> Subject: [PATCH v3 2/2] firmware: arm_scmi: Support 'reg-io-width'
> property for shared memory
>
> Some shared memory areas might only support a certain access width,
> such as 32-bit, which memcpy_{from,to}_io() does not adhere to at
> least on ARM64 by making both 8-bit and 64-bit accesses to such
> memory.
>
> Update the shmem layer to support reading from and writing to such
> shared memory area using the specified I/O width in the Device Tree.
> The various transport layers making use of the shmem.c code are
> updated accordingly to pass the I/O accessors that they store.
>
> Signed-off-by: Florian Fainelli <florian.fainelli@xxxxxxxxxxxx>
> ---
> drivers/firmware/arm_scmi/common.h | 32 ++++++-
> .../arm_scmi/scmi_transport_mailbox.c | 13 ++-
> .../firmware/arm_scmi/scmi_transport_optee.c | 11 ++-
> .../firmware/arm_scmi/scmi_transport_smc.c | 11 ++-
> drivers/firmware/arm_scmi/shmem.c | 86 +++++++++++++++++-
> -
> 5 files changed, 132 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/firmware/arm_scmi/common.h
> b/drivers/firmware/arm_scmi/common.h
> index 69928bbd01c2..73bb496fac01 100644
> --- a/drivers/firmware/arm_scmi/common.h
> +++ b/drivers/firmware/arm_scmi/common.h
> @@ -316,6 +316,26 @@ enum scmi_bad_msg {
> MSG_MBOX_SPURIOUS = -5,
> };
>
> +/* Used for compactness and signature validation of the function
> +pointers being
> + * passed.
> + */
> +typedef void (*shmem_copy_toio_t)(volatile void __iomem *to, const
> void *from,
> + size_t count);
> +typedef void (*shmem_copy_fromio_t)(void *to, const volatile void
> __iomem *from,
> + size_t count);
> +
> +/**
> + * struct scmi_shmem_io_ops - I/O operations to read from/write to
> + * Shared Memory
> + *
> + * @toio: Copy data to the shared memory area
> + * @fromio: Copy data from the shared memory area */ struct
> +scmi_shmem_io_ops {
> + shmem_copy_fromio_t fromio;
> + shmem_copy_toio_t toio;
> +};
> +
> /* shmem related declarations */
> struct scmi_shared_mem;
>
> @@ -336,13 +356,16 @@ struct scmi_shared_mem; struct
> scmi_shared_mem_operations {
> void (*tx_prepare)(struct scmi_shared_mem __iomem
> *shmem,
> struct scmi_xfer *xfer,
> - struct scmi_chan_info *cinfo);
> + struct scmi_chan_info *cinfo,
> + shmem_copy_toio_t toio);
> u32 (*read_header)(struct scmi_shared_mem __iomem
> *shmem);
>
> void (*fetch_response)(struct scmi_shared_mem __iomem
> *shmem,
> - struct scmi_xfer *xfer);
> + struct scmi_xfer *xfer,
> + shmem_copy_fromio_t fromio);
> void (*fetch_notification)(struct scmi_shared_mem __iomem
> *shmem,
> - size_t max_len, struct scmi_xfer
> *xfer);
> + size_t max_len, struct scmi_xfer
> *xfer,
> + shmem_copy_fromio_t fromio);
> void (*clear_channel)(struct scmi_shared_mem __iomem
> *shmem);
> bool (*poll_done)(struct scmi_shared_mem __iomem *shmem,
> struct scmi_xfer *xfer);
> @@ -350,7 +373,8 @@ struct scmi_shared_mem_operations {
> bool (*channel_intr_enabled)(struct scmi_shared_mem
> __iomem *shmem);
> void __iomem *(*setup_iomap)(struct scmi_chan_info *cinfo,
> struct device *dev,
> - bool tx, struct resource *res);
> + bool tx, struct resource *res,
> + struct scmi_shmem_io_ops **ops);
> };
>
> const struct scmi_shared_mem_operations
> *scmi_shared_mem_operations_get(void);
> diff --git a/drivers/firmware/arm_scmi/scmi_transport_mailbox.c
> b/drivers/firmware/arm_scmi/scmi_transport_mailbox.c
> index dc5ca894d5eb..1a2e90e5c765 100644
> --- a/drivers/firmware/arm_scmi/scmi_transport_mailbox.c
> +++ b/drivers/firmware/arm_scmi/scmi_transport_mailbox.c
> @@ -25,6 +25,7 @@
> * @chan_platform_receiver: Optional Platform Receiver mailbox
> unidirectional channel
> * @cinfo: SCMI channel info
> * @shmem: Transmit/Receive shared memory area
> + * @io_ops: Transport specific I/O operations
> */
> struct scmi_mailbox {
> struct mbox_client cl;
> @@ -33,6 +34,7 @@ struct scmi_mailbox {
> struct mbox_chan *chan_platform_receiver;
> struct scmi_chan_info *cinfo;
> struct scmi_shared_mem __iomem *shmem;
> + struct scmi_shmem_io_ops *io_ops;
> };
>
> #define client_to_scmi_mailbox(c) container_of(c, struct scmi_mailbox,
> cl) @@ -43,7 +45,8 @@ static void tx_prepare(struct mbox_client *cl,
> void *m) {
> struct scmi_mailbox *smbox = client_to_scmi_mailbox(cl);
>
> - core->shmem->tx_prepare(smbox->shmem, m, smbox->cinfo);
> + core->shmem->tx_prepare(smbox->shmem, m, smbox->cinfo,
> + smbox->io_ops->toio);
> }
>
> static void rx_callback(struct mbox_client *cl, void *m) @@ -197,7
> +200,8 @@ static int mailbox_chan_setup(struct scmi_chan_info
> *cinfo, struct device *dev,
> if (!smbox)
> return -ENOMEM;
>
> - smbox->shmem = core->shmem->setup_iomap(cinfo, dev, tx,
> NULL);
> + smbox->shmem = core->shmem->setup_iomap(cinfo, dev, tx,
> NULL,
> + &smbox->io_ops);
> if (IS_ERR(smbox->shmem))
> return PTR_ERR(smbox->shmem);
>
> @@ -298,7 +302,7 @@ static void mailbox_fetch_response(struct
> scmi_chan_info *cinfo, {
> struct scmi_mailbox *smbox = cinfo->transport_info;
>
> - core->shmem->fetch_response(smbox->shmem, xfer);
> + core->shmem->fetch_response(smbox->shmem, xfer,
> +smbox->io_ops->fromio);
> }
>
> static void mailbox_fetch_notification(struct scmi_chan_info *cinfo,
> @@ -306,7 +310,8 @@ static void mailbox_fetch_notification(struct
> scmi_chan_info *cinfo, {
> struct scmi_mailbox *smbox = cinfo->transport_info;
>
> - core->shmem->fetch_notification(smbox->shmem, max_len,
> xfer);
> + core->shmem->fetch_notification(smbox->shmem, max_len,
> xfer,
> + smbox->io_ops->fromio);
> }
>
> static void mailbox_clear_channel(struct scmi_chan_info *cinfo) diff --
> git a/drivers/firmware/arm_scmi/scmi_transport_optee.c
> b/drivers/firmware/arm_scmi/scmi_transport_optee.c
> index 08911f40d1ff..2be4124c6826 100644
> --- a/drivers/firmware/arm_scmi/scmi_transport_optee.c
> +++ b/drivers/firmware/arm_scmi/scmi_transport_optee.c
> @@ -114,6 +114,7 @@ enum scmi_optee_pta_cmd {
> * @req.shmem: Virtual base address of the shared memory
> * @req.msg: Shared memory protocol handle for SCMI request and
> * synchronous response
> + * @io_ops: Transport specific I/O operations
> * @tee_shm: TEE shared memory handle @req or NULL if using
> IOMEM shmem
> * @link: Reference in agent's channel list
> */
> @@ -128,6 +129,7 @@ struct scmi_optee_channel {
> struct scmi_shared_mem __iomem *shmem;
> struct scmi_msg_payld *msg;
> } req;
> + struct scmi_shmem_io_ops *io_ops;
> struct tee_shm *tee_shm;
> struct list_head link;
> };
> @@ -350,7 +352,8 @@ static int setup_dynamic_shmem(struct device
> *dev, struct scmi_optee_channel *ch static int
> setup_static_shmem(struct device *dev, struct scmi_chan_info *cinfo,
> struct scmi_optee_channel *channel) {
> - channel->req.shmem = core->shmem->setup_iomap(cinfo, dev,
> true, NULL);
> + channel->req.shmem = core->shmem->setup_iomap(cinfo, dev,
> true, NULL,
> + &channel-
> >io_ops);
> if (IS_ERR(channel->req.shmem))
> return PTR_ERR(channel->req.shmem);
>
> @@ -465,7 +468,8 @@ static int scmi_optee_send_message(struct
> scmi_chan_info *cinfo,
> ret = invoke_process_msg_channel(channel,
> core->msg-
> >command_size(xfer));
> } else {
> - core->shmem->tx_prepare(channel->req.shmem, xfer,
> cinfo);
> + core->shmem->tx_prepare(channel->req.shmem, xfer,
> cinfo,
> + channel->io_ops->toio);
> ret = invoke_process_smt_channel(channel);
> }
>
> @@ -484,7 +488,8 @@ static void scmi_optee_fetch_response(struct
> scmi_chan_info *cinfo,
> core->msg->fetch_response(channel->req.msg,
> channel->rx_len, xfer);
> else
> - core->shmem->fetch_response(channel->req.shmem,
> xfer);
> + core->shmem->fetch_response(channel->req.shmem,
> xfer,
> + channel->io_ops->fromio);
> }
>
> static void scmi_optee_mark_txdone(struct scmi_chan_info *cinfo, int
> ret, diff --git a/drivers/firmware/arm_scmi/scmi_transport_smc.c
> b/drivers/firmware/arm_scmi/scmi_transport_smc.c
> index c6c69a17a9cc..04e715ec1570 100644
> --- a/drivers/firmware/arm_scmi/scmi_transport_smc.c
> +++ b/drivers/firmware/arm_scmi/scmi_transport_smc.c
> @@ -45,6 +45,7 @@
> * @irq: An optional IRQ for completion
> * @cinfo: SCMI channel info
> * @shmem: Transmit/Receive shared memory area
> + * @io_ops: Transport specific I/O operations
> * @shmem_lock: Lock to protect access to Tx/Rx shared memory area.
> * Used when NOT operating in atomic mode.
> * @inflight: Atomic flag to protect access to Tx/Rx shared memory
> area.
> @@ -60,6 +61,7 @@ struct scmi_smc {
> int irq;
> struct scmi_chan_info *cinfo;
> struct scmi_shared_mem __iomem *shmem;
> + struct scmi_shmem_io_ops *io_ops;
> /* Protect access to shmem area */
> struct mutex shmem_lock;
> #define INFLIGHT_NONE MSG_TOKEN_MAX
> @@ -144,7 +146,8 @@ static int smc_chan_setup(struct
> scmi_chan_info *cinfo, struct device *dev,
> if (!scmi_info)
> return -ENOMEM;
>
> - scmi_info->shmem = core->shmem->setup_iomap(cinfo, dev,
> tx, &res);
> + scmi_info->shmem = core->shmem->setup_iomap(cinfo, dev,
> tx, &res,
> + &scmi_info-
> >io_ops);
> if (IS_ERR(scmi_info->shmem))
> return PTR_ERR(scmi_info->shmem);
>
> @@ -229,7 +232,8 @@ static int smc_send_message(struct
> scmi_chan_info *cinfo,
> */
> smc_channel_lock_acquire(scmi_info, xfer);
>
> - core->shmem->tx_prepare(scmi_info->shmem, xfer, cinfo);
> + core->shmem->tx_prepare(scmi_info->shmem, xfer, cinfo,
> + scmi_info->io_ops->toio);
>
> if (scmi_info->cap_id != ULONG_MAX)
> arm_smccc_1_1_invoke(scmi_info->func_id,
> scmi_info->cap_id, 0, @@ -253,7 +257,8 @@ static void
> smc_fetch_response(struct scmi_chan_info *cinfo, {
> struct scmi_smc *scmi_info = cinfo->transport_info;
>
> - core->shmem->fetch_response(scmi_info->shmem, xfer);
> + core->shmem->fetch_response(scmi_info->shmem, xfer,
> + scmi_info->io_ops->fromio);
> }
>
> static void smc_mark_txdone(struct scmi_chan_info *cinfo, int ret, diff
> --git a/drivers/firmware/arm_scmi/shmem.c
> b/drivers/firmware/arm_scmi/shmem.c
> index 01d8a9398fe8..aded5f1cd49f 100644
> --- a/drivers/firmware/arm_scmi/shmem.c
> +++ b/drivers/firmware/arm_scmi/shmem.c
> @@ -34,9 +34,67 @@ struct scmi_shared_mem {
> u8 msg_payload[];
> };
>
> +static inline void shmem_memcpy_fromio32(void *to,
> + const volatile void __iomem
> *from,
> + size_t count)
> +{
> + while (count) {
> + *(u32 *)to = __raw_readl(from);
> + from += 4;
> + to += 4;
> + count -= 4;
This may not have issue, considering the 'count % 4' will be 0
and 'from' is 4 bytes aligned.
But I think it maybe better to add check if 'count' and 'from'
are not 4 bytes aligned.
> + }
> +
> + /* Ensure all reads from I/O have completed */
> + rmb();
Is there a need to use rmb here? I am not sure, just wonder.
> +}
> +
> +static inline void shmem_memcpy_toio32(volatile void __iomem *to,
> + const void *from,
> + size_t count)
> +{
> + while (count) {
> + __raw_writel(*(u32 *)from, to);
> + from += 4;
> + to += 4;
> + count -= 4;
> + }
Ditto.
> +
> + /* Ensure all writes to I/O have completed */
> + wmb();
This maybe not needed.
The mailbox will use "writel", the SMC will use "smc",
the virtio will have "hvc", both will have barrier I think.
Regards,
Peng.
> +}
> +
> +static struct scmi_shmem_io_ops shmem_io_ops32 = {
> + .fromio = shmem_memcpy_fromio32,
> + .toio = shmem_memcpy_toio32,
> +};
> +
> +/* Wrappers are needed for proper memcpy_{from,to}_io expansion
> by the
> + * pre-processor.
> + */
> +static inline void shmem_memcpy_fromio(void *to,
> + const volatile void __iomem
> *from,
> + size_t count)
> +{
> + memcpy_fromio(to, from, count);
> +}
> +
> +static inline void shmem_memcpy_toio(volatile void __iomem *to,
> + const void *from,
> + size_t count)
> +{
> + memcpy_toio(to, from, count);
> +}
> +
> +static struct scmi_shmem_io_ops shmem_io_ops_default = {
> + .fromio = shmem_memcpy_fromio,
> + .toio = shmem_memcpy_toio,
> +};
> +
> static void shmem_tx_prepare(struct scmi_shared_mem __iomem
> *shmem,
> struct scmi_xfer *xfer,
> - struct scmi_chan_info *cinfo)
> + struct scmi_chan_info *cinfo,
> + shmem_copy_toio_t copy_toio)
> {
> ktime_t stop;
>
> @@ -73,7 +131,7 @@ static void shmem_tx_prepare(struct
> scmi_shared_mem __iomem *shmem,
> iowrite32(sizeof(shmem->msg_header) + xfer->tx.len,
> &shmem->length);
> iowrite32(pack_scmi_header(&xfer->hdr), &shmem-
> >msg_header);
> if (xfer->tx.buf)
> - memcpy_toio(shmem->msg_payload, xfer->tx.buf,
> xfer->tx.len);
> + copy_toio(shmem->msg_payload, xfer->tx.buf, xfer-
> >tx.len);
> }
>
> static u32 shmem_read_header(struct scmi_shared_mem __iomem
> *shmem) @@ -82,7 +140,8 @@ static u32 shmem_read_header(struct
> scmi_shared_mem __iomem *shmem) }
>
> static void shmem_fetch_response(struct scmi_shared_mem __iomem
> *shmem,
> - struct scmi_xfer *xfer)
> + struct scmi_xfer *xfer,
> + shmem_copy_fromio_t copy_fromio)
> {
> size_t len = ioread32(&shmem->length);
>
> @@ -91,11 +150,12 @@ static void shmem_fetch_response(struct
> scmi_shared_mem __iomem *shmem,
> xfer->rx.len = min_t(size_t, xfer->rx.len, len > 8 ? len - 8 : 0);
>
> /* Take a copy to the rx buffer.. */
> - memcpy_fromio(xfer->rx.buf, shmem->msg_payload + 4, xfer-
> >rx.len);
> + copy_fromio(xfer->rx.buf, shmem->msg_payload + 4, xfer-
> >rx.len);
> }
>
> static void shmem_fetch_notification(struct scmi_shared_mem
> __iomem *shmem,
> - size_t max_len, struct scmi_xfer
> *xfer)
> + size_t max_len, struct scmi_xfer
> *xfer,
> + shmem_copy_fromio_t
> copy_fromio)
> {
> size_t len = ioread32(&shmem->length);
>
> @@ -103,7 +163,7 @@ static void shmem_fetch_notification(struct
> scmi_shared_mem __iomem *shmem,
> xfer->rx.len = min_t(size_t, max_len, len > 4 ? len - 4 : 0);
>
> /* Take a copy to the rx buffer.. */
> - memcpy_fromio(xfer->rx.buf, shmem->msg_payload, xfer-
> >rx.len);
> + copy_fromio(xfer->rx.buf, shmem->msg_payload, xfer->rx.len);
> }
>
> static void shmem_clear_channel(struct scmi_shared_mem __iomem
> *shmem) @@ -139,7 +199,8 @@ static bool
> shmem_channel_intr_enabled(struct scmi_shared_mem __iomem
> *shmem)
>
> static void __iomem *shmem_setup_iomap(struct scmi_chan_info
> *cinfo,
> struct device *dev, bool tx,
> - struct resource *res)
> + struct resource *res,
> + struct scmi_shmem_io_ops
> **ops)
> {
> struct device_node *shmem __free(device_node);
> const char *desc = tx ? "Tx" : "Rx";
> @@ -148,6 +209,7 @@ static void __iomem
> *shmem_setup_iomap(struct scmi_chan_info *cinfo,
> struct resource lres = {};
> resource_size_t size;
> void __iomem *addr;
> + u32 reg_io_width;
>
> shmem = of_parse_phandle(cdev->of_node, "shmem", idx);
> if (!shmem)
> @@ -173,6 +235,16 @@ static void __iomem
> *shmem_setup_iomap(struct scmi_chan_info *cinfo,
> return IOMEM_ERR_PTR(-EADDRNOTAVAIL);
> }
>
> + of_property_read_u32(shmem, "reg-io-width", ®_io_width);
> + switch (reg_io_width) {
> + case 4:
> + *ops = &shmem_io_ops32;
> + break;
> + default:
> + *ops = &shmem_io_ops_default;
> + break;
> + }
> +
> return addr;
> }
>
> --
> 2.34.1
>
