[PATCH v4 0/2] i2c-designware: Add support for AMD PSP semaphore

[PATCH v4 0/2] i2c-designware: Add support for AMD PSP semaphore

[Jan Dabros]

This patchset comprises support for new i2c-designware controller setup on some
AMD Cezanne SoCs, where x86 is sharing i2c bus with PSP. PSP uses the same
controller and acts as an i2c arbitrator there (x86 is leasing bus from it).

First commit aims to improve generic i2c-designware code by adding extra locking
on probe() and disable() paths. I would like to ask someone with access to
boards which use Intel BayTrail(CONFIG_I2C_DESIGNWARE_BAYTRAIL) to verify
behavior of my changes on such setup.

Second commit adds support for new PSP semaphore arbitration mechanism.
Implementation is similar to the one from i2c-designware-baytrail.c however
there are two main differences:
1) Add new ACPI ID in order to protect against silent binding of the old driver
to the setup with PSP semaphore. Extra flag ARBITRATION_SEMAPHORE added to this
new _HID allows to recognize setup with PSP.
2) Beside acquire_lock() and release_lock() methods we are also applying quirks
to the lock_bus() and unlock_bus() global adapter methods. With this in place
all i2c clients drivers may lock i2c bus for a desired number of i2c
transactions (e.g. write-wait-read) without being aware of that such bus is
shared with another entity.

This patchset is a follow-up to the RFC sent earlier on LKML [1], with review
comments applied.

Looking forward to some feedback.

[1] https://lkml.org/lkml/2021/12/22/219

v3->v4:
* Remove unnecessary alignment of psp_i2c_req
* Add missing bits.h header
* Make use of USEC_PER_MSEC
* Simplify `if` conditions with unsigned variables
* Add additional comments

v2 -> v3:
* Change X86_64 Kconfig dependency to X86_MSR
* Switch from phys_addr_t to u64 in mailbox struct definition
* Remove redundant guard in semaphores' probes
* Add comments about error propagation
* Move credits for kernel test robot into changelog

v1 -> v2:
* Remove usage of unions
* Get rid of unnecessary __packed attributes
* Switch to use iopoll.h and bitfields.h APIs were applicable
* Follow the convention to check for the error first
* Reorder entries (includes, table entries) alphabetically
* Add necessary includes
* Add Kconfig dependency on X86_64
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: kernel test robot <lkp@intel.com>
* Modify probe() to use terminating entry for traversing through table
  instead of ARRAY_SIZE
* Fix typos in comments
* Rebase patchset

Jan Dabros (2):
  i2c: designware: Add missing locks
  i2c: designware: Add AMD PSP I2C bus support

 MAINTAINERS                                  |   1 +
 drivers/acpi/acpi_apd.c                      |   7 +-
 drivers/i2c/busses/Kconfig                   |  11 +
 drivers/i2c/busses/Makefile                  |   1 +
 drivers/i2c/busses/i2c-designware-amdpsp.c   | 394 +++++++++++++++++++
 drivers/i2c/busses/i2c-designware-baytrail.c |  12 +-
 drivers/i2c/busses/i2c-designware-common.c   |  12 +
 drivers/i2c/busses/i2c-designware-core.h     |  18 +-
 drivers/i2c/busses/i2c-designware-master.c   |   6 +
 drivers/i2c/busses/i2c-designware-platdrv.c  |  60 +++
 10 files changed, 510 insertions(+), 12 deletions(-)
 create mode 100644 drivers/i2c/busses/i2c-designware-amdpsp.c

-- 
2.35.0.263.gb82422642f-goog

[PATCH v4 1/2] i2c: designware: Add missing locks

[Jan Dabros]

All accesses to controller's registers should be protected on
probe, disable and xfer paths. This is needed for i2c bus controllers
that are shared with but not controller by kernel.

Signed-off-by: Jan Dabros <jsd@semihalf.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/i2c/busses/i2c-designware-common.c | 12 ++++++++++++
 drivers/i2c/busses/i2c-designware-master.c |  6 ++++++
 2 files changed, 18 insertions(+)

diff --git a/drivers/i2c/busses/i2c-designware-common.c b/drivers/i2c/busses/i2c-designware-common.c
index bf2a4920638a..9f8574320eb2 100644
--- a/drivers/i2c/busses/i2c-designware-common.c
+++ b/drivers/i2c/busses/i2c-designware-common.c
@@ -578,7 +578,12 @@ int i2c_dw_set_fifo_size(struct dw_i2c_dev *dev)
 	 * Try to detect the FIFO depth if not set by interface driver,
 	 * the depth could be from 2 to 256 from HW spec.
 	 */
+	ret = i2c_dw_acquire_lock(dev);
+	if (ret)
+		return ret;
+
 	ret = regmap_read(dev->map, DW_IC_COMP_PARAM_1, &param);
+	i2c_dw_release_lock(dev);
 	if (ret)
 		return ret;
 
@@ -607,6 +612,11 @@ u32 i2c_dw_func(struct i2c_adapter *adap)
 void i2c_dw_disable(struct dw_i2c_dev *dev)
 {
 	u32 dummy;
+	int ret;
+
+	ret = i2c_dw_acquire_lock(dev);
+	if (ret)
+		return;
 
 	/* Disable controller */
 	__i2c_dw_disable(dev);
@@ -614,6 +624,8 @@ void i2c_dw_disable(struct dw_i2c_dev *dev)
 	/* Disable all interrupts */
 	regmap_write(dev->map, DW_IC_INTR_MASK, 0);
 	regmap_read(dev->map, DW_IC_CLR_INTR, &dummy);
+
+	i2c_dw_release_lock(dev);
 }
 
 void i2c_dw_disable_int(struct dw_i2c_dev *dev)
diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
index 9177463c2cbb..1a4b23556db3 100644
--- a/drivers/i2c/busses/i2c-designware-master.c
+++ b/drivers/i2c/busses/i2c-designware-master.c
@@ -905,7 +905,13 @@ int i2c_dw_probe_master(struct dw_i2c_dev *dev)
 		irq_flags = IRQF_SHARED | IRQF_COND_SUSPEND;
 	}
 
+	ret = i2c_dw_acquire_lock(dev);
+	if (ret)
+		return ret;
+
 	i2c_dw_disable_int(dev);
+	i2c_dw_release_lock(dev);
+
 	ret = devm_request_irq(dev->dev, dev->irq, i2c_dw_isr, irq_flags,
 			       dev_name(dev->dev), dev);
 	if (ret) {
-- 
2.35.0.263.gb82422642f-goog

Re: [PATCH v4 1/2] i2c: designware: Add missing locks

[Jarkko Nikula]

On 2/8/22 16:12, Jan Dabros wrote:
> All accesses to controller's registers should be protected on
> probe, disable and xfer paths. This is needed for i2c bus controllers
> that are shared with but not controller by kernel.
> 
> Signed-off-by: Jan Dabros <jsd@semihalf.com>
> Reviewed-by: Hans de Goede <hdegoede@redhat.com>
> ---
>   drivers/i2c/busses/i2c-designware-common.c | 12 ++++++++++++
>   drivers/i2c/busses/i2c-designware-master.c |  6 ++++++
>   2 files changed, 18 insertions(+)
> 
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>

Shortly tested by rmmod & modprobe loop.

Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>

Re: [PATCH v4 1/2] i2c: designware: Add missing locks

[Andy Shevchenko]

On Tue, Feb 08, 2022 at 03:12:17PM +0100, Jan Dabros wrote:
> All accesses to controller's registers should be protected on
> probe, disable and xfer paths. This is needed for i2c bus controllers
> that are shared with but not controller by kernel.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

> Signed-off-by: Jan Dabros <jsd@semihalf.com>
> Reviewed-by: Hans de Goede <hdegoede@redhat.com>
> ---
>  drivers/i2c/busses/i2c-designware-common.c | 12 ++++++++++++
>  drivers/i2c/busses/i2c-designware-master.c |  6 ++++++
>  2 files changed, 18 insertions(+)
> 
> diff --git a/drivers/i2c/busses/i2c-designware-common.c b/drivers/i2c/busses/i2c-designware-common.c
> index bf2a4920638a..9f8574320eb2 100644
> --- a/drivers/i2c/busses/i2c-designware-common.c
> +++ b/drivers/i2c/busses/i2c-designware-common.c
> @@ -578,7 +578,12 @@ int i2c_dw_set_fifo_size(struct dw_i2c_dev *dev)
>  	 * Try to detect the FIFO depth if not set by interface driver,
>  	 * the depth could be from 2 to 256 from HW spec.
>  	 */
> +	ret = i2c_dw_acquire_lock(dev);
> +	if (ret)
> +		return ret;
> +
>  	ret = regmap_read(dev->map, DW_IC_COMP_PARAM_1, &param);
> +	i2c_dw_release_lock(dev);
>  	if (ret)
>  		return ret;
>  
> @@ -607,6 +612,11 @@ u32 i2c_dw_func(struct i2c_adapter *adap)
>  void i2c_dw_disable(struct dw_i2c_dev *dev)
>  {
>  	u32 dummy;
> +	int ret;
> +
> +	ret = i2c_dw_acquire_lock(dev);
> +	if (ret)
> +		return;
>  
>  	/* Disable controller */
>  	__i2c_dw_disable(dev);
> @@ -614,6 +624,8 @@ void i2c_dw_disable(struct dw_i2c_dev *dev)
>  	/* Disable all interrupts */
>  	regmap_write(dev->map, DW_IC_INTR_MASK, 0);
>  	regmap_read(dev->map, DW_IC_CLR_INTR, &dummy);
> +
> +	i2c_dw_release_lock(dev);
>  }
>  
>  void i2c_dw_disable_int(struct dw_i2c_dev *dev)
> diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
> index 9177463c2cbb..1a4b23556db3 100644
> --- a/drivers/i2c/busses/i2c-designware-master.c
> +++ b/drivers/i2c/busses/i2c-designware-master.c
> @@ -905,7 +905,13 @@ int i2c_dw_probe_master(struct dw_i2c_dev *dev)
>  		irq_flags = IRQF_SHARED | IRQF_COND_SUSPEND;
>  	}
>  
> +	ret = i2c_dw_acquire_lock(dev);
> +	if (ret)
> +		return ret;
> +
>  	i2c_dw_disable_int(dev);
> +	i2c_dw_release_lock(dev);
> +
>  	ret = devm_request_irq(dev->dev, dev->irq, i2c_dw_isr, irq_flags,
>  			       dev_name(dev->dev), dev);
>  	if (ret) {
> -- 
> 2.35.0.263.gb82422642f-goog
> 

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v4 1/2] i2c: designware: Add missing locks

[Wolfram Sang]

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On Tue, Feb 08, 2022 at 03:12:17PM +0100, Jan Dabros wrote:
> All accesses to controller's registers should be protected on
> probe, disable and xfer paths. This is needed for i2c bus controllers
> that are shared with but not controller by kernel.
> 
> Signed-off-by: Jan Dabros <jsd@semihalf.com>
> Reviewed-by: Hans de Goede <hdegoede@redhat.com>

Applied to for-next, thanks!


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Re: [PATCH v4 1/2] i2c: designware: Add missing locks

[Jan Dąbroś]

czw., 10 lut 2022 o 23:08 Wolfram Sang <wsa@kernel.org> napisał(a):
>
> On Tue, Feb 08, 2022 at 03:12:17PM +0100, Jan Dabros wrote:
> > All accesses to controller's registers should be protected on
> > probe, disable and xfer paths. This is needed for i2c bus controllers
> > that are shared with but not controller by kernel.
> >
> > Signed-off-by: Jan Dabros <jsd@semihalf.com>
> > Reviewed-by: Hans de Goede <hdegoede@redhat.com>
>
> Applied to for-next, thanks!

Thanks!

Best Regards,
Jan

[PATCH v4 2/2] i2c: designware: Add AMD PSP I2C bus support

[Jan Dabros]

Implement an I2C controller sharing mechanism between the host (kernel)
and PSP co-processor on some platforms equipped with AMD Cezanne SoC.

On these platforms we need to implement "software" i2c arbitration.
Default arbitration owner is PSP and kernel asks for acquire as well
as inform about release of the i2c bus via mailbox mechanism.

            +---------+
 <- ACQUIRE |         |
  +---------|   CPU   |\
  |         |         | \      +----------+  SDA
  |         +---------+  \     |          |-------
MAILBOX                   +--> |  I2C-DW  |  SCL
  |         +---------+        |          |-------
  |         |         |        +----------+
  +---------|   PSP   |
   <- ACK   |         |
            +---------+

            +---------+
 <- RELEASE |         |
  +---------|   CPU   |
  |         |         |        +----------+  SDA
  |         +---------+        |          |-------
MAILBOX                   +--> |  I2C-DW  |  SCL
  |         +---------+  /     |          |-------
  |         |         | /      +----------+
  +---------|   PSP   |/
   <- ACK   |         |
            +---------+

The solution is similar to i2c-designware-baytrail.c implementation, where
we are using a generic i2c-designware-* driver with a small "wrapper".

In contrary to baytrail semaphore implementation, beside internal
acquire_lock() and release_lock() methods we are also applying quirks to
lock_bus() and unlock_bus() global adapter methods. With this in place
all i2c clients drivers may lock i2c bus for a desired number of i2c
transactions (e.g. write-wait-read) without being aware of that such bus
is shared with another entity.

Modify i2c_dw_probe_lock_support() to select correct semaphore
implementation at runtime, since now we have more than one available.

Configure new matching ACPI ID "AMDI0019" and register
ARBITRATION_SEMAPHORE flag in order to distinguish setup with PSP
arbitration.

Add myself as a reviewer for I2C DesignWare in order to help with reviewing
and testing possible changes touching new i2c-designware-amdpsp.c module.

Signed-off-by: Jan Dabros <jsd@semihalf.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 MAINTAINERS                                  |   1 +
 drivers/acpi/acpi_apd.c                      |   7 +-
 drivers/i2c/busses/Kconfig                   |  11 +
 drivers/i2c/busses/Makefile                  |   1 +
 drivers/i2c/busses/i2c-designware-amdpsp.c   | 394 +++++++++++++++++++
 drivers/i2c/busses/i2c-designware-baytrail.c |  12 +-
 drivers/i2c/busses/i2c-designware-core.h     |  18 +-
 drivers/i2c/busses/i2c-designware-platdrv.c  |  60 +++
 8 files changed, 492 insertions(+), 12 deletions(-)
 create mode 100644 drivers/i2c/busses/i2c-designware-amdpsp.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 69a2935daf6c..fd4888487c45 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -18679,6 +18679,7 @@ SYNOPSYS DESIGNWARE I2C DRIVER
 M:	Jarkko Nikula <jarkko.nikula@linux.intel.com>
 R:	Andy Shevchenko <andriy.shevchenko@linux.intel.com>
 R:	Mika Westerberg <mika.westerberg@linux.intel.com>
+R:	Jan Dabros <jsd@semihalf.com>
 L:	linux-i2c@vger.kernel.org
 S:	Maintained
 F:	drivers/i2c/busses/i2c-designware-*
diff --git a/drivers/acpi/acpi_apd.c b/drivers/acpi/acpi_apd.c
index e7934ba79b02..ad245bbd965e 100644
--- a/drivers/acpi/acpi_apd.c
+++ b/drivers/acpi/acpi_apd.c
@@ -232,12 +232,13 @@ static const struct acpi_device_id acpi_apd_device_ids[] = {
 	/* Generic apd devices */
 #ifdef CONFIG_X86_AMD_PLATFORM_DEVICE
 	{ "AMD0010", APD_ADDR(cz_i2c_desc) },
-	{ "AMDI0010", APD_ADDR(wt_i2c_desc) },
 	{ "AMD0020", APD_ADDR(cz_uart_desc) },
-	{ "AMDI0020", APD_ADDR(cz_uart_desc) },
-	{ "AMDI0022", APD_ADDR(cz_uart_desc) },
 	{ "AMD0030", },
 	{ "AMD0040", APD_ADDR(fch_misc_desc)},
+	{ "AMDI0010", APD_ADDR(wt_i2c_desc) },
+	{ "AMDI0019", APD_ADDR(wt_i2c_desc) },
+	{ "AMDI0020", APD_ADDR(cz_uart_desc) },
+	{ "AMDI0022", APD_ADDR(cz_uart_desc) },
 	{ "HYGO0010", APD_ADDR(wt_i2c_desc) },
 #endif
 #ifdef CONFIG_ARM64
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 42da31c1ab70..5ea26a7aa1d5 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -553,6 +553,17 @@ config I2C_DESIGNWARE_PLATFORM
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-designware-platform.
 
+config I2C_DESIGNWARE_AMDPSP
+	bool "AMD PSP I2C semaphore support"
+	depends on X86_MSR
+	depends on ACPI
+	depends on I2C_DESIGNWARE_PLATFORM
+	help
+	  This driver enables managed host access to the selected I2C bus shared
+	  between AMD CPU and AMD PSP.
+
+	  You should say Y if running on an AMD system equipped with the PSP.
+
 config I2C_DESIGNWARE_BAYTRAIL
 	bool "Intel Baytrail I2C semaphore support"
 	depends on ACPI
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 1d00dce77098..752f47be3fc1 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -54,6 +54,7 @@ i2c-designware-core-y					+= i2c-designware-master.o
 i2c-designware-core-$(CONFIG_I2C_DESIGNWARE_SLAVE) 	+= i2c-designware-slave.o
 obj-$(CONFIG_I2C_DESIGNWARE_PLATFORM)			+= i2c-designware-platform.o
 i2c-designware-platform-y 				:= i2c-designware-platdrv.o
+i2c-designware-platform-$(CONFIG_I2C_DESIGNWARE_AMDPSP)	+= i2c-designware-amdpsp.o
 i2c-designware-platform-$(CONFIG_I2C_DESIGNWARE_BAYTRAIL) += i2c-designware-baytrail.o
 obj-$(CONFIG_I2C_DESIGNWARE_PCI)			+= i2c-designware-pci.o
 i2c-designware-pci-y					:= i2c-designware-pcidrv.o
diff --git a/drivers/i2c/busses/i2c-designware-amdpsp.c b/drivers/i2c/busses/i2c-designware-amdpsp.c
new file mode 100644
index 000000000000..44adb390ecc9
--- /dev/null
+++ b/drivers/i2c/busses/i2c-designware-amdpsp.c
@@ -0,0 +1,394 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/i2c.h>
+#include <linux/io-64-nonatomic-lo-hi.h>
+#include <linux/psp-sev.h>
+#include <linux/types.h>
+
+#include <asm/msr.h>
+
+#include "i2c-designware-core.h"
+
+#define MSR_AMD_PSP_ADDR	0xc00110a2
+#define PSP_MBOX_OFFSET		0x10570
+#define PSP_CMD_TIMEOUT_US	(500 * USEC_PER_MSEC)
+
+#define PSP_I2C_REQ_BUS_CMD		0x64
+#define PSP_I2C_REQ_RETRY_CNT		10
+#define PSP_I2C_REQ_RETRY_DELAY_US	(50 * USEC_PER_MSEC)
+#define PSP_I2C_REQ_STS_OK		0x0
+#define PSP_I2C_REQ_STS_BUS_BUSY	0x1
+#define PSP_I2C_REQ_STS_INV_PARAM	0x3
+
+#define PSP_MBOX_FIELDS_STS		GENMASK(15, 0)
+#define PSP_MBOX_FIELDS_CMD		GENMASK(23, 16)
+#define PSP_MBOX_FIELDS_RESERVED	GENMASK(29, 24)
+#define PSP_MBOX_FIELDS_RECOVERY	BIT(30)
+#define PSP_MBOX_FIELDS_READY		BIT(31)
+
+struct psp_req_buffer_hdr {
+	u32 total_size;
+	u32 status;
+};
+
+enum psp_i2c_req_type {
+	PSP_I2C_REQ_ACQUIRE,
+	PSP_I2C_REQ_RELEASE,
+	PSP_I2C_REQ_MAX
+};
+
+struct psp_i2c_req {
+	struct psp_req_buffer_hdr hdr;
+	enum psp_i2c_req_type type;
+};
+
+struct psp_mbox {
+	u32 cmd_fields;
+	u64 i2c_req_addr;
+} __packed;
+
+static DEFINE_MUTEX(psp_i2c_access_mutex);
+static unsigned long psp_i2c_sem_acquired;
+static void __iomem *mbox_iomem;
+static u32 psp_i2c_access_count;
+static bool psp_i2c_mbox_fail;
+static struct device *psp_i2c_dev;
+
+/*
+ * Implementation of PSP-x86 i2c-arbitration mailbox introduced for AMD Cezanne
+ * family of SoCs.
+ */
+
+static int psp_get_mbox_addr(unsigned long *mbox_addr)
+{
+	unsigned long long psp_mmio;
+
+	if (rdmsrl_safe(MSR_AMD_PSP_ADDR, &psp_mmio))
+		return -EIO;
+
+	*mbox_addr = (unsigned long)(psp_mmio + PSP_MBOX_OFFSET);
+
+	return 0;
+}
+
+static int psp_mbox_probe(void)
+{
+	unsigned long mbox_addr;
+	int ret;
+
+	ret = psp_get_mbox_addr(&mbox_addr);
+	if (ret)
+		return ret;
+
+	mbox_iomem = ioremap(mbox_addr, sizeof(struct psp_mbox));
+	if (!mbox_iomem)
+		return -ENOMEM;
+
+	return 0;
+}
+
+
+/* Recovery field should be equal 0 to start sending commands */
+static int psp_check_mbox_recovery(struct psp_mbox __iomem *mbox)
+{
+	u32 tmp;
+
+	tmp = readl(&mbox->cmd_fields);
+
+	return FIELD_GET(PSP_MBOX_FIELDS_RECOVERY, tmp);
+}
+
+static int psp_wait_cmd(struct psp_mbox __iomem *mbox)
+{
+	u32 tmp, expected;
+
+	/* Expect mbox_cmd to be cleared and ready bit to be set by PSP */
+	expected = FIELD_PREP(PSP_MBOX_FIELDS_READY, 1);
+
+	/*
+	 * Check for readiness of PSP mailbox in a tight loop in order to
+	 * process further as soon as command was consumed.
+	 */
+	return readl_poll_timeout(&mbox->cmd_fields, tmp, (tmp == expected),
+				  0, PSP_CMD_TIMEOUT_US);
+}
+
+/* Status equal to 0 means that PSP succeed processing command */
+static u32 psp_check_mbox_sts(struct psp_mbox __iomem *mbox)
+{
+	u32 cmd_reg;
+
+	cmd_reg = readl(&mbox->cmd_fields);
+
+	return FIELD_GET(PSP_MBOX_FIELDS_STS, cmd_reg);
+}
+
+static int psp_send_cmd(struct psp_i2c_req *req)
+{
+	struct psp_mbox __iomem *mbox = mbox_iomem;
+	phys_addr_t req_addr;
+	u32 cmd_reg;
+
+	if (psp_check_mbox_recovery(mbox))
+		return -EIO;
+
+	if (psp_wait_cmd(mbox))
+		return -EBUSY;
+
+	/*
+	 * Fill mailbox with address of command-response buffer, which will be
+	 * used for sending i2c requests as well as reading status returned by
+	 * PSP. Use physical address of buffer, since PSP will map this region.
+	 */
+	req_addr = __psp_pa((void *)req);
+	writeq(req_addr, &mbox->i2c_req_addr);
+
+	/* Write command register to trigger processing */
+	cmd_reg = FIELD_PREP(PSP_MBOX_FIELDS_CMD, PSP_I2C_REQ_BUS_CMD);
+	writel(cmd_reg, &mbox->cmd_fields);
+
+	if (psp_wait_cmd(mbox))
+		return -ETIMEDOUT;
+
+	if (psp_check_mbox_sts(mbox))
+		return -EIO;
+
+	return 0;
+}
+
+/* Helper to verify status returned by PSP */
+static int check_i2c_req_sts(struct psp_i2c_req *req)
+{
+	int status;
+
+	status = readl(&req->hdr.status);
+
+	switch (status) {
+	case PSP_I2C_REQ_STS_OK:
+		return 0;
+	case PSP_I2C_REQ_STS_BUS_BUSY:
+		return -EBUSY;
+	case PSP_I2C_REQ_STS_INV_PARAM:
+	default:
+		return -EIO;
+	};
+}
+
+static int psp_send_check_i2c_req(struct psp_i2c_req *req)
+{
+	/*
+	 * Errors in x86-PSP i2c-arbitration protocol may occur at two levels:
+	 * 1. mailbox communication - PSP is not operational or some IO errors
+	 * with basic communication had happened;
+	 * 2. i2c-requests - PSP refuses to grant i2c arbitration to x86 for too
+	 * long.
+	 * In order to distinguish between these two in error handling code, all
+	 * errors on the first level (returned by psp_send_cmd) are shadowed by
+	 * -EIO.
+	 */
+	if (psp_send_cmd(req))
+		return -EIO;
+
+	return check_i2c_req_sts(req);
+}
+
+static int psp_send_i2c_req(enum psp_i2c_req_type i2c_req_type)
+{
+	struct psp_i2c_req *req;
+	unsigned long start;
+	int status, ret;
+
+	/* Allocate command-response buffer */
+	req = kzalloc(sizeof(*req), GFP_KERNEL);
+	if (!req)
+		return -ENOMEM;
+
+	req->hdr.total_size = sizeof(*req);
+	req->type = i2c_req_type;
+
+	start = jiffies;
+	ret = read_poll_timeout(psp_send_check_i2c_req, status,
+				(status != -EBUSY),
+				PSP_I2C_REQ_RETRY_DELAY_US,
+				PSP_I2C_REQ_RETRY_CNT * PSP_I2C_REQ_RETRY_DELAY_US,
+				0, req);
+	if (ret)
+		goto cleanup;
+
+	ret = status;
+	if (ret) {
+		goto cleanup;
+	}
+
+	dev_dbg(psp_i2c_dev, "Request accepted by PSP after %ums\n",
+		jiffies_to_msecs(jiffies - start));
+
+cleanup:
+	kfree(req);
+	return ret;
+}
+
+static int psp_acquire_i2c_bus(void)
+{
+	int status;
+
+	mutex_lock(&psp_i2c_access_mutex);
+
+	/* Return early if mailbox malfunctioned */
+	if (psp_i2c_mbox_fail)
+		goto cleanup;
+
+	/*
+	 * Simply increment usage counter and return if PSP semaphore was
+	 * already taken by kernel.
+	 */
+	if (psp_i2c_access_count) {
+		psp_i2c_access_count++;
+		goto cleanup;
+	};
+
+	status = psp_send_i2c_req(PSP_I2C_REQ_ACQUIRE);
+	if (status) {
+		if (status == -ETIMEDOUT)
+			dev_err(psp_i2c_dev, "Timed out waiting for PSP to release I2C bus\n");
+		else
+			dev_err(psp_i2c_dev, "PSP communication error\n");
+
+		dev_err(psp_i2c_dev, "Assume i2c bus is for exclusive host usage\n");
+		psp_i2c_mbox_fail = true;
+		goto cleanup;
+	}
+
+	psp_i2c_sem_acquired = jiffies;
+	psp_i2c_access_count++;
+
+	/*
+	 * In case of errors with PSP arbitrator psp_i2c_mbox_fail variable is
+	 * set above. As a consequence consecutive calls to acquire will bypass
+	 * communication with PSP. At any case i2c bus is granted to the caller,
+	 * thus always return success.
+	 */
+cleanup:
+	mutex_unlock(&psp_i2c_access_mutex);
+	return 0;
+}
+
+static void psp_release_i2c_bus(void)
+{
+	int status;
+
+	mutex_lock(&psp_i2c_access_mutex);
+
+	/* Return early if mailbox was malfunctional */
+	if (psp_i2c_mbox_fail)
+		goto cleanup;
+
+	/*
+	 * If we are last owner of PSP semaphore, need to release aribtration
+	 * via mailbox.
+	 */
+	psp_i2c_access_count--;
+	if (psp_i2c_access_count)
+		goto cleanup;
+
+	/* Send a release command to PSP */
+	status = psp_send_i2c_req(PSP_I2C_REQ_RELEASE);
+	if (status) {
+		if (status == -ETIMEDOUT)
+			dev_err(psp_i2c_dev, "Timed out waiting for PSP to acquire I2C bus\n");
+		else
+			dev_err(psp_i2c_dev, "PSP communication error\n");
+
+		dev_err(psp_i2c_dev, "Assume i2c bus is for exclusive host usage\n");
+		psp_i2c_mbox_fail = true;
+		goto cleanup;
+	}
+
+	dev_dbg(psp_i2c_dev, "PSP semaphore held for %ums\n",
+		jiffies_to_msecs(jiffies - psp_i2c_sem_acquired));
+
+cleanup:
+	mutex_unlock(&psp_i2c_access_mutex);
+}
+
+/*
+ * Locking methods are based on the default implementation from
+ * drivers/i2c/i2c-core-base.c, but with psp acquire and release operations
+ * added. With this in place we can ensure that i2c clients on the bus shared
+ * with psp are able to lock HW access to the bus for arbitrary number of
+ * operations - that is e.g. write-wait-read.
+ */
+static void i2c_adapter_dw_psp_lock_bus(struct i2c_adapter *adapter,
+					unsigned int flags)
+{
+	psp_acquire_i2c_bus();
+	rt_mutex_lock_nested(&adapter->bus_lock, i2c_adapter_depth(adapter));
+}
+
+static int i2c_adapter_dw_psp_trylock_bus(struct i2c_adapter *adapter,
+					  unsigned int flags)
+{
+	int ret;
+
+	ret = rt_mutex_trylock(&adapter->bus_lock);
+	if (ret)
+		return ret;
+
+	psp_acquire_i2c_bus();
+
+	return ret;
+}
+
+static void i2c_adapter_dw_psp_unlock_bus(struct i2c_adapter *adapter,
+					  unsigned int flags)
+{
+	psp_release_i2c_bus();
+	rt_mutex_unlock(&adapter->bus_lock);
+}
+
+static const struct i2c_lock_operations i2c_dw_psp_lock_ops = {
+	.lock_bus = i2c_adapter_dw_psp_lock_bus,
+	.trylock_bus = i2c_adapter_dw_psp_trylock_bus,
+	.unlock_bus = i2c_adapter_dw_psp_unlock_bus,
+};
+
+int i2c_dw_amdpsp_probe_lock_support(struct dw_i2c_dev *dev)
+{
+	int ret;
+
+	if (!dev)
+		return -ENODEV;
+
+	if (!(dev->flags & ARBITRATION_SEMAPHORE))
+		return -ENODEV;
+
+	/* Allow to bind only one instance of a driver */
+	if (psp_i2c_dev)
+		return -EEXIST;
+
+	psp_i2c_dev = dev->dev;
+
+	ret = psp_mbox_probe();
+	if (ret)
+		return ret;
+
+	dev_info(psp_i2c_dev, "I2C bus managed by AMD PSP\n");
+
+	/*
+	 * Install global locking callbacks for adapter as well as internal i2c
+	 * controller locks.
+	 */
+	dev->adapter.lock_ops = &i2c_dw_psp_lock_ops;
+	dev->acquire_lock = psp_acquire_i2c_bus;
+	dev->release_lock = psp_release_i2c_bus;
+
+	return 0;
+}
+
+/* Unmap area used as a mailbox with PSP */
+void i2c_dw_amdpsp_remove_lock_support(struct dw_i2c_dev *dev)
+{
+	iounmap(mbox_iomem);
+}
diff --git a/drivers/i2c/busses/i2c-designware-baytrail.c b/drivers/i2c/busses/i2c-designware-baytrail.c
index c6a7a00e1d52..45774aa47c28 100644
--- a/drivers/i2c/busses/i2c-designware-baytrail.c
+++ b/drivers/i2c/busses/i2c-designware-baytrail.c
@@ -12,25 +12,25 @@
 
 #include "i2c-designware-core.h"
 
-int i2c_dw_probe_lock_support(struct dw_i2c_dev *dev)
+int i2c_dw_baytrail_probe_lock_support(struct dw_i2c_dev *dev)
 {
 	acpi_status status;
 	unsigned long long shared_host = 0;
 	acpi_handle handle;
 
-	if (!dev || !dev->dev)
-		return 0;
+	if (!dev)
+		return -ENODEV;
 
 	handle = ACPI_HANDLE(dev->dev);
 	if (!handle)
-		return 0;
+		return -ENODEV;
 
 	status = acpi_evaluate_integer(handle, "_SEM", NULL, &shared_host);
 	if (ACPI_FAILURE(status))
-		return 0;
+		return -ENODEV;
 
 	if (!shared_host)
-		return 0;
+		return -ENODEV;
 
 	if (!iosf_mbi_available())
 		return -EPROBE_DEFER;
diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index 4b26cba40139..1d65212fddbd 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -227,6 +227,8 @@ struct reset_control;
  * @hs_lcnt: high speed LCNT value
  * @acquire_lock: function to acquire a hardware lock on the bus
  * @release_lock: function to release a hardware lock on the bus
+ * @semaphore_idx: Index of table with semaphore type attached to the bus. It's
+ *	-1 if there is no semaphore.
  * @shared_with_punit: true if this bus is shared with the SoCs PUNIT
  * @disable: function to disable the controller
  * @disable_int: function to disable all interrupts
@@ -285,6 +287,7 @@ struct dw_i2c_dev {
 	u16			hs_lcnt;
 	int			(*acquire_lock)(void);
 	void			(*release_lock)(void);
+	int			semaphore_idx;
 	bool			shared_with_punit;
 	void			(*disable)(struct dw_i2c_dev *dev);
 	void			(*disable_int)(struct dw_i2c_dev *dev);
@@ -297,6 +300,7 @@ struct dw_i2c_dev {
 
 #define ACCESS_INTR_MASK	BIT(0)
 #define ACCESS_NO_IRQ_SUSPEND	BIT(1)
+#define ARBITRATION_SEMAPHORE	BIT(2)
 
 #define MODEL_MSCC_OCELOT	BIT(8)
 #define MODEL_BAIKAL_BT1	BIT(9)
@@ -310,6 +314,11 @@ struct dw_i2c_dev {
 #define AMD_UCSI_INTR_REG	0x474
 #define AMD_UCSI_INTR_EN	0xd
 
+struct i2c_dw_semaphore_callbacks {
+	int	(*probe)(struct dw_i2c_dev *dev);
+	void	(*remove)(struct dw_i2c_dev *dev);
+};
+
 int i2c_dw_init_regmap(struct dw_i2c_dev *dev);
 u32 i2c_dw_scl_hcnt(u32 ic_clk, u32 tSYMBOL, u32 tf, int cond, int offset);
 u32 i2c_dw_scl_lcnt(u32 ic_clk, u32 tLOW, u32 tf, int offset);
@@ -370,9 +379,12 @@ static inline void i2c_dw_configure(struct dw_i2c_dev *dev)
 }
 
 #if IS_ENABLED(CONFIG_I2C_DESIGNWARE_BAYTRAIL)
-extern int i2c_dw_probe_lock_support(struct dw_i2c_dev *dev);
-#else
-static inline int i2c_dw_probe_lock_support(struct dw_i2c_dev *dev) { return 0; }
+int i2c_dw_baytrail_probe_lock_support(struct dw_i2c_dev *dev);
+#endif
+
+#if IS_ENABLED(CONFIG_I2C_DESIGNWARE_AMDPSP)
+int i2c_dw_amdpsp_probe_lock_support(struct dw_i2c_dev *dev);
+void i2c_dw_amdpsp_remove_lock_support(struct dw_i2c_dev *dev);
 #endif
 
 int i2c_dw_validate_speed(struct dw_i2c_dev *dev);
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 2bd81abc86f6..9973ac894a51 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -50,6 +50,7 @@ static const struct acpi_device_id dw_i2c_acpi_match[] = {
 	{ "808622C1", ACCESS_NO_IRQ_SUSPEND },
 	{ "AMD0010", ACCESS_INTR_MASK },
 	{ "AMDI0010", ACCESS_INTR_MASK },
+	{ "AMDI0019", ACCESS_INTR_MASK | ARBITRATION_SEMAPHORE },
 	{ "AMDI0510", 0 },
 	{ "APMC0D0F", 0 },
 	{ "HISI02A1", 0 },
@@ -204,6 +205,63 @@ static const struct dmi_system_id dw_i2c_hwmon_class_dmi[] = {
 	{ } /* terminate list */
 };
 
+static const struct i2c_dw_semaphore_callbacks i2c_dw_semaphore_cb_table[] = {
+#ifdef CONFIG_I2C_DESIGNWARE_BAYTRAIL
+	{
+		.probe = i2c_dw_baytrail_probe_lock_support,
+	},
+#endif
+#ifdef CONFIG_I2C_DESIGNWARE_AMDPSP
+	{
+		.probe = i2c_dw_amdpsp_probe_lock_support,
+		.remove = i2c_dw_amdpsp_remove_lock_support,
+	},
+#endif
+	{}
+};
+
+static int i2c_dw_probe_lock_support(struct dw_i2c_dev *dev)
+{
+	const struct i2c_dw_semaphore_callbacks *ptr;
+	int i = 0;
+	int ret;
+
+	ptr = i2c_dw_semaphore_cb_table;
+
+	dev->semaphore_idx = -1;
+
+	while (ptr->probe) {
+		ret = ptr->probe(dev);
+		if (ret) {
+			/*
+			 * If there is no semaphore device attached to this
+			 * controller, we shouldn't abort general i2c_controller
+			 * probe.
+			 */
+			if (ret != -ENODEV)
+				return ret;
+
+			i++;
+			ptr++;
+			continue;
+		}
+
+		dev->semaphore_idx = i;
+		break;
+	}
+
+	return 0;
+}
+
+static void i2c_dw_remove_lock_support(struct dw_i2c_dev *dev)
+{
+	if (dev->semaphore_idx < 0)
+		return;
+
+	if (i2c_dw_semaphore_cb_table[dev->semaphore_idx].remove)
+		i2c_dw_semaphore_cb_table[dev->semaphore_idx].remove(dev);
+}
+
 static int dw_i2c_plat_probe(struct platform_device *pdev)
 {
 	struct i2c_adapter *adap;
@@ -334,6 +392,8 @@ static int dw_i2c_plat_remove(struct platform_device *pdev)
 	pm_runtime_put_sync(&pdev->dev);
 	dw_i2c_plat_pm_cleanup(dev);
 
+	i2c_dw_remove_lock_support(dev);
+
 	reset_control_assert(dev->rst);
 
 	return 0;
-- 
2.35.0.263.gb82422642f-goog

Re: [PATCH v4 2/2] i2c: designware: Add AMD PSP I2C bus support

[Andy Shevchenko]

On Tue, Feb 08, 2022 at 03:12:18PM +0100, Jan Dabros wrote:

...

I have noticed code duplication.

> +	status = psp_send_i2c_req(PSP_I2C_REQ_ACQUIRE);
> +	if (status) {
> +		if (status == -ETIMEDOUT)
> +			dev_err(psp_i2c_dev, "Timed out waiting for PSP to release I2C bus\n");
> +		else
> +			dev_err(psp_i2c_dev, "PSP communication error\n");
> +
> +		dev_err(psp_i2c_dev, "Assume i2c bus is for exclusive host usage\n");
> +		psp_i2c_mbox_fail = true;
> +		goto cleanup;
> +	}

> +	/* Send a release command to PSP */
> +	status = psp_send_i2c_req(PSP_I2C_REQ_RELEASE);
> +	if (status) {
> +		if (status == -ETIMEDOUT)
> +			dev_err(psp_i2c_dev, "Timed out waiting for PSP to acquire I2C bus\n");
> +		else
> +			dev_err(psp_i2c_dev, "PSP communication error\n");
> +
> +		dev_err(psp_i2c_dev, "Assume i2c bus is for exclusive host usage\n");
> +		psp_i2c_mbox_fail = true;
> +		goto cleanup;
> +	}

If you are going to update the series, consider to introduce a common helper.
Otherwise, consider a follow up.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v4 2/2] i2c: designware: Add AMD PSP I2C bus support

[Jan Dąbroś]

śr., 9 lut 2022 o 16:28 Andy Shevchenko
<andriy.shevchenko@linux.intel.com> napisał(a):
>
> On Tue, Feb 08, 2022 at 03:12:18PM +0100, Jan Dabros wrote:
>
> ...
>
> I have noticed code duplication.
>
> > +     status = psp_send_i2c_req(PSP_I2C_REQ_ACQUIRE);
> > +     if (status) {
> > +             if (status == -ETIMEDOUT)
> > +                     dev_err(psp_i2c_dev, "Timed out waiting for PSP to release I2C bus\n");
> > +             else
> > +                     dev_err(psp_i2c_dev, "PSP communication error\n");
> > +
> > +             dev_err(psp_i2c_dev, "Assume i2c bus is for exclusive host usage\n");
> > +             psp_i2c_mbox_fail = true;
> > +             goto cleanup;
> > +     }
>
> > +     /* Send a release command to PSP */
> > +     status = psp_send_i2c_req(PSP_I2C_REQ_RELEASE);
> > +     if (status) {
> > +             if (status == -ETIMEDOUT)
> > +                     dev_err(psp_i2c_dev, "Timed out waiting for PSP to acquire I2C bus\n");
> > +             else
> > +                     dev_err(psp_i2c_dev, "PSP communication error\n");
> > +
> > +             dev_err(psp_i2c_dev, "Assume i2c bus is for exclusive host usage\n");
> > +             psp_i2c_mbox_fail = true;
> > +             goto cleanup;
> > +     }
>
> If you are going to update the series, consider to introduce a common helper.
> Otherwise, consider a follow up.

Thanks for your comment. Since Jarkko is running some long-lasting
tests with v4 patchset, I would like to keep this as is for now (and
make a follow up commit). If there will be some additional comments
for v4 from him and will spin v5 - I will introduce a common helper
function then.

Best Regards,
Jan

Re: [PATCH v4 2/2] i2c: designware: Add AMD PSP I2C bus support

[Jarkko Nikula]

On 2/10/22 10:18, Jan Dąbroś wrote:
> śr., 9 lut 2022 o 16:28 Andy Shevchenko
> <andriy.shevchenko@linux.intel.com> napisał(a):
>>
>> On Tue, Feb 08, 2022 at 03:12:18PM +0100, Jan Dabros wrote:
>>
>> ...
>>
>> I have noticed code duplication.
>>
>>> +     status = psp_send_i2c_req(PSP_I2C_REQ_ACQUIRE);
>>> +     if (status) {
>>> +             if (status == -ETIMEDOUT)
>>> +                     dev_err(psp_i2c_dev, "Timed out waiting for PSP to release I2C bus\n");
>>> +             else
>>> +                     dev_err(psp_i2c_dev, "PSP communication error\n");
>>> +
>>> +             dev_err(psp_i2c_dev, "Assume i2c bus is for exclusive host usage\n");
>>> +             psp_i2c_mbox_fail = true;
>>> +             goto cleanup;
>>> +     }
>>
>>> +     /* Send a release command to PSP */
>>> +     status = psp_send_i2c_req(PSP_I2C_REQ_RELEASE);
>>> +     if (status) {
>>> +             if (status == -ETIMEDOUT)
>>> +                     dev_err(psp_i2c_dev, "Timed out waiting for PSP to acquire I2C bus\n");
>>> +             else
>>> +                     dev_err(psp_i2c_dev, "PSP communication error\n");
>>> +
>>> +             dev_err(psp_i2c_dev, "Assume i2c bus is for exclusive host usage\n");
>>> +             psp_i2c_mbox_fail = true;
>>> +             goto cleanup;
>>> +     }
>>
>> If you are going to update the series, consider to introduce a common helper.
>> Otherwise, consider a follow up.
> 
> Thanks for your comment. Since Jarkko is running some long-lasting
> tests with v4 patchset, I would like to keep this as is for now (and
> make a follow up commit). If there will be some additional comments
> for v4 from him and will spin v5 - I will introduce a common helper
> function then.
> 
Test run fine overnight, although I wasn't expecting this breaking 
Baytrail since patch is practically touching only semaphore detection at 
probe time on Baytrail. I'm up to you would you address Andy's comments 
as a follow up or as v5.

Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>

Re: [PATCH v4 2/2] i2c: designware: Add AMD PSP I2C bus support

[Jan Dąbroś]

Hi,

czw., 10 lut 2022 o 15:43 Jarkko Nikula
<jarkko.nikula@linux.intel.com> napisał(a):
>
> On 2/10/22 10:18, Jan Dąbroś wrote:
> > śr., 9 lut 2022 o 16:28 Andy Shevchenko
> > <andriy.shevchenko@linux.intel.com> napisał(a):
> >>
> >> On Tue, Feb 08, 2022 at 03:12:18PM +0100, Jan Dabros wrote:
> >>
> >> ...
> >>
> >> I have noticed code duplication.
> >>
> >>> +     status = psp_send_i2c_req(PSP_I2C_REQ_ACQUIRE);
> >>> +     if (status) {
> >>> +             if (status == -ETIMEDOUT)
> >>> +                     dev_err(psp_i2c_dev, "Timed out waiting for PSP to release I2C bus\n");
> >>> +             else
> >>> +                     dev_err(psp_i2c_dev, "PSP communication error\n");
> >>> +
> >>> +             dev_err(psp_i2c_dev, "Assume i2c bus is for exclusive host usage\n");
> >>> +             psp_i2c_mbox_fail = true;
> >>> +             goto cleanup;
> >>> +     }
> >>
> >>> +     /* Send a release command to PSP */
> >>> +     status = psp_send_i2c_req(PSP_I2C_REQ_RELEASE);
> >>> +     if (status) {
> >>> +             if (status == -ETIMEDOUT)
> >>> +                     dev_err(psp_i2c_dev, "Timed out waiting for PSP to acquire I2C bus\n");
> >>> +             else
> >>> +                     dev_err(psp_i2c_dev, "PSP communication error\n");
> >>> +
> >>> +             dev_err(psp_i2c_dev, "Assume i2c bus is for exclusive host usage\n");
> >>> +             psp_i2c_mbox_fail = true;
> >>> +             goto cleanup;
> >>> +     }
> >>
> >> If you are going to update the series, consider to introduce a common helper.
> >> Otherwise, consider a follow up.
> >
> > Thanks for your comment. Since Jarkko is running some long-lasting
> > tests with v4 patchset, I would like to keep this as is for now (and
> > make a follow up commit). If there will be some additional comments
> > for v4 from him and will spin v5 - I will introduce a common helper
> > function then.
> >
> Test run fine overnight, although I wasn't expecting this breaking
> Baytrail since patch is practically touching only semaphore detection at
> probe time on Baytrail. I'm up to you would you address Andy's comments
> as a follow up or as v5.
>
> Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
> Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>

Thanks!

If you don't mind I'd prefer a merge and a follow-up improvement on
top. Current version is tested and in case of breakage it would be
easier to track.

Best Regards,
Jan

Re: [PATCH v4 2/2] i2c: designware: Add AMD PSP I2C bus support

[Wolfram Sang]

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On Tue, Feb 08, 2022 at 03:12:18PM +0100, Jan Dabros wrote:
> Implement an I2C controller sharing mechanism between the host (kernel)
> and PSP co-processor on some platforms equipped with AMD Cezanne SoC.
> 
> On these platforms we need to implement "software" i2c arbitration.
> Default arbitration owner is PSP and kernel asks for acquire as well
> as inform about release of the i2c bus via mailbox mechanism.
> 
>             +---------+
>  <- ACQUIRE |         |
>   +---------|   CPU   |\
>   |         |         | \      +----------+  SDA

Applied to for-next, thanks! I fixed the following checkpatch warnings:

CHECK: Please don't use multiple blank lines
#232: FILE: drivers/i2c/busses/i2c-designware-amdpsp.c:92:
+
+

WARNING: braces {} are not necessary for single statement blocks
#361: FILE: drivers/i2c/busses/i2c-designware-amdpsp.c:221:
+	if (ret) {
+		goto cleanup;
+	}

Please also use checkpatch next time.


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Re: [PATCH v4 2/2] i2c: designware: Add AMD PSP I2C bus support

[Jan Dąbroś]

czw., 10 lut 2022 o 23:09 Wolfram Sang <wsa@kernel.org> napisał(a):
>
> On Tue, Feb 08, 2022 at 03:12:18PM +0100, Jan Dabros wrote:
> > Implement an I2C controller sharing mechanism between the host (kernel)
> > and PSP co-processor on some platforms equipped with AMD Cezanne SoC.
> >
> > On these platforms we need to implement "software" i2c arbitration.
> > Default arbitration owner is PSP and kernel asks for acquire as well
> > as inform about release of the i2c bus via mailbox mechanism.
> >
> >             +---------+
> >  <- ACQUIRE |         |
> >   +---------|   CPU   |\
> >   |         |         | \      +----------+  SDA
>
> Applied to for-next, thanks!

Thanks a lot!

> I fixed the following checkpatch warnings:
>
> CHECK: Please don't use multiple blank lines
> #232: FILE: drivers/i2c/busses/i2c-designware-amdpsp.c:92:
> +
> +
>
> WARNING: braces {} are not necessary for single statement blocks
> #361: FILE: drivers/i2c/busses/i2c-designware-amdpsp.c:221:
> +       if (ret) {
> +               goto cleanup;
> +       }
>
> Please also use checkpatch next time.

Ooops, sorry for this. Actually I used checkpatch till v3, but forgot
to run this on v4 where this change was introduced, my bad. Will
improve going forward :)

Best Regards,
Jan

Re: [PATCH v4 2/2] i2c: designware: Add AMD PSP I2C bus support

[Wolfram Sang]

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> Ooops, sorry for this. Actually I used checkpatch till v3, but forgot
> to run this on v4 where this change was introduced, my bad. Will
> improve going forward :)

No worries, happened to me as well. Thanks for your contribution!


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Re: [PATCH v4 0/2] i2c-designware: Add support for AMD PSP semaphore

[Jarkko Nikula]

On 2/8/22 16:12, Jan Dabros wrote:
> This patchset comprises support for new i2c-designware controller setup on some
> AMD Cezanne SoCs, where x86 is sharing i2c bus with PSP. PSP uses the same
> controller and acts as an i2c arbitrator there (x86 is leasing bus from it).
> 
> First commit aims to improve generic i2c-designware code by adding extra locking
> on probe() and disable() paths. I would like to ask someone with access to
> boards which use Intel BayTrail(CONFIG_I2C_DESIGNWARE_BAYTRAIL) to verify
> behavior of my changes on such setup.
> 
I'm going to run overnight with both patches a test case that used to 
cause some activity on a shared I2C bus on Baytrail based MRD 7 tablet. 
Test below used to trigger system hang after a few hours - days before 
some PUNIT - graphics related issue was fixed a few years ago:

#!/bin/sh
X &
export DISPLAY=:0
sleep 2
xclock -update 30 -digital -geometry 500x50+1+1027 &
xload -update 60 -bg black -hl red -fg green -geometry 1916x250+1+774 &
sleep 1
xsetroot -solid red
xset s noblank s off -dpms
glxgears >/dev/null &
while :; do acpi -b; sleep 1.2; done

Re: [PATCH v4 0/2] i2c-designware: Add support for AMD PSP semaphore

[Jan Dąbroś]

śr., 9 lut 2022 o 16:11 Jarkko Nikula <jarkko.nikula@linux.intel.com>
napisał(a):
>
> On 2/8/22 16:12, Jan Dabros wrote:
> > This patchset comprises support for new i2c-designware controller setup on some
> > AMD Cezanne SoCs, where x86 is sharing i2c bus with PSP. PSP uses the same
> > controller and acts as an i2c arbitrator there (x86 is leasing bus from it).
> >
> > First commit aims to improve generic i2c-designware code by adding extra locking
> > on probe() and disable() paths. I would like to ask someone with access to
> > boards which use Intel BayTrail(CONFIG_I2C_DESIGNWARE_BAYTRAIL) to verify
> > behavior of my changes on such setup.
> >
> I'm going to run overnight with both patches a test case that used to
> cause some activity on a shared I2C bus on Baytrail based MRD 7 tablet.
> Test below used to trigger system hang after a few hours - days before
> some PUNIT - graphics related issue was fixed a few years ago:
>
> #!/bin/sh
> X &
> export DISPLAY=:0
> sleep 2
> xclock -update 30 -digital -geometry 500x50+1+1027 &
> xload -update 60 -bg black -hl red -fg green -geometry 1916x250+1+774 &
> sleep 1
> xsetroot -solid red
> xset s noblank s off -dpms
> glxgears >/dev/null &
> while :; do acpi -b; sleep 1.2; done

Thanks, looking forward to the results.

Best Regards,
Jan