[PATCH v4 3/3] mctp pcc: Implement MCTP over PCC Transport

admiyo
2024-07-02T22:59:05Z

From: Adam Young <admiyo@os.amperecomputing.com>

Implementation of network driver for
Management Control Transport Protocol(MCTP) over
Platform Communication Channel(PCC)

DMTF DSP:0292

MCTP devices are specified by entries in DSDT/SDST and
reference channels specified in the PCCT.

Communication with other devices use the PCC based
doorbell mechanism.

Signed-off-by: Adam Young <admiyo@os.amperecomputing.com>
---
drivers/net/mctp/Kconfig | 13 ++
drivers/net/mctp/Makefile | 1 +
drivers/net/mctp/mctp-pcc.c | 322 ++++++++++++++++++++++++++++++++++++
3 files changed, 336 insertions(+)
create mode 100644 drivers/net/mctp/mctp-pcc.c

diff --git a/drivers/net/mctp/Kconfig b/drivers/net/mctp/Kconfig
index ce9d2d2ccf3b..ff4effd8e99c 100644
--- a/drivers/net/mctp/Kconfig
+++ b/drivers/net/mctp/Kconfig
@@ -42,6 +42,19 @@ config MCTP_TRANSPORT_I3C
A MCTP protocol network device is created for each I3C bus
having a "mctp-controller" devicetree property.

+config MCTP_TRANSPORT_PCC
+ tristate "MCTP PCC transport"
+ select ACPI
+ help
+ Provides a driver to access MCTP devices over PCC transport,
+ A MCTP protocol network device is created via ACPI for each
+ entry in the DST/SDST that matches the identifier. The Platform
+ commuinucation channels are selected from the corresponding
+ entries in the PCCT.
+
+ Say y here if you need to connect to MCTP endpoints over PCC. To
+ compile as a module, use m; the module will be called mctp-pcc.
+
endmenu

endif
diff --git a/drivers/net/mctp/Makefile b/drivers/net/mctp/Makefile
index e1cb99ced54a..492a9e47638f 100644
--- a/drivers/net/mctp/Makefile
+++ b/drivers/net/mctp/Makefile
@@ -1,3 +1,4 @@
+obj-$(CONFIG_MCTP_TRANSPORT_PCC) += mctp-pcc.o
obj-$(CONFIG_MCTP_SERIAL) += mctp-serial.o
obj-$(CONFIG_MCTP_TRANSPORT_I2C) += mctp-i2c.o
obj-$(CONFIG_MCTP_TRANSPORT_I3C) += mctp-i3c.o
diff --git a/drivers/net/mctp/mctp-pcc.c b/drivers/net/mctp/mctp-pcc.c
new file mode 100644
index 000000000000..50ebad0e0cbe
--- /dev/null
+++ b/drivers/net/mctp/mctp-pcc.c
@@ -0,0 +1,322 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * mctp-pcc.c - Driver for MCTP over PCC.
+ * Copyright (c) 2024, Ampere Computing LLC
+ */
+
+#include <linux/acpi.h>
+#include <linux/if_arp.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/platform_device.h>
+#include <linux/string.h>
+
+#include <acpi/acpi_bus.h>
+#include <acpi/acpi_drivers.h>
+#include <acpi/acrestyp.h>
+#include <acpi/actbl.h>
+#include <net/mctp.h>
+#include <net/mctpdevice.h>
+#include <acpi/pcc.h>
+
+#define MCTP_PAYLOAD_LENGTH 256
+#define MCTP_CMD_LENGTH 4
+#define MCTP_PCC_VERSION 0x1 /* DSP0253 defines a single version: 1 */
+#define MCTP_SIGNATURE "MCTP"
+#define SIGNATURE_LENGTH 4
+#define MCTP_HEADER_LENGTH 12
+#define MCTP_MIN_MTU 68
+#define PCC_MAGIC 0x50434300
+#define PCC_HEADER_FLAG_REQ_INT 0x1
+#define PCC_HEADER_FLAGS PCC_HEADER_FLAG_REQ_INT
+#define PCC_DWORD_TYPE 0x0c
+#define PCC_ACK_FLAG_MASK 0x1
+
+struct mctp_pcc_hdr {
+ u32 signature;
+ u32 flags;
+ u32 length;
+ char mctp_signature[4];
+};
+
+struct mctp_pcc_hw_addr {
+ u32 inbox_index;
+ u32 outbox_index;
+};
+
+/* The netdev structure. One of these per PCC adapter. */
+struct mctp_pcc_ndev {
+ struct list_head next;
+ /* spinlock to serialize access to pcc buffer and registers*/
+ spinlock_t lock;
+ struct mctp_dev mdev;
+ struct acpi_device *acpi_device;
+ struct pcc_mbox_chan *in_chan;
+ struct pcc_mbox_chan *out_chan;
+ struct mbox_client outbox_client;
+ struct mbox_client inbox_client;
+ void __iomem *pcc_comm_inbox_addr;
+ void __iomem *pcc_comm_outbox_addr;
+ struct mctp_pcc_hw_addr hw_addr;
+};
+
+static void mctp_pcc_client_rx_callback(struct mbox_client *c, void *buffer)
+{
+ struct mctp_pcc_ndev *mctp_pcc_dev;
+ struct mctp_pcc_hdr mctp_pcc_hdr;
+ struct mctp_skb_cb *cb;
+ struct sk_buff *skb;
+ void *skb_buf;
+ u32 data_len;
+
+ mctp_pcc_dev = container_of(c, struct mctp_pcc_ndev, inbox_client);
+ memcpy_fromio(&mctp_pcc_hdr, mctp_pcc_dev->pcc_comm_inbox_addr,
+ sizeof(struct mctp_pcc_hdr));
+ data_len = mctp_pcc_hdr.length + MCTP_HEADER_LENGTH;
+
+ if (data_len > mctp_pcc_dev->mdev.dev->max_mtu) {
+ mctp_pcc_dev->mdev.dev->stats.rx_dropped++;
+ return;
+ }
+
+ skb = netdev_alloc_skb(mctp_pcc_dev->mdev.dev, data_len);
+ if (!skb) {
+ mctp_pcc_dev->mdev.dev->stats.rx_dropped++;
+ return;
+ }
+ mctp_pcc_dev->mdev.dev->stats.rx_packets++;
+ mctp_pcc_dev->mdev.dev->stats.rx_bytes += data_len;
+ skb->protocol = htons(ETH_P_MCTP);
+ skb_buf = skb_put(skb, data_len);
+ memcpy_fromio(skb_buf, mctp_pcc_dev->pcc_comm_inbox_addr, data_len);
+
+ skb_reset_mac_header(skb);
+ skb_pull(skb, sizeof(struct mctp_pcc_hdr));
+ skb_reset_network_header(skb);
+ cb = __mctp_cb(skb);
+ cb->halen = 0;
+ netif_rx(skb);
+}
+
+static netdev_tx_t mctp_pcc_tx(struct sk_buff *skb, struct net_device *ndev)
+{
+ struct mctp_pcc_hdr pcc_header;
+ struct mctp_pcc_ndev *mpnd;
+ void __iomem *buffer;
+ unsigned long flags;
+
+ ndev->stats.tx_bytes += skb->len;
+ ndev->stats.tx_packets++;
+ mpnd = netdev_priv(ndev);
+
+ spin_lock_irqsave(&mpnd->lock, flags);
+ buffer = mpnd->pcc_comm_outbox_addr;
+ pcc_header.signature = PCC_MAGIC | mpnd->hw_addr.outbox_index;
+ pcc_header.flags = PCC_HEADER_FLAGS;
+ memcpy(pcc_header.mctp_signature, MCTP_SIGNATURE, SIGNATURE_LENGTH);
+ pcc_header.length = skb->len + SIGNATURE_LENGTH;
+ memcpy_toio(buffer, &pcc_header, sizeof(struct mctp_pcc_hdr));
+ memcpy_toio(buffer + sizeof(struct mctp_pcc_hdr), skb->data, skb->len);
+ mpnd->out_chan->mchan->mbox->ops->send_data(mpnd->out_chan->mchan,
+ NULL);
+ spin_unlock_irqrestore(&mpnd->lock, flags);
+
+ dev_consume_skb_any(skb);
+ return NETDEV_TX_OK;
+}
+
+static void
+mctp_pcc_net_stats(struct net_device *net_dev,
+ struct rtnl_link_stats64 *stats)
+{
+ struct mctp_pcc_ndev *mpnd;
+
+ mpnd = netdev_priv(net_dev);
+ stats->rx_errors = 0;
+ stats->rx_packets = mpnd->mdev.dev->stats.rx_packets;
+ stats->tx_packets = mpnd->mdev.dev->stats.tx_packets;
+ stats->rx_dropped = 0;
+ stats->tx_bytes = mpnd->mdev.dev->stats.tx_bytes;
+ stats->rx_bytes = mpnd->mdev.dev->stats.rx_bytes;
+}
+
+static const struct net_device_ops mctp_pcc_netdev_ops = {
+ .ndo_start_xmit = mctp_pcc_tx,
+ .ndo_get_stats64 = mctp_pcc_net_stats,
+};
+
+static void mctp_pcc_setup(struct net_device *ndev)
+{
+ ndev->type = ARPHRD_MCTP;
+ ndev->hard_header_len = 0;
+ ndev->addr_len = 0;
+ ndev->tx_queue_len = 0;
+ ndev->flags = IFF_NOARP;
+ ndev->netdev_ops = &mctp_pcc_netdev_ops;
+ ndev->needs_free_netdev = true;
+}
+
+struct lookup_context {
+ int index;
+ u32 inbox_index;
+ u32 outbox_index;
+};
+
+static acpi_status lookup_pcct_indices(struct acpi_resource *ares,
+ void *context)
+{
+ struct acpi_resource_address32 *addr;
+ struct lookup_context *luc = context;
+
+ switch (ares->type) {
+ case PCC_DWORD_TYPE:
+ break;
+ default:
+ return AE_OK;
+ }
+
+ addr = ACPI_CAST_PTR(struct acpi_resource_address32, &ares->data);
+ switch (luc->index) {
+ case 0:
+ luc->outbox_index = addr[0].address.minimum;
+ break;
+ case 1:
+ luc->inbox_index = addr[0].address.minimum;
+ break;
+ }
+ luc->index++;
+ return AE_OK;
+}
+
+static int mctp_pcc_driver_add(struct acpi_device *acpi_dev)
+{
+ struct lookup_context context = {0, 0, 0};
+ struct mctp_pcc_ndev *mctp_pcc_dev;
+ struct net_device *ndev;
+ acpi_handle dev_handle;
+ acpi_status status;
+ struct device *dev;
+ int mctp_pcc_mtu;
+ int outbox_index;
+ int inbox_index;
+ char name[32];
+ int rc;
+
+ dev_dbg(&acpi_dev->dev, "Adding mctp_pcc device for HID %s\n",
+ acpi_device_hid(acpi_dev));
+ dev_handle = acpi_device_handle(acpi_dev);
+ status = acpi_walk_resources(dev_handle, "_CRS", lookup_pcct_indices,
+ &context);
+ if (!ACPI_SUCCESS(status)) {
+ dev_err(&acpi_dev->dev, "FAILURE to lookup PCC indexes from CRS");
+ return -EINVAL;
+ }
+ inbox_index = context.inbox_index;
+ outbox_index = context.outbox_index;
+ dev = &acpi_dev->dev;
+
+ snprintf(name, sizeof(name), "mctpipcc%d", inbox_index);
+ ndev = alloc_netdev(sizeof(struct mctp_pcc_ndev), name, NET_NAME_ENUM,
+ mctp_pcc_setup);
+ if (!ndev)
+ return -ENOMEM;
+ mctp_pcc_dev = netdev_priv(ndev);
+ INIT_LIST_HEAD(&mctp_pcc_dev->next);
+ spin_lock_init(&mctp_pcc_dev->lock);
+
+ mctp_pcc_dev->hw_addr.inbox_index = inbox_index;
+ mctp_pcc_dev->hw_addr.outbox_index = outbox_index;
+ mctp_pcc_dev->inbox_client.rx_callback = mctp_pcc_client_rx_callback;
+ mctp_pcc_dev->out_chan =
+ pcc_mbox_request_channel(&mctp_pcc_dev->outbox_client,
+ outbox_index);
+ if (IS_ERR(mctp_pcc_dev->out_chan)) {
+ rc = PTR_ERR(mctp_pcc_dev->out_chan);
+ goto free_netdev;
+ }
+ mctp_pcc_dev->in_chan =
+ pcc_mbox_request_channel(&mctp_pcc_dev->inbox_client,
+ inbox_index);
+ if (IS_ERR(mctp_pcc_dev->in_chan)) {
+ rc = PTR_ERR(mctp_pcc_dev->in_chan);
+ goto cleanup_out_channel;
+ }
+ mctp_pcc_dev->pcc_comm_inbox_addr =
+ devm_ioremap(dev, mctp_pcc_dev->in_chan->shmem_base_addr,
+ mctp_pcc_dev->in_chan->shmem_size);
+ if (!mctp_pcc_dev->pcc_comm_inbox_addr) {
+ rc = -EINVAL;
+ goto cleanup_in_channel;
+ }
+ mctp_pcc_dev->pcc_comm_outbox_addr =
+ devm_ioremap(dev, mctp_pcc_dev->out_chan->shmem_base_addr,
+ mctp_pcc_dev->out_chan->shmem_size);
+ if (!mctp_pcc_dev->pcc_comm_outbox_addr) {
+ rc = -EINVAL;
+ goto cleanup_in_channel;
+ }
+ mctp_pcc_dev->acpi_device = acpi_dev;
+ mctp_pcc_dev->inbox_client.dev = dev;
+ mctp_pcc_dev->outbox_client.dev = dev;
+ mctp_pcc_dev->mdev.dev = ndev;
+ acpi_dev->driver_data = mctp_pcc_dev;
+
+ /* There is no clean way to pass the MTU
+ * to the callback function used for registration,
+ * so set the values ahead of time.
+ */
+ mctp_pcc_mtu = mctp_pcc_dev->out_chan->shmem_size -
+ sizeof(struct mctp_pcc_hdr);
+ ndev->mtu = MCTP_MIN_MTU;
+ ndev->max_mtu = mctp_pcc_mtu;
+ ndev->min_mtu = MCTP_MIN_MTU;
+
+ rc = register_netdev(ndev);
+ if (rc)
+ goto cleanup_in_channel;
+ return 0;
+
+cleanup_in_channel:
+ pcc_mbox_free_channel(mctp_pcc_dev->in_chan);
+cleanup_out_channel:
+ pcc_mbox_free_channel(mctp_pcc_dev->out_chan);
+free_netdev:
+ unregister_netdev(ndev);
+ free_netdev(ndev);
+ return rc;
+}
+
+static void mctp_pcc_driver_remove(struct acpi_device *adev)
+{
+ struct mctp_pcc_ndev *mctp_pcc_ndev = acpi_driver_data(adev);
+
+ pcc_mbox_free_channel(mctp_pcc_ndev->out_chan);
+ pcc_mbox_free_channel(mctp_pcc_ndev->in_chan);
+ mctp_unregister_netdev(mctp_pcc_ndev->mdev.dev);
+}
+
+static const struct acpi_device_id mctp_pcc_device_ids[] = {
+ { "DMT0001", 0},
+ { "", 0},
+};
+
+static struct acpi_driver mctp_pcc_driver = {
+ .name = "mctp_pcc",
+ .class = "Unknown",
+ .ids = mctp_pcc_device_ids,
+ .ops = {
+ .add = mctp_pcc_driver_add,
+ .remove = mctp_pcc_driver_remove,
+ },
+ .owner = THIS_MODULE,
+};
+
+module_acpi_driver(mctp_pcc_driver);
+
+MODULE_DEVICE_TABLE(acpi, mctp_pcc_device_ids);
+
+MODULE_DESCRIPTION("MCTP PCC device");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Adam Young <admiyo@os.amperecomputing.com>");
--
2.34.1