Re: [PATCH v2 1/5] spi: introduce mmap read support for spi flash devices

[Mark Brown]

On Thu, Nov 05, 2015 at 05:59:36PM +0530, Vignesh R wrote:
> On 11/04/2015 08:09 PM, Mark Brown wrote:

> > It's a bit worrying that this doesn't sync with the message queue except
> > via the mutex: this means that we might be out of order with respect to
> > any asynchronous transfers that are happening on the device.  I'm not
> > sure that this is a practical problem, though there is some risk of
> > unfair scheduling that would have to be under extreme load and it might
> > make sense to prioritise reads anyway.

> Since mmap interface is used only by mtd flash drivers and since almost
> all mtd flash devices use synchronous transfers (spi_sync()), IMO, there
> wont be out of order problem wrt mtd flashes.
> But mmap read might delay transfers queued for non mtd flash devices. It
> is difficult to wait for all transfers already queued to be pumped out
> by __spi_pump_messages() and then do the mmap transfer. Do you have any
> thoughts on how to sync with message queue?

Like I say I think it probably doesn't matter.  The main issue would be
with other devices sharing the bus with a flash chip.


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Re: [PATCH v2 1/5] spi: introduce mmap read support for spi flash devices

[Vignesh R]

On 11/04/2015 08:09 PM, Mark Brown wrote:
> On Tue, Nov 03, 2015 at 03:36:10PM +0530, Vignesh R wrote:
> 
>> +}
>> +mutex_lock(>mmap_lock_mutex);
>> +ret = master->spi_mtd_mmap_read(spi, from, len, retlen, buf,
>> +read_opcode, addr_width,
>> +dummy_bytes);
>> +mutex_unlock(>mmap_lock_mutex);
>> +if (master->auto_runtime_pm)
>> +pm_runtime_put(master->dev.parent);
> 
> It's a bit worrying that this doesn't sync with the message queue except
> via the mutex: this means that we might be out of order with respect to
> any asynchronous transfers that are happening on the device.  I'm not
> sure that this is a practical problem, though there is some risk of
> unfair scheduling that would have to be under extreme load and it might
> make sense to prioritise reads anyway.
> 

Since mmap interface is used only by mtd flash drivers and since almost
all mtd flash devices use synchronous transfers (spi_sync()), IMO, there
wont be out of order problem wrt mtd flashes.
But mmap read might delay transfers queued for non mtd flash devices. It
is difficult to wait for all transfers already queued to be pumped out
by __spi_pump_messages() and then do the mmap transfer. Do you have any
thoughts on how to sync with message queue?

-- 
Regards
Vignesh
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Re: [PATCH v2 1/5] spi: introduce mmap read support for spi flash devices

[Vignesh R]

On 11/04/2015 08:09 PM, Mark Brown wrote:
> On Tue, Nov 03, 2015 at 03:36:10PM +0530, Vignesh R wrote:
> 
>> +}
>> +mutex_lock(>mmap_lock_mutex);
>> +ret = master->spi_mtd_mmap_read(spi, from, len, retlen, buf,
>> +read_opcode, addr_width,
>> +dummy_bytes);
>> +mutex_unlock(>mmap_lock_mutex);
>> +if (master->auto_runtime_pm)
>> +pm_runtime_put(master->dev.parent);
> 
> It's a bit worrying that this doesn't sync with the message queue except
> via the mutex: this means that we might be out of order with respect to
> any asynchronous transfers that are happening on the device.  I'm not
> sure that this is a practical problem, though there is some risk of
> unfair scheduling that would have to be under extreme load and it might
> make sense to prioritise reads anyway.
> 

Since mmap interface is used only by mtd flash drivers and since almost
all mtd flash devices use synchronous transfers (spi_sync()), IMO, there
wont be out of order problem wrt mtd flashes.
But mmap read might delay transfers queued for non mtd flash devices. It
is difficult to wait for all transfers already queued to be pumped out
by __spi_pump_messages() and then do the mmap transfer. Do you have any
thoughts on how to sync with message queue?

-- 
Regards
Vignesh
--
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Re: [PATCH v2 1/5] spi: introduce mmap read support for spi flash devices

[Mark Brown]

On Thu, Nov 05, 2015 at 05:59:36PM +0530, Vignesh R wrote:
> On 11/04/2015 08:09 PM, Mark Brown wrote:

> > It's a bit worrying that this doesn't sync with the message queue except
> > via the mutex: this means that we might be out of order with respect to
> > any asynchronous transfers that are happening on the device.  I'm not
> > sure that this is a practical problem, though there is some risk of
> > unfair scheduling that would have to be under extreme load and it might
> > make sense to prioritise reads anyway.

> Since mmap interface is used only by mtd flash drivers and since almost
> all mtd flash devices use synchronous transfers (spi_sync()), IMO, there
> wont be out of order problem wrt mtd flashes.
> But mmap read might delay transfers queued for non mtd flash devices. It
> is difficult to wait for all transfers already queued to be pumped out
> by __spi_pump_messages() and then do the mmap transfer. Do you have any
> thoughts on how to sync with message queue?

Like I say I think it probably doesn't matter.  The main issue would be
with other devices sharing the bus with a flash chip.


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Re: [PATCH v2 1/5] spi: introduce mmap read support for spi flash devices

[Mark Brown]

On Tue, Nov 03, 2015 at 03:36:10PM +0530, Vignesh R wrote:

> + }
> + mutex_lock(>mmap_lock_mutex);
> + ret = master->spi_mtd_mmap_read(spi, from, len, retlen, buf,
> + read_opcode, addr_width,
> + dummy_bytes);
> + mutex_unlock(>mmap_lock_mutex);
> + if (master->auto_runtime_pm)
> + pm_runtime_put(master->dev.parent);

It's a bit worrying that this doesn't sync with the message queue except
via the mutex: this means that we might be out of order with respect to
any asynchronous transfers that are happening on the device.  I'm not
sure that this is a practical problem, though there is some risk of
unfair scheduling that would have to be under extreme load and it might
make sense to prioritise reads anyway.


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Re: [PATCH v2 1/5] spi: introduce mmap read support for spi flash devices

[Mark Brown]

On Tue, Nov 03, 2015 at 03:36:10PM +0530, Vignesh R wrote:

> + }
> + mutex_lock(>mmap_lock_mutex);
> + ret = master->spi_mtd_mmap_read(spi, from, len, retlen, buf,
> + read_opcode, addr_width,
> + dummy_bytes);
> + mutex_unlock(>mmap_lock_mutex);
> + if (master->auto_runtime_pm)
> + pm_runtime_put(master->dev.parent);

It's a bit worrying that this doesn't sync with the message queue except
via the mutex: this means that we might be out of order with respect to
any asynchronous transfers that are happening on the device.  I'm not
sure that this is a practical problem, though there is some risk of
unfair scheduling that would have to be under extreme load and it might
make sense to prioritise reads anyway.


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Re: [PATCH v2 1/5] spi: introduce mmap read support for spi flash devices

[Vignesh R]

Hi,

On 11/03/2015 04:49 PM, Michal Suchanek wrote:
> On 3 November 2015 at 11:06, Vignesh R  wrote:
>> In addition to providing direct access to SPI bus, some spi controller
>> hardwares (like ti-qspi) provide special memory mapped port
>> to accesses SPI flash devices in order to increase read performance.
>> This means the controller can automatically send the SPI signals
>> required to read data from the SPI flash device.
>> For this, spi controller needs to know flash specific information like
>> read command to use, dummy bytes and address width. Once these settings
>> are populated in hardware registers, any read accesses to flash's memory
>> map region(SoC specific) through memcpy (or mem-to mem DMA copy) will be
>> handled by controller hardware. The hardware will automatically generate
>> SPI signals required to read data from flash and present it to CPU/DMA.
>>
>> Introduce spi_mtd_mmap_read() interface to support memory mapped read
>> over SPI flash devices. SPI master drivers can implement this callback to
>> support memory mapped read interfaces. m25p80 flash driver and other
>> flash drivers can call this to request memory mapped read. The interface
>> should only be used MTD flashes and cannot be used with other SPI devices.
>>
>> Signed-off-by: Vignesh R 
>> ---
>>  drivers/spi/spi.c   | 35 +++
>>  include/linux/spi/spi.h | 23 +++
>>  2 files changed, 58 insertions(+)
>>
>> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
>> index a5f53de813d3..5a5c7a7d47f2 100644
>> --- a/drivers/spi/spi.c
>> +++ b/drivers/spi/spi.c
>> @@ -1059,6 +1059,7 @@ static void __spi_pump_messages(struct spi_master 
>> *master, bool in_kthread)
>> }
>> }
>>
>> +   mutex_lock(>mmap_lock_mutex);
>> trace_spi_message_start(master->cur_msg);
>>
>> if (master->prepare_message) {
>> @@ -1068,6 +1069,7 @@ static void __spi_pump_messages(struct spi_master 
>> *master, bool in_kthread)
>> "failed to prepare message: %d\n", ret);
>> master->cur_msg->status = ret;
>> spi_finalize_current_message(master);
>> +   mutex_unlock(>mmap_lock_mutex);
>> return;
>> }
>> master->cur_msg_prepared = true;
>> @@ -1077,6 +1079,7 @@ static void __spi_pump_messages(struct spi_master 
>> *master, bool in_kthread)
>> if (ret) {
>> master->cur_msg->status = ret;
>> spi_finalize_current_message(master);
>> +   mutex_unlock(>mmap_lock_mutex);
>> return;
>> }
>>
>> @@ -1084,8 +1087,10 @@ static void __spi_pump_messages(struct spi_master 
>> *master, bool in_kthread)
>> if (ret) {
>> dev_err(>dev,
>> "failed to transfer one message from queue\n");
>> +   mutex_unlock(>mmap_lock_mutex);
>> return;
>> }
>> +   mutex_unlock(>mmap_lock_mutex);
>>  }
>>
>>  /**
>> @@ -1732,6 +1737,7 @@ int spi_register_master(struct spi_master *master)
>> spin_lock_init(>queue_lock);
>> spin_lock_init(>bus_lock_spinlock);
>> mutex_init(>bus_lock_mutex);
>> +   mutex_init(>mmap_lock_mutex);
>> master->bus_lock_flag = 0;
>> init_completion(>xfer_completion);
>> if (!master->max_dma_len)
>> @@ -2237,6 +2243,35 @@ int spi_async_locked(struct spi_device *spi, struct 
>> spi_message *message)
>>  EXPORT_SYMBOL_GPL(spi_async_locked);
>>
>>
>> +int spi_mtd_mmap_read(struct spi_device *spi, loff_t from, size_t len,
>> + size_t *retlen, u_char *buf, u8 read_opcode,
>> + u8 addr_width, u8 dummy_bytes)
>> +
>> +{
>> +   struct spi_master *master = spi->master;
>> +   int ret;
>> +
>> +   if (master->auto_runtime_pm) {
>> +   ret = pm_runtime_get_sync(master->dev.parent);
>> +   if (ret < 0) {
>> +   dev_err(>dev, "Failed to power device: %d\n",
>> +   ret);
>> +   goto err;
>> +   }
>> +   }
>> +   mutex_lock(>mmap_lock_mutex);
>> +   ret = master->spi_mtd_mmap_read(spi, from, len, retlen, buf,
>> +   read_opcode, addr_width,
>> +   dummy_bytes);
>> +   mutex_unlock(>mmap_lock_mutex);
>> +   if (master->auto_runtime_pm)
>> +   pm_runtime_put(master->dev.parent);
>> +
>> +err:
>> +   return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(spi_mtd_mmap_read);
>> +
>>  
>> /*-*/
>>
>>  /* Utility methods for SPI master protocol drivers, layered on
>> diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
>> index 6b00f18f5e6b..0a6d8ad57357 100644
>> --- a/include/linux/spi/spi.h
>> +++ 

Re: [PATCH v2 1/5] spi: introduce mmap read support for spi flash devices

[Michal Suchanek]

On 3 November 2015 at 11:06, Vignesh R  wrote:
> In addition to providing direct access to SPI bus, some spi controller
> hardwares (like ti-qspi) provide special memory mapped port
> to accesses SPI flash devices in order to increase read performance.
> This means the controller can automatically send the SPI signals
> required to read data from the SPI flash device.
> For this, spi controller needs to know flash specific information like
> read command to use, dummy bytes and address width. Once these settings
> are populated in hardware registers, any read accesses to flash's memory
> map region(SoC specific) through memcpy (or mem-to mem DMA copy) will be
> handled by controller hardware. The hardware will automatically generate
> SPI signals required to read data from flash and present it to CPU/DMA.
>
> Introduce spi_mtd_mmap_read() interface to support memory mapped read
> over SPI flash devices. SPI master drivers can implement this callback to
> support memory mapped read interfaces. m25p80 flash driver and other
> flash drivers can call this to request memory mapped read. The interface
> should only be used MTD flashes and cannot be used with other SPI devices.
>
> Signed-off-by: Vignesh R 
> ---
>  drivers/spi/spi.c   | 35 +++
>  include/linux/spi/spi.h | 23 +++
>  2 files changed, 58 insertions(+)
>
> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
> index a5f53de813d3..5a5c7a7d47f2 100644
> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -1059,6 +1059,7 @@ static void __spi_pump_messages(struct spi_master 
> *master, bool in_kthread)
> }
> }
>
> +   mutex_lock(>mmap_lock_mutex);
> trace_spi_message_start(master->cur_msg);
>
> if (master->prepare_message) {
> @@ -1068,6 +1069,7 @@ static void __spi_pump_messages(struct spi_master 
> *master, bool in_kthread)
> "failed to prepare message: %d\n", ret);
> master->cur_msg->status = ret;
> spi_finalize_current_message(master);
> +   mutex_unlock(>mmap_lock_mutex);
> return;
> }
> master->cur_msg_prepared = true;
> @@ -1077,6 +1079,7 @@ static void __spi_pump_messages(struct spi_master 
> *master, bool in_kthread)
> if (ret) {
> master->cur_msg->status = ret;
> spi_finalize_current_message(master);
> +   mutex_unlock(>mmap_lock_mutex);
> return;
> }
>
> @@ -1084,8 +1087,10 @@ static void __spi_pump_messages(struct spi_master 
> *master, bool in_kthread)
> if (ret) {
> dev_err(>dev,
> "failed to transfer one message from queue\n");
> +   mutex_unlock(>mmap_lock_mutex);
> return;
> }
> +   mutex_unlock(>mmap_lock_mutex);
>  }
>
>  /**
> @@ -1732,6 +1737,7 @@ int spi_register_master(struct spi_master *master)
> spin_lock_init(>queue_lock);
> spin_lock_init(>bus_lock_spinlock);
> mutex_init(>bus_lock_mutex);
> +   mutex_init(>mmap_lock_mutex);
> master->bus_lock_flag = 0;
> init_completion(>xfer_completion);
> if (!master->max_dma_len)
> @@ -2237,6 +2243,35 @@ int spi_async_locked(struct spi_device *spi, struct 
> spi_message *message)
>  EXPORT_SYMBOL_GPL(spi_async_locked);
>
>
> +int spi_mtd_mmap_read(struct spi_device *spi, loff_t from, size_t len,
> + size_t *retlen, u_char *buf, u8 read_opcode,
> + u8 addr_width, u8 dummy_bytes)
> +
> +{
> +   struct spi_master *master = spi->master;
> +   int ret;
> +
> +   if (master->auto_runtime_pm) {
> +   ret = pm_runtime_get_sync(master->dev.parent);
> +   if (ret < 0) {
> +   dev_err(>dev, "Failed to power device: %d\n",
> +   ret);
> +   goto err;
> +   }
> +   }
> +   mutex_lock(>mmap_lock_mutex);
> +   ret = master->spi_mtd_mmap_read(spi, from, len, retlen, buf,
> +   read_opcode, addr_width,
> +   dummy_bytes);
> +   mutex_unlock(>mmap_lock_mutex);
> +   if (master->auto_runtime_pm)
> +   pm_runtime_put(master->dev.parent);
> +
> +err:
> +   return ret;
> +}
> +EXPORT_SYMBOL_GPL(spi_mtd_mmap_read);
> +
>  /*-*/
>
>  /* Utility methods for SPI master protocol drivers, layered on
> diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
> index 6b00f18f5e6b..0a6d8ad57357 100644
> --- a/include/linux/spi/spi.h
> +++ b/include/linux/spi/spi.h
> @@ -297,6 +297,7 @@ static inline void spi_unregister_driver(struct 
> spi_driver *sdrv)
>   * @flags: other constraints relevant to this driver
>   * 

[PATCH v2 1/5] spi: introduce mmap read support for spi flash devices

[Vignesh R]

In addition to providing direct access to SPI bus, some spi controller
hardwares (like ti-qspi) provide special memory mapped port
to accesses SPI flash devices in order to increase read performance.
This means the controller can automatically send the SPI signals
required to read data from the SPI flash device.
For this, spi controller needs to know flash specific information like
read command to use, dummy bytes and address width. Once these settings
are populated in hardware registers, any read accesses to flash's memory
map region(SoC specific) through memcpy (or mem-to mem DMA copy) will be
handled by controller hardware. The hardware will automatically generate
SPI signals required to read data from flash and present it to CPU/DMA.

Introduce spi_mtd_mmap_read() interface to support memory mapped read
over SPI flash devices. SPI master drivers can implement this callback to
support memory mapped read interfaces. m25p80 flash driver and other
flash drivers can call this to request memory mapped read. The interface
should only be used MTD flashes and cannot be used with other SPI devices.

Signed-off-by: Vignesh R 
---
 drivers/spi/spi.c   | 35 +++
 include/linux/spi/spi.h | 23 +++
 2 files changed, 58 insertions(+)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index a5f53de813d3..5a5c7a7d47f2 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1059,6 +1059,7 @@ static void __spi_pump_messages(struct spi_master 
*master, bool in_kthread)
}
}
 
+   mutex_lock(>mmap_lock_mutex);
trace_spi_message_start(master->cur_msg);
 
if (master->prepare_message) {
@@ -1068,6 +1069,7 @@ static void __spi_pump_messages(struct spi_master 
*master, bool in_kthread)
"failed to prepare message: %d\n", ret);
master->cur_msg->status = ret;
spi_finalize_current_message(master);
+   mutex_unlock(>mmap_lock_mutex);
return;
}
master->cur_msg_prepared = true;
@@ -1077,6 +1079,7 @@ static void __spi_pump_messages(struct spi_master 
*master, bool in_kthread)
if (ret) {
master->cur_msg->status = ret;
spi_finalize_current_message(master);
+   mutex_unlock(>mmap_lock_mutex);
return;
}
 
@@ -1084,8 +1087,10 @@ static void __spi_pump_messages(struct spi_master 
*master, bool in_kthread)
if (ret) {
dev_err(>dev,
"failed to transfer one message from queue\n");
+   mutex_unlock(>mmap_lock_mutex);
return;
}
+   mutex_unlock(>mmap_lock_mutex);
 }
 
 /**
@@ -1732,6 +1737,7 @@ int spi_register_master(struct spi_master *master)
spin_lock_init(>queue_lock);
spin_lock_init(>bus_lock_spinlock);
mutex_init(>bus_lock_mutex);
+   mutex_init(>mmap_lock_mutex);
master->bus_lock_flag = 0;
init_completion(>xfer_completion);
if (!master->max_dma_len)
@@ -2237,6 +2243,35 @@ int spi_async_locked(struct spi_device *spi, struct 
spi_message *message)
 EXPORT_SYMBOL_GPL(spi_async_locked);
 
 
+int spi_mtd_mmap_read(struct spi_device *spi, loff_t from, size_t len,
+ size_t *retlen, u_char *buf, u8 read_opcode,
+ u8 addr_width, u8 dummy_bytes)
+
+{
+   struct spi_master *master = spi->master;
+   int ret;
+
+   if (master->auto_runtime_pm) {
+   ret = pm_runtime_get_sync(master->dev.parent);
+   if (ret < 0) {
+   dev_err(>dev, "Failed to power device: %d\n",
+   ret);
+   goto err;
+   }
+   }
+   mutex_lock(>mmap_lock_mutex);
+   ret = master->spi_mtd_mmap_read(spi, from, len, retlen, buf,
+   read_opcode, addr_width,
+   dummy_bytes);
+   mutex_unlock(>mmap_lock_mutex);
+   if (master->auto_runtime_pm)
+   pm_runtime_put(master->dev.parent);
+
+err:
+   return ret;
+}
+EXPORT_SYMBOL_GPL(spi_mtd_mmap_read);
+
 /*-*/
 
 /* Utility methods for SPI master protocol drivers, layered on
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 6b00f18f5e6b..0a6d8ad57357 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -297,6 +297,7 @@ static inline void spi_unregister_driver(struct spi_driver 
*sdrv)
  * @flags: other constraints relevant to this driver
  * @bus_lock_spinlock: spinlock for SPI bus locking
  * @bus_lock_mutex: mutex for SPI bus locking
+ * @mmap_lock_mutex: mutex for locking SPI bus when mmap transfer is on.
  * @bus_lock_flag: indicates that the SPI bus is locked for exclusive use
  * @setup: updates the device 

[PATCH v2 1/5] spi: introduce mmap read support for spi flash devices

[Vignesh R]

In addition to providing direct access to SPI bus, some spi controller
hardwares (like ti-qspi) provide special memory mapped port
to accesses SPI flash devices in order to increase read performance.
This means the controller can automatically send the SPI signals
required to read data from the SPI flash device.
For this, spi controller needs to know flash specific information like
read command to use, dummy bytes and address width. Once these settings
are populated in hardware registers, any read accesses to flash's memory
map region(SoC specific) through memcpy (or mem-to mem DMA copy) will be
handled by controller hardware. The hardware will automatically generate
SPI signals required to read data from flash and present it to CPU/DMA.

Introduce spi_mtd_mmap_read() interface to support memory mapped read
over SPI flash devices. SPI master drivers can implement this callback to
support memory mapped read interfaces. m25p80 flash driver and other
flash drivers can call this to request memory mapped read. The interface
should only be used MTD flashes and cannot be used with other SPI devices.

Signed-off-by: Vignesh R 
---
 drivers/spi/spi.c   | 35 +++
 include/linux/spi/spi.h | 23 +++
 2 files changed, 58 insertions(+)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index a5f53de813d3..5a5c7a7d47f2 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1059,6 +1059,7 @@ static void __spi_pump_messages(struct spi_master 
*master, bool in_kthread)
}
}
 
+   mutex_lock(>mmap_lock_mutex);
trace_spi_message_start(master->cur_msg);
 
if (master->prepare_message) {
@@ -1068,6 +1069,7 @@ static void __spi_pump_messages(struct spi_master 
*master, bool in_kthread)
"failed to prepare message: %d\n", ret);
master->cur_msg->status = ret;
spi_finalize_current_message(master);
+   mutex_unlock(>mmap_lock_mutex);
return;
}
master->cur_msg_prepared = true;
@@ -1077,6 +1079,7 @@ static void __spi_pump_messages(struct spi_master 
*master, bool in_kthread)
if (ret) {
master->cur_msg->status = ret;
spi_finalize_current_message(master);
+   mutex_unlock(>mmap_lock_mutex);
return;
}
 
@@ -1084,8 +1087,10 @@ static void __spi_pump_messages(struct spi_master 
*master, bool in_kthread)
if (ret) {
dev_err(>dev,
"failed to transfer one message from queue\n");
+   mutex_unlock(>mmap_lock_mutex);
return;
}
+   mutex_unlock(>mmap_lock_mutex);
 }
 
 /**
@@ -1732,6 +1737,7 @@ int spi_register_master(struct spi_master *master)
spin_lock_init(>queue_lock);
spin_lock_init(>bus_lock_spinlock);
mutex_init(>bus_lock_mutex);
+   mutex_init(>mmap_lock_mutex);
master->bus_lock_flag = 0;
init_completion(>xfer_completion);
if (!master->max_dma_len)
@@ -2237,6 +2243,35 @@ int spi_async_locked(struct spi_device *spi, struct 
spi_message *message)
 EXPORT_SYMBOL_GPL(spi_async_locked);
 
 
+int spi_mtd_mmap_read(struct spi_device *spi, loff_t from, size_t len,
+ size_t *retlen, u_char *buf, u8 read_opcode,
+ u8 addr_width, u8 dummy_bytes)
+
+{
+   struct spi_master *master = spi->master;
+   int ret;
+
+   if (master->auto_runtime_pm) {
+   ret = pm_runtime_get_sync(master->dev.parent);
+   if (ret < 0) {
+   dev_err(>dev, "Failed to power device: %d\n",
+   ret);
+   goto err;
+   }
+   }
+   mutex_lock(>mmap_lock_mutex);
+   ret = master->spi_mtd_mmap_read(spi, from, len, retlen, buf,
+   read_opcode, addr_width,
+   dummy_bytes);
+   mutex_unlock(>mmap_lock_mutex);
+   if (master->auto_runtime_pm)
+   pm_runtime_put(master->dev.parent);
+
+err:
+   return ret;
+}
+EXPORT_SYMBOL_GPL(spi_mtd_mmap_read);
+
 /*-*/
 
 /* Utility methods for SPI master protocol drivers, layered on
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 6b00f18f5e6b..0a6d8ad57357 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -297,6 +297,7 @@ static inline void spi_unregister_driver(struct spi_driver 
*sdrv)
  * @flags: other constraints relevant to this driver
  * @bus_lock_spinlock: spinlock for SPI bus locking
  * @bus_lock_mutex: mutex for SPI bus locking
+ * @mmap_lock_mutex: mutex for locking SPI bus when mmap transfer is on.
  * @bus_lock_flag: indicates that the SPI bus is locked for exclusive use
  * @setup: 

Re: [PATCH v2 1/5] spi: introduce mmap read support for spi flash devices

[Michal Suchanek]

On 3 November 2015 at 11:06, Vignesh R  wrote:
> In addition to providing direct access to SPI bus, some spi controller
> hardwares (like ti-qspi) provide special memory mapped port
> to accesses SPI flash devices in order to increase read performance.
> This means the controller can automatically send the SPI signals
> required to read data from the SPI flash device.
> For this, spi controller needs to know flash specific information like
> read command to use, dummy bytes and address width. Once these settings
> are populated in hardware registers, any read accesses to flash's memory
> map region(SoC specific) through memcpy (or mem-to mem DMA copy) will be
> handled by controller hardware. The hardware will automatically generate
> SPI signals required to read data from flash and present it to CPU/DMA.
>
> Introduce spi_mtd_mmap_read() interface to support memory mapped read
> over SPI flash devices. SPI master drivers can implement this callback to
> support memory mapped read interfaces. m25p80 flash driver and other
> flash drivers can call this to request memory mapped read. The interface
> should only be used MTD flashes and cannot be used with other SPI devices.
>
> Signed-off-by: Vignesh R 
> ---
>  drivers/spi/spi.c   | 35 +++
>  include/linux/spi/spi.h | 23 +++
>  2 files changed, 58 insertions(+)
>
> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
> index a5f53de813d3..5a5c7a7d47f2 100644
> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -1059,6 +1059,7 @@ static void __spi_pump_messages(struct spi_master 
> *master, bool in_kthread)
> }
> }
>
> +   mutex_lock(>mmap_lock_mutex);
> trace_spi_message_start(master->cur_msg);
>
> if (master->prepare_message) {
> @@ -1068,6 +1069,7 @@ static void __spi_pump_messages(struct spi_master 
> *master, bool in_kthread)
> "failed to prepare message: %d\n", ret);
> master->cur_msg->status = ret;
> spi_finalize_current_message(master);
> +   mutex_unlock(>mmap_lock_mutex);
> return;
> }
> master->cur_msg_prepared = true;
> @@ -1077,6 +1079,7 @@ static void __spi_pump_messages(struct spi_master 
> *master, bool in_kthread)
> if (ret) {
> master->cur_msg->status = ret;
> spi_finalize_current_message(master);
> +   mutex_unlock(>mmap_lock_mutex);
> return;
> }
>
> @@ -1084,8 +1087,10 @@ static void __spi_pump_messages(struct spi_master 
> *master, bool in_kthread)
> if (ret) {
> dev_err(>dev,
> "failed to transfer one message from queue\n");
> +   mutex_unlock(>mmap_lock_mutex);
> return;
> }
> +   mutex_unlock(>mmap_lock_mutex);
>  }
>
>  /**
> @@ -1732,6 +1737,7 @@ int spi_register_master(struct spi_master *master)
> spin_lock_init(>queue_lock);
> spin_lock_init(>bus_lock_spinlock);
> mutex_init(>bus_lock_mutex);
> +   mutex_init(>mmap_lock_mutex);
> master->bus_lock_flag = 0;
> init_completion(>xfer_completion);
> if (!master->max_dma_len)
> @@ -2237,6 +2243,35 @@ int spi_async_locked(struct spi_device *spi, struct 
> spi_message *message)
>  EXPORT_SYMBOL_GPL(spi_async_locked);
>
>
> +int spi_mtd_mmap_read(struct spi_device *spi, loff_t from, size_t len,
> + size_t *retlen, u_char *buf, u8 read_opcode,
> + u8 addr_width, u8 dummy_bytes)
> +
> +{
> +   struct spi_master *master = spi->master;
> +   int ret;
> +
> +   if (master->auto_runtime_pm) {
> +   ret = pm_runtime_get_sync(master->dev.parent);
> +   if (ret < 0) {
> +   dev_err(>dev, "Failed to power device: %d\n",
> +   ret);
> +   goto err;
> +   }
> +   }
> +   mutex_lock(>mmap_lock_mutex);
> +   ret = master->spi_mtd_mmap_read(spi, from, len, retlen, buf,
> +   read_opcode, addr_width,
> +   dummy_bytes);
> +   mutex_unlock(>mmap_lock_mutex);
> +   if (master->auto_runtime_pm)
> +   pm_runtime_put(master->dev.parent);
> +
> +err:
> +   return ret;
> +}
> +EXPORT_SYMBOL_GPL(spi_mtd_mmap_read);
> +
>  /*-*/
>
>  /* Utility methods for SPI master protocol drivers, layered on
> diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
> index 6b00f18f5e6b..0a6d8ad57357 100644
> --- a/include/linux/spi/spi.h
> +++ b/include/linux/spi/spi.h
> @@ -297,6 +297,7 @@ static inline void spi_unregister_driver(struct 
> spi_driver *sdrv)
>   * @flags: other constraints 

Re: [PATCH v2 1/5] spi: introduce mmap read support for spi flash devices

[Vignesh R]

Hi,

On 11/03/2015 04:49 PM, Michal Suchanek wrote:
> On 3 November 2015 at 11:06, Vignesh R  wrote:
>> In addition to providing direct access to SPI bus, some spi controller
>> hardwares (like ti-qspi) provide special memory mapped port
>> to accesses SPI flash devices in order to increase read performance.
>> This means the controller can automatically send the SPI signals
>> required to read data from the SPI flash device.
>> For this, spi controller needs to know flash specific information like
>> read command to use, dummy bytes and address width. Once these settings
>> are populated in hardware registers, any read accesses to flash's memory
>> map region(SoC specific) through memcpy (or mem-to mem DMA copy) will be
>> handled by controller hardware. The hardware will automatically generate
>> SPI signals required to read data from flash and present it to CPU/DMA.
>>
>> Introduce spi_mtd_mmap_read() interface to support memory mapped read
>> over SPI flash devices. SPI master drivers can implement this callback to
>> support memory mapped read interfaces. m25p80 flash driver and other
>> flash drivers can call this to request memory mapped read. The interface
>> should only be used MTD flashes and cannot be used with other SPI devices.
>>
>> Signed-off-by: Vignesh R 
>> ---
>>  drivers/spi/spi.c   | 35 +++
>>  include/linux/spi/spi.h | 23 +++
>>  2 files changed, 58 insertions(+)
>>
>> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
>> index a5f53de813d3..5a5c7a7d47f2 100644
>> --- a/drivers/spi/spi.c
>> +++ b/drivers/spi/spi.c
>> @@ -1059,6 +1059,7 @@ static void __spi_pump_messages(struct spi_master 
>> *master, bool in_kthread)
>> }
>> }
>>
>> +   mutex_lock(>mmap_lock_mutex);
>> trace_spi_message_start(master->cur_msg);
>>
>> if (master->prepare_message) {
>> @@ -1068,6 +1069,7 @@ static void __spi_pump_messages(struct spi_master 
>> *master, bool in_kthread)
>> "failed to prepare message: %d\n", ret);
>> master->cur_msg->status = ret;
>> spi_finalize_current_message(master);
>> +   mutex_unlock(>mmap_lock_mutex);
>> return;
>> }
>> master->cur_msg_prepared = true;
>> @@ -1077,6 +1079,7 @@ static void __spi_pump_messages(struct spi_master 
>> *master, bool in_kthread)
>> if (ret) {
>> master->cur_msg->status = ret;
>> spi_finalize_current_message(master);
>> +   mutex_unlock(>mmap_lock_mutex);
>> return;
>> }
>>
>> @@ -1084,8 +1087,10 @@ static void __spi_pump_messages(struct spi_master 
>> *master, bool in_kthread)
>> if (ret) {
>> dev_err(>dev,
>> "failed to transfer one message from queue\n");
>> +   mutex_unlock(>mmap_lock_mutex);
>> return;
>> }
>> +   mutex_unlock(>mmap_lock_mutex);
>>  }
>>
>>  /**
>> @@ -1732,6 +1737,7 @@ int spi_register_master(struct spi_master *master)
>> spin_lock_init(>queue_lock);
>> spin_lock_init(>bus_lock_spinlock);
>> mutex_init(>bus_lock_mutex);
>> +   mutex_init(>mmap_lock_mutex);
>> master->bus_lock_flag = 0;
>> init_completion(>xfer_completion);
>> if (!master->max_dma_len)
>> @@ -2237,6 +2243,35 @@ int spi_async_locked(struct spi_device *spi, struct 
>> spi_message *message)
>>  EXPORT_SYMBOL_GPL(spi_async_locked);
>>
>>
>> +int spi_mtd_mmap_read(struct spi_device *spi, loff_t from, size_t len,
>> + size_t *retlen, u_char *buf, u8 read_opcode,
>> + u8 addr_width, u8 dummy_bytes)
>> +
>> +{
>> +   struct spi_master *master = spi->master;
>> +   int ret;
>> +
>> +   if (master->auto_runtime_pm) {
>> +   ret = pm_runtime_get_sync(master->dev.parent);
>> +   if (ret < 0) {
>> +   dev_err(>dev, "Failed to power device: %d\n",
>> +   ret);
>> +   goto err;
>> +   }
>> +   }
>> +   mutex_lock(>mmap_lock_mutex);
>> +   ret = master->spi_mtd_mmap_read(spi, from, len, retlen, buf,
>> +   read_opcode, addr_width,
>> +   dummy_bytes);
>> +   mutex_unlock(>mmap_lock_mutex);
>> +   if (master->auto_runtime_pm)
>> +   pm_runtime_put(master->dev.parent);
>> +
>> +err:
>> +   return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(spi_mtd_mmap_read);
>> +
>>  
>> /*-*/
>>
>>  /* Utility methods for SPI master protocol drivers, layered on
>> diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
>> index 6b00f18f5e6b..0a6d8ad57357 100644
>> ---