Merge branch 'Unlock-new-potential-in-SJA1105-with-PTP-system-timestamping'

Vladimir Oltean says:

====================
Unlock new potential in SJA1105 with PTP system timestamping

The SJA1105 being an automotive switch means it is designed to live in a
set-and-forget environment, far from the configure-at-runtime nature of
Linux. Frequently resetting the switch to change its static config means
it loses track of its PTP time, which is not good.

This patch series implements PTP system timestamping for this switch
(using the API introduced for SPI here:
https://www.mail-archive.com/netdev@vger.kernel.org/msg316725.html),
adding the following benefits to the driver:
- When under control of a user space PTP servo loop (ptp4l, phc2sys),
  the loss of sync during a switch reset is much more manageable, and
  the switch still remains in the s2 (locked servo) state.
- When synchronizing the switch using the software technique (based on
  reading clock A and writing the value to clock B, as opposed to
  relying on hardware timestamping), e.g. by using phc2sys, the sync
  accuracy is vastly improved due to the fact that the actual switch PTP
  time can now be more precisely correlated with something of better
  precision (CLOCK_REALTIME). The issue is that SPI transfers are
  inherently bad for measuring time with low jitter, but the newly
  introduced API aims to alleviate that issue somewhat.

This series is also a requirement for a future patch set that adds full
time-aware scheduling offload support for the switch.
====================

Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 177 insertions, 52 deletions

diff --git a/drivers/net/dsa/sja1105/sja1105.h b/drivers/net/dsa/sja1105/sja1105.h
index 91063ed3ef1b..64b3ee7b9771 100644
--- a/drivers/net/dsa/sja1105/sja1105.h
+++ b/drivers/net/dsa/sja1105/sja1105.h
@@ -122,9 +122,11 @@ int sja1105_xfer_buf(const struct sja1105_private *priv,
 		     sja1105_spi_rw_mode_t rw, u64 reg_addr,
 		     u8 *buf, size_t len);
 int sja1105_xfer_u32(const struct sja1105_private *priv,
-		     sja1105_spi_rw_mode_t rw, u64 reg_addr, u32 *value);
+		     sja1105_spi_rw_mode_t rw, u64 reg_addr, u32 *value,
+		     struct ptp_system_timestamp *ptp_sts);
 int sja1105_xfer_u64(const struct sja1105_private *priv,
-		     sja1105_spi_rw_mode_t rw, u64 reg_addr, u64 *value);
+		     sja1105_spi_rw_mode_t rw, u64 reg_addr, u64 *value,
+		     struct ptp_system_timestamp *ptp_sts);
 int sja1105_static_config_upload(struct sja1105_private *priv);
 int sja1105_inhibit_tx(const struct sja1105_private *priv,
 		       unsigned long port_bitmap, bool tx_inhibited);
diff --git a/drivers/net/dsa/sja1105/sja1105_main.c b/drivers/net/dsa/sja1105/sja1105_main.c
index d5dfda335aa1..475cc2d8b0e8 100644
--- a/drivers/net/dsa/sja1105/sja1105_main.c
+++ b/drivers/net/dsa/sja1105/sja1105_main.c
@@ -1349,9 +1349,17 @@ static void sja1105_bridge_leave(struct dsa_switch *ds, int port,
  */
 int sja1105_static_config_reload(struct sja1105_private *priv)
 {
+	struct ptp_system_timestamp ptp_sts_before;
+	struct ptp_system_timestamp ptp_sts_after;
 	struct sja1105_mac_config_entry *mac;
 	int speed_mbps[SJA1105_NUM_PORTS];
+	struct dsa_switch *ds = priv->ds;
+	s64 t1, t2, t3, t4;
+	s64 t12, t34;
 	int rc, i;
+	s64 now;
+
+	mutex_lock(&priv->mgmt_lock);
 
 	mac = priv->static_config.tables[BLK_IDX_MAC_CONFIG].entries;
 
@@ -1365,10 +1373,37 @@ int sja1105_static_config_reload(struct sja1105_private *priv)
 		mac[i].speed = SJA1105_SPEED_AUTO;
 	}
 
+	/* No PTP operations can run right now */
+	mutex_lock(&priv->ptp_data.lock);
+
+	rc = __sja1105_ptp_gettimex(ds, &now, &ptp_sts_before);
+	if (rc < 0)
+		goto out_unlock_ptp;
+
 	/* Reset switch and send updated static configuration */
 	rc = sja1105_static_config_upload(priv);
 	if (rc < 0)
-		goto out;
+		goto out_unlock_ptp;
+
+	rc = __sja1105_ptp_settime(ds, 0, &ptp_sts_after);
+	if (rc < 0)
+		goto out_unlock_ptp;
+
+	t1 = timespec64_to_ns(&ptp_sts_before.pre_ts);
+	t2 = timespec64_to_ns(&ptp_sts_before.post_ts);
+	t3 = timespec64_to_ns(&ptp_sts_after.pre_ts);
+	t4 = timespec64_to_ns(&ptp_sts_after.post_ts);
+	/* Mid point, corresponds to pre-reset PTPCLKVAL */
+	t12 = t1 + (t2 - t1) / 2;
+	/* Mid point, corresponds to post-reset PTPCLKVAL, aka 0 */
+	t34 = t3 + (t4 - t3) / 2;
+	/* Advance PTPCLKVAL by the time it took since its readout */
+	now += (t34 - t12);
+
+	__sja1105_ptp_adjtime(ds, now);
+
+out_unlock_ptp:
+	mutex_unlock(&priv->ptp_data.lock);
 
 	/* Configure the CGU (PLLs) for MII and RMII PHYs.
 	 * For these interfaces there is no dynamic configuration
@@ -1384,6 +1419,8 @@ int sja1105_static_config_reload(struct sja1105_private *priv)
 			goto out;
 	}
 out:
+	mutex_unlock(&priv->mgmt_lock);
+
 	return rc;
 }
 
@@ -1973,7 +2010,8 @@ static int sja1105_check_device_id(struct sja1105_private *priv)
 	u64 part_no;
 	int rc;
 
-	rc = sja1105_xfer_u32(priv, SPI_READ, regs->device_id, &device_id);
+	rc = sja1105_xfer_u32(priv, SPI_READ, regs->device_id, &device_id,
+			      NULL);
 	if (rc < 0)
 		return rc;
 
diff --git a/drivers/net/dsa/sja1105/sja1105_ptp.c b/drivers/net/dsa/sja1105/sja1105_ptp.c
index 783100397f8a..0a35813f9328 100644
--- a/drivers/net/dsa/sja1105/sja1105_ptp.c
+++ b/drivers/net/dsa/sja1105/sja1105_ptp.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (c) 2019, Vladimir Oltean <olteanv@gmail.com>
  */
+#include <linux/spi/spi.h>
 #include "sja1105.h"
 
 /* The adjfine API clamps ppb between [-32,768,000, 32,768,000], and
@@ -335,19 +336,23 @@ static int sja1105_ptpegr_ts_poll(struct dsa_switch *ds, int port, u64 *ts)
 }
 
 /* Caller must hold ptp_data->lock */
-static int sja1105_ptpclkval_read(struct sja1105_private *priv, u64 *ticks)
+static int sja1105_ptpclkval_read(struct sja1105_private *priv, u64 *ticks,
+				  struct ptp_system_timestamp *ptp_sts)
 {
 	const struct sja1105_regs *regs = priv->info->regs;
 
-	return sja1105_xfer_u64(priv, SPI_READ, regs->ptpclkval, ticks);
+	return sja1105_xfer_u64(priv, SPI_READ, regs->ptpclkval, ticks,
+				ptp_sts);
 }
 
 /* Caller must hold ptp_data->lock */
-static int sja1105_ptpclkval_write(struct sja1105_private *priv, u64 ticks)
+static int sja1105_ptpclkval_write(struct sja1105_private *priv, u64 ticks,
+				   struct ptp_system_timestamp *ptp_sts)
 {
 	const struct sja1105_regs *regs = priv->info->regs;
 
-	return sja1105_xfer_u64(priv, SPI_WRITE, regs->ptpclkval, &ticks);
+	return sja1105_xfer_u64(priv, SPI_WRITE, regs->ptpclkval, &ticks,
+				ptp_sts);
 }
 
 #define rxtstamp_to_tagger(d) \
@@ -370,7 +375,7 @@ static void sja1105_rxtstamp_work(struct work_struct *work)
 		u64 ticks, ts;
 		int rc;
 
-		rc = sja1105_ptpclkval_read(priv, &ticks);
+		rc = sja1105_ptpclkval_read(priv, &ticks, NULL);
 		if (rc < 0) {
 			dev_err(ds->dev, "Failed to read PTP clock: %d\n", rc);
 			kfree_skb(skb);
@@ -423,7 +428,7 @@ bool sja1105_port_txtstamp(struct dsa_switch *ds, int port,
 	return true;
 }
 
-int sja1105_ptp_reset(struct dsa_switch *ds)
+static int sja1105_ptp_reset(struct dsa_switch *ds)
 {
 	struct sja1105_private *priv = ds->priv;
 	struct sja1105_ptp_data *ptp_data = &priv->ptp_data;
@@ -441,18 +446,38 @@ int sja1105_ptp_reset(struct dsa_switch *ds)
 	return rc;
 }
 
-static int sja1105_ptp_gettime(struct ptp_clock_info *ptp,
-			       struct timespec64 *ts)
+/* Caller must hold ptp_data->lock */
+int __sja1105_ptp_gettimex(struct dsa_switch *ds, u64 *ns,
+			   struct ptp_system_timestamp *ptp_sts)
+{
+	struct sja1105_private *priv = ds->priv;
+	u64 ticks;
+	int rc;
+
+	rc = sja1105_ptpclkval_read(priv, &ticks, ptp_sts);
+	if (rc < 0) {
+		dev_err(ds->dev, "Failed to read PTP clock: %d\n", rc);
+		return rc;
+	}
+
+	*ns = sja1105_ticks_to_ns(ticks);
+
+	return 0;
+}
+
+static int sja1105_ptp_gettimex(struct ptp_clock_info *ptp,
+				struct timespec64 *ts,
+				struct ptp_system_timestamp *ptp_sts)
 {
 	struct sja1105_ptp_data *ptp_data = ptp_caps_to_data(ptp);
 	struct sja1105_private *priv = ptp_data_to_sja1105(ptp_data);
-	u64 ticks = 0;
+	u64 now = 0;
 	int rc;
 
 	mutex_lock(&ptp_data->lock);
 
-	rc = sja1105_ptpclkval_read(priv, &ticks);
-	*ts = ns_to_timespec64(sja1105_ticks_to_ns(ticks));
+	rc = __sja1105_ptp_gettimex(priv->ds, &now, ptp_sts);
+	*ts = ns_to_timespec64(now);
 
 	mutex_unlock(&ptp_data->lock);
 
@@ -474,24 +499,34 @@ static int sja1105_ptp_mode_set(struct sja1105_private *priv,
 }
 
 /* Write to PTPCLKVAL while PTPCLKADD is 0 */
+int __sja1105_ptp_settime(struct dsa_switch *ds, u64 ns,
+			  struct ptp_system_timestamp *ptp_sts)
+{
+	struct sja1105_private *priv = ds->priv;
+	u64 ticks = ns_to_sja1105_ticks(ns);
+	int rc;
+
+	rc = sja1105_ptp_mode_set(priv, PTP_SET_MODE);
+	if (rc < 0) {
+		dev_err(priv->ds->dev, "Failed to put PTPCLK in set mode\n");
+		return rc;
+	}
+
+	return sja1105_ptpclkval_write(priv, ticks, ptp_sts);
+}
+
 static int sja1105_ptp_settime(struct ptp_clock_info *ptp,
 			       const struct timespec64 *ts)
 {
 	struct sja1105_ptp_data *ptp_data = ptp_caps_to_data(ptp);
 	struct sja1105_private *priv = ptp_data_to_sja1105(ptp_data);
-	u64 ticks = ns_to_sja1105_ticks(timespec64_to_ns(ts));
+	u64 ns = timespec64_to_ns(ts);
 	int rc;
 
 	mutex_lock(&ptp_data->lock);
 
-	rc = sja1105_ptp_mode_set(priv, PTP_SET_MODE);
-	if (rc < 0) {
-		dev_err(priv->ds->dev, "Failed to put PTPCLK in set mode\n");
-		goto out;
-	}
+	rc = __sja1105_ptp_settime(priv->ds, ns, NULL);
 
-	rc = sja1105_ptpclkval_write(priv, ticks);
-out:
 	mutex_unlock(&ptp_data->lock);
 
 	return rc;
@@ -516,7 +551,8 @@ static int sja1105_ptp_adjfine(struct ptp_clock_info *ptp, long scaled_ppm)
 
 	mutex_lock(&ptp_data->lock);
 
-	rc = sja1105_xfer_u32(priv, SPI_WRITE, regs->ptpclkrate, &clkrate32);
+	rc = sja1105_xfer_u32(priv, SPI_WRITE, regs->ptpclkrate, &clkrate32,
+			      NULL);
 
 	mutex_unlock(&ptp_data->lock);
 
@@ -524,24 +560,31 @@ static int sja1105_ptp_adjfine(struct ptp_clock_info *ptp, long scaled_ppm)
 }
 
 /* Write to PTPCLKVAL while PTPCLKADD is 1 */
-static int sja1105_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
+int __sja1105_ptp_adjtime(struct dsa_switch *ds, s64 delta)
 {
-	struct sja1105_ptp_data *ptp_data = ptp_caps_to_data(ptp);
-	struct sja1105_private *priv = ptp_data_to_sja1105(ptp_data);
+	struct sja1105_private *priv = ds->priv;
 	s64 ticks = ns_to_sja1105_ticks(delta);
 	int rc;
 
-	mutex_lock(&ptp_data->lock);
-
 	rc = sja1105_ptp_mode_set(priv, PTP_ADD_MODE);
 	if (rc < 0) {
 		dev_err(priv->ds->dev, "Failed to put PTPCLK in add mode\n");
-		goto out;
+		return rc;
 	}
 
-	rc = sja1105_ptpclkval_write(priv, ticks);
+	return sja1105_ptpclkval_write(priv, ticks, NULL);
+}
+
+static int sja1105_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
+{
+	struct sja1105_ptp_data *ptp_data = ptp_caps_to_data(ptp);
+	struct sja1105_private *priv = ptp_data_to_sja1105(ptp_data);
+	int rc;
+
+	mutex_lock(&ptp_data->lock);
+
+	rc = __sja1105_ptp_adjtime(priv->ds, delta);
 
-out:
 	mutex_unlock(&ptp_data->lock);
 
 	return rc;
@@ -558,7 +601,7 @@ int sja1105_ptp_clock_register(struct dsa_switch *ds)
 		.name		= "SJA1105 PHC",
 		.adjfine	= sja1105_ptp_adjfine,
 		.adjtime	= sja1105_ptp_adjtime,
-		.gettime64	= sja1105_ptp_gettime,
+		.gettimex64	= sja1105_ptp_gettimex,
 		.settime64	= sja1105_ptp_settime,
 		.max_adj	= SJA1105_MAX_ADJ_PPB,
 	};
@@ -604,7 +647,7 @@ void sja1105_ptp_txtstamp_skb(struct dsa_switch *ds, int slot,
 
 	mutex_lock(&ptp_data->lock);
 
-	rc = sja1105_ptpclkval_read(priv, &ticks);
+	rc = sja1105_ptpclkval_read(priv, &ticks, NULL);
 	if (rc < 0) {
 		dev_err(ds->dev, "Failed to read PTP clock: %d\n", rc);
 		kfree_skb(skb);
diff --git a/drivers/net/dsa/sja1105/sja1105_ptp.h b/drivers/net/dsa/sja1105/sja1105_ptp.h
index 243f130374d2..19e707db7e8c 100644
--- a/drivers/net/dsa/sja1105/sja1105_ptp.h
+++ b/drivers/net/dsa/sja1105/sja1105_ptp.h
@@ -51,8 +51,6 @@ int sja1105_get_ts_info(struct dsa_switch *ds, int port,
 void sja1105_ptp_txtstamp_skb(struct dsa_switch *ds, int slot,
 			      struct sk_buff *clone);
 
-int sja1105_ptp_reset(struct dsa_switch *ds);
-
 bool sja1105_port_rxtstamp(struct dsa_switch *ds, int port,
 			   struct sk_buff *skb, unsigned int type);
 
@@ -63,6 +61,14 @@ int sja1105_hwtstamp_get(struct dsa_switch *ds, int port, struct ifreq *ifr);
 
 int sja1105_hwtstamp_set(struct dsa_switch *ds, int port, struct ifreq *ifr);
 
+int __sja1105_ptp_gettimex(struct dsa_switch *ds, u64 *ns,
+			   struct ptp_system_timestamp *sts);
+
+int __sja1105_ptp_settime(struct dsa_switch *ds, u64 ns,
+			  struct ptp_system_timestamp *ptp_sts);
+
+int __sja1105_ptp_adjtime(struct dsa_switch *ds, s64 delta);
+
 #else
 
 struct sja1105_ptp_cmd;
@@ -87,7 +93,19 @@ static inline void sja1105_ptp_txtstamp_skb(struct dsa_switch *ds, int slot,
 {
 }
 
-static inline int sja1105_ptp_reset(struct dsa_switch *ds)
+static inline int __sja1105_ptp_gettimex(struct dsa_switch *ds, u64 *ns,
+					 struct ptp_system_timestamp *sts)
+{
+	return 0;
+}
+
+static inline int __sja1105_ptp_settime(struct dsa_switch *ds, u64 ns,
+					struct ptp_system_timestamp *ptp_sts)
+{
+	return 0;
+}
+
+static inline int __sja1105_ptp_adjtime(struct dsa_switch *ds, s64 delta)
 {
 	return 0;
 }
diff --git a/drivers/net/dsa/sja1105/sja1105_spi.c b/drivers/net/dsa/sja1105/sja1105_spi.c
index ed02410a9366..cb48e77f63fd 100644
--- a/drivers/net/dsa/sja1105/sja1105_spi.c
+++ b/drivers/net/dsa/sja1105/sja1105_spi.c
@@ -42,9 +42,9 @@ sja1105_spi_message_pack(void *buf, const struct sja1105_spi_message *msg)
  * - SPI_READ:  creates and sends an SPI read message from absolute
  *		address reg_addr, writing @len bytes into *buf
  */
-int sja1105_xfer_buf(const struct sja1105_private *priv,
-		     sja1105_spi_rw_mode_t rw, u64 reg_addr,
-		     u8 *buf, size_t len)
+static int sja1105_xfer(const struct sja1105_private *priv,
+			sja1105_spi_rw_mode_t rw, u64 reg_addr, u8 *buf,
+			size_t len, struct ptp_system_timestamp *ptp_sts)
 {
 	struct sja1105_chunk chunk = {
 		.len = min_t(size_t, len, SJA1105_SIZE_SPI_MSG_MAXLEN),
@@ -81,6 +81,7 @@ int sja1105_xfer_buf(const struct sja1105_private *priv,
 		struct spi_transfer *chunk_xfer = sja1105_chunk_xfer(xfers, i);
 		struct spi_transfer *hdr_xfer = sja1105_hdr_xfer(xfers, i);
 		u8 *hdr_buf = sja1105_hdr_buf(hdr_bufs, i);
+		struct spi_transfer *ptp_sts_xfer;
 		struct sja1105_spi_message msg;
 
 		/* Populate the transfer's header buffer */
@@ -102,6 +103,26 @@ int sja1105_xfer_buf(const struct sja1105_private *priv,
 			chunk_xfer->tx_buf = chunk.buf;
 		chunk_xfer->len = chunk.len;
 
+		/* Request timestamping for the transfer. Instead of letting
+		 * callers specify which byte they want to timestamp, we can
+		 * make certain assumptions:
+		 * - A read operation will request a software timestamp when
+		 *   what's being read is the PTP time. That is snapshotted by
+		 *   the switch hardware at the end of the command portion
+		 *   (hdr_xfer).
+		 * - A write operation will request a software timestamp on
+		 *   actions that modify the PTP time. Taking clock stepping as
+		 *   an example, the switch writes the PTP time at the end of
+		 *   the data portion (chunk_xfer).
+		 */
+		if (rw == SPI_READ)
+			ptp_sts_xfer = hdr_xfer;
+		else
+			ptp_sts_xfer = chunk_xfer;
+		ptp_sts_xfer->ptp_sts_word_pre = ptp_sts_xfer->len - 1;
+		ptp_sts_xfer->ptp_sts_word_post = ptp_sts_xfer->len - 1;
+		ptp_sts_xfer->ptp_sts = ptp_sts;
+
 		/* Calculate next chunk */
 		chunk.buf += chunk.len;
 		chunk.reg_addr += chunk.len / 4;
@@ -123,6 +144,13 @@ int sja1105_xfer_buf(const struct sja1105_private *priv,
 	return rc;
 }
 
+int sja1105_xfer_buf(const struct sja1105_private *priv,
+		     sja1105_spi_rw_mode_t rw, u64 reg_addr,
+		     u8 *buf, size_t len)
+{
+	return sja1105_xfer(priv, rw, reg_addr, buf, len, NULL);
+}
+
 /* If @rw is:
  * - SPI_WRITE: creates and sends an SPI write message at absolute
  *		address reg_addr
@@ -133,7 +161,8 @@ int sja1105_xfer_buf(const struct sja1105_private *priv,
  * CPU endianness and directly usable by software running on the core.
  */
 int sja1105_xfer_u64(const struct sja1105_private *priv,
-		     sja1105_spi_rw_mode_t rw, u64 reg_addr, u64 *value)
+		     sja1105_spi_rw_mode_t rw, u64 reg_addr, u64 *value,
+		     struct ptp_system_timestamp *ptp_sts)
 {
 	u8 packed_buf[8];
 	int rc;
@@ -141,7 +170,7 @@ int sja1105_xfer_u64(const struct sja1105_private *priv,
 	if (rw == SPI_WRITE)
 		sja1105_pack(packed_buf, value, 63, 0, 8);
 
-	rc = sja1105_xfer_buf(priv, rw, reg_addr, packed_buf, 8);
+	rc = sja1105_xfer(priv, rw, reg_addr, packed_buf, 8, ptp_sts);
 
 	if (rw == SPI_READ)
 		sja1105_unpack(packed_buf, value, 63, 0, 8);
@@ -151,7 +180,8 @@ int sja1105_xfer_u64(const struct sja1105_private *priv,
 
 /* Same as above, but transfers only a 4 byte word */
 int sja1105_xfer_u32(const struct sja1105_private *priv,
-		     sja1105_spi_rw_mode_t rw, u64 reg_addr, u32 *value)
+		     sja1105_spi_rw_mode_t rw, u64 reg_addr, u32 *value,
+		     struct ptp_system_timestamp *ptp_sts)
 {
 	u8 packed_buf[4];
 	u64 tmp;
@@ -165,7 +195,7 @@ int sja1105_xfer_u32(const struct sja1105_private *priv,
 		sja1105_pack(packed_buf, &tmp, 31, 0, 4);
 	}
 
-	rc = sja1105_xfer_buf(priv, rw, reg_addr, packed_buf, 4);
+	rc = sja1105_xfer(priv, rw, reg_addr, packed_buf, 4, ptp_sts);
 
 	if (rw == SPI_READ) {
 		sja1105_unpack(packed_buf, &tmp, 31, 0, 4);
@@ -293,7 +323,7 @@ int sja1105_inhibit_tx(const struct sja1105_private *priv,
 	int rc;
 
 	rc = sja1105_xfer_u32(priv, SPI_READ, regs->port_control,
-			      &inhibit_cmd);
+			      &inhibit_cmd, NULL);
 	if (rc < 0)
 		return rc;
 
@@ -303,7 +333,7 @@ int sja1105_inhibit_tx(const struct sja1105_private *priv,
 		inhibit_cmd &= ~port_bitmap;
 
 	return sja1105_xfer_u32(priv, SPI_WRITE, regs->port_control,
-				&inhibit_cmd);
+				&inhibit_cmd, NULL);
 }
 
 struct sja1105_status {
@@ -481,12 +511,6 @@ int sja1105_static_config_upload(struct sja1105_private *priv)
 		dev_info(dev, "Succeeded after %d tried\n", RETRIES - retries);
 	}
 
-	rc = sja1105_ptp_reset(priv->ds);
-	if (rc < 0)
-		dev_err(dev, "Failed to reset PTP clock: %d\n", rc);
-
-	dev_info(dev, "Reset switch and programmed static config\n");
-
 out:
 	kfree(config_buf);
 	return rc;