 * First, the secure monitor call itself (regardless of the specific
100 * service request) can succeed, or can produce an error.  When an
101 * "smc" request completes this value is found in r12; it should
102 * always be SEC_EXIT_NORMAL.
103 *
104 * In addition, the particular service performed produces a result.
105 * The values that should be expected depend on the service.  We
106 * therefore return this value to the caller, so it can handle the
107 * request result appropriately.  This result value is found in r0
108 * when the "smc" request completes.
109 */
110static int bcm_kona_do_smc(u32 service_id, u32 buffer_phys)
111{
112	register u32 ip asm("ip");	/* Also called r12 */
113	register u32 r0 asm("r0");
114	register u32 r4 asm("r4");
115	register u32 r5 asm("r5");
116	register u32 r6 asm("r6");
117
118	r4 = service_id;
119	r5 = 0x3;		/* Keep IRQ and FIQ off in SM */
120	r6 = buffer_phys;
121
122	asm volatile (
123		/* Make sure we got the registers we want */
124		__asmeq("%0", "ip")
125		__asmeq("%1", "r0")
126		__asmeq("%2", "r4")
127		__asmeq("%3", "r5")
128		__asmeq("%4", "r6")
129		".arch_extension sec\n"
130		"	smc    #0\n"
131		: "=r" (ip), "=r" (r0)
132		: "r" (r4), "r" (r5), "r" (r6)
133		: "r1", "r2", "r3", "r7", "lr");
134
135	BUG_ON(ip != SEC_EXIT_NORMAL);
136
137	return r0;
138}
139
140/* __bcm_kona_smc() should only run on CPU 0, with pre-emption disabled */
141static void __bcm_kona_smc(void *info)
142{
143	struct bcm_kona_smc_data *data = info;
144	u32 __iomem *args = bcm_smc_buffer;
145
146	BUG_ON(smp_processor_id() != 0);
147	BUG_ON(!args);
148
149	/* Copy the four 32 bit argument values into the bounce area */
150	writel_relaxed(data->arg0, args++);
151	writel_relaxed(data->arg1, args++);
152	writel_relaxed(data->arg2, args++);
153	writel(data->arg3, args);
154
155	/* Flush caches for input data passed to Secure Monitor */
156	flush_cache_all();
157
158	/* Trap into Secure Monitor and record the request result */
159	data->result = bcm_kona_do_smc(data->service_id, bcm_smc_buffer_phys);
160}
161
162unsigned bcm_kona_smc(unsigned service_id, unsigned arg0, unsigned arg1,
163		  unsigned arg2, unsigned arg3)
164{
165	struct bcm_kona_smc_data data;
166
167	data.service_id = service_id;
168	data.arg0 = arg0;
169	data.arg1 = arg1;
170	data.arg2 = arg2;
171	data.arg3 = arg3;
172	data.result = 0;
173
174	/*
175	 * Due to a limitation of the secure monitor, we must use the SMP
176	 * infrastructure to forward all secure monitor calls to Core 0.
177	 */
178	smp_call_function_single(0, __bcm_kona_smc, &data, 1);
179
180	return data.result;
181}
182