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, 552 insertions, 0 deletions

diff --git a/drivers/net/wwan/iosm/iosm_ipc_protocol_ops.c b/drivers/net/wwan/iosm/iosm_ipc_protocol_ops.c
new file mode 100644
index 000000000000..91109e27efd3
--- /dev/null
+++ b/drivers/net/wwan/iosm/iosm_ipc_protocol_ops.c
@@ -0,0 +1,552 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020-21 Intel Corporation.
+ */
+
+#include "iosm_ipc_protocol.h"
+#include "iosm_ipc_protocol_ops.h"
+
+/* Get the next free message element.*/
+static union ipc_mem_msg_entry *
+ipc_protocol_free_msg_get(struct iosm_protocol *ipc_protocol, int *index)
+{
+	u32 head = le32_to_cpu(ipc_protocol->p_ap_shm->msg_head);
+	u32 new_head = (head + 1) % IPC_MEM_MSG_ENTRIES;
+	union ipc_mem_msg_entry *msg;
+
+	if (new_head == le32_to_cpu(ipc_protocol->p_ap_shm->msg_tail)) {
+		dev_err(ipc_protocol->dev, "message ring is full");
+		return NULL;
+	}
+
+	/* Get the pointer to the next free message element,
+	 * reset the fields and mark is as invalid.
+	 */
+	msg = &ipc_protocol->p_ap_shm->msg_ring[head];
+	memset(msg, 0, sizeof(*msg));
+
+	/* return index in message ring */
+	*index = head;
+
+	return msg;
+}
+
+/* Updates the message ring Head pointer */
+void ipc_protocol_msg_hp_update(struct iosm_imem *ipc_imem)
+{
+	struct iosm_protocol *ipc_protocol = ipc_imem->ipc_protocol;
+	u32 head = le32_to_cpu(ipc_protocol->p_ap_shm->msg_head);
+	u32 new_head = (head + 1) % IPC_MEM_MSG_ENTRIES;
+
+	/* Update head pointer and fire doorbell. */
+	ipc_protocol->p_ap_shm->msg_head = cpu_to_le32(new_head);
+	ipc_protocol->old_msg_tail =
+		le32_to_cpu(ipc_protocol->p_ap_shm->msg_tail);
+
+	ipc_pm_signal_hpda_doorbell(&ipc_protocol->pm, IPC_HP_MR, false);
+}
+
+/* Allocate and prepare a OPEN_PIPE message.
+ * This also allocates the memory for the new TDR structure and
+ * updates the pipe structure referenced in the preparation arguments.
+ */
+static int ipc_protocol_msg_prepipe_open(struct iosm_protocol *ipc_protocol,
+					 union ipc_msg_prep_args *args)
+{
+	int index;
+	union ipc_mem_msg_entry *msg =
+		ipc_protocol_free_msg_get(ipc_protocol, &index);
+	struct ipc_pipe *pipe = args->pipe_open.pipe;
+	struct ipc_protocol_td *tdr;
+	struct sk_buff **skbr;
+
+	if (!msg) {
+		dev_err(ipc_protocol->dev, "failed to get free message");
+		return -EIO;
+	}
+
+	/* Allocate the skbuf elements for the skbuf which are on the way.
+	 * SKB ring is internal memory allocation for driver. No need to
+	 * re-calculate the start and end addresses.
+	 */
+	skbr = kcalloc(pipe->nr_of_entries, sizeof(*skbr), GFP_ATOMIC);
+	if (!skbr)
+		return -ENOMEM;
+
+	/* Allocate the transfer descriptors for the pipe. */
+	tdr = pci_alloc_consistent(ipc_protocol->pcie->pci,
+				   pipe->nr_of_entries * sizeof(*tdr),
+				   &pipe->phy_tdr_start);
+	if (!tdr) {
+		kfree(skbr);
+		dev_err(ipc_protocol->dev, "tdr alloc error");
+		return -ENOMEM;
+	}
+
+	pipe->max_nr_of_queued_entries = pipe->nr_of_entries - 1;
+	pipe->nr_of_queued_entries = 0;
+	pipe->tdr_start = tdr;
+	pipe->skbr_start = skbr;
+	pipe->old_tail = 0;
+
+	ipc_protocol->p_ap_shm->head_array[pipe->pipe_nr] = 0;
+
+	msg->open_pipe.type_of_message = IPC_MEM_MSG_OPEN_PIPE;
+	msg->open_pipe.pipe_nr = pipe->pipe_nr;
+	msg->open_pipe.tdr_addr = cpu_to_le64(pipe->phy_tdr_start);
+	msg->open_pipe.tdr_entries = cpu_to_le16(pipe->nr_of_entries);
+	msg->open_pipe.accumulation_backoff =
+				cpu_to_le32(pipe->accumulation_backoff);
+	msg->open_pipe.irq_vector = cpu_to_le32(pipe->irq);
+
+	return index;
+}
+
+static int ipc_protocol_msg_prepipe_close(struct iosm_protocol *ipc_protocol,
+					  union ipc_msg_prep_args *args)
+{
+	int index = -1;
+	union ipc_mem_msg_entry *msg =
+		ipc_protocol_free_msg_get(ipc_protocol, &index);
+	struct ipc_pipe *pipe = args->pipe_close.pipe;
+
+	if (!msg)
+		return -EIO;
+
+	msg->close_pipe.type_of_message = IPC_MEM_MSG_CLOSE_PIPE;
+	msg->close_pipe.pipe_nr = pipe->pipe_nr;
+
+	dev_dbg(ipc_protocol->dev, "IPC_MEM_MSG_CLOSE_PIPE(pipe_nr=%d)",
+		msg->close_pipe.pipe_nr);
+
+	return index;
+}
+
+static int ipc_protocol_msg_prep_sleep(struct iosm_protocol *ipc_protocol,
+				       union ipc_msg_prep_args *args)
+{
+	int index = -1;
+	union ipc_mem_msg_entry *msg =
+		ipc_protocol_free_msg_get(ipc_protocol, &index);
+
+	if (!msg) {
+		dev_err(ipc_protocol->dev, "failed to get free message");
+		return -EIO;
+	}
+
+	/* Prepare and send the host sleep message to CP to enter or exit D3. */
+	msg->host_sleep.type_of_message = IPC_MEM_MSG_SLEEP;
+	msg->host_sleep.target = args->sleep.target; /* 0=host, 1=device */
+
+	/* state; 0=enter, 1=exit 2=enter w/o protocol */
+	msg->host_sleep.state = args->sleep.state;
+
+	dev_dbg(ipc_protocol->dev, "IPC_MEM_MSG_SLEEP(target=%d; state=%d)",
+		msg->host_sleep.target, msg->host_sleep.state);
+
+	return index;
+}
+
+static int ipc_protocol_msg_prep_feature_set(struct iosm_protocol *ipc_protocol,
+					     union ipc_msg_prep_args *args)
+{
+	int index = -1;
+	union ipc_mem_msg_entry *msg =
+		ipc_protocol_free_msg_get(ipc_protocol, &index);
+
+	if (!msg) {
+		dev_err(ipc_protocol->dev, "failed to get free message");
+		return -EIO;
+	}
+
+	msg->feature_set.type_of_message = IPC_MEM_MSG_FEATURE_SET;
+	msg->feature_set.reset_enable = args->feature_set.reset_enable <<
+					RESET_BIT;
+
+	dev_dbg(ipc_protocol->dev, "IPC_MEM_MSG_FEATURE_SET(reset_enable=%d)",
+		msg->feature_set.reset_enable >> RESET_BIT);
+
+	return index;
+}
+
+/* Processes the message consumed by CP. */
+bool ipc_protocol_msg_process(struct iosm_imem *ipc_imem, int irq)
+{
+	struct iosm_protocol *ipc_protocol = ipc_imem->ipc_protocol;
+	struct ipc_rsp **rsp_ring = ipc_protocol->rsp_ring;
+	bool msg_processed = false;
+	u32 i;
+
+	if (le32_to_cpu(ipc_protocol->p_ap_shm->msg_tail) >=
+			IPC_MEM_MSG_ENTRIES) {
+		dev_err(ipc_protocol->dev, "msg_tail out of range: %d",
+			le32_to_cpu(ipc_protocol->p_ap_shm->msg_tail));
+		return msg_processed;
+	}
+
+	if (irq != IMEM_IRQ_DONT_CARE &&
+	    irq != ipc_protocol->p_ap_shm->ci.msg_irq_vector)
+		return msg_processed;
+
+	for (i = ipc_protocol->old_msg_tail;
+	     i != le32_to_cpu(ipc_protocol->p_ap_shm->msg_tail);
+	     i = (i + 1) % IPC_MEM_MSG_ENTRIES) {
+		union ipc_mem_msg_entry *msg =
+			&ipc_protocol->p_ap_shm->msg_ring[i];
+
+		dev_dbg(ipc_protocol->dev, "msg[%d]: type=%u status=%d", i,
+			msg->common.type_of_message,
+			msg->common.completion_status);
+
+		/* Update response with status and wake up waiting requestor */
+		if (rsp_ring[i]) {
+			rsp_ring[i]->status =
+				le32_to_cpu(msg->common.completion_status);
+			complete(&rsp_ring[i]->completion);
+			rsp_ring[i] = NULL;
+		}
+		msg_processed = true;
+	}
+
+	ipc_protocol->old_msg_tail = i;
+	return msg_processed;
+}
+
+/* Sends data from UL list to CP for the provided pipe by updating the Head
+ * pointer of given pipe.
+ */
+bool ipc_protocol_ul_td_send(struct iosm_protocol *ipc_protocol,
+			     struct ipc_pipe *pipe,
+			     struct sk_buff_head *p_ul_list)
+{
+	struct ipc_protocol_td *td;
+	bool hpda_pending = false;
+	struct sk_buff *skb;
+	s32 free_elements;
+	u32 head;
+	u32 tail;
+
+	if (!ipc_protocol->p_ap_shm) {
+		dev_err(ipc_protocol->dev, "driver is not initialized");
+		return false;
+	}
+
+	/* Get head and tail of the td list and calculate
+	 * the number of free elements.
+	 */
+	head = le32_to_cpu(ipc_protocol->p_ap_shm->head_array[pipe->pipe_nr]);
+	tail = pipe->old_tail;
+
+	while (!skb_queue_empty(p_ul_list)) {
+		if (head < tail)
+			free_elements = tail - head - 1;
+		else
+			free_elements =
+				pipe->nr_of_entries - head + ((s32)tail - 1);
+
+		if (free_elements <= 0) {
+			dev_dbg(ipc_protocol->dev,
+				"no free td elements for UL pipe %d",
+				pipe->pipe_nr);
+			break;
+		}
+
+		/* Get the td address. */
+		td = &pipe->tdr_start[head];
+
+		/* Take the first element of the uplink list and add it
+		 * to the td list.
+		 */
+		skb = skb_dequeue(p_ul_list);
+		if (WARN_ON(!skb))
+			break;
+
+		/* Save the reference to the uplink skbuf. */
+		pipe->skbr_start[head] = skb;
+
+		td->buffer.address = IPC_CB(skb)->mapping;
+		td->scs = cpu_to_le32(skb->len) & cpu_to_le32(SIZE_MASK);
+		td->next = 0;
+
+		pipe->nr_of_queued_entries++;
+
+		/* Calculate the new head and save it. */
+		head++;
+		if (head >= pipe->nr_of_entries)
+			head = 0;
+
+		ipc_protocol->p_ap_shm->head_array[pipe->pipe_nr] =
+			cpu_to_le32(head);
+	}
+
+	if (pipe->old_head != head) {
+		dev_dbg(ipc_protocol->dev, "New UL TDs Pipe:%d", pipe->pipe_nr);
+
+		pipe->old_head = head;
+		/* Trigger doorbell because of pending UL packets. */
+		hpda_pending = true;
+	}
+
+	return hpda_pending;
+}
+
+/* Checks for Tail pointer update from CP and returns the data as SKB. */
+struct sk_buff *ipc_protocol_ul_td_process(struct iosm_protocol *ipc_protocol,
+					   struct ipc_pipe *pipe)
+{
+	struct ipc_protocol_td *p_td = &pipe->tdr_start[pipe->old_tail];
+	struct sk_buff *skb = pipe->skbr_start[pipe->old_tail];
+
+	pipe->nr_of_queued_entries--;
+	pipe->old_tail++;
+	if (pipe->old_tail >= pipe->nr_of_entries)
+		pipe->old_tail = 0;
+
+	if (!p_td->buffer.address) {
+		dev_err(ipc_protocol->dev, "Td buffer address is NULL");
+		return NULL;
+	}
+
+	if (p_td->buffer.address != IPC_CB(skb)->mapping) {
+		dev_err(ipc_protocol->dev,
+			"pipe %d: invalid buf_addr or skb_data",
+			pipe->pipe_nr);
+		return NULL;
+	}
+
+	return skb;
+}
+
+/* Allocates an SKB for CP to send data and updates the Head Pointer
+ * of the given Pipe#.
+ */
+bool ipc_protocol_dl_td_prepare(struct iosm_protocol *ipc_protocol,
+				struct ipc_pipe *pipe)
+{
+	struct ipc_protocol_td *td;
+	dma_addr_t mapping = 0;
+	u32 head, new_head;
+	struct sk_buff *skb;
+	u32 tail;
+
+	/* Get head and tail of the td list and calculate
+	 * the number of free elements.
+	 */
+	head = le32_to_cpu(ipc_protocol->p_ap_shm->head_array[pipe->pipe_nr]);
+	tail = le32_to_cpu(ipc_protocol->p_ap_shm->tail_array[pipe->pipe_nr]);
+
+	new_head = head + 1;
+	if (new_head >= pipe->nr_of_entries)
+		new_head = 0;
+
+	if (new_head == tail)
+		return false;
+
+	/* Get the td address. */
+	td = &pipe->tdr_start[head];
+
+	/* Allocate the skbuf for the descriptor. */
+	skb = ipc_pcie_alloc_skb(ipc_protocol->pcie, pipe->buf_size, GFP_ATOMIC,
+				 &mapping, DMA_FROM_DEVICE,
+				 IPC_MEM_DL_ETH_OFFSET);
+	if (!skb)
+		return false;
+
+	td->buffer.address = mapping;
+	td->scs = cpu_to_le32(pipe->buf_size) & cpu_to_le32(SIZE_MASK);
+	td->next = 0;
+
+	/* store the new head value. */
+	ipc_protocol->p_ap_shm->head_array[pipe->pipe_nr] =
+		cpu_to_le32(new_head);
+
+	/* Save the reference to the skbuf. */
+	pipe->skbr_start[head] = skb;
+
+	pipe->nr_of_queued_entries++;
+
+	return true;
+}
+
+/* Processes DL TD's */
+struct sk_buff *ipc_protocol_dl_td_process(struct iosm_protocol *ipc_protocol,
+					   struct ipc_pipe *pipe)
+{
+	u32 tail =
+		le32_to_cpu(ipc_protocol->p_ap_shm->tail_array[pipe->pipe_nr]);
+	struct ipc_protocol_td *p_td;
+	struct sk_buff *skb;
+
+	if (!pipe->tdr_start)
+		return NULL;
+
+	/* Copy the reference to the downlink buffer. */
+	p_td = &pipe->tdr_start[pipe->old_tail];
+	skb = pipe->skbr_start[pipe->old_tail];
+
+	/* Reset the ring elements. */
+	pipe->skbr_start[pipe->old_tail] = NULL;
+
+	pipe->nr_of_queued_entries--;
+
+	pipe->old_tail++;
+	if (pipe->old_tail >= pipe->nr_of_entries)
+		pipe->old_tail = 0;
+
+	if (!skb) {
+		dev_err(ipc_protocol->dev, "skb is null");
+		goto ret;
+	} else if (!p_td->buffer.address) {
+		dev_err(ipc_protocol->dev, "td/buffer address is null");
+		ipc_pcie_kfree_skb(ipc_protocol->pcie, skb);
+		skb = NULL;
+		goto ret;
+	}
+
+	if (!IPC_CB(skb)) {
+		dev_err(ipc_protocol->dev, "pipe# %d, tail: %d skb_cb is NULL",
+			pipe->pipe_nr, tail);
+		ipc_pcie_kfree_skb(ipc_protocol->pcie, skb);
+		skb = NULL;
+		goto ret;
+	}
+
+	if (p_td->buffer.address != IPC_CB(skb)->mapping) {
+		dev_err(ipc_protocol->dev, "invalid buf=%p or skb=%p",
+			(void *)p_td->buffer.address, skb->data);
+		ipc_pcie_kfree_skb(ipc_protocol->pcie, skb);
+		skb = NULL;
+		goto ret;
+	} else if ((le32_to_cpu(p_td->scs) & SIZE_MASK) > pipe->buf_size) {
+		dev_err(ipc_protocol->dev, "invalid buffer size %d > %d",
+			le32_to_cpu(p_td->scs) & SIZE_MASK,
+			pipe->buf_size);
+		ipc_pcie_kfree_skb(ipc_protocol->pcie, skb);
+		skb = NULL;
+		goto ret;
+	} else if (le32_to_cpu(p_td->scs) >> COMPLETION_STATUS ==
+		  IPC_MEM_TD_CS_ABORT) {
+		/* Discard aborted buffers. */
+		dev_dbg(ipc_protocol->dev, "discard 'aborted' buffers");
+		ipc_pcie_kfree_skb(ipc_protocol->pcie, skb);
+		skb = NULL;
+		goto ret;
+	}
+
+	/* Set the length field in skbuf. */
+	skb_put(skb, le32_to_cpu(p_td->scs) & SIZE_MASK);
+
+ret:
+	return skb;
+}
+
+void ipc_protocol_get_head_tail_index(struct iosm_protocol *ipc_protocol,
+				      struct ipc_pipe *pipe, u32 *head,
+				      u32 *tail)
+{
+	struct ipc_protocol_ap_shm *ipc_ap_shm = ipc_protocol->p_ap_shm;
+
+	if (head)
+		*head = le32_to_cpu(ipc_ap_shm->head_array[pipe->pipe_nr]);
+
+	if (tail)
+		*tail = le32_to_cpu(ipc_ap_shm->tail_array[pipe->pipe_nr]);
+}
+
+/* Frees the TDs given to CP.  */
+void ipc_protocol_pipe_cleanup(struct iosm_protocol *ipc_protocol,
+			       struct ipc_pipe *pipe)
+{
+	struct sk_buff *skb;
+	u32 head;
+	u32 tail;
+
+	/* Get the start and the end of the buffer list. */
+	head = le32_to_cpu(ipc_protocol->p_ap_shm->head_array[pipe->pipe_nr]);
+	tail = pipe->old_tail;
+
+	/* Reset tail and head to 0. */
+	ipc_protocol->p_ap_shm->tail_array[pipe->pipe_nr] = 0;
+	ipc_protocol->p_ap_shm->head_array[pipe->pipe_nr] = 0;
+
+	/* Free pending uplink and downlink buffers. */
+	if (pipe->skbr_start) {
+		while (head != tail) {
+			/* Get the reference to the skbuf,
+			 * which is on the way and free it.
+			 */
+			skb = pipe->skbr_start[tail];
+			if (skb)
+				ipc_pcie_kfree_skb(ipc_protocol->pcie, skb);
+
+			tail++;
+			if (tail >= pipe->nr_of_entries)
+				tail = 0;
+		}
+
+		kfree(pipe->skbr_start);
+		pipe->skbr_start = NULL;
+	}
+
+	pipe->old_tail = 0;
+
+	/* Free and reset the td and skbuf circular buffers. kfree is save! */
+	if (pipe->tdr_start) {
+		pci_free_consistent(ipc_protocol->pcie->pci,
+				    sizeof(*pipe->tdr_start) *
+					    pipe->nr_of_entries,
+				    pipe->tdr_start, pipe->phy_tdr_start);
+
+		pipe->tdr_start = NULL;
+	}
+}
+
+enum ipc_mem_device_ipc_state ipc_protocol_get_ipc_status(struct iosm_protocol
+							  *ipc_protocol)
+{
+	return (enum ipc_mem_device_ipc_state)
+		le32_to_cpu(ipc_protocol->p_ap_shm->device_info.ipc_status);
+}
+
+enum ipc_mem_exec_stage
+ipc_protocol_get_ap_exec_stage(struct iosm_protocol *ipc_protocol)
+{
+	return le32_to_cpu(ipc_protocol->p_ap_shm->device_info.execution_stage);
+}
+
+int ipc_protocol_msg_prep(struct iosm_imem *ipc_imem,
+			  enum ipc_msg_prep_type msg_type,
+			  union ipc_msg_prep_args *args)
+{
+	struct iosm_protocol *ipc_protocol = ipc_imem->ipc_protocol;
+
+	switch (msg_type) {
+	case IPC_MSG_PREP_SLEEP:
+		return ipc_protocol_msg_prep_sleep(ipc_protocol, args);
+
+	case IPC_MSG_PREP_PIPE_OPEN:
+		return ipc_protocol_msg_prepipe_open(ipc_protocol, args);
+
+	case IPC_MSG_PREP_PIPE_CLOSE:
+		return ipc_protocol_msg_prepipe_close(ipc_protocol, args);
+
+	case IPC_MSG_PREP_FEATURE_SET:
+		return ipc_protocol_msg_prep_feature_set(ipc_protocol, args);
+
+		/* Unsupported messages in protocol */
+	case IPC_MSG_PREP_MAP:
+	case IPC_MSG_PREP_UNMAP:
+	default:
+		dev_err(ipc_protocol->dev,
+			"unsupported message type: %d in protocol", msg_type);
+		return -EINVAL;
+	}
+}
+
+u32
+ipc_protocol_pm_dev_get_sleep_notification(struct iosm_protocol *ipc_protocol)
+{
+	struct ipc_protocol_ap_shm *ipc_ap_shm = ipc_protocol->p_ap_shm;
+
+	return le32_to_cpu(ipc_ap_shm->device_info.device_sleep_notification);
+}