thr3ads.net - Virtualization - [PATCH v11] i2c: virtio: add a virtio i2c frontend driver [Jul 2021]

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Jie Deng

2021-Jul-01 03:24 UTC

[PATCH v11] i2c: virtio: add a virtio i2c frontend driver

Add an I2C bus driver for virtio para-virtualization.

The controller can be emulated by the backend driver in
any device model software by following the virtio protocol.

The device specification can be found on
https://lists.oasis-open.org/archives/virtio-comment/202101/msg00008.html.

By following the specification, people may implement different
backend drivers to emulate different controllers according to
their needs.

Co-developed-by: Conghui Chen <conghui.chen at intel.com>
Signed-off-by: Conghui Chen <conghui.chen at intel.com>
Signed-off-by: Jie Deng <jie.deng at intel.com>
---
Changes v10 -> v11
	- Remove vi->adap.class = I2C_CLASS_DEPRECATED.
	- Use #ifdef CONFIG_PM_SLEEP to replace the "__maybe_unused".
	- Remove "struct mutex lock" in "struct virtio_i2c".
	- Support zero-length request.
	- Remove unnecessary logs.
	- Remove vi->adap.timeout = HZ / 10, just use the default value.
	- Use BIT(0) to define VIRTIO_I2C_FLAGS_FAIL_NEXT.
	- Add the virtio_device index to adapter's naming mechanism.

 drivers/i2c/busses/Kconfig      |  11 ++
 drivers/i2c/busses/Makefile     |   3 +
 drivers/i2c/busses/i2c-virtio.c | 265 ++++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/virtio_i2c.h |  41 +++++++
 include/uapi/linux/virtio_ids.h |   1 +
 5 files changed, 321 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-virtio.c
 create mode 100644 include/uapi/linux/virtio_i2c.h

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 10acece..e47616a 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -21,6 +21,17 @@ config I2C_ALI1535
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-ali1535.
 
+config I2C_VIRTIO
+	tristate "Virtio I2C Adapter"
+	select VIRTIO
+	help
+	  If you say yes to this option, support will be included for the virtio
+	  I2C adapter driver. The hardware can be emulated by any device model
+	  software according to the virtio protocol.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called i2c-virtio.
+
 config I2C_ALI1563
 	tristate "ALI 1563"
 	depends on PCI
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 69e9963..9843756 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -147,4 +147,7 @@ obj-$(CONFIG_I2C_XGENE_SLIMPRO) += i2c-xgene-slimpro.o
 obj-$(CONFIG_SCx200_ACB)	+= scx200_acb.o
 obj-$(CONFIG_I2C_FSI)		+= i2c-fsi.o
 
+# VIRTIO I2C host controller driver
+obj-$(CONFIG_I2C_VIRTIO)	+= i2c-virtio.o
+
 ccflags-$(CONFIG_I2C_DEBUG_BUS) := -DDEBUG
diff --git a/drivers/i2c/busses/i2c-virtio.c b/drivers/i2c/busses/i2c-virtio.c
new file mode 100644
index 0000000..97dda54
--- /dev/null
+++ b/drivers/i2c/busses/i2c-virtio.c
@@ -0,0 +1,265 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Virtio I2C Bus Driver
+ *
+ * The Virtio I2C Specification:
+ *
https://raw.githubusercontent.com/oasis-tcs/virtio-spec/master/virtio-i2c.tex
+ *
+ * Copyright (c) 2021 Intel Corporation. All rights reserved.
+ */
+
+#include <linux/acpi.h>
+#include <linux/completion.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/virtio.h>
+#include <linux/virtio_ids.h>
+#include <linux/virtio_config.h>
+#include <linux/virtio_i2c.h>
+
+/**
+ * struct virtio_i2c - virtio I2C data
+ * @vdev: virtio device for this controller
+ * @completion: completion of virtio I2C message
+ * @adap: I2C adapter for this controller
+ * @vq: the virtio virtqueue for communication
+ */
+struct virtio_i2c {
+	struct virtio_device *vdev;
+	struct completion completion;
+	struct i2c_adapter adap;
+	struct virtqueue *vq;
+};
+
+/**
+ * struct virtio_i2c_req - the virtio I2C request structure
+ * @out_hdr: the OUT header of the virtio I2C message
+ * @buf: the buffer into which data is read, or from which it's written
+ * @in_hdr: the IN header of the virtio I2C message
+ */
+struct virtio_i2c_req {
+	struct virtio_i2c_out_hdr out_hdr	____cacheline_aligned;
+	uint8_t *buf				____cacheline_aligned;
+	struct virtio_i2c_in_hdr in_hdr		____cacheline_aligned;
+};
+
+static void virtio_i2c_msg_done(struct virtqueue *vq)
+{
+	struct virtio_i2c *vi = vq->vdev->priv;
+
+	complete(&vi->completion);
+}
+
+static int virtio_i2c_send_reqs(struct virtqueue *vq,
+				struct virtio_i2c_req *reqs,
+				struct i2c_msg *msgs, int nr)
+{
+	struct scatterlist *sgs[3], out_hdr, msg_buf, in_hdr;
+	int i, outcnt, incnt, err = 0;
+
+	for (i = 0; i < nr; i++) {
+		/*
+		 * Only 7-bit mode supported for this moment. For the address format,
+		 * Please check the Virtio I2C Specification.
+		 */
+		reqs[i].out_hdr.addr = cpu_to_le16(msgs[i].addr << 1);
+
+		if (i != nr - 1)
+			reqs[i].out_hdr.flags = cpu_to_le32(VIRTIO_I2C_FLAGS_FAIL_NEXT);
+
+		outcnt = incnt = 0;
+		sg_init_one(&out_hdr, &reqs[i].out_hdr, sizeof(reqs[i].out_hdr));
+		sgs[outcnt++] = &out_hdr;
+
+		reqs[i].buf = i2c_get_dma_safe_msg_buf(&msgs[i], 1);
+		if (!reqs[i].buf)
+			break;
+
+		sg_init_one(&msg_buf, reqs[i].buf, msgs[i].len);
+
+		if (msgs[i].flags & I2C_M_RD)
+			sgs[outcnt + incnt++] = &msg_buf;
+		else
+			sgs[outcnt++] = &msg_buf;
+
+		sg_init_one(&in_hdr, &reqs[i].in_hdr, sizeof(reqs[i].in_hdr));
+		sgs[outcnt + incnt++] = &in_hdr;
+
+		err = virtqueue_add_sgs(vq, sgs, outcnt, incnt, &reqs[i], GFP_KERNEL);
+		if (err < 0) {
+			i2c_put_dma_safe_msg_buf(reqs[i].buf, &msgs[i], false);
+			break;
+		}
+	}
+
+	return i;
+}
+
+static int virtio_i2c_complete_reqs(struct virtqueue *vq,
+				    struct virtio_i2c_req *reqs,
+				    struct i2c_msg *msgs, int nr,
+				    bool timeout)
+{
+	struct virtio_i2c_req *req;
+	bool failed = timeout;
+	unsigned int len;
+	int i, j = 0;
+
+	for (i = 0; i < nr; i++) {
+		/* Detach the ith request from the vq */
+		req = virtqueue_get_buf(vq, &len);
+
+		/*
+		 * Condition (req && req == &reqs[i]) should always meet since
+		 * we have total nr requests in the vq.
+		 */
+		if (!failed && (WARN_ON(!(req && req == &reqs[i])) ||
+		    (req->in_hdr.status != VIRTIO_I2C_MSG_OK)))
+			failed = true;
+
+		i2c_put_dma_safe_msg_buf(reqs[i].buf, &msgs[i], !failed);
+		if (!failed)
+			++j;
+	}
+
+	return (timeout ? -ETIMEDOUT : j);
+}
+
+static int virtio_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int
num)
+{
+	struct virtio_i2c *vi = i2c_get_adapdata(adap);
+	struct virtqueue *vq = vi->vq;
+	struct virtio_i2c_req *reqs;
+	unsigned long time_left;
+	int ret, nr;
+
+	reqs = kcalloc(num, sizeof(*reqs), GFP_KERNEL);
+	if (!reqs)
+		return -ENOMEM;
+
+	ret = virtio_i2c_send_reqs(vq, reqs, msgs, num);
+	if (ret == 0)
+		goto err_free;
+
+	nr = ret;
+	reinit_completion(&vi->completion);
+	virtqueue_kick(vq);
+
+	time_left = wait_for_completion_timeout(&vi->completion,
adap->timeout);
+	if (!time_left)
+		dev_err(&adap->dev, "virtio i2c backend timeout.\n");
+
+	ret = virtio_i2c_complete_reqs(vq, reqs, msgs, nr, !time_left);
+
+err_free:
+	kfree(reqs);
+	return ret;
+}
+
+static void virtio_i2c_del_vqs(struct virtio_device *vdev)
+{
+	vdev->config->reset(vdev);
+	vdev->config->del_vqs(vdev);
+}
+
+static int virtio_i2c_setup_vqs(struct virtio_i2c *vi)
+{
+	struct virtio_device *vdev = vi->vdev;
+
+	vi->vq = virtio_find_single_vq(vdev, virtio_i2c_msg_done, "msg");
+	return PTR_ERR_OR_ZERO(vi->vq);
+}
+
+static u32 virtio_i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static struct i2c_algorithm virtio_algorithm = {
+	.master_xfer = virtio_i2c_xfer,
+	.functionality = virtio_i2c_func,
+};
+
+static int virtio_i2c_probe(struct virtio_device *vdev)
+{
+	struct device *pdev = vdev->dev.parent;
+	struct virtio_i2c *vi;
+	int ret;
+
+	vi = devm_kzalloc(&vdev->dev, sizeof(*vi), GFP_KERNEL);
+	if (!vi)
+		return -ENOMEM;
+
+	vdev->priv = vi;
+	vi->vdev = vdev;
+
+	init_completion(&vi->completion);
+
+	ret = virtio_i2c_setup_vqs(vi);
+	if (ret)
+		return ret;
+
+	vi->adap.owner = THIS_MODULE;
+	snprintf(vi->adap.name, sizeof(vi->adap.name),
+		 "i2c_virtio at virtio bus %d", vdev->index);
+	vi->adap.algo = &virtio_algorithm;
+	vi->adap.dev.parent = &vdev->dev;
+	i2c_set_adapdata(&vi->adap, vi);
+
+	/* Setup ACPI node for controlled devices which will be probed through ACPI */
+	ACPI_COMPANION_SET(&vi->adap.dev, ACPI_COMPANION(pdev));
+
+	ret = i2c_add_adapter(&vi->adap);
+	if (ret)
+		virtio_i2c_del_vqs(vdev);
+
+	return ret;
+}
+
+static void virtio_i2c_remove(struct virtio_device *vdev)
+{
+	struct virtio_i2c *vi = vdev->priv;
+
+	i2c_del_adapter(&vi->adap);
+	virtio_i2c_del_vqs(vdev);
+}
+
+static struct virtio_device_id id_table[] = {
+	{ VIRTIO_ID_I2C_ADAPTER, VIRTIO_DEV_ANY_ID },
+	{}
+};
+MODULE_DEVICE_TABLE(virtio, id_table);
+
+#ifdef CONFIG_PM_SLEEP
+static int virtio_i2c_freeze(struct virtio_device *vdev)
+{
+	virtio_i2c_del_vqs(vdev);
+	return 0;
+}
+
+static int virtio_i2c_restore(struct virtio_device *vdev)
+{
+	return virtio_i2c_setup_vqs(vdev->priv);
+}
+#endif
+
+static struct virtio_driver virtio_i2c_driver = {
+	.id_table	= id_table,
+	.probe		= virtio_i2c_probe,
+	.remove		= virtio_i2c_remove,
+	.driver	= {
+		.name	= "i2c_virtio",
+	},
+#ifdef CONFIG_PM_SLEEP
+	.freeze = virtio_i2c_freeze,
+	.restore = virtio_i2c_restore,
+#endif
+};
+module_virtio_driver(virtio_i2c_driver);
+
+MODULE_AUTHOR("Jie Deng <jie.deng at intel.com>");
+MODULE_AUTHOR("Conghui Chen <conghui.chen at intel.com>");
+MODULE_DESCRIPTION("Virtio i2c bus driver");
+MODULE_LICENSE("GPL");
diff --git a/include/uapi/linux/virtio_i2c.h b/include/uapi/linux/virtio_i2c.h
new file mode 100644
index 0000000..3cc1609
--- /dev/null
+++ b/include/uapi/linux/virtio_i2c.h
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later WITH Linux-syscall-note */
+/*
+ * Definitions for virtio I2C Adpter
+ *
+ * Copyright (c) 2021 Intel Corporation. All rights reserved.
+ */
+
+#ifndef _UAPI_LINUX_VIRTIO_I2C_H
+#define _UAPI_LINUX_VIRTIO_I2C_H
+
+#include <linux/types.h>
+#include <linux/bits.h>
+
+/* The bit 0 of the @virtio_i2c_out_hdr. at flags, used to group the requests
*/
+#define VIRTIO_I2C_FLAGS_FAIL_NEXT	BIT(0)
+
+/**
+ * struct virtio_i2c_out_hdr - the virtio I2C message OUT header
+ * @addr: the controlled device address
+ * @padding: used to pad to full dword
+ * @flags: used for feature extensibility
+ */
+struct virtio_i2c_out_hdr {
+	__le16 addr;
+	__le16 padding;
+	__le32 flags;
+};
+
+/**
+ * struct virtio_i2c_in_hdr - the virtio I2C message IN header
+ * @status: the processing result from the backend
+ */
+struct virtio_i2c_in_hdr {
+	__u8 status;
+};
+
+/* The final status written by the device */
+#define VIRTIO_I2C_MSG_OK	0
+#define VIRTIO_I2C_MSG_ERR	1
+
+#endif /* _UAPI_LINUX_VIRTIO_I2C_H */
diff --git a/include/uapi/linux/virtio_ids.h b/include/uapi/linux/virtio_ids.h
index 4fe842c..3b5f05a 100644
--- a/include/uapi/linux/virtio_ids.h
+++ b/include/uapi/linux/virtio_ids.h
@@ -55,6 +55,7 @@
 #define VIRTIO_ID_FS			26 /* virtio filesystem */
 #define VIRTIO_ID_PMEM			27 /* virtio pmem */
 #define VIRTIO_ID_MAC80211_HWSIM	29 /* virtio mac80211-hwsim */
+#define VIRTIO_ID_I2C_ADAPTER		34 /* virtio i2c adapter */
 #define VIRTIO_ID_BT			40 /* virtio bluetooth */
 
 #endif /* _LINUX_VIRTIO_IDS_H */
-- 
2.7.4

Viresh Kumar

2021-Jul-01 04:04 UTC

head link

[PATCH v11] i2c: virtio: add a virtio i2c frontend driver

On 01-07-21, 11:24, Jie Deng wrote:> Changes v10 -> v11
> 	- Remove vi->adap.class = I2C_CLASS_DEPRECATED.
> 	- Use #ifdef CONFIG_PM_SLEEP to replace the "__maybe_unused".
> 	- Remove "struct mutex lock" in "struct virtio_i2c".
> 	- Support zero-length request.
> 	- Remove unnecessary logs.
> 	- Remove vi->adap.timeout = HZ / 10, just use the default value.
> 	- Use BIT(0) to define VIRTIO_I2C_FLAGS_FAIL_NEXT.
> 	- Add the virtio_device index to adapter's naming mechanism.
Thanks Jie.

I hope you are going to send a fix for specification as well (for the
zero-length request) ?
> diff --git a/drivers/i2c/busses/i2c-virtio.c
b/drivers/i2c/busses/i2c-virtio.c
> +static int virtio_i2c_send_reqs(struct virtqueue *vq,
> +				struct virtio_i2c_req *reqs,
> +				struct i2c_msg *msgs, int nr)
> +{
> +	struct scatterlist *sgs[3], out_hdr, msg_buf, in_hdr;
> +	int i, outcnt, incnt, err = 0;
> +
> +	for (i = 0; i < nr; i++) {
> +		/*
> +		 * Only 7-bit mode supported for this moment. For the address format,
> +		 * Please check the Virtio I2C Specification.
> +		 */
> +		reqs[i].out_hdr.addr = cpu_to_le16(msgs[i].addr << 1);
> +
> +		if (i != nr - 1)
> +			reqs[i].out_hdr.flags = cpu_to_le32(VIRTIO_I2C_FLAGS_FAIL_NEXT);
> +
> +		outcnt = incnt = 0;
> +		sg_init_one(&out_hdr, &reqs[i].out_hdr,
sizeof(reqs[i].out_hdr));
> +		sgs[outcnt++] = &out_hdr;
> +
> +		reqs[i].buf = i2c_get_dma_safe_msg_buf(&msgs[i], 1);
> +		if (!reqs[i].buf)
> +			break;
> +
> +		sg_init_one(&msg_buf, reqs[i].buf, msgs[i].len);
The len can be zero here for zero-length transfers.
> +
> +		if (msgs[i].flags & I2C_M_RD)
> +			sgs[outcnt + incnt++] = &msg_buf;
> +		else
> +			sgs[outcnt++] = &msg_buf;
> +
> +		sg_init_one(&in_hdr, &reqs[i].in_hdr, sizeof(reqs[i].in_hdr));
> +		sgs[outcnt + incnt++] = &in_hdr;
Why are we still sending the msg_buf if the length is 0? Sending the
buffer makes sense if you have some data to send, but otherwise it is
just an extra sg element, which isn't required to be sent.
> +
> +		err = virtqueue_add_sgs(vq, sgs, outcnt, incnt, &reqs[i],
GFP_KERNEL);
> +		if (err < 0) {
> +			i2c_put_dma_safe_msg_buf(reqs[i].buf, &msgs[i], false);
> +			break;
> +		}
> +	}
> +
> +	return i;
I just noticed this now, but this function even tries to send data
partially, which isn't right. If the caller (i2c device's driver)
calls this for 5 struct i2c_msg instances, then all 5 need to get
through or none.. where as we try to send as many as possible here.

This looks broken to me. Rather return an error value here on success,
or make it complete failure.

Though to be fair I see i2c-core also returns number of messages
processed from i2c_transfer().

Wolfram, what's expected here ? Shouldn't all message transfer or
none?
> +#ifdef CONFIG_PM_SLEEP
> +static int virtio_i2c_freeze(struct virtio_device *vdev)
> +{
> +	virtio_i2c_del_vqs(vdev);
> +	return 0;
> +}
> +
> +static int virtio_i2c_restore(struct virtio_device *vdev)
> +{
> +	return virtio_i2c_setup_vqs(vdev->priv);
> +}
> +#endif
> +
> +static struct virtio_driver virtio_i2c_driver = {
> +	.id_table	= id_table,
> +	.probe		= virtio_i2c_probe,
> +	.remove		= virtio_i2c_remove,
> +	.driver	= {
> +		.name	= "i2c_virtio",
> +	},
> +#ifdef CONFIG_PM_SLEEP
You could avoid this pair of ifdef by creating dummy versions of below
routines for !CONFIG_PM_SLEEP case. Up to you.
> +	.freeze = virtio_i2c_freeze,
> +	.restore = virtio_i2c_restore,
> +#endif
> +};
-- 
viresh

kernel test robot

2021-Jul-01 08:50 UTC

head link

[PATCH v11] i2c: virtio: add a virtio i2c frontend driver

Hi Jie,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on wsa/i2c/for-next]
[also build test ERROR on linux/master linus/master v5.13 next-20210630]
[cannot apply to vhost/linux-next]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:   
https://github.com/0day-ci/linux/commits/Jie-Deng/i2c-virtio-add-a-virtio-i2c-frontend-driver/20210701-112619
base:   https://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git
i2c/for-next
config: x86_64-randconfig-r012-20210630 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project
e7e71e9454ed76c1b3d8140170b5333c28bef1be)
reproduce (this is a W=1 build):
        wget
https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O
~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        #
https://github.com/0day-ci/linux/commit/e8dedd2a8577148d7655d0affe35adf34efbbf15
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review
Jie-Deng/i2c-virtio-add-a-virtio-i2c-frontend-driver/20210701-112619
        git checkout e8dedd2a8577148d7655d0affe35adf34efbbf15
        # save the attached .config to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross O=build_dir
ARCH=x86_64 SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp at intel.com>

All errors (new ones prefixed by >>):

   In file included from <built-in>:1:>> ./usr/include/linux/virtio_i2c.h:12:10: fatal error:
'linux/bits.h' file not found   #include <linux/bits.h>
            ^~~~~~~~~~~~~~
   1 error generated.

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all at lists.01.org
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kernel test robot

2021-Jul-01 10:00 UTC

head link

[PATCH v11] i2c: virtio: add a virtio i2c frontend driver

Hi Jie,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on wsa/i2c/for-next]
[also build test ERROR on linux/master linus/master v5.13 next-20210630]
[cannot apply to vhost/linux-next]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:   
https://github.com/0day-ci/linux/commits/Jie-Deng/i2c-virtio-add-a-virtio-i2c-frontend-driver/20210701-112619
base:   https://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git
i2c/for-next
config: i386-randconfig-c021-20210630 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
        #
https://github.com/0day-ci/linux/commit/e8dedd2a8577148d7655d0affe35adf34efbbf15
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review
Jie-Deng/i2c-virtio-add-a-virtio-i2c-frontend-driver/20210701-112619
        git checkout e8dedd2a8577148d7655d0affe35adf34efbbf15
        # save the attached .config to linux build tree
        mkdir build_dir
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp at intel.com>

All errors (new ones prefixed by >>):

   In file included from <command-line>:32:>> ./usr/include/linux/virtio_i2c.h:12:10: fatal error: linux/bits.h: No
such file or directory      12 | #include <linux/bits.h>
         |          ^~~~~~~~~~~~~~
   compilation terminated.

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all at lists.01.org
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Andy Shevchenko

2021-Jul-01 10:45 UTC

head link

[PATCH v11] i2c: virtio: add a virtio i2c frontend driver

On Thu, Jul 01, 2021 at 11:24:46AM +0800, Jie Deng
wrote:> Add an I2C bus driver for virtio para-virtualization.
> 
> The controller can be emulated by the backend driver in
> any device model software by following the virtio protocol.
> 
> The device specification can be found on
> https://lists.oasis-open.org/archives/virtio-comment/202101/msg00008.html.
> 
> By following the specification, people may implement different
> backend drivers to emulate different controllers according to
> their needs.
> 	- Use #ifdef CONFIG_PM_SLEEP to replace the "__maybe_unused".
Why is that?

-- 
With Best Regards,
Andy Shevchenko

Virtualization - Jul 2021 - [PATCH v11] i2c: virtio: add a virtio i2c frontend driver

[PATCH v11] i2c: virtio: add a virtio i2c frontend driver

[PATCH v11] i2c: virtio: add a virtio i2c frontend driver

[PATCH v11] i2c: virtio: add a virtio i2c frontend driver

[PATCH v11] i2c: virtio: add a virtio i2c frontend driver

[PATCH v11] i2c: virtio: add a virtio i2c frontend driver