Re: [PATCH v6 1/5] 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 <redacted>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/net/wan/Kconfig        |  12 +
 drivers/net/wan/Makefile       |   1 +
 drivers/net/wan/fsl_qmc_hdlc.c | 413 +++++++++++++++++++++++++++++++++
 3 files changed, 426 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..90063a92209e
--- /dev/null
+++ b/drivers/net/wan/fsl_qmc_hdlc.c

@@ -0,0 +1,413 @@
+// 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 = 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++;