soc: qcom: ipa: modem and microcontroller

This patch includes code implementing the modem functionality.
There are several communication paths between the AP and modem,
separate from the main data path provided by IPA.  SMP2P provides
primitive messaging and interrupt capability, and QMI allows more
complex out-of-band messaging to occur between entities on the AP
and modem.  (SMP2P and QMI support are added by the next patch.)
Management of these (plus the network device implementing the data
path) is done by code within "ipa_modem.c".

Sort of unrelated, this patch also includes the code supporting the
microcontroller CPU present on the IPA.  The microcontroller can be
used to implement special handling of packets, but at this time we
don't support that.  Still, it is a component that needs to be
initialized, and in the event of a crash we need to do some
synchronization between the AP and the microcontroller.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 383 insertions, 0 deletions

diff --git a/drivers/net/ipa/ipa_modem.c b/drivers/net/ipa/ipa_modem.c
new file mode 100644
index 000000000000..039afc8c608e
--- /dev/null
+++ b/drivers/net/ipa/ipa_modem.c
@@ -0,0 +1,383 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/* Copyright (c) 2014-2018, The Linux Foundation. All rights reserved.
+ * Copyright (C) 2018-2020 Linaro Ltd.
+ */
+
+#include <linux/errno.h>
+#include <linux/if_arp.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/if_rmnet.h>
+#include <linux/remoteproc/qcom_q6v5_ipa_notify.h>
+
+#include "ipa.h"
+#include "ipa_data.h"
+#include "ipa_endpoint.h"
+#include "ipa_table.h"
+#include "ipa_mem.h"
+#include "ipa_modem.h"
+#include "ipa_smp2p.h"
+#include "ipa_qmi.h"
+
+#define IPA_NETDEV_NAME		"rmnet_ipa%d"
+#define IPA_NETDEV_TAILROOM	0	/* for padding by mux layer */
+#define IPA_NETDEV_TIMEOUT	10	/* seconds */
+
+enum ipa_modem_state {
+	IPA_MODEM_STATE_STOPPED	= 0,
+	IPA_MODEM_STATE_STARTING,
+	IPA_MODEM_STATE_RUNNING,
+	IPA_MODEM_STATE_STOPPING,
+};
+
+/** struct ipa_priv - IPA network device private data */
+struct ipa_priv {
+	struct ipa *ipa;
+};
+
+/** ipa_open() - Opens the modem network interface */
+static int ipa_open(struct net_device *netdev)
+{
+	struct ipa_priv *priv = netdev_priv(netdev);
+	struct ipa *ipa = priv->ipa;
+	int ret;
+
+	ret = ipa_endpoint_enable_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]);
+	if (ret)
+		return ret;
+	ret = ipa_endpoint_enable_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]);
+	if (ret)
+		goto err_disable_tx;
+
+	netif_start_queue(netdev);
+
+	return 0;
+
+err_disable_tx:
+	ipa_endpoint_disable_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]);
+
+	return ret;
+}
+
+/** ipa_stop() - Stops the modem network interface. */
+static int ipa_stop(struct net_device *netdev)
+{
+	struct ipa_priv *priv = netdev_priv(netdev);
+	struct ipa *ipa = priv->ipa;
+
+	netif_stop_queue(netdev);
+
+	ipa_endpoint_disable_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]);
+	ipa_endpoint_disable_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]);
+
+	return 0;
+}
+
+/** ipa_start_xmit() - Transmits an skb.
+ * @skb: skb to be transmitted
+ * @dev: network device
+ *
+ * Return codes:
+ * NETDEV_TX_OK: Success
+ * NETDEV_TX_BUSY: Error while transmitting the skb. Try again later
+ */
+static int ipa_start_xmit(struct sk_buff *skb, struct net_device *netdev)
+{
+	struct net_device_stats *stats = &netdev->stats;
+	struct ipa_priv *priv = netdev_priv(netdev);
+	struct ipa_endpoint *endpoint;
+	struct ipa *ipa = priv->ipa;
+	u32 skb_len = skb->len;
+	int ret;
+
+	if (!skb_len)
+		goto err_drop_skb;
+
+	endpoint = ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX];
+	if (endpoint->data->qmap && skb->protocol != htons(ETH_P_MAP))
+		goto err_drop_skb;
+
+	ret = ipa_endpoint_skb_tx(endpoint, skb);
+	if (ret) {
+		if (ret != -E2BIG)
+			return NETDEV_TX_BUSY;
+		goto err_drop_skb;
+	}
+
+	stats->tx_packets++;
+	stats->tx_bytes += skb_len;
+
+	return NETDEV_TX_OK;
+
+err_drop_skb:
+	dev_kfree_skb_any(skb);
+	stats->tx_dropped++;
+
+	return NETDEV_TX_OK;
+}
+
+void ipa_modem_skb_rx(struct net_device *netdev, struct sk_buff *skb)
+{
+	struct net_device_stats *stats = &netdev->stats;
+
+	if (skb) {
+		skb->dev = netdev;
+		skb->protocol = htons(ETH_P_MAP);
+		stats->rx_packets++;
+		stats->rx_bytes += skb->len;
+
+		(void)netif_receive_skb(skb);
+	} else {
+		stats->rx_dropped++;
+	}
+}
+
+static const struct net_device_ops ipa_modem_ops = {
+	.ndo_open	= ipa_open,
+	.ndo_stop	= ipa_stop,
+	.ndo_start_xmit	= ipa_start_xmit,
+};
+
+/** ipa_modem_netdev_setup() - netdev setup function for the modem */
+static void ipa_modem_netdev_setup(struct net_device *netdev)
+{
+	netdev->netdev_ops = &ipa_modem_ops;
+	ether_setup(netdev);
+	/* No header ops (override value set by ether_setup()) */
+	netdev->header_ops = NULL;
+	netdev->type = ARPHRD_RAWIP;
+	netdev->hard_header_len = 0;
+	netdev->max_mtu = IPA_MTU;
+	netdev->mtu = netdev->max_mtu;
+	netdev->addr_len = 0;
+	netdev->flags &= ~(IFF_BROADCAST | IFF_MULTICAST);
+	/* The endpoint is configured for QMAP */
+	netdev->needed_headroom = sizeof(struct rmnet_map_header);
+	netdev->needed_tailroom = IPA_NETDEV_TAILROOM;
+	netdev->watchdog_timeo = IPA_NETDEV_TIMEOUT * HZ;
+	netdev->hw_features = NETIF_F_SG;
+}
+
+/** ipa_modem_suspend() - suspend callback
+ * @netdev:	Network device
+ *
+ * Suspend the modem's endpoints.
+ */
+void ipa_modem_suspend(struct net_device *netdev)
+{
+	struct ipa_priv *priv = netdev_priv(netdev);
+	struct ipa *ipa = priv->ipa;
+
+	netif_stop_queue(netdev);
+
+	ipa_endpoint_suspend_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]);
+	ipa_endpoint_suspend_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]);
+}
+
+/** ipa_modem_resume() - resume callback for runtime_pm
+ * @dev: pointer to device
+ *
+ * Resume the modem's endpoints.
+ */
+void ipa_modem_resume(struct net_device *netdev)
+{
+	struct ipa_priv *priv = netdev_priv(netdev);
+	struct ipa *ipa = priv->ipa;
+
+	ipa_endpoint_resume_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]);
+	ipa_endpoint_resume_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]);
+
+	netif_wake_queue(netdev);
+}
+
+int ipa_modem_start(struct ipa *ipa)
+{
+	enum ipa_modem_state state;
+	struct net_device *netdev;
+	struct ipa_priv *priv;
+	int ret;
+
+	/* Only attempt to start the modem if it's stopped */
+	state = atomic_cmpxchg(&ipa->modem_state, IPA_MODEM_STATE_STOPPED,
+			       IPA_MODEM_STATE_STARTING);
+
+	/* Silently ignore attempts when running, or when changing state */
+	if (state != IPA_MODEM_STATE_STOPPED)
+		return 0;
+
+	netdev = alloc_netdev(sizeof(struct ipa_priv), IPA_NETDEV_NAME,
+			      NET_NAME_UNKNOWN, ipa_modem_netdev_setup);
+	if (!netdev) {
+		ret = -ENOMEM;
+		goto out_set_state;
+	}
+
+	ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]->netdev = netdev;
+	ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]->netdev = netdev;
+
+	priv = netdev_priv(netdev);
+	priv->ipa = ipa;
+
+	ret = register_netdev(netdev);
+	if (ret)
+		free_netdev(netdev);
+	else
+		ipa->modem_netdev = netdev;
+
+out_set_state:
+	if (ret)
+		atomic_set(&ipa->modem_state, IPA_MODEM_STATE_STOPPED);
+	else
+		atomic_set(&ipa->modem_state, IPA_MODEM_STATE_RUNNING);
+	smp_mb__after_atomic();
+
+	return ret;
+}
+
+int ipa_modem_stop(struct ipa *ipa)
+{
+	struct net_device *netdev = ipa->modem_netdev;
+	enum ipa_modem_state state;
+	int ret;
+
+	/* Only attempt to stop the modem if it's running */
+	state = atomic_cmpxchg(&ipa->modem_state, IPA_MODEM_STATE_RUNNING,
+			       IPA_MODEM_STATE_STOPPING);
+
+	/* Silently ignore attempts when already stopped */
+	if (state == IPA_MODEM_STATE_STOPPED)
+		return 0;
+
+	/* If we're somewhere between stopped and starting, we're busy */
+	if (state != IPA_MODEM_STATE_RUNNING)
+		return -EBUSY;
+
+	/* Prevent the modem from triggering a call to ipa_setup() */
+	ipa_smp2p_disable(ipa);
+
+	if (netdev) {
+		/* Stop the queue and disable the endpoints if it's open */
+		ret = ipa_stop(netdev);
+		if (ret)
+			goto out_set_state;
+
+		ipa->modem_netdev = NULL;
+		unregister_netdev(netdev);
+		free_netdev(netdev);
+	} else {
+		ret = 0;
+	}
+
+out_set_state:
+	if (ret)
+		atomic_set(&ipa->modem_state, IPA_MODEM_STATE_RUNNING);
+	else
+		atomic_set(&ipa->modem_state, IPA_MODEM_STATE_STOPPED);
+	smp_mb__after_atomic();
+
+	return ret;
+}
+
+/* Treat a "clean" modem stop the same as a crash */
+static void ipa_modem_crashed(struct ipa *ipa)
+{
+	struct device *dev = &ipa->pdev->dev;
+	int ret;
+
+	ipa_endpoint_modem_pause_all(ipa, true);
+
+	ipa_endpoint_modem_hol_block_clear_all(ipa);
+
+	ipa_table_reset(ipa, true);
+
+	ret = ipa_table_hash_flush(ipa);
+	if (ret)
+		dev_err(dev, "error %d flushing hash cahces\n", ret);
+
+	ret = ipa_endpoint_modem_exception_reset_all(ipa);
+	if (ret)
+		dev_err(dev, "error %d resetting exception endpoint",
+			ret);
+
+	ipa_endpoint_modem_pause_all(ipa, false);
+
+	ret = ipa_modem_stop(ipa);
+	if (ret)
+		dev_err(dev, "error %d stopping modem", ret);
+
+	/* Now prepare for the next modem boot */
+	ret = ipa_mem_zero_modem(ipa);
+	if (ret)
+		dev_err(dev, "error %d zeroing modem memory regions\n", ret);
+}
+
+static void ipa_modem_notify(void *data, enum qcom_rproc_event event)
+{
+	struct ipa *ipa = data;
+	struct device *dev;
+
+	dev = &ipa->pdev->dev;
+	switch (event) {
+	case MODEM_STARTING:
+		dev_info(dev, "received modem starting event\n");
+		ipa_smp2p_notify_reset(ipa);
+		break;
+
+	case MODEM_RUNNING:
+		dev_info(dev, "received modem running event\n");
+		break;
+
+	case MODEM_STOPPING:
+	case MODEM_CRASHED:
+		dev_info(dev, "received modem %s event\n",
+			 event == MODEM_STOPPING ? "stopping"
+						 : "crashed");
+		if (ipa->setup_complete)
+			ipa_modem_crashed(ipa);
+		break;
+
+	case MODEM_OFFLINE:
+		dev_info(dev, "received modem offline event\n");
+		break;
+
+	case MODEM_REMOVING:
+		dev_info(dev, "received modem stopping event\n");
+		break;
+
+	default:
+		dev_err(&ipa->pdev->dev, "unrecognized event %u\n", event);
+		break;
+	}
+}
+
+int ipa_modem_init(struct ipa *ipa, bool modem_init)
+{
+	return ipa_smp2p_init(ipa, modem_init);
+}
+
+void ipa_modem_exit(struct ipa *ipa)
+{
+	ipa_smp2p_exit(ipa);
+}
+
+int ipa_modem_config(struct ipa *ipa)
+{
+	return qcom_register_ipa_notify(ipa->modem_rproc, ipa_modem_notify,
+					ipa);
+}
+
+void ipa_modem_deconfig(struct ipa *ipa)
+{
+	qcom_deregister_ipa_notify(ipa->modem_rproc);
+}
+
+int ipa_modem_setup(struct ipa *ipa)
+{
+	return ipa_qmi_setup(ipa);
+}
+
+void ipa_modem_teardown(struct ipa *ipa)
+{
+	ipa_qmi_teardown(ipa);
+}