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tcm.c

/*
 * 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 <linus.walleij@stericsson.com>
 * Author: Rickard Andersson <rickard.andersson@stericsson.com>
 */
#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 <mach/memory.h>
#include "tcm.h"

static struct gen_pool *tcm_pool;

/* 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);

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 ");
      }

      /* 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 = read_cpuid_tcmstatus();
      u8 dtcm_banks = (tcm_status >> 16) & 0x03;
      u8 itcm_banks = (tcm_status & 0x03);
      char *start;
      char *end;
      char *ram;
      int ret;
      int i;

      /* 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;
            }
            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;
            /* This means you compiled more code than fits into DTCM */
            BUG_ON((end - start) > (dtcm_end - DTCM_OFFSET));
            memcpy(start, ram, (end-start));
            pr_debug("CPU DTCM: copied data from %p - %p\n", start, end);
      }

      /* 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;
            }
            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;
            /* This means you compiled more code than fits into ITCM */
            BUG_ON((end - start) > (itcm_end - ITCM_OFFSET));
            memcpy(start, ram, (end-start));
            pr_debug("CPU ITCM: copied code from %p - %p\n", start, end);
      }
}

/*
 * 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 tcm_status = read_cpuid_tcmstatus();
      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 (tcm_status & (0x03 << 16)) {
            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 (tcm_status & 0x03) {
            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);

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