RE: [PATCH 04/22] NTB: Add messaging NTB API

From: Allen Hubbe
Date: Sat Dec 03 2016 - 19:11:01 EST

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From: Serge Semin
> IDT PCIe-switches have message registers to communicate with peer devices.
> This patch adds new NTB API callback methods, which can be used to utilize
> these registers functionality.
>

Please split: add msg api; make spads optional.

See comments below on ntb_dev_ops_is_valid.

> Signed-off-by: Serge Semin <fancer.lancer@xxxxxxxxx>
>
> ---
> drivers/ntb/ntb.c | 13 +++
> include/linux/ntb.h | 236 ++++++++++++++++++++++++++++++++++++++++++++++++++--
> 2 files changed, 241 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/ntb/ntb.c b/drivers/ntb/ntb.c
> index 2e25307..4b2cc60 100644
> --- a/drivers/ntb/ntb.c
> +++ b/drivers/ntb/ntb.c
> @@ -191,6 +191,19 @@ void ntb_db_event(struct ntb_dev *ntb, int vector)
> }
> EXPORT_SYMBOL(ntb_db_event);
>
> +void ntb_msg_event(struct ntb_dev *ntb)
> +{
> + unsigned long irqflags;
> +
> + spin_lock_irqsave(&ntb->ctx_lock, irqflags);
> + {
> + if (ntb->ctx_ops && ntb->ctx_ops->msg_event)
> + ntb->ctx_ops->msg_event(ntb->ctx);
> + }
> + spin_unlock_irqrestore(&ntb->ctx_lock, irqflags);
> +}
> +EXPORT_SYMBOL(ntb_msg_event);
> +
> static int ntb_probe(struct device *dev)
> {
> struct ntb_dev *ntb;
> diff --git a/include/linux/ntb.h b/include/linux/ntb.h
> index 4a150b5..59de1f6 100644
> --- a/include/linux/ntb.h
> +++ b/include/linux/ntb.h
> @@ -146,10 +146,12 @@ static inline int ntb_client_ops_is_valid(const struct
> ntb_client_ops *ops)
> * struct ntb_ctx_ops - ntb driver context operations
> * @link_event: See ntb_link_event().
> * @db_event: See ntb_db_event().
> + * @msg_event: See ntb_msg_event().
> */
> struct ntb_ctx_ops {
> void (*link_event)(void *ctx);
> void (*db_event)(void *ctx, int db_vector);
> + void (*msg_event)(void *ctx);
> };
>
> static inline int ntb_ctx_ops_is_valid(const struct ntb_ctx_ops *ops)
> @@ -158,6 +160,7 @@ static inline int ntb_ctx_ops_is_valid(const struct ntb_ctx_ops *ops)
> return
> /* ops->link_event && */
> /* ops->db_event && */
> + /* ops->msg_event && */
> 1;
> }
>
> @@ -202,6 +205,15 @@ static inline int ntb_ctx_ops_is_valid(const struct ntb_ctx_ops *ops)
> * @peer_spad_addr: See ntb_peer_spad_addr().
> * @peer_spad_read: See ntb_peer_spad_read().
> * @peer_spad_write: See ntb_peer_spad_write().
> + * @msg_count: See ntb_msg_count().
> + * @msg_inbits: See ntb_msg_inbits().
> + * @msg_outbits: See ntb_msg_outbits().
> + * @msg_read_sts: See ntb_msg_read_sts().
> + * @msg_clear_sts: See ntb_msg_clear_sts().
> + * @msg_set_mask: See ntb_msg_set_mask().
> + * @msg_clear_mask: See ntb_msg_clear_mask().
> + * @msg_read: See ntb_msg_read().
> + * @msg_write: See ntb_msg_write().
> */
> struct ntb_dev_ops {
> int (*port_number)(struct ntb_dev *ntb);
> @@ -263,6 +275,16 @@ struct ntb_dev_ops {
> phys_addr_t *spad_addr);
> u32 (*peer_spad_read)(struct ntb_dev *ntb, int idx);
> int (*peer_spad_write)(struct ntb_dev *ntb, int idx, u32 val);
> +
> + int (*msg_count)(struct ntb_dev *ntb);
> + u64 (*msg_inbits)(struct ntb_dev *ntb);
> + u64 (*msg_outbits)(struct ntb_dev *ntb);
> + u64 (*msg_read_sts)(struct ntb_dev *ntb);
> + int (*msg_clear_sts)(struct ntb_dev *ntb, u64 sts_bits);
> + int (*msg_set_mask)(struct ntb_dev *ntb, u64 mask_bits);
> + int (*msg_clear_mask)(struct ntb_dev *ntb, u64 mask_bits);
> + int (*msg_read)(struct ntb_dev *ntb, int midx, int *pidx, u32 *msg);
> + int (*msg_write)(struct ntb_dev *ntb, int midx, int pidx, u32 msg);
> };
>
> static inline int ntb_dev_ops_is_valid(const struct ntb_dev_ops *ops)
> @@ -304,13 +326,22 @@ static inline int ntb_dev_ops_is_valid(const struct ntb_dev_ops
> *ops)
> /* ops->peer_db_read_mask && */
> /* ops->peer_db_set_mask && */
> /* ops->peer_db_clear_mask && */
> - /* ops->spad_is_unsafe && */
> - ops->spad_count &&
> - ops->spad_read &&
> - ops->spad_write &&
> - /* ops->peer_spad_addr && */
> - /* ops->peer_spad_read && */
> - ops->peer_spad_write &&
> + ((/* ops->spad_is_unsafe && */
> + ops->spad_count &&
> + ops->spad_read &&
> + ops->spad_write &&
> + /* ops->peer_spad_addr && */
> + /* ops->peer_spad_read && */
> + ops->peer_spad_write) ||
> + (ops->msg_count &&
> + ops->msg_inbits &&
> + ops->msg_outbits &&
> + ops->msg_read_sts &&
> + ops->msg_clear_sts &&
> + /* ops->msg_set_mask && */
> + /* ops->msg_clear_mask && */
> + ops->msg_read &&
> + ops->msg_write)) &&

Don't enforce "must have spad or msg" here, leave it to application to check spad_count != 0 or msg_count != 0 else fail. If an ntb doesn't have either, it may be rather limited, but let's not prevent the driver to register that device.

As written above has a subtle bug. We should say, if spad is implemented at all, then the basic spad api is fully implemented; likewise if msg is implemented at all, then the basic msg api is fully implemented.

As written below, the required basic api of spad ops must have the same truth-value of spad_count (and likewise for msg_count).

/* !ops->spad_is_unsafe == !ops->spad_count && */
!ops->spad_read == !ops->spad_count &&
!ops->spad_write == !ops->spad_count &&
/* !ops->peer_spad_addr == !ops->spad_count && */
/* !ops->peer_spad_read == !ops->spad_count && */
!ops->peer_spad_write == !ops->spad_count &&

!ops->msg_inbits == !ops->msg_count &&
!ops->msg_outbits == !ops->msg_count &&
!ops->msg_read_sts == !ops->msg_count &&
!ops->msg_clear_sts == !ops->msg_count &&
/* !ops->msg_set_mask == !ops->msg_count && */
/* !ops->msg_clear_mask == !ops->msg_count && */
!ops->msg_read == !ops->msg_count &&
!ops->msg_write == !ops->msg_count &&

> 1;
> }
>
> @@ -456,6 +487,18 @@ void ntb_link_event(struct ntb_dev *ntb);
> void ntb_db_event(struct ntb_dev *ntb, int vector);
>
> /**
> + * ntb_msg_event() - notify driver context of a message event
> + * @ntb: NTB device context.
> + *
> + * Notify the driver context of a message event. If hardware supports
> + * message registers, this event indicates, that a new message arrived in
> + * some incoming message register or last sent message couldn't be delivered.
> + * The events can be masked/unmasked by the methods ntb_msg_set_mask() and
> + * ntb_msg_clear_mask().
> + */
> +void ntb_msg_event(struct ntb_dev *ntb);
> +
> +/**
> * ntb_port_number() - get the local port number
> * @ntb: NTB device context.
> *
> @@ -1154,7 +1197,7 @@ static inline int ntb_spad_is_unsafe(struct ntb_dev *ntb)
> }
>
> /**
> - * ntb_mw_count() - get the number of scratchpads
> + * ntb_spad_count() - get the number of scratchpads
> * @ntb: NTB device context.
> *
> * Hardware and topology may support a different number of scratchpads.
> @@ -1163,6 +1206,9 @@ static inline int ntb_spad_is_unsafe(struct ntb_dev *ntb)
> */
> static inline int ntb_spad_count(struct ntb_dev *ntb)
> {
> + if (!ntb->ops->spad_count)
> + return 0;
> +
> return ntb->ops->spad_count(ntb);
> }
>
> @@ -1177,6 +1223,9 @@ static inline int ntb_spad_count(struct ntb_dev *ntb)
> */
> static inline u32 ntb_spad_read(struct ntb_dev *ntb, int idx)
> {
> + if (!ntb->ops->spad_read)
> + return ~(u32)0;
> +
> return ntb->ops->spad_read(ntb, idx);
> }
>
> @@ -1192,6 +1241,9 @@ static inline u32 ntb_spad_read(struct ntb_dev *ntb, int idx)
> */
> static inline int ntb_spad_write(struct ntb_dev *ntb, int idx, u32 val)
> {
> + if (!ntb->ops->spad_write)
> + return -EINVAL;
> +
> return ntb->ops->spad_write(ntb, idx, val);
> }
>
> @@ -1226,6 +1278,9 @@ static inline int ntb_peer_spad_addr(struct ntb_dev *ntb, int idx,
> */
> static inline u32 ntb_peer_spad_read(struct ntb_dev *ntb, int idx)
> {
> + if (!ntb->ops->peer_spad_read)
> + return ~(u32)0;
> +
> return ntb->ops->peer_spad_read(ntb, idx);
> }
>
> @@ -1241,7 +1296,172 @@ static inline u32 ntb_peer_spad_read(struct ntb_dev *ntb, int idx)
> */
> static inline int ntb_peer_spad_write(struct ntb_dev *ntb, int idx, u32 val)
> {
> + if (!ntb->ops->peer_spad_write)
> + return -EINVAL;
> +
> return ntb->ops->peer_spad_write(ntb, idx, val);
> }
>
> +/**
> + * ntb_msg_count() - get the number of message registers
> + * @ntb: NTB device context.
> + *
> + * Hardware may support a different number of messge registers.
> + *
> + * Return: the number of message registers.
> + */
> +static inline int ntb_msg_count(struct ntb_dev *ntb)
> +{
> + if (!ntb->ops->msg_count)
> + return 0;
> +
> + return ntb->ops->msg_count(ntb);
> +}
> +
> +/**
> + * ntb_msg_inbits() - get a bitsfield of inbound message registers status
> + * @ntb: NTB device context.
> + *
> + * The method returns the bitsfield of status and mask registers, which related
> + * to inbound message registers.
> + *
> + * Return: bitsfield of inbound message registers.
> + */
> +static inline u64 ntb_msg_inbits(struct ntb_dev *ntb)
> +{
> + if (!ntb->ops->msg_inbits)
> + return 0;
> +
> + return ntb->ops->msg_inbits(ntb);
> +}
> +
> +/**
> + * ntb_msg_outbits() - get a bitsfield of outbound message registers status
> + * @ntb: NTB device context.
> + *
> + * The method returns the bitsfield of status and mask registers, which related
> + * to outbound message registers.
> + *
> + * Return: bitsfield of outbound message registers.
> + */
> +static inline u64 ntb_msg_outbits(struct ntb_dev *ntb)
> +{
> + if (!ntb->ops->msg_outbits)
> + return 0;
> +
> + return ntb->ops->msg_outbits(ntb);
> +}
> +
> +/**
> + * ntb_msg_read_sts() - read the message registers status
> + * @ntb: NTB device context.
> + *
> + * Read the status of message register. Inbound and outbound message registers
> + * related bits can be filetered by masks retrieved from ntb_msg_inbits() and
> + * ntb_msg_outbits().
> + *
> + * Return: status bits of message registers
> + */
> +static inline u64 ntb_msg_read_sts(struct ntb_dev *ntb)
> +{
> + if (!ntb->ops->msg_read_sts)
> + return 0;
> +
> + return ntb->ops->msg_read_sts(ntb);
> +}
> +
> +/**
> + * ntb_msg_clear_sts() - clear status bits of message registers
> + * @ntb: NTB device context.
> + * @sts_bits: Status bits to clear.
> + *
> + * Clear bits in the status register.
> + *
> + * Return: Zero on success, otherwise a negative error number.
> + */
> +static inline int ntb_msg_clear_sts(struct ntb_dev *ntb, u64 sts_bits)
> +{
> + if (!ntb->ops->msg_clear_sts)
> + return -EINVAL;
> +
> + return ntb->ops->msg_clear_sts(ntb, sts_bits);
> +}
> +
> +/**
> + * ntb_msg_set_mask() - set mask of message register status bits
> + * @ntb: NTB device context.
> + * @mask_bits: Mask bits.
> + *
> + * Mask the message registers status bits from raising the message event.
> + *
> + * Return: Zero on success, otherwise a negative error number.
> + */
> +static inline int ntb_msg_set_mask(struct ntb_dev *ntb, u64 mask_bits)
> +{
> + if (!ntb->ops->msg_set_mask)
> + return -EINVAL;
> +
> + return ntb->ops->msg_set_mask(ntb, mask_bits);
> +}
> +
> +/**
> + * ntb_msg_clear_mask() - clear message registers mask
> + * @ntb: NTB device context.
> + * @mask_bits: Mask bits to clear.
> + *
> + * Clear bits in the message events mask register.
> + *
> + * Return: Zero on success, otherwise a negative error number.
> + */
> +static inline int ntb_msg_clear_mask(struct ntb_dev *ntb, u64 mask_bits)
> +{
> + if (!ntb->ops->msg_clear_mask)
> + return -EINVAL;
> +
> + return ntb->ops->msg_clear_mask(ntb, mask_bits);
> +}
> +
> +/**
> + * ntb_msg_read() - read message register with specified index
> + * @ntb: NTB device context.
> + * @midx: Message register index
> + * @pidx: OUT - Port index of peer device a message retrieved from
> + * @msg: OUT - Data
> + *
> + * Read data from the specified message register. Source port index of a
> + * message is retrieved as well.
> + *
> + * Return: Zero on success, otherwise a negative error number.
> + */
> +static inline int ntb_msg_read(struct ntb_dev *ntb, int midx, int *pidx,
> + u32 *msg)
> +{
> + if (!ntb->ops->msg_read)
> + return -EINVAL;
> +
> + return ntb->ops->msg_read(ntb, midx, pidx, msg);
> +}
> +
> +/**
> + * ntb_msg_write() - write data to the specified message register
> + * @ntb: NTB device context.
> + * @midx: Message register index
> + * @pidx: Port index of peer device a message being sent to
> + * @msg: Data to send
> + *
> + * Send data to a specified peer device using the defined message register.
> + * Message event can be raised if the midx registers isn't empty while
> + * calling this method and the corresponding interrupt isn't masked.
> + *
> + * Return: Zero on success, otherwise a negative error number.
> + */
> +static inline int ntb_msg_write(struct ntb_dev *ntb, int midx, int pidx,
> + u32 msg)
> +{
> + if (!ntb->ops->msg_write)
> + return -EINVAL;
> +
> + return ntb->ops->msg_write(ntb, midx, pidx, msg);
> +}
> +
> #endif
> --
> 2.6.6

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