[PATCH v2 -next 0/3] spi: Introduce BPF based SPI mockup controller

[PATCH v2 -next 0/3] spi: Introduce BPF based SPI mockup controller

[Zhang Xiaoxu]

This series Introduce a BPF based SPI mockup controller, which can be
used for testing SPI drivers without real device.

The testsuite for SPI drivers will be post in other series, with also
support for I2C and PCI bus device drivers.

patch 1-2 introduce BPF based SPI mockup controller
patch 3 add the document

v1->v2:
  Use the new _controller() API
  P1. Move the license identifier to the entrie comment
  P2. Inherit tx_nbits/rx_nbits/cs_off/cs_change from the
      spi_transfer to the tracepoint
  P3. Removed.
  P4. Update the Document.

Wei Yongjun (3):
  spi: mockup: Add SPI controller testing driver
  spi: mockup: Add writeable tracepoint for spi transfer
  spi: mockup: Add documentation

 Documentation/spi/index.rst       |   1 +
 Documentation/spi/spi-mockup.rst  | 174 ++++++++++++++++++++
 drivers/spi/Kconfig               |  13 ++
 drivers/spi/Makefile              |   1 +
 drivers/spi/spi-mockup.c          | 260 ++++++++++++++++++++++++++++++
 include/linux/spi/spi-mockup.h    |  17 ++
 include/trace/events/spi_mockup.h |  31 ++++
 7 files changed, 497 insertions(+)
 create mode 100644 Documentation/spi/spi-mockup.rst
 create mode 100644 drivers/spi/spi-mockup.c
 create mode 100644 include/linux/spi/spi-mockup.h
 create mode 100644 include/trace/events/spi_mockup.h

-- 
2.34.1

[PATCH v2 -next 1/3] spi: mockup: Add SPI controller testing driver

[Zhang Xiaoxu]

From: Wei Yongjun <weiyongjun1@huawei.com>

This enables SPI controller Testing driver, which provides a way to
test SPI subsystem.

This is accomplished by executing the following command:

$ echo adcxx1s 0 > /sys/class/spi_master/spi0/new_device

The name of the target driver and its chip select were used to
instantiate the device.

$ ls /sys/bus/spi/devices/spi0.0/hwmon/hwmon0/ -l
 total 0
 lrwxrwxrwx 1 root root    0 Aug 10 08:58 device -> ../../../spi0.0
 drwxr-xr-x 2 root root    0 Aug 10 08:58 power
 lrwxrwxrwx 1 root root    0 Aug 10 08:58 subsystem -> ../../../../../../../../class/hwmon
 -rw-r--r-- 1 root root 4096 Aug 10 08:58 uevent

Remove target device by executing the following command:
$ echo 0 > /sys/class/spi_master/spi0/delete_device

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
---
 drivers/spi/Kconfig      |  12 +++
 drivers/spi/Makefile     |   1 +
 drivers/spi/spi-mockup.c | 212 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 225 insertions(+)
 create mode 100644 drivers/spi/spi-mockup.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 8962b2557615..1768e57f0088 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -1185,6 +1185,18 @@ config SPI_TLE62X0
 	  sysfs interface, with each line presented as a kind of GPIO
 	  exposing both switch control and diagnostic feedback.
 
+config SPI_MOCKUP
+	tristate "SPI controller Testing Driver"
+	depends on OF
+	help
+	  This enables SPI controller testing driver, which provides a way to
+	  test SPI subsystem.
+
+	  If you do build this module, be sure to read the notes and warnings
+	  in <file:Documentation/spi/spi-mockup.rst>.
+
+	  If you don't know what to do here, definitely say N.
+
 #
 # Add new SPI protocol masters in alphabetical order above this line
 #
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 080c2c1b3ec1..8ce94e7295b7 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -12,6 +12,7 @@ obj-$(CONFIG_SPI_MEM)			+= spi-mem.o
 obj-$(CONFIG_SPI_MUX)			+= spi-mux.o
 obj-$(CONFIG_SPI_SPIDEV)		+= spidev.o
 obj-$(CONFIG_SPI_LOOPBACK_TEST)		+= spi-loopback-test.o
+obj-$(CONFIG_SPI_MOCKUP)		+= spi-mockup.o
 
 # SPI master controller drivers (bus)
 obj-$(CONFIG_SPI_ALTERA)		+= spi-altera-platform.o
diff --git a/drivers/spi/spi-mockup.c b/drivers/spi/spi-mockup.c
new file mode 100644
index 000000000000..4debfd1fb9fd
--- /dev/null
+++ b/drivers/spi/spi-mockup.c
@@ -0,0 +1,212 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * SPI controller Testing Driver
+ *
+ * Copyright(c) 2022 Huawei Technologies Co., Ltd.
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+
+#define MOCKUP_CHIPSELECT_MAX		8
+
+struct mockup_spi {
+	struct mutex lock;
+	struct spi_device *devs[MOCKUP_CHIPSELECT_MAX];
+};
+
+static struct spi_controller *to_spi_controller(struct device *dev)
+{
+	return container_of(dev, struct spi_controller, dev);
+}
+
+static ssize_t
+new_device_store(struct device *dev, struct device_attribute *attr,
+		 const char *buf, size_t count)
+{
+	struct spi_controller *ctrl = to_spi_controller(dev);
+	struct spi_board_info info;
+	struct mockup_spi *mock;
+	struct spi_device *spi;
+	char *blank, end;
+	int status;
+
+	memset(&info, 0, sizeof(struct spi_board_info));
+
+	blank = strchr(buf, ' ');
+	if (!blank) {
+		dev_err(dev, "%s: Extra parameters\n", "new_device");
+		return -EINVAL;
+	}
+
+	if (blank - buf > SPI_NAME_SIZE - 1) {
+		dev_err(dev, "%s: Invalid device name\n", "new_device");
+		return -EINVAL;
+	}
+
+	memcpy(info.modalias, buf, blank - buf);
+
+	status = sscanf(++blank, "%hi%c", &info.chip_select, &end);
+	if (status < 1) {
+		dev_err(dev, "%s: Can't parse SPI chipselect\n", "new_device");
+		return -EINVAL;
+	}
+
+	if (status > 1 && end != '\n') {
+		dev_err(dev, "%s: Extra parameters\n", "new_device");
+		return -EINVAL;
+	}
+
+	if (info.chip_select >= ctrl->num_chipselect) {
+		dev_err(dev, "%s: Invalid chip_select\n", "new_device");
+		return -EINVAL;
+	}
+
+	mock = spi_controller_get_devdata(ctrl);
+	mutex_lock(&mock->lock);
+
+	if (mock->devs[info.chip_select]) {
+		dev_err(dev, "%s: Chipselect %d already in use\n",
+			"new_device", info.chip_select);
+		mutex_unlock(&mock->lock);
+		return -EINVAL;
+	}
+
+	spi = spi_new_device(ctrl, &info);
+	if (!spi) {
+		mutex_unlock(&mock->lock);
+		return -ENOMEM;
+	}
+	mock->devs[info.chip_select] = spi;
+
+	mutex_unlock(&mock->lock);
+
+	dev_info(dev, "%s: Instantiated device %s at 0x%02x\n", "new_device",
+		 info.modalias, info.chip_select);
+
+	return count;
+}
+static DEVICE_ATTR_WO(new_device);
+
+static ssize_t
+delete_device_store(struct device *dev, struct device_attribute *attr,
+		    const char *buf, size_t count)
+{
+	struct spi_controller *ctrl = to_spi_controller(dev);
+	struct mockup_spi *mock;
+	struct spi_device *spi;
+	unsigned short chip;
+	char end;
+	int res;
+
+	/* Parse parameters, reject extra parameters */
+	res = sscanf(buf, "%hi%c", &chip, &end);
+	if (res < 1) {
+		dev_err(dev, "%s: Can't parse SPI address\n", "delete_device");
+		return -EINVAL;
+	}
+	if (res > 1  && end != '\n') {
+		dev_err(dev, "%s: Extra parameters\n", "delete_device");
+		return -EINVAL;
+	}
+
+	if (chip >= ctrl->num_chipselect) {
+		dev_err(dev, "%s: Invalid chip_select\n", "delete_device");
+		return -EINVAL;
+	}
+
+	mock = spi_controller_get_devdata(ctrl);
+	mutex_lock(&mock->lock);
+
+	spi = mock->devs[chip];
+	if (!spi) {
+		mutex_unlock(&mock->lock);
+		dev_err(dev, "%s: Invalid chip_select\n", "delete_device");
+		return -ENOENT;
+	}
+
+	dev_info(dev, "%s: Deleting device %s at 0x%02hx\n", "delete_device",
+		 dev_name(&spi->dev), chip);
+
+	spi_unregister_device(spi);
+	mock->devs[chip] = NULL;
+
+	mutex_unlock(&mock->lock);
+
+	return count;
+}
+static DEVICE_ATTR_WO(delete_device);
+
+static struct attribute *spi_mockup_attrs[] = {
+	&dev_attr_new_device.attr,
+	&dev_attr_delete_device.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(spi_mockup);
+
+static int spi_mockup_transfer(struct spi_controller *ctrl,
+			       struct spi_message *msg)
+{
+	msg->status = 0;
+	spi_finalize_current_message(ctrl);
+
+	return 0;
+}
+
+static int spi_mockup_probe(struct platform_device *pdev)
+{
+	struct spi_controller *ctrl;
+	struct mockup_spi *mock;
+	int ret;
+
+	ctrl = spi_alloc_host(&pdev->dev, sizeof(struct mockup_spi));
+	if (!ctrl) {
+		pr_err("failed to alloc spi controller\n");
+		return -ENOMEM;
+	}
+
+	platform_set_drvdata(pdev, ctrl);
+
+	ctrl->dev.of_node = pdev->dev.of_node;
+	ctrl->dev.groups = spi_mockup_groups;
+	ctrl->num_chipselect = MOCKUP_CHIPSELECT_MAX;
+	ctrl->mode_bits = SPI_MODE_USER_MASK;
+	ctrl->bus_num = 0;
+	ctrl->transfer_one_message = spi_mockup_transfer;
+
+	mock = spi_controller_get_devdata(ctrl);
+	mutex_init(&mock->lock);
+
+	ret = devm_spi_register_controller(&pdev->dev, ctrl);
+	if (ret) {
+		spi_controller_put(ctrl);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id spi_mockup_match[] = {
+	{ .compatible = "spi-mockup", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, spi_mockup_match);
+
+static struct platform_driver spi_mockup_driver = {
+	.probe = spi_mockup_probe,
+	.driver = {
+		.name = "spi-mockup",
+		.of_match_table = spi_mockup_match,
+	},
+};
+module_platform_driver(spi_mockup_driver);
+
+MODULE_AUTHOR("Wei Yongjun <weiyongjun1@huawei.com>");
+MODULE_DESCRIPTION("SPI controller Testing Driver");
+MODULE_LICENSE("GPL");
-- 
2.34.1

[PATCH v2 -next 2/3] spi: mockup: Add writeable tracepoint for spi transfer

[Zhang Xiaoxu]

From: Wei Yongjun <weiyongjun1@huawei.com>

Add writeable tracepoint for transfer_one_message(), then bpf program
can be used to control read and write data from spi host, as mockup
chip's expectation.

For example:

  #include "vmlinux.h"
  #include <bpf/bpf_helpers.h>
  #include <bpf/bpf_tracing.h>

  SEC("raw_tp.w/spi_transfer_writeable")
  int BPF_PROG(spi_transfer_writeable_test, struct spi_msg_ctx *msg,
               u8 chip, unsigned int len)
  {
      if (msg->tx_nbits)
          msg->data[0] = 0x20;

      return 0;
  }

  char LICENSE[] SEC("license") = "GPL";

This will be useful for writing spi device mockup backend.

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
---
 drivers/spi/Kconfig               |  1 +
 drivers/spi/spi-mockup.c          | 52 +++++++++++++++++++++++++++++--
 include/linux/spi/spi-mockup.h    | 17 ++++++++++
 include/trace/events/spi_mockup.h | 31 ++++++++++++++++++
 4 files changed, 99 insertions(+), 2 deletions(-)
 create mode 100644 include/linux/spi/spi-mockup.h
 create mode 100644 include/trace/events/spi_mockup.h

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 1768e57f0088..608e224e52ef 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -1188,6 +1188,7 @@ config SPI_TLE62X0
 config SPI_MOCKUP
 	tristate "SPI controller Testing Driver"
 	depends on OF
+	select BPF_EVENTS
 	help
 	  This enables SPI controller testing driver, which provides a way to
 	  test SPI subsystem.
diff --git a/drivers/spi/spi-mockup.c b/drivers/spi/spi-mockup.c
index 4debfd1fb9fd..3835012e2ee8 100644
--- a/drivers/spi/spi-mockup.c
+++ b/drivers/spi/spi-mockup.c
@@ -14,6 +14,9 @@
 #include <linux/platform_device.h>
 #include <linux/spi/spi.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/spi_mockup.h>
+
 #define MOCKUP_CHIPSELECT_MAX		8
 
 struct mockup_spi {
@@ -150,13 +153,58 @@ static struct attribute *spi_mockup_attrs[] = {
 };
 ATTRIBUTE_GROUPS(spi_mockup);
 
+static int spi_mockup_transfer_writeable(struct spi_message *msg)
+{
+	struct spi_msg_ctx *ctx;
+	struct spi_transfer *t;
+	int ret = 0;
+
+	ctx = kmalloc(sizeof(*ctx), GFP_ATOMIC);
+	if (!ctx)
+		return -ENOMEM;
+
+	list_for_each_entry(t, &msg->transfers, transfer_list) {
+		if (t->len > SPI_BUFSIZ_MAX)
+			return -E2BIG;
+
+		memset(ctx, 0, sizeof(*ctx));
+		ctx->cs_off = t->cs_off;
+		ctx->cs_change = t->cs_change;
+		ctx->tx_nbits = t->tx_nbits;
+		ctx->rx_nbits = t->rx_nbits;
+
+		if (t->tx_nbits)
+			memcpy(ctx->data, t->tx_buf, t->len);
+
+		trace_spi_transfer_writeable(ctx, msg->spi->chip_select, t->len);
+
+		if (ctx->ret) {
+			ret = ctx->ret;
+			break;
+		}
+
+		if (t->rx_nbits)
+			memcpy(t->rx_buf, ctx->data, t->len);
+		msg->actual_length += t->len;
+	}
+
+	kfree(ctx);
+
+	return ret;
+}
+
 static int spi_mockup_transfer(struct spi_controller *ctrl,
 			       struct spi_message *msg)
 {
-	msg->status = 0;
+	int ret = 0;
+
+	if (trace_spi_transfer_writeable_enabled())
+		ret = spi_mockup_transfer_writeable(msg);
+
+	msg->status = ret;
 	spi_finalize_current_message(ctrl);
 
-	return 0;
+	return ret;
 }
 
 static int spi_mockup_probe(struct platform_device *pdev)
diff --git a/include/linux/spi/spi-mockup.h b/include/linux/spi/spi-mockup.h
new file mode 100644
index 000000000000..224894b416fb
--- /dev/null
+++ b/include/linux/spi/spi-mockup.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __LINUX_SPI_MOCKUP_H
+#define __LINUX_SPI_MOCKUP_H
+
+#define SPI_BUFSIZ_MAX		0x1000
+
+struct spi_msg_ctx {
+	int ret;
+	unsigned cs_off:1;
+	unsigned cs_change:1;
+	unsigned tx_nbits:3;
+	unsigned rx_nbits:3;
+	__u8 data[SPI_BUFSIZ_MAX];
+};
+
+#endif
diff --git a/include/trace/events/spi_mockup.h b/include/trace/events/spi_mockup.h
new file mode 100644
index 000000000000..46debf26a5e3
--- /dev/null
+++ b/include/trace/events/spi_mockup.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * SPI mockup controller transfer writeable tracepoint
+ *
+ * Copyright(c) 2022 Huawei Technologies Co., Ltd.
+ */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM spi_mockup
+
+#if !defined(_TRACE_SPI_MOCKUP_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_SPI_MOCKUP_H
+
+#include <linux/tracepoint.h>
+#include <linux/spi/spi-mockup.h>
+
+#ifndef DECLARE_TRACE_WRITABLE
+#define DECLARE_TRACE_WRITABLE(call, proto, args, size) \
+	DECLARE_TRACE(call, PARAMS(proto), PARAMS(args))
+#endif
+
+DECLARE_TRACE_WRITABLE(spi_transfer_writeable,
+	TP_PROTO(struct spi_msg_ctx *msg, u8 chip_select, unsigned int len),
+	TP_ARGS(msg, chip_select, len),
+	sizeof(struct spi_msg_ctx)
+);
+
+#endif /* _TRACE_SPI_MOCKUP_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
-- 
2.34.1

[PATCH v2 -next 3/3] spi: mockup: Add documentation

[Zhang Xiaoxu]

From: Wei Yongjun <weiyongjun1@huawei.com>

Add documentation for the SPI mockup controller driver.
This include the tutorial for how to mockup a api device.

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
---
 Documentation/spi/index.rst      |   1 +
 Documentation/spi/spi-mockup.rst | 174 +++++++++++++++++++++++++++++++
 2 files changed, 175 insertions(+)
 create mode 100644 Documentation/spi/spi-mockup.rst

diff --git a/Documentation/spi/index.rst b/Documentation/spi/index.rst
index 06c34ea11bcf..a8f4f5cd0f09 100644
--- a/Documentation/spi/index.rst
+++ b/Documentation/spi/index.rst
@@ -13,6 +13,7 @@ Serial Peripheral Interface (SPI)
    pxa2xx
    spi-lm70llp
    spi-sc18is602
+   spi-mockup
 
 .. only::  subproject and html
 
diff --git a/Documentation/spi/spi-mockup.rst b/Documentation/spi/spi-mockup.rst
new file mode 100644
index 000000000000..5e720de19991
--- /dev/null
+++ b/Documentation/spi/spi-mockup.rst
@@ -0,0 +1,174 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==========
+spi-mockup
+==========
+
+Description
+===========
+
+This module is a very simple fake SPI controller driver. It implements
+a BPF based interface to mockup SPI device.
+
+No hardware is needed nor associated with this module. It will respond
+spi message by BPF program attached to spi_transfer_writeable tracepoint
+by reading from or writing BPF maps.
+
+The typical use-case is like this:
+        1. load EBPF program as device's backend
+        2. create target chip device
+
+Example
+=======
+
+This example show how to mock a MTD device by using spi-mockup driver.
+
+Compile your copy of the kernel source. Make sure to configure the spi-mockup
+and the target chip driver as a module.
+
+Write a BPF program as device's backup.
+
+::
+
+  #define MCHP23K256_CMD_WRITE_STATUS   0x01
+  #define MCHP23K256_CMD_WRITE          0x02
+  #define MCHP23K256_CMD_READ           0x03
+
+  #define CHIP_REGS_SIZE		0x20000
+
+  #define MAX_CMD_SIZE		        4
+
+  struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, CHIP_REGS_SIZE);
+	__type(key, __u32);
+	__type(value, __u8);
+  } regs_mchp23k256 SEC(".maps");
+
+  static unsigned int chip_reg = 0;
+
+  static int spi_transfer_read(struct spi_msg_ctx *msg, unsigned int len)
+  {
+	int i, key;
+	u8 *reg;
+
+	for (i = 0; i < len && i < sizeof(msg->data); i++) {
+		key = i + chip_reg;
+
+		reg = bpf_map_lookup_elem(&regs_mchp23k256, &key);
+		if (!reg) {
+			bpf_printk("key %d not exists", key);
+			return -EINVAL;
+		}
+
+		msg->data[i] = *reg;
+	}
+
+	return 0;
+  }
+
+  static int spi_transfer_write(struct spi_msg_ctx *msg, unsigned int len)
+  {
+	u8 opcode = msg->data[0], value;
+	int i, key;
+
+	switch (opcode) {
+	case MCHP23K256_CMD_READ:
+	case MCHP23K256_CMD_WRITE:
+		if (len < 2)
+			return -EINVAL;
+
+		chip_reg = 0;
+		for (i = 0; i < MAX_CMD_SIZE && i < len - 1; i++)
+			chip_reg = (chip_reg << 8) + msg->data[1 + i];
+
+		return 0;
+	case MCHP23K256_CMD_WRITE_STATUS:
+		// ignore write status
+		return 0;
+	default:
+		break;
+	}
+
+	for (i = 0; i < len && i < sizeof(msg->data); i++) {
+		value = msg->data[i];
+		key = chip_reg + i;
+
+		if (bpf_map_update_elem(&regs_mchp23k256, &key, &value,
+					BPF_EXIST)) {
+			bpf_printk("key %d not exists", key);
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+  }
+
+  SEC("raw_tp.w/spi_transfer_writeable")
+  int BPF_PROG(mtd_mchp23k256, struct spi_msg_ctx *msg, u8 chip, unsigned int len)
+  {
+	int ret = 0;
+
+	if (msg->tx_nbits)
+		ret = spi_transfer_write(msg, len);
+	else if (msg->rx_nbits)
+		ret = spi_transfer_read(msg, len);
+
+	return ret;
+  }
+
+  char LICENSE[] SEC("license") = "GPL";
+
+Use bpftool to load the BPF program.
+
+::
+
+  bpftool prog load mtd-mchp23k256.o /sys/fs/bpf/mtd_mchp23k256 autoattach
+
+
+This is accomplished by executing the following command:
+
+::
+
+  $ echo mchp23k256 0 > /sys/class/spi_master/spi0/new_device
+
+
+The name of the target driver and its chip select were used to instantiate
+the device.
+
+Now, the mchp23k256 MTD device named /dev/mtd0 has been created successfully.
+
+::
+
+  $ ls /sys/bus/spi/devices/spi0.0/mtd/
+  mtd0  mtd0ro
+
+  $ cat /sys/class/mtd/mtd0/name
+  spi0.0
+
+  $ hexdump /dev/mtd0
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0008000
+
+  $echo aaaa > /dev/mtd0
+
+  $ hexdump /dev/mtd0
+  0000000 6161 6161 000a 0000 0000 0000 0000 0000
+  0000010 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0008000
+
+  $ bpftool map update name regs_mchp23k256 key 0 0 0 0 value 0
+
+  $ hexdump /dev/mtd0
+  0000000 6100 6161 000a 0000 0000 0000 0000 0000
+  0000010 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0008000
+
+Remove the mockup device by executing the following command:
+
+::
+
+  $echo 0 > /sys/class/spi_master/spi0/delete_device
-- 
2.34.1