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Diffstat (limited to 'arch/blackfin/mm/isram-driver.c')
| -rw-r--r-- | arch/blackfin/mm/isram-driver.c | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/arch/blackfin/mm/isram-driver.c b/arch/blackfin/mm/isram-driver.c new file mode 100644 index 000000000000..22913e7a1818 --- /dev/null +++ b/arch/blackfin/mm/isram-driver.c @@ -0,0 +1,201 @@ +/* + * 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); + |