net: wan: Add support for QMC HDLC

The QMC HDLC driver provides support for HDLC using the QMC (QUICC
Multichannel Controller) to transfer the HDLC data.
Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wan/Kconfig

@@ -197,6 +197,18 @@ config FARSYNC
 	  To compile this driver as a module, choose M here: the
 	  module will be called farsync.
 
+config FSL_QMC_HDLC
+	tristate "Freescale QMC HDLC support"
+	depends on HDLC
+	depends on CPM_QMC
+	help
+	  HDLC support using the Freescale QUICC Multichannel Controller (QMC).
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called fsl_qmc_hdlc.
+
+	  If unsure, say N.
+
 config FSL_UCC_HDLC
 	tristate "Freescale QUICC Engine HDLC support"
 	depends on HDLC

drivers/net/wan/Makefile

@@ -25,6 +25,7 @@ obj-$(CONFIG_WANXL)		+= wanxl.o
 obj-$(CONFIG_PCI200SYN)		+= pci200syn.o
 obj-$(CONFIG_PC300TOO)		+= pc300too.o
 obj-$(CONFIG_IXP4XX_HSS)	+= ixp4xx_hss.o
+obj-$(CONFIG_FSL_QMC_HDLC)	+= fsl_qmc_hdlc.o
 obj-$(CONFIG_FSL_UCC_HDLC)	+= fsl_ucc_hdlc.o
 obj-$(CONFIG_SLIC_DS26522)	+= slic_ds26522.o
 

drivers/net/wan/fsl_qmc_hdlc.c

+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Freescale QMC HDLC Device Driver
+ *
+ * Copyright 2023 CS GROUP France
+ *
+ * Author: Herve Codina <herve.codina@bootlin.com>
+ */
+
+#include <linux/array_size.h>
+#include <linux/bug.h>
+#include <linux/cleanup.h>
+#include <linux/dma-mapping.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/hdlc.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+
+#include <soc/fsl/qe/qmc.h>
+
+struct qmc_hdlc_desc {
+	struct net_device *netdev;
+	struct sk_buff *skb; /* NULL if the descriptor is not in use */
+	dma_addr_t dma_addr;
+	size_t dma_size;
+};
+
+struct qmc_hdlc {
+	struct device *dev;
+	struct qmc_chan *qmc_chan;
+	struct net_device *netdev;
+	bool is_crc32;
+	spinlock_t tx_lock; /* Protect tx descriptors */
+	struct qmc_hdlc_desc tx_descs[8];
+	unsigned int tx_out;
+	struct qmc_hdlc_desc rx_descs[4];
+};
+
+static struct qmc_hdlc *netdev_to_qmc_hdlc(struct net_device *netdev)
+{
+	return dev_to_hdlc(netdev)->priv;
+}
+
+static int qmc_hdlc_recv_queue(struct qmc_hdlc *qmc_hdlc, struct qmc_hdlc_desc *desc, size_t size);
+
+#define QMC_HDLC_RX_ERROR_FLAGS				\
+	(QMC_RX_FLAG_HDLC_OVF | QMC_RX_FLAG_HDLC_UNA |	\
+	 QMC_RX_FLAG_HDLC_CRC | QMC_RX_FLAG_HDLC_ABORT)
+
+static void qmc_hcld_recv_complete(void *context, size_t length, unsigned int flags)
+{
+	struct qmc_hdlc_desc *desc = context;
+	struct net_device *netdev;
+	struct qmc_hdlc *qmc_hdlc;
+	int ret;
+
+	netdev = desc->netdev;
+	qmc_hdlc = netdev_to_qmc_hdlc(netdev);
+
+	dma_unmap_single(qmc_hdlc->dev, desc->dma_addr, desc->dma_size, DMA_FROM_DEVICE);
+
+	if (flags & QMC_HDLC_RX_ERROR_FLAGS) {
+		netdev->stats.rx_errors++;
+		if (flags & QMC_RX_FLAG_HDLC_OVF) /* Data overflow */
+			netdev->stats.rx_over_errors++;
+		if (flags & QMC_RX_FLAG_HDLC_UNA) /* bits received not multiple of 8 */
+			netdev->stats.rx_frame_errors++;
+		if (flags & QMC_RX_FLAG_HDLC_ABORT) /* Received an abort sequence */
+			netdev->stats.rx_frame_errors++;
+		if (flags & QMC_RX_FLAG_HDLC_CRC) /* CRC error */
+			netdev->stats.rx_crc_errors++;
+		kfree_skb(desc->skb);
+	} else {
+		netdev->stats.rx_packets++;
+		netdev->stats.rx_bytes += length;
+
+		skb_put(desc->skb, length);
+		desc->skb->protocol = hdlc_type_trans(desc->skb, netdev);
+		netif_rx(desc->skb);
+	}
+
+	/* Re-queue a transfer using the same descriptor */
+	ret = qmc_hdlc_recv_queue(qmc_hdlc, desc, desc->dma_size);
+	if (ret) {
+		dev_err(qmc_hdlc->dev, "queue recv desc failed (%d)\n", ret);
+		netdev->stats.rx_errors++;
+	}
+}
+
+static int qmc_hdlc_recv_queue(struct qmc_hdlc *qmc_hdlc, struct qmc_hdlc_desc *desc, size_t size)
+{
+	int ret;
+
+	desc->skb = dev_alloc_skb(size);
+	if (!desc->skb)
+		return -ENOMEM;
+
+	desc->dma_size = size;
+	desc->dma_addr = dma_map_single(qmc_hdlc->dev, desc->skb->data,
+					desc->dma_size, DMA_FROM_DEVICE);
+	ret = dma_mapping_error(qmc_hdlc->dev, desc->dma_addr);
+	if (ret)
+		goto free_skb;
+
+	ret = qmc_chan_read_submit(qmc_hdlc->qmc_chan, desc->dma_addr, desc->dma_size,
+				   qmc_hcld_recv_complete, desc);
+	if (ret)
+		goto dma_unmap;
+
+	return 0;
+
+dma_unmap:
+	dma_unmap_single(qmc_hdlc->dev, desc->dma_addr, desc->dma_size, DMA_FROM_DEVICE);
+free_skb:
+	kfree_skb(desc->skb);
+	desc->skb = NULL;
+	return ret;
+}
+
+static void qmc_hdlc_xmit_complete(void *context)
+{
+	struct qmc_hdlc_desc *desc = context;
+	struct net_device *netdev;
+	struct qmc_hdlc *qmc_hdlc;
+	struct sk_buff *skb;
+
+	netdev = desc->netdev;
+	qmc_hdlc = netdev_to_qmc_hdlc(netdev);
+
+	scoped_guard(spinlock_irqsave, &qmc_hdlc->tx_lock) {
+		dma_unmap_single(qmc_hdlc->dev, desc->dma_addr, desc->dma_size, DMA_TO_DEVICE);
+		skb = desc->skb;
+		desc->skb = NULL; /* Release the descriptor */
+		if (netif_queue_stopped(netdev))
+			netif_wake_queue(netdev);
+	}
+
+	netdev->stats.tx_packets++;
+	netdev->stats.tx_bytes += skb->len;
+
+	dev_consume_skb_any(skb);
+}
+
+static int qmc_hdlc_xmit_queue(struct qmc_hdlc *qmc_hdlc, struct qmc_hdlc_desc *desc)
+{
+	int ret;
+
+	desc->dma_addr = dma_map_single(qmc_hdlc->dev, desc->skb->data,
+					desc->dma_size, DMA_TO_DEVICE);
+	ret = dma_mapping_error(qmc_hdlc->dev, desc->dma_addr);
+	if (ret) {
+		dev_err(qmc_hdlc->dev, "failed to map skb\n");
+		return ret;
+	}
+
+	ret = qmc_chan_write_submit(qmc_hdlc->qmc_chan, desc->dma_addr, desc->dma_size,
+				    qmc_hdlc_xmit_complete, desc);
+	if (ret) {
+		dma_unmap_single(qmc_hdlc->dev, desc->dma_addr, desc->dma_size, DMA_TO_DEVICE);
+		dev_err(qmc_hdlc->dev, "qmc chan write returns %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static netdev_tx_t qmc_hdlc_xmit(struct sk_buff *skb, struct net_device *netdev)
+{
+	struct qmc_hdlc *qmc_hdlc = netdev_to_qmc_hdlc(netdev);
+	struct qmc_hdlc_desc *desc;
+	int err;
+
+	guard(spinlock_irqsave)(&qmc_hdlc->tx_lock);
+
+	desc = &qmc_hdlc->tx_descs[qmc_hdlc->tx_out];
+	if (WARN_ONCE(desc->skb, "No tx descriptors available\n")) {
+		/* Should never happen.
+		 * Previous xmit should have already stopped the queue.
+		 */
+		netif_stop_queue(netdev);
+		return NETDEV_TX_BUSY;
+	}
+
+	desc->netdev = netdev;
+	desc->dma_size = skb->len;
+	desc->skb = skb;
+	err = qmc_hdlc_xmit_queue(qmc_hdlc, desc);
+	if (err) {
+		desc->skb = NULL; /* Release the descriptor */
+		if (err == -EBUSY) {
+			netif_stop_queue(netdev);
+			return NETDEV_TX_BUSY;
+		}
+		dev_kfree_skb(skb);
+		netdev->stats.tx_dropped++;
+		return NETDEV_TX_OK;
+	}
+
+	qmc_hdlc->tx_out = (qmc_hdlc->tx_out + 1) % ARRAY_SIZE(qmc_hdlc->tx_descs);
+
+	if (qmc_hdlc->tx_descs[qmc_hdlc->tx_out].skb)
+		netif_stop_queue(netdev);
+
+	return NETDEV_TX_OK;
+}
+
+static int qmc_hdlc_open(struct net_device *netdev)
+{
+	struct qmc_hdlc *qmc_hdlc = netdev_to_qmc_hdlc(netdev);
+	struct qmc_chan_param chan_param;
+	struct qmc_hdlc_desc *desc;
+	int ret;
+	int i;
+
+	ret = hdlc_open(netdev);
+	if (ret)
+		return ret;
+
+	chan_param.mode = QMC_HDLC;
+	/* HDLC_MAX_MRU + 4 for the CRC
+	 * HDLC_MAX_MRU + 4 + 8 for the CRC and some extraspace needed by the QMC
+	 */
+	chan_param.hdlc.max_rx_buf_size = HDLC_MAX_MRU + 4 + 8;
+	chan_param.hdlc.max_rx_frame_size = HDLC_MAX_MRU + 4;
+	chan_param.hdlc.is_crc32 = qmc_hdlc->is_crc32;
+	ret = qmc_chan_set_param(qmc_hdlc->qmc_chan, &chan_param);
+	if (ret) {
+		dev_err(qmc_hdlc->dev, "failed to set param (%d)\n", ret);
+		goto hdlc_close;
+	}
+
+	/* Queue as many recv descriptors as possible */
+	for (i = 0; i < ARRAY_SIZE(qmc_hdlc->rx_descs); i++) {
+		desc = &qmc_hdlc->rx_descs[i];
+
+		desc->netdev = netdev;
+		ret = qmc_hdlc_recv_queue(qmc_hdlc, desc, chan_param.hdlc.max_rx_buf_size);
+		if (ret == -EBUSY && i != 0)
+			break; /* We use all the QMC chan capability */
+		if (ret)
+			goto free_desc;
+	}
+
+	ret = qmc_chan_start(qmc_hdlc->qmc_chan, QMC_CHAN_ALL);
+	if (ret) {
+		dev_err(qmc_hdlc->dev, "qmc chan start failed (%d)\n", ret);
+		goto free_desc;
+	}
+
+	netif_start_queue(netdev);
+
+	return 0;
+
+free_desc:
+	qmc_chan_reset(qmc_hdlc->qmc_chan, QMC_CHAN_ALL);
+	while (i--) {
+		desc = &qmc_hdlc->rx_descs[i];
+		dma_unmap_single(qmc_hdlc->dev, desc->dma_addr, desc->dma_size,
+				 DMA_FROM_DEVICE);
+		kfree_skb(desc->skb);
+		desc->skb = NULL;
+	}
+hdlc_close:
+	hdlc_close(netdev);
+	return ret;
+}
+
+static int qmc_hdlc_close(struct net_device *netdev)
+{
+	struct qmc_hdlc *qmc_hdlc = netdev_to_qmc_hdlc(netdev);
+	struct qmc_hdlc_desc *desc;
+	int i;
+
+	qmc_chan_stop(qmc_hdlc->qmc_chan, QMC_CHAN_ALL);
+	qmc_chan_reset(qmc_hdlc->qmc_chan, QMC_CHAN_ALL);
+
+	netif_stop_queue(netdev);
+
+	for (i = 0; i < ARRAY_SIZE(qmc_hdlc->tx_descs); i++) {
+		desc = &qmc_hdlc->tx_descs[i];
+		if (!desc->skb)
+			continue;
+		dma_unmap_single(qmc_hdlc->dev, desc->dma_addr, desc->dma_size,
+				 DMA_TO_DEVICE);
+		kfree_skb(desc->skb);
+		desc->skb = NULL;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(qmc_hdlc->rx_descs); i++) {
+		desc = &qmc_hdlc->rx_descs[i];
+		if (!desc->skb)
+			continue;
+		dma_unmap_single(qmc_hdlc->dev, desc->dma_addr, desc->dma_size,
+				 DMA_FROM_DEVICE);
+		kfree_skb(desc->skb);
+		desc->skb = NULL;
+	}
+
+	hdlc_close(netdev);
+	return 0;
+}
+
+static int qmc_hdlc_attach(struct net_device *netdev, unsigned short encoding,
+			   unsigned short parity)
+{
+	struct qmc_hdlc *qmc_hdlc = netdev_to_qmc_hdlc(netdev);
+
+	if (encoding != ENCODING_NRZ)
+		return -EINVAL;
+
+	switch (parity) {
+	case PARITY_CRC16_PR1_CCITT:
+		qmc_hdlc->is_crc32 = false;
+		break;
+	case PARITY_CRC32_PR1_CCITT:
+		qmc_hdlc->is_crc32 = true;
+		break;
+	default:
+		dev_err(qmc_hdlc->dev, "unsupported parity %u\n", parity);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static const struct net_device_ops qmc_hdlc_netdev_ops = {
+	.ndo_open       = qmc_hdlc_open,
+	.ndo_stop       = qmc_hdlc_close,
+	.ndo_start_xmit = hdlc_start_xmit,
+	.ndo_siocwandev	= hdlc_ioctl,
+};
+
+static int qmc_hdlc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct qmc_hdlc *qmc_hdlc;
+	struct qmc_chan_info info;
+	hdlc_device *hdlc;
+	int ret;
+
+	qmc_hdlc = devm_kzalloc(dev, sizeof(*qmc_hdlc), GFP_KERNEL);
+	if (!qmc_hdlc)
+		return -ENOMEM;
+
+	qmc_hdlc->dev = dev;
+	spin_lock_init(&qmc_hdlc->tx_lock);
+
+	qmc_hdlc->qmc_chan = devm_qmc_chan_get_bychild(dev, dev->of_node);
+	if (IS_ERR(qmc_hdlc->qmc_chan))
+		return dev_err_probe(dev, PTR_ERR(qmc_hdlc->qmc_chan),
+				     "get QMC channel failed\n");
+
+	ret = qmc_chan_get_info(qmc_hdlc->qmc_chan, &info);
+	if (ret)
+		return dev_err_probe(dev, ret, "get QMC channel info failed\n");
+
+	if (info.mode != QMC_HDLC)
+		return dev_err_probe(dev, -EINVAL, "QMC chan mode %d is not QMC_HDLC\n",
+				     info.mode);
+
+	qmc_hdlc->netdev = alloc_hdlcdev(qmc_hdlc);
+	if (!qmc_hdlc->netdev)
+		return -ENOMEM;
+
+	hdlc = dev_to_hdlc(qmc_hdlc->netdev);
+	hdlc->attach = qmc_hdlc_attach;
+	hdlc->xmit = qmc_hdlc_xmit;
+	SET_NETDEV_DEV(qmc_hdlc->netdev, dev);
+	qmc_hdlc->netdev->tx_queue_len = ARRAY_SIZE(qmc_hdlc->tx_descs);
+	qmc_hdlc->netdev->netdev_ops = &qmc_hdlc_netdev_ops;
+	ret = register_hdlc_device(qmc_hdlc->netdev);
+	if (ret) {
+		dev_err_probe(dev, ret, "failed to register hdlc device\n");
+		goto free_netdev;
+	}
+
+	platform_set_drvdata(pdev, qmc_hdlc);
+
+	return 0;
+
+free_netdev:
+	free_netdev(qmc_hdlc->netdev);
+	return ret;
+}
+
+static int qmc_hdlc_remove(struct platform_device *pdev)
+{
+	struct qmc_hdlc *qmc_hdlc = platform_get_drvdata(pdev);
+
+	unregister_hdlc_device(qmc_hdlc->netdev);
+	free_netdev(qmc_hdlc->netdev);
+
+	return 0;
+}
+
+static const struct of_device_id qmc_hdlc_id_table[] = {
+	{ .compatible = "fsl,qmc-hdlc" },
+	{} /* sentinel */
+};
+MODULE_DEVICE_TABLE(of, qmc_hdlc_driver);
+
+static struct platform_driver qmc_hdlc_driver = {
+	.driver = {
+		.name = "fsl-qmc-hdlc",
+		.of_match_table = qmc_hdlc_id_table,
+	},
+	.probe = qmc_hdlc_probe,
+	.remove = qmc_hdlc_remove,
+};
+module_platform_driver(qmc_hdlc_driver);
+
+MODULE_AUTHOR("Herve Codina <herve.codina@bootlin.com>");
+MODULE_DESCRIPTION("QMC HDLC driver");
+MODULE_LICENSE("GPL");