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Message-ID: <dd9ab7d1-5c03-404a-90c7-7ccbc0fb5c4c@linux.intel.com>
Date: Tue, 27 Feb 2024 18:38:37 -0800
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Subject: Re: [PATCH V2 2/9] platform/x86/intel/sdsi: Combine read and write
 mailbox flows
Content-Language: en-US
To: "David E. Box" <david.e.box@linux.intel.com>,
 rajvi.jingar@linux.intel.com, platform-driver-x86@vger.kernel.org,
 linux-kernel@vger.kernel.org, hdegoede@redhat.com,
 ilpo.jarvinen@linux.intel.com
References: <20240228000016.1685518-1-david.e.box@linux.intel.com>
 <20240228000016.1685518-3-david.e.box@linux.intel.com>
From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
In-Reply-To: <20240228000016.1685518-3-david.e.box@linux.intel.com>
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On 2/27/24 4:00 PM, David E. Box wrote:
> The current mailbox commands are either read-only or write-only and the
> flow is different for each. New commands will need to send and receive
> data. In preparation for these commands, create a common polling function
> to handle sending data and receiving in the same transaction.
>
> Signed-off-by: David E. Box <david.e.box@linux.intel.com>
> ---
>
> V2 - In sdsi_cmd_read() remove unnecessary check for non-zero packet_size
>      in do loop since the loop is exited earlier when packet_size is
>      zero.
>
>  drivers/platform/x86/intel/sdsi.c | 79 +++++++++++++++++--------------
>  1 file changed, 44 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/platform/x86/intel/sdsi.c b/drivers/platform/x86/intel/sdsi.c
> index a70c071de6e2..d80c2dc0ce71 100644
> --- a/drivers/platform/x86/intel/sdsi.c
> +++ b/drivers/platform/x86/intel/sdsi.c
> @@ -15,6 +15,7 @@
>  #include <linux/iopoll.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
> +#include <linux/overflow.h>
>  #include <linux/pci.h>
>  #include <linux/slab.h>
>  #include <linux/sysfs.h>
> @@ -156,8 +157,8 @@ static int sdsi_status_to_errno(u32 status)
>  	}
>  }
>  
> -static int sdsi_mbox_cmd_read(struct sdsi_priv *priv, struct sdsi_mbox_info *info,
> -			      size_t *data_size)
> +static int sdsi_mbox_poll(struct sdsi_priv *priv, struct sdsi_mbox_info *info,
> +			  size_t *data_size)
>  {
>  	struct device *dev = priv->dev;
>  	u32 total, loop, eom, status, message_size;
> @@ -166,18 +167,10 @@ static int sdsi_mbox_cmd_read(struct sdsi_priv *priv, struct sdsi_mbox_info *inf
>  
>  	lockdep_assert_held(&priv->mb_lock);
>  
> -	/* Format and send the read command */
> -	control = FIELD_PREP(CTRL_EOM, 1) |
> -		  FIELD_PREP(CTRL_SOM, 1) |
> -		  FIELD_PREP(CTRL_RUN_BUSY, 1) |
> -		  FIELD_PREP(CTRL_PACKET_SIZE, info->size);
> -	writeq(control, priv->control_addr);
> -
>  	/* For reads, data sizes that are larger than the mailbox size are read in packets. */
>  	total = 0;
>  	loop = 0;
>  	do {
> -		void *buf = info->buffer + (SDSI_SIZE_MAILBOX * loop);
>  		u32 packet_size;
>  
>  		/* Poll on ready bit */
> @@ -195,6 +188,11 @@ static int sdsi_mbox_cmd_read(struct sdsi_priv *priv, struct sdsi_mbox_info *inf
>  		if (ret)
>  			break;
>  
> +		if (!packet_size) {
> +			sdsi_complete_transaction(priv);
> +			break;
> +		}
> +
>  		/* Only the last packet can be less than the mailbox size. */
>  		if (!eom && packet_size != SDSI_SIZE_MAILBOX) {
>  			dev_err(dev, "Invalid packet size\n");
> @@ -208,9 +206,13 @@ static int sdsi_mbox_cmd_read(struct sdsi_priv *priv, struct sdsi_mbox_info *inf
>  			break;
>  		}
>  
> -		sdsi_memcpy64_fromio(buf, priv->mbox_addr, round_up(packet_size, SDSI_SIZE_CMD));
> +		if (info->buffer) {
> +			void *buf = info->buffer + array_size(SDSI_SIZE_MAILBOX, loop);
>  
> -		total += packet_size;
> +			sdsi_memcpy64_fromio(buf, priv->mbox_addr,
> +					     round_up(packet_size, SDSI_SIZE_CMD));
> +			total += packet_size;
> +		}
>  
>  		sdsi_complete_transaction(priv);
>  	} while (!eom && ++loop < MBOX_MAX_PACKETS);
> @@ -230,16 +232,33 @@ static int sdsi_mbox_cmd_read(struct sdsi_priv *priv, struct sdsi_mbox_info *inf
>  		dev_warn(dev, "Read count %u differs from expected count %u\n",
>  			 total, message_size);
>  
> -	*data_size = total;
> +	if (data_size)
> +		*data_size = total;
>  

Is there a chance for it to be NULL with current callers?

>  	return 0;
>  }
>  
> -static int sdsi_mbox_cmd_write(struct sdsi_priv *priv, struct sdsi_mbox_info *info)
> +static int sdsi_mbox_cmd_read(struct sdsi_priv *priv, struct sdsi_mbox_info *info,
> +			      size_t *data_size)
> +{
> +	u64 control;
> +
> +	lockdep_assert_held(&priv->mb_lock);
> +
> +	/* Format and send the read command */
> +	control = FIELD_PREP(CTRL_EOM, 1) |
> +		  FIELD_PREP(CTRL_SOM, 1) |
> +		  FIELD_PREP(CTRL_RUN_BUSY, 1) |
> +		  FIELD_PREP(CTRL_PACKET_SIZE, info->size);
> +	writeq(control, priv->control_addr);
> +
> +	return sdsi_mbox_poll(priv, info, data_size);
> +}
> +
> +static int sdsi_mbox_cmd_write(struct sdsi_priv *priv, struct sdsi_mbox_info *info,
> +			       size_t *data_size)
>  {
>  	u64 control;
> -	u32 status;
> -	int ret;
>  
>  	lockdep_assert_held(&priv->mb_lock);
>  
> @@ -256,20 +275,7 @@ static int sdsi_mbox_cmd_write(struct sdsi_priv *priv, struct sdsi_mbox_info *in
>  		  FIELD_PREP(CTRL_PACKET_SIZE, info->size);
>  	writeq(control, priv->control_addr);
>  
> -	/* Poll on ready bit */
> -	ret = readq_poll_timeout(priv->control_addr, control, control & CTRL_READY,
> -				 MBOX_POLLING_PERIOD_US, MBOX_TIMEOUT_US);
> -
> -	if (ret)
> -		goto release_mbox;
> -
> -	status = FIELD_GET(CTRL_STATUS, control);
> -	ret = sdsi_status_to_errno(status);
> -
> -release_mbox:
> -	sdsi_complete_transaction(priv);
> -
> -	return ret;
> +	return sdsi_mbox_poll(priv, info, data_size);
>  }
>  
>  static int sdsi_mbox_acquire(struct sdsi_priv *priv, struct sdsi_mbox_info *info)
> @@ -313,7 +319,8 @@ static int sdsi_mbox_acquire(struct sdsi_priv *priv, struct sdsi_mbox_info *info
>  	return ret;
>  }
>  
> -static int sdsi_mbox_write(struct sdsi_priv *priv, struct sdsi_mbox_info *info)
> +static int sdsi_mbox_write(struct sdsi_priv *priv, struct sdsi_mbox_info *info,
> +			   size_t *data_size)
>  {
>  	int ret;
>  
> @@ -323,7 +330,7 @@ static int sdsi_mbox_write(struct sdsi_priv *priv, struct sdsi_mbox_info *info)
>  	if (ret)
>  		return ret;
>  
> -	return sdsi_mbox_cmd_write(priv, info);
> +	return sdsi_mbox_cmd_write(priv, info, data_size);
>  }
>  
>  static int sdsi_mbox_read(struct sdsi_priv *priv, struct sdsi_mbox_info *info, size_t *data_size)
> @@ -342,7 +349,7 @@ static int sdsi_mbox_read(struct sdsi_priv *priv, struct sdsi_mbox_info *info, s
>  static ssize_t sdsi_provision(struct sdsi_priv *priv, char *buf, size_t count,
>  			      enum sdsi_command command)
>  {
> -	struct sdsi_mbox_info info;
> +	struct sdsi_mbox_info info = {};
>  	int ret;
>  
>  	if (count > (SDSI_SIZE_WRITE_MSG - SDSI_SIZE_CMD))
> @@ -364,7 +371,9 @@ static ssize_t sdsi_provision(struct sdsi_priv *priv, char *buf, size_t count,
>  	ret = mutex_lock_interruptible(&priv->mb_lock);
>  	if (ret)
>  		goto free_payload;
> -	ret = sdsi_mbox_write(priv, &info);
> +
> +	ret = sdsi_mbox_write(priv, &info, NULL);
> +
>  	mutex_unlock(&priv->mb_lock);
>  
>  free_payload:
> @@ -408,7 +417,7 @@ static ssize_t
>  certificate_read(u64 command, struct sdsi_priv *priv, char *buf, loff_t off,
>  		 size_t count)
>  {
> -	struct sdsi_mbox_info info;
> +	struct sdsi_mbox_info info = {};
>  	size_t size;
>  	int ret;
>  

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer