[PATCH v5 0/3] Add MCTP-over-KCS transport binding

[PATCH v5 0/3] Add MCTP-over-KCS transport binding

[Konstantin Aladyshev]

This change adds a MCTP KCS transport binding, as defined by the DMTF
specificiation DSP0254 - "MCTP KCS Transport Binding".
A MCTP protocol network device is created for each KCS channel found in
the system.
The interrupt code for the KCS state machine is based on the current
IPMI KCS driver.
Since the KCS subsystem code is now used both in IPMI and MCTP drivers
the separate patchsets move KCS subsystem includes to a common folder.

Tested:
PLDM communication between the HOST and BMC was tested with both
components implemented via open-source software:
- The HOST (UEFI firmware) part was based one the edk2 [1] and
edk2-platforms [2] code,
- The BMC part was based on the openbmc [3] distribution.

The testing process and all the necessary utilities are described in
the [4] repository.

[1]: https://github.com/tianocore/edk2
[2]: https://github.com/tianocore/edk2-platforms
[3]: https://github.com/openbmc/openbmc
[4]: https://github.com/Kostr/PLDM

Changes v4 -> v5:
 - correct spelling errors in description
 - check that rx data is big enough for binding structures
 - use unsigned int type for index and len variables
 - refactor mctp_kcs_rx_work() function
 - arrange local variables in reverse xmas tree order

Changes v3 -> v4:
 - drop 'inline' keyword

Changes v2 -> v3:
 - use 'dev_err_probe' correctly

Changes v1 -> v2:
 - correct warning found by kernel test robot
 - use 'i2c_smbus_pec' library function for PEC calculation
 - several code style corrections based on Jonathan Cameron comments
Original patchset can be found here:
https://lwn.net/ml/linux-kernel/20230928123009.2913-1-aladyshev22@gmail.com/


Konstantin Aladyshev (3):
  ipmi: Move KCS headers to common include folder
  ipmi: Create header with KCS interface defines
  mctp: Add MCTP-over-KCS transport binding

 drivers/char/ipmi/kcs_bmc.c                   |   8 +-
 drivers/char/ipmi/kcs_bmc_aspeed.c            |   3 +-
 drivers/char/ipmi/kcs_bmc_cdev_ipmi.c         |  73 +--
 drivers/char/ipmi/kcs_bmc_npcm7xx.c           |   2 +-
 drivers/char/ipmi/kcs_bmc_serio.c             |   2 +-
 drivers/net/mctp/Kconfig                      |   8 +
 drivers/net/mctp/Makefile                     |   1 +
 drivers/net/mctp/mctp-kcs.c                   | 600 ++++++++++++++++++
 include/linux/ipmi_kcs.h                      |  80 +++
 .../char/ipmi => include/linux}/kcs_bmc.h     |   0
 .../ipmi => include/linux}/kcs_bmc_client.h   |   3 +-
 .../ipmi => include/linux}/kcs_bmc_device.h   |   3 +-
 12 files changed, 699 insertions(+), 84 deletions(-)
 create mode 100644 drivers/net/mctp/mctp-kcs.c
 create mode 100644 include/linux/ipmi_kcs.h
 rename {drivers/char/ipmi => include/linux}/kcs_bmc.h (100%)
 rename {drivers/char/ipmi => include/linux}/kcs_bmc_client.h (97%)
 rename {drivers/char/ipmi => include/linux}/kcs_bmc_device.h (96%)

-- 
2.25.1

[PATCH v5 1/3] ipmi: Move KCS headers to common include folder

[Konstantin Aladyshev]

The current KCS header files can be utilized by both IPMI drivers
(drivers/char/ipmi) and MCTP driver (drivers/net/mctp). To be able to
use them in both cases move the headers to 'include/linux' folder.

Signed-off-by: Konstantin Aladyshev <aladyshev22@gmail.com>
---
 drivers/char/ipmi/kcs_bmc.c                           | 8 +++-----
 drivers/char/ipmi/kcs_bmc_aspeed.c                    | 3 +--
 drivers/char/ipmi/kcs_bmc_cdev_ipmi.c                 | 2 +-
 drivers/char/ipmi/kcs_bmc_npcm7xx.c                   | 2 +-
 drivers/char/ipmi/kcs_bmc_serio.c                     | 2 +-
 {drivers/char/ipmi => include/linux}/kcs_bmc.h        | 0
 {drivers/char/ipmi => include/linux}/kcs_bmc_client.h | 3 +--
 {drivers/char/ipmi => include/linux}/kcs_bmc_device.h | 3 +--
 8 files changed, 9 insertions(+), 14 deletions(-)
 rename {drivers/char/ipmi => include/linux}/kcs_bmc.h (100%)
 rename {drivers/char/ipmi => include/linux}/kcs_bmc_client.h (97%)
 rename {drivers/char/ipmi => include/linux}/kcs_bmc_device.h (96%)

diff --git a/drivers/char/ipmi/kcs_bmc.c b/drivers/char/ipmi/kcs_bmc.c
index 8b1161d5194a..d29a8505d6ed 100644
--- a/drivers/char/ipmi/kcs_bmc.c
+++ b/drivers/char/ipmi/kcs_bmc.c
@@ -5,15 +5,13 @@
  */
 
 #include <linux/device.h>
+#include <linux/kcs_bmc.h>
+#include <linux/kcs_bmc_client.h>
+#include <linux/kcs_bmc_device.h>
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 
-#include "kcs_bmc.h"
-
-/* Implement both the device and client interfaces here */
-#include "kcs_bmc_device.h"
-#include "kcs_bmc_client.h"
 
 /* Record registered devices and drivers */
 static DEFINE_MUTEX(kcs_bmc_lock);
diff --git a/drivers/char/ipmi/kcs_bmc_aspeed.c b/drivers/char/ipmi/kcs_bmc_aspeed.c
index 72640da55380..3dc0dfb448f5 100644
--- a/drivers/char/ipmi/kcs_bmc_aspeed.c
+++ b/drivers/char/ipmi/kcs_bmc_aspeed.c
@@ -10,6 +10,7 @@
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/irq.h>
+#include <linux/kcs_bmc_device.h>
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of.h>
@@ -21,8 +22,6 @@
 #include <linux/slab.h>
 #include <linux/timer.h>
 
-#include "kcs_bmc_device.h"
-
 
 #define DEVICE_NAME     "ast-kcs-bmc"
 
diff --git a/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c b/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c
index cf670e891966..bf1001130a6c 100644
--- a/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c
+++ b/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c
@@ -8,6 +8,7 @@
 #include <linux/errno.h>
 #include <linux/io.h>
 #include <linux/ipmi_bmc.h>
+#include <linux/kcs_bmc_client.h>
 #include <linux/list.h>
 #include <linux/miscdevice.h>
 #include <linux/module.h>
@@ -17,7 +18,6 @@
 #include <linux/sched.h>
 #include <linux/slab.h>
 
-#include "kcs_bmc_client.h"
 
 /* Different phases of the KCS BMC module.
  *  KCS_PHASE_IDLE:
diff --git a/drivers/char/ipmi/kcs_bmc_npcm7xx.c b/drivers/char/ipmi/kcs_bmc_npcm7xx.c
index 7961fec56476..160553248a93 100644
--- a/drivers/char/ipmi/kcs_bmc_npcm7xx.c
+++ b/drivers/char/ipmi/kcs_bmc_npcm7xx.c
@@ -10,6 +10,7 @@
 #include <linux/errno.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
+#include <linux/kcs_bmc_device.h>
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of.h>
@@ -17,7 +18,6 @@
 #include <linux/regmap.h>
 #include <linux/slab.h>
 
-#include "kcs_bmc_device.h"
 
 #define DEVICE_NAME	"npcm-kcs-bmc"
 #define KCS_CHANNEL_MAX	3
diff --git a/drivers/char/ipmi/kcs_bmc_serio.c b/drivers/char/ipmi/kcs_bmc_serio.c
index 1793358be782..24df7144a189 100644
--- a/drivers/char/ipmi/kcs_bmc_serio.c
+++ b/drivers/char/ipmi/kcs_bmc_serio.c
@@ -5,12 +5,12 @@
 #include <linux/device.h>
 #include <linux/errno.h>
 #include <linux/list.h>
+#include <linux/kcs_bmc_client.h>
 #include <linux/module.h>
 #include <linux/sched/signal.h>
 #include <linux/serio.h>
 #include <linux/slab.h>
 
-#include "kcs_bmc_client.h"
 
 struct kcs_bmc_serio {
 	struct list_head entry;
diff --git a/drivers/char/ipmi/kcs_bmc.h b/include/linux/kcs_bmc.h
similarity index 100%
rename from drivers/char/ipmi/kcs_bmc.h
rename to include/linux/kcs_bmc.h
diff --git a/drivers/char/ipmi/kcs_bmc_client.h b/include/linux/kcs_bmc_client.h
similarity index 97%
rename from drivers/char/ipmi/kcs_bmc_client.h
rename to include/linux/kcs_bmc_client.h
index 6fdcde0a7169..f6350c9366dd 100644
--- a/drivers/char/ipmi/kcs_bmc_client.h
+++ b/include/linux/kcs_bmc_client.h
@@ -5,8 +5,7 @@
 #define __KCS_BMC_CONSUMER_H__
 
 #include <linux/irqreturn.h>
-
-#include "kcs_bmc.h"
+#include <linux/kcs_bmc.h>
 
 struct kcs_bmc_driver_ops {
 	int (*add_device)(struct kcs_bmc_device *kcs_bmc);
diff --git a/drivers/char/ipmi/kcs_bmc_device.h b/include/linux/kcs_bmc_device.h
similarity index 96%
rename from drivers/char/ipmi/kcs_bmc_device.h
rename to include/linux/kcs_bmc_device.h
index 17c572f25c54..65333b68c0af 100644
--- a/drivers/char/ipmi/kcs_bmc_device.h
+++ b/include/linux/kcs_bmc_device.h
@@ -5,8 +5,7 @@
 #define __KCS_BMC_DEVICE_H__
 
 #include <linux/irqreturn.h>
-
-#include "kcs_bmc.h"
+#include <linux/kcs_bmc.h>
 
 struct kcs_bmc_device_ops {
 	void (*irq_mask_update)(struct kcs_bmc_device *kcs_bmc, u8 mask, u8 enable);
-- 
2.25.1

Re: [PATCH v5 1/3] ipmi: Move KCS headers to common include folder

[Jonathan Cameron]

On Tue, 10 Oct 2023 15:23:19 +0300
Konstantin Aladyshev <aladyshev22@gmail.com> wrote:

> The current KCS header files can be utilized by both IPMI drivers
> (drivers/char/ipmi) and MCTP driver (drivers/net/mctp). To be able to
> use them in both cases move the headers to 'include/linux' folder.
> 
> Signed-off-by: Konstantin Aladyshev <aladyshev22@gmail.com>
Not particularly important but I wonder if
include/linux/kcs/bmc.h
include/linux/kcs/bmc_client.h
include/linux/kcs/bmc_device.h

might be a cleaner choice given that you are moving them.

I don't care that much though so up to you :)

Jonathan

> ---
>  drivers/char/ipmi/kcs_bmc.c                           | 8 +++-----
>  drivers/char/ipmi/kcs_bmc_aspeed.c                    | 3 +--
>  drivers/char/ipmi/kcs_bmc_cdev_ipmi.c                 | 2 +-
>  drivers/char/ipmi/kcs_bmc_npcm7xx.c                   | 2 +-
>  drivers/char/ipmi/kcs_bmc_serio.c                     | 2 +-
>  {drivers/char/ipmi => include/linux}/kcs_bmc.h        | 0
>  {drivers/char/ipmi => include/linux}/kcs_bmc_client.h | 3 +--
>  {drivers/char/ipmi => include/linux}/kcs_bmc_device.h | 3 +--
>  8 files changed, 9 insertions(+), 14 deletions(-)
>  rename {drivers/char/ipmi => include/linux}/kcs_bmc.h (100%)
>  rename {drivers/char/ipmi => include/linux}/kcs_bmc_client.h (97%)
>  rename {drivers/char/ipmi => include/linux}/kcs_bmc_device.h (96%)
> 
> diff --git a/drivers/char/ipmi/kcs_bmc.c b/drivers/char/ipmi/kcs_bmc.c
> index 8b1161d5194a..d29a8505d6ed 100644
> --- a/drivers/char/ipmi/kcs_bmc.c
> +++ b/drivers/char/ipmi/kcs_bmc.c
> @@ -5,15 +5,13 @@
>   */
>  
>  #include <linux/device.h>
> +#include <linux/kcs_bmc.h>
> +#include <linux/kcs_bmc_client.h>
> +#include <linux/kcs_bmc_device.h>
>  #include <linux/list.h>
>  #include <linux/module.h>
>  #include <linux/mutex.h>
>  
> -#include "kcs_bmc.h"
> -
> -/* Implement both the device and client interfaces here */
> -#include "kcs_bmc_device.h"
> -#include "kcs_bmc_client.h"
>  
>  /* Record registered devices and drivers */
>  static DEFINE_MUTEX(kcs_bmc_lock);
> diff --git a/drivers/char/ipmi/kcs_bmc_aspeed.c b/drivers/char/ipmi/kcs_bmc_aspeed.c
> index 72640da55380..3dc0dfb448f5 100644
> --- a/drivers/char/ipmi/kcs_bmc_aspeed.c
> +++ b/drivers/char/ipmi/kcs_bmc_aspeed.c
> @@ -10,6 +10,7 @@
>  #include <linux/interrupt.h>
>  #include <linux/io.h>
>  #include <linux/irq.h>
> +#include <linux/kcs_bmc_device.h>
>  #include <linux/mfd/syscon.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> @@ -21,8 +22,6 @@
>  #include <linux/slab.h>
>  #include <linux/timer.h>
>  
> -#include "kcs_bmc_device.h"
> -
>  
>  #define DEVICE_NAME     "ast-kcs-bmc"
>  
> diff --git a/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c b/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c
> index cf670e891966..bf1001130a6c 100644
> --- a/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c
> +++ b/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c
> @@ -8,6 +8,7 @@
>  #include <linux/errno.h>
>  #include <linux/io.h>
>  #include <linux/ipmi_bmc.h>
> +#include <linux/kcs_bmc_client.h>
>  #include <linux/list.h>
>  #include <linux/miscdevice.h>
>  #include <linux/module.h>
> @@ -17,7 +18,6 @@
>  #include <linux/sched.h>
>  #include <linux/slab.h>
>  
> -#include "kcs_bmc_client.h"
>  
>  /* Different phases of the KCS BMC module.
>   *  KCS_PHASE_IDLE:
> diff --git a/drivers/char/ipmi/kcs_bmc_npcm7xx.c b/drivers/char/ipmi/kcs_bmc_npcm7xx.c
> index 7961fec56476..160553248a93 100644
> --- a/drivers/char/ipmi/kcs_bmc_npcm7xx.c
> +++ b/drivers/char/ipmi/kcs_bmc_npcm7xx.c
> @@ -10,6 +10,7 @@
>  #include <linux/errno.h>
>  #include <linux/interrupt.h>
>  #include <linux/io.h>
> +#include <linux/kcs_bmc_device.h>
>  #include <linux/mfd/syscon.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> @@ -17,7 +18,6 @@
>  #include <linux/regmap.h>
>  #include <linux/slab.h>
>  
> -#include "kcs_bmc_device.h"
>  
>  #define DEVICE_NAME	"npcm-kcs-bmc"
>  #define KCS_CHANNEL_MAX	3
> diff --git a/drivers/char/ipmi/kcs_bmc_serio.c b/drivers/char/ipmi/kcs_bmc_serio.c
> index 1793358be782..24df7144a189 100644
> --- a/drivers/char/ipmi/kcs_bmc_serio.c
> +++ b/drivers/char/ipmi/kcs_bmc_serio.c
> @@ -5,12 +5,12 @@
>  #include <linux/device.h>
>  #include <linux/errno.h>
>  #include <linux/list.h>
> +#include <linux/kcs_bmc_client.h>
>  #include <linux/module.h>
>  #include <linux/sched/signal.h>
>  #include <linux/serio.h>
>  #include <linux/slab.h>
>  
> -#include "kcs_bmc_client.h"
>  
>  struct kcs_bmc_serio {
>  	struct list_head entry;
> diff --git a/drivers/char/ipmi/kcs_bmc.h b/include/linux/kcs_bmc.h
> similarity index 100%
> rename from drivers/char/ipmi/kcs_bmc.h
> rename to include/linux/kcs_bmc.h
> diff --git a/drivers/char/ipmi/kcs_bmc_client.h b/include/linux/kcs_bmc_client.h
> similarity index 97%
> rename from drivers/char/ipmi/kcs_bmc_client.h
> rename to include/linux/kcs_bmc_client.h
> index 6fdcde0a7169..f6350c9366dd 100644
> --- a/drivers/char/ipmi/kcs_bmc_client.h
> +++ b/include/linux/kcs_bmc_client.h
> @@ -5,8 +5,7 @@
>  #define __KCS_BMC_CONSUMER_H__
>  
>  #include <linux/irqreturn.h>
> -
> -#include "kcs_bmc.h"
> +#include <linux/kcs_bmc.h>
>  
>  struct kcs_bmc_driver_ops {
>  	int (*add_device)(struct kcs_bmc_device *kcs_bmc);
> diff --git a/drivers/char/ipmi/kcs_bmc_device.h b/include/linux/kcs_bmc_device.h
> similarity index 96%
> rename from drivers/char/ipmi/kcs_bmc_device.h
> rename to include/linux/kcs_bmc_device.h
> index 17c572f25c54..65333b68c0af 100644
> --- a/drivers/char/ipmi/kcs_bmc_device.h
> +++ b/include/linux/kcs_bmc_device.h
> @@ -5,8 +5,7 @@
>  #define __KCS_BMC_DEVICE_H__
>  
>  #include <linux/irqreturn.h>
> -
> -#include "kcs_bmc.h"
> +#include <linux/kcs_bmc.h>
>  
>  struct kcs_bmc_device_ops {
>  	void (*irq_mask_update)(struct kcs_bmc_device *kcs_bmc, u8 mask, u8 enable);

Re: [PATCH v5 1/3] ipmi: Move KCS headers to common include folder

[kernel test robot]

Hi Konstantin,

kernel test robot noticed the following build errors:

[auto build test ERROR on cminyard-ipmi/for-next]
[also build test ERROR on linus/master v6.6-rc6 next-20231020]
[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#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Konstantin-Aladyshev/ipmi-Move-KCS-headers-to-common-include-folder/20231010-202425
base:   https://github.com/cminyard/linux-ipmi for-next
patch link:    https://lore.kernel.org/r/20231010122321.823-2-aladyshev22%40gmail.com
patch subject: [PATCH v5 1/3] ipmi: Move KCS headers to common include folder
config: mips-allmodconfig (https://download.01.org/0day-ci/archive/20231022/202310220806.BmOW2atE-lkp@intel.com/config)
compiler: mips-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231022/202310220806.BmOW2atE-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202310220806.BmOW2atE-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from include/linux/kcs_bmc_client.h:8,
                    from drivers/char/ipmi/kcs_bmc_cdev_ipmi.c:11:
>> include/linux/kcs_bmc.h:42:9: error: unknown type name 'spinlock_t'
      42 |         spinlock_t lock;
         |         ^~~~~~~~~~


vim +/spinlock_t +42 include/linux/kcs_bmc.h

faae6e391eda73 drivers/char/ipmi/kcs_bmc.h Andrew Jeffery 2021-06-08  31  
d4e7ac68f771ad drivers/char/ipmi/kcs_bmc.h Andrew Jeffery 2021-06-08  32  struct kcs_bmc_device {
d4e7ac68f771ad drivers/char/ipmi/kcs_bmc.h Andrew Jeffery 2021-06-08  33  	struct list_head entry;
20d60f61c58e8c drivers/char/ipmi/kcs_bmc.h Haiyue Wang    2018-02-02  34  
d4e7ac68f771ad drivers/char/ipmi/kcs_bmc.h Andrew Jeffery 2021-06-08  35  	struct device *dev;
20d60f61c58e8c drivers/char/ipmi/kcs_bmc.h Haiyue Wang    2018-02-02  36  	u32 channel;
20d60f61c58e8c drivers/char/ipmi/kcs_bmc.h Haiyue Wang    2018-02-02  37  
20d60f61c58e8c drivers/char/ipmi/kcs_bmc.h Haiyue Wang    2018-02-02  38  	struct kcs_ioreg ioreg;
20d60f61c58e8c drivers/char/ipmi/kcs_bmc.h Haiyue Wang    2018-02-02  39  
d4e7ac68f771ad drivers/char/ipmi/kcs_bmc.h Andrew Jeffery 2021-06-08  40  	const struct kcs_bmc_device_ops *ops;
20d60f61c58e8c drivers/char/ipmi/kcs_bmc.h Haiyue Wang    2018-02-02  41  
d4e7ac68f771ad drivers/char/ipmi/kcs_bmc.h Andrew Jeffery 2021-06-08 @42  	spinlock_t lock;
d4e7ac68f771ad drivers/char/ipmi/kcs_bmc.h Andrew Jeffery 2021-06-08  43  	struct kcs_bmc_client *client;
20d60f61c58e8c drivers/char/ipmi/kcs_bmc.h Haiyue Wang    2018-02-02  44  };
d4e7ac68f771ad drivers/char/ipmi/kcs_bmc.h Andrew Jeffery 2021-06-08  45  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

[PATCH v5 2/3] ipmi: Create header with KCS interface defines

[Konstantin Aladyshev]

Some definitions from the current kcs_bmc_cdev_ipmi driver can be also
utilized by the MTCP KCS binding driver. Move such definitions to the
common header file.

Signed-off-by: Konstantin Aladyshev <aladyshev22@gmail.com>
---
 drivers/char/ipmi/kcs_bmc_cdev_ipmi.c | 71 +-----------------------
 include/linux/ipmi_kcs.h              | 80 +++++++++++++++++++++++++++
 2 files changed, 81 insertions(+), 70 deletions(-)
 create mode 100644 include/linux/ipmi_kcs.h

diff --git a/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c b/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c
index bf1001130a6c..f158f676114c 100644
--- a/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c
+++ b/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c
@@ -8,6 +8,7 @@
 #include <linux/errno.h>
 #include <linux/io.h>
 #include <linux/ipmi_bmc.h>
+#include <linux/ipmi_kcs.h>
 #include <linux/kcs_bmc_client.h>
 #include <linux/list.h>
 #include <linux/miscdevice.h>
@@ -19,53 +20,6 @@
 #include <linux/slab.h>
 
 
-/* Different phases of the KCS BMC module.
- *  KCS_PHASE_IDLE:
- *            BMC should not be expecting nor sending any data.
- *  KCS_PHASE_WRITE_START:
- *            BMC is receiving a WRITE_START command from system software.
- *  KCS_PHASE_WRITE_DATA:
- *            BMC is receiving a data byte from system software.
- *  KCS_PHASE_WRITE_END_CMD:
- *            BMC is waiting a last data byte from system software.
- *  KCS_PHASE_WRITE_DONE:
- *            BMC has received the whole request from system software.
- *  KCS_PHASE_WAIT_READ:
- *            BMC is waiting the response from the upper IPMI service.
- *  KCS_PHASE_READ:
- *            BMC is transferring the response to system software.
- *  KCS_PHASE_ABORT_ERROR1:
- *            BMC is waiting error status request from system software.
- *  KCS_PHASE_ABORT_ERROR2:
- *            BMC is waiting for idle status afer error from system software.
- *  KCS_PHASE_ERROR:
- *            BMC has detected a protocol violation at the interface level.
- */
-enum kcs_ipmi_phases {
-	KCS_PHASE_IDLE,
-
-	KCS_PHASE_WRITE_START,
-	KCS_PHASE_WRITE_DATA,
-	KCS_PHASE_WRITE_END_CMD,
-	KCS_PHASE_WRITE_DONE,
-
-	KCS_PHASE_WAIT_READ,
-	KCS_PHASE_READ,
-
-	KCS_PHASE_ABORT_ERROR1,
-	KCS_PHASE_ABORT_ERROR2,
-	KCS_PHASE_ERROR
-};
-
-/* IPMI 2.0 - Table 9-4, KCS Interface Status Codes */
-enum kcs_ipmi_errors {
-	KCS_NO_ERROR                = 0x00,
-	KCS_ABORTED_BY_COMMAND      = 0x01,
-	KCS_ILLEGAL_CONTROL_CODE    = 0x02,
-	KCS_LENGTH_ERROR            = 0x06,
-	KCS_UNSPECIFIED_ERROR       = 0xFF
-};
-
 struct kcs_bmc_ipmi {
 	struct list_head entry;
 
@@ -95,29 +49,6 @@ struct kcs_bmc_ipmi {
 
 #define KCS_MSG_BUFSIZ    1000
 
-#define KCS_ZERO_DATA     0
-
-/* IPMI 2.0 - Table 9-1, KCS Interface Status Register Bits */
-#define KCS_STATUS_STATE(state) (state << 6)
-#define KCS_STATUS_STATE_MASK   GENMASK(7, 6)
-#define KCS_STATUS_CMD_DAT      BIT(3)
-#define KCS_STATUS_SMS_ATN      BIT(2)
-#define KCS_STATUS_IBF          BIT(1)
-#define KCS_STATUS_OBF          BIT(0)
-
-/* IPMI 2.0 - Table 9-2, KCS Interface State Bits */
-enum kcs_states {
-	IDLE_STATE  = 0,
-	READ_STATE  = 1,
-	WRITE_STATE = 2,
-	ERROR_STATE = 3,
-};
-
-/* IPMI 2.0 - Table 9-3, KCS Interface Control Codes */
-#define KCS_CMD_GET_STATUS_ABORT  0x60
-#define KCS_CMD_WRITE_START       0x61
-#define KCS_CMD_WRITE_END         0x62
-#define KCS_CMD_READ_BYTE         0x68
 
 static inline void set_state(struct kcs_bmc_ipmi *priv, u8 state)
 {
diff --git a/include/linux/ipmi_kcs.h b/include/linux/ipmi_kcs.h
new file mode 100644
index 000000000000..30c4b6e4d689
--- /dev/null
+++ b/include/linux/ipmi_kcs.h
@@ -0,0 +1,80 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2015-2018, Intel Corporation.
+ */
+
+#ifndef __IPMI_KCS_H__
+#define __IPMI_KCS_H__
+
+/* Different phases of the KCS BMC module.
+ *  KCS_PHASE_IDLE:
+ *            BMC should not be expecting nor sending any data.
+ *  KCS_PHASE_WRITE_START:
+ *            BMC is receiving a WRITE_START command from system software.
+ *  KCS_PHASE_WRITE_DATA:
+ *            BMC is receiving a data byte from system software.
+ *  KCS_PHASE_WRITE_END_CMD:
+ *            BMC is waiting a last data byte from system software.
+ *  KCS_PHASE_WRITE_DONE:
+ *            BMC has received the whole request from system software.
+ *  KCS_PHASE_WAIT_READ:
+ *            BMC is waiting the response from the upper IPMI service.
+ *  KCS_PHASE_READ:
+ *            BMC is transferring the response to system software.
+ *  KCS_PHASE_ABORT_ERROR1:
+ *            BMC is waiting error status request from system software.
+ *  KCS_PHASE_ABORT_ERROR2:
+ *            BMC is waiting for idle status afer error from system software.
+ *  KCS_PHASE_ERROR:
+ *            BMC has detected a protocol violation at the interface level.
+ */
+enum kcs_ipmi_phases {
+	KCS_PHASE_IDLE,
+
+	KCS_PHASE_WRITE_START,
+	KCS_PHASE_WRITE_DATA,
+	KCS_PHASE_WRITE_END_CMD,
+	KCS_PHASE_WRITE_DONE,
+
+	KCS_PHASE_WAIT_READ,
+	KCS_PHASE_READ,
+
+	KCS_PHASE_ABORT_ERROR1,
+	KCS_PHASE_ABORT_ERROR2,
+	KCS_PHASE_ERROR
+};
+
+/* IPMI 2.0 - Table 9-4, KCS Interface Status Codes */
+enum kcs_ipmi_errors {
+	KCS_NO_ERROR                = 0x00,
+	KCS_ABORTED_BY_COMMAND      = 0x01,
+	KCS_ILLEGAL_CONTROL_CODE    = 0x02,
+	KCS_LENGTH_ERROR            = 0x06,
+	KCS_UNSPECIFIED_ERROR       = 0xFF
+};
+
+#define KCS_ZERO_DATA     0
+
+/* IPMI 2.0 - Table 9-1, KCS Interface Status Register Bits */
+#define KCS_STATUS_STATE(state) (state << 6)
+#define KCS_STATUS_STATE_MASK   GENMASK(7, 6)
+#define KCS_STATUS_CMD_DAT      BIT(3)
+#define KCS_STATUS_SMS_ATN      BIT(2)
+#define KCS_STATUS_IBF          BIT(1)
+#define KCS_STATUS_OBF          BIT(0)
+
+/* IPMI 2.0 - Table 9-2, KCS Interface State Bits */
+enum kcs_states {
+	IDLE_STATE  = 0,
+	READ_STATE  = 1,
+	WRITE_STATE = 2,
+	ERROR_STATE = 3,
+};
+
+/* IPMI 2.0 - Table 9-3, KCS Interface Control Codes */
+#define KCS_CMD_GET_STATUS_ABORT  0x60
+#define KCS_CMD_WRITE_START       0x61
+#define KCS_CMD_WRITE_END         0x62
+#define KCS_CMD_READ_BYTE         0x68
+
+#endif /* __IPMI_KCS_H__ */
-- 
2.25.1

[PATCH v5 3/3] mctp: Add MCTP-over-KCS transport binding

[Konstantin Aladyshev]

This change adds a MCTP KCS transport binding, as defined by the DMTF
specification DSP0254 - "MCTP KCS Transport Binding".
A MCTP protocol network device is created for each KCS channel found in
the system.
The interrupt code for the KCS state machine is based on the current
IPMI KCS driver.

Signed-off-by: Konstantin Aladyshev <aladyshev22@gmail.com>
---
 drivers/net/mctp/Kconfig    |   8 +
 drivers/net/mctp/Makefile   |   1 +
 drivers/net/mctp/mctp-kcs.c | 600 ++++++++++++++++++++++++++++++++++++
 3 files changed, 609 insertions(+)
 create mode 100644 drivers/net/mctp/mctp-kcs.c

diff --git a/drivers/net/mctp/Kconfig b/drivers/net/mctp/Kconfig
index dc71657d9184..a37f7ba947c0 100644
--- a/drivers/net/mctp/Kconfig
+++ b/drivers/net/mctp/Kconfig
@@ -33,6 +33,14 @@ config MCTP_TRANSPORT_I2C
 	  from DMTF specification DSP0237. A MCTP protocol network device is
 	  created for each I2C bus that has been assigned a mctp-i2c device.
 
+config MCTP_TRANSPORT_KCS
+	tristate "MCTP KCS transport"
+	depends on IPMI_KCS_BMC
+	help
+	  Provides a driver to access MCTP devices over KCS transport, from
+	  DMTF specification DSP0254. A MCTP protocol network device is
+	  created for each KCS channel found in the system.
+
 endmenu
 
 endif
diff --git a/drivers/net/mctp/Makefile b/drivers/net/mctp/Makefile
index 1ca3e6028f77..885339a40f22 100644
--- a/drivers/net/mctp/Makefile
+++ b/drivers/net/mctp/Makefile
@@ -1,2 +1,3 @@
 obj-$(CONFIG_MCTP_SERIAL) += mctp-serial.o
 obj-$(CONFIG_MCTP_TRANSPORT_I2C) += mctp-i2c.o
+obj-$(CONFIG_MCTP_TRANSPORT_KCS) += mctp-kcs.o
diff --git a/drivers/net/mctp/mctp-kcs.c b/drivers/net/mctp/mctp-kcs.c
new file mode 100644
index 000000000000..b0d903609c64
--- /dev/null
+++ b/drivers/net/mctp/mctp-kcs.c
@@ -0,0 +1,600 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Management Component Transport Protocol (MCTP) KCS transport binding.
+ * This driver is an implementation of the DMTF specification
+ * "DSP0254 - Management Component Transport Protocol (MCTP) KCS Transport
+ * Binding", available at:
+ *
+ * https://www.dmtf.org/sites/default/files/standards/documents/DSP0254_1.0.0.pdf
+ *
+ * This driver provides DSP0254-type MCTP-over-KCS transport using a Linux
+ * KCS client subsystem.
+ *
+ * Copyright (c) 2023 Konstantin Aladyshev <aladyshev22@gmail.com>
+ */
+
+#include <linux/i2c.h>
+#include <linux/if_arp.h>
+#include <linux/ipmi_kcs.h>
+#include <linux/kcs_bmc_client.h>
+#include <linux/mctp.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/netdevice.h>
+#include <net/mctp.h>
+#include <net/mctpdevice.h>
+#include <net/pkt_sched.h>
+
+#define MCTP_KCS_MTU 64
+#define KCS_MSG_BUFSIZ 1000
+
+struct mctp_kcs {
+	struct list_head entry;
+
+	/* protects rx & tx state machines */
+	spinlock_t lock;
+
+	struct kcs_bmc_client client;
+	struct net_device *netdev;
+
+	enum kcs_ipmi_phases phase;
+	enum kcs_ipmi_errors error;
+
+	unsigned int data_in_idx;
+	u8 *data_in;
+
+	unsigned int data_out_idx;
+	unsigned int data_out_len;
+	u8 *data_out;
+
+	struct work_struct rx_work;
+};
+
+struct mctp_kcs_header {
+	u8 netfn_lun;
+	u8 defining_body;
+	u8 len;
+} __packed;
+
+struct mctp_kcs_trailer {
+	u8 pec;
+} __packed;
+
+#define MCTP_KCS_NETFN_LUN 0xb0
+#define DEFINING_BODY_DMTF_PRE_OS_WORKING_GROUP 0x01
+
+static int mctp_kcs_validate_data(struct mctp_kcs *mkcs, u8 *data,
+				  unsigned int len)
+{
+	struct mctp_kcs_header *hdr = (struct mctp_kcs_header *)data;
+	struct net_device *ndev = mkcs->netdev;
+	struct mctp_kcs_trailer *tlr;
+	u8 pec;
+
+	if (len < (sizeof(struct mctp_kcs_header) +
+		   sizeof(struct mctp_kcs_trailer))) {
+		dev_err(mkcs->client.dev->dev,
+			"%s: error! Received data size (%d) is less than binding structs size (%d)",
+			__func__, len,
+			sizeof(struct mctp_kcs_header) +
+				sizeof(struct mctp_kcs_trailer));
+		ndev->stats.rx_length_errors++;
+		return -EINVAL;
+	}
+	if (hdr->netfn_lun != MCTP_KCS_NETFN_LUN) {
+		dev_err(mkcs->client.dev->dev,
+			"%s: KCS binding header error! netfn_lun = 0x%02x, but should be 0x%02x",
+			__func__, hdr->netfn_lun, MCTP_KCS_NETFN_LUN);
+		ndev->stats.rx_dropped++;
+		return -EINVAL;
+	}
+	if (hdr->defining_body != DEFINING_BODY_DMTF_PRE_OS_WORKING_GROUP) {
+		dev_err(mkcs->client.dev->dev,
+			"%s: KCS binding header error! defining_body = 0x%02x, but should be 0x%02x",
+			__func__, hdr->defining_body,
+			DEFINING_BODY_DMTF_PRE_OS_WORKING_GROUP);
+		ndev->stats.rx_dropped++;
+		return -EINVAL;
+	}
+	if (hdr->len != (u8)(len - sizeof(struct mctp_kcs_header) -
+			     sizeof(struct mctp_kcs_trailer))) {
+		dev_err(mkcs->client.dev->dev,
+			"%s: KCS binding header error! len = 0x%02x, but should be 0x%02x",
+			__func__, hdr->len,
+			(u8)(len - sizeof(struct mctp_kcs_header) -
+			     sizeof(struct mctp_kcs_trailer)));
+		ndev->stats.rx_length_errors++;
+		return -EINVAL;
+	}
+
+	pec = i2c_smbus_pec(0, (u8 *)(hdr + 1), hdr->len);
+	tlr = (struct mctp_kcs_trailer *)((u8 *)(hdr + 1) + hdr->len);
+	if (pec != tlr->pec) {
+		dev_err(mkcs->client.dev->dev,
+			"%s: PEC error! Packet value=0x%02x, calculated value=0x%02x",
+			__func__, tlr->pec, pec);
+		ndev->stats.rx_crc_errors++;
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static void mctp_kcs_rx_work(struct work_struct *work)
+{
+	struct mctp_kcs *mkcs = container_of(work, struct mctp_kcs, rx_work);
+	struct mctp_skb_cb *cb;
+	unsigned int data_len;
+	struct sk_buff *skb;
+	unsigned long flags;
+	unsigned int i;
+	int rc;
+
+	spin_lock_irqsave(&mkcs->lock, flags);
+	for (i = 0; i < (mkcs->data_in_idx); i++)
+		dev_dbg(mkcs->client.dev->dev, "%s: data_in[%d]=0x%02x",
+			__func__, i, mkcs->data_in[i]);
+
+	if (mkcs->phase != KCS_PHASE_WRITE_DONE) {
+		dev_err(mkcs->client.dev->dev,
+			"%s: error! Wrong KCS stage at the end of data read (phase=%d)",
+			__func__, mkcs->phase);
+		mkcs->netdev->stats.rx_dropped++;
+		goto unlock_irq;
+	}
+
+	rc = mctp_kcs_validate_data(mkcs, mkcs->data_in, mkcs->data_in_idx);
+	if (rc) {
+		dev_err(mkcs->client.dev->dev,
+			"%s: error! Binding validation failed", __func__);
+		goto unlock_irq;
+	}
+
+	data_len = mkcs->data_in_idx - sizeof(struct mctp_kcs_header) -
+		   sizeof(struct mctp_kcs_trailer);
+
+	skb = netdev_alloc_skb(mkcs->netdev, data_len);
+	if (!skb) {
+		mkcs->netdev->stats.rx_dropped++;
+		goto unlock_irq;
+	}
+
+	skb->protocol = htons(ETH_P_MCTP);
+	skb_put_data(skb, mkcs->data_in + sizeof(struct mctp_kcs_header),
+		     data_len);
+	skb_reset_network_header(skb);
+
+	cb = __mctp_cb(skb);
+	cb->halen = 0;
+
+	netif_rx(skb);
+	mkcs->netdev->stats.rx_packets++;
+	mkcs->netdev->stats.rx_bytes += data_len;
+
+unlock_irq:
+	mkcs->phase = KCS_PHASE_WAIT_READ;
+	mkcs->data_in_idx = 0;
+	spin_unlock_irqrestore(&mkcs->lock, flags);
+}
+
+static netdev_tx_t mctp_kcs_start_xmit(struct sk_buff *skb,
+				       struct net_device *ndev)
+{
+	struct mctp_kcs *mkcs = netdev_priv(ndev);
+	struct mctp_kcs_header *kcs_header;
+	unsigned long flags;
+	int i;
+
+	if (skb->len > MCTP_KCS_MTU) {
+		dev_err(&ndev->dev, "%s: error! skb len is bigger than MTU",
+			__func__);
+		ndev->stats.tx_dropped++;
+		goto out;
+	}
+
+	spin_lock_irqsave(&mkcs->lock, flags);
+	if (mkcs->phase != KCS_PHASE_WAIT_READ) {
+		dev_err(&ndev->dev,
+			"%s: error! Wrong KCS stage at the start of data write (phase=%d)",
+			__func__, mkcs->phase);
+		dev_kfree_skb(skb);
+		spin_unlock_irqrestore(&mkcs->lock, flags);
+		return NETDEV_TX_BUSY;
+	}
+
+	netif_stop_queue(ndev);
+	mkcs->phase = KCS_PHASE_READ;
+	kcs_header = (struct mctp_kcs_header *)mkcs->data_out;
+	kcs_header->netfn_lun = MCTP_KCS_NETFN_LUN;
+	kcs_header->defining_body = DEFINING_BODY_DMTF_PRE_OS_WORKING_GROUP;
+	kcs_header->len = skb->len;
+	skb_copy_bits(skb, 0, kcs_header + 1, skb->len);
+	mkcs->data_out[sizeof(struct mctp_kcs_header) + skb->len] =
+		i2c_smbus_pec(0, (u8 *)(kcs_header + 1), skb->len);
+	mkcs->data_out_idx = 1;
+	mkcs->data_out_len = skb->len + sizeof(struct mctp_kcs_header) +
+			     sizeof(struct mctp_kcs_trailer);
+
+	for (i = 0; i < (mkcs->data_out_len); i++)
+		dev_dbg(&ndev->dev, "%s: data_out[%d]=0x%02x", __func__, i,
+			mkcs->data_out[i]);
+
+	// Write first data byte to initialize transmission
+	kcs_bmc_write_data(mkcs->client.dev, mkcs->data_out[0]);
+
+	spin_unlock_irqrestore(&mkcs->lock, flags);
+out:
+	dev_kfree_skb(skb);
+	return NETDEV_TX_OK;
+}
+
+static void set_state(struct mctp_kcs *mkcs, u8 state)
+{
+	dev_dbg(mkcs->client.dev->dev, "%s: state=0x%02x", __func__, state);
+	kcs_bmc_update_status(mkcs->client.dev, KCS_STATUS_STATE_MASK,
+			      KCS_STATUS_STATE(state));
+}
+
+static int mctp_kcs_ndo_open(struct net_device *ndev)
+{
+	struct mctp_kcs *mkcs;
+
+	mkcs = netdev_priv(ndev);
+	dev_info(&ndev->dev, "Open MCTP over KCS channel %d",
+		 mkcs->client.dev->channel);
+	return kcs_bmc_enable_device(mkcs->client.dev, &mkcs->client);
+}
+
+static int mctp_kcs_ndo_stop(struct net_device *ndev)
+{
+	struct mctp_kcs *mkcs;
+
+	mkcs = netdev_priv(ndev);
+	dev_info(&ndev->dev, "Stop MCTP over KCS channel %d",
+		 mkcs->client.dev->channel);
+	mkcs->data_in_idx = 0;
+	mkcs->data_out_idx = 0;
+	mkcs->data_out_len = 0;
+	mkcs->phase = KCS_PHASE_IDLE;
+	set_state(mkcs, IDLE_STATE);
+	kcs_bmc_disable_device(mkcs->client.dev, &mkcs->client);
+	return 0;
+}
+
+static const struct net_device_ops mctp_kcs_netdev_ops = {
+	.ndo_start_xmit = mctp_kcs_start_xmit,
+	.ndo_open = mctp_kcs_ndo_open,
+	.ndo_stop = mctp_kcs_ndo_stop,
+};
+
+static void mctp_kcs_setup(struct net_device *ndev)
+{
+	ndev->type = ARPHRD_MCTP;
+
+	/* we limit at the fixed MTU, which is also the MCTP-standard
+	 * baseline MTU, so is also our minimum
+	 */
+	ndev->mtu = MCTP_KCS_MTU;
+	ndev->max_mtu = MCTP_KCS_MTU;
+	ndev->min_mtu = MCTP_KCS_MTU;
+
+	ndev->hard_header_len = 0;
+	ndev->addr_len = 0;
+	ndev->tx_queue_len = DEFAULT_TX_QUEUE_LEN;
+	ndev->flags = IFF_NOARP;
+	ndev->netdev_ops = &mctp_kcs_netdev_ops;
+	ndev->needs_free_netdev = true;
+}
+
+static void kcs_bmc_ipmi_force_abort(struct mctp_kcs *mkcs)
+{
+	dev_err(mkcs->client.dev->dev,
+		"Error! Force abort on KCS communication");
+	set_state(mkcs, ERROR_STATE);
+	kcs_bmc_read_data(mkcs->client.dev);
+	kcs_bmc_write_data(mkcs->client.dev, KCS_ZERO_DATA);
+	mkcs->phase = KCS_PHASE_ERROR;
+	mkcs->data_in_idx = 0;
+}
+
+static void kcs_bmc_ipmi_handle_data(struct mctp_kcs *mkcs)
+{
+	struct kcs_bmc_device *kcs_bmc = mkcs->client.dev;
+	u8 data;
+
+	switch (mkcs->phase) {
+	case KCS_PHASE_WRITE_START:
+		dev_dbg(kcs_bmc->dev, "%s: KCS_PHASE_WRITE_START", __func__);
+		mkcs->phase = KCS_PHASE_WRITE_DATA;
+		fallthrough;
+
+	case KCS_PHASE_WRITE_DATA:
+		dev_dbg(kcs_bmc->dev, "%s: KCS_PHASE_WRITE_DATA", __func__);
+		if (mkcs->data_in_idx < KCS_MSG_BUFSIZ) {
+			set_state(mkcs, WRITE_STATE);
+			kcs_bmc_write_data(kcs_bmc, KCS_ZERO_DATA);
+			mkcs->data_in[mkcs->data_in_idx++] =
+				kcs_bmc_read_data(kcs_bmc);
+			dev_dbg(kcs_bmc->dev,
+				"%s: KCS_PHASE_WRITE_DATA: data_in[%d]=0x%02x",
+				__func__, mkcs->data_in_idx - 1,
+				mkcs->data_in[mkcs->data_in_idx - 1]);
+		} else {
+			kcs_bmc_ipmi_force_abort(mkcs);
+			mkcs->error = KCS_LENGTH_ERROR;
+		}
+		break;
+
+	case KCS_PHASE_WRITE_END_CMD:
+		dev_dbg(kcs_bmc->dev, "%s: KCS_PHASE_WRITE_END_CMD", __func__);
+		if (mkcs->data_in_idx < KCS_MSG_BUFSIZ) {
+			set_state(mkcs, READ_STATE);
+			mkcs->data_in[mkcs->data_in_idx++] =
+				kcs_bmc_read_data(kcs_bmc);
+			dev_dbg(kcs_bmc->dev,
+				"%s: KCS_PHASE_WRITE_END_CMD: data_in[%d]=0x%02x",
+				__func__, mkcs->data_in_idx - 1,
+				mkcs->data_in[mkcs->data_in_idx - 1]);
+			mkcs->phase = KCS_PHASE_WRITE_DONE;
+			schedule_work(&mkcs->rx_work);
+		} else {
+			kcs_bmc_ipmi_force_abort(mkcs);
+			mkcs->error = KCS_LENGTH_ERROR;
+		}
+		break;
+
+	case KCS_PHASE_READ:
+		dev_dbg(kcs_bmc->dev,
+			"%s: KCS_PHASE_READ, data_out_idx=%d, data_out_len=%d",
+			__func__, mkcs->data_out_idx, mkcs->data_out_len);
+		if (mkcs->data_out_idx == mkcs->data_out_len)
+			set_state(mkcs, IDLE_STATE);
+
+		data = kcs_bmc_read_data(kcs_bmc);
+		if (data != KCS_CMD_READ_BYTE) {
+			dev_dbg(kcs_bmc->dev,
+				"%s: error! data is not equal to KCS_CMD_READ_BYTE",
+				__func__);
+			set_state(mkcs, ERROR_STATE);
+			kcs_bmc_write_data(kcs_bmc, KCS_ZERO_DATA);
+			break;
+		}
+
+		if (mkcs->data_out_idx == mkcs->data_out_len) {
+			kcs_bmc_write_data(kcs_bmc, KCS_ZERO_DATA);
+			mkcs->netdev->stats.tx_bytes += mkcs->data_out_len;
+			mkcs->netdev->stats.tx_packets++;
+			mkcs->phase = KCS_PHASE_IDLE;
+			if (netif_queue_stopped(mkcs->netdev))
+				netif_start_queue(mkcs->netdev);
+			break;
+		}
+
+		dev_dbg(kcs_bmc->dev, "%s: KCS_PHASE_READ: data_out[%d]=0x%02x",
+			__func__, mkcs->data_out_idx,
+			mkcs->data_out[mkcs->data_out_idx]);
+		kcs_bmc_write_data(kcs_bmc,
+				   mkcs->data_out[mkcs->data_out_idx++]);
+		break;
+
+	case KCS_PHASE_ABORT_ERROR1:
+		dev_dbg(kcs_bmc->dev, "%s: KCS_PHASE_ABORT_ERROR1", __func__);
+		set_state(mkcs, READ_STATE);
+		kcs_bmc_read_data(kcs_bmc);
+		kcs_bmc_write_data(kcs_bmc, mkcs->error);
+		mkcs->phase = KCS_PHASE_ABORT_ERROR2;
+		break;
+
+	case KCS_PHASE_ABORT_ERROR2:
+		dev_dbg(kcs_bmc->dev, "%s: KCS_PHASE_ABORT_ERROR2", __func__);
+		set_state(mkcs, IDLE_STATE);
+		kcs_bmc_read_data(kcs_bmc);
+		kcs_bmc_write_data(kcs_bmc, KCS_ZERO_DATA);
+		mkcs->phase = KCS_PHASE_IDLE;
+		break;
+
+	default:
+		dev_dbg(kcs_bmc->dev, "%s: unknown KCS phase", __func__);
+		kcs_bmc_ipmi_force_abort(mkcs);
+		break;
+	}
+}
+
+static void kcs_bmc_ipmi_handle_cmd(struct mctp_kcs *mkcs)
+{
+	struct kcs_bmc_device *kcs_bmc = mkcs->client.dev;
+
+	set_state(mkcs, WRITE_STATE);
+	kcs_bmc_write_data(kcs_bmc, KCS_ZERO_DATA);
+
+	switch (kcs_bmc_read_data(kcs_bmc)) {
+	case KCS_CMD_WRITE_START:
+		dev_dbg(kcs_bmc->dev, "%s: KCS_CMD_WRITE_START", __func__);
+		mkcs->phase = KCS_PHASE_WRITE_START;
+		mkcs->error = KCS_NO_ERROR;
+		mkcs->data_in_idx = 0;
+		break;
+
+	case KCS_CMD_WRITE_END:
+		dev_dbg(kcs_bmc->dev, "%s: KCS_CMD_WRITE_END", __func__);
+		if (mkcs->phase != KCS_PHASE_WRITE_DATA) {
+			kcs_bmc_ipmi_force_abort(mkcs);
+			break;
+		}
+		mkcs->phase = KCS_PHASE_WRITE_END_CMD;
+		break;
+
+	case KCS_CMD_GET_STATUS_ABORT:
+		dev_dbg(kcs_bmc->dev, "%s: KCS_CMD_GET_STATUS_ABORT", __func__);
+		if (mkcs->error == KCS_NO_ERROR)
+			mkcs->error = KCS_ABORTED_BY_COMMAND;
+
+		mkcs->phase = KCS_PHASE_ABORT_ERROR1;
+		mkcs->data_in_idx = 0;
+		break;
+
+	default:
+		dev_dbg(kcs_bmc->dev, "%s: unknown KCS command", __func__);
+		kcs_bmc_ipmi_force_abort(mkcs);
+		mkcs->error = KCS_ILLEGAL_CONTROL_CODE;
+		break;
+	}
+}
+
+static struct mctp_kcs *client_to_mctp_kcs(struct kcs_bmc_client *client)
+{
+	return container_of(client, struct mctp_kcs, client);
+}
+
+static irqreturn_t kcs_bmc_mctp_event(struct kcs_bmc_client *client)
+{
+	struct mctp_kcs *mkcs;
+	u8 status;
+	int ret;
+
+	mkcs = client_to_mctp_kcs(client);
+	if (!mkcs) {
+		dev_err(client->dev->dev,
+			"%s: error! can't find mctp_kcs from KCS client",
+			__func__);
+		return IRQ_NONE;
+	}
+
+	spin_lock(&mkcs->lock);
+
+	status = kcs_bmc_read_status(client->dev);
+	if (status & KCS_STATUS_IBF) {
+		if (status & KCS_STATUS_CMD_DAT)
+			kcs_bmc_ipmi_handle_cmd(mkcs);
+		else
+			kcs_bmc_ipmi_handle_data(mkcs);
+
+		ret = IRQ_HANDLED;
+	} else {
+		ret = IRQ_NONE;
+	}
+
+	spin_unlock(&mkcs->lock);
+
+	return ret;
+}
+
+static const struct kcs_bmc_client_ops kcs_bmc_mctp_client_ops = {
+	.event = kcs_bmc_mctp_event,
+};
+
+static DEFINE_SPINLOCK(kcs_bmc_mctp_instances_lock);
+static LIST_HEAD(kcs_bmc_mctp_instances);
+
+static int kcs_bmc_mctp_add_device(struct kcs_bmc_device *kcs_bmc)
+{
+	struct net_device *ndev;
+	struct mctp_kcs *mkcs;
+	char name[32];
+	int rc;
+
+	snprintf(name, sizeof(name), "mctpkcs%d", kcs_bmc->channel);
+
+	ndev = alloc_netdev(sizeof(*mkcs), name, NET_NAME_ENUM, mctp_kcs_setup);
+	if (!ndev) {
+		dev_err_probe(kcs_bmc->dev, -ENOMEM,
+			      "alloc_netdev failed for KCS channel %d\n",
+			      kcs_bmc->channel);
+		return -ENOMEM;
+	}
+
+	mkcs = netdev_priv(ndev);
+	mkcs->netdev = ndev;
+	mkcs->client.dev = kcs_bmc;
+	mkcs->client.ops = &kcs_bmc_mctp_client_ops;
+	mkcs->data_in = devm_kmalloc(kcs_bmc->dev, KCS_MSG_BUFSIZ, GFP_KERNEL);
+	if (!mkcs->data_in) {
+		dev_err_probe(
+			kcs_bmc->dev, -ENOMEM,
+			"failed to allocate data_in buffer for KCS channel %d\n",
+			kcs_bmc->channel);
+		rc = -ENOMEM;
+		goto free_netdev;
+	}
+	mkcs->data_out = devm_kmalloc(kcs_bmc->dev, KCS_MSG_BUFSIZ, GFP_KERNEL);
+	if (!mkcs->data_out) {
+		dev_err_probe(
+			kcs_bmc->dev, -ENOMEM,
+			"failed to allocate data_out buffer for KCS channel %d\n",
+			kcs_bmc->channel);
+		rc = -ENOMEM;
+		goto free_netdev;
+	}
+
+	INIT_WORK(&mkcs->rx_work, mctp_kcs_rx_work);
+
+	rc = register_netdev(ndev);
+	if (rc)
+		goto free_netdev;
+
+	spin_lock_irq(&kcs_bmc_mctp_instances_lock);
+	list_add(&mkcs->entry, &kcs_bmc_mctp_instances);
+	spin_unlock_irq(&kcs_bmc_mctp_instances_lock);
+
+	dev_info(kcs_bmc->dev, "Add MCTP client for the KCS channel %d",
+		 kcs_bmc->channel);
+	return 0;
+
+free_netdev:
+	free_netdev(ndev);
+
+	return rc;
+}
+
+static int kcs_bmc_mctp_remove_device(struct kcs_bmc_device *kcs_bmc)
+{
+	struct mctp_kcs *mkcs = NULL, *pos;
+
+	dev_info(kcs_bmc->dev, "Remove MCTP client for the KCS channel %d",
+		 kcs_bmc->channel);
+	spin_lock_irq(&kcs_bmc_mctp_instances_lock);
+	list_for_each_entry(pos, &kcs_bmc_mctp_instances, entry) {
+		if (pos->client.dev == kcs_bmc) {
+			mkcs = pos;
+			list_del(&pos->entry);
+			break;
+		}
+	}
+	spin_unlock_irq(&kcs_bmc_mctp_instances_lock);
+
+	if (!mkcs)
+		return -ENODEV;
+
+	unregister_netdev(mkcs->netdev);
+	free_netdev(mkcs->netdev);
+	kcs_bmc_disable_device(kcs_bmc, &mkcs->client);
+	devm_kfree(kcs_bmc->dev, mkcs->data_out);
+	devm_kfree(kcs_bmc->dev, mkcs->data_in);
+	return 0;
+}
+
+static const struct kcs_bmc_driver_ops kcs_bmc_mctp_driver_ops = {
+	.add_device = kcs_bmc_mctp_add_device,
+	.remove_device = kcs_bmc_mctp_remove_device,
+};
+
+static struct kcs_bmc_driver kcs_bmc_mctp_driver = {
+	.ops = &kcs_bmc_mctp_driver_ops,
+};
+
+static int __init mctp_kcs_init(void)
+{
+	kcs_bmc_register_driver(&kcs_bmc_mctp_driver);
+	return 0;
+}
+
+static void __exit mctp_kcs_exit(void)
+{
+	kcs_bmc_unregister_driver(&kcs_bmc_mctp_driver);
+}
+
+module_init(mctp_kcs_init);
+module_exit(mctp_kcs_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Konstantin Aladyshev <aladyshev22@gmail.com>");
+MODULE_DESCRIPTION("MCTP KCS transport");
-- 
2.25.1

Re: [PATCH v5 3/3] mctp: Add MCTP-over-KCS transport binding

[Jonathan Cameron]

On Tue, 10 Oct 2023 15:23:21 +0300
Konstantin Aladyshev <aladyshev22@gmail.com> wrote:

> This change adds a MCTP KCS transport binding, as defined by the DMTF
> specification DSP0254 - "MCTP KCS Transport Binding".
> A MCTP protocol network device is created for each KCS channel found in
> the system.
> The interrupt code for the KCS state machine is based on the current
> IPMI KCS driver.
> 
> Signed-off-by: Konstantin Aladyshev <aladyshev22@gmail.com>

Hi Konstantin.

Many of the comments I have inline will be more about general KCS issues
that need sorting out.  Whether this can move forwards before that
(or whether to take any noticed of this) is a question for relevant
maintainers.

BTW it's fine to propose fixes /cleanup to a subsystem alongside a new driver
if you do fancy taking on some of the issues with managed allocations etc called out.

Jonathan


> diff --git a/drivers/net/mctp/mctp-kcs.c b/drivers/net/mctp/mctp-kcs.c
> new file mode 100644
> index 000000000000..b0d903609c64
> --- /dev/null
> +++ b/drivers/net/mctp/mctp-kcs.c
> @@ -0,0 +1,600 @@


...

> +
> +static DEFINE_SPINLOCK(kcs_bmc_mctp_instances_lock);
> +static LIST_HEAD(kcs_bmc_mctp_instances);
> +
> +static int kcs_bmc_mctp_add_device(struct kcs_bmc_device *kcs_bmc)
> +{
> +	struct net_device *ndev;
> +	struct mctp_kcs *mkcs;
> +	char name[32];
> +	int rc;
> +
> +	snprintf(name, sizeof(name), "mctpkcs%d", kcs_bmc->channel);
> +
> +	ndev = alloc_netdev(sizeof(*mkcs), name, NET_NAME_ENUM, mctp_kcs_setup);
> +	if (!ndev) {
> +		dev_err_probe(kcs_bmc->dev, -ENOMEM,
> +			      "alloc_netdev failed for KCS channel %d\n",
> +			      kcs_bmc->channel);
> +		return -ENOMEM;
> +	}
> +
> +	mkcs = netdev_priv(ndev);
> +	mkcs->netdev = ndev;
> +	mkcs->client.dev = kcs_bmc;
> +	mkcs->client.ops = &kcs_bmc_mctp_client_ops;
> +	mkcs->data_in = devm_kmalloc(kcs_bmc->dev, KCS_MSG_BUFSIZ, GFP_KERNEL);
> +	if (!mkcs->data_in) {
> +		dev_err_probe(
> +			kcs_bmc->dev, -ENOMEM,
> +			"failed to allocate data_in buffer for KCS channel %d\n",
> +			kcs_bmc->channel);
> +		rc = -ENOMEM;
> +		goto free_netdev;
> +	}
> +	mkcs->data_out = devm_kmalloc(kcs_bmc->dev, KCS_MSG_BUFSIZ, GFP_KERNEL);
> +	if (!mkcs->data_out) {
> +		dev_err_probe(
> +			kcs_bmc->dev, -ENOMEM,
> +			"failed to allocate data_out buffer for KCS channel %d\n",
> +			kcs_bmc->channel);
> +		rc = -ENOMEM;
> +		goto free_netdev;
> +	}
> +
> +	INIT_WORK(&mkcs->rx_work, mctp_kcs_rx_work);
> +
> +	rc = register_netdev(ndev);
> +	if (rc)
> +		goto free_netdev;
> +
> +	spin_lock_irq(&kcs_bmc_mctp_instances_lock);
> +	list_add(&mkcs->entry, &kcs_bmc_mctp_instances);
> +	spin_unlock_irq(&kcs_bmc_mctp_instances_lock);
> +
> +	dev_info(kcs_bmc->dev, "Add MCTP client for the KCS channel %d",
> +		 kcs_bmc->channel);
> +	return 0;
> +
> +free_netdev:
> +	free_netdev(ndev);

Mixing devm and non devm is something you should not do. 
Very simple rule that must be kept to is that you stop using devm for
any calls in an add_device / probe() function at the first line that needs
manual cleanup.

Use devm_add_action_or_reset() for this case as you can add a custom
callback to the devm managed queue.

The reason this all matters is that devm cleanup happens after error paths
/ remove_device() callbacks and as such it makes a reviewer have to reason
about whether there are any dependencies that are a result of the reordering.
Tearing down in exact reverse order of setup is a lot easier to do!


> +
> +	return rc;
> +}
> +
> +static int kcs_bmc_mctp_remove_device(struct kcs_bmc_device *kcs_bmc)
> +{
> +	struct mctp_kcs *mkcs = NULL, *pos;
> +
> +	dev_info(kcs_bmc->dev, "Remove MCTP client for the KCS channel %d",
> +		 kcs_bmc->channel);
> +	spin_lock_irq(&kcs_bmc_mctp_instances_lock);
> +	list_for_each_entry(pos, &kcs_bmc_mctp_instances, entry) {

I've commented on this before, but this lookup should not be necessary.
It should be possible to go directly from kcs_bmc entry as registered
to the mctp_kcs structure.  Typical approach being to embed the structure
or using some drvdata type field that add has filled in with appropriate
pointer.

There is a need for the kcs subsystem to manage which devices it
calls this on.  Currently this also serves the purpose of filtering
for that.  If not going to do management at subsystem layer (some smaller
subsystems don't) then use an enum to add a type to kcs_bmc
and have each driver add a new one.  You can check that in driver
or in core code. Doesn't matter which as check will be trivial.


> +		if (pos->client.dev == kcs_bmc) {
> +			mkcs = pos;
> +			list_del(&pos->entry);
> +			break;
> +		}
> +	}
> +	spin_unlock_irq(&kcs_bmc_mctp_instances_lock);
> +
> +	if (!mkcs)
> +		return -ENODEV;
> +
> +	unregister_netdev(mkcs->netdev);
> +	free_netdev(mkcs->netdev);
> +	kcs_bmc_disable_device(kcs_bmc, &mkcs->client);
> +	devm_kfree(kcs_bmc->dev, mkcs->data_out);
> +	devm_kfree(kcs_bmc->dev, mkcs->data_in);

I don't like mixture of letting devm delete these on remove and
it being done manually here.

Note that if you just didn't have these two calls, they'd be deleted soon
after this exit anyway.

If devm is any use when combined with kcs, these will be freed shortly after
this anyway. If it isn't of use with this subsystem then then they won't
do the right thing in the add_device callback error cases.

I'd test if it does anything at all via each path where we'd expect it to
(driver unbind, device removal, error in add_device callback)

In all those cases the devm unwinding callbacks should be called. 
(add a bonus one for testing with devm_add_action_or_reset() and
see if that one is called in each path).

I'm very suspicious of this working as not setting the normal calls
to make it happen.
e.g. for I2c, it happens here:
https://elixir.bootlin.com/linux/latest/source/drivers/i2c/i2c-core-base.c#L597
for the error path with a call to devres_release_group()
in other subsystems it's handled by the bus_type logic which ultimately
calls device_unbind_cleanup() in probe() failure.  That calls
devres_release_all() triggering the tear down paths.

However I might be missing a route by which the cleanup happens.

Anyhow, if that is fixed, these devm cleanup calls in remove_device()
should not be here.  The whole point of devm is to simplify this - if
you manually have to unwind it the advantages go away and you should
manage things explicitly.



> +	return 0;
> +}
> +
> +static const struct kcs_bmc_driver_ops kcs_bmc_mctp_driver_ops = {
> +	.add_device = kcs_bmc_mctp_add_device,
> +	.remove_device = kcs_bmc_mctp_remove_device,
> +};
> +
> +static struct kcs_bmc_driver kcs_bmc_mctp_driver = {
> +	.ops = &kcs_bmc_mctp_driver_ops,
> +};
> +
> +static int __init mctp_kcs_init(void)
> +{
> +	kcs_bmc_register_driver(&kcs_bmc_mctp_driver);
> +	return 0;
> +}
> +
> +static void __exit mctp_kcs_exit(void)
> +{
> +	kcs_bmc_unregister_driver(&kcs_bmc_mctp_driver);
> +}
> +
> +module_init(mctp_kcs_init);
> +module_exit(mctp_kcs_exit);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Konstantin Aladyshev <aladyshev22@gmail.com>");
> +MODULE_DESCRIPTION("MCTP KCS transport");