[PATCH] spi: Allow using spi_bitbang_setup() with custom txrx_bufs()

[PATCH] spi: Allow using spi_bitbang_setup() with custom txrx_bufs()

[Magnus Damm]

From: Magnus Damm <damm@opensource.se>

This patch modifies the shared spi bitbanging code
to allow using spi_bitbang_setup() even though the
txrx_word[] callbacks are unset. Useful for drivers
that want to make use of spi_bitbang_setup() but
have their own txrx_bufs() callback.

While at it, drop the MSIOF driver workaround.

Signed-off-by: Magnus Damm <damm@opensource.se>
---

 Depends on the MSIOF driver.

 drivers/spi/spi_bitbang.c  |   25 ++++++++++++++-----------
 drivers/spi/spi_sh_msiof.c |   11 -----------
 2 files changed, 14 insertions(+), 22 deletions(-)

--- 0001/drivers/spi/spi_bitbang.c
+++ work/drivers/spi/spi_bitbang.c	2009-11-25 15:30:45.000000000 +0900
@@ -176,6 +176,14 @@ int spi_bitbang_setup_transfer(struct sp
 }
 EXPORT_SYMBOL_GPL(spi_bitbang_setup_transfer);
 
+static int spi_bitbang_bufs(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct spi_bitbang_cs	*cs = spi->controller_state;
+	unsigned		nsecs = cs->nsecs;
+
+	return cs->txrx_bufs(spi, cs->txrx_word, nsecs, t);
+}
+
 /**
  * spi_bitbang_setup - default setup for per-word I/O loops
  */
@@ -183,6 +191,7 @@ int spi_bitbang_setup(struct spi_device 
 {
 	struct spi_bitbang_cs	*cs = spi->controller_state;
 	struct spi_bitbang	*bitbang;
+	int			mode_mask = SPI_CPOL | SPI_CPHA;
 	int			retval;
 	unsigned long		flags;
 
@@ -196,9 +205,11 @@ int spi_bitbang_setup(struct spi_device 
 	}
 
 	/* per-word shift register access, in hardware or bitbanging */
-	cs->txrx_word = bitbang->txrx_word[spi->mode & (SPI_CPOL|SPI_CPHA)];
-	if (!cs->txrx_word)
-		return -EINVAL;
+	if (bitbang->txrx_bufs == spi_bitbang_bufs) {
+		cs->txrx_word = bitbang->txrx_word[spi->mode & mode_mask];
+		if (!cs->txrx_word)
+			return -EINVAL;
+	}
 
 	retval = bitbang->setup_transfer(spi, NULL);
 	if (retval < 0)
@@ -232,14 +243,6 @@ void spi_bitbang_cleanup(struct spi_devi
 }
 EXPORT_SYMBOL_GPL(spi_bitbang_cleanup);
 
-static int spi_bitbang_bufs(struct spi_device *spi, struct spi_transfer *t)
-{
-	struct spi_bitbang_cs	*cs = spi->controller_state;
-	unsigned		nsecs = cs->nsecs;
-
-	return cs->txrx_bufs(spi, cs->txrx_word, nsecs, t);
-}
-
 /*----------------------------------------------------------------------*/
 
 /*
--- 0002/drivers/spi/spi_sh_msiof.c
+++ work/drivers/spi/spi_sh_msiof.c	2009-11-25 15:25:32.000000000 +0900
@@ -510,13 +510,6 @@ static int sh_msiof_spi_txrx(struct spi_
 	return bytes_done;
 }
 
-static u32 sh_msiof_spi_txrx_word(struct spi_device *spi, unsigned nsecs,
-				  u32 word, u8 bits)
-{
-	BUG_ON(1); /* unused but needed by bitbang code */
-	return 0;
-}
-
 static int sh_msiof_spi_probe(struct platform_device *pdev)
 {
 	struct resource	*r;
@@ -594,10 +587,6 @@ static int sh_msiof_spi_probe(struct pla
 	p->bitbang.chipselect = sh_msiof_spi_chipselect;
 	p->bitbang.setup_transfer = sh_msiof_spi_setup_transfer;
 	p->bitbang.txrx_bufs = sh_msiof_spi_txrx;
-	p->bitbang.txrx_word[SPI_MODE_0] = sh_msiof_spi_txrx_word;
-	p->bitbang.txrx_word[SPI_MODE_1] = sh_msiof_spi_txrx_word;
-	p->bitbang.txrx_word[SPI_MODE_2] = sh_msiof_spi_txrx_word;
-	p->bitbang.txrx_word[SPI_MODE_3] = sh_msiof_spi_txrx_word;
 
 	ret = spi_bitbang_start(&p->bitbang);
 	if (ret == 0)

Re: [PATCH] spi: Allow using spi_bitbang_setup() with custom txrx_bufs()

[Grant Likely]

On Wed, Nov 25, 2009 at 1:26 AM, Magnus Damm <magnus.damm@gmail.com> wrote:
> From: Magnus Damm <damm@opensource.se>
>
> This patch modifies the shared spi bitbanging code
> to allow using spi_bitbang_setup() even though the
> txrx_word[] callbacks are unset. Useful for drivers
> that want to make use of spi_bitbang_setup() but
> have their own txrx_bufs() callback.
>
> While at it, drop the MSIOF driver workaround.
>
> Signed-off-by: Magnus Damm <damm@opensource.se>
> ---
>
>  Depends on the MSIOF driver.
>
>  drivers/spi/spi_bitbang.c  |   25 ++++++++++++++-----------
>  drivers/spi/spi_sh_msiof.c |   11 -----------
>  2 files changed, 14 insertions(+), 22 deletions(-)
>
> --- 0001/drivers/spi/spi_bitbang.c
> +++ work/drivers/spi/spi_bitbang.c      2009-11-25 15:30:45.000000000 +0900
> @@ -176,6 +176,14 @@ int spi_bitbang_setup_transfer(struct sp
>  }
>  EXPORT_SYMBOL_GPL(spi_bitbang_setup_transfer);
>
> +static int spi_bitbang_bufs(struct spi_device *spi, struct spi_transfer *t)
> +{
> +       struct spi_bitbang_cs   *cs = spi->controller_state;
> +       unsigned                nsecs = cs->nsecs;
> +
> +       return cs->txrx_bufs(spi, cs->txrx_word, nsecs, t);
> +}
> +
>  /**
>  * spi_bitbang_setup - default setup for per-word I/O loops
>  */
> @@ -183,6 +191,7 @@ int spi_bitbang_setup(struct spi_device
>  {
>        struct spi_bitbang_cs   *cs = spi->controller_state;
>        struct spi_bitbang      *bitbang;
> +       int                     mode_mask = SPI_CPOL | SPI_CPHA;
>        int                     retval;
>        unsigned long           flags;
>
> @@ -196,9 +205,11 @@ int spi_bitbang_setup(struct spi_device
>        }
>
>        /* per-word shift register access, in hardware or bitbanging */
> -       cs->txrx_word = bitbang->txrx_word[spi->mode & (SPI_CPOL|SPI_CPHA)];
> -       if (!cs->txrx_word)
> -               return -EINVAL;
> +       if (bitbang->txrx_bufs == spi_bitbang_bufs) {
> +               cs->txrx_word = bitbang->txrx_word[spi->mode & mode_mask];
> +               if (!cs->txrx_word)
> +                       return -EINVAL;
> +       }

Hmmm... this smells like an ugly hack to me.  It seems to me that if
some bitbang backend drivers don't want this code, then it should be
encoded into a callback so it can be overridden.  Thoughts.

g.

-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.

Re: [PATCH] spi: Allow using spi_bitbang_setup() with custom txrx_bufs()

[Magnus Damm]

[-- Attachment #1: Type: text/plain, Size: 1761 bytes --]

Hi Grant,

On Thu, Nov 26, 2009 at 7:15 AM, Grant Likely <grant.likely@secretlab.ca> wrote:
> On Wed, Nov 25, 2009 at 1:26 AM, Magnus Damm <magnus.damm@gmail.com> wrote:
>> This patch modifies the shared spi bitbanging code
>> to allow using spi_bitbang_setup() even though the
>> txrx_word[] callbacks are unset. Useful for drivers
>> that want to make use of spi_bitbang_setup() but
>> have their own txrx_bufs() callback.

>> @@ -196,9 +205,11 @@ int spi_bitbang_setup(struct spi_device
>>        }
>>
>>        /* per-word shift register access, in hardware or bitbanging */
>> -       cs->txrx_word = bitbang->txrx_word[spi->mode & (SPI_CPOL|SPI_CPHA)];
>> -       if (!cs->txrx_word)
>> -               return -EINVAL;
>> +       if (bitbang->txrx_bufs == spi_bitbang_bufs) {
>> +               cs->txrx_word = bitbang->txrx_word[spi->mode & mode_mask];
>> +               if (!cs->txrx_word)
>> +                       return -EINVAL;
>> +       }
>
> Hmmm... this smells like an ugly hack to me.  It seems to me that if
> some bitbang backend drivers don't want this code, then it should be
> encoded into a callback so it can be overridden.  Thoughts.

Yeah, it's far from clean. I want to make use of spi_bitbang_setup()
in my MSIOF driver, but I want to avoid dummy txtx_word[] callbacks
that will be unused since i'm using a driver specific
bitbang->txrx_bufs function.

I guess the attached patch is slightly cleaner? I like the idea of
letting bitbang drivers use shared code for
spi_bitbang_setup()/spi_bitbang_cleanup() with their private
setup_transfer() function which in turn calls
spi_bitbang_setup_transfer(). My impression is that there's quite a
bit of duplicated setup()/cleanup() code.

/ magnus

[-- Attachment #2: linux-2.6.33-pre-spi-word-mode-setup-20091126.patch --]
[-- Type: application/octet-stream, Size: 3503 bytes --]

From: Magnus Damm <damm@opensource.se>

Signed-off-by: Magnus Damm <damm@opensource.se>
---

 drivers/spi/spi_bitbang.c       |   37 ++++++++++++++++++++++++++++++-------
 drivers/spi/spi_gpio.c          |    2 +-
 include/linux/spi/spi_bitbang.h |    1 +
 3 files changed, 32 insertions(+), 8 deletions(-)

--- 0001/drivers/spi/spi_bitbang.c
+++ work/drivers/spi/spi_bitbang.c	2009-11-26 14:59:53.000000000 +0900
@@ -177,7 +177,7 @@ int spi_bitbang_setup_transfer(struct sp
 EXPORT_SYMBOL_GPL(spi_bitbang_setup_transfer);
 
 /**
- * spi_bitbang_setup - default setup for per-word I/O loops
+ * spi_bitbang_setup - setup function when bitbang->txrx_word[] are unused
  */
 int spi_bitbang_setup(struct spi_device *spi)
 {
@@ -195,11 +195,6 @@ int spi_bitbang_setup(struct spi_device 
 		spi->controller_state = cs;
 	}
 
-	/* per-word shift register access, in hardware or bitbanging */
-	cs->txrx_word = bitbang->txrx_word[spi->mode & (SPI_CPOL|SPI_CPHA)];
-	if (!cs->txrx_word)
-		return -EINVAL;
-
 	retval = bitbang->setup_transfer(spi, NULL);
 	if (retval < 0)
 		return retval;
@@ -224,6 +219,32 @@ int spi_bitbang_setup(struct spi_device 
 EXPORT_SYMBOL_GPL(spi_bitbang_setup);
 
 /**
+ * spi_bitbang_setup_word_mode - default setup for per-word I/O loops
+ */
+int spi_bitbang_setup_word_mode(struct spi_device *spi)
+{
+	struct spi_bitbang_cs	*cs;
+	struct spi_bitbang	*bitbang;
+	void			*txrx_word;
+	int			retval;
+
+	bitbang = spi_master_get_devdata(spi->master);
+
+	/* per-word shift register access, in hardware or bitbanging */
+	txrx_word = bitbang->txrx_word[spi->mode & (SPI_CPOL | SPI_CPHA)];
+	if (!txrx_word)
+		return -EINVAL;
+
+	retval = spi_bitbang_setup(spi);
+	if (!retval) {
+		cs = spi->controller_state;
+		cs->txrx_word = txrx_word;
+	}
+	return retval;
+}
+EXPORT_SYMBOL_GPL(spi_bitbang_setup_word_mode);
+
+/**
  * spi_bitbang_cleanup - default cleanup for per-word I/O loops
  */
 void spi_bitbang_cleanup(struct spi_device *spi)
@@ -455,6 +476,8 @@ int spi_bitbang_start(struct spi_bitbang
 
 	if (!bitbang->master->transfer)
 		bitbang->master->transfer = spi_bitbang_transfer;
+
+	/* "word mode" when spi_bitbang_bufs() are used */
 	if (!bitbang->txrx_bufs) {
 		bitbang->use_dma = 0;
 		bitbang->txrx_bufs = spi_bitbang_bufs;
@@ -462,7 +485,7 @@ int spi_bitbang_start(struct spi_bitbang
 			if (!bitbang->setup_transfer)
 				bitbang->setup_transfer =
 					 spi_bitbang_setup_transfer;
-			bitbang->master->setup = spi_bitbang_setup;
+			bitbang->master->setup = spi_bitbang_setup_word_mode;
 			bitbang->master->cleanup = spi_bitbang_cleanup;
 		}
 	} else if (!bitbang->master->setup)
--- 0001/drivers/spi/spi_gpio.c
+++ work/drivers/spi/spi_gpio.c	2009-11-26 14:53:37.000000000 +0900
@@ -201,7 +201,7 @@ static int spi_gpio_setup(struct spi_dev
 		}
 	}
 	if (!status)
-		status = spi_bitbang_setup(spi);
+		status = spi_bitbang_setup_word_mode(spi);
 	if (status) {
 		if (!spi->controller_state && cs != SPI_GPIO_NO_CHIPSELECT)
 			gpio_free(cs);
--- 0001/include/linux/spi/spi_bitbang.h
+++ work/include/linux/spi/spi_bitbang.h	2009-11-26 14:54:08.000000000 +0900
@@ -58,6 +58,7 @@ struct spi_bitbang {
  * methods, if you like.
  */
 extern int spi_bitbang_setup(struct spi_device *spi);
+extern int spi_bitbang_setup_word_mode(struct spi_device *spi);
 extern void spi_bitbang_cleanup(struct spi_device *spi);
 extern int spi_bitbang_transfer(struct spi_device *spi, struct spi_message *m);
 extern int spi_bitbang_setup_transfer(struct spi_device *spi,

Re: [PATCH] spi: Allow using spi_bitbang_setup() with custom txrx_bufs()

[Grant Likely]

On Wed, Nov 25, 2009 at 11:47 PM, Magnus Damm <magnus.damm@gmail.com> wrote:
> Hi Grant,
>
> On Thu, Nov 26, 2009 at 7:15 AM, Grant Likely <grant.likely@secretlab.ca> wrote:
>> On Wed, Nov 25, 2009 at 1:26 AM, Magnus Damm <magnus.damm@gmail.com> wrote:
>>>        /* per-word shift register access, in hardware or bitbanging */
>>> -       cs->txrx_word = bitbang->txrx_word[spi->mode & (SPI_CPOL|SPI_CPHA)];
>>> -       if (!cs->txrx_word)
>>> -               return -EINVAL;
>>> +       if (bitbang->txrx_bufs == spi_bitbang_bufs) {
>>> +               cs->txrx_word = bitbang->txrx_word[spi->mode & mode_mask];
>>> +               if (!cs->txrx_word)
>>> +                       return -EINVAL;
>>> +       }
>>
>> Hmmm... this smells like an ugly hack to me.  It seems to me that if
>> some bitbang backend drivers don't want this code, then it should be
>> encoded into a callback so it can be overridden.  Thoughts.
>
> Yeah, it's far from clean. I want to make use of spi_bitbang_setup()
> in my MSIOF driver, but I want to avoid dummy txtx_word[] callbacks
> that will be unused since i'm using a driver specific
> bitbang->txrx_bufs function.
>
> I guess the attached patch is slightly cleaner? I like the idea of
> letting bitbang drivers use shared code for
> spi_bitbang_setup()/spi_bitbang_cleanup() with their private
> setup_transfer() function which in turn calls
> spi_bitbang_setup_transfer(). My impression is that there's quite a
> bit of duplicated setup()/cleanup() code.

This is certainly less ugly.  But with the points brought up in the
other thread, I want to have a close look at spi-bitbang before I
start applying stuff.  It seems nasty.  Give me a few days.

g.

-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.

Re: [PATCH] spi: Allow using spi_bitbang_setup() with custom txrx_bufs()

[Magnus Damm]

On Thu, Nov 26, 2009 at 4:21 PM, Grant Likely <grant.likely@secretlab.ca> wrote:
> On Wed, Nov 25, 2009 at 11:47 PM, Magnus Damm <magnus.damm@gmail.com> wrote:
>> On Thu, Nov 26, 2009 at 7:15 AM, Grant Likely <grant.likely@secretlab.ca> wrote:
>>> On Wed, Nov 25, 2009 at 1:26 AM, Magnus Damm <magnus.damm@gmail.com> wrote:
>>>>        /* per-word shift register access, in hardware or bitbanging */
>>>> -       cs->txrx_word = bitbang->txrx_word[spi->mode & (SPI_CPOL|SPI_CPHA)];
>>>> -       if (!cs->txrx_word)
>>>> -               return -EINVAL;
>>>> +       if (bitbang->txrx_bufs == spi_bitbang_bufs) {
>>>> +               cs->txrx_word = bitbang->txrx_word[spi->mode & mode_mask];
>>>> +               if (!cs->txrx_word)
>>>> +                       return -EINVAL;
>>>> +       }
>>>
>>> Hmmm... this smells like an ugly hack to me.  It seems to me that if
>>> some bitbang backend drivers don't want this code, then it should be
>>> encoded into a callback so it can be overridden.  Thoughts.
>>
>> Yeah, it's far from clean. I want to make use of spi_bitbang_setup()
>> in my MSIOF driver, but I want to avoid dummy txtx_word[] callbacks
>> that will be unused since i'm using a driver specific
>> bitbang->txrx_bufs function.
>>
>> I guess the attached patch is slightly cleaner? I like the idea of
>> letting bitbang drivers use shared code for
>> spi_bitbang_setup()/spi_bitbang_cleanup() with their private
>> setup_transfer() function which in turn calls
>> spi_bitbang_setup_transfer(). My impression is that there's quite a
>> bit of duplicated setup()/cleanup() code.
>
> This is certainly less ugly.  But with the points brought up in the
> other thread, I want to have a close look at spi-bitbang before I
> start applying stuff.  It seems nasty.  Give me a few days.

Sure, I plan on posting a V2 of the MSIOF driver. I plan to keep the
dummy txrx_word() function for now - this to disconnect the cleanup
from the driver integration, hope that sounds like a good plan.

Cheers,

/ magnus

Re: [PATCH] spi: Allow using spi_bitbang_setup() with custom txrx_bufs()

[Grant Likely]

On Thu, Nov 26, 2009 at 12:50 AM, Magnus Damm <magnus.damm@gmail.com> wrote:
> On Thu, Nov 26, 2009 at 4:21 PM, Grant Likely <grant.likely@secretlab.ca> wrote:
>> On Wed, Nov 25, 2009 at 11:47 PM, Magnus Damm <magnus.damm@gmail.com> wrote:
>>> On Thu, Nov 26, 2009 at 7:15 AM, Grant Likely <grant.likely@secretlab.ca> wrote:
>>>> On Wed, Nov 25, 2009 at 1:26 AM, Magnus Damm <magnus.damm@gmail.com> wrote:
>>>>>        /* per-word shift register access, in hardware or bitbanging */
>>>>> -       cs->txrx_word = bitbang->txrx_word[spi->mode & (SPI_CPOL|SPI_CPHA)];
>>>>> -       if (!cs->txrx_word)
>>>>> -               return -EINVAL;
>>>>> +       if (bitbang->txrx_bufs == spi_bitbang_bufs) {
>>>>> +               cs->txrx_word = bitbang->txrx_word[spi->mode & mode_mask];
>>>>> +               if (!cs->txrx_word)
>>>>> +                       return -EINVAL;
>>>>> +       }
>>>>
>>>> Hmmm... this smells like an ugly hack to me.  It seems to me that if
>>>> some bitbang backend drivers don't want this code, then it should be
>>>> encoded into a callback so it can be overridden.  Thoughts.
>>>
>>> Yeah, it's far from clean. I want to make use of spi_bitbang_setup()
>>> in my MSIOF driver, but I want to avoid dummy txtx_word[] callbacks
>>> that will be unused since i'm using a driver specific
>>> bitbang->txrx_bufs function.
>>>
>>> I guess the attached patch is slightly cleaner? I like the idea of
>>> letting bitbang drivers use shared code for
>>> spi_bitbang_setup()/spi_bitbang_cleanup() with their private
>>> setup_transfer() function which in turn calls
>>> spi_bitbang_setup_transfer(). My impression is that there's quite a
>>> bit of duplicated setup()/cleanup() code.
>>
>> This is certainly less ugly.  But with the points brought up in the
>> other thread, I want to have a close look at spi-bitbang before I
>> start applying stuff.  It seems nasty.  Give me a few days.
>
> Sure, I plan on posting a V2 of the MSIOF driver. I plan to keep the
> dummy txrx_word() function for now - this to disconnect the cleanup
> from the driver integration, hope that sounds like a good plan.

Works for me.  Now I just need to find someone with the time to
refactor spi-bitbang.  :-)

g.




-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.