Re: [PATCH 3/3] mailbox: zynqmp: Enable Bufferless IPI usage on Versal-based SOC's

[Michal Simek <michal.simek@amd.com>]

On 12/14/23 22:13, Ben Levinsky wrote:
> On Xilinx-AMD Versal and Versal-NET, there exist both
> inter-processor-interrupts with corresponding message buffers and without
> such buffers.
> 
> Add a routine that, if the corresponding DT compatible
> string "xlnx,versal-ipi-mailbox" is used then a Versal-based SOC
> can use a mailbox Device Tree entry where both host and remote
> can use either of the buffered or bufferless interrupts.
> 
> Signed-off-by: Ben Levinsky <ben.levinsky@amd.com>
> ---
> Note that the linked patch provides corresponding bindings.
> Depends on: https://lore.kernel.org/all/20231214054224.957336-3-tanmay.shah@amd.com/T/
> ---
>   drivers/mailbox/zynqmp-ipi-mailbox.c | 146 +++++++++++++++++++++++++--
>   1 file changed, 139 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/mailbox/zynqmp-ipi-mailbox.c b/drivers/mailbox/zynqmp-ipi-mailbox.c
> index edefb80a6e47..316d9406064e 100644
> --- a/drivers/mailbox/zynqmp-ipi-mailbox.c
> +++ b/drivers/mailbox/zynqmp-ipi-mailbox.c
> @@ -52,6 +52,13 @@
>   #define IPI_MB_CHNL_TX	0 /* IPI mailbox TX channel */
>   #define IPI_MB_CHNL_RX	1 /* IPI mailbox RX channel */
>   
> +/* IPI Message Buffer Information */
> +#define RESP_OFFSET	0x20U
> +#define DEST_OFFSET	0x40U
> +#define IPI_BUF_SIZE	0x20U
> +#define DST_BIT_POS	9U
> +#define SRC_BITMASK	GENMASK(11, 8)
> +
>   /**
>    * struct zynqmp_ipi_mchan - Description of a Xilinx ZynqMP IPI mailbox channel
>    * @is_opened: indicate if the IPI channel is opened
> @@ -170,9 +177,11 @@ static irqreturn_t zynqmp_ipi_interrupt(int irq, void *data)
>   		if (ret > 0 && ret & IPI_MB_STATUS_RECV_PENDING) {
>   			if (mchan->is_opened) {
>   				msg = mchan->rx_buf;
> -				msg->len = mchan->req_buf_size;
> -				memcpy_fromio(msg->data, mchan->req_buf,
> -					      msg->len);
> +				if (msg) {
> +					msg->len = mchan->req_buf_size;
> +					memcpy_fromio(msg->data, mchan->req_buf,
> +						      msg->len);
> +				}
>   				mbox_chan_received_data(chan, (void *)msg);
>   				status = IRQ_HANDLED;
>   			}
> @@ -282,26 +291,26 @@ static int zynqmp_ipi_send_data(struct mbox_chan *chan, void *data)
>   
>   	if (mchan->chan_type == IPI_MB_CHNL_TX) {
>   		/* Send request message */
> -		if (msg && msg->len > mchan->req_buf_size) {
> +		if (msg && msg->len > mchan->req_buf_size && mchan->req_buf) {
>   			dev_err(dev, "channel %d message length %u > max %lu\n",
>   				mchan->chan_type, (unsigned int)msg->len,
>   				mchan->req_buf_size);
>   			return -EINVAL;
>   		}
> -		if (msg && msg->len)
> +		if (msg && msg->len && mchan->req_buf)
>   			memcpy_toio(mchan->req_buf, msg->data, msg->len);
>   		/* Kick IPI mailbox to send message */
>   		arg0 = SMC_IPI_MAILBOX_NOTIFY;
>   		zynqmp_ipi_fw_call(ipi_mbox, arg0, 0, &res);
>   	} else {
>   		/* Send response message */
> -		if (msg && msg->len > mchan->resp_buf_size) {
> +		if (msg && msg->len > mchan->resp_buf_size && mchan->resp_buf) {
>   			dev_err(dev, "channel %d message length %u > max %lu\n",
>   				mchan->chan_type, (unsigned int)msg->len,
>   				mchan->resp_buf_size);
>   			return -EINVAL;
>   		}
> -		if (msg && msg->len)
> +		if (msg && msg->len && mchan->resp_buf)
>   			memcpy_toio(mchan->resp_buf, msg->data, msg->len);
>   		arg0 = SMC_IPI_MAILBOX_ACK;
>   		zynqmp_ipi_fw_call(ipi_mbox, arg0, IPI_SMC_ACK_EIRQ_MASK,
> @@ -640,6 +649,126 @@ static int zynqmp_ipi_setup(struct zynqmp_ipi_mbox *ipi_mbox,
>   	return 0;
>   }
>   
> +/**
> + * versal_ipi_setup - Set up IPIs to support mixed usage of
> + *				 Buffered and Bufferless IPIs.
> + *
> + * @ipi_mbox: pointer to IPI mailbox private data structure
> + * @node: IPI mailbox device node
> + *
> + * Return: 0 for success, negative value for failure
> + */
> +static int versal_ipi_setup(struct zynqmp_ipi_mbox *ipi_mbox,
> +			    struct device_node *node)
> +{
> +	struct zynqmp_ipi_mchan *tx_mchan, *rx_mchan;
> +	struct resource host_res, remote_res;
> +	struct device_node *parent_node;
> +	int host_idx, remote_idx;
> +	struct device *mdev, *dev;
> +
> +	tx_mchan = &ipi_mbox->mchans[IPI_MB_CHNL_TX];
> +	rx_mchan = &ipi_mbox->mchans[IPI_MB_CHNL_RX];
> +	parent_node = of_get_parent(node);
> +	dev = ipi_mbox->pdata->dev;
> +	mdev = &ipi_mbox->dev;
> +
> +	host_idx = zynqmp_ipi_mbox_get_buf_res(parent_node, "msg", &host_res);
> +	remote_idx = zynqmp_ipi_mbox_get_buf_res(node, "msg", &remote_res);
> +
> +	/*
> +	 * Only set up buffers if both sides claim to have msg buffers.
> +	 * This is because each buffered IPI's corresponding msg buffers
> +	 * are reserved for use by other buffered IPI's.
> +	 */
> +	if (!host_idx && !remote_idx) {
> +		u32 host_src, host_dst, remote_src, remote_dst;
> +		u32 buff_sz;
> +
> +		buff_sz = resource_size(&host_res);
> +
> +		host_src = host_res.start & SRC_BITMASK;
> +		remote_src = remote_res.start & SRC_BITMASK;
> +
> +		host_dst = (host_src >> DST_BIT_POS) * DEST_OFFSET;
> +		remote_dst = (remote_src >> DST_BIT_POS) * DEST_OFFSET;
> +
> +		/* Validate that IPI IDs is within IPI Message buffer space. */
> +		if (host_dst >= buff_sz || remote_dst >= buff_sz) {
> +			dev_err(mdev,
> +				"Invalid IPI Message buffer values: %x %x\n",
> +				host_dst, remote_dst);
> +			return -EINVAL;
> +		}
> +
> +		tx_mchan->req_buf = devm_ioremap(mdev,
> +						 host_res.start | remote_dst,
> +						 IPI_BUF_SIZE);
> +		if (!tx_mchan->req_buf) {
> +			dev_err(mdev, "Unable to map IPI buffer I/O memory\n");
> +			return -ENOMEM;
> +		}
> +
> +		tx_mchan->resp_buf = devm_ioremap(mdev,
> +						  (remote_res.start | host_dst) +
> +						  RESP_OFFSET, IPI_BUF_SIZE);
> +		if (!tx_mchan->resp_buf) {
> +			dev_err(mdev, "Unable to map IPI buffer I/O memory\n");
> +			return -ENOMEM;
> +		}
> +
> +		rx_mchan->req_buf = devm_ioremap(mdev,
> +						 remote_res.start | host_dst,
> +						 IPI_BUF_SIZE);
> +		if (!rx_mchan->req_buf) {
> +			dev_err(mdev, "Unable to map IPI buffer I/O memory\n");
> +			return -ENOMEM;
> +		}
> +
> +		rx_mchan->resp_buf = devm_ioremap(mdev,
> +						  (host_res.start | remote_dst) +
> +						  RESP_OFFSET, IPI_BUF_SIZE);
> +		if (!rx_mchan->resp_buf) {
> +			dev_err(mdev, "Unable to map IPI buffer I/O memory\n");
> +			return -ENOMEM;
> +		}
> +
> +		tx_mchan->resp_buf_size = IPI_BUF_SIZE;
> +		tx_mchan->req_buf_size = IPI_BUF_SIZE;
> +		tx_mchan->rx_buf = devm_kzalloc(mdev, IPI_BUF_SIZE +
> +						sizeof(struct zynqmp_ipi_message),
> +						GFP_KERNEL);
> +		if (!tx_mchan->rx_buf)
> +			return -ENOMEM;
> +
> +		rx_mchan->resp_buf_size = IPI_BUF_SIZE;
> +		rx_mchan->req_buf_size = IPI_BUF_SIZE;
> +		rx_mchan->rx_buf = devm_kzalloc(mdev, IPI_BUF_SIZE +
> +						sizeof(struct zynqmp_ipi_message),
> +						GFP_KERNEL);
> +		if (!rx_mchan->rx_buf)
> +			return -ENOMEM;
> +	} else {
> +		/*
> +		 * If here, then set up Bufferless IPI Channel because
> +		 * one or both of the IPI's is bufferless.
> +		 */
> +		tx_mchan->req_buf = NULL;
> +		tx_mchan->resp_buf = NULL;
> +		tx_mchan->rx_buf = NULL;
> +		tx_mchan->resp_buf_size = 0;
> +		tx_mchan->req_buf_size = 0;
> +
> +		rx_mchan->req_buf = NULL;
> +		rx_mchan->resp_buf = NULL;
> +		rx_mchan->rx_buf = NULL;
> +		rx_mchan->resp_buf_size = 0;
> +		rx_mchan->req_buf_size = 0;

Just curious if this is really needed. If none fills that values aren't they 
actually already 0/NULL because that location is cleared by kzalloc.

Thanks,
Michal


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