net: wwan: t7xx: Add port for modem logging

The Modem Logging (MDL) port provides an interface to collect modem
logs for debugging purposes. MDL is supported by the relay interface,
and the mtk_t7xx port infrastructure. MDL allows user-space apps to
control logging via mbim command and to collect logs via the relay
interface, while port infrastructure facilitates communication between
the driver and the modem.

Signed-off-by: Moises Veleta <moises.veleta@linux.intel.com>
Signed-off-by: M Chetan Kumar <m.chetan.kumar@linux.intel.com>
Signed-off-by: Devegowda Chandrashekar <chandrashekar.devegowda@intel.com>
Acked-by: Ricardo Martinez <ricardo.martinez@linux.intel.com>
Reviewed-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wwan/Kconfig

@@ -108,6 +108,7 @@ config IOSM
 config MTK_T7XX
 	tristate "MediaTek PCIe 5G WWAN modem T7xx device"
 	depends on PCI
+	select RELAY if WWAN_DEBUGFS
 	help
 	  Enables MediaTek PCIe based 5G WWAN modem (T7xx series) device.
 	  Adapts WWAN framework and provides network interface like wwan0

drivers/net/wwan/t7xx/Makefile

@@ -18,3 +18,6 @@ mtk_t7xx-y:=	t7xx_pci.o \
 		t7xx_hif_dpmaif_rx.o  \
 		t7xx_dpmaif.o \
 		t7xx_netdev.o
+
+mtk_t7xx-$(CONFIG_WWAN_DEBUGFS) += \
+		t7xx_port_trace.o \

drivers/net/wwan/t7xx/t7xx_hif_cldma.c

@@ -1018,6 +1018,8 @@ static int t7xx_cldma_late_init(struct cldma_ctrl *md_ctrl)
 			dev_err(md_ctrl->dev, "control TX ring init fail\n");
 			goto err_free_tx_ring;
 		}
+
+		md_ctrl->tx_ring[i].pkt_size = CLDMA_MTU;
 	}
 
 	for (j = 0; j < CLDMA_RXQ_NUM; j++) {

drivers/net/wwan/t7xx/t7xx_pci.h

@@ -78,6 +78,9 @@ struct t7xx_pci_dev {
 	spinlock_t		md_pm_lock;		/* Protects PCI resource lock */
 	unsigned int		sleep_disable_count;
 	struct completion	sleep_lock_acquire;
+#ifdef CONFIG_WWAN_DEBUGFS
+	struct dentry		*debugfs_dir;
+#endif
 };
 
 enum t7xx_pm_id {

drivers/net/wwan/t7xx/t7xx_port.h

@@ -125,6 +125,9 @@ struct t7xx_port {
 		struct {
 			struct wwan_port		*wwan_port;
 		} wwan;
+		struct {
+			struct rchan			*relaych;
+		} log;
 	};
 };
 

drivers/net/wwan/t7xx/t7xx_port_proxy.c

@@ -70,6 +70,18 @@ static const struct t7xx_port_conf t7xx_md_port_conf[] = {
 		.name = "MBIM",
 		.port_type = WWAN_PORT_MBIM,
 	}, {
+#ifdef CONFIG_WWAN_DEBUGFS
+		.tx_ch = PORT_CH_MD_LOG_TX,
+		.rx_ch = PORT_CH_MD_LOG_RX,
+		.txq_index = 7,
+		.rxq_index = 7,
+		.txq_exp_index = 7,
+		.rxq_exp_index = 7,
+		.path_id = CLDMA_ID_MD,
+		.ops = &t7xx_trace_port_ops,
+		.name = "mdlog",
+	}, {
+#endif
 		.tx_ch = PORT_CH_CONTROL_TX,
 		.rx_ch = PORT_CH_CONTROL_RX,
 		.txq_index = Q_IDX_CTRL,

drivers/net/wwan/t7xx/t7xx_port_proxy.h

@@ -87,6 +87,10 @@ struct ctrl_msg_header {
 extern struct port_ops wwan_sub_port_ops;
 extern struct port_ops ctl_port_ops;
 
+#ifdef CONFIG_WWAN_DEBUGFS
+extern struct port_ops t7xx_trace_port_ops;
+#endif
+
 void t7xx_port_proxy_reset(struct port_proxy *port_prox);
 void t7xx_port_proxy_uninit(struct port_proxy *port_prox);
 int t7xx_port_proxy_init(struct t7xx_modem *md);

drivers/net/wwan/t7xx/t7xx_port_trace.c

@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2022 Intel Corporation.
+ */
+
+#include <linux/debugfs.h>
+#include <linux/relay.h>
+#include <linux/skbuff.h>
+#include <linux/wwan.h>
+
+#include "t7xx_port.h"
+#include "t7xx_port_proxy.h"
+#include "t7xx_state_monitor.h"
+
+#define T7XX_TRC_SUB_BUFF_SIZE		131072
+#define T7XX_TRC_N_SUB_BUFF		32
+
+static struct dentry *t7xx_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);
+}
+
+static int t7xx_trace_remove_buf_file_handler(struct dentry *dentry)
+{
+	debugfs_remove(dentry);
+	return 0;
+}
+
+static int t7xx_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;
+}
+
+static struct rchan_callbacks relay_callbacks = {
+	.subbuf_start = t7xx_trace_subbuf_start_handler,
+	.create_buf_file = t7xx_trace_create_buf_file_handler,
+	.remove_buf_file = t7xx_trace_remove_buf_file_handler,
+};
+
+static void t7xx_trace_port_uninit(struct t7xx_port *port)
+{
+	struct dentry *debugfs_dir = port->t7xx_dev->debugfs_dir;
+	struct rchan *relaych = port->log.relaych;
+
+	if (!relaych)
+		return;
+
+	relay_close(relaych);
+	debugfs_remove_recursive(debugfs_dir);
+}
+
+static int t7xx_trace_port_recv_skb(struct t7xx_port *port, struct sk_buff *skb)
+{
+	struct rchan *relaych = port->log.relaych;
+
+	if (!relaych)
+		return -EINVAL;
+
+	relay_write(relaych, skb->data, skb->len);
+	dev_kfree_skb(skb);
+	return 0;
+}
+
+static void t7xx_port_trace_md_state_notify(struct t7xx_port *port, unsigned int state)
+{
+	struct rchan *relaych = port->log.relaych;
+	struct dentry *debugfs_wwan_dir;
+	struct dentry *debugfs_dir;
+
+	if (state != MD_STATE_READY || relaych)
+		return;
+
+	debugfs_wwan_dir = wwan_get_debugfs_dir(port->dev);
+	if (IS_ERR(debugfs_wwan_dir))
+		return;
+
+	debugfs_dir = debugfs_create_dir(KBUILD_MODNAME, debugfs_wwan_dir);
+	if (IS_ERR_OR_NULL(debugfs_dir)) {
+		wwan_put_debugfs_dir(debugfs_wwan_dir);
+		dev_err(port->dev, "Unable to create debugfs for trace");
+		return;
+	}
+
+	relaych = relay_open("relay_ch", debugfs_dir, T7XX_TRC_SUB_BUFF_SIZE,
+			     T7XX_TRC_N_SUB_BUFF, &relay_callbacks, NULL);
+	if (!relaych)
+		goto err_rm_debugfs_dir;
+
+	wwan_put_debugfs_dir(debugfs_wwan_dir);
+	port->log.relaych = relaych;
+	port->t7xx_dev->debugfs_dir = debugfs_dir;
+	return;
+
+err_rm_debugfs_dir:
+	debugfs_remove_recursive(debugfs_dir);
+	wwan_put_debugfs_dir(debugfs_wwan_dir);
+	dev_err(port->dev, "Unable to create trace port %s", port->port_conf->name);
+}
+
+struct port_ops t7xx_trace_port_ops = {
+	.recv_skb = t7xx_trace_port_recv_skb,
+	.uninit = t7xx_trace_port_uninit,
+	.md_state_notify = t7xx_port_trace_md_state_notify,
+};