[Skiboot] [PATCH V2 4/4] libflash/mbox-flash: Implement MARK_WRITE_ERASED mbox call

[Cyril Bur]

On Wed, 2017-05-24 at 16:37 +1000, Suraj Jitindar Singh wrote:
> Version two of the mbox-flash protocol defines a new command:
> MARK_WRITE_ERASED.
> 
> This command provides a simple way to mark a region of flash as all 0xff
> without the need to go and write all 0xff. This is an optimisation as
> there is no need for an erase before a write, it is the responsibility of
> the BMC to deal with the flash correctly, however in v1 it was ambiguous
> what a client should do if the flash should be erased but not actually
> written to. This allows of a optimal path to resolve this problem.
> 
> Signed-off-by: Cyril Bur <cyril.bur at au1.ibm.com>
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh at gmail.com>
> 

Acked-by: Cyril Bur <cyril.bur at au1.ibm.com>

> ---
> 
> V1 -> V2:
> 
> - Rework to utilise general mark_write function to ensure correctness
> ---
>  libflash/mbox-flash.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++----
>  1 file changed, 59 insertions(+), 4 deletions(-)
> 
> diff --git a/libflash/mbox-flash.c b/libflash/mbox-flash.c
> index 5de743a..7491d3b 100644
> --- a/libflash/mbox-flash.c
> +++ b/libflash/mbox-flash.c
> @@ -530,6 +530,18 @@ static int mbox_flash_dirty(struct mbox_flash_data *mbox_flash, uint64_t pos,
>  				     MBOX_C_MARK_WRITE_DIRTY);
>  }
>  
> +static int mbox_flash_erase(struct mbox_flash_data *mbox_flash, uint64_t pos,
> +			    uint64_t len)
> +{
> +	if (!mbox_flash->write.open) {
> +		prlog(PR_ERR, "Attempting to erase without an open write window\n");
> +		return FLASH_ERR_DEVICE_GONE;
> +	}
> +
> +	return mbox_flash_mark_write(mbox_flash, pos, len,
> +				     MBOX_C_MARK_WRITE_ERASED);
> +}
> +
>  static int mbox_flash_flush(struct mbox_flash_data *mbox_flash)
>  {
>  	struct bmc_mbox_msg *msg;
> @@ -782,8 +794,50 @@ out:
>  	return rc;
>  }
>  
> -static int mbox_flash_erase(struct blocklevel_device *bl __unused,
> -		uint64_t pos __unused, uint64_t len __unused)
> +static int mbox_flash_erase_v2(struct blocklevel_device *bl, uint64_t pos,
> +			       uint64_t len)
> +{
> +	struct mbox_flash_data *mbox_flash;
> +
> +	/* LPC is only 32bit */
> +	if (pos > UINT_MAX || len > UINT_MAX)
> +		return FLASH_ERR_PARM_ERROR;
> +
> +	mbox_flash = container_of(bl, struct mbox_flash_data, bl);
> +
> +	prlog(PR_TRACE, "Flash erase at 0x%08x for 0x%08x\n", (u32) pos, (u32) len);
> +	while (len > 0) {
> +		uint64_t size;
> +		int rc;
> +
> +		/* Move window and get a new size to erase */
> +		rc = mbox_window_move(mbox_flash, &mbox_flash->write,
> +				      MBOX_C_CREATE_WRITE_WINDOW, pos, len, &size);
> +		if (rc)
> +			return rc;
> +
> +		rc = mbox_flash_erase(mbox_flash, pos, size);
> +		if (rc)
> +			return rc;
> +
> +		/*
> +		* Flush directly, don't mark that region dirty otherwise it
> +		* isn't clear if a write happened there or not
> +		*/
> +
> +		rc = mbox_flash_flush(mbox_flash);
> +		if (rc)
> +			return rc;
> +
> +		len -= size;
> +		pos += size;
> +	}
> +
> +	return 0;
> +}
> +
> +static int mbox_flash_erase_v1(struct blocklevel_device *bl __unused,
> +			       uint64_t pos __unused, uint64_t len __unused)
>  {
>  	/*
>  	* We can probably get away with doing nothing.
> @@ -880,7 +934,7 @@ static int protocol_init(struct mbox_flash_data *mbox_flash)
>  	/* Assume V2 */
>  	mbox_flash->bl.read = &mbox_flash_read;
>  	mbox_flash->bl.write = &mbox_flash_write;
> -	mbox_flash->bl.erase = &mbox_flash_erase;
> +	mbox_flash->bl.erase = &mbox_flash_erase_v2;
>  	mbox_flash->bl.get_info = &mbox_flash_get_info;
>  
>  	/* Assume V2 */
> @@ -934,6 +988,7 @@ static int protocol_init(struct mbox_flash_data *mbox_flash)
>  
>  	prlog(PR_INFO, "Detected mbox protocol version %d\n", mbox_flash->version);
>  	if (mbox_flash->version == 1) {
> +		mbox_flash->bl.erase = &mbox_flash_erase_v1;
>  		/* Not all handlers differ, update those which do */
>  		mbox_flash->handlers[MBOX_C_GET_FLASH_INFO] = &mbox_flash_do_get_flash_info_v1;
>  		mbox_flash->handlers[MBOX_C_CREATE_READ_WINDOW] =
> @@ -976,7 +1031,7 @@ int mbox_flash_init(struct blocklevel_device **bl)
>  	/* Assume V2 */
>  	mbox_flash->bl.read = &mbox_flash_read;
>  	mbox_flash->bl.write = &mbox_flash_write;
> -	mbox_flash->bl.erase = &mbox_flash_erase;
> +	mbox_flash->bl.erase = &mbox_flash_erase_v2;
>  	mbox_flash->bl.get_info = &mbox_flash_get_info;
>  
>  	if (bmc_mbox_get_attn_reg() & MBOX_ATTN_BMC_REBOOT)