tcm.c

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/*
 * Copyright (C) 2008-2009 ST-Ericsson AB
 * License terms: GNU General Public License (GPL) version 2
 * TCM memory handling for ARM systems
 *
 * Author: Linus Walleij <[email protected]>
 * Author: Rickard Andersson <[email protected]>
 */
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/stddef.h>
#include <linux/ioport.h>
#include <linux/genalloc.h>
#include <linux/string.h> /* memcpy */
#include <asm/cputype.h>
#include <asm/mach/map.h>
#include <asm/memory.h>
#include <asm/system_info.h>
#include "tcm.h"

static struct gen_pool *tcm_pool;
static bool dtcm_present;
static bool itcm_present;

/* TCM section definitions from the linker */
extern char __itcm_start, __sitcm_text, __eitcm_text;
extern char __dtcm_start, __sdtcm_data, __edtcm_data;

/* These will be increased as we run */
u32 dtcm_end = DTCM_OFFSET;
u32 itcm_end = ITCM_OFFSET;

/*
 * TCM memory resources
 */
static struct resource dtcm_res = {
    .name = "DTCM RAM",
    .start = DTCM_OFFSET,
    .end = DTCM_OFFSET,
    .flags = IORESOURCE_MEM
};

static struct resource itcm_res = {
    .name = "ITCM RAM",
    .start = ITCM_OFFSET,
    .end = ITCM_OFFSET,
    .flags = IORESOURCE_MEM
};

static struct map_desc dtcm_iomap[] __initdata = {
    {
        .virtual    = DTCM_OFFSET,
        .pfn        = __phys_to_pfn(DTCM_OFFSET),
        .length     = 0,
        .type       = MT_MEMORY_DTCM
    }
};

static struct map_desc itcm_iomap[] __initdata = {
    {
        .virtual    = ITCM_OFFSET,
        .pfn        = __phys_to_pfn(ITCM_OFFSET),
        .length     = 0,
        .type       = MT_MEMORY_ITCM
    }
};

/*
 * Allocate a chunk of TCM memory
 */
void *tcm_alloc(size_t len)
{
    unsigned long vaddr;

    if (!tcm_pool)
        return NULL;

    vaddr = gen_pool_alloc(tcm_pool, len);
    if (!vaddr)
        return NULL;

    return (void *) vaddr;
}
EXPORT_SYMBOL(tcm_alloc);

/*
 * Free a chunk of TCM memory
 */
void tcm_free(void *addr, size_t len)
{
    gen_pool_free(tcm_pool, (unsigned long) addr, len);
}
EXPORT_SYMBOL(tcm_free);

bool tcm_dtcm_present(void)
{
    return dtcm_present;
}
EXPORT_SYMBOL(tcm_dtcm_present);

bool tcm_itcm_present(void)
{
    return itcm_present;
}
EXPORT_SYMBOL(tcm_itcm_present);

static int __init setup_tcm_bank(u8 type, u8 bank, u8 banks,
                  u32 *offset)
{
    const int tcm_sizes[16] = { 0, -1, -1, 4, 8, 16, 32, 64, 128,
                    256, 512, 1024, -1, -1, -1, -1 };
    u32 tcm_region;
    int tcm_size;

    /*
     * If there are more than one TCM bank of this type,
     * select the TCM bank to operate on in the TCM selection
     * register.
     */
    if (banks > 1)
        asm("mcr    p15, 0, %0, c9, c2, 0"
            : /* No output operands */
            : "r" (bank));

    /* Read the special TCM region register c9, 0 */
    if (!type)
        asm("mrc    p15, 0, %0, c9, c1, 0"
            : "=r" (tcm_region));
    else
        asm("mrc    p15, 0, %0, c9, c1, 1"
            : "=r" (tcm_region));

    tcm_size = tcm_sizes[(tcm_region >> 2) & 0x0f];
    if (tcm_size < 0) {
        pr_err("CPU: %sTCM%d of unknown size\n",
               type ? "I" : "D", bank);
        return -EINVAL;
    } else if (tcm_size > 32) {
        pr_err("CPU: %sTCM%d larger than 32k found\n",
               type ? "I" : "D", bank);
        return -EINVAL;
    } else {
        pr_info("CPU: found %sTCM%d %dk @ %08x, %senabled\n",
            type ? "I" : "D",
            bank,
            tcm_size,
            (tcm_region & 0xfffff000U),
            (tcm_region & 1) ? "" : "not ");
    }

    /* Not much fun you can do with a size 0 bank */
    if (tcm_size == 0)
        return 0;

    /* Force move the TCM bank to where we want it, enable */
    tcm_region = *offset | (tcm_region & 0x00000ffeU) | 1;

    if (!type)
        asm("mcr    p15, 0, %0, c9, c1, 0"
            : /* No output operands */
            : "r" (tcm_region));
    else
        asm("mcr    p15, 0, %0, c9, c1, 1"
            : /* No output operands */
            : "r" (tcm_region));

    /* Increase offset */
    *offset += (tcm_size << 10);

    pr_info("CPU: moved %sTCM%d %dk to %08x, enabled\n",
        type ? "I" : "D",
        bank,
        tcm_size,
        (tcm_region & 0xfffff000U));
    return 0;
}

/*
 * This initializes the TCM memory
 */
void __init tcm_init(void)
{
    u32 tcm_status;
    u8 dtcm_banks;
    u8 itcm_banks;
    size_t dtcm_code_sz = &__edtcm_data - &__sdtcm_data;
    size_t itcm_code_sz = &__eitcm_text - &__sitcm_text;
    char *start;
    char *end;
    char *ram;
    int ret;
    int i;

    /*
     * Prior to ARMv5 there is no TCM, and trying to read the status
     * register will hang the processor.
     */
    if (cpu_architecture() < CPU_ARCH_ARMv5) {
        if (dtcm_code_sz || itcm_code_sz)
            pr_info("CPU TCM: %u bytes of DTCM and %u bytes of "
                "ITCM code compiled in, but no TCM present "
                "in pre-v5 CPU\n", dtcm_code_sz, itcm_code_sz);
        return;
    }

    tcm_status = read_cpuid_tcmstatus();
    dtcm_banks = (tcm_status >> 16) & 0x03;
    itcm_banks = (tcm_status & 0x03);

    /* Values greater than 2 for D/ITCM banks are "reserved" */
    if (dtcm_banks > 2)
        dtcm_banks = 0;
    if (itcm_banks > 2)
        itcm_banks = 0;

    /* Setup DTCM if present */
    if (dtcm_banks > 0) {
        for (i = 0; i < dtcm_banks; i++) {
            ret = setup_tcm_bank(0, i, dtcm_banks, &dtcm_end);
            if (ret)
                return;
        }
        /* This means you compiled more code than fits into DTCM */
        if (dtcm_code_sz > (dtcm_end - DTCM_OFFSET)) {
            pr_info("CPU DTCM: %u bytes of code compiled to "
                "DTCM but only %lu bytes of DTCM present\n",
                dtcm_code_sz, (dtcm_end - DTCM_OFFSET));
            goto no_dtcm;
        }
        dtcm_res.end = dtcm_end - 1;
        request_resource(&iomem_resource, &dtcm_res);
        dtcm_iomap[0].length = dtcm_end - DTCM_OFFSET;
        iotable_init(dtcm_iomap, 1);
        /* Copy data from RAM to DTCM */
        start = &__sdtcm_data;
        end   = &__edtcm_data;
        ram   = &__dtcm_start;
        memcpy(start, ram, dtcm_code_sz);
        pr_debug("CPU DTCM: copied data from %p - %p\n",
             start, end);
        dtcm_present = true;
    } else if (dtcm_code_sz) {
        pr_info("CPU DTCM: %u bytes of code compiled to DTCM but no "
            "DTCM banks present in CPU\n", dtcm_code_sz);
    }

no_dtcm:
    /* Setup ITCM if present */
    if (itcm_banks > 0) {
        for (i = 0; i < itcm_banks; i++) {
            ret = setup_tcm_bank(1, i, itcm_banks, &itcm_end);
            if (ret)
                return;
        }
        /* This means you compiled more code than fits into ITCM */
        if (itcm_code_sz > (itcm_end - ITCM_OFFSET)) {
            pr_info("CPU ITCM: %u bytes of code compiled to "
                "ITCM but only %lu bytes of ITCM present\n",
                itcm_code_sz, (itcm_end - ITCM_OFFSET));
            return;
        }
        itcm_res.end = itcm_end - 1;
        request_resource(&iomem_resource, &itcm_res);
        itcm_iomap[0].length = itcm_end - ITCM_OFFSET;
        iotable_init(itcm_iomap, 1);
        /* Copy code from RAM to ITCM */
        start = &__sitcm_text;
        end   = &__eitcm_text;
        ram   = &__itcm_start;
        memcpy(start, ram, itcm_code_sz);
        pr_debug("CPU ITCM: copied code from %p - %p\n",
             start, end);
        itcm_present = true;
    } else if (itcm_code_sz) {
        pr_info("CPU ITCM: %u bytes of code compiled to ITCM but no "
            "ITCM banks present in CPU\n", itcm_code_sz);
    }
}

/*
 * This creates the TCM memory pool and has to be done later,
 * during the core_initicalls, since the allocator is not yet
 * up and running when the first initialization runs.
 */
static int __init setup_tcm_pool(void)
{
    u32 dtcm_pool_start = (u32) &__edtcm_data;
    u32 itcm_pool_start = (u32) &__eitcm_text;
    int ret;

    /*
     * Set up malloc pool, 2^2 = 4 bytes granularity since
     * the TCM is sometimes just 4 KiB. NB: pages and cache
     * line alignments does not matter in TCM!
     */
    tcm_pool = gen_pool_create(2, -1);

    pr_debug("Setting up TCM memory pool\n");

    /* Add the rest of DTCM to the TCM pool */
    if (dtcm_present) {
        if (dtcm_pool_start < dtcm_end) {
            ret = gen_pool_add(tcm_pool, dtcm_pool_start,
                       dtcm_end - dtcm_pool_start, -1);
            if (ret) {
                pr_err("CPU DTCM: could not add DTCM " \
                       "remainder to pool!\n");
                return ret;
            }
            pr_debug("CPU DTCM: Added %08x bytes @ %08x to " \
                 "the TCM memory pool\n",
                 dtcm_end - dtcm_pool_start,
                 dtcm_pool_start);
        }
    }

    /* Add the rest of ITCM to the TCM pool */
    if (itcm_present) {
        if (itcm_pool_start < itcm_end) {
            ret = gen_pool_add(tcm_pool, itcm_pool_start,
                       itcm_end - itcm_pool_start, -1);
            if (ret) {
                pr_err("CPU ITCM: could not add ITCM " \
                       "remainder to pool!\n");
                return ret;
            }
            pr_debug("CPU ITCM: Added %08x bytes @ %08x to " \
                 "the TCM memory pool\n",
                 itcm_end - itcm_pool_start,
                 itcm_pool_start);
        }
    }
    return 0;
}

core_initcall(setup_tcm_pool);