Re: [PATCH v3 05/17] mtd: spinand: Define ctrl_ops for non-page read/write op templates

From: Apurva Nandan
Date: Wed Mar 02 2022 - 10:31:29 EST

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Hi Boris,

On 15/02/22 23:07, Boris Brezillon wrote:

Hi Apurva,

On Tue, 15 Feb 2022 21:03:52 +0530
Apurva Nandan<a-nandan@xxxxxx> wrote:

Hi Boris,

On 03/01/22 15:31, Boris Brezillon wrote:

On Sat, 1 Jan 2022 13:12:38 +0530
Apurva Nandan<a-nandan@xxxxxx> wrote:

'ctrl_ops' are op templates for non-page read/write operations,
which are: reset, get_feature, set_feature, write_enable, block_erase,
page_read and program_execute ops. The 'ctrl_ops' struct contains in it
op templates for each of this op, as well as enum spinand_protocol
denoting protocol of all these ops.

We require these new op templates because of deviation in standard
SPINAND ops by manufacturers and also due to changes when there is a
change in SPI protocol/mode. This prevents the core from live-patching
and vendor-specific adjustments in ops.

Define 'ctrl_ops', add macros to initialize it and add it in
spinand_device.

Signed-off-by: Apurva Nandan<a-nandan@xxxxxx>
---
include/linux/mtd/spinand.h | 33 +++++++++++++++++++++++++++++++++
1 file changed, 33 insertions(+)

diff --git a/include/linux/mtd/spinand.h b/include/linux/mtd/spinand.h
index 439d8ce40e1d..e5df6220ec1e 100644
--- a/include/linux/mtd/spinand.h
+++ b/include/linux/mtd/spinand.h
@@ -356,6 +356,35 @@ struct spinand_op_variants {
sizeof(struct spi_mem_op), \
}
+struct spinand_ctrl_ops {
+ const struct {
+ struct spi_mem_op reset;
+ struct spi_mem_op get_feature;
+ struct spi_mem_op set_feature;
+ struct spi_mem_op write_enable;
+ struct spi_mem_op block_erase;
+ struct spi_mem_op page_read;
+ struct spi_mem_op program_execute;
+ } ops;
+ const enum spinand_protocol protocol;

Do you really need that protocol field?

+};
+
+#define SPINAND_CTRL_OPS(__protocol, __reset, __get_feature, __set_feature, \
+ __write_enable, __block_erase, __page_read, \
+ __program_execute) \
+ { \
+ .ops = { \
+ .reset = __reset, \
+ .get_feature = __get_feature, \
+ .set_feature = __set_feature, \
+ .write_enable = __write_enable, \
+ .block_erase = __block_erase, \
+ .page_read = __page_read, \
+ .program_execute = __program_execute, \
+ }, \
+ .protocol = __protocol, \
+ }
+
/**
* spinand_ecc_info - description of the on-die ECC implemented by a SPI NAND
* chip
@@ -468,6 +497,8 @@ struct spinand_dirmap {
* @data_ops.read_cache: read cache op template
* @data_ops.write_cache: write cache op template
* @data_ops.update_cache: update cache op template
+ * @ctrl_ops: various SPI mem op templates for handling the flash device, i.e.
+ * non page-read/write ops.
* @select_target: select a specific target/die. Usually called before sending
* a command addressing a page or an eraseblock embedded in
* this die. Only required if your chip exposes several dies
@@ -498,6 +529,8 @@ struct spinand_device {
const struct spi_mem_op *update_cache;
} data_ops;
+ const struct spinand_ctrl_ops *ctrl_ops;
+

Okay, I had something slightly different in mind. First, I'd put all
templates in a struct:

struct spinand_op_templates {
const struct spi_mem_op *read_cache;
const struct spi_mem_op *write_cache;
const struct spi_mem_op *update_cache;
const struct spi_mem_op *reset;
const struct spi_mem_op *get_feature;
const struct spi_mem_op *set_feature;
const struct spi_mem_op *write_enable;
const struct spi_mem_op *block_erase;
const struct spi_mem_op *page_load;
const struct spi_mem_op *program_execute;
};

Then, at the spinand level, I'd define an array of templates:

enum spinand_protocol {
SPINAND_1S_1S_1S,
SPINAND_2S_2S_2S,
SPINAND_4S_4S_4S,
SPINAND_8S_8S_8S,
SPINAND_8D_8D_8D,
SPINAND_NUM_PROTOCOLS,
};

struct spinand_device {
...
enum spinand_protocol protocol;
const struct spinand_op_templates *op_templates[SPINAND_NUM_PROTOCOLS];

It should probably be

struct spinand_op_templates op_templates[SPINAND_NUM_PROTOCOLS];

with the spinand_op_templates struct defined as:

struct spinand_op_templates {
struct spi_mem_op read_cache;
struct spi_mem_op write_cache;
struct spi_mem_op update_cache;
struct spi_mem_op reset;
struct spi_mem_op get_feature;
struct spi_mem_op set_feature;
struct spi_mem_op write_enable;
struct spi_mem_op block_erase;
struct spi_mem_op page_load;
struct spi_mem_op program_execute;
};

so the NAND framework can populate these ops.

Or maybe even better, define an enum that contains all the ops:

enum spinand_op_id {
SPI_NAND_OP_READ_CACHE,
SPI_NAND_OP_WRITE_CACHE,
SPI_NAND_OP_UPDATE_CACHE,
SPI_NAND_OP_RESET,
...
SPI_NAND_NUM_OPS,
};

struct spinand_device {
...
enum spinand_protocol protocol;
struct spi_mem_op op_templates[SPINAND_NUM_PROTOCOLS][SPI_NAND_NUM_OPS];
...
};

This way, you can easily pick the right set of operations based
on the protocol/mode you're in:

#define spinand_get_op_template(spinand, opname) \
((spinand)->op_templates[(spinand)->protocol]->opname)

static int spinand_read_reg_op(struct spinand_device *spinand, u8 reg, u8 *val)
{
struct spi_mem_op op = *spinand_get_op_template(spinand, get_feature);
int ret;

...
}

I find a couple of issues with this method,

1. read_cache, write_cache, update_cache op templates don't fit well
with the other non-data ops, as
these data ops are used to create a dirmap, and that can be done only
once at probe time. Hence, there
is a different mechanism of selecting of data ops and non-data ops.

Not sure I see why this is a problem. You can populate data-ops for all
modes, and pick the one that provides the best perfs when you create
the dirmap (which should really be at the end of the probe, if it's not
already).

Hence, this division in the op templates
struct as data_ops and ctrl_ops is required. Currently, the core only
supports using a single protocol for
data ops, chosen at the time of probing.

Again, I don't see why you need to differentiate the control and data
ops when populating this table. Those are just operations the NAND
supports, and the data operations is just a subset.

2. If we use this single op_templates struct, I can't think of any good
way to initialize these in the
manufacturers driver (winbond.c), refer to 17th patch in this series.
Could you please suggest a macro
implementation also for winbond.c with the suggested op_templates struct.

First replace the op_variants field by something more generic:

struct spinand_info {
...
const struct spinand_op_variants **ops_variants;
...
};

#define SPINAND_OP_VARIANTS(_id, ...) \
[SPI_NAND_OP_ ## _id] = { __VA_ARGS__ }

#define SPINAND_OPS_VARIANTS(name, ...)
const struct spinand_op_variants name[]{
__VA_ARGS__,
};

#define SPINAND_INFO_OPS_VARIANTS(defs)
.ops_variants = defs

...

static SPINAND_OPS_VARIANTS(w35n01jw_ops_variants,
SPINAND_OP_VARIANTS(READ_CACHE,
SPINAND_PAGE_READ_FROM_CACHE_OCTALIO_DTR_OP(0, 24, NULL, 0),
SPINAND_PAGE_READ_FROM_CACHE_OP(true, 0, 1, NULL, 0),
...)),
SPINAND_OP_VARIANTS(WRITE_CACHE,
SPINAND_PROG_LOAD_OCTALIO_DTR(true, 0, NULL, 0),
SPINAND_PROG_LOAD(true, 0, NULL, 0)),
...
SPINAND_OP_VARIANTS(RESET,
SPINAND_RESET_OP_OCTAL_DTR,
SPINAND_RESET_OP,
...
);
...

I find a issue with this implementation, please give corrective suggestions:

In type of op variant listing, there is no way to specify the protocol of the op in the variants struct itself.
    - This will lead to filtering/sorting/searching of ops for finding the protocols in the spinand core
    while in spinand_match_and_init(), which I don't feel is a good way for protocol based op categorization.
    - This would also lead to complexities in cases of mixed mode operations.
    - In addition, we can't simply choose the first supported protocol in each op id, as some ops have
    intendependency of protocol with other ops. This is because non-data ops (like reset, block erase..)
    cannot be in different protocols at same time, so it would make sense to have some form of protocol
    based arrangement while listing them.

SPINAND_INFO("W35N01JW",
SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0xdc),
NAND_MEMORG(1, 4096, 128, 64, 512, 20, 1, 1, 1),
NAND_ECCREQ(1, 512),
SPINAND_HAS_OCTAL_DTR_BIT | SPINAND_HAS_CR_FEAT_BIT,
SPINAND_ECCINFO(&w35n01jw_ooblayout, NULL),
SPINAND_INFO_OPS_VARIANTS(&w35n01jw_ops_variants)),

You also need to adjust spinand_match_and_init() to account for this
new layout and put each template op in the right subset based on
op.cmd.width and op.cmd.dtr.

Regards,

Boris

Next message: Andy Shevchenko: "[PATCH v1 1/1] iio: dac: ltc2688: Use temporary variable for struct device"
Previous message: Steven Rostedt: "Re: [PATCH] config: Using HOSTPKG_CONFIG prefix for pkg-config"
Next in thread: Boris Brezillon: "Re: [PATCH v3 05/17] mtd: spinand: Define ctrl_ops for non-page read/write op templates"
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