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, 346 insertions, 0 deletions

diff --git a/drivers/net/wwan/iosm/iosm_ipc_imem_ops.c b/drivers/net/wwan/iosm/iosm_ipc_imem_ops.c
new file mode 100644
index 000000000000..46f76e8aae92
--- /dev/null
+++ b/drivers/net/wwan/iosm/iosm_ipc_imem_ops.c
@@ -0,0 +1,346 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020-21 Intel Corporation.
+ */
+
+#include <linux/delay.h>
+
+#include "iosm_ipc_chnl_cfg.h"
+#include "iosm_ipc_imem.h"
+#include "iosm_ipc_imem_ops.h"
+#include "iosm_ipc_port.h"
+#include "iosm_ipc_task_queue.h"
+
+/* Open a packet data online channel between the network layer and CP. */
+int ipc_imem_sys_wwan_open(struct iosm_imem *ipc_imem, int if_id)
+{
+	dev_dbg(ipc_imem->dev, "%s if id: %d",
+		ipc_imem_phase_get_string(ipc_imem->phase), if_id);
+
+	/* The network interface is only supported in the runtime phase. */
+	if (ipc_imem_phase_update(ipc_imem) != IPC_P_RUN) {
+		dev_err(ipc_imem->dev, "net:%d : refused phase %s", if_id,
+			ipc_imem_phase_get_string(ipc_imem->phase));
+		return -EIO;
+	}
+
+	/* check for the interafce id
+	 * if if_id 1 to 8 then create IP MUX channel sessions.
+	 * To start MUX session from 0 as network interface id would start
+	 * from 1 so map it to if_id = if_id - 1
+	 */
+	if (if_id >= IP_MUX_SESSION_START && if_id <= IP_MUX_SESSION_END)
+		return ipc_mux_open_session(ipc_imem->mux, if_id - 1);
+
+	return -EINVAL;
+}
+
+/* Release a net link to CP. */
+void ipc_imem_sys_wwan_close(struct iosm_imem *ipc_imem, int if_id,
+			     int channel_id)
+{
+	if (ipc_imem->mux && if_id >= IP_MUX_SESSION_START &&
+	    if_id <= IP_MUX_SESSION_END)
+		ipc_mux_close_session(ipc_imem->mux, if_id - 1);
+}
+
+/* Tasklet call to do uplink transfer. */
+static int ipc_imem_tq_cdev_write(struct iosm_imem *ipc_imem, int arg,
+				  void *msg, size_t size)
+{
+	ipc_imem->ev_cdev_write_pending = false;
+	ipc_imem_ul_send(ipc_imem);
+
+	return 0;
+}
+
+/* Through tasklet to do sio write. */
+static int ipc_imem_call_cdev_write(struct iosm_imem *ipc_imem)
+{
+	if (ipc_imem->ev_cdev_write_pending)
+		return -1;
+
+	ipc_imem->ev_cdev_write_pending = true;
+
+	return ipc_task_queue_send_task(ipc_imem, ipc_imem_tq_cdev_write, 0,
+					NULL, 0, false);
+}
+
+/* Function for transfer UL data */
+int ipc_imem_sys_wwan_transmit(struct iosm_imem *ipc_imem,
+			       int if_id, int channel_id, struct sk_buff *skb)
+{
+	int ret = -EINVAL;
+
+	if (!ipc_imem || channel_id < 0)
+		goto out;
+
+	/* Is CP Running? */
+	if (ipc_imem->phase != IPC_P_RUN) {
+		dev_dbg(ipc_imem->dev, "phase %s transmit",
+			ipc_imem_phase_get_string(ipc_imem->phase));
+		ret = -EIO;
+		goto out;
+	}
+
+	if (if_id >= IP_MUX_SESSION_START && if_id <= IP_MUX_SESSION_END)
+		/* Route the UL packet through IP MUX Layer */
+		ret = ipc_mux_ul_trigger_encode(ipc_imem->mux,
+						if_id - 1, skb);
+	else
+		dev_err(ipc_imem->dev,
+			"invalid if_id %d: ", if_id);
+out:
+	return ret;
+}
+
+/* Initialize wwan channel */
+void ipc_imem_wwan_channel_init(struct iosm_imem *ipc_imem,
+				enum ipc_mux_protocol mux_type)
+{
+	struct ipc_chnl_cfg chnl_cfg = { 0 };
+
+	ipc_imem->cp_version = ipc_mmio_get_cp_version(ipc_imem->mmio);
+
+	/* If modem version is invalid (0xffffffff), do not initialize WWAN. */
+	if (ipc_imem->cp_version == -1) {
+		dev_err(ipc_imem->dev, "invalid CP version");
+		return;
+	}
+
+	ipc_chnl_cfg_get(&chnl_cfg, ipc_imem->nr_of_channels);
+	ipc_imem_channel_init(ipc_imem, IPC_CTYPE_WWAN, chnl_cfg,
+			      IRQ_MOD_OFF);
+
+	/* WWAN registration. */
+	ipc_imem->wwan = ipc_wwan_init(ipc_imem, ipc_imem->dev);
+	if (!ipc_imem->wwan)
+		dev_err(ipc_imem->dev,
+			"failed to register the ipc_wwan interfaces");
+}
+
+/* Map SKB to DMA for transfer */
+static int ipc_imem_map_skb_to_dma(struct iosm_imem *ipc_imem,
+				   struct sk_buff *skb)
+{
+	struct iosm_pcie *ipc_pcie = ipc_imem->pcie;
+	char *buf = skb->data;
+	int len = skb->len;
+	dma_addr_t mapping;
+	int ret;
+
+	ret = ipc_pcie_addr_map(ipc_pcie, buf, len, &mapping, DMA_TO_DEVICE);
+
+	if (ret)
+		goto err;
+
+	BUILD_BUG_ON(sizeof(*IPC_CB(skb)) > sizeof(skb->cb));
+
+	IPC_CB(skb)->mapping = mapping;
+	IPC_CB(skb)->direction = DMA_TO_DEVICE;
+	IPC_CB(skb)->len = len;
+	IPC_CB(skb)->op_type = (u8)UL_DEFAULT;
+
+err:
+	return ret;
+}
+
+/* return true if channel is ready for use */
+static bool ipc_imem_is_channel_active(struct iosm_imem *ipc_imem,
+				       struct ipc_mem_channel *channel)
+{
+	enum ipc_phase phase;
+
+	/* Update the current operation phase. */
+	phase = ipc_imem->phase;
+
+	/* Select the operation depending on the execution stage. */
+	switch (phase) {
+	case IPC_P_RUN:
+	case IPC_P_PSI:
+	case IPC_P_EBL:
+		break;
+
+	case IPC_P_ROM:
+		/* Prepare the PSI image for the CP ROM driver and
+		 * suspend the flash app.
+		 */
+		if (channel->state != IMEM_CHANNEL_RESERVED) {
+			dev_err(ipc_imem->dev,
+				"ch[%d]:invalid channel state %d,expected %d",
+				channel->channel_id, channel->state,
+				IMEM_CHANNEL_RESERVED);
+			goto channel_unavailable;
+		}
+		goto channel_available;
+
+	default:
+		/* Ignore uplink actions in all other phases. */
+		dev_err(ipc_imem->dev, "ch[%d]: confused phase %d",
+			channel->channel_id, phase);
+		goto channel_unavailable;
+	}
+	/* Check the full availability of the channel. */
+	if (channel->state != IMEM_CHANNEL_ACTIVE) {
+		dev_err(ipc_imem->dev, "ch[%d]: confused channel state %d",
+			channel->channel_id, channel->state);
+		goto channel_unavailable;
+	}
+
+channel_available:
+	return true;
+
+channel_unavailable:
+	return false;
+}
+
+/* Release a sio link to CP. */
+void ipc_imem_sys_cdev_close(struct iosm_cdev *ipc_cdev)
+{
+	struct iosm_imem *ipc_imem = ipc_cdev->ipc_imem;
+	struct ipc_mem_channel *channel = ipc_cdev->channel;
+	enum ipc_phase curr_phase;
+	int status = 0;
+	u32 tail = 0;
+
+	curr_phase = ipc_imem->phase;
+
+	/* If current phase is IPC_P_OFF or SIO ID is -ve then
+	 * channel is already freed. Nothing to do.
+	 */
+	if (curr_phase == IPC_P_OFF) {
+		dev_err(ipc_imem->dev,
+			"nothing to do. Current Phase: %s",
+			ipc_imem_phase_get_string(curr_phase));
+		return;
+	}
+
+	if (channel->state == IMEM_CHANNEL_FREE) {
+		dev_err(ipc_imem->dev, "ch[%d]: invalid channel state %d",
+			channel->channel_id, channel->state);
+		return;
+	}
+
+	/* If there are any pending TDs then wait for Timeout/Completion before
+	 * closing pipe.
+	 */
+	if (channel->ul_pipe.old_tail != channel->ul_pipe.old_head) {
+		ipc_imem->app_notify_ul_pend = 1;
+
+		/* Suspend the user app and wait a certain time for processing
+		 * UL Data.
+		 */
+		status = wait_for_completion_interruptible_timeout
+			 (&ipc_imem->ul_pend_sem,
+			  msecs_to_jiffies(IPC_PEND_DATA_TIMEOUT));
+		if (status == 0) {
+			dev_dbg(ipc_imem->dev,
+				"Pend data Timeout UL-Pipe:%d Head:%d Tail:%d",
+				channel->ul_pipe.pipe_nr,
+				channel->ul_pipe.old_head,
+				channel->ul_pipe.old_tail);
+		}
+
+		ipc_imem->app_notify_ul_pend = 0;
+	}
+
+	/* If there are any pending TDs then wait for Timeout/Completion before
+	 * closing pipe.
+	 */
+	ipc_protocol_get_head_tail_index(ipc_imem->ipc_protocol,
+					 &channel->dl_pipe, NULL, &tail);
+
+	if (tail != channel->dl_pipe.old_tail) {
+		ipc_imem->app_notify_dl_pend = 1;
+
+		/* Suspend the user app and wait a certain time for processing
+		 * DL Data.
+		 */
+		status = wait_for_completion_interruptible_timeout
+			 (&ipc_imem->dl_pend_sem,
+			  msecs_to_jiffies(IPC_PEND_DATA_TIMEOUT));
+		if (status == 0) {
+			dev_dbg(ipc_imem->dev,
+				"Pend data Timeout DL-Pipe:%d Head:%d Tail:%d",
+				channel->dl_pipe.pipe_nr,
+				channel->dl_pipe.old_head,
+				channel->dl_pipe.old_tail);
+		}
+
+		ipc_imem->app_notify_dl_pend = 0;
+	}
+
+	/* Due to wait for completion in messages, there is a small window
+	 * between closing the pipe and updating the channel is closed. In this
+	 * small window there could be HP update from Host Driver. Hence update
+	 * the channel state as CLOSING to aviod unnecessary interrupt
+	 * towards CP.
+	 */
+	channel->state = IMEM_CHANNEL_CLOSING;
+
+	ipc_imem_pipe_close(ipc_imem, &channel->ul_pipe);
+	ipc_imem_pipe_close(ipc_imem, &channel->dl_pipe);
+
+	ipc_imem_channel_free(channel);
+}
+
+/* Open a PORT link to CP and return the channel */
+struct ipc_mem_channel *ipc_imem_sys_port_open(struct iosm_imem *ipc_imem,
+					       int chl_id, int hp_id)
+{
+	struct ipc_mem_channel *channel;
+	int ch_id;
+
+	/* The PORT interface is only supported in the runtime phase. */
+	if (ipc_imem_phase_update(ipc_imem) != IPC_P_RUN) {
+		dev_err(ipc_imem->dev, "PORT open refused, phase %s",
+			ipc_imem_phase_get_string(ipc_imem->phase));
+		return NULL;
+	}
+
+	ch_id = ipc_imem_channel_alloc(ipc_imem, chl_id, IPC_CTYPE_CTRL);
+
+	if (ch_id < 0) {
+		dev_err(ipc_imem->dev, "reservation of an PORT chnl id failed");
+		return NULL;
+	}
+
+	channel = ipc_imem_channel_open(ipc_imem, ch_id, hp_id);
+
+	if (!channel) {
+		dev_err(ipc_imem->dev, "PORT channel id open failed");
+		return NULL;
+	}
+
+	return channel;
+}
+
+/* transfer skb to modem */
+int ipc_imem_sys_cdev_write(struct iosm_cdev *ipc_cdev, struct sk_buff *skb)
+{
+	struct ipc_mem_channel *channel = ipc_cdev->channel;
+	struct iosm_imem *ipc_imem = ipc_cdev->ipc_imem;
+	int ret = -EIO;
+
+	if (!ipc_imem_is_channel_active(ipc_imem, channel) ||
+	    ipc_imem->phase == IPC_P_OFF_REQ)
+		goto out;
+
+	ret = ipc_imem_map_skb_to_dma(ipc_imem, skb);
+
+	if (ret)
+		goto out;
+
+	/* Add skb to the uplink skbuf accumulator. */
+	skb_queue_tail(&channel->ul_list, skb);
+
+	ret = ipc_imem_call_cdev_write(ipc_imem);
+
+	if (ret) {
+		skb_dequeue_tail(&channel->ul_list);
+		dev_err(ipc_cdev->dev, "channel id[%d] write failed\n",
+			ipc_cdev->channel->channel_id);
+	}
+out:
+	return ret;
+}