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, 283 insertions, 0 deletions

diff --git a/drivers/net/wwan/iosm/iosm_ipc_protocol.c b/drivers/net/wwan/iosm/iosm_ipc_protocol.c
new file mode 100644
index 000000000000..834d8b146a94
--- /dev/null
+++ b/drivers/net/wwan/iosm/iosm_ipc_protocol.c
@@ -0,0 +1,283 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020-21 Intel Corporation.
+ */
+
+#include "iosm_ipc_imem.h"
+#include "iosm_ipc_protocol.h"
+#include "iosm_ipc_protocol_ops.h"
+#include "iosm_ipc_pm.h"
+#include "iosm_ipc_task_queue.h"
+
+int ipc_protocol_tq_msg_send(struct iosm_protocol *ipc_protocol,
+			     enum ipc_msg_prep_type msg_type,
+			     union ipc_msg_prep_args *prep_args,
+			     struct ipc_rsp *response)
+{
+	int index = ipc_protocol_msg_prep(ipc_protocol->imem, msg_type,
+					  prep_args);
+
+	/* Store reference towards caller specified response in response ring
+	 * and signal CP
+	 */
+	if (index >= 0 && index < IPC_MEM_MSG_ENTRIES) {
+		ipc_protocol->rsp_ring[index] = response;
+		ipc_protocol_msg_hp_update(ipc_protocol->imem);
+	}
+
+	return index;
+}
+
+/* Callback for message send */
+static int ipc_protocol_tq_msg_send_cb(struct iosm_imem *ipc_imem, int arg,
+				       void *msg, size_t size)
+{
+	struct ipc_call_msg_send_args *send_args = msg;
+	struct iosm_protocol *ipc_protocol = ipc_imem->ipc_protocol;
+
+	return ipc_protocol_tq_msg_send(ipc_protocol, send_args->msg_type,
+					send_args->prep_args,
+					send_args->response);
+}
+
+/* Remove reference to a response. This is typically used when a requestor timed
+ * out and is no longer interested in the response.
+ */
+static int ipc_protocol_tq_msg_remove(struct iosm_imem *ipc_imem, int arg,
+				      void *msg, size_t size)
+{
+	struct iosm_protocol *ipc_protocol = ipc_imem->ipc_protocol;
+
+	ipc_protocol->rsp_ring[arg] = NULL;
+	return 0;
+}
+
+int ipc_protocol_msg_send(struct iosm_protocol *ipc_protocol,
+			  enum ipc_msg_prep_type prep,
+			  union ipc_msg_prep_args *prep_args)
+{
+	struct ipc_call_msg_send_args send_args;
+	unsigned int exec_timeout;
+	struct ipc_rsp response;
+	int index;
+
+	exec_timeout = (ipc_protocol_get_ap_exec_stage(ipc_protocol) ==
+					IPC_MEM_EXEC_STAGE_RUN ?
+				IPC_MSG_COMPLETE_RUN_DEFAULT_TIMEOUT :
+				IPC_MSG_COMPLETE_BOOT_DEFAULT_TIMEOUT);
+
+	/* Trap if called from non-preemptible context */
+	might_sleep();
+
+	response.status = IPC_MEM_MSG_CS_INVALID;
+	init_completion(&response.completion);
+
+	send_args.msg_type = prep;
+	send_args.prep_args = prep_args;
+	send_args.response = &response;
+
+	/* Allocate and prepare message to be sent in tasklet context.
+	 * A positive index returned form tasklet_call references the message
+	 * in case it needs to be cancelled when there is a timeout.
+	 */
+	index = ipc_task_queue_send_task(ipc_protocol->imem,
+					 ipc_protocol_tq_msg_send_cb, 0,
+					 &send_args, 0, true);
+
+	if (index < 0) {
+		dev_err(ipc_protocol->dev, "msg %d failed", prep);
+		return index;
+	}
+
+	/* Wait for the device to respond to the message */
+	switch (wait_for_completion_timeout(&response.completion,
+					    msecs_to_jiffies(exec_timeout))) {
+	case 0:
+		/* Timeout, there was no response from the device.
+		 * Remove the reference to the local response completion
+		 * object as we are no longer interested in the response.
+		 */
+		ipc_task_queue_send_task(ipc_protocol->imem,
+					 ipc_protocol_tq_msg_remove, index,
+					 NULL, 0, true);
+		dev_err(ipc_protocol->dev, "msg timeout");
+		ipc_uevent_send(ipc_protocol->pcie->dev, UEVENT_MDM_TIMEOUT);
+		break;
+	default:
+		/* We got a response in time; check completion status: */
+		if (response.status != IPC_MEM_MSG_CS_SUCCESS) {
+			dev_err(ipc_protocol->dev,
+				"msg completion status error %d",
+				response.status);
+			return -EIO;
+		}
+	}
+
+	return 0;
+}
+
+static int ipc_protocol_msg_send_host_sleep(struct iosm_protocol *ipc_protocol,
+					    u32 state)
+{
+	union ipc_msg_prep_args prep_args = {
+		.sleep.target = 0,
+		.sleep.state = state,
+	};
+
+	return ipc_protocol_msg_send(ipc_protocol, IPC_MSG_PREP_SLEEP,
+				     &prep_args);
+}
+
+void ipc_protocol_doorbell_trigger(struct iosm_protocol *ipc_protocol,
+				   u32 identifier)
+{
+	ipc_pm_signal_hpda_doorbell(&ipc_protocol->pm, identifier, true);
+}
+
+bool ipc_protocol_pm_dev_sleep_handle(struct iosm_protocol *ipc_protocol)
+{
+	u32 ipc_status = ipc_protocol_get_ipc_status(ipc_protocol);
+	u32 requested;
+
+	if (ipc_status != IPC_MEM_DEVICE_IPC_RUNNING) {
+		dev_err(ipc_protocol->dev,
+			"irq ignored, CP IPC state is %d, should be RUNNING",
+			ipc_status);
+
+		/* Stop further processing. */
+		return false;
+	}
+
+	/* Get a copy of the requested PM state by the device and the local
+	 * device PM state.
+	 */
+	requested = ipc_protocol_pm_dev_get_sleep_notification(ipc_protocol);
+
+	return ipc_pm_dev_slp_notification(&ipc_protocol->pm, requested);
+}
+
+static int ipc_protocol_tq_wakeup_dev_slp(struct iosm_imem *ipc_imem, int arg,
+					  void *msg, size_t size)
+{
+	struct iosm_pm *ipc_pm = &ipc_imem->ipc_protocol->pm;
+
+	/* Wakeup from device sleep if it is not ACTIVE */
+	ipc_pm_trigger(ipc_pm, IPC_PM_UNIT_HS, true);
+
+	ipc_pm_trigger(ipc_pm, IPC_PM_UNIT_HS, false);
+
+	return 0;
+}
+
+void ipc_protocol_s2idle_sleep(struct iosm_protocol *ipc_protocol, bool sleep)
+{
+	ipc_pm_set_s2idle_sleep(&ipc_protocol->pm, sleep);
+}
+
+bool ipc_protocol_suspend(struct iosm_protocol *ipc_protocol)
+{
+	if (!ipc_pm_prepare_host_sleep(&ipc_protocol->pm))
+		goto err;
+
+	ipc_task_queue_send_task(ipc_protocol->imem,
+				 ipc_protocol_tq_wakeup_dev_slp, 0, NULL, 0,
+				 true);
+
+	if (!ipc_pm_wait_for_device_active(&ipc_protocol->pm)) {
+		ipc_uevent_send(ipc_protocol->pcie->dev, UEVENT_MDM_TIMEOUT);
+		goto err;
+	}
+
+	/* Send the sleep message for sync sys calls. */
+	dev_dbg(ipc_protocol->dev, "send TARGET_HOST, ENTER_SLEEP");
+	if (ipc_protocol_msg_send_host_sleep(ipc_protocol,
+					     IPC_HOST_SLEEP_ENTER_SLEEP)) {
+		/* Sending ENTER_SLEEP message failed, we are still active */
+		ipc_protocol->pm.host_pm_state = IPC_MEM_HOST_PM_ACTIVE;
+		goto err;
+	}
+
+	ipc_protocol->pm.host_pm_state = IPC_MEM_HOST_PM_SLEEP;
+	return true;
+err:
+	return false;
+}
+
+bool ipc_protocol_resume(struct iosm_protocol *ipc_protocol)
+{
+	if (!ipc_pm_prepare_host_active(&ipc_protocol->pm))
+		return false;
+
+	dev_dbg(ipc_protocol->dev, "send TARGET_HOST, EXIT_SLEEP");
+	if (ipc_protocol_msg_send_host_sleep(ipc_protocol,
+					     IPC_HOST_SLEEP_EXIT_SLEEP)) {
+		ipc_protocol->pm.host_pm_state = IPC_MEM_HOST_PM_SLEEP;
+		return false;
+	}
+
+	ipc_protocol->pm.host_pm_state = IPC_MEM_HOST_PM_ACTIVE;
+
+	return true;
+}
+
+struct iosm_protocol *ipc_protocol_init(struct iosm_imem *ipc_imem)
+{
+	struct iosm_protocol *ipc_protocol =
+		kzalloc(sizeof(*ipc_protocol), GFP_KERNEL);
+	struct ipc_protocol_context_info *p_ci;
+	u64 addr;
+
+	if (!ipc_protocol)
+		return NULL;
+
+	ipc_protocol->dev = ipc_imem->dev;
+	ipc_protocol->pcie = ipc_imem->pcie;
+	ipc_protocol->imem = ipc_imem;
+	ipc_protocol->p_ap_shm = NULL;
+	ipc_protocol->phy_ap_shm = 0;
+
+	ipc_protocol->old_msg_tail = 0;
+
+	ipc_protocol->p_ap_shm =
+		pci_alloc_consistent(ipc_protocol->pcie->pci,
+				     sizeof(*ipc_protocol->p_ap_shm),
+				     &ipc_protocol->phy_ap_shm);
+
+	if (!ipc_protocol->p_ap_shm) {
+		dev_err(ipc_protocol->dev, "pci shm alloc error");
+		kfree(ipc_protocol);
+		return NULL;
+	}
+
+	/* Prepare the context info for CP. */
+	addr = ipc_protocol->phy_ap_shm;
+	p_ci = &ipc_protocol->p_ap_shm->ci;
+	p_ci->device_info_addr =
+		addr + offsetof(struct ipc_protocol_ap_shm, device_info);
+	p_ci->head_array =
+		addr + offsetof(struct ipc_protocol_ap_shm, head_array);
+	p_ci->tail_array =
+		addr + offsetof(struct ipc_protocol_ap_shm, tail_array);
+	p_ci->msg_head = addr + offsetof(struct ipc_protocol_ap_shm, msg_head);
+	p_ci->msg_tail = addr + offsetof(struct ipc_protocol_ap_shm, msg_tail);
+	p_ci->msg_ring_addr =
+		addr + offsetof(struct ipc_protocol_ap_shm, msg_ring);
+	p_ci->msg_ring_entries = cpu_to_le16(IPC_MEM_MSG_ENTRIES);
+	p_ci->msg_irq_vector = IPC_MSG_IRQ_VECTOR;
+	p_ci->device_info_irq_vector = IPC_DEVICE_IRQ_VECTOR;
+
+	ipc_mmio_set_contex_info_addr(ipc_imem->mmio, addr);
+
+	ipc_pm_init(ipc_protocol);
+
+	return ipc_protocol;
+}
+
+void ipc_protocol_deinit(struct iosm_protocol *proto)
+{
+	pci_free_consistent(proto->pcie->pci, sizeof(*proto->p_ap_shm),
+			    proto->p_ap_shm, proto->phy_ap_shm);
+
+	ipc_pm_deinit(proto);
+	kfree(proto);
+}