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>
---
drivers/i2c/busses/Kconfig | 11 ++
drivers/i2c/busses/Makefile | 3 +
drivers/i2c/busses/i2c-virtio.c | 289 ++++++++++++++++++++++++++++++++++++++++
include/uapi/linux/virtio_i2c.h | 42 ++++++
include/uapi/linux/virtio_ids.h | 1 +
5 files changed, 346 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 05ebf75..0860395 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"
+ depends on 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 615f35e..b88da08 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -6,6 +6,9 @@
# ACPI drivers
obj-$(CONFIG_I2C_SCMI) += i2c-scmi.o
+# VIRTIO I2C host controller driver
+obj-$(CONFIG_I2C_VIRTIO) += i2c-virtio.o
+
# PC SMBus host controller drivers
obj-$(CONFIG_I2C_ALI1535) += i2c-ali1535.o
obj-$(CONFIG_I2C_ALI1563) += i2c-ali1563.o
diff --git a/drivers/i2c/busses/i2c-virtio.c b/drivers/i2c/busses/i2c-virtio.c
new file mode 100644
index 0000000..98c0fcc
--- /dev/null
+++ b/drivers/i2c/busses/i2c-virtio.c
@@ -0,0 +1,289 @@
+// 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/io.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/wait.h>
+
+#include <linux/virtio.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
+ * @i2c_lock: lock for virtqueue processing
+ * @vq: the virtio virtqueue for communication
+ */
+struct virtio_i2c {
+ struct virtio_device *vdev;
+ struct completion completion;
+ struct i2c_adapter adap;
+ struct mutex i2c_lock;
+ 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;
+ u8 *buf;
+ struct virtio_i2c_in_hdr in_hdr;
+};
+
+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;
+ u8 *buf;
+
+ for (i = 0; i < nr; i++) {
+ if (!msgs[i].len)
+ break;
+
+ /* 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 |= 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;
+
+ buf = kzalloc(msgs[i].len, GFP_KERNEL);
+ if (!buf)
+ break;
+
+ reqs[i].buf = buf;
+ sg_init_one(&msg_buf, reqs[i].buf, msgs[i].len);
+
+ if (msgs[i].flags & I2C_M_RD) {
+ sgs[outcnt + incnt++] = &msg_buf;
+ } else {
+ memcpy(reqs[i].buf, msgs[i].buf, msgs[i].len);
+ 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) {
+ pr_err("failed to add msg[%d] to virtqueue.\n", i);
+ kfree(reqs[i].buf);
+ reqs[i].buf = NULL;
+ break;
+ }
+ }
+
+ return i;
+}
+
+static int virtio_i2c_complete_reqs(struct virtqueue *vq,
+ struct virtio_i2c_req *reqs,
+ struct i2c_msg *msgs, int nr)
+{
+ struct virtio_i2c_req *req;
+ unsigned int len;
+ int i;
+
+ for (i = 0; i < nr; i++) {
+ req = (struct virtio_i2c_req *)virtqueue_get_buf(vq, &len);
+ if (!(req && req == &reqs[i])) {
+ pr_err("msg[%d]: addr=0x%x virtqueue error.\n", i, msgs[i].addr);
+ break;
+ }
+
+ if (req->in_hdr.status != VIRTIO_I2C_MSG_OK) {
+ pr_err("msg[%d]: addr=0x%x backend error.\n", i, msgs[i].addr);
+ break;
+ }
+
+ if (msgs[i].flags & I2C_M_RD)
+ memcpy(msgs[i].buf, req->buf, msgs[i].len);
+
+ kfree(req->buf);
+ req->buf = NULL;
+ }
+
+ return i;
+}
+
+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;
+
+ mutex_lock(&vi->i2c_lock);
+
+ ret = virtio_i2c_send_reqs(vq, reqs, msgs, num);
+ if (ret == 0)
+ goto err_unlock_free;
+
+ nr = ret;
+
+ 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 = -ETIMEDOUT;
+ goto err_unlock_free;
+ }
+
+ ret = virtio_i2c_complete_reqs(vq, reqs, msgs, nr);
+
+ reinit_completion(&vi->completion);
+
+err_unlock_free:
+ mutex_unlock(&vi->i2c_lock);
+ 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 struct i2c_adapter virtio_adapter = {
+ .owner = THIS_MODULE,
+ .name = "Virtio I2C Adapter",
+ .class = I2C_CLASS_DEPRECATED,
+ .algo = &virtio_algorithm,
+};
+
+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;
+
+ mutex_init(&vi->i2c_lock);
+ init_completion(&vi->completion);
+
+ ret = virtio_i2c_setup_vqs(vi);
+ if (ret)
+ return ret;
+
+ vi->adap = virtio_adapter;
+ i2c_set_adapdata(&vi->adap, vi);
+ vi->adap.dev.parent = &vdev->dev;
+ /* Setup ACPI node for controlled devices which will be probed through ACPI */
+ ACPI_COMPANION_SET(&vi->adap.dev, ACPI_COMPANION(pdev));
+ vi->adap.timeout = HZ / 10;
+
+ ret = i2c_add_adapter(&vi->adap);
+ if (ret) {
+ virtio_i2c_del_vqs(vdev);
+ dev_err(&vdev->dev, "failed to add virtio-i2c adapter.\n");
+ }
+
+ 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_ADPTER, VIRTIO_DEV_ANY_ID },
+ {}
+};
+MODULE_DEVICE_TABLE(virtio, id_table);
+
+static int __maybe_unused virtio_i2c_freeze(struct virtio_device *vdev)
+{
+ virtio_i2c_del_vqs(vdev);
+ return 0;
+}
+
+static int __maybe_unused virtio_i2c_restore(struct virtio_device *vdev)
+{
+ return virtio_i2c_setup_vqs(vdev->priv);
+}
+
+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_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..00f4508
--- /dev/null
+++ b/include/uapi/linux/virtio_i2c.h
@@ -0,0 +1,42 @@
+/* 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/virtio_ids.h>
+#include <linux/virtio_config.h>
+
+/**
+ * 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;
+};
+
+/* The bit 0 of the @virtio_i2c_out_hdr. at flags, used to group the requests
*/
+#define VIRTIO_I2C_FLAGS_FAIL_NEXT 0x00000001
+
+/**
+ * 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 bc1c062..6ae32db 100644
--- a/include/uapi/linux/virtio_ids.h
+++ b/include/uapi/linux/virtio_ids.h
@@ -54,5 +54,6 @@
#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_ADPTER 34 /* virtio i2c adpter */
#endif /* _LINUX_VIRTIO_IDS_H */
--
2.7.4
kernel test robot
2021-Mar-04 05:37 UTC
[PATCH v6] 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 vhost/linux-next linux/master linus/master v5.12-rc1
next-20210303]
[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/20210304-100543
base: https://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git
i2c/for-next
config: i386-randconfig-a006-20210304 (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/bb645653b6d7750a026229726f8d9d0371457ac6
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/20210304-100543
git checkout bb645653b6d7750a026229726f8d9d0371457ac6
# save the attached .config to linux build tree
make W=1 ARCH=i386
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:35:2: error: unknown type name
'u8'
35 | u8 status;
| ^~
---
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-Mar-04 05:40 UTC
[PATCH v6] i2c: virtio: add a virtio i2c frontend driver
Hi Jie,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on wsa/i2c/for-next]
[also build test WARNING on vhost/linux-next linux/master linus/master v5.12-rc1
next-20210303]
[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/20210304-100543
base: https://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git
i2c/for-next
config: xtensa-randconfig-s031-20210304 (attached as .config)
compiler: xtensa-linux-gcc (GCC) 9.3.0
reproduce:
wget
https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O
~/bin/make.cross
chmod +x ~/bin/make.cross
# apt-get install sparse
# sparse version: v0.6.3-245-gacc5c298-dirty
#
https://github.com/0day-ci/linux/commit/bb645653b6d7750a026229726f8d9d0371457ac6
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/20210304-100543
git checkout bb645653b6d7750a026229726f8d9d0371457ac6
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross C=1
CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=xtensa
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp at intel.com>
"sparse warnings: (new ones prefixed by
>>)">> drivers/i2c/busses/i2c-virtio.c:78:47: sparse: sparse: invalid
assignment: |>> drivers/i2c/busses/i2c-virtio.c:78:47: sparse: left
side has type restricted __le32
>> drivers/i2c/busses/i2c-virtio.c:78:47: sparse: right side has type
int
vim +78 drivers/i2c/busses/i2c-virtio.c
59
60 static int virtio_i2c_send_reqs(struct virtqueue *vq,
61 struct virtio_i2c_req *reqs,
62 struct i2c_msg *msgs, int nr)
63 {
64 struct scatterlist *sgs[3], out_hdr, msg_buf, in_hdr;
65 int i, outcnt, incnt, err = 0;
66 u8 *buf;
67
68 for (i = 0; i < nr; i++) {
69 if (!msgs[i].len)
70 break;
71
72 /* Only 7-bit mode supported for this moment. For the address format,
73 * Please check the Virtio I2C Specification.
74 */
75 reqs[i].out_hdr.addr = cpu_to_le16(msgs[i].addr << 1);
76
77 if (i != nr - 1)
> 78 reqs[i].out_hdr.flags |= VIRTIO_I2C_FLAGS_FAIL_NEXT;
79
80 outcnt = incnt = 0;
81 sg_init_one(&out_hdr, &reqs[i].out_hdr,
sizeof(reqs[i].out_hdr));
82 sgs[outcnt++] = &out_hdr;
83
84 buf = kzalloc(msgs[i].len, GFP_KERNEL);
85 if (!buf)
86 break;
87
88 reqs[i].buf = buf;
89 sg_init_one(&msg_buf, reqs[i].buf, msgs[i].len);
90
91 if (msgs[i].flags & I2C_M_RD) {
92 sgs[outcnt + incnt++] = &msg_buf;
93 } else {
94 memcpy(reqs[i].buf, msgs[i].buf, msgs[i].len);
95 sgs[outcnt++] = &msg_buf;
96 }
97
98 sg_init_one(&in_hdr, &reqs[i].in_hdr, sizeof(reqs[i].in_hdr));
99 sgs[outcnt + incnt++] = &in_hdr;
100
101 err = virtqueue_add_sgs(vq, sgs, outcnt, incnt, &reqs[i],
GFP_KERNEL);
102 if (err < 0) {
103 pr_err("failed to add msg[%d] to virtqueue.\n", i);
104 kfree(reqs[i].buf);
105 reqs[i].buf = NULL;
106 break;
107 }
108 }
109
110 return i;
111 }
112
---
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-Mar-04 06:22 UTC
[PATCH v6] 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 vhost/linux-next linux/master linus/master v5.12-rc1
next-20210303]
[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/20210304-100543
base: https://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git
i2c/for-next
config: x86_64-randconfig-a014-20210304 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project
eec7f8f7b1226be422a76542cb403d02538f453a)
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/bb645653b6d7750a026229726f8d9d0371457ac6
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/20210304-100543
git checkout bb645653b6d7750a026229726f8d9d0371457ac6
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64
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:35:2: error: unknown type name
'u8'
u8 status;
^
1 error generated.
---
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On 2021/3/4 9:59 ??, 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. > > 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> > --- > drivers/i2c/busses/Kconfig | 11 ++ > drivers/i2c/busses/Makefile | 3 + > drivers/i2c/busses/i2c-virtio.c | 289 ++++++++++++++++++++++++++++++++++++++++ > include/uapi/linux/virtio_i2c.h | 42 ++++++ > include/uapi/linux/virtio_ids.h | 1 + > 5 files changed, 346 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 05ebf75..0860395 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" > + depends on VIRTIOPlease use select here. There's no prompt for 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 615f35e..b88da08 100644 > --- a/drivers/i2c/busses/Makefile > +++ b/drivers/i2c/busses/Makefile > @@ -6,6 +6,9 @@ > # ACPI drivers > obj-$(CONFIG_I2C_SCMI) += i2c-scmi.o > > +# VIRTIO I2C host controller driver > +obj-$(CONFIG_I2C_VIRTIO) += i2c-virtio.o > + > # PC SMBus host controller drivers > obj-$(CONFIG_I2C_ALI1535) += i2c-ali1535.o > obj-$(CONFIG_I2C_ALI1563) += i2c-ali1563.o > diff --git a/drivers/i2c/busses/i2c-virtio.c b/drivers/i2c/busses/i2c-virtio.c > new file mode 100644 > index 0000000..98c0fcc > --- /dev/null > +++ b/drivers/i2c/busses/i2c-virtio.c > @@ -0,0 +1,289 @@ > +// 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/io.h> > +#include <linux/jiffies.h> > +#include <linux/kernel.h> > +#include <linux/module.h> > +#include <linux/platform_device.h> > +#include <linux/wait.h> > + > +#include <linux/virtio.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 > + * @i2c_lock: lock for virtqueue processing > + * @vq: the virtio virtqueue for communication > + */ > +struct virtio_i2c { > + struct virtio_device *vdev; > + struct completion completion; > + struct i2c_adapter adap; > + struct mutex i2c_lock; > + 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; > + u8 *buf; > + struct virtio_i2c_in_hdr in_hdr; > +}; > + > +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; > + u8 *buf; > + > + for (i = 0; i < nr; i++) { > + if (!msgs[i].len) > + break; > + > + /* 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 |= 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; > + > + buf = kzalloc(msgs[i].len, GFP_KERNEL); > + if (!buf) > + break; > + > + reqs[i].buf = buf; > + sg_init_one(&msg_buf, reqs[i].buf, msgs[i].len); > + > + if (msgs[i].flags & I2C_M_RD) { > + sgs[outcnt + incnt++] = &msg_buf; > + } else { > + memcpy(reqs[i].buf, msgs[i].buf, msgs[i].len); > + 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) { > + pr_err("failed to add msg[%d] to virtqueue.\n", i); > + kfree(reqs[i].buf); > + reqs[i].buf = NULL; > + break; > + } > + } > + > + return i; > +} > + > +static int virtio_i2c_complete_reqs(struct virtqueue *vq, > + struct virtio_i2c_req *reqs, > + struct i2c_msg *msgs, int nr) > +{ > + struct virtio_i2c_req *req; > + unsigned int len; > + int i; > + > + for (i = 0; i < nr; i++) { > + req = (struct virtio_i2c_req *)virtqueue_get_buf(vq, &len);The case is unnecessary.> + if (!(req && req == &reqs[i])) { > + pr_err("msg[%d]: addr=0x%x virtqueue error.\n", i, msgs[i].addr); > + break; > + }It's better to be more specific here, e.g we can say we saw out of order completion here.> + > + if (req->in_hdr.status != VIRTIO_I2C_MSG_OK) { > + pr_err("msg[%d]: addr=0x%x backend error.\n", i, msgs[i].addr); > + break;Don't we need to clean used ring by keeping calling virtqueue_get_buf() here?> + } > + > + if (msgs[i].flags & I2C_M_RD) > + memcpy(msgs[i].buf, req->buf, msgs[i].len);Sorry if I had asked this before but any rason not to use msg[i].buf directly?> + > + kfree(req->buf); > + req->buf = NULL; > + } > + > + return i; > +} > + > +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; > + > + mutex_lock(&vi->i2c_lock); > + > + ret = virtio_i2c_send_reqs(vq, reqs, msgs, num); > + if (ret == 0) > + goto err_unlock_free; > + > + nr = ret; > + > + 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 = -ETIMEDOUT; > + goto err_unlock_free;So if the request is finished after the timerout, all the following request will fail, is this expected?> + } > + > + ret = virtio_i2c_complete_reqs(vq, reqs, msgs, nr);So consider driver queue N requests, can device raise interrupt if it completes the first request? If yes, the code break, if not it need to be clarified in the spec. Acaultly I remember there's no VIRTIO_I2C_FLAGS_FAIL_NEXT in previous versions, and after reading the spec I still don't get the motivation for that (it may complicates both driver and device actually).> + > + reinit_completion(&vi->completion);So if a request it timeout but interrupt is raised here, everything is broken. Thanks> + > +err_unlock_free: > + mutex_unlock(&vi->i2c_lock); > + 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 struct i2c_adapter virtio_adapter = { > + .owner = THIS_MODULE, > + .name = "Virtio I2C Adapter", > + .class = I2C_CLASS_DEPRECATED, > + .algo = &virtio_algorithm, > +}; > + > +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; > + > + mutex_init(&vi->i2c_lock); > + init_completion(&vi->completion); > + > + ret = virtio_i2c_setup_vqs(vi); > + if (ret) > + return ret; > + > + vi->adap = virtio_adapter; > + i2c_set_adapdata(&vi->adap, vi); > + vi->adap.dev.parent = &vdev->dev; > + /* Setup ACPI node for controlled devices which will be probed through ACPI */ > + ACPI_COMPANION_SET(&vi->adap.dev, ACPI_COMPANION(pdev)); > + vi->adap.timeout = HZ / 10; > + > + ret = i2c_add_adapter(&vi->adap); > + if (ret) { > + virtio_i2c_del_vqs(vdev); > + dev_err(&vdev->dev, "failed to add virtio-i2c adapter.\n"); > + } > + > + 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_ADPTER, VIRTIO_DEV_ANY_ID }, > + {} > +}; > +MODULE_DEVICE_TABLE(virtio, id_table); > + > +static int __maybe_unused virtio_i2c_freeze(struct virtio_device *vdev) > +{ > + virtio_i2c_del_vqs(vdev); > + return 0; > +} > + > +static int __maybe_unused virtio_i2c_restore(struct virtio_device *vdev) > +{ > + return virtio_i2c_setup_vqs(vdev->priv); > +} > + > +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_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..00f4508 > --- /dev/null > +++ b/include/uapi/linux/virtio_i2c.h > @@ -0,0 +1,42 @@ > +/* 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/virtio_ids.h> > +#include <linux/virtio_config.h> > + > +/** > + * 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; > +}; > + > +/* The bit 0 of the @virtio_i2c_out_hdr. at flags, used to group the requests */ > +#define VIRTIO_I2C_FLAGS_FAIL_NEXT 0x00000001 > + > +/** > + * 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 bc1c062..6ae32db 100644 > --- a/include/uapi/linux/virtio_ids.h > +++ b/include/uapi/linux/virtio_ids.h > @@ -54,5 +54,6 @@ > #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_ADPTER 34 /* virtio i2c adpter */ > > #endif /* _LINUX_VIRTIO_IDS_H */