Commit eb9fa77a authored by Peter Fink's avatar Peter Fink Committed by Marc Kleine-Budde
Browse files

can: gs_usb: add usb quirk for NXP LPC546xx controllers 

Introduce a workaround for a NXP chip errata on LPC546xx
controllers (Errata sheet LPC546xx / USB.15).

According to the document corruption can occur when the following
conditions are met:
* A TX (IN) transfer happens after a RX (OUT) transfer.
* The RX (OUT) transfer length is 4 + N * 16 (N >= 0) bytes.

Even though the struct gs_host_frame has a size of 76 bytes for a FD
frame, which does not apply to the above rule, corruption could be
seen.

Adding a dummy byte to break the second condition also on transfer
lengths with 4 + N * 8 bytes reliably circumvents USB transfer data
corruption.

The firmware can now request this quirk by setting
GS_CAN_FEATURE_REQ_USB_QUIRK_LPC546XX.

Link: https://lore.kernel.org/all/20220309124132.291861-17-mkl@pengutronix.de


Signed-off-by: default avatarPeter Fink <pfink@christ-es.de>
Signed-off-by: default avatarChristoph Möhring <cmoehring@christ-es.de>
Signed-off-by: default avatarAlexander Schartner <aschartner@christ-es.de>
Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
parent 26949ac9

drivers/net/can/usb/gs_usb.c

+27 −2
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 
 * Many thanks to all socketcan devs!

 */



#include <linux/bitfield.h>

#include <linux/ethtool.h>

#include <linux/init.h>

#include <linux/module.h>
@@ -100,6 +101,7 @@ struct gs_device_config { 
/* GS_CAN_FEATURE_USER_ID BIT(6) */

#define GS_CAN_MODE_PAD_PKTS_TO_MAX_PKT_SIZE BIT(7)

#define GS_CAN_MODE_FD BIT(8)

/* GS_CAN_FEATURE_REQ_USB_QUIRK_LPC546XX BIT(9) */



struct gs_device_mode {

	__le32 mode;
@@ -133,6 +135,8 @@ struct gs_identify_mode { 
#define GS_CAN_FEATURE_USER_ID BIT(6)

#define GS_CAN_FEATURE_PAD_PKTS_TO_MAX_PKT_SIZE BIT(7)

#define GS_CAN_FEATURE_FD BIT(8)

#define GS_CAN_FEATURE_REQ_USB_QUIRK_LPC546XX BIT(9)

#define GS_CAN_FEATURE_MASK GENMASK(9, 0)



struct gs_device_bt_const {

	__le32 feature;
@@ -156,10 +160,20 @@ struct classic_can { 
	u8 data[8];

} __packed;



struct classic_can_quirk {

	u8 data[8];

	u8 quirk;

} __packed;



struct canfd {

	u8 data[64];

} __packed;



struct canfd_quirk {

	u8 data[64];

	u8 quirk;

} __packed;



struct gs_host_frame {

	u32 echo_id;

	__le32 can_id;
@@ -171,7 +185,9 @@ struct gs_host_frame { 


	union {

		DECLARE_FLEX_ARRAY(struct classic_can, classic_can);

		DECLARE_FLEX_ARRAY(struct classic_can_quirk, classic_can_quirk);

		DECLARE_FLEX_ARRAY(struct canfd, canfd);

		DECLARE_FLEX_ARRAY(struct canfd_quirk, canfd_quirk);

	};

} __packed;

/* The GS USB devices make use of the same flags and masks as in
@@ -204,6 +220,7 @@ struct gs_can { 
	struct can_bittiming_const bt_const;

	unsigned int channel;	/* channel number */



	u32 feature;

	unsigned int hf_size_tx;



	/* This lock prevents a race condition between xmit and receive. */
@@ -666,8 +683,15 @@ static int gs_can_open(struct net_device *netdev) 
	ctrlmode = dev->can.ctrlmode;

	if (ctrlmode & CAN_CTRLMODE_FD) {

		flags |= GS_CAN_MODE_FD;



		if (dev->feature & GS_CAN_FEATURE_REQ_USB_QUIRK_LPC546XX)

			dev->hf_size_tx = struct_size(hf, canfd_quirk, 1);

		else

			dev->hf_size_tx = struct_size(hf, canfd, 1);

	} else {

		if (dev->feature & GS_CAN_FEATURE_REQ_USB_QUIRK_LPC546XX)

			dev->hf_size_tx = struct_size(hf, classic_can_quirk, 1);

		else

			dev->hf_size_tx = struct_size(hf, classic_can, 1);

	}
@@ -938,6 +962,7 @@ static struct gs_can *gs_make_candev(unsigned int channel, 
	dev->can.ctrlmode_supported = CAN_CTRLMODE_CC_LEN8_DLC;



	feature = le32_to_cpu(bt_const->feature);

	dev->feature = FIELD_GET(GS_CAN_FEATURE_MASK, feature);

	if (feature & GS_CAN_FEATURE_LISTEN_ONLY)

		dev->can.ctrlmode_supported |= CAN_CTRLMODE_LISTENONLY;