linux-kernel - [PATCH 1/7] mtd: spi-nor: Add default_init() hook to tweak flash parameters

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Message-ID: <20190731090315.26798-2-tudor.ambarus@microchip.com>
Date:   Wed, 31 Jul 2019 09:03:27 +0000
From:   <Tudor.Ambarus@...rochip.com>
To:     <boris.brezillon@...labora.com>, <marek.vasut@...il.com>,
        <vigneshr@...com>
CC:     <dwmw2@...radead.org>, <computersforpeace@...il.com>,
        <miquel.raynal@...tlin.com>, <richard@....at>,
        <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <Tudor.Ambarus@...rochip.com>
Subject: [PATCH 1/7] mtd: spi-nor: Add default_init() hook to tweak flash
 parameters

From: Tudor Ambarus <tudor.ambarus@...rochip.com>

As of now, the flash parameters initialization logic is as following:

a/ default flash parameters init in spi_nor_init_params()
b/ manufacturer specific flash parameters updates, split across entire
   spi-nor core code
c/ flash parameters updates based on SFDP tables
d/ post BFPT flash parameter updates

In the quest of removing the manufacturer specific code from the spi-nor
core, we want to impose a timeline/priority on how the flash parameters
are updated. The following sequence of calls is pursued:

1/ spi-nor core legacy flash parameters init:
	spi_nor_default_init_params()

2/ MFR-based manufacturer flash parameters init:
	nor->manufacturer->fixups->default_init()

3/ specific flash_info tweeks done when decisions can not be done just on
   MFR:
	nor->info->fixups->default_init()

4/ SFDP tables flash parameters init - SFDP knows better:
	spi_nor_sfdp_init_params()

5/ post SFDP tables flash parameters updates - in case manufacturers get
   the serial flash tables wrong or incomplete.
	nor->info->fixups->post_sfdp()
   The later can be extended to nor->manufacturer->fixups->post_sfdp() if
   needed.

This patch opens doors for steps 2/ and 3/.

Signed-off-by: Tudor Ambarus <tudor.ambarus@...rochip.com>
---
 drivers/mtd/spi-nor/spi-nor.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 28a64dbdaea9..ac00f90ebaa9 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -219,12 +219,17 @@ struct sfdp_bfpt {
 
 /**
  * struct spi_nor_fixups - SPI NOR fixup hooks
+ * @default_init: called after default flash parameters init. Used to tweak
+ *                flash parameters when information provided by the flash_info
+ *                table is incomplete or wrong.
  * @post_bfpt: called after the BFPT table has been parsed
  *
  * Those hooks can be used to tweak the SPI NOR configuration when the SFDP
  * table is broken or not available.
  */
 struct spi_nor_fixups {
+	void (*default_init)(struct spi_nor *nor,
+			     struct spi_nor_flash_parameter *params);
 	int (*post_bfpt)(struct spi_nor *nor,
 			 const struct sfdp_parameter_header *bfpt_header,
 			 const struct sfdp_bfpt *bfpt,
@@ -4267,6 +4272,14 @@ static int spi_nor_parse_sfdp(struct spi_nor *nor,
 	return err;
 }
 
+static void
+spi_nor_manufacturer_init_params(struct spi_nor *nor,
+				 struct spi_nor_flash_parameter *params)
+{
+	if (nor->info->fixups && nor->info->fixups->default_init)
+		return nor->info->fixups->default_init(nor, params);
+}
+
 static int spi_nor_init_params(struct spi_nor *nor,
 			       struct spi_nor_flash_parameter *params)
 {
@@ -4370,6 +4383,8 @@ static int spi_nor_init_params(struct spi_nor *nor,
 			params->quad_enable = info->quad_enable;
 	}
 
+	spi_nor_manufacturer_init_params(nor, params);
+
 	if ((info->flags & (SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ)) &&
 	    !(info->flags & SPI_NOR_SKIP_SFDP)) {
 		struct spi_nor_flash_parameter sfdp_params;
-- 
2.9.5