[PATCH v2 0/6] mfd: trivial demodularization of non-modular drivers.

[PATCH v2 0/6] mfd: trivial demodularization of non-modular drivers.

[Paul Gortmaker]

I grouped this little series of mfd commits together because of the
common theme of their relatively trivial use of modular infrastructure
in these non-modular drivers.

What that means is there are no orphaned __exit functions to remove;
no unused ".remove" functions linked into the driver struct to be
deleted -- so in the end we have binary equivalence between the
pre-patched code and the post-patched code. Easy to review and low risk.

More specifically - the only thing we are doing here is mapping the
initcall that binds in the driver from the module variant to the
built-in variant ; something that CPP would do for us anyway -- and
then throwing away any MODULE_ tags which are no-ops in non-modular
builds (while preserving any author/desc. info they had in comments).
And in doing that, we can toss the include of module.h in favour of
init.h (asssuming it wasn't included already).

One exception is patch #2; it converts a driver from bool to tristate,
as was asked per the v1 review[1].  This has been build tested, but
I don't have the specific hardware for run time testing.

For anyone new to the underlying goal of this cleanup, we are trying to
make driver code consistent with the Makefiles/Kconfigs that control them.

This means not using modular functions/macros for drivers that can never
be built as a module.  Some of the other downfalls this leads to are:

 (1) it is easy to accidentally write unused module_exit and remove code
 (2) it can be misleading when reading the source, thinking it can be
     modular when the Makefile and/or Kconfig prohibit it
 (3) it requires the include of the module.h header file which in turn
     includes nearly everything else, thus adding to CPP overhead.
 (4) it gets copied/replicated into other drivers and spreads like weeds.

Build tested on linux-next for arm, arm64 and x86-64 to ensure no typos
or similar issues crept in.

[1] https://lkml.kernel.org/r/20160705012544.14143-1-paul.gortmaker@windriver.com

Paul.
---

[v1 --> v2: make one driver tristate, add some Ackd-by tags.]

Cc: Boris BREZILLON <boris.brezillon@free-electrons.com>
Cc: Florian Lobmaier <florian.lobmaier@ams.com>
Cc: Laxman Dewangan <ldewangan@nvidia.com>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Samuel Ortiz <sameo@linux.intel.com>
Cc: Sourav Poddar <sourav.poddar@ti.com>
Cc: Thor Thayer <tthayer@opensource.altera.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: linux-omap@vger.kernel.org

Paul Gortmaker (6):
  mfd: altera-a10sr: make it explicitly non-modular
  mfd: as3722: convert MFD_AS3722 from bool to tristate
  mfd: intel_msic: Make it explicitly non-modular
  mfd: smsc-ece1099: Make it explicitly non-modular
  mfd: sun6i-prcm: Make it explicitly non-modular
  mfd: twl-core: Make it explicitly non-modular

 drivers/mfd/Kconfig        |  2 +-
 drivers/mfd/altera-a10sr.c | 14 ++++++--------
 drivers/mfd/intel_msic.c   |  9 ++-------
 drivers/mfd/smsc-ece1099.c | 11 ++---------
 drivers/mfd/sun6i-prcm.c   |  8 ++------
 drivers/mfd/twl-core.c     |  9 +--------
 6 files changed, 14 insertions(+), 39 deletions(-)

-- 
2.8.4

[PATCH 6/6] mfd: twl-core: Make it explicitly non-modular

[Paul Gortmaker]

The Kconfig currently controlling compilation of this code is:

drivers/mfd/Kconfig:config TWL4030_CORE
drivers/mfd/Kconfig:    bool "TI TWL4030/TWL5030/TWL6030/TPS659x0 Support"

...meaning that it currently is not being built as a module by anyone.

Lets remove what modular code that we can, so that when reading the
driver there is less doubt that it is builtin-only.  Note that we can't
remove the twl_remove() itself ; it is still used by the probe unwind
routine.  So we leave it linked into the .remove as well, even though
it will most likely never be called via that path from an unbind.

Since module_i2c_driver() uses the same init level priority as
builtin_i2c_driver() the init ordering remains unchanged with
this commit.

Also note that MODULE_DEVICE_TABLE is a no-op for non-modular code.

We also delete the MODULE_LICENSE tag etc. since all that information
is already contained at the top of the file in the comments.

Cc: Tony Lindgren <tony@atomide.com>
Cc: Samuel Ortiz <sameo@linux.intel.com>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: linux-omap@vger.kernel.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
 drivers/mfd/twl-core.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/drivers/mfd/twl-core.c b/drivers/mfd/twl-core.c
index a49d3db6d936..c64615dca2bd 100644
--- a/drivers/mfd/twl-core.c
+++ b/drivers/mfd/twl-core.c
@@ -30,7 +30,6 @@
 
 #include <linux/init.h>
 #include <linux/mutex.h>
-#include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
 #include <linux/clk.h>
@@ -1258,7 +1257,6 @@ static const struct i2c_device_id twl_ids[] = {
 	{ "twl6032", TWL6030_CLASS | TWL6032_SUBCLASS }, /* "Phoenix lite" */
 	{ /* end of list */ },
 };
-MODULE_DEVICE_TABLE(i2c, twl_ids);
 
 /* One Client Driver , 4 Clients */
 static struct i2c_driver twl_driver = {
@@ -1267,9 +1265,4 @@ static struct i2c_driver twl_driver = {
 	.probe		= twl_probe,
 	.remove		= twl_remove,
 };
-
-module_i2c_driver(twl_driver);
-
-MODULE_AUTHOR("Texas Instruments, Inc.");
-MODULE_DESCRIPTION("I2C Core interface for TWL");
-MODULE_LICENSE("GPL");
+builtin_i2c_driver(twl_driver);
-- 
2.8.4

Re: [PATCH 6/6] mfd: twl-core: Make it explicitly non-modular

[Tony Lindgren]

* Paul Gortmaker <paul.gortmaker@windriver.com> [160912 07:41]:
> The Kconfig currently controlling compilation of this code is:
> 
> drivers/mfd/Kconfig:config TWL4030_CORE
> drivers/mfd/Kconfig:    bool "TI TWL4030/TWL5030/TWL6030/TPS659x0 Support"
> 
> ...meaning that it currently is not being built as a module by anyone.
> 
> Lets remove what modular code that we can, so that when reading the
> driver there is less doubt that it is builtin-only.  Note that we can't
> remove the twl_remove() itself ; it is still used by the probe unwind
> routine.  So we leave it linked into the .remove as well, even though
> it will most likely never be called via that path from an unbind.
> 
> Since module_i2c_driver() uses the same init level priority as
> builtin_i2c_driver() the init ordering remains unchanged with
> this commit.
> 
> Also note that MODULE_DEVICE_TABLE is a no-op for non-modular code.
> 
> We also delete the MODULE_LICENSE tag etc. since all that information
> is already contained at the top of the file in the comments.
> 
> Cc: Tony Lindgren <tony@atomide.com>
> Cc: Samuel Ortiz <sameo@linux.intel.com>
> Cc: Lee Jones <lee.jones@linaro.org>
> Cc: linux-omap@vger.kernel.org
> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

Yeah makes sense to me:

Acked-by: Tony Lindgren <tony@atomide.com>

Re: [PATCH 6/6] mfd: twl-core: Make it explicitly non-modular

[Lee Jones]

On Mon, 12 Sep 2016, Paul Gortmaker wrote:

> The Kconfig currently controlling compilation of this code is:
> 
> drivers/mfd/Kconfig:config TWL4030_CORE
> drivers/mfd/Kconfig:    bool "TI TWL4030/TWL5030/TWL6030/TPS659x0 Support"
> 
> ...meaning that it currently is not being built as a module by anyone.
> 
> Lets remove what modular code that we can, so that when reading the
> driver there is less doubt that it is builtin-only.  Note that we can't
> remove the twl_remove() itself ; it is still used by the probe unwind
> routine.  So we leave it linked into the .remove as well, even though
> it will most likely never be called via that path from an unbind.
> 
> Since module_i2c_driver() uses the same init level priority as
> builtin_i2c_driver() the init ordering remains unchanged with
> this commit.
> 
> Also note that MODULE_DEVICE_TABLE is a no-op for non-modular code.
> 
> We also delete the MODULE_LICENSE tag etc. since all that information
> is already contained at the top of the file in the comments.
> 
> Cc: Tony Lindgren <tony@atomide.com>
> Cc: Samuel Ortiz <sameo@linux.intel.com>
> Cc: Lee Jones <lee.jones@linaro.org>
> Cc: linux-omap@vger.kernel.org
> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
> ---
>  drivers/mfd/twl-core.c | 9 +--------
>  1 file changed, 1 insertion(+), 8 deletions(-)

Applied, thanks.

> diff --git a/drivers/mfd/twl-core.c b/drivers/mfd/twl-core.c
> index a49d3db6d936..c64615dca2bd 100644
> --- a/drivers/mfd/twl-core.c
> +++ b/drivers/mfd/twl-core.c
> @@ -30,7 +30,6 @@
>  
>  #include <linux/init.h>
>  #include <linux/mutex.h>
> -#include <linux/module.h>
>  #include <linux/platform_device.h>
>  #include <linux/regmap.h>
>  #include <linux/clk.h>
> @@ -1258,7 +1257,6 @@ static const struct i2c_device_id twl_ids[] = {
>  	{ "twl6032", TWL6030_CLASS | TWL6032_SUBCLASS }, /* "Phoenix lite" */
>  	{ /* end of list */ },
>  };
> -MODULE_DEVICE_TABLE(i2c, twl_ids);
>  
>  /* One Client Driver , 4 Clients */
>  static struct i2c_driver twl_driver = {
> @@ -1267,9 +1265,4 @@ static struct i2c_driver twl_driver = {
>  	.probe		= twl_probe,
>  	.remove		= twl_remove,
>  };
> -
> -module_i2c_driver(twl_driver);
> -
> -MODULE_AUTHOR("Texas Instruments, Inc.");
> -MODULE_DESCRIPTION("I2C Core interface for TWL");
> -MODULE_LICENSE("GPL");
> +builtin_i2c_driver(twl_driver);

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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