--- /dev/null
+ARM TCM (Tightly-Coupled Memory) handling in Linux
+----
+Written by Linus Walleij <linus.walleij@stericsson.com>
+
+Some ARM SoC:s have a so-called TCM (Tightly-Coupled Memory).
+This is usually just a few (4-64) KiB of RAM inside the ARM
+processor.
+
+Due to being embedded inside the CPU The TCM has a
+Harvard-architecture, so there is an ITCM (instruction TCM)
+and a DTCM (data TCM). The DTCM can not contain any
+instructions, but the ITCM can actually contain data.
+The size of DTCM or ITCM is minimum 4KiB so the typical
+minimum configuration is 4KiB ITCM and 4KiB DTCM.
+
+ARM CPU:s have special registers to read out status, physical
+location and size of TCM memories. arch/arm/include/asm/cputype.h
+defines a CPUID_TCM register that you can read out from the
+system control coprocessor. Documentation from ARM can be found
+at http://infocenter.arm.com, search for "TCM Status Register"
+to see documents for all CPUs. Reading this register you can
+determine if ITCM (bit 0) and/or DTCM (bit 16) is present in the
+machine.
+
+There is further a TCM region register (search for "TCM Region
+Registers" at the ARM site) that can report and modify the location
+size of TCM memories at runtime. This is used to read out and modify
+TCM location and size. Notice that this is not a MMU table: you
+actually move the physical location of the TCM around. At the
+place you put it, it will mask any underlying RAM from the
+CPU so it is usually wise not to overlap any physical RAM with
+the TCM. The TCM memory exists totally outside the MMU and will
+override any MMU mappings.
+
+Code executing inside the ITCM does not "see" any MMU mappings
+and e.g. register accesses must be made to physical addresses.
+
+TCM is used for a few things:
+
+- FIQ and other interrupt handlers that need deterministic
+ timing and cannot wait for cache misses.
+
+- Idle loops where all external RAM is set to self-refresh
+ retention mode, so only on-chip RAM is accessible by
+ the CPU and then we hang inside ITCM waiting for an
+ interrupt.
+
+- Other operations which implies shutting off or reconfiguring
+ the external RAM controller.
+
+There is an interface for using TCM on the ARM architecture
+in <asm/tcm.h>. Using this interface it is possible to:
+
+- Define the physical address and size of ITCM and DTCM.
+
+- Tag functions to be compiled into ITCM.
+
+- Tag data and constants to be allocated to DTCM and ITCM.
+
+- Have the remaining TCM RAM added to a special
+ allocation pool with gen_pool_create() and gen_pool_add()
+ and provice tcm_alloc() and tcm_free() for this
+ memory. Such a heap is great for things like saving
+ device state when shutting off device power domains.
+
+A machine that has TCM memory shall select HAVE_TCM in
+arch/arm/Kconfig for itself, and then the
+rest of the functionality will depend on the physical
+location and size of ITCM and DTCM to be defined in
+mach/memory.h for the machine. Code that needs to use
+TCM shall #include <asm/tcm.h> If the TCM is not located
+at the place given in memory.h it will be moved using
+the TCM Region registers.
+
+Functions to go into itcm can be tagged like this:
+int __tcmfunc foo(int bar);
+
+Variables to go into dtcm can be tagged like this:
+int __tcmdata foo;
+
+Constants can be tagged like this:
+int __tcmconst foo;
+
+To put assembler into TCM just use
+.section ".tcm.text" or .section ".tcm.data"
+respectively.
+
+Example code:
+
+#include <asm/tcm.h>
+
+/* Uninitialized data */
+static u32 __tcmdata tcmvar;
+/* Initialized data */
+static u32 __tcmdata tcmassigned = 0x2BADBABEU;
+/* Constant */
+static const u32 __tcmconst tcmconst = 0xCAFEBABEU;
+
+static void __tcmlocalfunc tcm_to_tcm(void)
+{
+ int i;
+ for (i = 0; i < 100; i++)
+ tcmvar ++;
+}
+
+static void __tcmfunc hello_tcm(void)
+{
+ /* Some abstract code that runs in ITCM */
+ int i;
+ for (i = 0; i < 100; i++) {
+ tcmvar ++;
+ }
+ tcm_to_tcm();
+}
+
+static void __init test_tcm(void)
+{
+ u32 *tcmem;
+ int i;
+
+ hello_tcm();
+ printk("Hello TCM executed from ITCM RAM\n");
+
+ printk("TCM variable from testrun: %u @ %p\n", tcmvar, &tcmvar);
+ tcmvar = 0xDEADBEEFU;
+ printk("TCM variable: 0x%x @ %p\n", tcmvar, &tcmvar);
+
+ printk("TCM assigned variable: 0x%x @ %p\n", tcmassigned, &tcmassigned);
+
+ printk("TCM constant: 0x%x @ %p\n", tcmconst, &tcmconst);
+
+ /* Allocate some TCM memory from the pool */
+ tcmem = tcm_alloc(20);
+ if (tcmem) {
+ printk("TCM Allocated 20 bytes of TCM @ %p\n", tcmem);
+ tcmem[0] = 0xDEADBEEFU;
+ tcmem[1] = 0x2BADBABEU;
+ tcmem[2] = 0xCAFEBABEU;
+ tcmem[3] = 0xDEADBEEFU;
+ tcmem[4] = 0x2BADBABEU;
+ for (i = 0; i < 5; i++)
+ printk("TCM tcmem[%d] = %08x\n", i, tcmem[i]);
+ tcm_free(tcmem, 20);
+ }
+}
depends on GENERIC_CLOCKEVENTS
default y if SMP && !LOCAL_TIMERS
+config HAVE_TCM
+ bool
+ select GENERIC_ALLOCATOR
+
config NO_IOPORT
bool
bool "ST-Ericsson U300 Series"
depends on MMU
select CPU_ARM926T
+ select HAVE_TCM
select ARM_AMBA
select ARM_VIC
select GENERIC_TIME
return read_cpuid(CPUID_CACHETYPE);
}
+static inline unsigned int __attribute_const__ read_cpuid_tcmstatus(void)
+{
+ return read_cpuid(CPUID_TCM);
+}
+
/*
* Intel's XScale3 core supports some v6 features (supersections, L2)
* but advertises itself as v5 as it does not support the v6 ISA. For
--- /dev/null
+/*
+ *
+ * Copyright (C) 2008-2009 ST-Ericsson AB
+ * License terms: GNU General Public License (GPL) version 2
+ *
+ * Author: Rickard Andersson <rickard.andersson@stericsson.com>
+ * Author: Linus Walleij <linus.walleij@stericsson.com>
+ *
+ */
+#ifndef __ASMARM_TCM_H
+#define __ASMARM_TCM_H
+
+#ifndef CONFIG_HAVE_TCM
+#error "You should not be including tcm.h unless you have a TCM!"
+#endif
+
+#include <linux/compiler.h>
+
+/* Tag variables with this */
+#define __tcmdata __section(.tcm.data)
+/* Tag constants with this */
+#define __tcmconst __section(.tcm.rodata)
+/* Tag functions inside TCM called from outside TCM with this */
+#define __tcmfunc __attribute__((long_call)) __section(.tcm.text) noinline
+/* Tag function inside TCM called from inside TCM with this */
+#define __tcmlocalfunc __section(.tcm.text)
+
+void *tcm_alloc(size_t len);
+void tcm_free(void *addr, size_t len);
+
+#endif
obj-$(CONFIG_ARM_THUMBEE) += thumbee.o
obj-$(CONFIG_KGDB) += kgdb.o
obj-$(CONFIG_ARM_UNWIND) += unwind.o
+obj-$(CONFIG_HAVE_TCM) += tcm.o
obj-$(CONFIG_CRUNCH) += crunch.o crunch-bits.o
AFLAGS_crunch-bits.o := -Wa,-mcpu=ep9312
#include "compat.h"
#include "atags.h"
+#include "tcm.h"
#ifndef MEM_SIZE
#define MEM_SIZE (16*1024*1024)
#endif
cpu_init();
+ tcm_init();
/*
* Set up various architecture-specific pointers
--- /dev/null
+/*
+ * 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/page.h> /* PAGE_SHIFT */
+#include <asm/cputype.h>
+#include <asm/mach/map.h>
+#include <mach/memory.h>
+#include "tcm.h"
+
+/* Scream and warn about misuse */
+#if !defined(ITCM_OFFSET) || !defined(ITCM_END) || \
+ !defined(DTCM_OFFSET) || !defined(DTCM_END)
+#error "TCM support selected but offsets not defined!"
+#endif
+
+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;
+
+/*
+ * TCM memory resources
+ */
+static struct resource dtcm_res = {
+ .name = "DTCM RAM",
+ .start = DTCM_OFFSET,
+ .end = DTCM_END,
+ .flags = IORESOURCE_MEM
+};
+
+static struct resource itcm_res = {
+ .name = "ITCM RAM",
+ .start = ITCM_OFFSET,
+ .end = ITCM_END,
+ .flags = IORESOURCE_MEM
+};
+
+static struct map_desc dtcm_iomap[] __initdata = {
+ {
+ .virtual = DTCM_OFFSET,
+ .pfn = __phys_to_pfn(DTCM_OFFSET),
+ .length = (DTCM_END - DTCM_OFFSET + 1),
+ .type = MT_UNCACHED
+ }
+};
+
+static struct map_desc itcm_iomap[] __initdata = {
+ {
+ .virtual = ITCM_OFFSET,
+ .pfn = __phys_to_pfn(ITCM_OFFSET),
+ .length = (ITCM_END - ITCM_OFFSET + 1),
+ .type = MT_UNCACHED
+ }
+};
+
+/*
+ * 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 void __init setup_tcm_bank(u8 type, u32 offset, u32 expected_size)
+{
+ 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;
+
+ /* 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 of unknown size!\n",
+ type ? "I" : "D");
+ } else {
+ pr_info("CPU: found %sTCM %dk @ %08x, %senabled\n",
+ type ? "I" : "D",
+ tcm_size,
+ (tcm_region & 0xfffff000U),
+ (tcm_region & 1) ? "" : "not ");
+ }
+
+ if (tcm_size != expected_size) {
+ pr_crit("CPU: %sTCM was detected %dk but expected %dk!\n",
+ type ? "I" : "D",
+ tcm_size,
+ expected_size);
+ /* Adjust to the expected size? what can we do... */
+ }
+
+ /* 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));
+
+ pr_debug("CPU: moved %sTCM %dk to %08x, enabled\n",
+ type ? "I" : "D",
+ tcm_size,
+ (tcm_region & 0xfffff000U));
+}
+
+/*
+ * This initializes the TCM memory
+ */
+void __init tcm_init(void)
+{
+ u32 tcm_status = read_cpuid_tcmstatus();
+ char *start;
+ char *end;
+ char *ram;
+
+ /* Setup DTCM if present */
+ if (tcm_status & (1 << 16)) {
+ setup_tcm_bank(0, DTCM_OFFSET,
+ (DTCM_END - DTCM_OFFSET + 1) >> 10);
+ request_resource(&iomem_resource, &dtcm_res);
+ iotable_init(dtcm_iomap, 1);
+ /* Copy data from RAM to DTCM */
+ start = &__sdtcm_data;
+ end = &__edtcm_data;
+ ram = &__dtcm_start;
+ memcpy(start, ram, (end-start));
+ pr_debug("CPU DTCM: copied data from %p - %p\n", start, end);
+ }
+
+ /* Setup ITCM if present */
+ if (tcm_status & 1) {
+ setup_tcm_bank(1, ITCM_OFFSET,
+ (ITCM_END - ITCM_OFFSET + 1) >> 10);
+ request_resource(&iomem_resource, &itcm_res);
+ iotable_init(itcm_iomap, 1);
+ /* Copy code from RAM to ITCM */
+ start = &__sitcm_text;
+ end = &__eitcm_text;
+ ram = &__itcm_start;
+ 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 & (1 << 16)) {
+ if (dtcm_pool_start < DTCM_END) {
+ ret = gen_pool_add(tcm_pool, dtcm_pool_start,
+ DTCM_END - dtcm_pool_start + 1, -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 + 1,
+ dtcm_pool_start);
+ }
+ }
+
+ /* Add the rest of ITCM to the TCM pool */
+ if (tcm_status & 1) {
+ if (itcm_pool_start < ITCM_END) {
+ ret = gen_pool_add(tcm_pool, itcm_pool_start,
+ ITCM_END - itcm_pool_start + 1, -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 + 1,
+ itcm_pool_start);
+ }
+ }
+ return 0;
+}
+
+core_initcall(setup_tcm_pool);
--- /dev/null
+/*
+ * 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>
+ */
+
+#ifdef CONFIG_HAVE_TCM
+void __init tcm_init(void);
+#else
+/* No TCM support, just blank inlines to be optimized out */
+inline void tcm_init(void)
+{
+}
+#endif
}
_edata_loc = __data_loc + SIZEOF(.data);
+#ifdef CONFIG_HAVE_TCM
+ /*
+ * We align everything to a page boundary so we can
+ * free it after init has commenced and TCM contents have
+ * been copied to its destination.
+ */
+ .tcm_start : {
+ . = ALIGN(PAGE_SIZE);
+ __tcm_start = .;
+ __itcm_start = .;
+ }
+
+ /*
+ * Link these to the ITCM RAM
+ * Put VMA to the TCM address and LMA to the common RAM
+ * and we'll upload the contents from RAM to TCM and free
+ * the used RAM after that.
+ */
+ .text_itcm ITCM_OFFSET : AT(__itcm_start)
+ {
+ __sitcm_text = .;
+ *(.tcm.text)
+ *(.tcm.rodata)
+ . = ALIGN(4);
+ __eitcm_text = .;
+ }
+
+ /*
+ * Reset the dot pointer, this is needed to create the
+ * relative __dtcm_start below (to be used as extern in code).
+ */
+ . = ADDR(.tcm_start) + SIZEOF(.tcm_start) + SIZEOF(.text_itcm);
+
+ .dtcm_start : {
+ __dtcm_start = .;
+ }
+
+ /* TODO: add remainder of ITCM as well, that can be used for data! */
+ .data_dtcm DTCM_OFFSET : AT(__dtcm_start)
+ {
+ . = ALIGN(4);
+ __sdtcm_data = .;
+ *(.tcm.data)
+ . = ALIGN(4);
+ __edtcm_data = .;
+ }
+
+ /* Reset the dot pointer or the linker gets confused */
+ . = ADDR(.dtcm_start) + SIZEOF(.data_dtcm);
+
+ /* End marker for freeing TCM copy in linked object */
+ .tcm_end : AT(ADDR(.dtcm_start) + SIZEOF(.data_dtcm)){
+ . = ALIGN(PAGE_SIZE);
+ __tcm_end = .;
+ }
+#endif
+
.bss : {
__bss_start = .; /* BSS */
*(.bss)
#endif
/*
+ * TCM memory whereabouts
+ */
+#define ITCM_OFFSET 0xffff2000
+#define ITCM_END 0xffff3fff
+#define DTCM_OFFSET 0xffff4000
+#define DTCM_END 0xffff5fff
+
+/*
* We enable a real big DMA buffer if need be.
*/
#define CONSISTENT_DMA_SIZE SZ_4M
void free_initmem(void)
{
+#ifdef CONFIG_HAVE_TCM
+ extern char *__tcm_start, *__tcm_end;
+
+ totalram_pages += free_area(__phys_to_pfn(__pa(__tcm_start)),
+ __phys_to_pfn(__pa(__tcm_end)),
+ "TCM link");
+#endif
+
if (!machine_is_integrator() && !machine_is_cintegrator())
totalram_pages += free_area(__phys_to_pfn(__pa(__init_begin)),
__phys_to_pfn(__pa(__init_end)),
git://ftp.safe.ca / safe / jmp / linux-2.6 / commitdiff