Merge branch 'iosm-driver'

M Chetan Kumar says:

====================
net: iosm: PCIe Driver for Intel M.2 Modem

The IOSM (IPC over Shared Memory) driver is a PCIe host driver implemented
for linux or chrome platform for data exchange over PCIe interface between
Host platform & Intel M.2 Modem. The driver exposes interface conforming to
the MBIM protocol. Any front end application ( eg: Modem Manager) could
easily manage the MBIM interface to enable data communication towards WWAN.

Intel M.2 modem uses 2 BAR regions. The first region is dedicated to Doorbell
register for IRQs and the second region is used as scratchpad area for book
keeping modem execution stage details along with host system shared memory
region context details. The upper edge of the driver exposes the control and
data channels for user space application interaction. At lower edge these data
and control channels are associated to pipes. The pipes are lowest level
interfaces used over PCIe as a logical channel for message exchange. A single
channel maps to UL and DL pipe and are initialized on device open.

On UL path, driver copies application sent data to SKBs associate it with
transfer descriptor and puts it on to ring buffer for DMA transfer. Once
information has been updated in shared memory region, host gives a Doorbell
to modem to perform DMA and modem uses MSI to communicate back to host.
For receiving data in DL path, SKBs are pre-allocated during pipe open and
transfer descriptors are given to modem for DMA transfer.

The driver exposes two types of ports, namely "wwan0mbim0", a char device node
which is used for MBIM control operation and "wwan0-x",(x = 0,1,2..7) network
interfaces for IP data communication.
1) MBIM Control Interface:
This node exposes an interface between modem and application using char device
exposed by "IOSM" driver to establish and manage the MBIM data communication
with PCIe based Intel M.2 Modems.

2) MBIM Data Interface:
The IOSM driver exposes IP link interface "wwan0-x" of type "wwan" for IP traffic.
Iproute network utility is used for creating "wwan0-x" network interface and for
associating it with MBIM IP session. The Driver supports upto 8 IP sessions for
simultaneous IP communication.

This applies on top of WWAN core rtnetlink series posted here:
https://lore.kernel.org/netdev/1623486057-13075-1-git-send-email-loic.poulain@linaro.org/

Also driver has been compiled and tested on top of netdev net-next tree.
https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 455 insertions, 0 deletions

diff --git a/drivers/net/wwan/iosm/iosm_ipc_mux.c b/drivers/net/wwan/iosm/iosm_ipc_mux.c
new file mode 100644
index 000000000000..c1c77ce699da
--- /dev/null
+++ b/drivers/net/wwan/iosm/iosm_ipc_mux.c
@@ -0,0 +1,455 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020-21 Intel Corporation.
+ */
+
+#include "iosm_ipc_mux_codec.h"
+
+/* At the begin of the runtime phase the IP MUX channel shall created. */
+static int ipc_mux_channel_create(struct iosm_mux *ipc_mux)
+{
+	int channel_id;
+
+	channel_id = ipc_imem_channel_alloc(ipc_mux->imem, ipc_mux->instance_id,
+					    IPC_CTYPE_WWAN);
+
+	if (channel_id < 0) {
+		dev_err(ipc_mux->dev,
+			"allocation of the MUX channel id failed");
+		ipc_mux->state = MUX_S_ERROR;
+		ipc_mux->event = MUX_E_NOT_APPLICABLE;
+		goto no_channel;
+	}
+
+	/* Establish the MUX channel in blocking mode. */
+	ipc_mux->channel = ipc_imem_channel_open(ipc_mux->imem, channel_id,
+						 IPC_HP_NET_CHANNEL_INIT);
+
+	if (!ipc_mux->channel) {
+		dev_err(ipc_mux->dev, "ipc_imem_channel_open failed");
+		ipc_mux->state = MUX_S_ERROR;
+		ipc_mux->event = MUX_E_NOT_APPLICABLE;
+		return -ENODEV; /* MUX channel is not available. */
+	}
+
+	/* Define the MUX active state properties. */
+	ipc_mux->state = MUX_S_ACTIVE;
+	ipc_mux->event = MUX_E_NO_ORDERS;
+
+no_channel:
+	return channel_id;
+}
+
+/* Reset the session/if id state. */
+static void ipc_mux_session_free(struct iosm_mux *ipc_mux, int if_id)
+{
+	struct mux_session *if_entry;
+
+	if_entry = &ipc_mux->session[if_id];
+	/* Reset the session state. */
+	if_entry->wwan = NULL;
+}
+
+/* Create and send the session open command. */
+static struct mux_cmd_open_session_resp *
+ipc_mux_session_open_send(struct iosm_mux *ipc_mux, int if_id)
+{
+	struct mux_cmd_open_session_resp *open_session_resp;
+	struct mux_acb *acb = &ipc_mux->acb;
+	union mux_cmd_param param;
+
+	/* open_session commands to one ACB and start transmission. */
+	param.open_session.flow_ctrl = 0;
+	param.open_session.ipv4v6_hints = 0;
+	param.open_session.reserved2 = 0;
+	param.open_session.dl_head_pad_len = cpu_to_le32(IPC_MEM_DL_ETH_OFFSET);
+
+	/* Finish and transfer ACB. The user thread is suspended.
+	 * It is a blocking function call, until CP responds or timeout.
+	 */
+	acb->wanted_response = MUX_CMD_OPEN_SESSION_RESP;
+	if (ipc_mux_dl_acb_send_cmds(ipc_mux, MUX_CMD_OPEN_SESSION, if_id, 0,
+				     &param, sizeof(param.open_session), true,
+				 false) ||
+	    acb->got_response != MUX_CMD_OPEN_SESSION_RESP) {
+		dev_err(ipc_mux->dev, "if_id %d: OPEN_SESSION send failed",
+			if_id);
+		return NULL;
+	}
+
+	open_session_resp = &ipc_mux->acb.got_param.open_session_resp;
+	if (open_session_resp->response != cpu_to_le32(MUX_CMD_RESP_SUCCESS)) {
+		dev_err(ipc_mux->dev,
+			"if_id %d,session open failed,response=%d", if_id,
+			open_session_resp->response);
+		return NULL;
+	}
+
+	return open_session_resp;
+}
+
+/* Open the first IP session. */
+static bool ipc_mux_session_open(struct iosm_mux *ipc_mux,
+				 struct mux_session_open *session_open)
+{
+	struct mux_cmd_open_session_resp *open_session_resp;
+	int if_id;
+
+	/* Search for a free session interface id. */
+	if_id = le32_to_cpu(session_open->if_id);
+	if (if_id < 0 || if_id >= ipc_mux->nr_sessions) {
+		dev_err(ipc_mux->dev, "invalid interface id=%d", if_id);
+		return false;
+	}
+
+	/* Create and send the session open command.
+	 * It is a blocking function call, until CP responds or timeout.
+	 */
+	open_session_resp = ipc_mux_session_open_send(ipc_mux, if_id);
+	if (!open_session_resp) {
+		ipc_mux_session_free(ipc_mux, if_id);
+		session_open->if_id = cpu_to_le32(-1);
+		return false;
+	}
+
+	/* Initialize the uplink skb accumulator. */
+	skb_queue_head_init(&ipc_mux->session[if_id].ul_list);
+
+	ipc_mux->session[if_id].dl_head_pad_len = IPC_MEM_DL_ETH_OFFSET;
+	ipc_mux->session[if_id].ul_head_pad_len =
+		le32_to_cpu(open_session_resp->ul_head_pad_len);
+	ipc_mux->session[if_id].wwan = ipc_mux->wwan;
+
+	/* Reset the flow ctrl stats of the session */
+	ipc_mux->session[if_id].flow_ctl_en_cnt = 0;
+	ipc_mux->session[if_id].flow_ctl_dis_cnt = 0;
+	ipc_mux->session[if_id].ul_flow_credits = 0;
+	ipc_mux->session[if_id].net_tx_stop = false;
+	ipc_mux->session[if_id].flow_ctl_mask = 0;
+
+	/* Save and return the assigned if id. */
+	session_open->if_id = cpu_to_le32(if_id);
+
+	return true;
+}
+
+/* Free pending session UL packet. */
+static void ipc_mux_session_reset(struct iosm_mux *ipc_mux, int if_id)
+{
+	/* Reset the session/if id state. */
+	ipc_mux_session_free(ipc_mux, if_id);
+
+	/* Empty the uplink skb accumulator. */
+	skb_queue_purge(&ipc_mux->session[if_id].ul_list);
+}
+
+static void ipc_mux_session_close(struct iosm_mux *ipc_mux,
+				  struct mux_session_close *msg)
+{
+	int if_id;
+
+	/* Copy the session interface id. */
+	if_id = le32_to_cpu(msg->if_id);
+
+	if (if_id < 0 || if_id >= ipc_mux->nr_sessions) {
+		dev_err(ipc_mux->dev, "invalid session id %d", if_id);
+		return;
+	}
+
+	/* Create and send the session close command.
+	 * It is a blocking function call, until CP responds or timeout.
+	 */
+	if (ipc_mux_dl_acb_send_cmds(ipc_mux, MUX_CMD_CLOSE_SESSION, if_id, 0,
+				     NULL, 0, true, false))
+		dev_err(ipc_mux->dev, "if_id %d: CLOSE_SESSION send failed",
+			if_id);
+
+	/* Reset the flow ctrl stats of the session */
+	ipc_mux->session[if_id].flow_ctl_en_cnt = 0;
+	ipc_mux->session[if_id].flow_ctl_dis_cnt = 0;
+	ipc_mux->session[if_id].flow_ctl_mask = 0;
+
+	ipc_mux_session_reset(ipc_mux, if_id);
+}
+
+static void ipc_mux_channel_close(struct iosm_mux *ipc_mux,
+				  struct mux_channel_close *channel_close_p)
+{
+	int i;
+
+	/* Free pending session UL packet. */
+	for (i = 0; i < ipc_mux->nr_sessions; i++)
+		if (ipc_mux->session[i].wwan)
+			ipc_mux_session_reset(ipc_mux, i);
+
+	ipc_imem_channel_close(ipc_mux->imem, ipc_mux->channel_id);
+
+	/* Reset the MUX object. */
+	ipc_mux->state = MUX_S_INACTIVE;
+	ipc_mux->event = MUX_E_INACTIVE;
+}
+
+/* CP has interrupted AP. If AP is in IP MUX mode, execute the pending ops. */
+static int ipc_mux_schedule(struct iosm_mux *ipc_mux, union mux_msg *msg)
+{
+	enum mux_event order;
+	bool success;
+	int ret = -EIO;
+
+	if (!ipc_mux->initialized) {
+		ret = -EAGAIN;
+		goto out;
+	}
+
+	order = msg->common.event;
+
+	switch (ipc_mux->state) {
+	case MUX_S_INACTIVE:
+		if (order != MUX_E_MUX_SESSION_OPEN)
+			goto out; /* Wait for the request to open a session */
+
+		if (ipc_mux->event == MUX_E_INACTIVE)
+			/* Establish the MUX channel and the new state. */
+			ipc_mux->channel_id = ipc_mux_channel_create(ipc_mux);
+
+		if (ipc_mux->state != MUX_S_ACTIVE) {
+			ret = ipc_mux->channel_id; /* Missing the MUX channel */
+			goto out;
+		}
+
+		/* Disable the TD update timer and open the first IP session. */
+		ipc_imem_td_update_timer_suspend(ipc_mux->imem, true);
+		ipc_mux->event = MUX_E_MUX_SESSION_OPEN;
+		success = ipc_mux_session_open(ipc_mux, &msg->session_open);
+
+		ipc_imem_td_update_timer_suspend(ipc_mux->imem, false);
+		if (success)
+			ret = ipc_mux->channel_id;
+		goto out;
+
+	case MUX_S_ACTIVE:
+		switch (order) {
+		case MUX_E_MUX_SESSION_OPEN:
+			/* Disable the TD update timer and open a session */
+			ipc_imem_td_update_timer_suspend(ipc_mux->imem, true);
+			ipc_mux->event = MUX_E_MUX_SESSION_OPEN;
+			success = ipc_mux_session_open(ipc_mux,
+						       &msg->session_open);
+			ipc_imem_td_update_timer_suspend(ipc_mux->imem, false);
+			if (success)
+				ret = ipc_mux->channel_id;
+			goto out;
+
+		case MUX_E_MUX_SESSION_CLOSE:
+			/* Release an IP session. */
+			ipc_mux->event = MUX_E_MUX_SESSION_CLOSE;
+			ipc_mux_session_close(ipc_mux, &msg->session_close);
+			ret = ipc_mux->channel_id;
+			goto out;
+
+		case MUX_E_MUX_CHANNEL_CLOSE:
+			/* Close the MUX channel pipes. */
+			ipc_mux->event = MUX_E_MUX_CHANNEL_CLOSE;
+			ipc_mux_channel_close(ipc_mux, &msg->channel_close);
+			ret = ipc_mux->channel_id;
+			goto out;
+
+		default:
+			/* Invalid order. */
+			goto out;
+		}
+
+	default:
+		dev_err(ipc_mux->dev,
+			"unexpected MUX transition: state=%d, event=%d",
+			ipc_mux->state, ipc_mux->event);
+	}
+out:
+	return ret;
+}
+
+struct iosm_mux *ipc_mux_init(struct ipc_mux_config *mux_cfg,
+			      struct iosm_imem *imem)
+{
+	struct iosm_mux *ipc_mux = kzalloc(sizeof(*ipc_mux), GFP_KERNEL);
+	int i, ul_tds, ul_td_size;
+	struct sk_buff_head *free_list;
+	struct sk_buff *skb;
+
+	if (!ipc_mux)
+		return NULL;
+
+	ipc_mux->protocol = mux_cfg->protocol;
+	ipc_mux->ul_flow = mux_cfg->ul_flow;
+	ipc_mux->nr_sessions = mux_cfg->nr_sessions;
+	ipc_mux->instance_id = mux_cfg->instance_id;
+	ipc_mux->wwan_q_offset = 0;
+
+	ipc_mux->pcie = imem->pcie;
+	ipc_mux->imem = imem;
+	ipc_mux->ipc_protocol = imem->ipc_protocol;
+	ipc_mux->dev = imem->dev;
+	ipc_mux->wwan = imem->wwan;
+
+	/* Get the reference to the UL ADB list. */
+	free_list = &ipc_mux->ul_adb.free_list;
+
+	/* Initialize the list with free ADB. */
+	skb_queue_head_init(free_list);
+
+	ul_td_size = IPC_MEM_MAX_DL_MUX_LITE_BUF_SIZE;
+
+	ul_tds = IPC_MEM_MAX_TDS_MUX_LITE_UL;
+
+	ipc_mux->ul_adb.dest_skb = NULL;
+
+	ipc_mux->initialized = true;
+	ipc_mux->adb_prep_ongoing = false;
+	ipc_mux->size_needed = 0;
+	ipc_mux->ul_data_pend_bytes = 0;
+	ipc_mux->state = MUX_S_INACTIVE;
+	ipc_mux->ev_mux_net_transmit_pending = false;
+	ipc_mux->tx_transaction_id = 0;
+	ipc_mux->rr_next_session = 0;
+	ipc_mux->event = MUX_E_INACTIVE;
+	ipc_mux->channel_id = -1;
+	ipc_mux->channel = NULL;
+
+	/* Allocate the list of UL ADB. */
+	for (i = 0; i < ul_tds; i++) {
+		dma_addr_t mapping;
+
+		skb = ipc_pcie_alloc_skb(ipc_mux->pcie, ul_td_size, GFP_ATOMIC,
+					 &mapping, DMA_TO_DEVICE, 0);
+		if (!skb) {
+			ipc_mux_deinit(ipc_mux);
+			return NULL;
+		}
+		/* Extend the UL ADB list. */
+		skb_queue_tail(free_list, skb);
+	}
+
+	return ipc_mux;
+}
+
+/* Informs the network stack to restart transmission for all opened session if
+ * Flow Control is not ON for that session.
+ */
+static void ipc_mux_restart_tx_for_all_sessions(struct iosm_mux *ipc_mux)
+{
+	struct mux_session *session;
+	int idx;
+
+	for (idx = 0; idx < ipc_mux->nr_sessions; idx++) {
+		session = &ipc_mux->session[idx];
+
+		if (!session->wwan)
+			continue;
+
+		/* If flow control of the session is OFF and if there was tx
+		 * stop then restart. Inform the network interface to restart
+		 * sending data.
+		 */
+		if (session->flow_ctl_mask == 0) {
+			session->net_tx_stop = false;
+			ipc_mux_netif_tx_flowctrl(session, idx, false);
+		}
+	}
+}
+
+/* Informs the network stack to stop sending further pkt for all opened
+ * sessions
+ */
+static void ipc_mux_stop_netif_for_all_sessions(struct iosm_mux *ipc_mux)
+{
+	struct mux_session *session;
+	int idx;
+
+	for (idx = 0; idx < ipc_mux->nr_sessions; idx++) {
+		session = &ipc_mux->session[idx];
+
+		if (!session->wwan)
+			continue;
+
+		ipc_mux_netif_tx_flowctrl(session, session->if_id, true);
+	}
+}
+
+void ipc_mux_check_n_restart_tx(struct iosm_mux *ipc_mux)
+{
+	if (ipc_mux->ul_flow == MUX_UL) {
+		int low_thresh = IPC_MEM_MUX_UL_FLOWCTRL_LOW_B;
+
+		if (ipc_mux->ul_data_pend_bytes < low_thresh)
+			ipc_mux_restart_tx_for_all_sessions(ipc_mux);
+	}
+}
+
+int ipc_mux_get_max_sessions(struct iosm_mux *ipc_mux)
+{
+	return ipc_mux ? ipc_mux->nr_sessions : -EFAULT;
+}
+
+enum ipc_mux_protocol ipc_mux_get_active_protocol(struct iosm_mux *ipc_mux)
+{
+	return ipc_mux ? ipc_mux->protocol : MUX_UNKNOWN;
+}
+
+int ipc_mux_open_session(struct iosm_mux *ipc_mux, int session_nr)
+{
+	struct mux_session_open *session_open;
+	union mux_msg mux_msg;
+
+	session_open = &mux_msg.session_open;
+	session_open->event = MUX_E_MUX_SESSION_OPEN;
+
+	session_open->if_id = cpu_to_le32(session_nr);
+	ipc_mux->session[session_nr].flags |= IPC_MEM_WWAN_MUX;
+	return ipc_mux_schedule(ipc_mux, &mux_msg);
+}
+
+int ipc_mux_close_session(struct iosm_mux *ipc_mux, int session_nr)
+{
+	struct mux_session_close *session_close;
+	union mux_msg mux_msg;
+	int ret_val;
+
+	session_close = &mux_msg.session_close;
+	session_close->event = MUX_E_MUX_SESSION_CLOSE;
+
+	session_close->if_id = cpu_to_le32(session_nr);
+	ret_val = ipc_mux_schedule(ipc_mux, &mux_msg);
+	ipc_mux->session[session_nr].flags &= ~IPC_MEM_WWAN_MUX;
+
+	return ret_val;
+}
+
+void ipc_mux_deinit(struct iosm_mux *ipc_mux)
+{
+	struct mux_channel_close *channel_close;
+	struct sk_buff_head *free_list;
+	union mux_msg mux_msg;
+	struct sk_buff *skb;
+
+	if (!ipc_mux->initialized)
+		return;
+	ipc_mux_stop_netif_for_all_sessions(ipc_mux);
+
+	channel_close = &mux_msg.channel_close;
+	channel_close->event = MUX_E_MUX_CHANNEL_CLOSE;
+	ipc_mux_schedule(ipc_mux, &mux_msg);
+
+	/* Empty the ADB free list. */
+	free_list = &ipc_mux->ul_adb.free_list;
+
+	/* Remove from the head of the downlink queue. */
+	while ((skb = skb_dequeue(free_list)))
+		ipc_pcie_kfree_skb(ipc_mux->pcie, skb);
+
+	if (ipc_mux->channel) {
+		ipc_mux->channel->ul_pipe.is_open = false;
+		ipc_mux->channel->dl_pipe.is_open = false;
+	}
+
+	kfree(ipc_mux);
+}