Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted

Pull networking updates from Jakub Kicinski:
 "Core:

   - Add dedicated kmem_cache for typical/small skb->head, avoid having
     to access struct page at kfree time, and improve memory use.

   - Introduce sysctl to set default RPS configuration for new netdevs.

   - Define Netlink protocol specification format which can be used to
     describe messages used by each family and auto-generate parsers.
     Add tools for generating kernel data structures and uAPI headers.

   - Expose all net/core sysctls inside netns.

   - Remove 4s sleep in netpoll if carrier is instantly detected on
     boot.

   - Add configurable limit of MDB entries per port, and port-vlan.

   - Continue populating drop reasons throughout the stack.

   - Retire a handful of legacy Qdiscs and classifiers.

  Protocols:

   - Support IPv4 big TCP (TSO frames larger than 64kB).

   - Add IP_LOCAL_PORT_RANGE socket option, to control local port range
     on socket by socket basis.

   - Track and report in procfs number of MPTCP sockets used.

   - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
     manager.

   - IPv6: don't check net.ipv6.route.max_size and rely on garbage
     collection to free memory (similarly to IPv4).

   - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).

   - ICMP: add per-rate limit counters.

   - Add support for user scanning requests in ieee802154.

   - Remove static WEP support.

   - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
     reporting.

   - WiFi 7 EHT channel puncturing support (client & AP).

  BPF:

   - Add a rbtree data structure following the "next-gen data structure"
     precedent set by recently added linked list, that is, by using
     kfunc + kptr instead of adding a new BPF map type.

   - Expose XDP hints via kfuncs with initial support for RX hash and
     timestamp metadata.

   - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
     better support decap on GRE tunnel devices not operating in collect
     metadata.

   - Improve x86 JIT's codegen for PROBE_MEM runtime error checks.

   - Remove the need for trace_printk_lock for bpf_trace_printk and
     bpf_trace_vprintk helpers.

   - Extend libbpf's bpf_tracing.h support for tracing arguments of
     kprobes/uprobes and syscall as a special case.

   - Significantly reduce the search time for module symbols by
     livepatch and BPF.

   - Enable cpumasks to be used as kptrs, which is useful for tracing
     programs tracking which tasks end up running on which CPUs in
     different time intervals.

   - Add support for BPF trampoline on s390x and riscv64.

   - Add capability to export the XDP features supported by the NIC.

   - Add __bpf_kfunc tag for marking kernel functions as kfuncs.

   - Add cgroup.memory=nobpf kernel parameter option to disable BPF
     memory accounting for container environments.

  Netfilter:

   - Remove the CLUSTERIP target. It has been marked as obsolete for
     years, and we still have WARN splats wrt races of the out-of-band
     /proc interface installed by this target.

   - Add 'destroy' commands to nf_tables. They are identical to the
     existing 'delete' commands, but do not return an error if the
     referenced object (set, chain, rule...) did not exist.

  Driver API:

   - Improve cpumask_local_spread() locality to help NICs set the right
     IRQ affinity on AMD platforms.

   - Separate C22 and C45 MDIO bus transactions more clearly.

   - Introduce new DCB table to control DSCP rewrite on egress.

   - Support configuration of Physical Layer Collision Avoidance (PLCA)
     Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
     shared medium Ethernet.

   - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
     preemption of low priority frames by high priority frames.

   - Add support for controlling MACSec offload using netlink SET.

   - Rework devlink instance refcounts to allow registration and
     de-registration under the instance lock. Split the code into
     multiple files, drop some of the unnecessarily granular locks and
     factor out common parts of netlink operation handling.

   - Add TX frame aggregation parameters (for USB drivers).

   - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
     messages with notifications for debug.

   - Allow offloading of UDP NEW connections via act_ct.

   - Add support for per action HW stats in TC.

   - Support hardware miss to TC action (continue processing in SW from
     a specific point in the action chain).

   - Warn if old Wireless Extension user space interface is used with
     modern cfg80211/mac80211 drivers. Do not support Wireless
     Extensions for Wi-Fi 7 devices at all. Everyone should switch to
     using nl80211 interface instead.

   - Improve the CAN bit timing configuration. Use extack to return
     error messages directly to user space, update the SJW handling,
     including the definition of a new default value that will benefit
     CAN-FD controllers, by increasing their oscillator tolerance.

  New hardware / drivers:

   - Ethernet:
      - nVidia BlueField-3 support (control traffic driver)
      - Ethernet support for imx93 SoCs
      - Motorcomm yt8531 gigabit Ethernet PHY
      - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
      - Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
      - Amlogic gxl MDIO mux

   - WiFi:
      - RealTek RTL8188EU (rtl8xxxu)
      - Qualcomm Wi-Fi 7 devices (ath12k)

   - CAN:
      - Renesas R-Car V4H

  Drivers:

   - Bluetooth:
      - Set Per Platform Antenna Gain (PPAG) for Intel controllers.

   - Ethernet NICs:
      - Intel (1G, igc):
         - support TSN / Qbv / packet scheduling features of i226 model
      - Intel (100G, ice):
         - use GNSS subsystem instead of TTY
         - multi-buffer XDP support
         - extend support for GPIO pins to E823 devices
      - nVidia/Mellanox:
         - update the shared buffer configuration on PFC commands
         - implement PTP adjphase function for HW offset control
         - TC support for Geneve and GRE with VF tunnel offload
         - more efficient crypto key management method
         - multi-port eswitch support
      - Netronome/Corigine:
         - add DCB IEEE support
         - support IPsec offloading for NFP3800
      - Freescale/NXP (enetc):
         - support XDP_REDIRECT for XDP non-linear buffers
         - improve reconfig, avoid link flap and waiting for idle
         - support MAC Merge layer
      - Other NICs:
         - sfc/ef100: add basic devlink support for ef100
         - ionic: rx_push mode operation (writing descriptors via MMIO)
         - bnxt: use the auxiliary bus abstraction for RDMA
         - r8169: disable ASPM and reset bus in case of tx timeout
         - cpsw: support QSGMII mode for J721e CPSW9G
         - cpts: support pulse-per-second output
         - ngbe: add an mdio bus driver
         - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
         - r8152: handle devices with FW with NCM support
         - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
         - virtio-net: support multi buffer XDP
         - virtio/vsock: replace virtio_vsock_pkt with sk_buff
         - tsnep: XDP support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add support for latency TLV (in FW control messages)
      - Microchip (sparx5):
         - separate explicit and implicit traffic forwarding rules, make
           the implicit rules always active
         - add support for egress DSCP rewrite
         - IS0 VCAP support (Ingress Classification)
         - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
           etc.)
         - ES2 VCAP support (Egress Access Control)
         - support for Per-Stream Filtering and Policing (802.1Q,
           8.6.5.1)

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - add MAB (port auth) offload support
         - enable PTP receive for mv88e6390
      - NXP (ocelot):
         - support MAC Merge layer
         - support for the the vsc7512 internal copper phys
      - Microchip:
         - lan9303: convert to PHYLINK
         - lan966x: support TC flower filter statistics
         - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
         - lan937x: support Credit Based Shaper configuration
         - ksz9477: support Energy Efficient Ethernet
      - other:
         - qca8k: convert to regmap read/write API, use bulk operations
         - rswitch: Improve TX timestamp accuracy

   - Intel WiFi (iwlwifi):
      - EHT (Wi-Fi 7) rate reporting
      - STEP equalizer support: transfer some STEP (connection to radio
        on platforms with integrated wifi) related parameters from the
        BIOS to the firmware.

   - Qualcomm 802.11ax WiFi (ath11k):
      - IPQ5018 support
      - Fine Timing Measurement (FTM) responder role support
      - channel 177 support

   - MediaTek WiFi (mt76):
      - per-PHY LED support
      - mt7996: EHT (Wi-Fi 7) support
      - Wireless Ethernet Dispatch (WED) reset support
      - switch to using page pool allocator

   - RealTek WiFi (rtw89):
      - support new version of Bluetooth co-existance

   - Mobile:
      - rmnet: support TX aggregation"

* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
  page_pool: add a comment explaining the fragment counter usage
  net: ethtool: fix __ethtool_dev_mm_supported() implementation
  ethtool: pse-pd: Fix double word in comments
  xsk: add linux/vmalloc.h to xsk.c
  sefltests: netdevsim: wait for devlink instance after netns removal
  selftest: fib_tests: Always cleanup before exit
  net/mlx5e: Align IPsec ASO result memory to be as required by hardware
  net/mlx5e: TC, Set CT miss to the specific ct action instance
  net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
  net/mlx5: Refactor tc miss handling to a single function
  net/mlx5: Kconfig: Make tc offload depend on tc skb extension
  net/sched: flower: Support hardware miss to tc action
  net/sched: flower: Move filter handle initialization earlier
  net/sched: cls_api: Support hardware miss to tc action
  net/sched: Rename user cookie and act cookie
  sfc: fix builds without CONFIG_RTC_LIB
  sfc: clean up some inconsistent indentings
  net/mlx4_en: Introduce flexible array to silence overflow warning
  net: lan966x: Fix possible deadlock inside PTP
  net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
  ...

1 files changed, 671 insertions, 0 deletions

diff --git a/drivers/spi/spi-dw-dma.c b/drivers/spi/spi-dw-dma.c
new file mode 100644
index 000000000..ababb910b
--- /dev/null
+++ b/drivers/spi/spi-dw-dma.c
@@ -0,0 +1,671 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Special handling for DW DMA core
+ *
+ * Copyright (c) 2009, 2014 Intel Corporation.
+ */
+
+#include <linux/completion.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/irqreturn.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/platform_data/dma-dw.h>
+#include <linux/spi/spi.h>
+#include <linux/types.h>
+
+#include "spi-dw.h"
+
+#define DW_SPI_RX_BUSY		0
+#define DW_SPI_RX_BURST_LEVEL	16
+#define DW_SPI_TX_BUSY		1
+#define DW_SPI_TX_BURST_LEVEL	16
+
+static bool dw_spi_dma_chan_filter(struct dma_chan *chan, void *param)
+{
+	struct dw_dma_slave *s = param;
+
+	if (s->dma_dev != chan->device->dev)
+		return false;
+
+	chan->private = s;
+	return true;
+}
+
+static void dw_spi_dma_maxburst_init(struct dw_spi *dws)
+{
+	struct dma_slave_caps caps;
+	u32 max_burst, def_burst;
+	int ret;
+
+	def_burst = dws->fifo_len / 2;
+
+	ret = dma_get_slave_caps(dws->rxchan, &caps);
+	if (!ret && caps.max_burst)
+		max_burst = caps.max_burst;
+	else
+		max_burst = DW_SPI_RX_BURST_LEVEL;
+
+	dws->rxburst = min(max_burst, def_burst);
+	dw_writel(dws, DW_SPI_DMARDLR, dws->rxburst - 1);
+
+	ret = dma_get_slave_caps(dws->txchan, &caps);
+	if (!ret && caps.max_burst)
+		max_burst = caps.max_burst;
+	else
+		max_burst = DW_SPI_TX_BURST_LEVEL;
+
+	/*
+	 * Having a Rx DMA channel serviced with higher priority than a Tx DMA
+	 * channel might not be enough to provide a well balanced DMA-based
+	 * SPI transfer interface. There might still be moments when the Tx DMA
+	 * channel is occasionally handled faster than the Rx DMA channel.
+	 * That in its turn will eventually cause the SPI Rx FIFO overflow if
+	 * SPI bus speed is high enough to fill the SPI Rx FIFO in before it's
+	 * cleared by the Rx DMA channel. In order to fix the problem the Tx
+	 * DMA activity is intentionally slowed down by limiting the SPI Tx
+	 * FIFO depth with a value twice bigger than the Tx burst length.
+	 */
+	dws->txburst = min(max_burst, def_burst);
+	dw_writel(dws, DW_SPI_DMATDLR, dws->txburst);
+}
+
+static void dw_spi_dma_sg_burst_init(struct dw_spi *dws)
+{
+	struct dma_slave_caps tx = {0}, rx = {0};
+
+	dma_get_slave_caps(dws->txchan, &tx);
+	dma_get_slave_caps(dws->rxchan, &rx);
+
+	if (tx.max_sg_burst > 0 && rx.max_sg_burst > 0)
+		dws->dma_sg_burst = min(tx.max_sg_burst, rx.max_sg_burst);
+	else if (tx.max_sg_burst > 0)
+		dws->dma_sg_burst = tx.max_sg_burst;
+	else if (rx.max_sg_burst > 0)
+		dws->dma_sg_burst = rx.max_sg_burst;
+	else
+		dws->dma_sg_burst = 0;
+}
+
+static int dw_spi_dma_init_mfld(struct device *dev, struct dw_spi *dws)
+{
+	struct dw_dma_slave dma_tx = { .dst_id = 1 }, *tx = &dma_tx;
+	struct dw_dma_slave dma_rx = { .src_id = 0 }, *rx = &dma_rx;
+	struct pci_dev *dma_dev;
+	dma_cap_mask_t mask;
+
+	/*
+	 * Get pci device for DMA controller, currently it could only
+	 * be the DMA controller of Medfield
+	 */
+	dma_dev = pci_get_device(PCI_VENDOR_ID_INTEL, 0x0827, NULL);
+	if (!dma_dev)
+		return -ENODEV;
+
+	dma_cap_zero(mask);
+	dma_cap_set(DMA_SLAVE, mask);
+
+	/* 1. Init rx channel */
+	rx->dma_dev = &dma_dev->dev;
+	dws->rxchan = dma_request_channel(mask, dw_spi_dma_chan_filter, rx);
+	if (!dws->rxchan)
+		goto err_exit;
+
+	/* 2. Init tx channel */
+	tx->dma_dev = &dma_dev->dev;
+	dws->txchan = dma_request_channel(mask, dw_spi_dma_chan_filter, tx);
+	if (!dws->txchan)
+		goto free_rxchan;
+
+	dws->master->dma_rx = dws->rxchan;
+	dws->master->dma_tx = dws->txchan;
+
+	init_completion(&dws->dma_completion);
+
+	dw_spi_dma_maxburst_init(dws);
+
+	dw_spi_dma_sg_burst_init(dws);
+
+	pci_dev_put(dma_dev);
+
+	return 0;
+
+free_rxchan:
+	dma_release_channel(dws->rxchan);
+	dws->rxchan = NULL;
+err_exit:
+	pci_dev_put(dma_dev);
+	return -EBUSY;
+}
+
+static int dw_spi_dma_init_generic(struct device *dev, struct dw_spi *dws)
+{
+	int ret;
+
+	dws->rxchan = dma_request_chan(dev, "rx");
+	if (IS_ERR(dws->rxchan)) {
+		ret = PTR_ERR(dws->rxchan);
+		dws->rxchan = NULL;
+		goto err_exit;
+	}
+
+	dws->txchan = dma_request_chan(dev, "tx");
+	if (IS_ERR(dws->txchan)) {
+		ret = PTR_ERR(dws->txchan);
+		dws->txchan = NULL;
+		goto free_rxchan;
+	}
+
+	dws->master->dma_rx = dws->rxchan;
+	dws->master->dma_tx = dws->txchan;
+
+	init_completion(&dws->dma_completion);
+
+	dw_spi_dma_maxburst_init(dws);
+
+	dw_spi_dma_sg_burst_init(dws);
+
+	return 0;
+
+free_rxchan:
+	dma_release_channel(dws->rxchan);
+	dws->rxchan = NULL;
+err_exit:
+	return ret;
+}
+
+static void dw_spi_dma_exit(struct dw_spi *dws)
+{
+	if (dws->txchan) {
+		dmaengine_terminate_sync(dws->txchan);
+		dma_release_channel(dws->txchan);
+	}
+
+	if (dws->rxchan) {
+		dmaengine_terminate_sync(dws->rxchan);
+		dma_release_channel(dws->rxchan);
+	}
+}
+
+static irqreturn_t dw_spi_dma_transfer_handler(struct dw_spi *dws)
+{
+	dw_spi_check_status(dws, false);
+
+	complete(&dws->dma_completion);
+
+	return IRQ_HANDLED;
+}
+
+static bool dw_spi_can_dma(struct spi_controller *master,
+			   struct spi_device *spi, struct spi_transfer *xfer)
+{
+	struct dw_spi *dws = spi_controller_get_devdata(master);
+
+	return xfer->len > dws->fifo_len;
+}
+
+static enum dma_slave_buswidth dw_spi_dma_convert_width(u8 n_bytes)
+{
+	if (n_bytes == 1)
+		return DMA_SLAVE_BUSWIDTH_1_BYTE;
+	else if (n_bytes == 2)
+		return DMA_SLAVE_BUSWIDTH_2_BYTES;
+
+	return DMA_SLAVE_BUSWIDTH_UNDEFINED;
+}
+
+static int dw_spi_dma_wait(struct dw_spi *dws, unsigned int len, u32 speed)
+{
+	unsigned long long ms;
+
+	ms = len * MSEC_PER_SEC * BITS_PER_BYTE;
+	do_div(ms, speed);
+	ms += ms + 200;
+
+	if (ms > UINT_MAX)
+		ms = UINT_MAX;
+
+	ms = wait_for_completion_timeout(&dws->dma_completion,
+					 msecs_to_jiffies(ms));
+
+	if (ms == 0) {
+		dev_err(&dws->master->cur_msg->spi->dev,
+			"DMA transaction timed out\n");
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+static inline bool dw_spi_dma_tx_busy(struct dw_spi *dws)
+{
+	return !(dw_readl(dws, DW_SPI_SR) & DW_SPI_SR_TF_EMPT);
+}
+
+static int dw_spi_dma_wait_tx_done(struct dw_spi *dws,
+				   struct spi_transfer *xfer)
+{
+	int retry = DW_SPI_WAIT_RETRIES;
+	struct spi_delay delay;
+	u32 nents;
+
+	nents = dw_readl(dws, DW_SPI_TXFLR);
+	delay.unit = SPI_DELAY_UNIT_SCK;
+	delay.value = nents * dws->n_bytes * BITS_PER_BYTE;
+
+	while (dw_spi_dma_tx_busy(dws) && retry--)
+		spi_delay_exec(&delay, xfer);
+
+	if (retry < 0) {
+		dev_err(&dws->master->dev, "Tx hanged up\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+
+/*
+ * dws->dma_chan_busy is set before the dma transfer starts, callback for tx
+ * channel will clear a corresponding bit.
+ */
+static void dw_spi_dma_tx_done(void *arg)
+{
+	struct dw_spi *dws = arg;
+
+	clear_bit(DW_SPI_TX_BUSY, &dws->dma_chan_busy);
+	if (test_bit(DW_SPI_RX_BUSY, &dws->dma_chan_busy))
+		return;
+
+	complete(&dws->dma_completion);
+}
+
+static int dw_spi_dma_config_tx(struct dw_spi *dws)
+{
+	struct dma_slave_config txconf;
+
+	memset(&txconf, 0, sizeof(txconf));
+	txconf.direction = DMA_MEM_TO_DEV;
+	txconf.dst_addr = dws->dma_addr;
+	txconf.dst_maxburst = dws->txburst;
+	txconf.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+	txconf.dst_addr_width = dw_spi_dma_convert_width(dws->n_bytes);
+	txconf.device_fc = false;
+
+	return dmaengine_slave_config(dws->txchan, &txconf);
+}
+
+static int dw_spi_dma_submit_tx(struct dw_spi *dws, struct scatterlist *sgl,
+				unsigned int nents)
+{
+	struct dma_async_tx_descriptor *txdesc;
+	dma_cookie_t cookie;
+	int ret;
+
+	txdesc = dmaengine_prep_slave_sg(dws->txchan, sgl, nents,
+					 DMA_MEM_TO_DEV,
+					 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+	if (!txdesc)
+		return -ENOMEM;
+
+	txdesc->callback = dw_spi_dma_tx_done;
+	txdesc->callback_param = dws;
+
+	cookie = dmaengine_submit(txdesc);
+	ret = dma_submit_error(cookie);
+	if (ret) {
+		dmaengine_terminate_sync(dws->txchan);
+		return ret;
+	}
+
+	set_bit(DW_SPI_TX_BUSY, &dws->dma_chan_busy);
+
+	return 0;
+}
+
+static inline bool dw_spi_dma_rx_busy(struct dw_spi *dws)
+{
+	return !!(dw_readl(dws, DW_SPI_SR) & DW_SPI_SR_RF_NOT_EMPT);
+}
+
+static int dw_spi_dma_wait_rx_done(struct dw_spi *dws)
+{
+	int retry = DW_SPI_WAIT_RETRIES;
+	struct spi_delay delay;
+	unsigned long ns, us;
+	u32 nents;
+
+	/*
+	 * It's unlikely that DMA engine is still doing the data fetching, but
+	 * if it's let's give it some reasonable time. The timeout calculation
+	 * is based on the synchronous APB/SSI reference clock rate, on a
+	 * number of data entries left in the Rx FIFO, times a number of clock
+	 * periods normally needed for a single APB read/write transaction
+	 * without PREADY signal utilized (which is true for the DW APB SSI
+	 * controller).
+	 */
+	nents = dw_readl(dws, DW_SPI_RXFLR);
+	ns = 4U * NSEC_PER_SEC / dws->max_freq * nents;
+	if (ns <= NSEC_PER_USEC) {
+		delay.unit = SPI_DELAY_UNIT_NSECS;
+		delay.value = ns;
+	} else {
+		us = DIV_ROUND_UP(ns, NSEC_PER_USEC);
+		delay.unit = SPI_DELAY_UNIT_USECS;
+		delay.value = clamp_val(us, 0, USHRT_MAX);
+	}
+
+	while (dw_spi_dma_rx_busy(dws) && retry--)
+		spi_delay_exec(&delay, NULL);
+
+	if (retry < 0) {
+		dev_err(&dws->master->dev, "Rx hanged up\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+
+/*
+ * dws->dma_chan_busy is set before the dma transfer starts, callback for rx
+ * channel will clear a corresponding bit.
+ */
+static void dw_spi_dma_rx_done(void *arg)
+{
+	struct dw_spi *dws = arg;
+
+	clear_bit(DW_SPI_RX_BUSY, &dws->dma_chan_busy);
+	if (test_bit(DW_SPI_TX_BUSY, &dws->dma_chan_busy))
+		return;
+
+	complete(&dws->dma_completion);
+}
+
+static int dw_spi_dma_config_rx(struct dw_spi *dws)
+{
+	struct dma_slave_config rxconf;
+
+	memset(&rxconf, 0, sizeof(rxconf));
+	rxconf.direction = DMA_DEV_TO_MEM;
+	rxconf.src_addr = dws->dma_addr;
+	rxconf.src_maxburst = dws->rxburst;
+	rxconf.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+	rxconf.src_addr_width = dw_spi_dma_convert_width(dws->n_bytes);
+	rxconf.device_fc = false;
+
+	return dmaengine_slave_config(dws->rxchan, &rxconf);
+}
+
+static int dw_spi_dma_submit_rx(struct dw_spi *dws, struct scatterlist *sgl,
+				unsigned int nents)
+{
+	struct dma_async_tx_descriptor *rxdesc;
+	dma_cookie_t cookie;
+	int ret;
+
+	rxdesc = dmaengine_prep_slave_sg(dws->rxchan, sgl, nents,
+					 DMA_DEV_TO_MEM,
+					 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+	if (!rxdesc)
+		return -ENOMEM;
+
+	rxdesc->callback = dw_spi_dma_rx_done;
+	rxdesc->callback_param = dws;
+
+	cookie = dmaengine_submit(rxdesc);
+	ret = dma_submit_error(cookie);
+	if (ret) {
+		dmaengine_terminate_sync(dws->rxchan);
+		return ret;
+	}
+
+	set_bit(DW_SPI_RX_BUSY, &dws->dma_chan_busy);
+
+	return 0;
+}
+
+static int dw_spi_dma_setup(struct dw_spi *dws, struct spi_transfer *xfer)
+{
+	u16 imr, dma_ctrl;
+	int ret;
+
+	if (!xfer->tx_buf)
+		return -EINVAL;
+
+	/* Setup DMA channels */
+	ret = dw_spi_dma_config_tx(dws);
+	if (ret)
+		return ret;
+
+	if (xfer->rx_buf) {
+		ret = dw_spi_dma_config_rx(dws);
+		if (ret)
+			return ret;
+	}
+
+	/* Set the DMA handshaking interface */
+	dma_ctrl = DW_SPI_DMACR_TDMAE;
+	if (xfer->rx_buf)
+		dma_ctrl |= DW_SPI_DMACR_RDMAE;
+	dw_writel(dws, DW_SPI_DMACR, dma_ctrl);
+
+	/* Set the interrupt mask */
+	imr = DW_SPI_INT_TXOI;
+	if (xfer->rx_buf)
+		imr |= DW_SPI_INT_RXUI | DW_SPI_INT_RXOI;
+	dw_spi_umask_intr(dws, imr);
+
+	reinit_completion(&dws->dma_completion);
+
+	dws->transfer_handler = dw_spi_dma_transfer_handler;
+
+	return 0;
+}
+
+static int dw_spi_dma_transfer_all(struct dw_spi *dws,
+				   struct spi_transfer *xfer)
+{
+	int ret;
+
+	/* Submit the DMA Tx transfer */
+	ret = dw_spi_dma_submit_tx(dws, xfer->tx_sg.sgl, xfer->tx_sg.nents);
+	if (ret)
+		goto err_clear_dmac;
+
+	/* Submit the DMA Rx transfer if required */
+	if (xfer->rx_buf) {
+		ret = dw_spi_dma_submit_rx(dws, xfer->rx_sg.sgl,
+					   xfer->rx_sg.nents);
+		if (ret)
+			goto err_clear_dmac;
+
+		/* rx must be started before tx due to spi instinct */
+		dma_async_issue_pending(dws->rxchan);
+	}
+
+	dma_async_issue_pending(dws->txchan);
+
+	ret = dw_spi_dma_wait(dws, xfer->len, xfer->effective_speed_hz);
+
+err_clear_dmac:
+	dw_writel(dws, DW_SPI_DMACR, 0);
+
+	return ret;
+}
+
+/*
+ * In case if at least one of the requested DMA channels doesn't support the
+ * hardware accelerated SG list entries traverse, the DMA driver will most
+ * likely work that around by performing the IRQ-based SG list entries
+ * resubmission. That might and will cause a problem if the DMA Tx channel is
+ * recharged and re-executed before the Rx DMA channel. Due to
+ * non-deterministic IRQ-handler execution latency the DMA Tx channel will
+ * start pushing data to the SPI bus before the Rx DMA channel is even
+ * reinitialized with the next inbound SG list entry. By doing so the DMA Tx
+ * channel will implicitly start filling the DW APB SSI Rx FIFO up, which while
+ * the DMA Rx channel being recharged and re-executed will eventually be
+ * overflown.
+ *
+ * In order to solve the problem we have to feed the DMA engine with SG list
+ * entries one-by-one. It shall keep the DW APB SSI Tx and Rx FIFOs
+ * synchronized and prevent the Rx FIFO overflow. Since in general the tx_sg
+ * and rx_sg lists may have different number of entries of different lengths
+ * (though total length should match) let's virtually split the SG-lists to the
+ * set of DMA transfers, which length is a minimum of the ordered SG-entries
+ * lengths. An ASCII-sketch of the implemented algo is following:
+ *                  xfer->len
+ *                |___________|
+ * tx_sg list:    |___|____|__|
+ * rx_sg list:    |_|____|____|
+ * DMA transfers: |_|_|__|_|__|
+ *
+ * Note in order to have this workaround solving the denoted problem the DMA
+ * engine driver should properly initialize the max_sg_burst capability and set
+ * the DMA device max segment size parameter with maximum data block size the
+ * DMA engine supports.
+ */
+
+static int dw_spi_dma_transfer_one(struct dw_spi *dws,
+				   struct spi_transfer *xfer)
+{
+	struct scatterlist *tx_sg = NULL, *rx_sg = NULL, tx_tmp, rx_tmp;
+	unsigned int tx_len = 0, rx_len = 0;
+	unsigned int base, len;
+	int ret;
+
+	sg_init_table(&tx_tmp, 1);
+	sg_init_table(&rx_tmp, 1);
+
+	for (base = 0, len = 0; base < xfer->len; base += len) {
+		/* Fetch next Tx DMA data chunk */
+		if (!tx_len) {
+			tx_sg = !tx_sg ? &xfer->tx_sg.sgl[0] : sg_next(tx_sg);
+			sg_dma_address(&tx_tmp) = sg_dma_address(tx_sg);
+			tx_len = sg_dma_len(tx_sg);
+		}
+
+		/* Fetch next Rx DMA data chunk */
+		if (!rx_len) {
+			rx_sg = !rx_sg ? &xfer->rx_sg.sgl[0] : sg_next(rx_sg);
+			sg_dma_address(&rx_tmp) = sg_dma_address(rx_sg);
+			rx_len = sg_dma_len(rx_sg);
+		}
+
+		len = min(tx_len, rx_len);
+
+		sg_dma_len(&tx_tmp) = len;
+		sg_dma_len(&rx_tmp) = len;
+
+		/* Submit DMA Tx transfer */
+		ret = dw_spi_dma_submit_tx(dws, &tx_tmp, 1);
+		if (ret)
+			break;
+
+		/* Submit DMA Rx transfer */
+		ret = dw_spi_dma_submit_rx(dws, &rx_tmp, 1);
+		if (ret)
+			break;
+
+		/* Rx must be started before Tx due to SPI instinct */
+		dma_async_issue_pending(dws->rxchan);
+
+		dma_async_issue_pending(dws->txchan);
+
+		/*
+		 * Here we only need to wait for the DMA transfer to be
+		 * finished since SPI controller is kept enabled during the
+		 * procedure this loop implements and there is no risk to lose
+		 * data left in the Tx/Rx FIFOs.
+		 */
+		ret = dw_spi_dma_wait(dws, len, xfer->effective_speed_hz);
+		if (ret)
+			break;
+
+		reinit_completion(&dws->dma_completion);
+
+		sg_dma_address(&tx_tmp) += len;
+		sg_dma_address(&rx_tmp) += len;
+		tx_len -= len;
+		rx_len -= len;
+	}
+
+	dw_writel(dws, DW_SPI_DMACR, 0);
+
+	return ret;
+}
+
+static int dw_spi_dma_transfer(struct dw_spi *dws, struct spi_transfer *xfer)
+{
+	unsigned int nents;
+	int ret;
+
+	nents = max(xfer->tx_sg.nents, xfer->rx_sg.nents);
+
+	/*
+	 * Execute normal DMA-based transfer (which submits the Rx and Tx SG
+	 * lists directly to the DMA engine at once) if either full hardware
+	 * accelerated SG list traverse is supported by both channels, or the
+	 * Tx-only SPI transfer is requested, or the DMA engine is capable to
+	 * handle both SG lists on hardware accelerated basis.
+	 */
+	if (!dws->dma_sg_burst || !xfer->rx_buf || nents <= dws->dma_sg_burst)
+		ret = dw_spi_dma_transfer_all(dws, xfer);
+	else
+		ret = dw_spi_dma_transfer_one(dws, xfer);
+	if (ret)
+		return ret;
+
+	if (dws->master->cur_msg->status == -EINPROGRESS) {
+		ret = dw_spi_dma_wait_tx_done(dws, xfer);
+		if (ret)
+			return ret;
+	}
+
+	if (xfer->rx_buf && dws->master->cur_msg->status == -EINPROGRESS)
+		ret = dw_spi_dma_wait_rx_done(dws);
+
+	return ret;
+}
+
+static void dw_spi_dma_stop(struct dw_spi *dws)
+{
+	if (test_bit(DW_SPI_TX_BUSY, &dws->dma_chan_busy)) {
+		dmaengine_terminate_sync(dws->txchan);
+		clear_bit(DW_SPI_TX_BUSY, &dws->dma_chan_busy);
+	}
+	if (test_bit(DW_SPI_RX_BUSY, &dws->dma_chan_busy)) {
+		dmaengine_terminate_sync(dws->rxchan);
+		clear_bit(DW_SPI_RX_BUSY, &dws->dma_chan_busy);
+	}
+}
+
+static const struct dw_spi_dma_ops dw_spi_dma_mfld_ops = {
+	.dma_init	= dw_spi_dma_init_mfld,
+	.dma_exit	= dw_spi_dma_exit,
+	.dma_setup	= dw_spi_dma_setup,
+	.can_dma	= dw_spi_can_dma,
+	.dma_transfer	= dw_spi_dma_transfer,
+	.dma_stop	= dw_spi_dma_stop,
+};
+
+void dw_spi_dma_setup_mfld(struct dw_spi *dws)
+{
+	dws->dma_ops = &dw_spi_dma_mfld_ops;
+}
+EXPORT_SYMBOL_NS_GPL(dw_spi_dma_setup_mfld, SPI_DW_CORE);
+
+static const struct dw_spi_dma_ops dw_spi_dma_generic_ops = {
+	.dma_init	= dw_spi_dma_init_generic,
+	.dma_exit	= dw_spi_dma_exit,
+	.dma_setup	= dw_spi_dma_setup,
+	.can_dma	= dw_spi_can_dma,
+	.dma_transfer	= dw_spi_dma_transfer,
+	.dma_stop	= dw_spi_dma_stop,
+};
+
+void dw_spi_dma_setup_generic(struct dw_spi *dws)
+{
+	dws->dma_ops = &dw_spi_dma_generic_ops;
+}
+EXPORT_SYMBOL_NS_GPL(dw_spi_dma_setup_generic, SPI_DW_CORE);