linux/drivers/mtd/spi-nor/swp.c
Tudor Ambarus b6cbd9167d mtd: spi-nor: swp: Improve code around spi_nor_check_lock_status_sr()
- bool return value for spi_nor_check_lock_status_sr(), gets rid of
  the return 1,
- introduce temporary variables for better readability.

Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Reviewed-by: Pratyush Yadav <p.yadav@ti.com>
Reviewed-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20210322075131.45093-3-tudor.ambarus@microchip.com
2021-03-31 22:41:34 +03:00

428 lines
11 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* SPI NOR Software Write Protection logic.
*
* Copyright (C) 2005, Intec Automation Inc.
* Copyright (C) 2014, Freescale Semiconductor, Inc.
*/
#include <linux/mtd/mtd.h>
#include <linux/mtd/spi-nor.h>
#include "core.h"
static u8 spi_nor_get_sr_bp_mask(struct spi_nor *nor)
{
u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6)
return mask | SR_BP3_BIT6;
if (nor->flags & SNOR_F_HAS_4BIT_BP)
return mask | SR_BP3;
return mask;
}
static u8 spi_nor_get_sr_tb_mask(struct spi_nor *nor)
{
if (nor->flags & SNOR_F_HAS_SR_TB_BIT6)
return SR_TB_BIT6;
else
return SR_TB_BIT5;
}
static u64 spi_nor_get_min_prot_length_sr(struct spi_nor *nor)
{
unsigned int bp_slots, bp_slots_needed;
u8 mask = spi_nor_get_sr_bp_mask(nor);
/* Reserved one for "protect none" and one for "protect all". */
bp_slots = (1 << hweight8(mask)) - 2;
bp_slots_needed = ilog2(nor->info->n_sectors);
if (bp_slots_needed > bp_slots)
return nor->info->sector_size <<
(bp_slots_needed - bp_slots);
else
return nor->info->sector_size;
}
static void spi_nor_get_locked_range_sr(struct spi_nor *nor, u8 sr, loff_t *ofs,
uint64_t *len)
{
struct mtd_info *mtd = &nor->mtd;
u64 min_prot_len;
u8 mask = spi_nor_get_sr_bp_mask(nor);
u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
u8 bp, val = sr & mask;
if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3_BIT6)
val = (val & ~SR_BP3_BIT6) | SR_BP3;
bp = val >> SR_BP_SHIFT;
if (!bp) {
/* No protection */
*ofs = 0;
*len = 0;
return;
}
min_prot_len = spi_nor_get_min_prot_length_sr(nor);
*len = min_prot_len << (bp - 1);
if (*len > mtd->size)
*len = mtd->size;
if (nor->flags & SNOR_F_HAS_SR_TB && sr & tb_mask)
*ofs = 0;
else
*ofs = mtd->size - *len;
}
/*
* Return true if the entire region is locked (if @locked is true) or unlocked
* (if @locked is false); false otherwise.
*/
static bool spi_nor_check_lock_status_sr(struct spi_nor *nor, loff_t ofs,
uint64_t len, u8 sr, bool locked)
{
loff_t lock_offs, lock_offs_max, offs_max;
uint64_t lock_len;
if (!len)
return true;
spi_nor_get_locked_range_sr(nor, sr, &lock_offs, &lock_len);
lock_offs_max = lock_offs + lock_len;
offs_max = ofs + len;
if (locked)
/* Requested range is a sub-range of locked range */
return (offs_max <= lock_offs_max) && (ofs >= lock_offs);
else
/* Requested range does not overlap with locked range */
return (ofs >= lock_offs_max) || (offs_max <= lock_offs);
}
static bool spi_nor_is_locked_sr(struct spi_nor *nor, loff_t ofs, uint64_t len,
u8 sr)
{
return spi_nor_check_lock_status_sr(nor, ofs, len, sr, true);
}
static bool spi_nor_is_unlocked_sr(struct spi_nor *nor, loff_t ofs,
uint64_t len, u8 sr)
{
return spi_nor_check_lock_status_sr(nor, ofs, len, sr, false);
}
/*
* Lock a region of the flash. Compatible with ST Micro and similar flash.
* Supports the block protection bits BP{0,1,2}/BP{0,1,2,3} in the status
* register
* (SR). Does not support these features found in newer SR bitfields:
* - SEC: sector/block protect - only handle SEC=0 (block protect)
* - CMP: complement protect - only support CMP=0 (range is not complemented)
*
* Support for the following is provided conditionally for some flash:
* - TB: top/bottom protect
*
* Sample table portion for 8MB flash (Winbond w25q64fw):
*
* SEC | TB | BP2 | BP1 | BP0 | Prot Length | Protected Portion
* --------------------------------------------------------------------------
* X | X | 0 | 0 | 0 | NONE | NONE
* 0 | 0 | 0 | 0 | 1 | 128 KB | Upper 1/64
* 0 | 0 | 0 | 1 | 0 | 256 KB | Upper 1/32
* 0 | 0 | 0 | 1 | 1 | 512 KB | Upper 1/16
* 0 | 0 | 1 | 0 | 0 | 1 MB | Upper 1/8
* 0 | 0 | 1 | 0 | 1 | 2 MB | Upper 1/4
* 0 | 0 | 1 | 1 | 0 | 4 MB | Upper 1/2
* X | X | 1 | 1 | 1 | 8 MB | ALL
* ------|-------|-------|-------|-------|---------------|-------------------
* 0 | 1 | 0 | 0 | 1 | 128 KB | Lower 1/64
* 0 | 1 | 0 | 1 | 0 | 256 KB | Lower 1/32
* 0 | 1 | 0 | 1 | 1 | 512 KB | Lower 1/16
* 0 | 1 | 1 | 0 | 0 | 1 MB | Lower 1/8
* 0 | 1 | 1 | 0 | 1 | 2 MB | Lower 1/4
* 0 | 1 | 1 | 1 | 0 | 4 MB | Lower 1/2
*
* Returns negative on errors, 0 on success.
*/
static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
{
struct mtd_info *mtd = &nor->mtd;
u64 min_prot_len;
int ret, status_old, status_new;
u8 mask = spi_nor_get_sr_bp_mask(nor);
u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
u8 pow, val;
loff_t lock_len;
bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB;
bool use_top;
ret = spi_nor_read_sr(nor, nor->bouncebuf);
if (ret)
return ret;
status_old = nor->bouncebuf[0];
/* If nothing in our range is unlocked, we don't need to do anything */
if (spi_nor_is_locked_sr(nor, ofs, len, status_old))
return 0;
/* If anything below us is unlocked, we can't use 'bottom' protection */
if (!spi_nor_is_locked_sr(nor, 0, ofs, status_old))
can_be_bottom = false;
/* If anything above us is unlocked, we can't use 'top' protection */
if (!spi_nor_is_locked_sr(nor, ofs + len, mtd->size - (ofs + len),
status_old))
can_be_top = false;
if (!can_be_bottom && !can_be_top)
return -EINVAL;
/* Prefer top, if both are valid */
use_top = can_be_top;
/* lock_len: length of region that should end up locked */
if (use_top)
lock_len = mtd->size - ofs;
else
lock_len = ofs + len;
if (lock_len == mtd->size) {
val = mask;
} else {
min_prot_len = spi_nor_get_min_prot_length_sr(nor);
pow = ilog2(lock_len) - ilog2(min_prot_len) + 1;
val = pow << SR_BP_SHIFT;
if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3)
val = (val & ~SR_BP3) | SR_BP3_BIT6;
if (val & ~mask)
return -EINVAL;
/* Don't "lock" with no region! */
if (!(val & mask))
return -EINVAL;
}
status_new = (status_old & ~mask & ~tb_mask) | val;
/* Disallow further writes if WP pin is asserted */
status_new |= SR_SRWD;
if (!use_top)
status_new |= tb_mask;
/* Don't bother if they're the same */
if (status_new == status_old)
return 0;
/* Only modify protection if it will not unlock other areas */
if ((status_new & mask) < (status_old & mask))
return -EINVAL;
return spi_nor_write_sr_and_check(nor, status_new);
}
/*
* Unlock a region of the flash. See spi_nor_sr_lock() for more info
*
* Returns negative on errors, 0 on success.
*/
static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
{
struct mtd_info *mtd = &nor->mtd;
u64 min_prot_len;
int ret, status_old, status_new;
u8 mask = spi_nor_get_sr_bp_mask(nor);
u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
u8 pow, val;
loff_t lock_len;
bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB;
bool use_top;
ret = spi_nor_read_sr(nor, nor->bouncebuf);
if (ret)
return ret;
status_old = nor->bouncebuf[0];
/* If nothing in our range is locked, we don't need to do anything */
if (spi_nor_is_unlocked_sr(nor, ofs, len, status_old))
return 0;
/* If anything below us is locked, we can't use 'top' protection */
if (!spi_nor_is_unlocked_sr(nor, 0, ofs, status_old))
can_be_top = false;
/* If anything above us is locked, we can't use 'bottom' protection */
if (!spi_nor_is_unlocked_sr(nor, ofs + len, mtd->size - (ofs + len),
status_old))
can_be_bottom = false;
if (!can_be_bottom && !can_be_top)
return -EINVAL;
/* Prefer top, if both are valid */
use_top = can_be_top;
/* lock_len: length of region that should remain locked */
if (use_top)
lock_len = mtd->size - (ofs + len);
else
lock_len = ofs;
if (lock_len == 0) {
val = 0; /* fully unlocked */
} else {
min_prot_len = spi_nor_get_min_prot_length_sr(nor);
pow = ilog2(lock_len) - ilog2(min_prot_len) + 1;
val = pow << SR_BP_SHIFT;
if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3)
val = (val & ~SR_BP3) | SR_BP3_BIT6;
/* Some power-of-two sizes are not supported */
if (val & ~mask)
return -EINVAL;
}
status_new = (status_old & ~mask & ~tb_mask) | val;
/* Don't protect status register if we're fully unlocked */
if (lock_len == 0)
status_new &= ~SR_SRWD;
if (!use_top)
status_new |= tb_mask;
/* Don't bother if they're the same */
if (status_new == status_old)
return 0;
/* Only modify protection if it will not lock other areas */
if ((status_new & mask) > (status_old & mask))
return -EINVAL;
return spi_nor_write_sr_and_check(nor, status_new);
}
/*
* Check if a region of the flash is (completely) locked. See spi_nor_sr_lock()
* for more info.
*
* Returns 1 if entire region is locked, 0 if any portion is unlocked, and
* negative on errors.
*/
static int spi_nor_sr_is_locked(struct spi_nor *nor, loff_t ofs, uint64_t len)
{
int ret;
ret = spi_nor_read_sr(nor, nor->bouncebuf);
if (ret)
return ret;
return spi_nor_is_locked_sr(nor, ofs, len, nor->bouncebuf[0]);
}
static const struct spi_nor_locking_ops spi_nor_sr_locking_ops = {
.lock = spi_nor_sr_lock,
.unlock = spi_nor_sr_unlock,
.is_locked = spi_nor_sr_is_locked,
};
void spi_nor_init_default_locking_ops(struct spi_nor *nor)
{
nor->params->locking_ops = &spi_nor_sr_locking_ops;
}
static int spi_nor_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
{
struct spi_nor *nor = mtd_to_spi_nor(mtd);
int ret;
ret = spi_nor_lock_and_prep(nor);
if (ret)
return ret;
ret = nor->params->locking_ops->lock(nor, ofs, len);
spi_nor_unlock_and_unprep(nor);
return ret;
}
static int spi_nor_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
{
struct spi_nor *nor = mtd_to_spi_nor(mtd);
int ret;
ret = spi_nor_lock_and_prep(nor);
if (ret)
return ret;
ret = nor->params->locking_ops->unlock(nor, ofs, len);
spi_nor_unlock_and_unprep(nor);
return ret;
}
static int spi_nor_is_locked(struct mtd_info *mtd, loff_t ofs, uint64_t len)
{
struct spi_nor *nor = mtd_to_spi_nor(mtd);
int ret;
ret = spi_nor_lock_and_prep(nor);
if (ret)
return ret;
ret = nor->params->locking_ops->is_locked(nor, ofs, len);
spi_nor_unlock_and_unprep(nor);
return ret;
}
/**
* spi_nor_try_unlock_all() - Tries to unlock the entire flash memory array.
* @nor: pointer to a 'struct spi_nor'.
*
* Some SPI NOR flashes are write protected by default after a power-on reset
* cycle, in order to avoid inadvertent writes during power-up. Backward
* compatibility imposes to unlock the entire flash memory array at power-up
* by default.
*
* Unprotecting the entire flash array will fail for boards which are hardware
* write-protected. Thus any errors are ignored.
*/
void spi_nor_try_unlock_all(struct spi_nor *nor)
{
int ret;
if (!(nor->flags & SNOR_F_HAS_LOCK))
return;
dev_dbg(nor->dev, "Unprotecting entire flash array\n");
ret = spi_nor_unlock(&nor->mtd, 0, nor->params->size);
if (ret)
dev_dbg(nor->dev, "Failed to unlock the entire flash memory array\n");
}
void spi_nor_register_locking_ops(struct spi_nor *nor)
{
struct mtd_info *mtd = &nor->mtd;
if (!nor->params->locking_ops)
return;
mtd->_lock = spi_nor_lock;
mtd->_unlock = spi_nor_unlock;
mtd->_is_locked = spi_nor_is_locked;
}