linux-stable/include/linux/mtd/qinfo.h
Gustavo A. R. Silva 11399346ac mtd: Replace zero-length array with flexible-array
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://lore.kernel.org/r/20200507190033.GA15215@embeddedor
2020-05-26 13:30:06 +05:30

92 lines
2.5 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_MTD_QINFO_H
#define __LINUX_MTD_QINFO_H
#include <linux/mtd/map.h>
#include <linux/wait.h>
#include <linux/spinlock.h>
#include <linux/delay.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/flashchip.h>
#include <linux/mtd/partitions.h>
/* lpddr_private describes lpddr flash chip in memory map
* @ManufactId - Chip Manufacture ID
* @DevId - Chip Device ID
* @qinfo - pointer to qinfo records describing the chip
* @numchips - number of chips including virual RWW partitions
* @chipshift - Chip/partition size 2^chipshift
* @chips - per-chip data structure
*/
struct lpddr_private {
uint16_t ManufactId;
uint16_t DevId;
struct qinfo_chip *qinfo;
int numchips;
unsigned long chipshift;
struct flchip chips[];
};
/* qinfo_query_info structure contains request information for
* each qinfo record
* @major - major number of qinfo record
* @major - minor number of qinfo record
* @id_str - descriptive string to access the record
* @desc - detailed description for the qinfo record
*/
struct qinfo_query_info {
uint8_t major;
uint8_t minor;
char *id_str;
char *desc;
};
/*
* qinfo_chip structure contains necessary qinfo records data
* @DevSizeShift - Device size 2^n bytes
* @BufSizeShift - Program buffer size 2^n bytes
* @TotalBlocksNum - Total number of blocks
* @UniformBlockSizeShift - Uniform block size 2^UniformBlockSizeShift bytes
* @HWPartsNum - Number of hardware partitions
* @SuspEraseSupp - Suspend erase supported
* @SingleWordProgTime - Single word program 2^SingleWordProgTime u-sec
* @ProgBufferTime - Program buffer write 2^ProgBufferTime u-sec
* @BlockEraseTime - Block erase 2^BlockEraseTime m-sec
*/
struct qinfo_chip {
/* General device info */
uint16_t DevSizeShift;
uint16_t BufSizeShift;
/* Erase block information */
uint16_t TotalBlocksNum;
uint16_t UniformBlockSizeShift;
/* Partition information */
uint16_t HWPartsNum;
/* Optional features */
uint16_t SuspEraseSupp;
/* Operation typical time */
uint16_t SingleWordProgTime;
uint16_t ProgBufferTime;
uint16_t BlockEraseTime;
};
/* defines for fixup usage */
#define LPDDR_MFR_ANY 0xffff
#define LPDDR_ID_ANY 0xffff
#define NUMONYX_MFGR_ID 0x0089
#define R18_DEVICE_ID_1G 0x893c
static inline map_word lpddr_build_cmd(u_long cmd, struct map_info *map)
{
map_word val = { {0} };
val.x[0] = cmd;
return val;
}
#define CMD(x) lpddr_build_cmd(x, map)
#define CMDVAL(cmd) cmd.x[0]
struct mtd_info *lpddr_cmdset(struct map_info *);
#endif