source: mainline/kernel/arch/arm32/src/cpu/cpu.c@ 22a0ee8

/*
 * Copyright (c) 2007 Michal Kebrt
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup arm32
 * @{
 */
/** @file
 *  @brief CPU identification.
 */

#include <arch/cpu.h>
#include <cpu.h>
#include <arch.h>
#include <print.h>
#include <fpu_context.h>

/** Number of indexes left out in the #imp_data array */
#define IMP_DATA_START_OFFSET 0x40

/** Implementators (vendor) names */
static const char *imp_data[] = {
        "?",                                     /* IMP_DATA_START_OFFSET */
        "ARM Limited",                           /* 0x41 */
        "", "",                                  /* 0x42 - 0x43 */
        "Digital Equipment Corporation",         /* 0x44 */
        "", "", "", "", "", "", "", "",          /* 0x45 - 0x4c */
        "Motorola, Freescale Semicondutor Inc.", /* 0x4d */
        "", "", "",                              /* 0x4e - 0x50 */
        "Qualcomm Inc.",                         /* 0x51 */
        "", "", "", "",                          /* 0x52 - 0x55 */
        "Marvell Semiconductor",                 /* 0x56 */
        "", "", "", "", "", "", "", "", "", "",  /* 0x57 - 0x60 */
        "", "", "", "", "", "", "", "",          /* 0x61 - 0x68 */
        "Intel Corporation"                      /* 0x69 */
};

/** Length of the #imp_data array */
static unsigned int imp_data_length = sizeof(imp_data) / sizeof(char *);

/** Architecture names */
static const char *arch_data[] = {
        "?",       /* 0x0 */
        "4",       /* 0x1 */
        "4T",      /* 0x2 */
        "5",       /* 0x3 */
        "5T",      /* 0x4 */
        "5TE",     /* 0x5 */
        "5TEJ",    /* 0x6 */
        "6"        /* 0x7 */
};

/** Length of the #arch_data array */
static unsigned int arch_data_length = sizeof(arch_data) / sizeof(char *);


/** Retrieves processor identification from CP15 register 0.
 * 
 * @param cpu Structure for storing CPU identification.
 */
static void arch_cpu_identify(cpu_arch_t *cpu)
{
        uint32_t ident;
        asm volatile (
                "mrc p15, 0, %[ident], c0, c0, 0\n"
                : [ident] "=r" (ident)
        );
        
        cpu->imp_num = ident >> 24;
        cpu->variant_num = (ident << 8) >> 28;
        cpu->arch_num = (ident << 12) >> 28;
        cpu->prim_part_num = (ident << 16) >> 20;
        cpu->rev_num = (ident << 28) >> 28;
}

/** Enables unaligned access and caching for armv6+ */
void cpu_arch_init(void)
{
#if defined(PROCESSOR_armv7_a) | defined(PROCESSOR_armv6)
        uint32_t control_reg = 0;
        asm volatile (
                "mrc p15, 0, %[control_reg], c1, c0"
                : [control_reg] "=r" (control_reg)
        );
        
        /* Turn off tex remap, RAZ ignores writes prior to armv7 */
        control_reg &= ~CP15_R1_TEX_REMAP_EN;
        /* Turn off accessed flag, RAZ ignores writes prior to armv7 */
        control_reg &= ~(CP15_R1_ACCESS_FLAG_EN | CP15_R1_HW_ACCESS_FLAG_EN);
        /* Enable unaligned access, RAZ ignores writes prior to armv6
         * switchable on armv6, RAO ignores writes on armv7,
         * see ARM Architecture Reference Manual ARMv7-A and ARMv7-R edition
         * L.3.1 (p. 2456) */
        control_reg |= CP15_R1_UNALIGNED_EN;
        /* Disable alignment checks, this turns unaligned access to undefined,
         * unless U bit is set. */
        control_reg &= ~CP15_R1_ALIGN_CHECK_EN;
        /* Enable caching, On arm prior to armv7 there is only one level
         * of caches. Data cache is coherent.
         * "This means that the behavior of accesses from the same observer to
         * different VAs, that are translated to the same PA
         * with the same memory attributes, is fully coherent."
         *    ARM Architecture Reference Manual ARMv7-A and ARMv7-R Edition
         *    B3.11.1 (p. 1383)
         * ICache coherency is elaborate on in barrier.h.
         * We are safe to turn these on.
         */
        control_reg |= CP15_R1_CACHE_EN | CP15_R1_INST_CACHE_EN;
        
        asm volatile (
                "mcr p15, 0, %[control_reg], c1, c0"
                :: [control_reg] "r" (control_reg)
        );
#endif
}

void fpu_init(void)
{
        //TODO: Identify FPU unit
        //and set correct functions to save/restore ctx
}

void fpu_enable(void)
{
        /* Enable FPU instructions */
        asm volatile (
                "ldr r1, =0x40000000\n"
                "vmsr fpexc, r1\n"
                ::: "r1"
        );
}

void fpu_disable(void)
{
        /* Disable FPU instructions */
        asm volatile (
                "ldr r1, =0x00000000\n"
                "vmsr fpexc, r1\n"
                ::: "r1"
        );
}

void fpu_context_save(fpu_context_t *ctx)
{
        // TODO check and complete. What about fpexc?
        asm volatile (
                "vmrs r1, fpscr\n"
//              "vmrs r2, fpexc\n"
                "stm %0, {r1, r2}\n"
                "vstm %0, {d0, d1, d2, d3, d4, d5, d6, d7, d8, d9, d10, d11, d12, d13, d14, d15}\n"
                ::"r" (ctx): "r1","r2","memory"
        );
}

void fpu_context_restore(fpu_context_t *ctx)
{
        // TODO check and complete. What about fpexc?
        asm volatile (
                "ldm %0, {r1, r2}\n"
                "vmsr fpscr, r1\n"
//              "vmsr fpexc, r2\n"
                "vldm %0, {d0, d1, d2, d3, d4, d5, d6, d7, d8, d9, d10, d11, d12, d13, d14, d15}\n"
                ::"r" (ctx): "r1","r2"
        );
}

/** Retrieves processor identification and stores it to #CPU.arch */
void cpu_identify(void)
{
        arch_cpu_identify(&CPU->arch);
}

/** Prints CPU identification. */
void cpu_print_report(cpu_t *m)
{
        const char *vendor = imp_data[0];
        const char *architecture = arch_data[0];
        cpu_arch_t * cpu_arch = &m->arch;

        const unsigned imp_offset = cpu_arch->imp_num - IMP_DATA_START_OFFSET;

        if (imp_offset < imp_data_length) {
                vendor = imp_data[cpu_arch->imp_num - IMP_DATA_START_OFFSET];
        }

        // TODO CPUs with arch_num == 0xf use CPUID scheme for identification
        if (cpu_arch->arch_num < arch_data_length) {
                architecture = arch_data[cpu_arch->arch_num];
        }

        printf("cpu%d: vendor=%s, architecture=ARM%s, part number=%x, "
            "variant=%x, revision=%x\n",
            m->id, vendor, architecture, cpu_arch->prim_part_num,
            cpu_arch->variant_num, cpu_arch->rev_num);
}

/** @}
 */