linux/arch/arm/mach-bcm/bcm_kona_smc.c
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   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                ".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 */
 140static void __bcm_kona_smc(void *info)
 141{
 142        struct bcm_kona_smc_data *data = info;
 143        u32 __iomem *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
 161unsigned 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