[PATCH] net: bnxt_ptp: fix compilation error

The Broadcom bnxt_ptp driver does not compile with GCC 11.2.2 when
CONFIG_WERROR is enabled. The following error is generated:

drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.c: In function ‘bnxt_ptp_enable’:
drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.c:400:43: error: array
subscript 255 is above array bounds of ‘struct pps_pin[4]’
[-Werror=array-bounds]
  400 |  ptp->pps_info.pins[pin_id].event = BNXT_PPS_EVENT_EXTERNAL;
      |  ~~~~~~~~~~~~~~~~~~^~~~~~~~
In file included from drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.c:20:
drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.h:75:24: note: while
referencing ‘pins’
   75 |         struct pps_pin pins[BNXT_MAX_TSIO_PINS];
      |                        ^~~~
cc1: all warnings being treated as errors

This is due to the function ptp_find_pin() returning a pin ID of -1 when
a valid pin is not found and this error never being checked.
Change the TSIO_PIN_VALID() function to also check that a pin ID is not
negative and use this macro in bnxt_ptp_enable() to check the result of
the calls to ptp_find_pin() to fix this compilation error.

Fixes: 9e518f25802c ("bnxt_en: 1PPS functions to configure TSIO pins")
Cc: <redacted>
Signed-off-by: Damien Le Moal <redacted>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.c | 4 ++--
 drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.h | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.c
index a0b321a19361..3c8fccbb9013 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.c

@@ -390,7 +390,7 @@ static int bnxt_ptp_enable(struct ptp_clock_info *ptp_info,
 		/* Configure an External PPS IN */
 		pin_id = ptp_find_pin(ptp->ptp_clock, PTP_PF_EXTTS,
 				      rq->extts.index);
-		if (!on)
+		if (!on || !TSIO_PIN_VALID(pin_id))
 			break;
 		rc = bnxt_ptp_cfg_pin(bp, pin_id, BNXT_PPS_PIN_PPS_IN);
 		if (rc)

@@ -403,7 +403,7 @@ static int bnxt_ptp_enable(struct ptp_clock_info *ptp_info,
 		/* Configure a Periodic PPS OUT */
 		pin_id = ptp_find_pin(ptp->ptp_clock, PTP_PF_PEROUT,
 				      rq->perout.index);
-		if (!on)
+		if (!on || !TSIO_PIN_VALID(pin_id))
 			break;
 
 		rc = bnxt_ptp_cfg_pin(bp, pin_id, BNXT_PPS_PIN_PPS_OUT);

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.h b/drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.h
index 373baf45884b..530b9922608c 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.h
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.h

@@ -31,7 +31,7 @@ struct pps_pin {
 	u8 state;
 };
 
-#define TSIO_PIN_VALID(pin) ((pin) < (BNXT_MAX_TSIO_PINS))
+#define TSIO_PIN_VALID(pin) ((pin) >= 0 && (pin) < (BNXT_MAX_TSIO_PINS))
 
 #define EVENT_DATA2_PPS_EVENT_TYPE(data2)				\
 	((data2) & ASYNC_EVENT_CMPL_PPS_TIMESTAMP_EVENT_DATA2_EVENT_TYPE)

-- 
2.35.1