Commit 62f79f3d authored by Eddie James's avatar Eddie James Committed by Joel Stanley
Browse files

fsi: occ: Force sequence numbering per OCC 



Set and increment the sequence number during the submit operation.
This prevents sequence number conflicts between different users of
the interface. A sequence number conflict may result in a user
getting an OCC response meant for a different command. Since the
sequence number is now modified, the checksum must be calculated and
set before submitting the command.

Signed-off-by: default avatarEddie James <eajames@linux.ibm.com>
Reviewed-by: default avatarJoel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20210721190231.117185-2-eajames@linux.ibm.com


Signed-off-by: default avatarJoel Stanley <joel@jms.id.au>
parent 6880fa6c

drivers/fsi/fsi-occ.c

+37 −17
Original line number Diff line number Diff line
@@ -50,6 +50,7 @@ struct occ { 
	struct device *sbefifo;

	char name[32];

	int idx;

	u8 sequence_number;

	enum versions version;

	struct miscdevice mdev;

	struct mutex occ_lock;
@@ -141,8 +142,7 @@ static ssize_t occ_write(struct file *file, const char __user *buf, 
{

	struct occ_client *client = file->private_data;

	size_t rlen, data_length;

	u16 checksum = 0;

	ssize_t rc, i;

	ssize_t rc;

	u8 *cmd;



	if (!client)
@@ -156,9 +156,6 @@ static ssize_t occ_write(struct file *file, const char __user *buf, 
	/* Construct the command */

	cmd = client->buffer;



	/* Sequence number (we could increment and compare with response) */

	cmd[0] = 1;



	/*

	 * Copy the user command (assume user data follows the occ command

	 * format)
@@ -178,14 +175,7 @@ static ssize_t occ_write(struct file *file, const char __user *buf, 
		goto done;

	}



	/* Calculate checksum */

	for (i = 0; i < data_length + 4; ++i)

		checksum += cmd[i];



	cmd[data_length + 4] = checksum >> 8;

	cmd[data_length + 5] = checksum & 0xFF;



	/* Submit command */

	/* Submit command; 4 bytes before the data and 2 bytes after */

	rlen = PAGE_SIZE;

	rc = fsi_occ_submit(client->occ->dev, cmd, data_length + 6, cmd,

			    &rlen);
@@ -314,11 +304,13 @@ static int occ_getsram(struct occ *occ, u32 offset, void *data, ssize_t len) 
	return rc;

}



static int occ_putsram(struct occ *occ, const void *data, ssize_t len)

static int occ_putsram(struct occ *occ, const void *data, ssize_t len,

		       u8 seq_no, u16 checksum)

{

	size_t cmd_len, buf_len, resp_len, resp_data_len;

	u32 data_len = ((len + 7) / 8) * 8;	/* must be multiples of 8 B */

	__be32 *buf;

	u8 *byte_buf;

	int idx = 0, rc;



	cmd_len = (occ->version == occ_p10) ? 6 : 5;
@@ -358,6 +350,15 @@ static int occ_putsram(struct occ *occ, const void *data, ssize_t len) 
	buf[4 + idx] = cpu_to_be32(data_len);

	memcpy(&buf[5 + idx], data, len);



	byte_buf = (u8 *)&buf[5 + idx];

	/*

	 * Overwrite the first byte with our sequence number and the last two

	 * bytes with the checksum.

	 */

	byte_buf[0] = seq_no;

	byte_buf[len - 2] = checksum >> 8;

	byte_buf[len - 1] = checksum & 0xff;



	rc = sbefifo_submit(occ->sbefifo, buf, cmd_len, buf, &resp_len);

	if (rc)

		goto free;
@@ -467,9 +468,12 @@ int fsi_occ_submit(struct device *dev, const void *request, size_t req_len, 
	struct occ *occ = dev_get_drvdata(dev);

	struct occ_response *resp = response;

	u8 seq_no;

	u16 checksum = 0;

	u16 resp_data_length;

	const u8 *byte_request = (const u8 *)request;

	unsigned long start;

	int rc;

	size_t i;



	if (!occ)

		return -ENODEV;
@@ -479,11 +483,26 @@ int fsi_occ_submit(struct device *dev, const void *request, size_t req_len, 
		return -EINVAL;

	}



	/* Checksum the request, ignoring first byte (sequence number). */

	for (i = 1; i < req_len - 2; ++i)

		checksum += byte_request[i];



	mutex_lock(&occ->occ_lock);



	/* Extract the seq_no from the command (first byte) */

	seq_no = *(const u8 *)request;

	rc = occ_putsram(occ, request, req_len);

	/*

	 * Get a sequence number and update the counter. Avoid a sequence

	 * number of 0 which would pass the response check below even if the

	 * OCC response is uninitialized. Any sequence number the user is

	 * trying to send is overwritten since this function is the only common

	 * interface to the OCC and therefore the only place we can guarantee

	 * unique sequence numbers.

	 */

	seq_no = occ->sequence_number++;

	if (!occ->sequence_number)

		occ->sequence_number = 1;

	checksum += seq_no;



	rc = occ_putsram(occ, request, req_len, seq_no, checksum);

	if (rc)

		goto done;
@@ -574,6 +593,7 @@ static int occ_probe(struct platform_device *pdev) 
	occ->version = (uintptr_t)of_device_get_match_data(dev);

	occ->dev = dev;

	occ->sbefifo = dev->parent;

	occ->sequence_number = 1;

	mutex_init(&occ->occ_lock);



	if (dev->of_node) {