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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]
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 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200226222722.GA18020@embeddedor
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Currently, this driver sticks to the legacy NAND model because it was
upstreamed before commit 2d472aba15ff ("mtd: nand: document the NAND
controller/NAND chip DT representation"). However, relying on the
dummy_controller is already deprecated.
Switch over to the new controller/chip representation.
The struct denali_nand_info has been split into denali_controller
and denali_chip, to contain the controller data, per-chip data,
respectively.
One problem is, this commit changes the DT binding. So, as always,
the backward compatibility must be taken into consideration.
In the new binding, the controller node expects
#address-cells = <1>;
#size-cells = <0>;
... since the child nodes represent NAND chips.
In the old binding, the controller node may have subnodes, but they
are MTD partitions.
The denali_dt_is_legacy_binding() exploits it to distinguish old/new
platforms.
Going forward, the old binding is only allowed for existing DT files.
I updated the binding document.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
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Use 'bool' type for the following boolean parameters.
- write (write or read?)
- dma_avail (DMA engine available or not?)
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
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The Denali IP adopts the syndrome page layout (payload and ECC are
interleaved). The *_page_raw() and *_oob() callbacks are complicated
because they must hide the underlying layout used by the hardware,
and always return contiguous in-band and out-of-band data.
The Denali IP cannot reuse nand_{read,write}_page_raw_syndrome()
in nand_base.c because its hardware ECC engine skips some of first
bytes in OOB. That is why this driver implements specially-crafted
*_page_raw() and *_oob() hooks.
Currently, similar code is duplicated to reorganize the data layout.
For example, denali_read_page_raw() and denali_write_page_raw() look
almost the same. The complexity is partly due to the DMA transfer
used for better performance of *_page_raw() accessors.
On second thought, we do not need to care about their performance
because MTD_OPS_RAW is rarely used.
Let's focus on code cleanups rather than the performance. This commit
removes the internal buffer for DMA, and factors out as much code as
possible.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
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This is a leftover of commit 997cde2a2220 ("mtd: nand: denali: skip
driver internal bounce buffer when possible").
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
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The reason of including <linux/bitops.h> here is just for BIT() and
GENMASK macros.
Since commit 8bd9cb51daac8 ("locking/atomics, asm-generic: Move some
macros from <linux/bitops.h> to a new <linux/bits.h> file"),
<linux/bits.h> is enough for such compile-time macros.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
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Use SPDX-License-Identifier instead of the license boilerplates.
This conversion makes it easier for us to scan the license, then
I notice license mismatch problems.
The license blocks in denali* indicate GPL-2.0 "only", while the
MODULE_LICENSE in denali.c and denali_dt.c is GPL-2.0 "or later"
as explained in include/linux/module.h as follows:
"GPL" [GNU Public License v2 or later]
"GPL v2" [GNU Public License v2]
I fixed the MODULE_LICENSE tags, assuming the license blocks are
the authors' intention.
Also, add missing MODULE_DESCRIPTION/AUTHOR to denali.c
While I am touching the license things, I added my credit to denali.c
because this driver was largely re-written by me in 2017.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
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This commit improves the ->setup_data_interface() hook.
The denali_setup_data_interface() needs the frequency of clk_x
and the ratio of clk_x / clk.
The latter is currently hardcoded in the driver, like this:
#define DENALI_CLK_X_MULT 6
The IP datasheet requires that clk_x / clk be 4, 5, or 6. I just
chose 6 because it is the most defensive value, but it is not optimal.
By getting the clock rate of both "clk" and "clk_x", the driver can
compute the timing values more precisely.
To not break the existing platforms, the fallback value, 50 MHz is
provided. It is true for all upstreamed platforms.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Richard Weinberger <richard@nod.at>
Tested-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
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As part of the process of sharing more code between different NAND
based devices, we need to move all raw NAND related code to the raw/
subdirectory.
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
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