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, 695 insertions, 0 deletions

diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c
new file mode 100644
index 000000000..fc90293af
--- /dev/null
+++ b/drivers/i2c/algos/i2c-algo-bit.c
@@ -0,0 +1,695 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * i2c-algo-bit.c: i2c driver algorithms for bit-shift adapters
+ *
+ *   Copyright (C) 1995-2000 Simon G. Vogl
+ *
+ * With some changes from Frodo Looijaard <frodol@dds.nl>, Kyösti Mälkki
+ * <kmalkki@cc.hut.fi> and Jean Delvare <jdelvare@suse.de>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/i2c.h>
+#include <linux/i2c-algo-bit.h>
+
+
+/* ----- global defines ----------------------------------------------- */
+
+#ifdef DEBUG
+#define bit_dbg(level, dev, format, args...) \
+	do { \
+		if (i2c_debug >= level) \
+			dev_dbg(dev, format, ##args); \
+	} while (0)
+#else
+#define bit_dbg(level, dev, format, args...) \
+	do {} while (0)
+#endif /* DEBUG */
+
+/* ----- global variables ---------------------------------------------	*/
+
+static int bit_test;	/* see if the line-setting functions work	*/
+module_param(bit_test, int, S_IRUGO);
+MODULE_PARM_DESC(bit_test, "lines testing - 0 off; 1 report; 2 fail if stuck");
+
+#ifdef DEBUG
+static int i2c_debug = 1;
+module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(i2c_debug,
+		 "debug level - 0 off; 1 normal; 2 verbose; 3 very verbose");
+#endif
+
+/* --- setting states on the bus with the right timing: ---------------	*/
+
+#define setsda(adap, val)	adap->setsda(adap->data, val)
+#define setscl(adap, val)	adap->setscl(adap->data, val)
+#define getsda(adap)		adap->getsda(adap->data)
+#define getscl(adap)		adap->getscl(adap->data)
+
+static inline void sdalo(struct i2c_algo_bit_data *adap)
+{
+	setsda(adap, 0);
+	udelay((adap->udelay + 1) / 2);
+}
+
+static inline void sdahi(struct i2c_algo_bit_data *adap)
+{
+	setsda(adap, 1);
+	udelay((adap->udelay + 1) / 2);
+}
+
+static inline void scllo(struct i2c_algo_bit_data *adap)
+{
+	setscl(adap, 0);
+	udelay(adap->udelay / 2);
+}
+
+/*
+ * Raise scl line, and do checking for delays. This is necessary for slower
+ * devices.
+ */
+static int sclhi(struct i2c_algo_bit_data *adap)
+{
+	unsigned long start;
+
+	setscl(adap, 1);
+
+	/* Not all adapters have scl sense line... */
+	if (!adap->getscl)
+		goto done;
+
+	start = jiffies;
+	while (!getscl(adap)) {
+		/* This hw knows how to read the clock line, so we wait
+		 * until it actually gets high.  This is safer as some
+		 * chips may hold it low ("clock stretching") while they
+		 * are processing data internally.
+		 */
+		if (time_after(jiffies, start + adap->timeout)) {
+			/* Test one last time, as we may have been preempted
+			 * between last check and timeout test.
+			 */
+			if (getscl(adap))
+				break;
+			return -ETIMEDOUT;
+		}
+		cpu_relax();
+	}
+#ifdef DEBUG
+	if (jiffies != start && i2c_debug >= 3)
+		pr_debug("i2c-algo-bit: needed %ld jiffies for SCL to go high\n",
+			 jiffies - start);
+#endif
+
+done:
+	udelay(adap->udelay);
+	return 0;
+}
+
+
+/* --- other auxiliary functions --------------------------------------	*/
+static void i2c_start(struct i2c_algo_bit_data *adap)
+{
+	/* assert: scl, sda are high */
+	setsda(adap, 0);
+	udelay(adap->udelay);
+	scllo(adap);
+}
+
+static void i2c_repstart(struct i2c_algo_bit_data *adap)
+{
+	/* assert: scl is low */
+	sdahi(adap);
+	sclhi(adap);
+	setsda(adap, 0);
+	udelay(adap->udelay);
+	scllo(adap);
+}
+
+
+static void i2c_stop(struct i2c_algo_bit_data *adap)
+{
+	/* assert: scl is low */
+	sdalo(adap);
+	sclhi(adap);
+	setsda(adap, 1);
+	udelay(adap->udelay);
+}
+
+
+
+/* send a byte without start cond., look for arbitration,
+   check ackn. from slave */
+/* returns:
+ * 1 if the device acknowledged
+ * 0 if the device did not ack
+ * -ETIMEDOUT if an error occurred (while raising the scl line)
+ */
+static int i2c_outb(struct i2c_adapter *i2c_adap, unsigned char c)
+{
+	int i;
+	int sb;
+	int ack;
+	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
+
+	/* assert: scl is low */
+	for (i = 7; i >= 0; i--) {
+		sb = (c >> i) & 1;
+		setsda(adap, sb);
+		udelay((adap->udelay + 1) / 2);
+		if (sclhi(adap) < 0) { /* timed out */
+			bit_dbg(1, &i2c_adap->dev,
+				"i2c_outb: 0x%02x, timeout at bit #%d\n",
+				(int)c, i);
+			return -ETIMEDOUT;
+		}
+		/* FIXME do arbitration here:
+		 * if (sb && !getsda(adap)) -> ouch! Get out of here.
+		 *
+		 * Report a unique code, so higher level code can retry
+		 * the whole (combined) message and *NOT* issue STOP.
+		 */
+		scllo(adap);
+	}
+	sdahi(adap);
+	if (sclhi(adap) < 0) { /* timeout */
+		bit_dbg(1, &i2c_adap->dev,
+			"i2c_outb: 0x%02x, timeout at ack\n", (int)c);
+		return -ETIMEDOUT;
+	}
+
+	/* read ack: SDA should be pulled down by slave, or it may
+	 * NAK (usually to report problems with the data we wrote).
+	 */
+	ack = !getsda(adap);    /* ack: sda is pulled low -> success */
+	bit_dbg(2, &i2c_adap->dev, "i2c_outb: 0x%02x %s\n", (int)c,
+		ack ? "A" : "NA");
+
+	scllo(adap);
+	return ack;
+	/* assert: scl is low (sda undef) */
+}
+
+
+static int i2c_inb(struct i2c_adapter *i2c_adap)
+{
+	/* read byte via i2c port, without start/stop sequence	*/
+	/* acknowledge is sent in i2c_read.			*/
+	int i;
+	unsigned char indata = 0;
+	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
+
+	/* assert: scl is low */
+	sdahi(adap);
+	for (i = 0; i < 8; i++) {
+		if (sclhi(adap) < 0) { /* timeout */
+			bit_dbg(1, &i2c_adap->dev,
+				"i2c_inb: timeout at bit #%d\n",
+				7 - i);
+			return -ETIMEDOUT;
+		}
+		indata *= 2;
+		if (getsda(adap))
+			indata |= 0x01;
+		setscl(adap, 0);
+		udelay(i == 7 ? adap->udelay / 2 : adap->udelay);
+	}
+	/* assert: scl is low */
+	return indata;
+}
+
+/*
+ * Sanity check for the adapter hardware - check the reaction of
+ * the bus lines only if it seems to be idle.
+ */
+static int test_bus(struct i2c_adapter *i2c_adap)
+{
+	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
+	const char *name = i2c_adap->name;
+	int scl, sda, ret;
+
+	if (adap->pre_xfer) {
+		ret = adap->pre_xfer(i2c_adap);
+		if (ret < 0)
+			return -ENODEV;
+	}
+
+	if (adap->getscl == NULL)
+		pr_info("%s: Testing SDA only, SCL is not readable\n", name);
+
+	sda = getsda(adap);
+	scl = (adap->getscl == NULL) ? 1 : getscl(adap);
+	if (!scl || !sda) {
+		printk(KERN_WARNING
+		       "%s: bus seems to be busy (scl=%d, sda=%d)\n",
+		       name, scl, sda);
+		goto bailout;
+	}
+
+	sdalo(adap);
+	sda = getsda(adap);
+	scl = (adap->getscl == NULL) ? 1 : getscl(adap);
+	if (sda) {
+		printk(KERN_WARNING "%s: SDA stuck high!\n", name);
+		goto bailout;
+	}
+	if (!scl) {
+		printk(KERN_WARNING
+		       "%s: SCL unexpected low while pulling SDA low!\n",
+		       name);
+		goto bailout;
+	}
+
+	sdahi(adap);
+	sda = getsda(adap);
+	scl = (adap->getscl == NULL) ? 1 : getscl(adap);
+	if (!sda) {
+		printk(KERN_WARNING "%s: SDA stuck low!\n", name);
+		goto bailout;
+	}
+	if (!scl) {
+		printk(KERN_WARNING
+		       "%s: SCL unexpected low while pulling SDA high!\n",
+		       name);
+		goto bailout;
+	}
+
+	scllo(adap);
+	sda = getsda(adap);
+	scl = (adap->getscl == NULL) ? 0 : getscl(adap);
+	if (scl) {
+		printk(KERN_WARNING "%s: SCL stuck high!\n", name);
+		goto bailout;
+	}
+	if (!sda) {
+		printk(KERN_WARNING
+		       "%s: SDA unexpected low while pulling SCL low!\n",
+		       name);
+		goto bailout;
+	}
+
+	sclhi(adap);
+	sda = getsda(adap);
+	scl = (adap->getscl == NULL) ? 1 : getscl(adap);
+	if (!scl) {
+		printk(KERN_WARNING "%s: SCL stuck low!\n", name);
+		goto bailout;
+	}
+	if (!sda) {
+		printk(KERN_WARNING
+		       "%s: SDA unexpected low while pulling SCL high!\n",
+		       name);
+		goto bailout;
+	}
+
+	if (adap->post_xfer)
+		adap->post_xfer(i2c_adap);
+
+	pr_info("%s: Test OK\n", name);
+	return 0;
+bailout:
+	sdahi(adap);
+	sclhi(adap);
+
+	if (adap->post_xfer)
+		adap->post_xfer(i2c_adap);
+
+	return -ENODEV;
+}
+
+/* ----- Utility functions
+ */
+
+/* try_address tries to contact a chip for a number of
+ * times before it gives up.
+ * return values:
+ * 1 chip answered
+ * 0 chip did not answer
+ * -x transmission error
+ */
+static int try_address(struct i2c_adapter *i2c_adap,
+		       unsigned char addr, int retries)
+{
+	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
+	int i, ret = 0;
+
+	for (i = 0; i <= retries; i++) {
+		ret = i2c_outb(i2c_adap, addr);
+		if (ret == 1 || i == retries)
+			break;
+		bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n");
+		i2c_stop(adap);
+		udelay(adap->udelay);
+		yield();
+		bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
+		i2c_start(adap);
+	}
+	if (i && ret)
+		bit_dbg(1, &i2c_adap->dev,
+			"Used %d tries to %s client at 0x%02x: %s\n", i + 1,
+			addr & 1 ? "read from" : "write to", addr >> 1,
+			ret == 1 ? "success" : "failed, timeout?");
+	return ret;
+}
+
+static int sendbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
+{
+	const unsigned char *temp = msg->buf;
+	int count = msg->len;
+	unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
+	int retval;
+	int wrcount = 0;
+
+	while (count > 0) {
+		retval = i2c_outb(i2c_adap, *temp);
+
+		/* OK/ACK; or ignored NAK */
+		if ((retval > 0) || (nak_ok && (retval == 0))) {
+			count--;
+			temp++;
+			wrcount++;
+
+		/* A slave NAKing the master means the slave didn't like
+		 * something about the data it saw.  For example, maybe
+		 * the SMBus PEC was wrong.
+		 */
+		} else if (retval == 0) {
+			dev_err(&i2c_adap->dev, "sendbytes: NAK bailout.\n");
+			return -EIO;
+
+		/* Timeout; or (someday) lost arbitration
+		 *
+		 * FIXME Lost ARB implies retrying the transaction from
+		 * the first message, after the "winning" master issues
+		 * its STOP.  As a rule, upper layer code has no reason
+		 * to know or care about this ... it is *NOT* an error.
+		 */
+		} else {
+			dev_err(&i2c_adap->dev, "sendbytes: error %d\n",
+					retval);
+			return retval;
+		}
+	}
+	return wrcount;
+}
+
+static int acknak(struct i2c_adapter *i2c_adap, int is_ack)
+{
+	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
+
+	/* assert: sda is high */
+	if (is_ack)		/* send ack */
+		setsda(adap, 0);
+	udelay((adap->udelay + 1) / 2);
+	if (sclhi(adap) < 0) {	/* timeout */
+		dev_err(&i2c_adap->dev, "readbytes: ack/nak timeout\n");
+		return -ETIMEDOUT;
+	}
+	scllo(adap);
+	return 0;
+}
+
+static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
+{
+	int inval;
+	int rdcount = 0;	/* counts bytes read */
+	unsigned char *temp = msg->buf;
+	int count = msg->len;
+	const unsigned flags = msg->flags;
+
+	while (count > 0) {
+		inval = i2c_inb(i2c_adap);
+		if (inval >= 0) {
+			*temp = inval;
+			rdcount++;
+		} else {   /* read timed out */
+			break;
+		}
+
+		temp++;
+		count--;
+
+		/* Some SMBus transactions require that we receive the
+		   transaction length as the first read byte. */
+		if (rdcount == 1 && (flags & I2C_M_RECV_LEN)) {
+			if (inval <= 0 || inval > I2C_SMBUS_BLOCK_MAX) {
+				if (!(flags & I2C_M_NO_RD_ACK))
+					acknak(i2c_adap, 0);
+				dev_err(&i2c_adap->dev,
+					"readbytes: invalid block length (%d)\n",
+					inval);
+				return -EPROTO;
+			}
+			/* The original count value accounts for the extra
+			   bytes, that is, either 1 for a regular transaction,
+			   or 2 for a PEC transaction. */
+			count += inval;
+			msg->len += inval;
+		}
+
+		bit_dbg(2, &i2c_adap->dev, "readbytes: 0x%02x %s\n",
+			inval,
+			(flags & I2C_M_NO_RD_ACK)
+				? "(no ack/nak)"
+				: (count ? "A" : "NA"));
+
+		if (!(flags & I2C_M_NO_RD_ACK)) {
+			inval = acknak(i2c_adap, count);
+			if (inval < 0)
+				return inval;
+		}
+	}
+	return rdcount;
+}
+
+/* doAddress initiates the transfer by generating the start condition (in
+ * try_address) and transmits the address in the necessary format to handle
+ * reads, writes as well as 10bit-addresses.
+ * returns:
+ *  0 everything went okay, the chip ack'ed, or IGNORE_NAK flag was set
+ * -x an error occurred (like: -ENXIO if the device did not answer, or
+ *	-ETIMEDOUT, for example if the lines are stuck...)
+ */
+static int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
+{
+	unsigned short flags = msg->flags;
+	unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
+	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
+
+	unsigned char addr;
+	int ret, retries;
+
+	retries = nak_ok ? 0 : i2c_adap->retries;
+
+	if (flags & I2C_M_TEN) {
+		/* a ten bit address */
+		addr = 0xf0 | ((msg->addr >> 7) & 0x06);
+		bit_dbg(2, &i2c_adap->dev, "addr0: %d\n", addr);
+		/* try extended address code...*/
+		ret = try_address(i2c_adap, addr, retries);
+		if ((ret != 1) && !nak_ok)  {
+			dev_err(&i2c_adap->dev,
+				"died at extended address code\n");
+			return -ENXIO;
+		}
+		/* the remaining 8 bit address */
+		ret = i2c_outb(i2c_adap, msg->addr & 0xff);
+		if ((ret != 1) && !nak_ok) {
+			/* the chip did not ack / xmission error occurred */
+			dev_err(&i2c_adap->dev, "died at 2nd address code\n");
+			return -ENXIO;
+		}
+		if (flags & I2C_M_RD) {
+			bit_dbg(3, &i2c_adap->dev,
+				"emitting repeated start condition\n");
+			i2c_repstart(adap);
+			/* okay, now switch into reading mode */
+			addr |= 0x01;
+			ret = try_address(i2c_adap, addr, retries);
+			if ((ret != 1) && !nak_ok) {
+				dev_err(&i2c_adap->dev,
+					"died at repeated address code\n");
+				return -EIO;
+			}
+		}
+	} else {		/* normal 7bit address	*/
+		addr = i2c_8bit_addr_from_msg(msg);
+		if (flags & I2C_M_REV_DIR_ADDR)
+			addr ^= 1;
+		ret = try_address(i2c_adap, addr, retries);
+		if ((ret != 1) && !nak_ok)
+			return -ENXIO;
+	}
+
+	return 0;
+}
+
+static int bit_xfer(struct i2c_adapter *i2c_adap,
+		    struct i2c_msg msgs[], int num)
+{
+	struct i2c_msg *pmsg;
+	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
+	int i, ret;
+	unsigned short nak_ok;
+
+	if (adap->pre_xfer) {
+		ret = adap->pre_xfer(i2c_adap);
+		if (ret < 0)
+			return ret;
+	}
+
+	bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
+	i2c_start(adap);
+	for (i = 0; i < num; i++) {
+		pmsg = &msgs[i];
+		nak_ok = pmsg->flags & I2C_M_IGNORE_NAK;
+		if (!(pmsg->flags & I2C_M_NOSTART)) {
+			if (i) {
+				if (msgs[i - 1].flags & I2C_M_STOP) {
+					bit_dbg(3, &i2c_adap->dev,
+						"emitting enforced stop/start condition\n");
+					i2c_stop(adap);
+					i2c_start(adap);
+				} else {
+					bit_dbg(3, &i2c_adap->dev,
+						"emitting repeated start condition\n");
+					i2c_repstart(adap);
+				}
+			}
+			ret = bit_doAddress(i2c_adap, pmsg);
+			if ((ret != 0) && !nak_ok) {
+				bit_dbg(1, &i2c_adap->dev,
+					"NAK from device addr 0x%02x msg #%d\n",
+					msgs[i].addr, i);
+				goto bailout;
+			}
+		}
+		if (pmsg->flags & I2C_M_RD) {
+			/* read bytes into buffer*/
+			ret = readbytes(i2c_adap, pmsg);
+			if (ret >= 1)
+				bit_dbg(2, &i2c_adap->dev, "read %d byte%s\n",
+					ret, ret == 1 ? "" : "s");
+			if (ret < pmsg->len) {
+				if (ret >= 0)
+					ret = -EIO;
+				goto bailout;
+			}
+		} else {
+			/* write bytes from buffer */
+			ret = sendbytes(i2c_adap, pmsg);
+			if (ret >= 1)
+				bit_dbg(2, &i2c_adap->dev, "wrote %d byte%s\n",
+					ret, ret == 1 ? "" : "s");
+			if (ret < pmsg->len) {
+				if (ret >= 0)
+					ret = -EIO;
+				goto bailout;
+			}
+		}
+	}
+	ret = i;
+
+bailout:
+	bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n");
+	i2c_stop(adap);
+
+	if (adap->post_xfer)
+		adap->post_xfer(i2c_adap);
+	return ret;
+}
+
+/*
+ * We print a warning when we are not flagged to support atomic transfers but
+ * will try anyhow. That's what the I2C core would do as well. Sadly, we can't
+ * modify the algorithm struct at probe time because this struct is exported
+ * 'const'.
+ */
+static int bit_xfer_atomic(struct i2c_adapter *i2c_adap, struct i2c_msg msgs[],
+			   int num)
+{
+	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
+
+	if (!adap->can_do_atomic)
+		dev_warn(&i2c_adap->dev, "not flagged for atomic transfers\n");
+
+	return bit_xfer(i2c_adap, msgs, num);
+}
+
+static u32 bit_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_NOSTART | I2C_FUNC_SMBUS_EMUL_ALL |
+	       I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;
+}
+
+
+/* -----exported algorithm data: -------------------------------------	*/
+
+const struct i2c_algorithm i2c_bit_algo = {
+	.master_xfer = bit_xfer,
+	.master_xfer_atomic = bit_xfer_atomic,
+	.functionality = bit_func,
+};
+EXPORT_SYMBOL(i2c_bit_algo);
+
+static const struct i2c_adapter_quirks i2c_bit_quirk_no_clk_stretch = {
+	.flags = I2C_AQ_NO_CLK_STRETCH,
+};
+
+/*
+ * registering functions to load algorithms at runtime
+ */
+static int __i2c_bit_add_bus(struct i2c_adapter *adap,
+			     int (*add_adapter)(struct i2c_adapter *))
+{
+	struct i2c_algo_bit_data *bit_adap = adap->algo_data;
+	int ret;
+
+	if (bit_test) {
+		ret = test_bus(adap);
+		if (bit_test >= 2 && ret < 0)
+			return -ENODEV;
+	}
+
+	/* register new adapter to i2c module... */
+	adap->algo = &i2c_bit_algo;
+	adap->retries = 3;
+	if (bit_adap->getscl == NULL)
+		adap->quirks = &i2c_bit_quirk_no_clk_stretch;
+
+	/*
+	 * We tried forcing SCL/SDA to an initial state here. But that caused a
+	 * regression, sadly. Check Bugzilla #200045 for details.
+	 */
+
+	ret = add_adapter(adap);
+	if (ret < 0)
+		return ret;
+
+	/* Complain if SCL can't be read */
+	if (bit_adap->getscl == NULL) {
+		dev_warn(&adap->dev, "Not I2C compliant: can't read SCL\n");
+		dev_warn(&adap->dev, "Bus may be unreliable\n");
+	}
+	return 0;
+}
+
+int i2c_bit_add_bus(struct i2c_adapter *adap)
+{
+	return __i2c_bit_add_bus(adap, i2c_add_adapter);
+}
+EXPORT_SYMBOL(i2c_bit_add_bus);
+
+int i2c_bit_add_numbered_bus(struct i2c_adapter *adap)
+{
+	return __i2c_bit_add_bus(adap, i2c_add_numbered_adapter);
+}
+EXPORT_SYMBOL(i2c_bit_add_numbered_bus);
+
+MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
+MODULE_DESCRIPTION("I2C-Bus bit-banging algorithm");
+MODULE_LICENSE("GPL");