diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 9da0bc5..f9502db 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1,19 +1,8 @@
-/*
- * SPI init/core code
- *
- * Copyright (C) 2005 David Brownell
- * Copyright (C) 2008 Secret Lab Technologies Ltd.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- */
+// SPDX-License-Identifier: GPL-2.0-or-later
+// SPI init/core code
+//
+// Copyright (C) 2005 David Brownell
+// Copyright (C) 2008 Secret Lab Technologies Ltd.
 
 #include <linux/kernel.h>
 #include <linux/device.h>
@@ -30,6 +19,7 @@
 #include <linux/spi/spi.h>
 #include <linux/spi/spi-mem.h>
 #include <linux/of_gpio.h>
+#include <linux/gpio/consumer.h>
 #include <linux/pm_runtime.h>
 #include <linux/pm_domain.h>
 #include <linux/property.h>
@@ -46,6 +36,8 @@
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/spi.h>
+EXPORT_TRACEPOINT_SYMBOL(spi_transfer_start);
+EXPORT_TRACEPOINT_SYMBOL(spi_transfer_stop);
 
 #include "internals.h"
 
@@ -60,6 +52,7 @@
 		spi->controller->cleanup(spi);
 
 	spi_controller_put(spi->controller);
+	kfree(spi->driver_override);
 	kfree(spi);
 }
 
@@ -77,6 +70,51 @@
 }
 static DEVICE_ATTR_RO(modalias);
 
+static ssize_t driver_override_store(struct device *dev,
+				     struct device_attribute *a,
+				     const char *buf, size_t count)
+{
+	struct spi_device *spi = to_spi_device(dev);
+	const char *end = memchr(buf, '\n', count);
+	const size_t len = end ? end - buf : count;
+	const char *driver_override, *old;
+
+	/* We need to keep extra room for a newline when displaying value */
+	if (len >= (PAGE_SIZE - 1))
+		return -EINVAL;
+
+	driver_override = kstrndup(buf, len, GFP_KERNEL);
+	if (!driver_override)
+		return -ENOMEM;
+
+	device_lock(dev);
+	old = spi->driver_override;
+	if (len) {
+		spi->driver_override = driver_override;
+	} else {
+		/* Emptry string, disable driver override */
+		spi->driver_override = NULL;
+		kfree(driver_override);
+	}
+	device_unlock(dev);
+	kfree(old);
+
+	return count;
+}
+
+static ssize_t driver_override_show(struct device *dev,
+				    struct device_attribute *a, char *buf)
+{
+	const struct spi_device *spi = to_spi_device(dev);
+	ssize_t len;
+
+	device_lock(dev);
+	len = snprintf(buf, PAGE_SIZE, "%s\n", spi->driver_override ? : "");
+	device_unlock(dev);
+	return len;
+}
+static DEVICE_ATTR_RW(driver_override);
+
 #define SPI_STATISTICS_ATTRS(field, file)				\
 static ssize_t spi_controller_##field##_show(struct device *dev,	\
 					     struct device_attribute *attr, \
@@ -158,6 +196,7 @@
 
 static struct attribute *spi_dev_attrs[] = {
 	&dev_attr_modalias.attr,
+	&dev_attr_driver_override.attr,
 	NULL,
 };
 
@@ -305,6 +344,10 @@
 	const struct spi_device	*spi = to_spi_device(dev);
 	const struct spi_driver	*sdrv = to_spi_driver(drv);
 
+	/* Check override first, and if set, only use the named driver */
+	if (spi->driver_override)
+		return strcmp(spi->driver_override, drv->name) == 0;
+
 	/* Attempt an OF style match */
 	if (of_driver_match_device(dev, drv))
 		return 1;
@@ -538,7 +581,10 @@
 		goto done;
 	}
 
-	if (ctlr->cs_gpios)
+	/* Descriptors take precedence */
+	if (ctlr->cs_gpiods)
+		spi->cs_gpiod = ctlr->cs_gpiods[spi->chip_select];
+	else if (ctlr->cs_gpios)
 		spi->cs_gpio = ctlr->cs_gpios[spi->chip_select];
 
 	/* Drivers may modify this initial i/o setup, but will
@@ -732,8 +778,21 @@
 	if (spi->mode & SPI_CS_HIGH)
 		enable = !enable;
 
-	if (gpio_is_valid(spi->cs_gpio)) {
-		gpio_set_value(spi->cs_gpio, !enable);
+	if (spi->cs_gpiod || gpio_is_valid(spi->cs_gpio)) {
+		/*
+		 * Honour the SPI_NO_CS flag and invert the enable line, as
+		 * active low is default for SPI. Execution paths that handle
+		 * polarity inversion in gpiolib (such as device tree) will
+		 * enforce active high using the SPI_CS_HIGH resulting in a
+		 * double inversion through the code above.
+		 */
+		if (!(spi->mode & SPI_NO_CS)) {
+			if (spi->cs_gpiod)
+				gpiod_set_value_cansleep(spi->cs_gpiod,
+							 !enable);
+			else
+				gpio_set_value_cansleep(spi->cs_gpio, !enable);
+		}
 		/* Some SPI masters need both GPIO CS & slave_select */
 		if ((spi->controller->flags & SPI_MASTER_GPIO_SS) &&
 		    spi->controller->set_cs)
@@ -982,6 +1041,8 @@
 		if (max_tx || max_rx) {
 			list_for_each_entry(xfer, &msg->transfers,
 					    transfer_list) {
+				if (!xfer->len)
+					continue;
 				if (!xfer->tx_buf)
 					xfer->tx_buf = ctlr->dummy_tx;
 				if (!xfer->rx_buf)
@@ -993,6 +1054,96 @@
 	return __spi_map_msg(ctlr, msg);
 }
 
+static int spi_transfer_wait(struct spi_controller *ctlr,
+			     struct spi_message *msg,
+			     struct spi_transfer *xfer)
+{
+	struct spi_statistics *statm = &ctlr->statistics;
+	struct spi_statistics *stats = &msg->spi->statistics;
+	unsigned long long ms = 1;
+
+	if (spi_controller_is_slave(ctlr)) {
+		if (wait_for_completion_interruptible(&ctlr->xfer_completion)) {
+			dev_dbg(&msg->spi->dev, "SPI transfer interrupted\n");
+			return -EINTR;
+		}
+	} else {
+		ms = 8LL * 1000LL * xfer->len;
+		do_div(ms, xfer->speed_hz);
+		ms += ms + 200; /* some tolerance */
+
+		if (ms > UINT_MAX)
+			ms = UINT_MAX;
+
+		ms = wait_for_completion_timeout(&ctlr->xfer_completion,
+						 msecs_to_jiffies(ms));
+
+		if (ms == 0) {
+			SPI_STATISTICS_INCREMENT_FIELD(statm, timedout);
+			SPI_STATISTICS_INCREMENT_FIELD(stats, timedout);
+			dev_err(&msg->spi->dev,
+				"SPI transfer timed out\n");
+			return -ETIMEDOUT;
+		}
+	}
+
+	return 0;
+}
+
+static void _spi_transfer_delay_ns(u32 ns)
+{
+	if (!ns)
+		return;
+	if (ns <= 1000) {
+		ndelay(ns);
+	} else {
+		u32 us = DIV_ROUND_UP(ns, 1000);
+
+		if (us <= 10)
+			udelay(us);
+		else
+			usleep_range(us, us + DIV_ROUND_UP(us, 10));
+	}
+}
+
+static void _spi_transfer_cs_change_delay(struct spi_message *msg,
+					  struct spi_transfer *xfer)
+{
+	u32 delay = xfer->cs_change_delay;
+	u32 unit = xfer->cs_change_delay_unit;
+	u32 hz;
+
+	/* return early on "fast" mode - for everything but USECS */
+	if (!delay && unit != SPI_DELAY_UNIT_USECS)
+		return;
+
+	switch (unit) {
+	case SPI_DELAY_UNIT_USECS:
+		/* for compatibility use default of 10us */
+		if (!delay)
+			delay = 10000;
+		else
+			delay *= 1000;
+		break;
+	case SPI_DELAY_UNIT_NSECS: /* nothing to do here */
+		break;
+	case SPI_DELAY_UNIT_SCK:
+		/* if there is no effective speed know, then approximate
+		 * by underestimating with half the requested hz
+		 */
+		hz = xfer->effective_speed_hz ?: xfer->speed_hz / 2;
+		delay *= DIV_ROUND_UP(1000000000, hz);
+		break;
+	default:
+		dev_err_once(&msg->spi->dev,
+			     "Use of unsupported delay unit %i, using default of 10us\n",
+			     xfer->cs_change_delay_unit);
+		delay = 10000;
+	}
+	/* now sleep for the requested amount of time */
+	_spi_transfer_delay_ns(delay);
+}
+
 /*
  * spi_transfer_one_message - Default implementation of transfer_one_message()
  *
@@ -1006,7 +1157,6 @@
 	struct spi_transfer *xfer;
 	bool keep_cs = false;
 	int ret = 0;
-	unsigned long long ms = 1;
 	struct spi_statistics *statm = &ctlr->statistics;
 	struct spi_statistics *stats = &msg->spi->statistics;
 
@@ -1036,26 +1186,9 @@
 			}
 
 			if (ret > 0) {
-				ret = 0;
-				ms = 8LL * 1000LL * xfer->len;
-				do_div(ms, xfer->speed_hz);
-				ms += ms + 200; /* some tolerance */
-
-				if (ms > UINT_MAX)
-					ms = UINT_MAX;
-
-				ms = wait_for_completion_timeout(&ctlr->xfer_completion,
-								 msecs_to_jiffies(ms));
-			}
-
-			if (ms == 0) {
-				SPI_STATISTICS_INCREMENT_FIELD(statm,
-							       timedout);
-				SPI_STATISTICS_INCREMENT_FIELD(stats,
-							       timedout);
-				dev_err(&msg->spi->dev,
-					"SPI transfer timed out\n");
-				msg->status = -ETIMEDOUT;
+				ret = spi_transfer_wait(ctlr, msg, xfer);
+				if (ret < 0)
+					msg->status = ret;
 			}
 		} else {
 			if (xfer->len)
@@ -1069,14 +1202,8 @@
 		if (msg->status != -EINPROGRESS)
 			goto out;
 
-		if (xfer->delay_usecs) {
-			u16 us = xfer->delay_usecs;
-
-			if (us <= 10)
-				udelay(us);
-			else
-				usleep_range(us, us + DIV_ROUND_UP(us, 10));
-		}
+		if (xfer->delay_usecs)
+			_spi_transfer_delay_ns(xfer->delay_usecs * 1000);
 
 		if (xfer->cs_change) {
 			if (list_is_last(&xfer->transfer_list,
@@ -1084,7 +1211,7 @@
 				keep_cs = true;
 			} else {
 				spi_set_cs(msg->spi, false);
-				udelay(10);
+				_spi_transfer_cs_change_delay(msg, xfer);
 				spi_set_cs(msg->spi, true);
 			}
 		}
@@ -1138,8 +1265,9 @@
  */
 static void __spi_pump_messages(struct spi_controller *ctlr, bool in_kthread)
 {
-	unsigned long flags;
+	struct spi_message *msg;
 	bool was_busy = false;
+	unsigned long flags;
 	int ret;
 
 	/* Lock queue */
@@ -1198,10 +1326,10 @@
 	}
 
 	/* Extract head of queue */
-	ctlr->cur_msg =
-		list_first_entry(&ctlr->queue, struct spi_message, queue);
+	msg = list_first_entry(&ctlr->queue, struct spi_message, queue);
+	ctlr->cur_msg = msg;
 
-	list_del_init(&ctlr->cur_msg->queue);
+	list_del_init(&msg->queue);
 	if (ctlr->busy)
 		was_busy = true;
 	else
@@ -1228,37 +1356,42 @@
 		ret = ctlr->prepare_transfer_hardware(ctlr);
 		if (ret) {
 			dev_err(&ctlr->dev,
-				"failed to prepare transfer hardware\n");
+				"failed to prepare transfer hardware: %d\n",
+				ret);
 
 			if (ctlr->auto_runtime_pm)
 				pm_runtime_put(ctlr->dev.parent);
+
+			msg->status = ret;
+			spi_finalize_current_message(ctlr);
+
 			mutex_unlock(&ctlr->io_mutex);
 			return;
 		}
 	}
 
-	trace_spi_message_start(ctlr->cur_msg);
+	trace_spi_message_start(msg);
 
 	if (ctlr->prepare_message) {
-		ret = ctlr->prepare_message(ctlr, ctlr->cur_msg);
+		ret = ctlr->prepare_message(ctlr, msg);
 		if (ret) {
 			dev_err(&ctlr->dev, "failed to prepare message: %d\n",
 				ret);
-			ctlr->cur_msg->status = ret;
+			msg->status = ret;
 			spi_finalize_current_message(ctlr);
 			goto out;
 		}
 		ctlr->cur_msg_prepared = true;
 	}
 
-	ret = spi_map_msg(ctlr, ctlr->cur_msg);
+	ret = spi_map_msg(ctlr, msg);
 	if (ret) {
-		ctlr->cur_msg->status = ret;
+		msg->status = ret;
 		spi_finalize_current_message(ctlr);
 		goto out;
 	}
 
-	ret = ctlr->transfer_one_message(ctlr, ctlr->cur_msg);
+	ret = ctlr->transfer_one_message(ctlr, msg);
 	if (ret) {
 		dev_err(&ctlr->dev,
 			"failed to transfer one message from queue\n");
@@ -1285,10 +1418,32 @@
 	__spi_pump_messages(ctlr, true);
 }
 
+/**
+ * spi_set_thread_rt - set the controller to pump at realtime priority
+ * @ctlr: controller to boost priority of
+ *
+ * This can be called because the controller requested realtime priority
+ * (by setting the ->rt value before calling spi_register_controller()) or
+ * because a device on the bus said that its transfers needed realtime
+ * priority.
+ *
+ * NOTE: at the moment if any device on a bus says it needs realtime then
+ * the thread will be at realtime priority for all transfers on that
+ * controller.  If this eventually becomes a problem we may see if we can
+ * find a way to boost the priority only temporarily during relevant
+ * transfers.
+ */
+static void spi_set_thread_rt(struct spi_controller *ctlr)
+{
+	struct sched_param param = { .sched_priority = MAX_RT_PRIO / 2 };
+
+	dev_info(&ctlr->dev,
+		"will run message pump with realtime priority\n");
+	sched_setscheduler(ctlr->kworker_task, SCHED_FIFO, &param);
+}
+
 static int spi_init_queue(struct spi_controller *ctlr)
 {
-	struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
-
 	ctlr->running = false;
 	ctlr->busy = false;
 
@@ -1308,11 +1463,8 @@
 	 * request and the scheduling of the message pump thread. Without this
 	 * setting the message pump thread will remain at default priority.
 	 */
-	if (ctlr->rt) {
-		dev_info(&ctlr->dev,
-			"will run message pump with realtime priority\n");
-		sched_setscheduler(ctlr->kworker_task, SCHED_FIFO, &param);
-	}
+	if (ctlr->rt)
+		spi_set_thread_rt(ctlr);
 
 	return 0;
 }
@@ -1555,13 +1707,21 @@
 		spi->mode |= SPI_CPHA;
 	if (of_property_read_bool(nc, "spi-cpol"))
 		spi->mode |= SPI_CPOL;
-	if (of_property_read_bool(nc, "spi-cs-high"))
-		spi->mode |= SPI_CS_HIGH;
 	if (of_property_read_bool(nc, "spi-3wire"))
 		spi->mode |= SPI_3WIRE;
 	if (of_property_read_bool(nc, "spi-lsb-first"))
 		spi->mode |= SPI_LSB_FIRST;
 
+	/*
+	 * For descriptors associated with the device, polarity inversion is
+	 * handled in the gpiolib, so all chip selects are "active high" in
+	 * the logical sense, the gpiolib will invert the line if need be.
+	 */
+	if (ctlr->use_gpio_descriptors)
+		spi->mode |= SPI_CS_HIGH;
+	else if (of_property_read_bool(nc, "spi-cs-high"))
+		spi->mode |= SPI_CS_HIGH;
+
 	/* Device DUAL/QUAD mode */
 	if (!of_property_read_u32(nc, "spi-tx-bus-width", &value)) {
 		switch (value) {
@@ -1573,6 +1733,9 @@
 		case 4:
 			spi->mode |= SPI_TX_QUAD;
 			break;
+		case 8:
+			spi->mode |= SPI_TX_OCTAL;
+			break;
 		default:
 			dev_warn(&ctlr->dev,
 				"spi-tx-bus-width %d not supported\n",
@@ -1591,6 +1754,9 @@
 		case 4:
 			spi->mode |= SPI_RX_QUAD;
 			break;
+		case 8:
+			spi->mode |= SPI_RX_OCTAL;
+			break;
 		default:
 			dev_warn(&ctlr->dev,
 				"spi-rx-bus-width %d not supported\n",
@@ -1600,7 +1766,7 @@
 	}
 
 	if (spi_controller_is_slave(ctlr)) {
-		if (strcmp(nc->name, "slave")) {
+		if (!of_node_name_eq(nc, "slave")) {
 			dev_err(&ctlr->dev, "%pOF is not called 'slave'\n",
 				nc);
 			return -EINVAL;
@@ -1706,9 +1872,18 @@
 #endif
 
 #ifdef CONFIG_ACPI
-static void acpi_spi_parse_apple_properties(struct spi_device *spi)
+struct acpi_spi_lookup {
+	struct spi_controller 	*ctlr;
+	u32			max_speed_hz;
+	u32			mode;
+	int			irq;
+	u8			bits_per_word;
+	u8			chip_select;
+};
+
+static void acpi_spi_parse_apple_properties(struct acpi_device *dev,
+					    struct acpi_spi_lookup *lookup)
 {
-	struct acpi_device *dev = ACPI_COMPANION(&spi->dev);
 	const union acpi_object *obj;
 
 	if (!x86_apple_machine)
@@ -1716,35 +1891,46 @@
 
 	if (!acpi_dev_get_property(dev, "spiSclkPeriod", ACPI_TYPE_BUFFER, &obj)
 	    && obj->buffer.length >= 4)
-		spi->max_speed_hz  = NSEC_PER_SEC / *(u32 *)obj->buffer.pointer;
+		lookup->max_speed_hz  = NSEC_PER_SEC / *(u32 *)obj->buffer.pointer;
 
 	if (!acpi_dev_get_property(dev, "spiWordSize", ACPI_TYPE_BUFFER, &obj)
 	    && obj->buffer.length == 8)
-		spi->bits_per_word = *(u64 *)obj->buffer.pointer;
+		lookup->bits_per_word = *(u64 *)obj->buffer.pointer;
 
 	if (!acpi_dev_get_property(dev, "spiBitOrder", ACPI_TYPE_BUFFER, &obj)
 	    && obj->buffer.length == 8 && !*(u64 *)obj->buffer.pointer)
-		spi->mode |= SPI_LSB_FIRST;
+		lookup->mode |= SPI_LSB_FIRST;
 
 	if (!acpi_dev_get_property(dev, "spiSPO", ACPI_TYPE_BUFFER, &obj)
 	    && obj->buffer.length == 8 &&  *(u64 *)obj->buffer.pointer)
-		spi->mode |= SPI_CPOL;
+		lookup->mode |= SPI_CPOL;
 
 	if (!acpi_dev_get_property(dev, "spiSPH", ACPI_TYPE_BUFFER, &obj)
 	    && obj->buffer.length == 8 &&  *(u64 *)obj->buffer.pointer)
-		spi->mode |= SPI_CPHA;
+		lookup->mode |= SPI_CPHA;
 }
 
 static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
 {
-	struct spi_device *spi = data;
-	struct spi_controller *ctlr = spi->controller;
+	struct acpi_spi_lookup *lookup = data;
+	struct spi_controller *ctlr = lookup->ctlr;
 
 	if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
 		struct acpi_resource_spi_serialbus *sb;
+		acpi_handle parent_handle;
+		acpi_status status;
 
 		sb = &ares->data.spi_serial_bus;
 		if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_SPI) {
+
+			status = acpi_get_handle(NULL,
+						 sb->resource_source.string_ptr,
+						 &parent_handle);
+
+			if (ACPI_FAILURE(status) ||
+			    ACPI_HANDLE(ctlr->dev.parent) != parent_handle)
+				return -ENODEV;
+
 			/*
 			 * ACPI DeviceSelection numbering is handled by the
 			 * host controller driver in Windows and can vary
@@ -1757,25 +1943,25 @@
 						sb->device_selection);
 				if (cs < 0)
 					return cs;
-				spi->chip_select = cs;
+				lookup->chip_select = cs;
 			} else {
-				spi->chip_select = sb->device_selection;
+				lookup->chip_select = sb->device_selection;
 			}
 
-			spi->max_speed_hz = sb->connection_speed;
+			lookup->max_speed_hz = sb->connection_speed;
 
 			if (sb->clock_phase == ACPI_SPI_SECOND_PHASE)
-				spi->mode |= SPI_CPHA;
+				lookup->mode |= SPI_CPHA;
 			if (sb->clock_polarity == ACPI_SPI_START_HIGH)
-				spi->mode |= SPI_CPOL;
+				lookup->mode |= SPI_CPOL;
 			if (sb->device_polarity == ACPI_SPI_ACTIVE_HIGH)
-				spi->mode |= SPI_CS_HIGH;
+				lookup->mode |= SPI_CS_HIGH;
 		}
-	} else if (spi->irq < 0) {
+	} else if (lookup->irq < 0) {
 		struct resource r;
 
 		if (acpi_dev_resource_interrupt(ares, 0, &r))
-			spi->irq = r.start;
+			lookup->irq = r.start;
 	}
 
 	/* Always tell the ACPI core to skip this resource */
@@ -1785,7 +1971,9 @@
 static acpi_status acpi_register_spi_device(struct spi_controller *ctlr,
 					    struct acpi_device *adev)
 {
+	acpi_handle parent_handle = NULL;
 	struct list_head resource_list;
+	struct acpi_spi_lookup lookup = {};
 	struct spi_device *spi;
 	int ret;
 
@@ -1793,6 +1981,28 @@
 	    acpi_device_enumerated(adev))
 		return AE_OK;
 
+	lookup.ctlr		= ctlr;
+	lookup.irq		= -1;
+
+	INIT_LIST_HEAD(&resource_list);
+	ret = acpi_dev_get_resources(adev, &resource_list,
+				     acpi_spi_add_resource, &lookup);
+	acpi_dev_free_resource_list(&resource_list);
+
+	if (ret < 0)
+		/* found SPI in _CRS but it points to another controller */
+		return AE_OK;
+
+	if (!lookup.max_speed_hz &&
+	    !ACPI_FAILURE(acpi_get_parent(adev->handle, &parent_handle)) &&
+	    ACPI_HANDLE(ctlr->dev.parent) == parent_handle) {
+		/* Apple does not use _CRS but nested devices for SPI slaves */
+		acpi_spi_parse_apple_properties(adev, &lookup);
+	}
+
+	if (!lookup.max_speed_hz)
+		return AE_OK;
+
 	spi = spi_alloc_device(ctlr);
 	if (!spi) {
 		dev_err(&ctlr->dev, "failed to allocate SPI device for %s\n",
@@ -1801,19 +2011,11 @@
 	}
 
 	ACPI_COMPANION_SET(&spi->dev, adev);
-	spi->irq = -1;
-
-	INIT_LIST_HEAD(&resource_list);
-	ret = acpi_dev_get_resources(adev, &resource_list,
-				     acpi_spi_add_resource, spi);
-	acpi_dev_free_resource_list(&resource_list);
-
-	acpi_spi_parse_apple_properties(spi);
-
-	if (ret < 0 || !spi->max_speed_hz) {
-		spi_dev_put(spi);
-		return AE_OK;
-	}
+	spi->max_speed_hz	= lookup.max_speed_hz;
+	spi->mode		= lookup.mode;
+	spi->irq		= lookup.irq;
+	spi->bits_per_word	= lookup.bits_per_word;
+	spi->chip_select	= lookup.chip_select;
 
 	acpi_set_modalias(adev, acpi_device_hid(adev), spi->modalias,
 			  sizeof(spi->modalias));
@@ -1846,6 +2048,8 @@
 	return acpi_register_spi_device(ctlr, adev);
 }
 
+#define SPI_ACPI_ENUMERATE_MAX_DEPTH		32
+
 static void acpi_register_spi_devices(struct spi_controller *ctlr)
 {
 	acpi_status status;
@@ -1855,7 +2059,8 @@
 	if (!handle)
 		return;
 
-	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
+	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
+				     SPI_ACPI_ENUMERATE_MAX_DEPTH,
 				     acpi_spi_add_device, NULL, ctlr, NULL);
 	if (ACPI_FAILURE(status))
 		dev_warn(&ctlr->dev, "failed to enumerate SPI slaves\n");
@@ -1901,8 +2106,8 @@
 	return 1;
 }
 
-static ssize_t spi_slave_show(struct device *dev,
-			      struct device_attribute *attr, char *buf)
+static ssize_t slave_show(struct device *dev, struct device_attribute *attr,
+			  char *buf)
 {
 	struct spi_controller *ctlr = container_of(dev, struct spi_controller,
 						   dev);
@@ -1913,9 +2118,8 @@
 		       child ? to_spi_device(child)->modalias : NULL);
 }
 
-static ssize_t spi_slave_store(struct device *dev,
-			       struct device_attribute *attr, const char *buf,
-			       size_t count)
+static ssize_t slave_store(struct device *dev, struct device_attribute *attr,
+			   const char *buf, size_t count)
 {
 	struct spi_controller *ctlr = container_of(dev, struct spi_controller,
 						   dev);
@@ -1953,7 +2157,7 @@
 	return count;
 }
 
-static DEVICE_ATTR(slave, 0644, spi_slave_show, spi_slave_store);
+static DEVICE_ATTR_RW(slave);
 
 static struct attribute *spi_slave_attrs[] = {
 	&dev_attr_slave.attr,
@@ -1984,8 +2188,10 @@
  * __spi_alloc_controller - allocate an SPI master or slave controller
  * @dev: the controller, possibly using the platform_bus
  * @size: how much zeroed driver-private data to allocate; the pointer to this
- *	memory is in the driver_data field of the returned device,
- *	accessible with spi_controller_get_devdata().
+ *	memory is in the driver_data field of the returned device, accessible
+ *	with spi_controller_get_devdata(); the memory is cacheline aligned;
+ *	drivers granting DMA access to portions of their private data need to
+ *	round up @size using ALIGN(size, dma_get_cache_alignment()).
  * @slave: flag indicating whether to allocate an SPI master (false) or SPI
  *	slave (true) controller
  * Context: can sleep
@@ -2007,11 +2213,12 @@
 					      unsigned int size, bool slave)
 {
 	struct spi_controller	*ctlr;
+	size_t ctlr_size = ALIGN(sizeof(*ctlr), dma_get_cache_alignment());
 
 	if (!dev)
 		return NULL;
 
-	ctlr = kzalloc(size + sizeof(*ctlr), GFP_KERNEL);
+	ctlr = kzalloc(size + ctlr_size, GFP_KERNEL);
 	if (!ctlr)
 		return NULL;
 
@@ -2025,14 +2232,14 @@
 		ctlr->dev.class = &spi_master_class;
 	ctlr->dev.parent = dev;
 	pm_suspend_ignore_children(&ctlr->dev, true);
-	spi_controller_set_devdata(ctlr, &ctlr[1]);
+	spi_controller_set_devdata(ctlr, (void *)ctlr + ctlr_size);
 
 	return ctlr;
 }
 EXPORT_SYMBOL_GPL(__spi_alloc_controller);
 
 #ifdef CONFIG_OF
-static int of_spi_register_master(struct spi_controller *ctlr)
+static int of_spi_get_gpio_numbers(struct spi_controller *ctlr)
 {
 	int nb, i, *cs;
 	struct device_node *np = ctlr->dev.of_node;
@@ -2065,12 +2272,68 @@
 	return 0;
 }
 #else
-static int of_spi_register_master(struct spi_controller *ctlr)
+static int of_spi_get_gpio_numbers(struct spi_controller *ctlr)
 {
 	return 0;
 }
 #endif
 
+/**
+ * spi_get_gpio_descs() - grab chip select GPIOs for the master
+ * @ctlr: The SPI master to grab GPIO descriptors for
+ */
+static int spi_get_gpio_descs(struct spi_controller *ctlr)
+{
+	int nb, i;
+	struct gpio_desc **cs;
+	struct device *dev = &ctlr->dev;
+
+	nb = gpiod_count(dev, "cs");
+	ctlr->num_chipselect = max_t(int, nb, ctlr->num_chipselect);
+
+	/* No GPIOs at all is fine, else return the error */
+	if (nb == 0 || nb == -ENOENT)
+		return 0;
+	else if (nb < 0)
+		return nb;
+
+	cs = devm_kcalloc(dev, ctlr->num_chipselect, sizeof(*cs),
+			  GFP_KERNEL);
+	if (!cs)
+		return -ENOMEM;
+	ctlr->cs_gpiods = cs;
+
+	for (i = 0; i < nb; i++) {
+		/*
+		 * Most chipselects are active low, the inverted
+		 * semantics are handled by special quirks in gpiolib,
+		 * so initializing them GPIOD_OUT_LOW here means
+		 * "unasserted", in most cases this will drive the physical
+		 * line high.
+		 */
+		cs[i] = devm_gpiod_get_index_optional(dev, "cs", i,
+						      GPIOD_OUT_LOW);
+		if (IS_ERR(cs[i]))
+			return PTR_ERR(cs[i]);
+
+		if (cs[i]) {
+			/*
+			 * If we find a CS GPIO, name it after the device and
+			 * chip select line.
+			 */
+			char *gpioname;
+
+			gpioname = devm_kasprintf(dev, GFP_KERNEL, "%s CS%d",
+						  dev_name(dev), i);
+			if (!gpioname)
+				return -ENOMEM;
+			gpiod_set_consumer_name(cs[i], gpioname);
+		}
+	}
+
+	return 0;
+}
+
 static int spi_controller_check_ops(struct spi_controller *ctlr)
 {
 	/*
@@ -2118,7 +2381,7 @@
 {
 	struct device		*dev = ctlr->dev.parent;
 	struct boardinfo	*bi;
-	int			status = -ENODEV;
+	int			status;
 	int			id, first_dynamic;
 
 	if (!dev)
@@ -2132,17 +2395,6 @@
 	if (status)
 		return status;
 
-	if (!spi_controller_is_slave(ctlr)) {
-		status = of_spi_register_master(ctlr);
-		if (status)
-			return status;
-	}
-
-	/* even if it's just one always-selected device, there must
-	 * be at least one chipselect
-	 */
-	if (ctlr->num_chipselect == 0)
-		return -EINVAL;
 	if (ctlr->bus_num >= 0) {
 		/* devices with a fixed bus num must check-in with the num */
 		mutex_lock(&board_lock);
@@ -2194,6 +2446,32 @@
 	 * registration fails if the bus ID is in use.
 	 */
 	dev_set_name(&ctlr->dev, "spi%u", ctlr->bus_num);
+
+	if (!spi_controller_is_slave(ctlr)) {
+		if (ctlr->use_gpio_descriptors) {
+			status = spi_get_gpio_descs(ctlr);
+			if (status)
+				return status;
+			/*
+			 * A controller using GPIO descriptors always
+			 * supports SPI_CS_HIGH if need be.
+			 */
+			ctlr->mode_bits |= SPI_CS_HIGH;
+		} else {
+			/* Legacy code path for GPIOs from DT */
+			status = of_spi_get_gpio_numbers(ctlr);
+			if (status)
+				return status;
+		}
+	}
+
+	/*
+	 * Even if it's just one always-selected device, there must
+	 * be at least one chipselect.
+	 */
+	if (!ctlr->num_chipselect)
+		return -EINVAL;
+
 	status = device_add(&ctlr->dev);
 	if (status < 0) {
 		/* free bus id */
@@ -2303,7 +2581,6 @@
 {
 	struct spi_controller *found;
 	int id = ctlr->bus_num;
-	int dummy;
 
 	/* First make sure that this controller was ever added */
 	mutex_lock(&board_lock);
@@ -2317,7 +2594,7 @@
 	list_del(&ctlr->list);
 	mutex_unlock(&board_lock);
 
-	dummy = device_for_each_child(&ctlr->dev, NULL, __unregister);
+	device_for_each_child(&ctlr->dev, NULL, __unregister);
 	device_unregister(&ctlr->dev);
 	/* free bus id */
 	mutex_lock(&board_lock);
@@ -2466,12 +2743,9 @@
  */
 void spi_res_release(struct spi_controller *ctlr, struct spi_message *message)
 {
-	struct spi_res *res;
+	struct spi_res *res, *tmp;
 
-	while (!list_empty(&message->resources)) {
-		res = list_last_entry(&message->resources,
-				      struct spi_res, entry);
-
+	list_for_each_entry_safe_reverse(res, tmp, &message->resources, entry) {
 		if (res->release)
 			res->release(ctlr, message, res->data);
 
@@ -2535,8 +2809,7 @@
 
 	/* allocate the structure using spi_res */
 	rxfer = spi_res_alloc(msg->spi, __spi_replace_transfers_release,
-			      insert * sizeof(struct spi_transfer)
-			      + sizeof(struct spi_replaced_transfers)
+			      struct_size(rxfer, inserted_transfers, insert)
 			      + extradatasize,
 			      gfp);
 	if (!rxfer)
@@ -2626,11 +2899,6 @@
 	size_t offset;
 	size_t count, i;
 
-	/* warn once about this fact that we are splitting a transfer */
-	dev_warn_once(&msg->spi->dev,
-		      "spi_transfer of length %i exceed max length of %zu - needed to split transfers\n",
-		      xfer->len, maxsize);
-
 	/* calculate how many we have to replace */
 	count = DIV_ROUND_UP(xfer->len, maxsize);
 
@@ -2779,14 +3047,23 @@
 	/* if it is SPI_3WIRE mode, DUAL and QUAD should be forbidden
 	 */
 	if ((spi->mode & SPI_3WIRE) && (spi->mode &
-		(SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)))
+		(SPI_TX_DUAL | SPI_TX_QUAD | SPI_TX_OCTAL |
+		 SPI_RX_DUAL | SPI_RX_QUAD | SPI_RX_OCTAL)))
 		return -EINVAL;
 	/* help drivers fail *cleanly* when they need options
 	 * that aren't supported with their current controller
+	 * SPI_CS_WORD has a fallback software implementation,
+	 * so it is ignored here.
 	 */
-	bad_bits = spi->mode & ~spi->controller->mode_bits;
+	bad_bits = spi->mode & ~(spi->controller->mode_bits | SPI_CS_WORD);
+	/* nothing prevents from working with active-high CS in case if it
+	 * is driven by GPIO.
+	 */
+	if (gpio_is_valid(spi->cs_gpio))
+		bad_bits &= ~SPI_CS_HIGH;
 	ugly_bits = bad_bits &
-		    (SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD);
+		    (SPI_TX_DUAL | SPI_TX_QUAD | SPI_TX_OCTAL |
+		     SPI_RX_DUAL | SPI_RX_QUAD | SPI_RX_OCTAL);
 	if (ugly_bits) {
 		dev_warn(&spi->dev,
 			 "setup: ignoring unsupported mode bits %x\n",
@@ -2816,6 +3093,11 @@
 
 	spi_set_cs(spi, false);
 
+	if (spi->rt && !spi->controller->rt) {
+		spi->controller->rt = true;
+		spi_set_thread_rt(spi->controller);
+	}
+
 	dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s%u bits/w, %u Hz max --> %d\n",
 			(int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
 			(spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
@@ -2829,6 +3111,21 @@
 }
 EXPORT_SYMBOL_GPL(spi_setup);
 
+/**
+ * spi_set_cs_timing - configure CS setup, hold, and inactive delays
+ * @spi: the device that requires specific CS timing configuration
+ * @setup: CS setup time in terms of clock count
+ * @hold: CS hold time in terms of clock count
+ * @inactive_dly: CS inactive delay between transfers in terms of clock count
+ */
+void spi_set_cs_timing(struct spi_device *spi, u8 setup, u8 hold,
+		       u8 inactive_dly)
+{
+	if (spi->controller->set_cs_timing)
+		spi->controller->set_cs_timing(spi, setup, hold, inactive_dly);
+}
+EXPORT_SYMBOL_GPL(spi_set_cs_timing);
+
 static int __spi_validate(struct spi_device *spi, struct spi_message *message)
 {
 	struct spi_controller *ctlr = spi->controller;
@@ -2838,6 +3135,36 @@
 	if (list_empty(&message->transfers))
 		return -EINVAL;
 
+	/* If an SPI controller does not support toggling the CS line on each
+	 * transfer (indicated by the SPI_CS_WORD flag) or we are using a GPIO
+	 * for the CS line, we can emulate the CS-per-word hardware function by
+	 * splitting transfers into one-word transfers and ensuring that
+	 * cs_change is set for each transfer.
+	 */
+	if ((spi->mode & SPI_CS_WORD) && (!(ctlr->mode_bits & SPI_CS_WORD) ||
+					  spi->cs_gpiod ||
+					  gpio_is_valid(spi->cs_gpio))) {
+		size_t maxsize;
+		int ret;
+
+		maxsize = (spi->bits_per_word + 7) / 8;
+
+		/* spi_split_transfers_maxsize() requires message->spi */
+		message->spi = spi;
+
+		ret = spi_split_transfers_maxsize(ctlr, message, maxsize,
+						  GFP_KERNEL);
+		if (ret)
+			return ret;
+
+		list_for_each_entry(xfer, &message->transfers, transfer_list) {
+			/* don't change cs_change on the last entry in the list */
+			if (list_is_last(&xfer->transfer_list, &message->transfers))
+				break;
+			xfer->cs_change = 1;
+		}
+	}
+
 	/* Half-duplex links include original MicroWire, and ones with
 	 * only one data pin like SPI_3WIRE (switches direction) or where
 	 * either MOSI or MISO is missing.  They can also be caused by
@@ -2862,17 +3189,18 @@
 	 * it is not set for this transfer.
 	 * Set transfer tx_nbits and rx_nbits as single transfer default
 	 * (SPI_NBITS_SINGLE) if it is not set for this transfer.
+	 * Ensure transfer word_delay is at least as long as that required by
+	 * device itself.
 	 */
 	message->frame_length = 0;
 	list_for_each_entry(xfer, &message->transfers, transfer_list) {
+		xfer->effective_speed_hz = 0;
 		message->frame_length += xfer->len;
 		if (!xfer->bits_per_word)
 			xfer->bits_per_word = spi->bits_per_word;
 
 		if (!xfer->speed_hz)
 			xfer->speed_hz = spi->max_speed_hz;
-		if (!xfer->speed_hz)
-			xfer->speed_hz = ctlr->max_speed_hz;
 
 		if (ctlr->max_speed_hz && xfer->speed_hz > ctlr->max_speed_hz)
 			xfer->speed_hz = ctlr->max_speed_hz;
@@ -2932,6 +3260,9 @@
 				!(spi->mode & SPI_RX_QUAD))
 				return -EINVAL;
 		}
+
+		if (xfer->word_delay_usecs < spi->word_delay_usecs)
+			xfer->word_delay_usecs = spi->word_delay_usecs;
 	}
 
 	message->status = -EINPROGRESS;
@@ -3323,35 +3654,26 @@
 
 /*-------------------------------------------------------------------------*/
 
-#if IS_ENABLED(CONFIG_OF_DYNAMIC)
-static int __spi_of_device_match(struct device *dev, void *data)
-{
-	return dev->of_node == data;
-}
-
+#if IS_ENABLED(CONFIG_OF)
 /* must call put_device() when done with returned spi_device device */
-static struct spi_device *of_find_spi_device_by_node(struct device_node *node)
+struct spi_device *of_find_spi_device_by_node(struct device_node *node)
 {
-	struct device *dev = bus_find_device(&spi_bus_type, NULL, node,
-						__spi_of_device_match);
+	struct device *dev = bus_find_device_by_of_node(&spi_bus_type, node);
+
 	return dev ? to_spi_device(dev) : NULL;
 }
+EXPORT_SYMBOL_GPL(of_find_spi_device_by_node);
+#endif /* IS_ENABLED(CONFIG_OF) */
 
-static int __spi_of_controller_match(struct device *dev, const void *data)
-{
-	return dev->of_node == data;
-}
-
+#if IS_ENABLED(CONFIG_OF_DYNAMIC)
 /* the spi controllers are not using spi_bus, so we find it with another way */
 static struct spi_controller *of_find_spi_controller_by_node(struct device_node *node)
 {
 	struct device *dev;
 
-	dev = class_find_device(&spi_master_class, NULL, node,
-				__spi_of_controller_match);
+	dev = class_find_device_by_of_node(&spi_master_class, node);
 	if (!dev && IS_ENABLED(CONFIG_SPI_SLAVE))
-		dev = class_find_device(&spi_slave_class, NULL, node,
-					__spi_of_controller_match);
+		dev = class_find_device_by_of_node(&spi_slave_class, node);
 	if (!dev)
 		return NULL;
 
@@ -3422,11 +3744,6 @@
 	return ACPI_COMPANION(dev->parent) == data;
 }
 
-static int spi_acpi_device_match(struct device *dev, void *data)
-{
-	return ACPI_COMPANION(dev) == data;
-}
-
 static struct spi_controller *acpi_spi_find_controller_by_adev(struct acpi_device *adev)
 {
 	struct device *dev;
@@ -3446,8 +3763,7 @@
 {
 	struct device *dev;
 
-	dev = bus_find_device(&spi_bus_type, NULL, adev, spi_acpi_device_match);
-
+	dev = bus_find_device_by_acpi_dev(&spi_bus_type, adev);
 	return dev ? to_spi_device(dev) : NULL;
 }
 
@@ -3540,4 +3856,3 @@
  * include needing to have boardinfo data structures be much more public.
  */
 postcore_initcall(spi_init);
-