[PATCH] mtd: rawnand: ams-delta: Drop board specific partition info

[PATCH] mtd: rawnand: ams-delta: Drop board specific partition info

[Janusz Krzysztofik]

After recent modifications, only a hardcoded partition info makes
the driver device specific.  Other than that, the driver uses GPIO
exclusively and can be used on any hardware.

Drop the partition info and use MTD partition parser with default
list of partition types instead.

Amstrad Delta users should append the followig partition info to their
kernel command line, possibly by embedding it in CONFIG_CMDLINE:
mtdparts=ams-delta-nand:3584k(Kernel),256k(u-boot),256k(u-boot_params),\
256k(Amstrad_LDR),27m(File_system),768k(PBL_reserved).  For their
convenience, select CONFIG_MTD_CMDLINE_PARTS  symbol from that board
Kconfig automatically if this NAND driver is also selected.

Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>
---
 arch/arm/mach-omap1/Kconfig      |  1 +
 drivers/mtd/nand/raw/ams-delta.c | 28 +---------------------------
 2 files changed, 2 insertions(+), 27 deletions(-)

diff --git a/arch/arm/mach-omap1/Kconfig b/arch/arm/mach-omap1/Kconfig
index c4694f26b5c4..62cf20f22828 100644
--- a/arch/arm/mach-omap1/Kconfig
+++ b/arch/arm/mach-omap1/Kconfig
@@ -171,6 +171,7 @@ config MACH_AMS_DELTA
 	select LEDS_GPIO_REGISTER
 	select REGULATOR
 	select REGULATOR_FIXED_VOLTAGE
+	select MTD_CMDLINE_PARTS if MTD_NAND_AMS_DELTA
 	help
 	  Support for the Amstrad E3 (codename Delta) videophone. Say Y here
 	  if you have such a device.
diff --git a/drivers/mtd/nand/raw/ams-delta.c b/drivers/mtd/nand/raw/ams-delta.c
index 8312182088c1..2e8e37ea549a 100644
--- a/drivers/mtd/nand/raw/ams-delta.c
+++ b/drivers/mtd/nand/raw/ams-delta.c
@@ -41,31 +41,6 @@ struct ams_delta_nand {
 	bool			data_in;
 };
 
-/*
- * Define partitions for flash devices
- */
-
-static const struct mtd_partition partition_info[] = {
-	{ .name		= "Kernel",
-	  .offset	= 0,
-	  .size		= 3 * SZ_1M + SZ_512K },
-	{ .name		= "u-boot",
-	  .offset	= 3 * SZ_1M + SZ_512K,
-	  .size		= SZ_256K },
-	{ .name		= "u-boot params",
-	  .offset	= 3 * SZ_1M + SZ_512K + SZ_256K,
-	  .size		= SZ_256K },
-	{ .name		= "Amstrad LDR",
-	  .offset	= 4 * SZ_1M,
-	  .size		= SZ_256K },
-	{ .name		= "File system",
-	  .offset	= 4 * SZ_1M + 1 * SZ_256K,
-	  .size		= 27 * SZ_1M },
-	{ .name		= "PBL reserved",
-	  .offset	= 32 * SZ_1M - 3 * SZ_256K,
-	  .size		=  3 * SZ_256K },
-};
-
 static void ams_delta_write_commit(struct ams_delta_nand *priv)
 {
 	gpiod_set_value(priv->gpiod_nwe, 0);
@@ -315,8 +290,7 @@ static int ams_delta_init(struct platform_device *pdev)
 		return err;
 
 	/* Register the partitions */
-	err = mtd_device_register(mtd, partition_info,
-				  ARRAY_SIZE(partition_info));
+	err = mtd_device_parse_register(mtd, NULL, NULL, NULL, 0);
 	if (err)
 		goto err_nand_cleanup;
 
-- 
2.19.2

Re: [PATCH] mtd: rawnand: ams-delta: Drop board specific partition info

[Aaro Koskinen]

On Tue, Mar 19, 2019 at 11:37:18PM +0100, Janusz Krzysztofik wrote:
> After recent modifications, only a hardcoded partition info makes
> the driver device specific.  Other than that, the driver uses GPIO
> exclusively and can be used on any hardware.
> 
> Drop the partition info and use MTD partition parser with default
> list of partition types instead.
> 
> Amstrad Delta users should append the followig partition info to their
                                        ^^^^^^^^
Should be "following".

> kernel command line, possibly by embedding it in CONFIG_CMDLINE:
> mtdparts=ams-delta-nand:3584k(Kernel),256k(u-boot),256k(u-boot_params),\
> 256k(Amstrad_LDR),27m(File_system),768k(PBL_reserved).  For their
> convenience, select CONFIG_MTD_CMDLINE_PARTS  symbol from that board
> Kconfig automatically if this NAND driver is also selected.
> 
> Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
> Cc: Tony Lindgren <tony@atomide.com>

Could we move the fixed partition setup to the board file
instead? Otherwise this kind of change is not really nice for the users,
as it will likely break existing setups. The default partition layout
should remain the same.

A.

Re: [PATCH] mtd: rawnand: ams-delta: Drop board specific partition info

[Janusz Krzysztofik]

Hi Aaro,

Thanks for your review.

On Wednesday, March 20, 2019 2:16:30 AM CET Aaro Koskinen wrote:
> On Tue, Mar 19, 2019 at 11:37:18PM +0100, Janusz Krzysztofik wrote:
> > After recent modifications, only a hardcoded partition info makes
> > the driver device specific.  Other than that, the driver uses GPIO
> > exclusively and can be used on any hardware.
> > 
> > Drop the partition info and use MTD partition parser with default
> > list of partition types instead.
> > 
> > Amstrad Delta users should append the followig partition info to their
>                                         ^^^^^^^^
> Should be "following".
> 
> > kernel command line, possibly by embedding it in CONFIG_CMDLINE:
> > mtdparts=ams-delta-nand:3584k(Kernel),256k(u-boot),256k(u-boot_params),\
> > 256k(Amstrad_LDR),27m(File_system),768k(PBL_reserved).  For their
> > convenience, select CONFIG_MTD_CMDLINE_PARTS  symbol from that board
> > Kconfig automatically if this NAND driver is also selected.
> > 
> > Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
> > Cc: Tony Lindgren <tony@atomide.com>
> 
> Could we move the fixed partition setup to the board file
> instead? Otherwise this kind of change is not really nice for the users,
> as it will likely break existing setups. The default partition layout
> should remain the same.

I'm wondering if it would be acceptable to pass partition info from a .dts 
file.  I think that would be a better, more modern approach than adding a new 
header under include/linux/platform_data.

The problem with a device tree based implementation is, I know of no u-boot 
version supporting both Amstrad Delta and FDT.  However, I've already tested 
two solutions that work for me.

One uses CONFIG_ARM_APPENDED_DTB and requires a user to manually append the 
blob to zImage and (re)generate uImage.  I'm not sure how much more user-
friendly it looks for you, compared to the command line version I proposed 
initially.

If the above is not acceptable. I can propose still another approach. The blob 
is automagically built and embedded into the kernel with some assembler glue, 
then unflattened from the board init_machine(), somehow similar to the way 
drivers/of/unittest.c does it.

Please advise which approach sounds best to you (platform_data, 
CONFIG_ARM_APPENDED_DTB or unittest like).

Thanks,
Janusz


> 
> A.
> 

Re: [PATCH] mtd: rawnand: ams-delta: Drop board specific partition info

[Aaro Koskinen]

Hi,

On Sun, Mar 24, 2019 at 05:48:22PM +0100, Janusz Krzysztofik wrote:
> Hi Aaro,
> 
> Thanks for your review.
> 
> On Wednesday, March 20, 2019 2:16:30 AM CET Aaro Koskinen wrote:
> > On Tue, Mar 19, 2019 at 11:37:18PM +0100, Janusz Krzysztofik wrote:
> > > After recent modifications, only a hardcoded partition info makes
> > > the driver device specific.  Other than that, the driver uses GPIO
> > > exclusively and can be used on any hardware.
> > > 
> > > Drop the partition info and use MTD partition parser with default
> > > list of partition types instead.
> > > 
> > > Amstrad Delta users should append the followig partition info to their
> >                                         ^^^^^^^^
> > Should be "following".
> > 
> > > kernel command line, possibly by embedding it in CONFIG_CMDLINE:
> > > mtdparts=ams-delta-nand:3584k(Kernel),256k(u-boot),256k(u-boot_params),\
> > > 256k(Amstrad_LDR),27m(File_system),768k(PBL_reserved).  For their
> > > convenience, select CONFIG_MTD_CMDLINE_PARTS  symbol from that board
> > > Kconfig automatically if this NAND driver is also selected.
> > > 
> > > Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
> > > Cc: Tony Lindgren <tony@atomide.com>
> > 
> > Could we move the fixed partition setup to the board file
> > instead? Otherwise this kind of change is not really nice for the users,
> > as it will likely break existing setups. The default partition layout
> > should remain the same.
> 
> I'm wondering if it would be acceptable to pass partition info from a .dts 
> file.  I think that would be a better, more modern approach than adding a new 
> header under include/linux/platform_data.

Hmm, I thought there was some generic way to define partitions without
adding any new headers. But if that is not possible, then I guess your
CMDLINE proposal is the preferred one..

A.

Re: [PATCH] mtd: rawnand: ams-delta: Drop board specific partition info

[H. Nikolaus Schaller]

Hi,

> Am 24.03.2019 um 19:59 schrieb Aaro Koskinen <aaro.koskinen@iki.fi>:
> 
> Hi,
> 
> On Sun, Mar 24, 2019 at 05:48:22PM +0100, Janusz Krzysztofik wrote:
>> Hi Aaro,
>> 
>> Thanks for your review.
>> 
>> On Wednesday, March 20, 2019 2:16:30 AM CET Aaro Koskinen wrote:
>>> On Tue, Mar 19, 2019 at 11:37:18PM +0100, Janusz Krzysztofik wrote:
>>>> After recent modifications, only a hardcoded partition info makes
>>>> the driver device specific.  Other than that, the driver uses GPIO
>>>> exclusively and can be used on any hardware.
>>>> 
>>>> Drop the partition info and use MTD partition parser with default
>>>> list of partition types instead.
>>>> 
>>>> Amstrad Delta users should append the followig partition info to their
>>>                                        ^^^^^^^^
>>> Should be "following".
>>> 
>>>> kernel command line, possibly by embedding it in CONFIG_CMDLINE:
>>>> mtdparts=ams-delta-nand:3584k(Kernel),256k(u-boot),256k(u-boot_params),\
>>>> 256k(Amstrad_LDR),27m(File_system),768k(PBL_reserved).  For their
>>>> convenience, select CONFIG_MTD_CMDLINE_PARTS  symbol from that board
>>>> Kconfig automatically if this NAND driver is also selected.
>>>> 
>>>> Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
>>>> Cc: Tony Lindgren <tony@atomide.com>
>>> 
>>> Could we move the fixed partition setup to the board file
>>> instead? Otherwise this kind of change is not really nice for the users,
>>> as it will likely break existing setups. The default partition layout
>>> should remain the same.
>> 
>> I'm wondering if it would be acceptable to pass partition info from a .dts 
>> file.  I think that would be a better, more modern approach than adding a new 
>> header under include/linux/platform_data.
> 
> Hmm, I thought there was some generic way to define partitions without
> adding any new headers. But if that is not possible, then I guess your
> CMDLINE proposal is the preferred one..

I am not sure what you exactly need, but partitions can be defined in
the DTS as children of some NAND drivers. Example:
arch/arm/boot/dts/omap3-beagle.dts
So this design pattern could be copied instead of using CMDLINE.

Re: [PATCH] mtd: rawnand: ams-delta: Drop board specific partition info

[Janusz Krzysztofik]

Hi,

On Sunday, March 24, 2019 8:24:48 PM CET H. Nikolaus Schaller wrote:
> Hi,
> 
> > Am 24.03.2019 um 19:59 schrieb Aaro Koskinen <aaro.koskinen@iki.fi>:
> > 
> > Hi,
> > 
> > On Sun, Mar 24, 2019 at 05:48:22PM +0100, Janusz Krzysztofik wrote:
> >> Hi Aaro,
> >> 
> >> Thanks for your review.
> >> 
> >> On Wednesday, March 20, 2019 2:16:30 AM CET Aaro Koskinen wrote:
> >>> On Tue, Mar 19, 2019 at 11:37:18PM +0100, Janusz Krzysztofik wrote:
> >>>> After recent modifications, only a hardcoded partition info makes
> >>>> the driver device specific.  Other than that, the driver uses GPIO
> >>>> exclusively and can be used on any hardware.
> >>>> 
> >>>> Drop the partition info and use MTD partition parser with default
> >>>> list of partition types instead.
> >>>> 
> >>>> Amstrad Delta users should append the followig partition info to their
> >>>                                        ^^^^^^^^
> >>> Should be "following".
> >>> 
> >>>> kernel command line, possibly by embedding it in CONFIG_CMDLINE:
> >>>> mtdparts=ams-delta-nand:3584k(Kernel),256k(u-boot),256k(u-boot_params),
\
> >>>> 256k(Amstrad_LDR),27m(File_system),768k(PBL_reserved).  For their
> >>>> convenience, select CONFIG_MTD_CMDLINE_PARTS  symbol from that board
> >>>> Kconfig automatically if this NAND driver is also selected.
> >>>> 
> >>>> Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
> >>>> Cc: Tony Lindgren <tony@atomide.com>
> >>> 
> >>> Could we move the fixed partition setup to the board file
> >>> instead? Otherwise this kind of change is not really nice for the users,
> >>> as it will likely break existing setups. The default partition layout
> >>> should remain the same.
> >> 
> >> I'm wondering if it would be acceptable to pass partition info from a 
.dts 
> >> file.  I think that would be a better, more modern approach than adding a 
new 
> >> header under include/linux/platform_data.
> > 
> > Hmm, I thought there was some generic way to define partitions without
> > adding any new headers. But if that is not possible, then I guess your
> > CMDLINE proposal is the preferred one..
> 
> I am not sure what you exactly need, but partitions can be defined in
> the DTS as children of some NAND drivers. Example:
> arch/arm/boot/dts/omap3-beagle.dts
> So this design pattern could be copied instead of using CMDLINE.

The problem is, OMAP1 has no device tree support.  Other than that, your 
proposed approach already works for me locally with some basic support for 
device tree added to the board file.

Thanks,
Janusz

Re: [PATCH] mtd: rawnand: ams-delta: Drop board specific partition info

[Janusz Krzysztofik]

Hi,

On Sunday, March 24, 2019 7:59:32 PM CET Aaro Koskinen wrote:
> Hi,
> 
> On Sun, Mar 24, 2019 at 05:48:22PM +0100, Janusz Krzysztofik wrote:
> > Hi Aaro,
> > 
> > Thanks for your review.
> > 
> > On Wednesday, March 20, 2019 2:16:30 AM CET Aaro Koskinen wrote:
> > > On Tue, Mar 19, 2019 at 11:37:18PM +0100, Janusz Krzysztofik wrote:
> > > > After recent modifications, only a hardcoded partition info makes
> > > > the driver device specific.  Other than that, the driver uses GPIO
> > > > exclusively and can be used on any hardware.
> > > > 
> > > > Drop the partition info and use MTD partition parser with default
> > > > list of partition types instead.
> > > > 
> > > > Amstrad Delta users should append the followig partition info to their
> > >                                         ^^^^^^^^
> > > Should be "following".
> > > 
> > > > kernel command line, possibly by embedding it in CONFIG_CMDLINE:
> > > > mtdparts=ams-delta-nand:3584k(Kernel),256k(u-boot),256k(u-
boot_params),\
> > > > 256k(Amstrad_LDR),27m(File_system),768k(PBL_reserved).  For their
> > > > convenience, select CONFIG_MTD_CMDLINE_PARTS  symbol from that board
> > > > Kconfig automatically if this NAND driver is also selected.
> > > > 
> > > > Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
> > > > Cc: Tony Lindgren <tony@atomide.com>
> > > 
> > > Could we move the fixed partition setup to the board file
> > > instead? Otherwise this kind of change is not really nice for the users,
> > > as it will likely break existing setups. The default partition layout
> > > should remain the same.
> > 
> > I'm wondering if it would be acceptable to pass partition info from a .dts 
> > file.  I think that would be a better, more modern approach than adding a 
new 
> > header under include/linux/platform_data.
> 
> Hmm, I thought there was some generic way to define partitions without
> adding any new headers. But if that is not possible, then I guess your
> CMDLINE proposal is the preferred one..

I could for example reuse (or abuse) struct gpio_nand_platdata defined in 
include/linux/mtd/nand-gpio.h for use with drivers/mtd/nand/raw/gpio.c, but 
I'm not sure if hi-jacking a header that belongs to another driver would be an 
elegant solution.

Thanks,
Janusz


> 
> A.
> 

[PATCH v2] mtd: rawnand: ams-delta: Drop board specific partition info

[Janusz Krzysztofik]

After recent modifications, only a hardcoded partition info makes
the driver device specific.  Other than that, the driver uses GPIO
exclusively and can be used on any hardware.

Drop the partition info and use MTD partition parser with default list
of parser names instead.  For the OF parser to work correctly, pass
device of_node to mtd.

Amstrad Delta users should append the following partition info to their
kernel command line, possibly by embedding it in CONFIG_CMDLINE:

mtdparts=ams-delta-nand:3584k(Kernel),256k(u-boot),256k(u-boot_params),\
256k(Amstrad_LDR),27m(File_system),768k(PBL_reserved).

For their convenience, CONFIG_MTD_CMDLINE_PARTS symbol is selected
automatically from that board Kconfig if this NAND driver is also
selected.

Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>
---
CHangelog:
v1->v2:
- fix a typo poined out by Aaro - thanks!
- fix device_node not passed to OF parser via mtd_info
- commit message reworded and reformatted a bit for better readability

 arch/arm/mach-omap1/Kconfig      |  1 +
 drivers/mtd/nand/raw/ams-delta.c | 29 ++---------------------------
 2 files changed, 3 insertions(+), 27 deletions(-)

diff --git a/arch/arm/mach-omap1/Kconfig b/arch/arm/mach-omap1/Kconfig
index c4694f26b5c4..62cf20f22828 100644
--- a/arch/arm/mach-omap1/Kconfig
+++ b/arch/arm/mach-omap1/Kconfig
@@ -171,6 +171,7 @@ config MACH_AMS_DELTA
 	select LEDS_GPIO_REGISTER
 	select REGULATOR
 	select REGULATOR_FIXED_VOLTAGE
+	select MTD_CMDLINE_PARTS if MTD_NAND_AMS_DELTA
 	help
 	  Support for the Amstrad E3 (codename Delta) videophone. Say Y here
 	  if you have such a device.
diff --git a/drivers/mtd/nand/raw/ams-delta.c b/drivers/mtd/nand/raw/ams-delta.c
index 8312182088c1..e0f09179bbda 100644
--- a/drivers/mtd/nand/raw/ams-delta.c
+++ b/drivers/mtd/nand/raw/ams-delta.c
@@ -41,31 +41,6 @@ struct ams_delta_nand {
 	bool			data_in;
 };
 
-/*
- * Define partitions for flash devices
- */
-
-static const struct mtd_partition partition_info[] = {
-	{ .name		= "Kernel",
-	  .offset	= 0,
-	  .size		= 3 * SZ_1M + SZ_512K },
-	{ .name		= "u-boot",
-	  .offset	= 3 * SZ_1M + SZ_512K,
-	  .size		= SZ_256K },
-	{ .name		= "u-boot params",
-	  .offset	= 3 * SZ_1M + SZ_512K + SZ_256K,
-	  .size		= SZ_256K },
-	{ .name		= "Amstrad LDR",
-	  .offset	= 4 * SZ_1M,
-	  .size		= SZ_256K },
-	{ .name		= "File system",
-	  .offset	= 4 * SZ_1M + 1 * SZ_256K,
-	  .size		= 27 * SZ_1M },
-	{ .name		= "PBL reserved",
-	  .offset	= 32 * SZ_1M - 3 * SZ_256K,
-	  .size		=  3 * SZ_256K },
-};
-
 static void ams_delta_write_commit(struct ams_delta_nand *priv)
 {
 	gpiod_set_value(priv->gpiod_nwe, 0);
@@ -238,6 +213,7 @@ static int ams_delta_init(struct platform_device *pdev)
 	mtd->dev.parent = &pdev->dev;
 
 	nand_set_controller_data(this, priv);
+	nand_set_flash_node(this, pdev->dev.of_node);
 
 	priv->gpiod_rdy = devm_gpiod_get_optional(&pdev->dev, "rdy", GPIOD_IN);
 	if (IS_ERR(priv->gpiod_rdy)) {
@@ -315,8 +291,7 @@ static int ams_delta_init(struct platform_device *pdev)
 		return err;
 
 	/* Register the partitions */
-	err = mtd_device_register(mtd, partition_info,
-				  ARRAY_SIZE(partition_info));
+	err = mtd_device_parse_register(mtd, NULL, NULL, NULL, 0);
 	if (err)
 		goto err_nand_cleanup;
 
-- 
2.19.2

Re: [PATCH v2] mtd: rawnand: ams-delta: Drop board specific partition info

[Miquel Raynal]

Hi Janusz,

Janusz Krzysztofik <jmkrzyszt@gmail.com> wrote on Sun, 24 Mar 2019
23:33:44 +0100:

> After recent modifications, only a hardcoded partition info makes
> the driver device specific.  Other than that, the driver uses GPIO
> exclusively and can be used on any hardware.
> 
> Drop the partition info and use MTD partition parser with default list
> of parser names instead.  For the OF parser to work correctly, pass
> device of_node to mtd.
> 
> Amstrad Delta users should append the following partition info to their
> kernel command line, possibly by embedding it in CONFIG_CMDLINE:
> 
> mtdparts=ams-delta-nand:3584k(Kernel),256k(u-boot),256k(u-boot_params),\
> 256k(Amstrad_LDR),27m(File_system),768k(PBL_reserved).
> 
> For their convenience, CONFIG_MTD_CMDLINE_PARTS symbol is selected
> automatically from that board Kconfig if this NAND driver is also
> selected.
> 
> Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
> Cc: Tony Lindgren <tony@atomide.com>
> ---

FYI I am okay with the change but I am waiting for acks before applying
it.

Thanks,
Miquèl

Re: [PATCH v2] mtd: rawnand: ams-delta: Drop board specific partition info

[Janusz Krzysztofik]

Hi Aaro, Tony,

On Wednesday, April 17, 2019 11:40:10 AM CEST Miquel Raynal wrote:
> Hi Janusz,
> 
> Janusz Krzysztofik <jmkrzyszt@gmail.com> wrote on Sun, 24 Mar 2019
> 23:33:44 +0100:
> 
> > After recent modifications, only a hardcoded partition info makes
> > the driver device specific.  Other than that, the driver uses GPIO
> > exclusively and can be used on any hardware.
> > 
> > Drop the partition info and use MTD partition parser with default list
> > of parser names instead.  For the OF parser to work correctly, pass
> > device of_node to mtd.
> > 
> > Amstrad Delta users should append the following partition info to their
> > kernel command line, possibly by embedding it in CONFIG_CMDLINE:
> > 
> > mtdparts=ams-delta-nand:3584k(Kernel),256k(u-boot),256k(u-boot_params),\
> > 256k(Amstrad_LDR),27m(File_system),768k(PBL_reserved).
> > 
> > For their convenience, CONFIG_MTD_CMDLINE_PARTS symbol is selected
> > automatically from that board Kconfig if this NAND driver is also
> > selected.
> > 
> > Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
> > Cc: Tony Lindgren <tony@atomide.com>
> > ---
> 
> FYI I am okay with the change but I am waiting for acks before applying
> it.

May we have an ack from you?

If still not convinced with my clarifications, I can add a comment to help text 
in Kconfig, either squashed or in a follow up patch, on the requirement of 
appending mtdparts parameter to command line.  What do you think?

Thanks,
Janusz

> 
> Thanks,
> Miquèl
> 

Re: [PATCH v2] mtd: rawnand: ams-delta: Drop board specific partition info

[Miquel Raynal]

Hi Janusz,

Janusz Krzysztofik <jmkrzyszt@gmail.com> wrote on Thu, 18 Apr 2019
01:09:59 +0200:

> Hi Aaro, Tony,
> 
> On Wednesday, April 17, 2019 11:40:10 AM CEST Miquel Raynal wrote:
> > Hi Janusz,
> > 
> > Janusz Krzysztofik <jmkrzyszt@gmail.com> wrote on Sun, 24 Mar 2019
> > 23:33:44 +0100:
> >   
> > > After recent modifications, only a hardcoded partition info makes
> > > the driver device specific.  Other than that, the driver uses GPIO
> > > exclusively and can be used on any hardware.
> > > 
> > > Drop the partition info and use MTD partition parser with default list
> > > of parser names instead.  For the OF parser to work correctly, pass
> > > device of_node to mtd.
> > > 
> > > Amstrad Delta users should append the following partition info to their
> > > kernel command line, possibly by embedding it in CONFIG_CMDLINE:
> > > 
> > > mtdparts=ams-delta-nand:3584k(Kernel),256k(u-boot),256k(u-boot_params),\
> > > 256k(Amstrad_LDR),27m(File_system),768k(PBL_reserved).
> > > 
> > > For their convenience, CONFIG_MTD_CMDLINE_PARTS symbol is selected
> > > automatically from that board Kconfig if this NAND driver is also
> > > selected.
> > > 
> > > Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
> > > Cc: Tony Lindgren <tony@atomide.com>
> > > ---  
> > 
> > FYI I am okay with the change but I am waiting for acks before applying
> > it.  
> 
> May we have an ack from you?
> 
> If still not convinced with my clarifications, I can add a comment to help text 
> in Kconfig, either squashed or in a follow up patch, on the requirement of 
> appending mtdparts parameter to command line.  What do you think?

In the same patch I guess that would be fine.

Thanks,
Miquèl

Re: [PATCH v2] mtd: rawnand: ams-delta: Drop board specific partition info

[Janusz Krzysztofik]

Hi Miquèl,

I'm wondering if we could register up a custom mtd partition parser from the 
board file.  It could return a pointer to a statically defined table.  Then we 
could add its name to the list of parsers the driver is going to try if the 
board is enabled in .config.
Would that be acceptable from the MTD subsystem point of view?

Thanks,
Janusz


On Thursday, April 18, 2019 8:49:29 AM CEST Miquel Raynal wrote:
> Hi Janusz,
> 
> Janusz Krzysztofik <jmkrzyszt@gmail.com> wrote on Thu, 18 Apr 2019
> 01:09:59 +0200:
> 
> > Hi Aaro, Tony,
> > 
> > On Wednesday, April 17, 2019 11:40:10 AM CEST Miquel Raynal wrote:
> > > Hi Janusz,
> > > 
> > > Janusz Krzysztofik <jmkrzyszt@gmail.com> wrote on Sun, 24 Mar 2019
> > > 23:33:44 +0100:
> > >   
> > > > After recent modifications, only a hardcoded partition info makes
> > > > the driver device specific.  Other than that, the driver uses GPIO
> > > > exclusively and can be used on any hardware.
> > > > 
> > > > Drop the partition info and use MTD partition parser with default list
> > > > of parser names instead.  For the OF parser to work correctly, pass
> > > > device of_node to mtd.
> > > > 
> > > > Amstrad Delta users should append the following partition info to 
their
> > > > kernel command line, possibly by embedding it in CONFIG_CMDLINE:
> > > > 
> > > > mtdparts=ams-delta-nand:3584k(Kernel),256k(u-boot),256k(u-
boot_params),\
> > > > 256k(Amstrad_LDR),27m(File_system),768k(PBL_reserved).
> > > > 
> > > > For their convenience, CONFIG_MTD_CMDLINE_PARTS symbol is selected
> > > > automatically from that board Kconfig if this NAND driver is also
> > > > selected.
> > > > 
> > > > Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
> > > > Cc: Tony Lindgren <tony@atomide.com>
> > > > ---  
> > > 
> > > FYI I am okay with the change but I am waiting for acks before applying
> > > it.  
> > 
> > May we have an ack from you?
> > 
> > If still not convinced with my clarifications, I can add a comment to help 
text 
> > in Kconfig, either squashed or in a follow up patch, on the requirement of 
> > appending mtdparts parameter to command line.  What do you think?
> 
> In the same patch I guess that would be fine.
> 
> Thanks,
> Miquèl
> 

[PATCH v3] mtd: rawnand: ams-delta: Drop board specific partition info

[Janusz Krzysztofik]

After recent modifications, only a hardcoded partition info makes
the driver device specific.  Other than that, the driver uses GPIO
exclusively and can be used on any hardware.

Drop the partition info and use MTD partition parser with default list
of parser names instead.  For the OF parser to work correctly, pass
device of_node to mtd.

Amstrad Delta users should append the following partition info to their
kernel command line, possibly embedding it in CONFIG_CMDLINE:

mtdparts=ams-delta-nand:3584k(Kernel),256k(u-boot),256k(u-boot_params),\
256k(Amstrad_LDR),27m(File_system),768k(PBL_reserved)

For their convenience, that information is added to the board Kconfig
entry help text, as well as CONFIG_MTD_CMDLINE_PARTS symbol is selected
automatically from the board Kconfig entry if the NAND driver is also
selected.

Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Aaro Koskinen <aaro.koskinen@iki.fi>
---
Changelog:
v2->v3:
- add information on the requirement for passing partition info via
  kernel command line to the board Kconfig entry help text
v1->v2:
- fix a typo poitned out by Aaro - thanks!
- fix device_node not passed to OF parser via mtd_info
- commit message reworded and reformatted a bit for better readability

 arch/arm/mach-omap1/Kconfig      |  7 ++++++-
 drivers/mtd/nand/raw/ams-delta.c | 29 ++---------------------------
 2 files changed, 8 insertions(+), 28 deletions(-)

diff --git a/arch/arm/mach-omap1/Kconfig b/arch/arm/mach-omap1/Kconfig
index c4694f26b5c4..41a47d251cac 100644
--- a/arch/arm/mach-omap1/Kconfig
+++ b/arch/arm/mach-omap1/Kconfig
@@ -164,17 +164,22 @@ config MACH_NOKIA770
 	  have such a device.
 
 config MACH_AMS_DELTA
-	bool "Amstrad E3 (Delta)"
+	bool "Amstrad E3 (Delta) - see help for important information"
 	depends on ARCH_OMAP1 && ARCH_OMAP15XX
 	select FIQ
 	select GPIO_GENERIC_PLATFORM
 	select LEDS_GPIO_REGISTER
 	select REGULATOR
 	select REGULATOR_FIXED_VOLTAGE
+	select MTD_CMDLINE_PARTS if MTD_NAND_AMS_DELTA
 	help
 	  Support for the Amstrad E3 (codename Delta) videophone. Say Y here
 	  if you have such a device.
 
+	  If you are using built-in NAND, append the following partition
+	  info to kernel command line:
+	  mtdparts=ams-delta-nand:3584k(Kernel),256k(u-boot),256k(u-boot_params),256k(Amstrad_LDR),27m(File_system),768k(PBL_reserved)
+
 config MACH_OMAP_GENERIC
 	bool "Generic OMAP board"
 	depends on ARCH_OMAP1 && (ARCH_OMAP15XX || ARCH_OMAP16XX)
diff --git a/drivers/mtd/nand/raw/ams-delta.c b/drivers/mtd/nand/raw/ams-delta.c
index 8312182088c1..e0f09179bbda 100644
--- a/drivers/mtd/nand/raw/ams-delta.c
+++ b/drivers/mtd/nand/raw/ams-delta.c
@@ -41,31 +41,6 @@ struct ams_delta_nand {
 	bool			data_in;
 };
 
-/*
- * Define partitions for flash devices
- */
-
-static const struct mtd_partition partition_info[] = {
-	{ .name		= "Kernel",
-	  .offset	= 0,
-	  .size		= 3 * SZ_1M + SZ_512K },
-	{ .name		= "u-boot",
-	  .offset	= 3 * SZ_1M + SZ_512K,
-	  .size		= SZ_256K },
-	{ .name		= "u-boot params",
-	  .offset	= 3 * SZ_1M + SZ_512K + SZ_256K,
-	  .size		= SZ_256K },
-	{ .name		= "Amstrad LDR",
-	  .offset	= 4 * SZ_1M,
-	  .size		= SZ_256K },
-	{ .name		= "File system",
-	  .offset	= 4 * SZ_1M + 1 * SZ_256K,
-	  .size		= 27 * SZ_1M },
-	{ .name		= "PBL reserved",
-	  .offset	= 32 * SZ_1M - 3 * SZ_256K,
-	  .size		=  3 * SZ_256K },
-};
-
 static void ams_delta_write_commit(struct ams_delta_nand *priv)
 {
 	gpiod_set_value(priv->gpiod_nwe, 0);
@@ -238,6 +213,7 @@ static int ams_delta_init(struct platform_device *pdev)
 	mtd->dev.parent = &pdev->dev;
 
 	nand_set_controller_data(this, priv);
+	nand_set_flash_node(this, pdev->dev.of_node);
 
 	priv->gpiod_rdy = devm_gpiod_get_optional(&pdev->dev, "rdy", GPIOD_IN);
 	if (IS_ERR(priv->gpiod_rdy)) {
@@ -315,8 +291,7 @@ static int ams_delta_init(struct platform_device *pdev)
 		return err;
 
 	/* Register the partitions */
-	err = mtd_device_register(mtd, partition_info,
-				  ARRAY_SIZE(partition_info));
+	err = mtd_device_parse_register(mtd, NULL, NULL, NULL, 0);
 	if (err)
 		goto err_nand_cleanup;
 
-- 
2.21.0

Re: [PATCH v3] mtd: rawnand: ams-delta: Drop board specific partition info

[Ladislav Michl]

Hi Janusz,

On Wed, Apr 24, 2019 at 08:02:12PM +0200, Janusz Krzysztofik wrote:
> After recent modifications, only a hardcoded partition info makes
> the driver device specific.  Other than that, the driver uses GPIO
> exclusively and can be used on any hardware.
> 
> Drop the partition info and use MTD partition parser with default list
> of parser names instead.  For the OF parser to work correctly, pass
> device of_node to mtd.
> 
> Amstrad Delta users should append the following partition info to their
> kernel command line, possibly embedding it in CONFIG_CMDLINE:
> 
> mtdparts=ams-delta-nand:3584k(Kernel),256k(u-boot),256k(u-boot_params),\
> 256k(Amstrad_LDR),27m(File_system),768k(PBL_reserved)

now, when driver is no longer Amstrad Delta specific, why would you want
to have ams-delta-nand hardcoded on kernel cmdline? I'm assuming at some
point this driver will become gpio-nand [*] or something like that and
asking users to change their kernel cmdline twice is just unwise :)

[*] btw, it is really shame gpio-nand name is already taken by driver
living in drivers/mtd/nand/raw/gpio.c which is more likely gpio-mem-nand
used by at least CompuLab CM-X255 and Picochip picoXcell.

Otherwise your work on this driver is so amazing that I just spent
couple of hours finding that phone and compiling some decent userspace
for it :) Thank you!

> For their convenience, that information is added to the board Kconfig
> entry help text, as well as CONFIG_MTD_CMDLINE_PARTS symbol is selected
> automatically from the board Kconfig entry if the NAND driver is also
> selected.
> 
> Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
> Cc: Tony Lindgren <tony@atomide.com>
> Cc: Aaro Koskinen <aaro.koskinen@iki.fi>
> ---
> Changelog:
> v2->v3:
> - add information on the requirement for passing partition info via
>   kernel command line to the board Kconfig entry help text
> v1->v2:
> - fix a typo poitned out by Aaro - thanks!
> - fix device_node not passed to OF parser via mtd_info
> - commit message reworded and reformatted a bit for better readability
> 
>  arch/arm/mach-omap1/Kconfig      |  7 ++++++-
>  drivers/mtd/nand/raw/ams-delta.c | 29 ++---------------------------
>  2 files changed, 8 insertions(+), 28 deletions(-)
> 
> diff --git a/arch/arm/mach-omap1/Kconfig b/arch/arm/mach-omap1/Kconfig
> index c4694f26b5c4..41a47d251cac 100644
> --- a/arch/arm/mach-omap1/Kconfig
> +++ b/arch/arm/mach-omap1/Kconfig
> @@ -164,17 +164,22 @@ config MACH_NOKIA770
>  	  have such a device.
>  
>  config MACH_AMS_DELTA
> -	bool "Amstrad E3 (Delta)"
> +	bool "Amstrad E3 (Delta) - see help for important information"
>  	depends on ARCH_OMAP1 && ARCH_OMAP15XX
>  	select FIQ
>  	select GPIO_GENERIC_PLATFORM
>  	select LEDS_GPIO_REGISTER
>  	select REGULATOR
>  	select REGULATOR_FIXED_VOLTAGE
> +	select MTD_CMDLINE_PARTS if MTD_NAND_AMS_DELTA
>  	help
>  	  Support for the Amstrad E3 (codename Delta) videophone. Say Y here
>  	  if you have such a device.
>  
> +	  If you are using built-in NAND, append the following partition
> +	  info to kernel command line:
> +	  mtdparts=ams-delta-nand:3584k(Kernel),256k(u-boot),256k(u-boot_params),256k(Amstrad_LDR),27m(File_system),768k(PBL_reserved)
> +
>  config MACH_OMAP_GENERIC
>  	bool "Generic OMAP board"
>  	depends on ARCH_OMAP1 && (ARCH_OMAP15XX || ARCH_OMAP16XX)
> diff --git a/drivers/mtd/nand/raw/ams-delta.c b/drivers/mtd/nand/raw/ams-delta.c
> index 8312182088c1..e0f09179bbda 100644
> --- a/drivers/mtd/nand/raw/ams-delta.c
> +++ b/drivers/mtd/nand/raw/ams-delta.c
> @@ -41,31 +41,6 @@ struct ams_delta_nand {
>  	bool			data_in;
>  };
>  
> -/*
> - * Define partitions for flash devices
> - */
> -
> -static const struct mtd_partition partition_info[] = {
> -	{ .name		= "Kernel",
> -	  .offset	= 0,
> -	  .size		= 3 * SZ_1M + SZ_512K },
> -	{ .name		= "u-boot",
> -	  .offset	= 3 * SZ_1M + SZ_512K,
> -	  .size		= SZ_256K },
> -	{ .name		= "u-boot params",
> -	  .offset	= 3 * SZ_1M + SZ_512K + SZ_256K,
> -	  .size		= SZ_256K },
> -	{ .name		= "Amstrad LDR",
> -	  .offset	= 4 * SZ_1M,
> -	  .size		= SZ_256K },
> -	{ .name		= "File system",
> -	  .offset	= 4 * SZ_1M + 1 * SZ_256K,
> -	  .size		= 27 * SZ_1M },
> -	{ .name		= "PBL reserved",
> -	  .offset	= 32 * SZ_1M - 3 * SZ_256K,
> -	  .size		=  3 * SZ_256K },
> -};
> -
>  static void ams_delta_write_commit(struct ams_delta_nand *priv)
>  {
>  	gpiod_set_value(priv->gpiod_nwe, 0);
> @@ -238,6 +213,7 @@ static int ams_delta_init(struct platform_device *pdev)
>  	mtd->dev.parent = &pdev->dev;
>  
>  	nand_set_controller_data(this, priv);
> +	nand_set_flash_node(this, pdev->dev.of_node);
>  
>  	priv->gpiod_rdy = devm_gpiod_get_optional(&pdev->dev, "rdy", GPIOD_IN);
>  	if (IS_ERR(priv->gpiod_rdy)) {
> @@ -315,8 +291,7 @@ static int ams_delta_init(struct platform_device *pdev)
>  		return err;
>  
>  	/* Register the partitions */
> -	err = mtd_device_register(mtd, partition_info,
> -				  ARRAY_SIZE(partition_info));
> +	err = mtd_device_parse_register(mtd, NULL, NULL, NULL, 0);
>  	if (err)
>  		goto err_nand_cleanup;
>  
> -- 
> 2.21.0

Re: [PATCH v3] mtd: rawnand: ams-delta: Drop board specific partition info

[Janusz Krzysztofik]

Hi Ladislav,

On Thursday, April 25, 2019 12:14:28 AM CEST Ladislav Michl wrote:
> Hi Janusz,
> 
> On Wed, Apr 24, 2019 at 08:02:12PM +0200, Janusz Krzysztofik wrote:
> > After recent modifications, only a hardcoded partition info makes
> > the driver device specific.  Other than that, the driver uses GPIO
> > exclusively and can be used on any hardware.
> > 
> > Drop the partition info and use MTD partition parser with default list
> > of parser names instead.  For the OF parser to work correctly, pass
> > device of_node to mtd.
> > 
> > Amstrad Delta users should append the following partition info to their
> > kernel command line, possibly embedding it in CONFIG_CMDLINE:
> > 
> > mtdparts=ams-delta-nand:3584k(Kernel),256k(u-boot),256k(u-boot_params),\
> > 256k(Amstrad_LDR),27m(File_system),768k(PBL_reserved)
> 
> now, when driver is no longer Amstrad Delta specific, why would you want
> to have ams-delta-nand hardcoded on kernel cmdline? I'm assuming at some
> point this driver will become gpio-nand [*] or something like that and
> asking users to change their kernel cmdline twice is just unwise :)

Hmm, I have no idea of a good name for the driver if not "gpio-nand". Can you 
suggest one?
As a workaround, I can add a platform device id table to the driver with "ams-
delta-nand" as a supported device name in hope that survives possible future 
driver renaming.

> [*] btw, it is really shame gpio-nand name is already taken by driver
> living in drivers/mtd/nand/raw/gpio.c which is more likely gpio-mem-nand
> used by at least CompuLab CM-X255 and Picochip picoXcell.

I think the best approach would be to expose NAND data ports of those machines 
as GPIO ports, possibly reusing the "gpio-nand" driver code while creating a 
new GPIO driver for them if "basic-mmio-gpio" occurs inappropriate, and use 
the pure GPIO NAND driver on top.

> Otherwise your work on this driver is so amazing that I just spent
> couple of hours finding that phone and compiling some decent userspace
> for it :) Thank you!

I'm glad you like it :-)
Janusz

> 
> > For their convenience, that information is added to the board Kconfig
> > entry help text, as well as CONFIG_MTD_CMDLINE_PARTS symbol is selected
> > automatically from the board Kconfig entry if the NAND driver is also
> > selected.
> > 
> > Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
> > Cc: Tony Lindgren <tony@atomide.com>
> > Cc: Aaro Koskinen <aaro.koskinen@iki.fi>
> > ---
> > Changelog:
> > v2->v3:
> > - add information on the requirement for passing partition info via
> >   kernel command line to the board Kconfig entry help text
> > v1->v2:
> > - fix a typo poitned out by Aaro - thanks!
> > - fix device_node not passed to OF parser via mtd_info
> > - commit message reworded and reformatted a bit for better readability
> > 
> >  arch/arm/mach-omap1/Kconfig      |  7 ++++++-
> >  drivers/mtd/nand/raw/ams-delta.c | 29 ++---------------------------
> >  2 files changed, 8 insertions(+), 28 deletions(-)
> > 
> > diff --git a/arch/arm/mach-omap1/Kconfig b/arch/arm/mach-omap1/Kconfig
> > index c4694f26b5c4..41a47d251cac 100644
> > --- a/arch/arm/mach-omap1/Kconfig
> > +++ b/arch/arm/mach-omap1/Kconfig
> > @@ -164,17 +164,22 @@ config MACH_NOKIA770
> >  	  have such a device.
> >  
> >  config MACH_AMS_DELTA
> > -	bool "Amstrad E3 (Delta)"
> > +	bool "Amstrad E3 (Delta) - see help for important information"
> >  	depends on ARCH_OMAP1 && ARCH_OMAP15XX
> >  	select FIQ
> >  	select GPIO_GENERIC_PLATFORM
> >  	select LEDS_GPIO_REGISTER
> >  	select REGULATOR
> >  	select REGULATOR_FIXED_VOLTAGE
> > +	select MTD_CMDLINE_PARTS if MTD_NAND_AMS_DELTA
> >  	help
> >  	  Support for the Amstrad E3 (codename Delta) videophone. Say Y 
here
> >  	  if you have such a device.
> >  
> > +	  If you are using built-in NAND, append the following partition
> > +	  info to kernel command line:
> > +	  mtdparts=ams-delta-nand:3584k(Kernel),256k(u-boot),256k(u-
boot_params),256k(Amstrad_LDR),27m(File_system),768k(PBL_reserved)
> > +
> >  config MACH_OMAP_GENERIC
> >  	bool "Generic OMAP board"
> >  	depends on ARCH_OMAP1 && (ARCH_OMAP15XX || ARCH_OMAP16XX)
> > diff --git a/drivers/mtd/nand/raw/ams-delta.c b/drivers/mtd/nand/raw/ams-
delta.c
> > index 8312182088c1..e0f09179bbda 100644
> > --- a/drivers/mtd/nand/raw/ams-delta.c
> > +++ b/drivers/mtd/nand/raw/ams-delta.c
> > @@ -41,31 +41,6 @@ struct ams_delta_nand {
> >  	bool			data_in;
> >  };
> >  
> > -/*
> > - * Define partitions for flash devices
> > - */
> > -
> > -static const struct mtd_partition partition_info[] = {
> > -	{ .name		= "Kernel",
> > -	  .offset	= 0,
> > -	  .size		= 3 * SZ_1M + SZ_512K },
> > -	{ .name		= "u-boot",
> > -	  .offset	= 3 * SZ_1M + SZ_512K,
> > -	  .size		= SZ_256K },
> > -	{ .name		= "u-boot params",
> > -	  .offset	= 3 * SZ_1M + SZ_512K + SZ_256K,
> > -	  .size		= SZ_256K },
> > -	{ .name		= "Amstrad LDR",
> > -	  .offset	= 4 * SZ_1M,
> > -	  .size		= SZ_256K },
> > -	{ .name		= "File system",
> > -	  .offset	= 4 * SZ_1M + 1 * SZ_256K,
> > -	  .size		= 27 * SZ_1M },
> > -	{ .name		= "PBL reserved",
> > -	  .offset	= 32 * SZ_1M - 3 * SZ_256K,
> > -	  .size		=  3 * SZ_256K },
> > -};
> > -
> >  static void ams_delta_write_commit(struct ams_delta_nand *priv)
> >  {
> >  	gpiod_set_value(priv->gpiod_nwe, 0);
> > @@ -238,6 +213,7 @@ static int ams_delta_init(struct platform_device 
*pdev)
> >  	mtd->dev.parent = &pdev->dev;
> >  
> >  	nand_set_controller_data(this, priv);
> > +	nand_set_flash_node(this, pdev->dev.of_node);
> >  
> >  	priv->gpiod_rdy = devm_gpiod_get_optional(&pdev->dev, "rdy", 
GPIOD_IN);
> >  	if (IS_ERR(priv->gpiod_rdy)) {
> > @@ -315,8 +291,7 @@ static int ams_delta_init(struct platform_device 
*pdev)
> >  		return err;
> >  
> >  	/* Register the partitions */
> > -	err = mtd_device_register(mtd, partition_info,
> > -				  ARRAY_SIZE(partition_info));
> > +	err = mtd_device_parse_register(mtd, NULL, NULL, NULL, 0);
> >  	if (err)
> >  		goto err_nand_cleanup;
> >  
> 

Re: [PATCH v3] mtd: rawnand: ams-delta: Drop board specific partition info

[Ladislav Michl]

On Thu, Apr 25, 2019 at 08:42:22PM +0200, Janusz Krzysztofik wrote:
> Hi Ladislav,
> 
> On Thursday, April 25, 2019 12:14:28 AM CEST Ladislav Michl wrote:
> > Hi Janusz,
> > 
> > On Wed, Apr 24, 2019 at 08:02:12PM +0200, Janusz Krzysztofik wrote:
> > > After recent modifications, only a hardcoded partition info makes
> > > the driver device specific.  Other than that, the driver uses GPIO
> > > exclusively and can be used on any hardware.
> > > 
> > > Drop the partition info and use MTD partition parser with default list
> > > of parser names instead.  For the OF parser to work correctly, pass
> > > device of_node to mtd.
> > > 
> > > Amstrad Delta users should append the following partition info to their
> > > kernel command line, possibly embedding it in CONFIG_CMDLINE:
> > > 
> > > mtdparts=ams-delta-nand:3584k(Kernel),256k(u-boot),256k(u-boot_params),\
> > > 256k(Amstrad_LDR),27m(File_system),768k(PBL_reserved)
> > 
> > now, when driver is no longer Amstrad Delta specific, why would you want
> > to have ams-delta-nand hardcoded on kernel cmdline? I'm assuming at some
> > point this driver will become gpio-nand [*] or something like that and
> > asking users to change their kernel cmdline twice is just unwise :)
> 
> Hmm, I have no idea of a good name for the driver if not "gpio-nand". Can you 
> suggest one?

gpio-nand is so good name that it should be worth merging gpio.c and
ams-delta.c into gpio_nand.c :)

> As a workaround, I can add a platform device id table to the driver with "ams-
> delta-nand" as a supported device name in hope that survives possible future 
> driver renaming.
> 
> > [*] btw, it is really shame gpio-nand name is already taken by driver
> > living in drivers/mtd/nand/raw/gpio.c which is more likely gpio-mem-nand
> > used by at least CompuLab CM-X255 and Picochip picoXcell.
> 
> I think the best approach would be to expose NAND data ports of those machines 
> as GPIO ports, possibly reusing the "gpio-nand" driver code while creating a 
> new GPIO driver for them if "basic-mmio-gpio" occurs inappropriate, and use 
> the pure GPIO NAND driver on top.

What about adding two fields into struct ams_delta_nand holding pointers to
either ams_delta_{read,write}_buf (renamed to gpio_nand_...) or mmio r/w
functions depending on driver configuration?

> > Otherwise your work on this driver is so amazing that I just spent
> > couple of hours finding that phone and compiling some decent userspace
> > for it :) Thank you!
> 
> I'm glad you like it :-)
> Janusz

Best regards,
	ladis