14 files changed, 1306 insertions, 14 deletions
diff --git a/drivers/net/wwan/Kconfig b/drivers/net/wwan/Kconfig
index 17543be14665..609fd4a2c865 100644
--- a/drivers/net/wwan/Kconfig
+++ b/drivers/net/wwan/Kconfig
@@ -16,6 +16,17 @@ config WWAN
 
 if WWAN
 
+config WWAN_DEBUGFS
+	bool "WWAN devices debugfs interface" if EXPERT
+	depends on DEBUG_FS
+	default y
+	help
+	  Enables debugfs infrastructure for the WWAN core and device drivers.
+
+	  If this option is selected, then you can find the debug interface
+	  elements for each WWAN device in a directory that is corresponding to
+	  the device name: debugfs/wwan/wwanX.
+
 config WWAN_HWSIM
 	tristate "Simulated WWAN device"
 	help
@@ -50,6 +61,19 @@ config MHI_WWAN_MBIM
           To compile this driver as a module, choose M here: the module will be
           called mhi_wwan_mbim.
 
+config QCOM_BAM_DMUX
+	tristate "Qualcomm BAM-DMUX WWAN network driver"
+	depends on (DMA_ENGINE && PM && QCOM_SMEM_STATE) || COMPILE_TEST
+	help
+	  The BAM Data Multiplexer provides access to the network data channels
+	  of modems integrated into many older Qualcomm SoCs, e.g. Qualcomm
+	  MSM8916 or MSM8974. The connection can be established via QMI/AT from
+	  userspace with control ports available through the WWAN subsystem
+	  (CONFIG_RPMSG_WWAN_CTRL) or QRTR network sockets (CONFIG_QRTR).
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called qcom_bam_dmux.
+
 config RPMSG_WWAN_CTRL
 	tristate "RPMSG WWAN control driver"
 	depends on RPMSG
@@ -72,6 +96,7 @@ config IOSM
 	tristate "IOSM Driver for Intel M.2 WWAN Device"
 	depends on INTEL_IOMMU
 	select NET_DEVLINK
+	select RELAY if WWAN_DEBUGFS
 	help
 	  This driver enables Intel M.2 WWAN Device communication.
 
diff --git a/drivers/net/wwan/Makefile b/drivers/net/wwan/Makefile
index fe51feedac21..e722650bebea 100644
--- a/drivers/net/wwan/Makefile
+++ b/drivers/net/wwan/Makefile
@@ -10,5 +10,6 @@ obj-$(CONFIG_WWAN_HWSIM) += wwan_hwsim.o
 
 obj-$(CONFIG_MHI_WWAN_CTRL) += mhi_wwan_ctrl.o
 obj-$(CONFIG_MHI_WWAN_MBIM) += mhi_wwan_mbim.o
+obj-$(CONFIG_QCOM_BAM_DMUX) += qcom_bam_dmux.o
 obj-$(CONFIG_RPMSG_WWAN_CTRL) += rpmsg_wwan_ctrl.o
 obj-$(CONFIG_IOSM) += iosm/
diff --git a/drivers/net/wwan/iosm/Makefile b/drivers/net/wwan/iosm/Makefile
index b838034bb120..fa8d6afd18e1 100644
--- a/drivers/net/wwan/iosm/Makefile
+++ b/drivers/net/wwan/iosm/Makefile
@@ -23,4 +23,8 @@ iosm-y = \
 	iosm_ipc_flash.o		\
 	iosm_ipc_coredump.o
 
+iosm-$(CONFIG_WWAN_DEBUGFS) += \
+	iosm_ipc_debugfs.o		\
+	iosm_ipc_trace.o
+
 obj-$(CONFIG_IOSM) := iosm.o
diff --git a/drivers/net/wwan/iosm/iosm_ipc_debugfs.c b/drivers/net/wwan/iosm/iosm_ipc_debugfs.c
new file mode 100644
index 000000000000..f2f57751a7d2
--- /dev/null
+++ b/drivers/net/wwan/iosm/iosm_ipc_debugfs.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020-2021 Intel Corporation.
+ */
+
+#include <linux/debugfs.h>
+#include <linux/wwan.h>
+
+#include "iosm_ipc_imem.h"
+#include "iosm_ipc_trace.h"
+#include "iosm_ipc_debugfs.h"
+
+void ipc_debugfs_init(struct iosm_imem *ipc_imem)
+{
+	struct dentry *debugfs_pdev = wwan_get_debugfs_dir(ipc_imem->dev);
+
+	ipc_imem->debugfs_dir = debugfs_create_dir(KBUILD_MODNAME,
+						   debugfs_pdev);
+
+	ipc_imem->trace = ipc_trace_init(ipc_imem);
+	if (!ipc_imem->trace)
+		dev_warn(ipc_imem->dev, "trace channel init failed");
+}
+
+void ipc_debugfs_deinit(struct iosm_imem *ipc_imem)
+{
+	ipc_trace_deinit(ipc_imem->trace);
+	debugfs_remove_recursive(ipc_imem->debugfs_dir);
+}
diff --git a/drivers/net/wwan/iosm/iosm_ipc_debugfs.h b/drivers/net/wwan/iosm/iosm_ipc_debugfs.h
new file mode 100644
index 000000000000..8a84bfa2c14a
--- /dev/null
+++ b/drivers/net/wwan/iosm/iosm_ipc_debugfs.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0-only
+ *
+ * Copyright (C) 2020-2021 Intel Corporation.
+ */
+
+#ifndef IOSM_IPC_DEBUGFS_H
+#define IOSM_IPC_DEBUGFS_H
+
+#ifdef CONFIG_WWAN_DEBUGFS
+void ipc_debugfs_init(struct iosm_imem *ipc_imem);
+void ipc_debugfs_deinit(struct iosm_imem *ipc_imem);
+#else
+static inline void ipc_debugfs_init(struct iosm_imem *ipc_imem) {}
+static inline void ipc_debugfs_deinit(struct iosm_imem *ipc_imem) {}
+#endif
+
+#endif
diff --git a/drivers/net/wwan/iosm/iosm_ipc_imem.c b/drivers/net/wwan/iosm/iosm_ipc_imem.c
index 12c03dacb5dd..fb4e58beb366 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_imem.c
+++ b/drivers/net/wwan/iosm/iosm_ipc_imem.c
@@ -10,6 +10,8 @@
 #include "iosm_ipc_flash.h"
 #include "iosm_ipc_imem.h"
 #include "iosm_ipc_port.h"
+#include "iosm_ipc_trace.h"
+#include "iosm_ipc_debugfs.h"
 
 /* Check the wwan ips if it is valid with Channel as input. */
 static int ipc_imem_check_wwan_ips(struct ipc_mem_channel *chnl)
@@ -269,9 +271,14 @@ static void ipc_imem_dl_skb_process(struct iosm_imem *ipc_imem,
 	switch (pipe->channel->ctype) {
 	case IPC_CTYPE_CTRL:
 		port_id = pipe->channel->channel_id;
+		ipc_pcie_addr_unmap(ipc_imem->pcie, IPC_CB(skb)->len,
+				    IPC_CB(skb)->mapping,
+				    IPC_CB(skb)->direction);
 		if (port_id == IPC_MEM_CTRL_CHL_ID_7)
 			ipc_imem_sys_devlink_notify_rx(ipc_imem->ipc_devlink,
 						       skb);
+		else if (ipc_is_trace_channel(ipc_imem, port_id))
+			ipc_trace_port_rx(ipc_imem, skb);
 		else
 			wwan_port_rx(ipc_imem->ipc_port[port_id]->iosm_port,
 				     skb);
@@ -555,6 +562,8 @@ static void ipc_imem_run_state_worker(struct work_struct *instance)
 		ctrl_chl_idx++;
 	}
 
+	ipc_debugfs_init(ipc_imem);
+
 	ipc_task_queue_send_task(ipc_imem, ipc_imem_send_mdm_rdy_cb, 0, NULL, 0,
 				 false);
 
@@ -1170,6 +1179,7 @@ void ipc_imem_cleanup(struct iosm_imem *ipc_imem)
 
 	if (test_and_clear_bit(FULLY_FUNCTIONAL, &ipc_imem->flag)) {
 		ipc_mux_deinit(ipc_imem->mux);
+		ipc_debugfs_deinit(ipc_imem);
 		ipc_wwan_deinit(ipc_imem->wwan);
 		ipc_port_deinit(ipc_imem->ipc_port);
 	}
diff --git a/drivers/net/wwan/iosm/iosm_ipc_imem.h b/drivers/net/wwan/iosm/iosm_ipc_imem.h
index 6b8a837faef2..98554e9beb01 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_imem.h
+++ b/drivers/net/wwan/iosm/iosm_ipc_imem.h
@@ -305,6 +305,7 @@ enum ipc_phase {
  * @sio:			IPC SIO data structure pointer
  * @ipc_port:			IPC PORT data structure pointer
  * @pcie:			IPC PCIe
+ * @trace:			IPC trace data structure pointer
  * @dev:			Pointer to device structure
  * @ipc_requested_state:	Expected IPC state on CP.
  * @channels:			Channel list with UL/DL pipe pairs.
@@ -339,6 +340,7 @@ enum ipc_phase {
  * @ev_mux_net_transmit_pending:0 means inform the IPC tasklet to pass
  * @reset_det_n:		Reset detect flag
  * @pcie_wake_n:		Pcie wake flag
+ * @debugfs_dir:		Debug FS directory for driver-specific entries
  */
 struct iosm_imem {
 	struct iosm_mmio *mmio;
@@ -348,6 +350,9 @@ struct iosm_imem {
 	struct iosm_mux *mux;
 	struct iosm_cdev *ipc_port[IPC_MEM_MAX_CHANNELS];
 	struct iosm_pcie *pcie;
+#ifdef CONFIG_WWAN_DEBUGFS
+	struct iosm_trace *trace;
+#endif
 	struct device *dev;
 	enum ipc_mem_device_ipc_state ipc_requested_state;
 	struct ipc_mem_channel channels[IPC_MEM_MAX_CHANNELS];
@@ -376,6 +381,9 @@ struct iosm_imem {
 	   ev_mux_net_transmit_pending:1,
 	   reset_det_n:1,
 	   pcie_wake_n:1;
+#ifdef CONFIG_WWAN_DEBUGFS
+	struct dentry *debugfs_dir;
+#endif
 };
 
 /**
diff --git a/drivers/net/wwan/iosm/iosm_ipc_imem_ops.c b/drivers/net/wwan/iosm/iosm_ipc_imem_ops.c
index 831cdae28e8a..57304a5adf68 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_imem_ops.c
+++ b/drivers/net/wwan/iosm/iosm_ipc_imem_ops.c
@@ -176,11 +176,14 @@ channel_unavailable:
 	return false;
 }
 
-/* Release a sio link to CP. */
-void ipc_imem_sys_cdev_close(struct iosm_cdev *ipc_cdev)
+/**
+ * ipc_imem_sys_port_close - Release a sio link to CP.
+ * @ipc_imem:          Imem instance.
+ * @channel:           Channel instance.
+ */
+void ipc_imem_sys_port_close(struct iosm_imem *ipc_imem,
+			     struct ipc_mem_channel *channel)
 {
-	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;
@@ -638,6 +641,6 @@ int ipc_imem_sys_devlink_read(struct iosm_devlink *devlink, u8 *data,
 	memcpy(data, skb->data, skb->len);
 
 devlink_read_fail:
-	ipc_pcie_kfree_skb(devlink->pcie, skb);
+	dev_kfree_skb(skb);
 	return rc;
 }
diff --git a/drivers/net/wwan/iosm/iosm_ipc_imem_ops.h b/drivers/net/wwan/iosm/iosm_ipc_imem_ops.h
index f0c88ac5643c..f8afb217d9e2 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_imem_ops.h
+++ b/drivers/net/wwan/iosm/iosm_ipc_imem_ops.h
@@ -43,12 +43,8 @@
  */
 struct ipc_mem_channel *ipc_imem_sys_port_open(struct iosm_imem *ipc_imem,
 					       int chl_id, int hp_id);
-
-/**
- * ipc_imem_sys_cdev_close - Release a sio link to CP.
- * @ipc_cdev:		iosm sio instance.
- */
-void ipc_imem_sys_cdev_close(struct iosm_cdev *ipc_cdev);
+void ipc_imem_sys_port_close(struct iosm_imem *ipc_imem,
+			     struct ipc_mem_channel *channel);
 
 /**
  * ipc_imem_sys_cdev_write - Route the uplink buffer to CP.
@@ -145,4 +141,5 @@ int ipc_imem_sys_devlink_read(struct iosm_devlink *ipc_devlink, u8 *data,
  */
 int ipc_imem_sys_devlink_write(struct iosm_devlink *ipc_devlink,
 			       unsigned char *buf, int count);
+
 #endif
diff --git a/drivers/net/wwan/iosm/iosm_ipc_port.c b/drivers/net/wwan/iosm/iosm_ipc_port.c
index beb944847398..b6d81c627277 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_port.c
+++ b/drivers/net/wwan/iosm/iosm_ipc_port.c
@@ -27,7 +27,7 @@ static void ipc_port_ctrl_stop(struct wwan_port *port)
 {
 	struct iosm_cdev *ipc_port = wwan_port_get_drvdata(port);
 
-	ipc_imem_sys_cdev_close(ipc_port);
+	ipc_imem_sys_port_close(ipc_port->ipc_imem, ipc_port->channel);
 }
 
 /* transfer control data to modem */
diff --git a/drivers/net/wwan/iosm/iosm_ipc_trace.c b/drivers/net/wwan/iosm/iosm_ipc_trace.c
new file mode 100644
index 000000000000..eeecfa3d10c5
--- /dev/null
+++ b/drivers/net/wwan/iosm/iosm_ipc_trace.c
@@ -0,0 +1,182 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020-2021 Intel Corporation.
+ */
+
+#include <linux/wwan.h>
+#include "iosm_ipc_trace.h"
+
+/* sub buffer size and number of sub buffer */
+#define IOSM_TRC_SUB_BUFF_SIZE 131072
+#define IOSM_TRC_N_SUB_BUFF 32
+
+#define IOSM_TRC_FILE_PERM 0600
+
+#define IOSM_TRC_DEBUGFS_TRACE "trace"
+#define IOSM_TRC_DEBUGFS_TRACE_CTRL "trace_ctrl"
+
+/**
+ * ipc_trace_port_rx - Receive trace packet from cp and write to relay buffer
+ * @ipc_imem:   Pointer to iosm_imem structure
+ * @skb:        Pointer to struct sk_buff
+ */
+void ipc_trace_port_rx(struct iosm_imem *ipc_imem, struct sk_buff *skb)
+{
+	struct iosm_trace *ipc_trace = ipc_imem->trace;
+
+	if (ipc_trace->ipc_rchan)
+		relay_write(ipc_trace->ipc_rchan, skb->data, skb->len);
+
+	dev_kfree_skb(skb);
+}
+
+/* Creates relay file in debugfs. */
+static struct dentry *
+ipc_trace_create_buf_file_handler(const char *filename,
+				  struct dentry *parent,
+				  umode_t mode,
+				  struct rchan_buf *buf,
+				  int *is_global)
+{
+	*is_global = 1;
+	return debugfs_create_file(filename, mode, parent, buf,
+				   &relay_file_operations);
+}
+
+/* Removes relay file from debugfs. */
+static int ipc_trace_remove_buf_file_handler(struct dentry *dentry)
+{
+	debugfs_remove(dentry);
+	return 0;
+}
+
+static int ipc_trace_subbuf_start_handler(struct rchan_buf *buf, void *subbuf,
+					  void *prev_subbuf,
+					  size_t prev_padding)
+{
+	if (relay_buf_full(buf)) {
+		pr_err_ratelimited("Relay_buf full dropping traces");
+		return 0;
+	}
+
+	return 1;
+}
+
+/* Relay interface callbacks */
+static struct rchan_callbacks relay_callbacks = {
+	.subbuf_start = ipc_trace_subbuf_start_handler,
+	.create_buf_file = ipc_trace_create_buf_file_handler,
+	.remove_buf_file = ipc_trace_remove_buf_file_handler,
+};
+
+/* Copy the trace control mode to user buffer */
+static ssize_t ipc_trace_ctrl_file_read(struct file *filp, char __user *buffer,
+					size_t count, loff_t *ppos)
+{
+	struct iosm_trace *ipc_trace = filp->private_data;
+	char buf[16];
+	int len;
+
+	mutex_lock(&ipc_trace->trc_mutex);
+	len = snprintf(buf, sizeof(buf), "%d\n", ipc_trace->mode);
+	mutex_unlock(&ipc_trace->trc_mutex);
+
+	return simple_read_from_buffer(buffer, count, ppos, buf, len);
+}
+
+/* Open and close the trace channel depending on user input */
+static ssize_t ipc_trace_ctrl_file_write(struct file *filp,
+					 const char __user *buffer,
+					 size_t count, loff_t *ppos)
+{
+	struct iosm_trace *ipc_trace = filp->private_data;
+	unsigned long val;
+	int ret;
+
+	ret = kstrtoul_from_user(buffer, count, 10, &val);
+	if (ret)
+		return ret;
+
+	mutex_lock(&ipc_trace->trc_mutex);
+	if (val == TRACE_ENABLE && ipc_trace->mode != TRACE_ENABLE) {
+		ipc_trace->channel = ipc_imem_sys_port_open(ipc_trace->ipc_imem,
+							    ipc_trace->chl_id,
+							    IPC_HP_CDEV_OPEN);
+		if (!ipc_trace->channel) {
+			ret = -EIO;
+			goto unlock;
+		}
+		ipc_trace->mode = TRACE_ENABLE;
+	} else if (val == TRACE_DISABLE && ipc_trace->mode != TRACE_DISABLE) {
+		ipc_trace->mode = TRACE_DISABLE;
+		/* close trace channel */
+		ipc_imem_sys_port_close(ipc_trace->ipc_imem,
+					ipc_trace->channel);
+		relay_flush(ipc_trace->ipc_rchan);
+	}
+	ret = count;
+unlock:
+	mutex_unlock(&ipc_trace->trc_mutex);
+	return ret;
+}
+
+static const struct file_operations ipc_trace_fops = {
+	.open = simple_open,
+	.write = ipc_trace_ctrl_file_write,
+	.read  = ipc_trace_ctrl_file_read,
+};
+
+/**
+ * ipc_trace_init - Create trace interface & debugfs entries
+ * @ipc_imem:   Pointer to iosm_imem structure
+ *
+ * Returns: Pointer to trace instance on success else NULL
+ */
+struct iosm_trace *ipc_trace_init(struct iosm_imem *ipc_imem)
+{
+	struct ipc_chnl_cfg chnl_cfg = { 0 };
+	struct iosm_trace *ipc_trace;
+
+	ipc_chnl_cfg_get(&chnl_cfg, IPC_MEM_CTRL_CHL_ID_3);
+	ipc_imem_channel_init(ipc_imem, IPC_CTYPE_CTRL, chnl_cfg,
+			      IRQ_MOD_OFF);
+
+	ipc_trace = kzalloc(sizeof(*ipc_trace), GFP_KERNEL);
+	if (!ipc_trace)
+		return NULL;
+
+	ipc_trace->mode = TRACE_DISABLE;
+	ipc_trace->dev = ipc_imem->dev;
+	ipc_trace->ipc_imem = ipc_imem;
+	ipc_trace->chl_id = IPC_MEM_CTRL_CHL_ID_3;
+
+	mutex_init(&ipc_trace->trc_mutex);
+
+	ipc_trace->ctrl_file = debugfs_create_file(IOSM_TRC_DEBUGFS_TRACE_CTRL,
+						   IOSM_TRC_FILE_PERM,
+						   ipc_imem->debugfs_dir,
+						   ipc_trace, &ipc_trace_fops);
+
+	ipc_trace->ipc_rchan = relay_open(IOSM_TRC_DEBUGFS_TRACE,
+					  ipc_imem->debugfs_dir,
+					  IOSM_TRC_SUB_BUFF_SIZE,
+					  IOSM_TRC_N_SUB_BUFF,
+					  &relay_callbacks, NULL);
+
+	return ipc_trace;
+}
+
+/**
+ * ipc_trace_deinit - Closing relayfs, removing debugfs entries
+ * @ipc_trace: Pointer to the iosm_trace data struct
+ */
+void ipc_trace_deinit(struct iosm_trace *ipc_trace)
+{
+	if (!ipc_trace)
+		return;
+
+	debugfs_remove(ipc_trace->ctrl_file);
+	relay_close(ipc_trace->ipc_rchan);
+	mutex_destroy(&ipc_trace->trc_mutex);
+	kfree(ipc_trace);
+}
diff --git a/drivers/net/wwan/iosm/iosm_ipc_trace.h b/drivers/net/wwan/iosm/iosm_ipc_trace.h
new file mode 100644
index 000000000000..5ebe7790585c
--- /dev/null
+++ b/drivers/net/wwan/iosm/iosm_ipc_trace.h
@@ -0,0 +1,74 @@
+/* SPDX-License-Identifier: GPL-2.0-only
+ *
+ * Copyright (C) 2020-2021 Intel Corporation.
+ */
+
+#ifndef IOSM_IPC_TRACE_H
+#define IOSM_IPC_TRACE_H
+
+#include <linux/debugfs.h>
+#include <linux/relay.h>
+
+#include "iosm_ipc_chnl_cfg.h"
+#include "iosm_ipc_imem_ops.h"
+
+/**
+ * enum trace_ctrl_mode - State of trace channel
+ * @TRACE_DISABLE:	mode for disable trace
+ * @TRACE_ENABLE:	mode for enable trace
+ */
+enum trace_ctrl_mode {
+	TRACE_DISABLE = 0,
+	TRACE_ENABLE,
+};
+
+/**
+ * struct iosm_trace - Struct for trace interface
+ * @ipc_rchan:		Pointer to relay channel
+ * @ctrl_file:		Pointer to trace control file
+ * @ipc_imem:		Imem instance
+ * @dev:		Pointer to device struct
+ * @channel:		Channel instance
+ * @chl_id:		Channel Indentifier
+ * @trc_mutex:		Mutex used for read and write mode
+ * @mode:		Mode for enable and disable trace
+ */
+
+struct iosm_trace {
+	struct rchan *ipc_rchan;
+	struct dentry *ctrl_file;
+	struct iosm_imem *ipc_imem;
+	struct device *dev;
+	struct ipc_mem_channel *channel;
+	enum ipc_channel_id chl_id;
+	struct mutex trc_mutex;	/* Mutex used for read and write mode */
+	enum trace_ctrl_mode mode;
+};
+
+#ifdef CONFIG_WWAN_DEBUGFS
+
+static inline bool ipc_is_trace_channel(struct iosm_imem *ipc_mem, u16 chl_id)
+{
+	return ipc_mem->trace && ipc_mem->trace->chl_id == chl_id;
+}
+
+struct iosm_trace *ipc_trace_init(struct iosm_imem *ipc_imem);
+void ipc_trace_deinit(struct iosm_trace *ipc_trace);
+void ipc_trace_port_rx(struct iosm_imem *ipc_imem, struct sk_buff *skb);
+
+#else
+
+static inline bool ipc_is_trace_channel(struct iosm_imem *ipc_mem, u16 chl_id)
+{
+	return false;
+}
+
+static inline void ipc_trace_port_rx(struct iosm_imem *ipc_imem,
+				     struct sk_buff *skb)
+{
+	dev_kfree_skb(skb);
+}
+
+#endif
+
+#endif
diff --git a/drivers/net/wwan/qcom_bam_dmux.c b/drivers/net/wwan/qcom_bam_dmux.c
new file mode 100644
index 000000000000..5dfa2eba6014
--- /dev/null
+++ b/drivers/net/wwan/qcom_bam_dmux.c
@@ -0,0 +1,907 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Qualcomm BAM-DMUX WWAN network driver
+ * Copyright (c) 2020, Stephan Gerhold <stephan@gerhold.net>
+ */
+
+#include <linux/atomic.h>
+#include <linux/bitops.h>
+#include <linux/completion.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/if_arp.h>
+#include <linux/interrupt.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/soc/qcom/smem_state.h>
+#include <linux/spinlock.h>
+#include <linux/wait.h>
+#include <linux/workqueue.h>
+#include <net/pkt_sched.h>
+
+#define BAM_DMUX_BUFFER_SIZE		SZ_2K
+#define BAM_DMUX_HDR_SIZE		sizeof(struct bam_dmux_hdr)
+#define BAM_DMUX_MAX_DATA_SIZE		(BAM_DMUX_BUFFER_SIZE - BAM_DMUX_HDR_SIZE)
+#define BAM_DMUX_NUM_SKB		32
+
+#define BAM_DMUX_HDR_MAGIC		0x33fc
+
+#define BAM_DMUX_AUTOSUSPEND_DELAY	1000
+#define BAM_DMUX_REMOTE_TIMEOUT		msecs_to_jiffies(2000)
+
+enum {
+	BAM_DMUX_CMD_DATA,
+	BAM_DMUX_CMD_OPEN,
+	BAM_DMUX_CMD_CLOSE,
+};
+
+enum {
+	BAM_DMUX_CH_DATA_0,
+	BAM_DMUX_CH_DATA_1,
+	BAM_DMUX_CH_DATA_2,
+	BAM_DMUX_CH_DATA_3,
+	BAM_DMUX_CH_DATA_4,
+	BAM_DMUX_CH_DATA_5,
+	BAM_DMUX_CH_DATA_6,
+	BAM_DMUX_CH_DATA_7,
+	BAM_DMUX_NUM_CH
+};
+
+struct bam_dmux_hdr {
+	u16 magic;
+	u8 signal;
+	u8 cmd;
+	u8 pad;
+	u8 ch;
+	u16 len;
+};
+
+struct bam_dmux_skb_dma {
+	struct bam_dmux *dmux;
+	struct sk_buff *skb;
+	dma_addr_t addr;
+};
+
+struct bam_dmux {
+	struct device *dev;
+
+	int pc_irq;
+	bool pc_state, pc_ack_state;
+	struct qcom_smem_state *pc, *pc_ack;
+	u32 pc_mask, pc_ack_mask;
+	wait_queue_head_t pc_wait;
+	struct completion pc_ack_completion;
+
+	struct dma_chan *rx, *tx;
+	struct bam_dmux_skb_dma rx_skbs[BAM_DMUX_NUM_SKB];
+	struct bam_dmux_skb_dma tx_skbs[BAM_DMUX_NUM_SKB];
+	spinlock_t tx_lock; /* Protect tx_skbs, tx_next_skb */
+	unsigned int tx_next_skb;
+	atomic_long_t tx_deferred_skb;
+	struct work_struct tx_wakeup_work;
+
+	DECLARE_BITMAP(remote_channels, BAM_DMUX_NUM_CH);
+	struct work_struct register_netdev_work;
+	struct net_device *netdevs[BAM_DMUX_NUM_CH];
+};
+
+struct bam_dmux_netdev {
+	struct bam_dmux *dmux;
+	u8 ch;
+};
+
+static void bam_dmux_pc_vote(struct bam_dmux *dmux, bool enable)
+{
+	reinit_completion(&dmux->pc_ack_completion);
+	qcom_smem_state_update_bits(dmux->pc, dmux->pc_mask,
+				    enable ? dmux->pc_mask : 0);
+}
+
+static void bam_dmux_pc_ack(struct bam_dmux *dmux)
+{
+	qcom_smem_state_update_bits(dmux->pc_ack, dmux->pc_ack_mask,
+				    dmux->pc_ack_state ? 0 : dmux->pc_ack_mask);
+	dmux->pc_ack_state = !dmux->pc_ack_state;
+}
+
+static bool bam_dmux_skb_dma_map(struct bam_dmux_skb_dma *skb_dma,
+				 enum dma_data_direction dir)
+{
+	struct device *dev = skb_dma->dmux->dev;
+
+	skb_dma->addr = dma_map_single(dev, skb_dma->skb->data, skb_dma->skb->len, dir);
+	if (dma_mapping_error(dev, skb_dma->addr)) {
+		dev_err(dev, "Failed to DMA map buffer\n");
+		skb_dma->addr = 0;
+		return false;
+	}
+
+	return true;
+}
+
+static void bam_dmux_skb_dma_unmap(struct bam_dmux_skb_dma *skb_dma,
+				   enum dma_data_direction dir)
+{
+	dma_unmap_single(skb_dma->dmux->dev, skb_dma->addr, skb_dma->skb->len, dir);
+	skb_dma->addr = 0;
+}
+
+static void bam_dmux_tx_wake_queues(struct bam_dmux *dmux)
+{
+	int i;
+
+	dev_dbg(dmux->dev, "wake queues\n");
+
+	for (i = 0; i < BAM_DMUX_NUM_CH; ++i) {
+		struct net_device *netdev = dmux->netdevs[i];
+
+		if (netdev && netif_running(netdev))
+			netif_wake_queue(netdev);
+	}
+}
+
+static void bam_dmux_tx_stop_queues(struct bam_dmux *dmux)
+{
+	int i;
+
+	dev_dbg(dmux->dev, "stop queues\n");
+
+	for (i = 0; i < BAM_DMUX_NUM_CH; ++i) {
+		struct net_device *netdev = dmux->netdevs[i];
+
+		if (netdev)
+			netif_stop_queue(netdev);
+	}
+}
+
+static void bam_dmux_tx_done(struct bam_dmux_skb_dma *skb_dma)
+{
+	struct bam_dmux *dmux = skb_dma->dmux;
+	unsigned long flags;
+
+	pm_runtime_mark_last_busy(dmux->dev);
+	pm_runtime_put_autosuspend(dmux->dev);
+
+	if (skb_dma->addr)
+		bam_dmux_skb_dma_unmap(skb_dma, DMA_TO_DEVICE);
+
+	spin_lock_irqsave(&dmux->tx_lock, flags);
+	skb_dma->skb = NULL;
+	if (skb_dma == &dmux->tx_skbs[dmux->tx_next_skb % BAM_DMUX_NUM_SKB])
+		bam_dmux_tx_wake_queues(dmux);
+	spin_unlock_irqrestore(&dmux->tx_lock, flags);
+}
+
+static void bam_dmux_tx_callback(void *data)
+{
+	struct bam_dmux_skb_dma *skb_dma = data;
+	struct sk_buff *skb = skb_dma->skb;
+
+	bam_dmux_tx_done(skb_dma);
+	dev_consume_skb_any(skb);
+}
+
+static bool bam_dmux_skb_dma_submit_tx(struct bam_dmux_skb_dma *skb_dma)
+{
+	struct bam_dmux *dmux = skb_dma->dmux;
+	struct dma_async_tx_descriptor *desc;
+
+	desc = dmaengine_prep_slave_single(dmux->tx, skb_dma->addr,
+					   skb_dma->skb->len, DMA_MEM_TO_DEV,
+					   DMA_PREP_INTERRUPT);
+	if (!desc) {
+		dev_err(dmux->dev, "Failed to prepare TX DMA buffer\n");
+		return false;
+	}
+
+	desc->callback = bam_dmux_tx_callback;
+	desc->callback_param = skb_dma;
+	desc->cookie = dmaengine_submit(desc);
+	return true;
+}
+
+static struct bam_dmux_skb_dma *
+bam_dmux_tx_queue(struct bam_dmux *dmux, struct sk_buff *skb)
+{
+	struct bam_dmux_skb_dma *skb_dma;
+	unsigned long flags;
+
+	spin_lock_irqsave(&dmux->tx_lock, flags);
+
+	skb_dma = &dmux->tx_skbs[dmux->tx_next_skb % BAM_DMUX_NUM_SKB];
+	if (skb_dma->skb) {
+		bam_dmux_tx_stop_queues(dmux);
+		spin_unlock_irqrestore(&dmux->tx_lock, flags);
+		return NULL;
+	}
+	skb_dma->skb = skb;
+
+	dmux->tx_next_skb++;
+	if (dmux->tx_skbs[dmux->tx_next_skb % BAM_DMUX_NUM_SKB].skb)
+		bam_dmux_tx_stop_queues(dmux);
+
+	spin_unlock_irqrestore(&dmux->tx_lock, flags);
+	return skb_dma;
+}
+
+static int bam_dmux_send_cmd(struct bam_dmux_netdev *bndev, u8 cmd)
+{
+	struct bam_dmux *dmux = bndev->dmux;
+	struct bam_dmux_skb_dma *skb_dma;
+	struct bam_dmux_hdr *hdr;
+	struct sk_buff *skb;
+	int ret;
+
+	skb = alloc_skb(sizeof(*hdr), GFP_KERNEL);
+	if (!skb)
+		return -ENOMEM;
+
+	hdr = skb_put_zero(skb, sizeof(*hdr));
+	hdr->magic = BAM_DMUX_HDR_MAGIC;
+	hdr->cmd = cmd;
+	hdr->ch = bndev->ch;
+
+	skb_dma = bam_dmux_tx_queue(dmux, skb);
+	if (!skb_dma) {
+		ret = -EAGAIN;
+		goto free_skb;
+	}
+
+	ret = pm_runtime_get_sync(dmux->dev);
+	if (ret < 0)
+		goto tx_fail;
+
+	if (!bam_dmux_skb_dma_map(skb_dma, DMA_TO_DEVICE)) {
+		ret = -ENOMEM;
+		goto tx_fail;
+	}
+
+	if (!bam_dmux_skb_dma_submit_tx(skb_dma)) {
+		ret = -EIO;
+		goto tx_fail;
+	}
+
+	dma_async_issue_pending(dmux->tx);
+	return 0;
+
+tx_fail:
+	bam_dmux_tx_done(skb_dma);
+free_skb:
+	dev_kfree_skb(skb);
+	return ret;
+}
+
+static int bam_dmux_netdev_open(struct net_device *netdev)
+{
+	struct bam_dmux_netdev *bndev = netdev_priv(netdev);
+	int ret;
+
+	ret = bam_dmux_send_cmd(bndev, BAM_DMUX_CMD_OPEN);
+	if (ret)
+		return ret;
+
+	netif_start_queue(netdev);
+	return 0;
+}
+
+static int bam_dmux_netdev_stop(struct net_device *netdev)
+{
+	struct bam_dmux_netdev *bndev = netdev_priv(netdev);
+
+	netif_stop_queue(netdev);
+	bam_dmux_send_cmd(bndev, BAM_DMUX_CMD_CLOSE);
+	return 0;
+}
+
+static unsigned int needed_room(unsigned int avail, unsigned int needed)
+{
+	if (avail >= needed)
+		return 0;
+	return needed - avail;
+}
+
+static int bam_dmux_tx_prepare_skb(struct bam_dmux_netdev *bndev,
+				   struct sk_buff *skb)
+{
+	unsigned int head = needed_room(skb_headroom(skb), BAM_DMUX_HDR_SIZE);
+	unsigned int pad = sizeof(u32) - skb->len % sizeof(u32);
+	unsigned int tail = needed_room(skb_tailroom(skb), pad);
+	struct bam_dmux_hdr *hdr;
+	int ret;
+
+	if (head || tail || skb_cloned(skb)) {
+		ret = pskb_expand_head(skb, head, tail, GFP_ATOMIC);
+		if (ret)
+			return ret;
+	}
+
+	hdr = skb_push(skb, sizeof(*hdr));
+	hdr->magic = BAM_DMUX_HDR_MAGIC;
+	hdr->signal = 0;
+	hdr->cmd = BAM_DMUX_CMD_DATA;
+	hdr->pad = pad;
+	hdr->ch = bndev->ch;
+	hdr->len = skb->len - sizeof(*hdr);
+	if (pad)
+		skb_put_zero(skb, pad);
+
+	return 0;
+}
+
+static netdev_tx_t bam_dmux_netdev_start_xmit(struct sk_buff *skb,
+					      struct net_device *netdev)
+{
+	struct bam_dmux_netdev *bndev = netdev_priv(netdev);
+	struct bam_dmux *dmux = bndev->dmux;
+	struct bam_dmux_skb_dma *skb_dma;
+	int active, ret;
+
+	skb_dma = bam_dmux_tx_queue(dmux, skb);
+	if (!skb_dma)
+		return NETDEV_TX_BUSY;
+
+	active = pm_runtime_get(dmux->dev);
+	if (active < 0 && active != -EINPROGRESS)
+		goto drop;
+
+	ret = bam_dmux_tx_prepare_skb(bndev, skb);
+	if (ret)
+		goto drop;
+
+	if (!bam_dmux_skb_dma_map(skb_dma, DMA_TO_DEVICE))
+		goto drop;
+
+	if (active <= 0) {
+		/* Cannot sleep here so mark skb for wakeup handler and return */
+		if (!atomic_long_fetch_or(BIT(skb_dma - dmux->tx_skbs),
+					  &dmux->tx_deferred_skb))
+			queue_pm_work(&dmux->tx_wakeup_work);
+		return NETDEV_TX_OK;
+	}
+
+	if (!bam_dmux_skb_dma_submit_tx(skb_dma))
+		goto drop;
+
+	dma_async_issue_pending(dmux->tx);
+	return NETDEV_TX_OK;
+
+drop:
+	bam_dmux_tx_done(skb_dma);
+	dev_kfree_skb_any(skb);
+	return NETDEV_TX_OK;
+}
+
+static void bam_dmux_tx_wakeup_work(struct work_struct *work)
+{
+	struct bam_dmux *dmux = container_of(work, struct bam_dmux, tx_wakeup_work);
+	unsigned long pending;
+	int ret, i;
+
+	ret = pm_runtime_resume_and_get(dmux->dev);
+	if (ret < 0) {
+		dev_err(dmux->dev, "Failed to resume: %d\n", ret);
+		return;
+	}
+
+	pending = atomic_long_xchg(&dmux->tx_deferred_skb, 0);
+	if (!pending)
+		goto out;
+
+	dev_dbg(dmux->dev, "pending skbs after wakeup: %#lx\n", pending);
+	for_each_set_bit(i, &pending, BAM_DMUX_NUM_SKB) {
+		bam_dmux_skb_dma_submit_tx(&dmux->tx_skbs[i]);
+	}
+	dma_async_issue_pending(dmux->tx);
+
+out:
+	pm_runtime_mark_last_busy(dmux->dev);
+	pm_runtime_put_autosuspend(dmux->dev);
+}
+
+static const struct net_device_ops bam_dmux_ops = {
+	.ndo_open	= bam_dmux_netdev_open,
+	.ndo_stop	= bam_dmux_netdev_stop,
+	.ndo_start_xmit	= bam_dmux_netdev_start_xmit,
+};
+
+static const struct device_type wwan_type = {
+	.name = "wwan",
+};
+
+static void bam_dmux_netdev_setup(struct net_device *dev)
+{
+	dev->netdev_ops = &bam_dmux_ops;
+
+	dev->type = ARPHRD_RAWIP;
+	SET_NETDEV_DEVTYPE(dev, &wwan_type);
+	dev->flags = IFF_POINTOPOINT | IFF_NOARP;
+
+	dev->mtu = ETH_DATA_LEN;
+	dev->max_mtu = BAM_DMUX_MAX_DATA_SIZE;
+	dev->needed_headroom = sizeof(struct bam_dmux_hdr);
+	dev->needed_tailroom = sizeof(u32); /* word-aligned */
+	dev->tx_queue_len = DEFAULT_TX_QUEUE_LEN;
+
+	/* This perm addr will be used as interface identifier by IPv6 */
+	dev->addr_assign_type = NET_ADDR_RANDOM;
+	eth_random_addr(dev->perm_addr);
+}
+
+static void bam_dmux_register_netdev_work(struct work_struct *work)
+{
+	struct bam_dmux *dmux = container_of(work, struct bam_dmux, register_netdev_work);
+	struct bam_dmux_netdev *bndev;
+	struct net_device *netdev;
+	int ch, ret;
+
+	for_each_set_bit(ch, dmux->remote_channels, BAM_DMUX_NUM_CH) {
+		if (dmux->netdevs[ch])
+			continue;
+
+		netdev = alloc_netdev(sizeof(*bndev), "wwan%d", NET_NAME_ENUM,
+				      bam_dmux_netdev_setup);
+		if (!netdev)
+			return;
+
+		SET_NETDEV_DEV(netdev, dmux->dev);
+		netdev->dev_port = ch;
+
+		bndev = netdev_priv(netdev);
+		bndev->dmux = dmux;
+		bndev->ch = ch;
+
+		ret = register_netdev(netdev);
+		if (ret) {
+			dev_err(dmux->dev, "Failed to register netdev for channel %u: %d\n",
+				ch, ret);
+			free_netdev(netdev);
+			return;
+		}
+
+		dmux->netdevs[ch] = netdev;
+	}
+}
+
+static void bam_dmux_rx_callback(void *data);
+
+static bool bam_dmux_skb_dma_submit_rx(struct bam_dmux_skb_dma *skb_dma)
+{
+	struct bam_dmux *dmux = skb_dma->dmux;
+	struct dma_async_tx_descriptor *desc;
+
+	desc = dmaengine_prep_slave_single(dmux->rx, skb_dma->addr,
+					   skb_dma->skb->len, DMA_DEV_TO_MEM,
+					   DMA_PREP_INTERRUPT);
+	if (!desc) {
+		dev_err(dmux->dev, "Failed to prepare RX DMA buffer\n");
+		return false;
+	}
+
+	desc->callback = bam_dmux_rx_callback;
+	desc->callback_param = skb_dma;
+	desc->cookie = dmaengine_submit(desc);
+	return true;
+}
+
+static bool bam_dmux_skb_dma_queue_rx(struct bam_dmux_skb_dma *skb_dma, gfp_t gfp)
+{
+	if (!skb_dma->skb) {
+		skb_dma->skb = __netdev_alloc_skb(NULL, BAM_DMUX_BUFFER_SIZE, gfp);
+		if (!skb_dma->skb)
+			return false;
+		skb_put(skb_dma->skb, BAM_DMUX_BUFFER_SIZE);
+	}
+
+	return bam_dmux_skb_dma_map(skb_dma, DMA_FROM_DEVICE) &&
+	       bam_dmux_skb_dma_submit_rx(skb_dma);
+}
+
+static void bam_dmux_cmd_data(struct bam_dmux_skb_dma *skb_dma)
+{
+	struct bam_dmux *dmux = skb_dma->dmux;
+	struct sk_buff *skb = skb_dma->skb;
+	struct bam_dmux_hdr *hdr = (struct bam_dmux_hdr *)skb->data;
+	struct net_device *netdev = dmux->netdevs[hdr->ch];
+
+	if (!netdev || !netif_running(netdev)) {
+		dev_warn(dmux->dev, "Data for inactive channel %u\n", hdr->ch);
+		return;
+	}
+
+	if (hdr->len > BAM_DMUX_MAX_DATA_SIZE) {
+		dev_err(dmux->dev, "Data larger than buffer? (%u > %u)\n",
+			hdr->len, (u16)BAM_DMUX_MAX_DATA_SIZE);
+		return;
+	}
+
+	skb_dma->skb = NULL; /* Hand over to network stack */
+
+	skb_pull(skb, sizeof(*hdr));
+	skb_trim(skb, hdr->len);
+	skb->dev = netdev;
+
+	/* Only Raw-IP/QMAP is supported by this driver */
+	switch (skb->data[0] & 0xf0) {
+	case 0x40:
+		skb->protocol = htons(ETH_P_IP);
+		break;
+	case 0x60:
+		skb->protocol = htons(ETH_P_IPV6);
+		break;
+	default:
+		skb->protocol = htons(ETH_P_MAP);
+		break;
+	}
+
+	netif_receive_skb(skb);
+}
+
+static void bam_dmux_cmd_open(struct bam_dmux *dmux, struct bam_dmux_hdr *hdr)
+{
+	struct net_device *netdev = dmux->netdevs[hdr->ch];
+
+	dev_dbg(dmux->dev, "open channel: %u\n", hdr->ch);
+
+	if (__test_and_set_bit(hdr->ch, dmux->remote_channels)) {
+		dev_warn(dmux->dev, "Channel already open: %u\n", hdr->ch);
+		return;
+	}
+
+	if (netdev) {
+		netif_device_attach(netdev);
+	} else {
+		/* Cannot sleep here, schedule work to register the netdev */
+		schedule_work(&dmux->register_netdev_work);
+	}
+}
+
+static void bam_dmux_cmd_close(struct bam_dmux *dmux, struct bam_dmux_hdr *hdr)
+{
+	struct net_device *netdev = dmux->netdevs[hdr->ch];
+
+	dev_dbg(dmux->dev, "close channel: %u\n", hdr->ch);
+
+	if (!__test_and_clear_bit(hdr->ch, dmux->remote_channels)) {
+		dev_err(dmux->dev, "Channel not open: %u\n", hdr->ch);
+		return;
+	}
+
+	if (netdev)
+		netif_device_detach(netdev);
+}
+
+static void bam_dmux_rx_callback(void *data)
+{
+	struct bam_dmux_skb_dma *skb_dma = data;
+	struct bam_dmux *dmux = skb_dma->dmux;
+	struct sk_buff *skb = skb_dma->skb;
+	struct bam_dmux_hdr *hdr = (struct bam_dmux_hdr *)skb->data;
+
+	bam_dmux_skb_dma_unmap(skb_dma, DMA_FROM_DEVICE);
+
+	if (hdr->magic != BAM_DMUX_HDR_MAGIC) {
+		dev_err(dmux->dev, "Invalid magic in header: %#x\n", hdr->magic);
+		goto out;
+	}
+
+	if (hdr->ch >= BAM_DMUX_NUM_CH) {
+		dev_dbg(dmux->dev, "Unsupported channel: %u\n", hdr->ch);
+		goto out;
+	}
+
+	switch (hdr->cmd) {
+	case BAM_DMUX_CMD_DATA:
+		bam_dmux_cmd_data(skb_dma);
+		break;
+	case BAM_DMUX_CMD_OPEN:
+		bam_dmux_cmd_open(dmux, hdr);
+		break;
+	case BAM_DMUX_CMD_CLOSE:
+		bam_dmux_cmd_close(dmux, hdr);
+		break;
+	default:
+		dev_err(dmux->dev, "Unsupported command %u on channel %u\n",
+			hdr->cmd, hdr->ch);
+		break;
+	}
+
+out:
+	if (bam_dmux_skb_dma_queue_rx(skb_dma, GFP_ATOMIC))
+		dma_async_issue_pending(dmux->rx);
+}
+
+static bool bam_dmux_power_on(struct bam_dmux *dmux)
+{
+	struct device *dev = dmux->dev;
+	struct dma_slave_config dma_rx_conf = {
+		.direction = DMA_DEV_TO_MEM,
+		.src_maxburst = BAM_DMUX_BUFFER_SIZE,
+	};
+	int i;
+
+	dmux->rx = dma_request_chan(dev, "rx");
+	if (IS_ERR(dmux->rx)) {
+		dev_err(dev, "Failed to request RX DMA channel: %pe\n", dmux->rx);
+		dmux->rx = NULL;
+		return false;
+	}
+	dmaengine_slave_config(dmux->rx, &dma_rx_conf);
+
+	for (i = 0; i < BAM_DMUX_NUM_SKB; i++) {
+		if (!bam_dmux_skb_dma_queue_rx(&dmux->rx_skbs[i], GFP_KERNEL))
+			return false;
+	}
+	dma_async_issue_pending(dmux->rx);
+
+	return true;
+}
+
+static void bam_dmux_free_skbs(struct bam_dmux_skb_dma skbs[],
+			       enum dma_data_direction dir)
+{
+	int i;
+
+	for (i = 0; i < BAM_DMUX_NUM_SKB; i++) {
+		struct bam_dmux_skb_dma *skb_dma = &skbs[i];
+
+		if (skb_dma->addr)
+			bam_dmux_skb_dma_unmap(skb_dma, dir);
+		if (skb_dma->skb) {
+			dev_kfree_skb(skb_dma->skb);
+			skb_dma->skb = NULL;
+		}
+	}
+}
+
+static void bam_dmux_power_off(struct bam_dmux *dmux)
+{
+	if (dmux->tx) {
+		dmaengine_terminate_sync(dmux->tx);
+		dma_release_channel(dmux->tx);
+		dmux->tx = NULL;
+	}
+
+	if (dmux->rx) {
+		dmaengine_terminate_sync(dmux->rx);
+		dma_release_channel(dmux->rx);
+		dmux->rx = NULL;
+	}
+
+	bam_dmux_free_skbs(dmux->rx_skbs, DMA_FROM_DEVICE);
+}
+
+static irqreturn_t bam_dmux_pc_irq(int irq, void *data)
+{
+	struct bam_dmux *dmux = data;
+	bool new_state = !dmux->pc_state;
+
+	dev_dbg(dmux->dev, "pc: %u\n", new_state);
+
+	if (new_state) {
+		if (bam_dmux_power_on(dmux))
+			bam_dmux_pc_ack(dmux);
+		else
+			bam_dmux_power_off(dmux);
+	} else {
+		bam_dmux_power_off(dmux);
+		bam_dmux_pc_ack(dmux);
+	}
+
+	dmux->pc_state = new_state;
+	wake_up_all(&dmux->pc_wait);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t bam_dmux_pc_ack_irq(int irq, void *data)
+{
+	struct bam_dmux *dmux = data;
+
+	dev_dbg(dmux->dev, "pc ack\n");
+	complete_all(&dmux->pc_ack_completion);
+
+	return IRQ_HANDLED;
+}
+
+static int bam_dmux_runtime_suspend(struct device *dev)
+{
+	struct bam_dmux *dmux = dev_get_drvdata(dev);
+
+	dev_dbg(dev, "runtime suspend\n");
+	bam_dmux_pc_vote(dmux, false);
+
+	return 0;
+}
+
+static int __maybe_unused bam_dmux_runtime_resume(struct device *dev)
+{
+	struct bam_dmux *dmux = dev_get_drvdata(dev);
+
+	dev_dbg(dev, "runtime resume\n");
+
+	/* Wait until previous power down was acked */
+	if (!wait_for_completion_timeout(&dmux->pc_ack_completion,
+					 BAM_DMUX_REMOTE_TIMEOUT))
+		return -ETIMEDOUT;
+
+	/* Vote for power state */
+	bam_dmux_pc_vote(dmux, true);
+
+	/* Wait for ack */
+	if (!wait_for_completion_timeout(&dmux->pc_ack_completion,
+					 BAM_DMUX_REMOTE_TIMEOUT)) {
+		bam_dmux_pc_vote(dmux, false);
+		return -ETIMEDOUT;
+	}
+
+	/* Wait until we're up */
+	if (!wait_event_timeout(dmux->pc_wait, dmux->pc_state,
+				BAM_DMUX_REMOTE_TIMEOUT)) {
+		bam_dmux_pc_vote(dmux, false);
+		return -ETIMEDOUT;
+	}
+
+	/* Ensure that we actually initialized successfully */
+	if (!dmux->rx) {
+		bam_dmux_pc_vote(dmux, false);
+		return -ENXIO;
+	}
+
+	/* Request TX channel if necessary */
+	if (dmux->tx)
+		return 0;
+
+	dmux->tx = dma_request_chan(dev, "tx");
+	if (IS_ERR(dmux->rx)) {
+		dev_err(dev, "Failed to request TX DMA channel: %pe\n", dmux->tx);
+		dmux->tx = NULL;
+		bam_dmux_runtime_suspend(dev);
+		return -ENXIO;
+	}
+
+	return 0;
+}
+
+static int bam_dmux_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct bam_dmux *dmux;
+	int ret, pc_ack_irq, i;
+	unsigned int bit;
+
+	dmux = devm_kzalloc(dev, sizeof(*dmux), GFP_KERNEL);
+	if (!dmux)
+		return -ENOMEM;
+
+	dmux->dev = dev;
+	platform_set_drvdata(pdev, dmux);
+
+	dmux->pc_irq = platform_get_irq_byname(pdev, "pc");
+	if (dmux->pc_irq < 0)
+		return dmux->pc_irq;
+
+	pc_ack_irq = platform_get_irq_byname(pdev, "pc-ack");
+	if (pc_ack_irq < 0)
+		return pc_ack_irq;
+
+	dmux->pc = devm_qcom_smem_state_get(dev, "pc", &bit);
+	if (IS_ERR(dmux->pc))
+		return dev_err_probe(dev, PTR_ERR(dmux->pc),
+				     "Failed to get pc state\n");
+	dmux->pc_mask = BIT(bit);
+
+	dmux->pc_ack = devm_qcom_smem_state_get(dev, "pc-ack", &bit);
+	if (IS_ERR(dmux->pc_ack))
+		return dev_err_probe(dev, PTR_ERR(dmux->pc_ack),
+				     "Failed to get pc-ack state\n");
+	dmux->pc_ack_mask = BIT(bit);
+
+	init_waitqueue_head(&dmux->pc_wait);
+	init_completion(&dmux->pc_ack_completion);
+	complete_all(&dmux->pc_ack_completion);
+
+	spin_lock_init(&dmux->tx_lock);
+	INIT_WORK(&dmux->tx_wakeup_work, bam_dmux_tx_wakeup_work);
+	INIT_WORK(&dmux->register_netdev_work, bam_dmux_register_netdev_work);
+
+	for (i = 0; i < BAM_DMUX_NUM_SKB; i++) {
+		dmux->rx_skbs[i].dmux = dmux;
+		dmux->tx_skbs[i].dmux = dmux;
+	}
+
+	/* Runtime PM manages our own power vote.
+	 * Note that the RX path may be active even if we are runtime suspended,
+	 * since it is controlled by the remote side.
+	 */
+	pm_runtime_set_autosuspend_delay(dev, BAM_DMUX_AUTOSUSPEND_DELAY);
+	pm_runtime_use_autosuspend(dev);
+	pm_runtime_enable(dev);
+
+	ret = devm_request_threaded_irq(dev, pc_ack_irq, NULL, bam_dmux_pc_ack_irq,
+					IRQF_ONESHOT, NULL, dmux);
+	if (ret)
+		return ret;
+
+	ret = devm_request_threaded_irq(dev, dmux->pc_irq, NULL, bam_dmux_pc_irq,
+					IRQF_ONESHOT, NULL, dmux);
+	if (ret)
+		return ret;
+
+	ret = irq_get_irqchip_state(dmux->pc_irq, IRQCHIP_STATE_LINE_LEVEL,
+				    &dmux->pc_state);
+	if (ret)
+		return ret;
+
+	/* Check if remote finished initialization before us */
+	if (dmux->pc_state) {
+		if (bam_dmux_power_on(dmux))
+			bam_dmux_pc_ack(dmux);
+		else
+			bam_dmux_power_off(dmux);
+	}
+
+	return 0;
+}
+
+static int bam_dmux_remove(struct platform_device *pdev)
+{
+	struct bam_dmux *dmux = platform_get_drvdata(pdev);
+	struct device *dev = dmux->dev;
+	LIST_HEAD(list);
+	int i;
+
+	/* Unregister network interfaces */
+	cancel_work_sync(&dmux->register_netdev_work);
+	rtnl_lock();
+	for (i = 0; i < BAM_DMUX_NUM_CH; ++i)
+		if (dmux->netdevs[i])
+			unregister_netdevice_queue(dmux->netdevs[i], &list);
+	unregister_netdevice_many(&list);
+	rtnl_unlock();
+	cancel_work_sync(&dmux->tx_wakeup_work);
+
+	/* Drop our own power vote */
+	pm_runtime_disable(dev);
+	pm_runtime_dont_use_autosuspend(dev);
+	bam_dmux_runtime_suspend(dev);
+	pm_runtime_set_suspended(dev);
+
+	/* Try to wait for remote side to drop power vote */
+	if (!wait_event_timeout(dmux->pc_wait, !dmux->rx, BAM_DMUX_REMOTE_TIMEOUT))
+		dev_err(dev, "Timed out waiting for remote side to suspend\n");
+
+	/* Make sure everything is cleaned up before we return */
+	disable_irq(dmux->pc_irq);
+	bam_dmux_power_off(dmux);
+	bam_dmux_free_skbs(dmux->tx_skbs, DMA_TO_DEVICE);
+
+	return 0;
+}
+
+static const struct dev_pm_ops bam_dmux_pm_ops = {
+	SET_RUNTIME_PM_OPS(bam_dmux_runtime_suspend, bam_dmux_runtime_resume, NULL)
+};
+
+static const struct of_device_id bam_dmux_of_match[] = {
+	{ .compatible = "qcom,bam-dmux" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, bam_dmux_of_match);
+
+static struct platform_driver bam_dmux_driver = {
+	.probe = bam_dmux_probe,
+	.remove = bam_dmux_remove,
+	.driver = {
+		.name = "bam-dmux",
+		.pm = &bam_dmux_pm_ops,
+		.of_match_table = bam_dmux_of_match,
+	},
+};
+module_platform_driver(bam_dmux_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Qualcomm BAM-DMUX WWAN Network Driver");
+MODULE_AUTHOR("Stephan Gerhold <stephan@gerhold.net>");
diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
index d293ab688044..1508dc2a497b 100644
--- a/drivers/net/wwan/wwan_core.c
+++ b/drivers/net/wwan/wwan_core.c
@@ -3,6 +3,7 @@
 
 #include <linux/err.h>
 #include <linux/errno.h>
+#include <linux/debugfs.h>
 #include <linux/fs.h>
 #include <linux/init.h>
 #include <linux/idr.h>
@@ -25,6 +26,7 @@ static DEFINE_IDA(minors); /* minors for WWAN port chardevs */
 static DEFINE_IDA(wwan_dev_ids); /* for unique WWAN device IDs */
 static struct class *wwan_class;
 static int wwan_major;
+static struct dentry *wwan_debugfs_dir;
 
 #define to_wwan_dev(d) container_of(d, struct wwan_device, dev)
 #define to_wwan_port(d) container_of(d, struct wwan_port, dev)
@@ -40,6 +42,7 @@ static int wwan_major;
  * @port_id: Current available port ID to pick.
  * @ops: wwan device ops
  * @ops_ctxt: context to pass to ops
+ * @debugfs_dir:  WWAN device debugfs dir
  */
 struct wwan_device {
 	unsigned int id;
@@ -47,6 +50,9 @@ struct wwan_device {
 	atomic_t port_id;
 	const struct wwan_ops *ops;
 	void *ops_ctxt;
+#ifdef CONFIG_WWAN_DEBUGFS
+	struct dentry *debugfs_dir;
+#endif
 };
 
 /**
@@ -142,6 +148,20 @@ static struct wwan_device *wwan_dev_get_by_name(const char *name)
 	return to_wwan_dev(dev);
 }
 
+#ifdef CONFIG_WWAN_DEBUGFS
+struct dentry *wwan_get_debugfs_dir(struct device *parent)
+{
+	struct wwan_device *wwandev;
+
+	wwandev = wwan_dev_get_by_parent(parent);
+	if (IS_ERR(wwandev))
+		return ERR_CAST(wwandev);
+
+	return wwandev->debugfs_dir;
+}
+EXPORT_SYMBOL_GPL(wwan_get_debugfs_dir);
+#endif
+
 /* This function allocates and registers a new WWAN device OR if a WWAN device
  * already exist for the given parent, it gets a reference and return it.
  * This function is not exported (for now), it is called indirectly via
@@ -189,6 +209,12 @@ static struct wwan_device *wwan_create_dev(struct device *parent)
 		goto done_unlock;
 	}
 
+#ifdef CONFIG_WWAN_DEBUGFS
+	wwandev->debugfs_dir =
+			debugfs_create_dir(kobject_name(&wwandev->dev.kobj),
+					   wwan_debugfs_dir);
+#endif
+
 done_unlock:
 	mutex_unlock(&wwan_register_lock);
 
@@ -218,10 +244,14 @@ static void wwan_remove_dev(struct wwan_device *wwandev)
 	else
 		ret = device_for_each_child(&wwandev->dev, NULL, is_wwan_child);
 
-	if (!ret)
+	if (!ret) {
+#ifdef CONFIG_WWAN_DEBUGFS
+		debugfs_remove_recursive(wwandev->debugfs_dir);
+#endif
 		device_unregister(&wwandev->dev);
-	else
+	} else {
 		put_device(&wwandev->dev);
+	}
 
 	mutex_unlock(&wwan_register_lock);
 }
@@ -1117,6 +1147,10 @@ static int __init wwan_init(void)
 		goto destroy;
 	}
 
+#ifdef CONFIG_WWAN_DEBUGFS
+	wwan_debugfs_dir = debugfs_create_dir("wwan", NULL);
+#endif
+
 	return 0;
 
 destroy:
@@ -1128,6 +1162,7 @@ unregister:
 
 static void __exit wwan_exit(void)
 {
+	debugfs_remove_recursive(wwan_debugfs_dir);
 	__unregister_chrdev(wwan_major, 0, WWAN_MAX_MINORS, "wwan_port");
 	rtnl_link_unregister(&wwan_rtnl_link_ops);
 	class_destroy(wwan_class);