[PATCH v5 1/5] net: wan: Add support for QMC HDLC

Herve Codina
2024-02-29T14:16:14Z

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>
---
drivers/net/wan/Kconfig | 12 +
drivers/net/wan/Makefile | 1 +
drivers/net/wan/fsl_qmc_hdlc.c | 409 +++++++++++++++++++++++++++++++++
3 files changed, 422 insertions(+)
create mode 100644 drivers/net/wan/fsl_qmc_hdlc.c

diff --git a/drivers/net/wan/Kconfig b/drivers/net/wan/Kconfig
index 7dda87756d3f..31ab2136cdf1 100644
--- a/drivers/net/wan/Kconfig
+++ b/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
diff --git a/drivers/net/wan/Makefile b/drivers/net/wan/Makefile
index 8119b49d1da9..00e9b7ee1e01 100644
--- a/drivers/net/wan/Makefile
+++ b/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

diff --git a/drivers/net/wan/fsl_qmc_hdlc.c b/drivers/net/wan/fsl_qmc_hdlc.c
new file mode 100644
index 000000000000..b9e067101171
--- /dev/null
+++ b/drivers/net/wan/fsl_qmc_hdlc.c
@@ -0,0 +1,409 @@
+// 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/cleanup.h>
+#include <linux/dma-mapping.h>
+#include <linux/hdlc.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.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 = desc->netdev;
+ struct qmc_hdlc *qmc_hdlc = netdev_to_qmc_hdlc(netdev);
+ int ret;
+
+ 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 = desc->netdev;
+ struct qmc_hdlc *qmc_hdlc = netdev_to_qmc_hdlc(netdev);
+ struct sk_buff *skb;
+
+ 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);
+ 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:
+ 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");
--
2.43.0