[PATCH v2 0/3] OCC: fsi and hwmon: Set sequence number in submit interface

[PATCH v2 0/3] OCC: fsi and hwmon: Set sequence number in submit interface

[Eddie James]

Conflicting sequence numbers have resulted in users of the OCC interface
getting the wrong response. For example, both the hwmon driver and an
application might send a transfer near the same time with the same sequence
number, and then one or both will get an incorrect respnse, but cannot tell
because the sequence number looks correct.
Perform the sequence numbering in the submit interface to make sure each
transfer has a unique sequence number. This also requires that the submit
interface perform the checksum calculation for the command. Adjust the hwmon
driver accordingly too.

Changes since v1:
 - fix 0day warnings and errors.

Eddie James (3):
  fsi: occ: Force sequence numbering per OCC
  hwmon: (occ) Remove sequence numbering and checksum calculation
  fsi: occ: Add dynamic debug to dump command and response

 drivers/fsi/fsi-occ.c      | 99 +++++++++++++++++++++++++++++++-------
 drivers/hwmon/occ/common.c | 30 +++++-------
 drivers/hwmon/occ/common.h |  3 +-
 drivers/hwmon/occ/p8_i2c.c | 15 +++---
 drivers/hwmon/occ/p9_sbe.c |  4 +-
 5 files changed, 106 insertions(+), 45 deletions(-)

-- 
2.27.0

[PATCH v2 1/3] fsi: occ: Force sequence numbering per OCC

[Eddie James]

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: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
---
 drivers/fsi/fsi-occ.c | 54 +++++++++++++++++++++++++++++--------------
 1 file changed, 37 insertions(+), 17 deletions(-)

diff --git a/drivers/fsi/fsi-occ.c b/drivers/fsi/fsi-occ.c
index b223f0ef337b..ecf738411fe2 100644
--- a/drivers/fsi/fsi-occ.c
+++ b/drivers/fsi/fsi-occ.c
@@ -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) {
-- 
2.27.0

[PATCH v2 2/3] hwmon: (occ) Remove sequence numbering and checksum calculation

[Eddie James]

Checksumming of the request and sequence numbering is now done in the
OCC interface driver in order to keep unique sequence numbers. So
remove those in the hwmon driver. Also, add the command length to the
send_cmd function pointer, since the checksum must be placed in the
last two bytes of the command. The submit interface must receive the
exact size of the command - previously it could be rounded to the
nearest 8 bytes with no consequence.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
---
Changes since v1:
 - Use min_t to avoid type comparison warnings with some platforms/configs

 drivers/hwmon/occ/common.c | 30 ++++++++++++------------------
 drivers/hwmon/occ/common.h |  3 +--
 drivers/hwmon/occ/p8_i2c.c | 15 +++++++++------
 drivers/hwmon/occ/p9_sbe.c |  4 ++--
 4 files changed, 24 insertions(+), 28 deletions(-)

diff --git a/drivers/hwmon/occ/common.c b/drivers/hwmon/occ/common.c
index 0d68a78be980..fc298268c89e 100644
--- a/drivers/hwmon/occ/common.c
+++ b/drivers/hwmon/occ/common.c
@@ -132,22 +132,20 @@ struct extended_sensor {
 static int occ_poll(struct occ *occ)
 {
 	int rc;
-	u16 checksum = occ->poll_cmd_data + occ->seq_no + 1;
-	u8 cmd[8];
+	u8 cmd[7];
 	struct occ_poll_response_header *header;
 
 	/* big endian */
-	cmd[0] = occ->seq_no++;		/* sequence number */
+	cmd[0] = 0;			/* sequence number */
 	cmd[1] = 0;			/* cmd type */
 	cmd[2] = 0;			/* data length msb */
 	cmd[3] = 1;			/* data length lsb */
 	cmd[4] = occ->poll_cmd_data;	/* data */
-	cmd[5] = checksum >> 8;		/* checksum msb */
-	cmd[6] = checksum & 0xFF;	/* checksum lsb */
-	cmd[7] = 0;
+	cmd[5] = 0;			/* checksum msb */
+	cmd[6] = 0;			/* checksum lsb */
 
 	/* mutex should already be locked if necessary */
-	rc = occ->send_cmd(occ, cmd);
+	rc = occ->send_cmd(occ, cmd, sizeof(cmd));
 	if (rc) {
 		occ->last_error = rc;
 		if (occ->error_count++ > OCC_ERROR_COUNT_THRESHOLD)
@@ -184,25 +182,23 @@ static int occ_set_user_power_cap(struct occ *occ, u16 user_power_cap)
 {
 	int rc;
 	u8 cmd[8];
-	u16 checksum = 0x24;
 	__be16 user_power_cap_be = cpu_to_be16(user_power_cap);
 
-	cmd[0] = 0;
-	cmd[1] = 0x22;
-	cmd[2] = 0;
-	cmd[3] = 2;
+	cmd[0] = 0;	/* sequence number */
+	cmd[1] = 0x22;	/* cmd type */
+	cmd[2] = 0;	/* data length msb */
+	cmd[3] = 2;	/* data length lsb */
 
 	memcpy(&cmd[4], &user_power_cap_be, 2);
 
-	checksum += cmd[4] + cmd[5];
-	cmd[6] = checksum >> 8;
-	cmd[7] = checksum & 0xFF;
+	cmd[6] = 0;	/* checksum msb */
+	cmd[7] = 0;	/* checksum lsb */
 
 	rc = mutex_lock_interruptible(&occ->lock);
 	if (rc)
 		return rc;
 
-	rc = occ->send_cmd(occ, cmd);
+	rc = occ->send_cmd(occ, cmd, sizeof(cmd));
 
 	mutex_unlock(&occ->lock);
 
@@ -1151,8 +1147,6 @@ int occ_setup(struct occ *occ, const char *name)
 {
 	int rc;
 
-	/* start with 1 to avoid false match with zero-initialized SRAM buffer */
-	occ->seq_no = 1;
 	mutex_init(&occ->lock);
 	occ->groups[0] = &occ->group;
 
diff --git a/drivers/hwmon/occ/common.h b/drivers/hwmon/occ/common.h
index e6df719770e8..5020117be740 100644
--- a/drivers/hwmon/occ/common.h
+++ b/drivers/hwmon/occ/common.h
@@ -95,9 +95,8 @@ struct occ {
 	struct occ_sensors sensors;
 
 	int powr_sample_time_us;	/* average power sample time */
-	u8 seq_no;
 	u8 poll_cmd_data;		/* to perform OCC poll command */
-	int (*send_cmd)(struct occ *occ, u8 *cmd);
+	int (*send_cmd)(struct occ *occ, u8 *cmd, size_t len);
 
 	unsigned long next_update;
 	struct mutex lock;		/* lock OCC access */
diff --git a/drivers/hwmon/occ/p8_i2c.c b/drivers/hwmon/occ/p8_i2c.c
index 0cf8588be35a..9e61e1fb5142 100644
--- a/drivers/hwmon/occ/p8_i2c.c
+++ b/drivers/hwmon/occ/p8_i2c.c
@@ -97,18 +97,21 @@ static int p8_i2c_occ_putscom_u32(struct i2c_client *client, u32 address,
 }
 
 static int p8_i2c_occ_putscom_be(struct i2c_client *client, u32 address,
-				 u8 *data)
+				 u8 *data, size_t len)
 {
-	__be32 data0, data1;
+	__be32 data0 = 0, data1 = 0;
 
-	memcpy(&data0, data, 4);
-	memcpy(&data1, data + 4, 4);
+	memcpy(&data0, data, min_t(size_t, len, 4));
+	if (len > 4) {
+		len -= 4;
+		memcpy(&data1, data + 4, min_t(size_t, len, 4));
+	}
 
 	return p8_i2c_occ_putscom_u32(client, address, be32_to_cpu(data0),
 				      be32_to_cpu(data1));
 }
 
-static int p8_i2c_occ_send_cmd(struct occ *occ, u8 *cmd)
+static int p8_i2c_occ_send_cmd(struct occ *occ, u8 *cmd, size_t len)
 {
 	int i, rc;
 	unsigned long start;
@@ -127,7 +130,7 @@ static int p8_i2c_occ_send_cmd(struct occ *occ, u8 *cmd)
 		return rc;
 
 	/* write command (expected to already be BE), we need bus-endian... */
-	rc = p8_i2c_occ_putscom_be(client, OCB_DATA3, cmd);
+	rc = p8_i2c_occ_putscom_be(client, OCB_DATA3, cmd, len);
 	if (rc)
 		return rc;
 
diff --git a/drivers/hwmon/occ/p9_sbe.c b/drivers/hwmon/occ/p9_sbe.c
index f6387cc0b754..9709f2b9c052 100644
--- a/drivers/hwmon/occ/p9_sbe.c
+++ b/drivers/hwmon/occ/p9_sbe.c
@@ -16,14 +16,14 @@ struct p9_sbe_occ {
 
 #define to_p9_sbe_occ(x)	container_of((x), struct p9_sbe_occ, occ)
 
-static int p9_sbe_occ_send_cmd(struct occ *occ, u8 *cmd)
+static int p9_sbe_occ_send_cmd(struct occ *occ, u8 *cmd, size_t len)
 {
 	struct occ_response *resp = &occ->resp;
 	struct p9_sbe_occ *ctx = to_p9_sbe_occ(occ);
 	size_t resp_len = sizeof(*resp);
 	int rc;
 
-	rc = fsi_occ_submit(ctx->sbe, cmd, 8, resp, &resp_len);
+	rc = fsi_occ_submit(ctx->sbe, cmd, len, resp, &resp_len);
 	if (rc < 0)
 		return rc;
 
-- 
2.27.0

[PATCH v2 3/3] fsi: occ: Add dynamic debug to dump command and response

[Eddie James]

Use the dynamic branching capability of the dynamic debug subsystem
to dump the command and response with the correct OCC device name.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
---
Changes since v1:
 - include dynamic_debug to make sure the dynamic branching stuff is
   included on all platforms/configs

 drivers/fsi/fsi-occ.c | 45 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/drivers/fsi/fsi-occ.c b/drivers/fsi/fsi-occ.c
index ecf738411fe2..2bc53ea8f54f 100644
--- a/drivers/fsi/fsi-occ.c
+++ b/drivers/fsi/fsi-occ.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 
 #include <linux/device.h>
+#include <linux/dynamic_debug.h>
 #include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/fs.h>
@@ -21,6 +22,15 @@
 #include <linux/uaccess.h>
 #include <asm/unaligned.h>
 
+#if !defined(CONFIG_DYNAMIC_DEBUG_CORE)
+#define DEFINE_DYNAMIC_DEBUG_METADATA(name, fmt)
+#if defined(DEBUG)
+#define DYNAMIC_DEBUG_BRANCH(descriptor) true
+#else /* DEBUG */
+#define DYNAMIC_DEBUG_BRANCH(descriptor) false
+#endif /* DEBUG */
+#endif /* CONFIG_DYNAMIC_DEBUG_CORE */
+
 #define OCC_SRAM_BYTES		4096
 #define OCC_CMD_DATA_BYTES	4090
 #define OCC_RESP_DATA_BYTES	4089
@@ -359,6 +369,20 @@ static int occ_putsram(struct occ *occ, const void *data, ssize_t len,
 	byte_buf[len - 2] = checksum >> 8;
 	byte_buf[len - 1] = checksum & 0xff;
 
+	{
+		DEFINE_DYNAMIC_DEBUG_METADATA(ddm_occ_cmd, "OCC command");
+
+		if (DYNAMIC_DEBUG_BRANCH(ddm_occ_cmd)) {
+			char prefix[64];
+
+			snprintf(prefix, sizeof(prefix), "%s %s: cmd ",
+				 dev_driver_string(occ->dev),
+				 dev_name(occ->dev));
+			print_hex_dump(KERN_DEBUG, prefix, DUMP_PREFIX_OFFSET,
+				       16, 4, byte_buf, len, false);
+		}
+	}
+
 	rc = sbefifo_submit(occ->sbefifo, buf, cmd_len, buf, &resp_len);
 	if (rc)
 		goto free;
@@ -556,6 +580,27 @@ int fsi_occ_submit(struct device *dev, const void *request, size_t req_len,
 	}
 
 	*resp_len = resp_data_length + 7;
+
+	{
+		DEFINE_DYNAMIC_DEBUG_METADATA(ddm_occ_rsp,
+					      "OCC response");
+		DEFINE_DYNAMIC_DEBUG_METADATA(ddm_occ_full_rsp,
+					      "OCC full response");
+
+		if (DYNAMIC_DEBUG_BRANCH(ddm_occ_full_rsp) ||
+		    DYNAMIC_DEBUG_BRANCH(ddm_occ_rsp)) {
+			char prefix[64];
+			size_t l = DYNAMIC_DEBUG_BRANCH(ddm_occ_full_rsp) ?
+				*resp_len : 16;
+
+			snprintf(prefix, sizeof(prefix), "%s %s: rsp ",
+				 dev_driver_string(occ->dev),
+				 dev_name(occ->dev));
+			print_hex_dump(KERN_DEBUG, prefix, DUMP_PREFIX_OFFSET,
+				       16, 4, resp, l, false);
+		}
+	}
+
 	rc = occ_verify_checksum(occ, resp, resp_data_length);
 
  done:
-- 
2.27.0