/*
* Description: Instruction SRAM accessor functions for the Blackfin
*
* Copyright 2008 Analog Devices Inc.
*
* Bugs: Enter bugs at http://blackfin.uclinux.org/
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see the file COPYING, or write
* to the Free Software Foundation, Inc.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/sched.h>
#include <asm/blackfin.h>
/*
* IMPORTANT WARNING ABOUT THESE FUNCTIONS
*
* The emulator will not function correctly if a write command is left in
* ITEST_COMMAND or DTEST_COMMAND AND access to cache memory is needed by
* the emulator. To avoid such problems, ensure that both ITEST_COMMAND
* and DTEST_COMMAND are zero when exiting these functions.
*/
/*
* On the Blackfin, L1 instruction sram (which operates at core speeds) can not
* be accessed by a normal core load, so we need to go through a few hoops to
* read/write it.
* To try to make it easier - we export a memcpy interface, where either src or
* dest can be in this special L1 memory area.
* The low level read/write functions should not be exposed to the rest of the
* kernel, since they operate on 64-bit data, and need specific address alignment
*/
static DEFINE_SPINLOCK(dtest_lock);
/* Takes a void pointer */
#define IADDR2DTEST(x) \
({ unsigned long __addr = (unsigned long)(x); \
(__addr & 0x47F8) | /* address bits 14 & 10:3 */ \
(__addr & 0x0800) << 15 | /* address bit 11 */ \
(__addr & 0x3000) << 4 | /* address bits 13:12 */ \
(__addr & 0x8000) << 8 | /* address bit 15 */ \
(0x1000004); /* isram access */ \
})
/* Takes a pointer, and returns the offset (in bits) which things should be shifted */
#define ADDR2OFFSET(x) ((((unsigned long)(x)) & 0x7) * 8)
/* Takes a pointer, determines if it is the last byte in the isram 64-bit data type */
#define ADDR2LAST(x) ((((unsigned long)x) & 0x7) == 0x7)
static void isram_write(const void *addr, uint64_t data)
{
uint32_t cmd;
unsigned long flags;
if (addr >= (void *)(L1_CODE_START + L1_CODE_LENGTH))
return;
cmd = IADDR2DTEST(addr) | 1; /* write */
/*
* Writes to DTEST_DATA[0:1] need to be atomic with write to DTEST_COMMAND
* While in exception context - atomicity is guaranteed or double fault
*/
spin_lock_irqsave(&dtest_lock, flags);
bfin_write_DTEST_DATA0(data & 0xFFFFFFFF);
bfin_write_DTEST_DATA1(data >> 32);
/* use the builtin, since interrupts are already turned off */
__builtin_bfin_csync();
bfin_write_DTEST_COMMAND(cmd);
__builtin_bfin_csync();
bfin_write_DTEST_COMMAND(0);
__builtin_bfin_csync();
spin_unlock_irqrestore(&dtest_lock, flags);
}
static uint64_t isram_read(const void *addr)
{
uint32_t cmd;
unsigned long flags;
uint64_t ret;
if (addr > (void *)(L1_CODE_START + L1_CODE_LENGTH))
return 0;
cmd = IADDR2DTEST(addr) | 0; /* read */
/*
* Reads of DTEST_DATA[0:1] need to be atomic with write to DTEST_COMMAND
* While in exception context - atomicity is guaranteed or double fault
*/
spin_lock_irqsave(&dtest_lock, flags);
/* use the builtin, since interrupts are already turned off */
__builtin_bfin_csync();
bfin_write_DTEST_COMMAND(cmd);
__builtin_bfin_csync();
ret = bfin_read_DTEST_DATA0() | ((uint64_t)bfin_read_DTEST_DATA1() << 32);
bfin_write_DTEST_COMMAND(0);
__builtin_bfin_csync();
spin_unlock_irqrestore(&dtest_lock, flags);
return ret;
}
static bool isram_check_addr(const void *addr, size_t n)
{
if ((addr >= (void *)L1_CODE_START) &&
(addr < (void *)(L1_CODE_START + L1_CODE_LENGTH))) {
if ((addr + n) > (void *)(L1_CODE_START + L1_CODE_LENGTH)) {
show_stack(NULL, NULL);
printk(KERN_ERR "isram_memcpy: copy involving %p length "
"(%zu) too long\n", addr, n);
}
return true;
}
return false;
}
/*
* The isram_memcpy() function copies n bytes from memory area src to memory area dest.
* The isram_memcpy() function returns a pointer to dest.
* Either dest or src can be in L1 instruction sram.
*/
void *isram_memcpy(void *dest, const void *src, size_t n)
{
uint64_t data_in = 0, data_out = 0;
size_t count;
bool dest_in_l1, src_in_l1, need_data, put_data;
unsigned char byte, *src_byte, *dest_byte;
src_byte = (unsigned char *)src;
dest_byte = (unsigned char *)dest;
dest_in_l1 = isram_check_addr(dest, n);
src_in_l1 = isram_check_addr(src, n);
need_data = true;
put_data = true;
for (count = 0; count < n; count++) {
if (src_in_l1) {
if (need_data) {
data_in = isram_read(src + count);
need_data = false;
}
if (ADDR2LAST(src + count))
need_data = true;
byte = (unsigned char)((data_in >> ADDR2OFFSET(src + count)) & 0xff);
} else {
/* src is in L2 or L3 - so just dereference*/
byte = src_byte[count];
}
if (dest_in_l1) {
if (put_data) {
data_out = isram_read(dest + count);
put_data = false;
}
data_out &= ~((uint64_t)0xff << ADDR2OFFSET(dest + count));
data_out |= ((uint64_t)byte << ADDR2OFFSET(dest + count));
if (ADDR2LAST(dest + count)) {
put_data = true;
isram_write(dest + count, data_out);
}
} else {
/* dest in L2 or L3 - so just dereference */
dest_byte[count] = byte;
}
}
/* make sure we dump the last byte if necessary */
if (dest_in_l1 && !put_data)
isram_write(dest + count, data_out);
return dest;
}
EXPORT_SYMBOL(isram_memcpy);
