[PATCH v5] hwmon: (pmbus) Add support for MPS MP2949A

[PATCH v5] hwmon: (pmbus) Add support for MPS MP2949A

[ainux.wang]

From: "Ainux.Wang" <ainux.wang@gmail.com>

Add support for MP2949A device from Monolithic Power Systems, Inc. (MPS).
This is a triple-loop, digital, multi-phase controller.
This device:
- Supports up to three power rail.
- Provides 6 pulse-width modulations (PWMs), and can be configured up
  to 6-phase operation for Rail A , up to 2-phase operation for Rail B
  and up to 1-phase operation for Rail C.
- The PMBus registers are distributed into three pages: Page 0, Page 1,
  Page 2. Page 0 contains the registers for Rail A and most of the common
  settings for all of the rails. Page 1 contains register information for
  Rail B. Page 2 contains register information for Rail C.
- The MP2949A supports both 5mV VID step and 10mv VID step for IMVP8 and
  IMVP9.

Signed-off-by: Ainux.Wang <ainux.wang@gmail.com>
---
v5:
- Moved change log to right here.
v4:
- Removed mp2949a_read_byte_data().
- Added space before and after '-' and fixed a bug that is '~' on line 35.

v3:
- Added change log here.
- Errors in the document have been modified.
- Fixed PMBUS_VOUT_MODE to MP2949A_MFR_VR_CONFIG.
- Removed unnecessary vout_params and empty line.

v2:
- Reference has been added to Documentation/hwmon/index.rst.
- Droped 'vendor'.
- Removed change codes of the PMBus core and added mp2949a_identify()
  and mp2949a_read_byte_data() to this driver.

v1:
- Add support for MPS MP2949A.
 Documentation/hwmon/index.rst   |   1 +
 Documentation/hwmon/mp2949a.rst |  44 ++++++++++++++
 drivers/hwmon/pmbus/Kconfig     |   9 +++
 drivers/hwmon/pmbus/Makefile    |   1 +
 drivers/hwmon/pmbus/mp2949a.c   | 102 ++++++++++++++++++++++++++++++++
 5 files changed, 157 insertions(+)
 create mode 100644 Documentation/hwmon/mp2949a.rst
 create mode 100644 drivers/hwmon/pmbus/mp2949a.c

diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index 9ed60fa84cbe..56aac3b1678d 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -137,6 +137,7 @@ Hardware Monitoring Kernel Drivers
    mcp3021
    menf21bmc
    mlxreg-fan
+   mp2949a
    mp2975
    nct6683
    nct6775
diff --git a/Documentation/hwmon/mp2949a.rst b/Documentation/hwmon/mp2949a.rst
new file mode 100644
index 000000000000..0235dec70f63
--- /dev/null
+++ b/Documentation/hwmon/mp2949a.rst
@@ -0,0 +1,44 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver mp2949a
+====================
+
+Supported chips:
+
+  * MPS MP2949A
+
+    Prefix: 'mp2949a'
+
+Author:
+
+	Ainux Wang <ainux.wang@gmail.com>
+
+Description
+-----------
+
+This driver implements support for Monolithic Power Systems, Inc. (MPS)
+triple-loop, digital, multi-phase controller MP2949A.
+
+This device:
+
+- Supports up to three power rails.
+- Provides 6 pulse-width modulations (PWMs), and can be configured for
+  to 6-phase operation for Rail A , up to 2-phase operation for Rail B,
+  and up to 1-phase operation for Rail C.
+- The PMBus registers are distributed into three pages: Page 0, Page 1,
+  Page 2. Page 0 contains the registers for Rail A and most of the common
+  settings for all of the rails. Page 1 contains register information for
+  Rail B. Page 2 contains register information for Rail C.
+- The MP2949A supports both 5mV VID step and 10mv VID step for IMVP8 and
+  IMVP9.
+
+Device supports:
+
+- SVID interface.
+- PMBus rev 1.2 interface.
+
+Device supports direct format for reading output power.
+Device supports linear format for reading input voltage, output current,
+and temperature.
+Device supports VID for reading output voltage.
+The below VID modes are supported: VR12, VR13, IMVP8, IMVP9.
diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
index 37a5c39784fa..b1344b265976 100644
--- a/drivers/hwmon/pmbus/Kconfig
+++ b/drivers/hwmon/pmbus/Kconfig
@@ -248,6 +248,15 @@ config SENSORS_MAX8688
 	  This driver can also be built as a module. If so, the module will
 	  be called max8688.
 
+config SENSORS_MP2949A
+	tristate "MPS MP2949A"
+	help
+	  If you say yes here you get hardware monitoring support for MPS
+	  MP2949A Triple Loop Digital Multi-Phase Controller.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called mp2949a.
+
 config SENSORS_MP2975
 	tristate "MPS MP2975"
 	help
diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
index f8dcc27cd56a..bfb55ab12da1 100644
--- a/drivers/hwmon/pmbus/Makefile
+++ b/drivers/hwmon/pmbus/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_SENSORS_MAX20751)	+= max20751.o
 obj-$(CONFIG_SENSORS_MAX31785)	+= max31785.o
 obj-$(CONFIG_SENSORS_MAX34440)	+= max34440.o
 obj-$(CONFIG_SENSORS_MAX8688)	+= max8688.o
+obj-$(CONFIG_SENSORS_MP2949A)	+= mp2949a.o
 obj-$(CONFIG_SENSORS_MP2975)	+= mp2975.o
 obj-$(CONFIG_SENSORS_PM6764TR)	+= pm6764tr.o
 obj-$(CONFIG_SENSORS_PXE1610)	+= pxe1610.o
diff --git a/drivers/hwmon/pmbus/mp2949a.c b/drivers/hwmon/pmbus/mp2949a.c
new file mode 100644
index 000000000000..d1f36c008e58
--- /dev/null
+++ b/drivers/hwmon/pmbus/mp2949a.c
@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Hardware monitoring driver for Monolithic Power Systems MP2949A
+ *
+ * Copyright (c) 2021 Lemote Technologies. All rights reserved.
+ * Copyright (c) 2021 Ainux <ainux.wang@gmail.com>
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include "pmbus.h"
+
+#define MP2949A_PAGE_NUM		3
+
+#define MP2949A_MFR_VR_CONFIG	0xE4
+
+static int mp2949a_identify(struct i2c_client *client,
+			    struct pmbus_driver_info *info)
+{
+	int i, ret;
+
+	for (i = 0; i < MP2949A_PAGE_NUM; i++) {
+		ret = pmbus_read_byte_data(client, i, MP2949A_MFR_VR_CONFIG);
+		if (ret < 0)
+			return ret;
+
+		/*
+		 * Rail A bit 5, Rail B bit 4, Rail C bit 3.
+		 * 1'b1: 5mV  (vr12/imvp8)
+		 * 1'b0: 10mv (imvp9)
+		 */
+		info->vrm_version[i] = (ret & BIT(5 - i)) ? vr12 : imvp9;
+	}
+
+	return 0;
+}
+
+static struct pmbus_driver_info mp2949a_info = {
+	.pages = MP2949A_PAGE_NUM,
+	.format[PSC_VOLTAGE_IN] = linear,
+	.format[PSC_VOLTAGE_OUT] = vid,
+	.format[PSC_CURRENT_OUT] = linear,
+	.format[PSC_TEMPERATURE] = linear,
+	.format[PSC_POWER] = direct,
+	.m[PSC_POWER] = 1,
+	.b[PSC_POWER] = 0,
+	.R[PSC_POWER] = 0,
+	.func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT |
+		PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
+		PMBUS_HAVE_TEMP | PMBUS_HAVE_POUT,
+	.func[1] = PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT |
+		PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
+		PMBUS_HAVE_POUT,
+	.func[2] = PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT |
+		PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
+		PMBUS_HAVE_POUT,
+	.identify = mp2949a_identify,
+};
+
+static int mp2949a_probe(struct i2c_client *client,
+			  const struct i2c_device_id *id)
+{
+	struct pmbus_driver_info *info;
+
+	info = devm_kmemdup(&client->dev, &mp2949a_info, sizeof(*info),
+			    GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	return pmbus_do_probe(client, info);
+}
+
+static const struct i2c_device_id mp2949a_id[] = {
+	{"mp2949a", 0},
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, mp2949a_id);
+
+static const struct of_device_id mp2949a_of_match[] = {
+	{.compatible = "mps,mp2949a"},
+	{}
+};
+MODULE_DEVICE_TABLE(of, mp2949a_of_match);
+
+static struct i2c_driver mp2949a_driver = {
+	.driver = {
+		.name = "mp2949a",
+		.of_match_table = of_match_ptr(mp2949a_of_match),
+	},
+	.probe = mp2949a_probe,
+	.id_table = mp2949a_id,
+};
+
+module_i2c_driver(mp2949a_driver);
+
+MODULE_AUTHOR("Ainux <ainux.wang@gmail.com>");
+MODULE_DESCRIPTION("PMBus driver for Monolithic Power Systems MP2949A");
+MODULE_LICENSE("GPL");
-- 
2.18.1

Re: [PATCH v5] hwmon: (pmbus) Add support for MPS MP2949A

[Guenter Roeck]

On Wed, Jun 23, 2021 at 08:54:26AM +0800, ainux.wang@gmail.com wrote:
> From: "Ainux.Wang" <ainux.wang@gmail.com>
> 
> Add support for MP2949A device from Monolithic Power Systems, Inc. (MPS).
> This is a triple-loop, digital, multi-phase controller.
> This device:
> - Supports up to three power rail.
> - Provides 6 pulse-width modulations (PWMs), and can be configured up
>   to 6-phase operation for Rail A , up to 2-phase operation for Rail B
>   and up to 1-phase operation for Rail C.
> - The PMBus registers are distributed into three pages: Page 0, Page 1,
>   Page 2. Page 0 contains the registers for Rail A and most of the common
>   settings for all of the rails. Page 1 contains register information for
>   Rail B. Page 2 contains register information for Rail C.
> - The MP2949A supports both 5mV VID step and 10mv VID step for IMVP8 and
>   IMVP9.
> 
> Signed-off-by: Ainux.Wang <ainux.wang@gmail.com>
> ---
> v5:
> - Moved change log to right here.
> v4:
> - Removed mp2949a_read_byte_data().

Your other question left me confused. I had previously asked to provide
a rationale for filtering out the PMBUS_VOUT_MODE command, and I had
stated that "the chip does not support it" is not a valid reason. However,
"the chip does not support it but does not report an error when reading
it" _is_ a valid reason. So what happens when the PMBus core reads
PMBUS_VOUT_MODE ? Does the chip return an error, or some random data ?

Thanks,
Guenter

> - Added space before and after '-' and fixed a bug that is '~' on line 35.
> 
> v3:
> - Added change log here.
> - Errors in the document have been modified.
> - Fixed PMBUS_VOUT_MODE to MP2949A_MFR_VR_CONFIG.
> - Removed unnecessary vout_params and empty line.
> 
> v2:
> - Reference has been added to Documentation/hwmon/index.rst.
> - Droped 'vendor'.
> - Removed change codes of the PMBus core and added mp2949a_identify()
>   and mp2949a_read_byte_data() to this driver.
> 
> v1:
> - Add support for MPS MP2949A.
>  Documentation/hwmon/index.rst   |   1 +
>  Documentation/hwmon/mp2949a.rst |  44 ++++++++++++++
>  drivers/hwmon/pmbus/Kconfig     |   9 +++
>  drivers/hwmon/pmbus/Makefile    |   1 +
>  drivers/hwmon/pmbus/mp2949a.c   | 102 ++++++++++++++++++++++++++++++++
>  5 files changed, 157 insertions(+)
>  create mode 100644 Documentation/hwmon/mp2949a.rst
>  create mode 100644 drivers/hwmon/pmbus/mp2949a.c
> 
> diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> index 9ed60fa84cbe..56aac3b1678d 100644
> --- a/Documentation/hwmon/index.rst
> +++ b/Documentation/hwmon/index.rst
> @@ -137,6 +137,7 @@ Hardware Monitoring Kernel Drivers
>     mcp3021
>     menf21bmc
>     mlxreg-fan
> +   mp2949a
>     mp2975
>     nct6683
>     nct6775
> diff --git a/Documentation/hwmon/mp2949a.rst b/Documentation/hwmon/mp2949a.rst
> new file mode 100644
> index 000000000000..0235dec70f63
> --- /dev/null
> +++ b/Documentation/hwmon/mp2949a.rst
> @@ -0,0 +1,44 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +Kernel driver mp2949a
> +====================
> +
> +Supported chips:
> +
> +  * MPS MP2949A
> +
> +    Prefix: 'mp2949a'
> +
> +Author:
> +
> +	Ainux Wang <ainux.wang@gmail.com>
> +
> +Description
> +-----------
> +
> +This driver implements support for Monolithic Power Systems, Inc. (MPS)
> +triple-loop, digital, multi-phase controller MP2949A.
> +
> +This device:
> +
> +- Supports up to three power rails.
> +- Provides 6 pulse-width modulations (PWMs), and can be configured for
> +  to 6-phase operation for Rail A , up to 2-phase operation for Rail B,
> +  and up to 1-phase operation for Rail C.
> +- The PMBus registers are distributed into three pages: Page 0, Page 1,
> +  Page 2. Page 0 contains the registers for Rail A and most of the common
> +  settings for all of the rails. Page 1 contains register information for
> +  Rail B. Page 2 contains register information for Rail C.
> +- The MP2949A supports both 5mV VID step and 10mv VID step for IMVP8 and
> +  IMVP9.
> +
> +Device supports:
> +
> +- SVID interface.
> +- PMBus rev 1.2 interface.
> +
> +Device supports direct format for reading output power.
> +Device supports linear format for reading input voltage, output current,
> +and temperature.
> +Device supports VID for reading output voltage.
> +The below VID modes are supported: VR12, VR13, IMVP8, IMVP9.
> diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
> index 37a5c39784fa..b1344b265976 100644
> --- a/drivers/hwmon/pmbus/Kconfig
> +++ b/drivers/hwmon/pmbus/Kconfig
> @@ -248,6 +248,15 @@ config SENSORS_MAX8688
>  	  This driver can also be built as a module. If so, the module will
>  	  be called max8688.
>  
> +config SENSORS_MP2949A
> +	tristate "MPS MP2949A"
> +	help
> +	  If you say yes here you get hardware monitoring support for MPS
> +	  MP2949A Triple Loop Digital Multi-Phase Controller.
> +
> +	  This driver can also be built as a module. If so, the module will
> +	  be called mp2949a.
> +
>  config SENSORS_MP2975
>  	tristate "MPS MP2975"
>  	help
> diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
> index f8dcc27cd56a..bfb55ab12da1 100644
> --- a/drivers/hwmon/pmbus/Makefile
> +++ b/drivers/hwmon/pmbus/Makefile
> @@ -28,6 +28,7 @@ obj-$(CONFIG_SENSORS_MAX20751)	+= max20751.o
>  obj-$(CONFIG_SENSORS_MAX31785)	+= max31785.o
>  obj-$(CONFIG_SENSORS_MAX34440)	+= max34440.o
>  obj-$(CONFIG_SENSORS_MAX8688)	+= max8688.o
> +obj-$(CONFIG_SENSORS_MP2949A)	+= mp2949a.o
>  obj-$(CONFIG_SENSORS_MP2975)	+= mp2975.o
>  obj-$(CONFIG_SENSORS_PM6764TR)	+= pm6764tr.o
>  obj-$(CONFIG_SENSORS_PXE1610)	+= pxe1610.o
> diff --git a/drivers/hwmon/pmbus/mp2949a.c b/drivers/hwmon/pmbus/mp2949a.c
> new file mode 100644
> index 000000000000..d1f36c008e58
> --- /dev/null
> +++ b/drivers/hwmon/pmbus/mp2949a.c
> @@ -0,0 +1,102 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Hardware monitoring driver for Monolithic Power Systems MP2949A
> + *
> + * Copyright (c) 2021 Lemote Technologies. All rights reserved.
> + * Copyright (c) 2021 Ainux <ainux.wang@gmail.com>
> + */
> +
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include "pmbus.h"
> +
> +#define MP2949A_PAGE_NUM		3
> +
> +#define MP2949A_MFR_VR_CONFIG	0xE4
> +
> +static int mp2949a_identify(struct i2c_client *client,
> +			    struct pmbus_driver_info *info)
> +{
> +	int i, ret;
> +
> +	for (i = 0; i < MP2949A_PAGE_NUM; i++) {
> +		ret = pmbus_read_byte_data(client, i, MP2949A_MFR_VR_CONFIG);
> +		if (ret < 0)
> +			return ret;
> +
> +		/*
> +		 * Rail A bit 5, Rail B bit 4, Rail C bit 3.
> +		 * 1'b1: 5mV  (vr12/imvp8)
> +		 * 1'b0: 10mv (imvp9)
> +		 */
> +		info->vrm_version[i] = (ret & BIT(5 - i)) ? vr12 : imvp9;
> +	}
> +
> +	return 0;
> +}
> +
> +static struct pmbus_driver_info mp2949a_info = {
> +	.pages = MP2949A_PAGE_NUM,
> +	.format[PSC_VOLTAGE_IN] = linear,
> +	.format[PSC_VOLTAGE_OUT] = vid,
> +	.format[PSC_CURRENT_OUT] = linear,
> +	.format[PSC_TEMPERATURE] = linear,
> +	.format[PSC_POWER] = direct,
> +	.m[PSC_POWER] = 1,
> +	.b[PSC_POWER] = 0,
> +	.R[PSC_POWER] = 0,
> +	.func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT |
> +		PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
> +		PMBUS_HAVE_TEMP | PMBUS_HAVE_POUT,
> +	.func[1] = PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT |
> +		PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
> +		PMBUS_HAVE_POUT,
> +	.func[2] = PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT |
> +		PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
> +		PMBUS_HAVE_POUT,
> +	.identify = mp2949a_identify,
> +};
> +
> +static int mp2949a_probe(struct i2c_client *client,
> +			  const struct i2c_device_id *id)
> +{
> +	struct pmbus_driver_info *info;
> +
> +	info = devm_kmemdup(&client->dev, &mp2949a_info, sizeof(*info),
> +			    GFP_KERNEL);
> +	if (!info)
> +		return -ENOMEM;
> +
> +	return pmbus_do_probe(client, info);
> +}
> +
> +static const struct i2c_device_id mp2949a_id[] = {
> +	{"mp2949a", 0},
> +	{}
> +};
> +
> +MODULE_DEVICE_TABLE(i2c, mp2949a_id);
> +
> +static const struct of_device_id mp2949a_of_match[] = {
> +	{.compatible = "mps,mp2949a"},
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, mp2949a_of_match);
> +
> +static struct i2c_driver mp2949a_driver = {
> +	.driver = {
> +		.name = "mp2949a",
> +		.of_match_table = of_match_ptr(mp2949a_of_match),
> +	},
> +	.probe = mp2949a_probe,
> +	.id_table = mp2949a_id,
> +};
> +
> +module_i2c_driver(mp2949a_driver);
> +
> +MODULE_AUTHOR("Ainux <ainux.wang@gmail.com>");
> +MODULE_DESCRIPTION("PMBus driver for Monolithic Power Systems MP2949A");
> +MODULE_LICENSE("GPL");

Re: [PATCH v5] hwmon: (pmbus) Add support for MPS MP2949A

[Guenter Roeck]

On 6/24/21 6:17 AM, Guenter Roeck wrote:
> On Wed, Jun 23, 2021 at 08:54:26AM +0800, ainux.wang@gmail.com wrote:
>> From: "Ainux.Wang" <ainux.wang@gmail.com>
>>
>> Add support for MP2949A device from Monolithic Power Systems, Inc. (MPS).
>> This is a triple-loop, digital, multi-phase controller.
>> This device:
>> - Supports up to three power rail.
>> - Provides 6 pulse-width modulations (PWMs), and can be configured up
>>    to 6-phase operation for Rail A , up to 2-phase operation for Rail B
>>    and up to 1-phase operation for Rail C.
>> - The PMBus registers are distributed into three pages: Page 0, Page 1,
>>    Page 2. Page 0 contains the registers for Rail A and most of the common
>>    settings for all of the rails. Page 1 contains register information for
>>    Rail B. Page 2 contains register information for Rail C.
>> - The MP2949A supports both 5mV VID step and 10mv VID step for IMVP8 and
>>    IMVP9.
>>
>> Signed-off-by: Ainux.Wang <ainux.wang@gmail.com>
>> ---
>> v5:
>> - Moved change log to right here.
>> v4:
>> - Removed mp2949a_read_byte_data().
> 
> Your other question left me confused. I had previously asked to provide
> a rationale for filtering out the PMBUS_VOUT_MODE command, and I had
> stated that "the chip does not support it" is not a valid reason. However,
> "the chip does not support it but does not report an error when reading
> it" _is_ a valid reason. So what happens when the PMBus core reads
> PMBUS_VOUT_MODE ? Does the chip return an error, or some random data ?
> 

Still waiting for a reply.

Guenter

Re: [PATCH v5] hwmon: (pmbus) Add support for MPS MP2949A

[Ainux Wang]

On Thu, 24 Jun 2021 at 21:17, Guenter Roeck <linux@roeck-us.net> wrote:
>
> On Wed, Jun 23, 2021 at 08:54:26AM +0800, ainux.wang@gmail.com wrote:
> > From: "Ainux.Wang" <ainux.wang@gmail.com>
> >
> > Add support for MP2949A device from Monolithic Power Systems, Inc. (MPS).
> > This is a triple-loop, digital, multi-phase controller.
> > This device:
> > - Supports up to three power rail.
> > - Provides 6 pulse-width modulations (PWMs), and can be configured up
> >   to 6-phase operation for Rail A , up to 2-phase operation for Rail B
> >   and up to 1-phase operation for Rail C.
> > - The PMBus registers are distributed into three pages: Page 0, Page 1,
> >   Page 2. Page 0 contains the registers for Rail A and most of the common
> >   settings for all of the rails. Page 1 contains register information for
> >   Rail B. Page 2 contains register information for Rail C.
> > - The MP2949A supports both 5mV VID step and 10mv VID step for IMVP8 and
> >   IMVP9.
> >
> > Signed-off-by: Ainux.Wang <ainux.wang@gmail.com>
> > ---
> > v5:
> > - Moved change log to right here.
> > v4:
> > - Removed mp2949a_read_byte_data().
>
> Your other question left me confused. I had previously asked to provide
> a rationale for filtering out the PMBUS_VOUT_MODE command, and I had
> stated that "the chip does not support it" is not a valid reason. However,
> "the chip does not support it but does not report an error when reading
> it" _is_ a valid reason. So what happens when the PMBus core reads
> PMBUS_VOUT_MODE ? Does the chip return an error, or some random data ?
>
> Thanks,
> Guenter
>
Hi, Guenter

I have not been clear about the cause of this problem that
"the chip does not support it is not a valid reason".

However, i have added some "printk", i found the chip will return some
random data,
when the PMbus core reads PMBUS_STATUS and PMBUS_VOUT_MODE.

So, I do not known what should i do, when the PMbus core reads PMBUS_STATUS.
and i have knwon that use "This chip do not support the VOUT_MODE command,
the chip does not support it but return some random data when reading
" instead of
"
               /*
                * This chip do not support the VOUT_MODE command.
                * There is not VOUT_MODE command in MP2949A datasheet P29~P31.
                * So this is EINVAL in here.
               */
"
Now, there is only one question left, what should the PMbus do, the
chip return random data,
when it reads PMBUS_STATUS by i2c_smbus_read_word_data() or
i2c_smbus_read_byte_data()?
Can the PMbus core use  pmbus_read_status_byte() and
pmbus_read_status_word() instead of
i2c_smbus_read_byte_data() and i2c_smbus_read_word_data() ?

Best regards,
Ainux Wang.
> > - Added space before and after '-' and fixed a bug that is '~' on line 35.
> >
> > v3:
> > - Added change log here.
> > - Errors in the document have been modified.
> > - Fixed PMBUS_VOUT_MODE to MP2949A_MFR_VR_CONFIG.
> > - Removed unnecessary vout_params and empty line.
> >
> > v2:
> > - Reference has been added to Documentation/hwmon/index.rst.
> > - Droped 'vendor'.
> > - Removed change codes of the PMBus core and added mp2949a_identify()
> >   and mp2949a_read_byte_data() to this driver.
> >
> > v1:
> > - Add support for MPS MP2949A.
> >  Documentation/hwmon/index.rst   |   1 +
> >  Documentation/hwmon/mp2949a.rst |  44 ++++++++++++++
> >  drivers/hwmon/pmbus/Kconfig     |   9 +++
> >  drivers/hwmon/pmbus/Makefile    |   1 +
> >  drivers/hwmon/pmbus/mp2949a.c   | 102 ++++++++++++++++++++++++++++++++
> >  5 files changed, 157 insertions(+)
> >  create mode 100644 Documentation/hwmon/mp2949a.rst
> >  create mode 100644 drivers/hwmon/pmbus/mp2949a.c
> >
> > diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> > index 9ed60fa84cbe..56aac3b1678d 100644
> > --- a/Documentation/hwmon/index.rst
> > +++ b/Documentation/hwmon/index.rst
> > @@ -137,6 +137,7 @@ Hardware Monitoring Kernel Drivers
> >     mcp3021
> >     menf21bmc
> >     mlxreg-fan
> > +   mp2949a
> >     mp2975
> >     nct6683
> >     nct6775
> > diff --git a/Documentation/hwmon/mp2949a.rst b/Documentation/hwmon/mp2949a.rst
> > new file mode 100644
> > index 000000000000..0235dec70f63
> > --- /dev/null
> > +++ b/Documentation/hwmon/mp2949a.rst
> > @@ -0,0 +1,44 @@
> > +.. SPDX-License-Identifier: GPL-2.0
> > +
> > +Kernel driver mp2949a
> > +====================
> > +
> > +Supported chips:
> > +
> > +  * MPS MP2949A
> > +
> > +    Prefix: 'mp2949a'
> > +
> > +Author:
> > +
> > +     Ainux Wang <ainux.wang@gmail.com>
> > +
> > +Description
> > +-----------
> > +
> > +This driver implements support for Monolithic Power Systems, Inc. (MPS)
> > +triple-loop, digital, multi-phase controller MP2949A.
> > +
> > +This device:
> > +
> > +- Supports up to three power rails.
> > +- Provides 6 pulse-width modulations (PWMs), and can be configured for
> > +  to 6-phase operation for Rail A , up to 2-phase operation for Rail B,
> > +  and up to 1-phase operation for Rail C.
> > +- The PMBus registers are distributed into three pages: Page 0, Page 1,
> > +  Page 2. Page 0 contains the registers for Rail A and most of the common
> > +  settings for all of the rails. Page 1 contains register information for
> > +  Rail B. Page 2 contains register information for Rail C.
> > +- The MP2949A supports both 5mV VID step and 10mv VID step for IMVP8 and
> > +  IMVP9.
> > +
> > +Device supports:
> > +
> > +- SVID interface.
> > +- PMBus rev 1.2 interface.
> > +
> > +Device supports direct format for reading output power.
> > +Device supports linear format for reading input voltage, output current,
> > +and temperature.
> > +Device supports VID for reading output voltage.
> > +The below VID modes are supported: VR12, VR13, IMVP8, IMVP9.
> > diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
> > index 37a5c39784fa..b1344b265976 100644
> > --- a/drivers/hwmon/pmbus/Kconfig
> > +++ b/drivers/hwmon/pmbus/Kconfig
> > @@ -248,6 +248,15 @@ config SENSORS_MAX8688
> >         This driver can also be built as a module. If so, the module will
> >         be called max8688.
> >
> > +config SENSORS_MP2949A
> > +     tristate "MPS MP2949A"
> > +     help
> > +       If you say yes here you get hardware monitoring support for MPS
> > +       MP2949A Triple Loop Digital Multi-Phase Controller.
> > +
> > +       This driver can also be built as a module. If so, the module will
> > +       be called mp2949a.
> > +
> >  config SENSORS_MP2975
> >       tristate "MPS MP2975"
> >       help
> > diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
> > index f8dcc27cd56a..bfb55ab12da1 100644
> > --- a/drivers/hwmon/pmbus/Makefile
> > +++ b/drivers/hwmon/pmbus/Makefile
> > @@ -28,6 +28,7 @@ obj-$(CONFIG_SENSORS_MAX20751)      += max20751.o
> >  obj-$(CONFIG_SENSORS_MAX31785)       += max31785.o
> >  obj-$(CONFIG_SENSORS_MAX34440)       += max34440.o
> >  obj-$(CONFIG_SENSORS_MAX8688)        += max8688.o
> > +obj-$(CONFIG_SENSORS_MP2949A)        += mp2949a.o
> >  obj-$(CONFIG_SENSORS_MP2975) += mp2975.o
> >  obj-$(CONFIG_SENSORS_PM6764TR)       += pm6764tr.o
> >  obj-$(CONFIG_SENSORS_PXE1610)        += pxe1610.o
> > diff --git a/drivers/hwmon/pmbus/mp2949a.c b/drivers/hwmon/pmbus/mp2949a.c
> > new file mode 100644
> > index 000000000000..d1f36c008e58
> > --- /dev/null
> > +++ b/drivers/hwmon/pmbus/mp2949a.c
> > @@ -0,0 +1,102 @@
> > +// SPDX-License-Identifier: GPL-2.0-or-later
> > +/*
> > + * Hardware monitoring driver for Monolithic Power Systems MP2949A
> > + *
> > + * Copyright (c) 2021 Lemote Technologies. All rights reserved.
> > + * Copyright (c) 2021 Ainux <ainux.wang@gmail.com>
> > + */
> > +
> > +#include <linux/err.h>
> > +#include <linux/i2c.h>
> > +#include <linux/init.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include "pmbus.h"
> > +
> > +#define MP2949A_PAGE_NUM             3
> > +
> > +#define MP2949A_MFR_VR_CONFIG        0xE4
> > +
> > +static int mp2949a_identify(struct i2c_client *client,
> > +                         struct pmbus_driver_info *info)
> > +{
> > +     int i, ret;
> > +
> > +     for (i = 0; i < MP2949A_PAGE_NUM; i++) {
> > +             ret = pmbus_read_byte_data(client, i, MP2949A_MFR_VR_CONFIG);
> > +             if (ret < 0)
> > +                     return ret;
> > +
> > +             /*
> > +              * Rail A bit 5, Rail B bit 4, Rail C bit 3.
> > +              * 1'b1: 5mV  (vr12/imvp8)
> > +              * 1'b0: 10mv (imvp9)
> > +              */
> > +             info->vrm_version[i] = (ret & BIT(5 - i)) ? vr12 : imvp9;
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +static struct pmbus_driver_info mp2949a_info = {
> > +     .pages = MP2949A_PAGE_NUM,
> > +     .format[PSC_VOLTAGE_IN] = linear,
> > +     .format[PSC_VOLTAGE_OUT] = vid,
> > +     .format[PSC_CURRENT_OUT] = linear,
> > +     .format[PSC_TEMPERATURE] = linear,
> > +     .format[PSC_POWER] = direct,
> > +     .m[PSC_POWER] = 1,
> > +     .b[PSC_POWER] = 0,
> > +     .R[PSC_POWER] = 0,
> > +     .func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT |
> > +             PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
> > +             PMBUS_HAVE_TEMP | PMBUS_HAVE_POUT,
> > +     .func[1] = PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT |
> > +             PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
> > +             PMBUS_HAVE_POUT,
> > +     .func[2] = PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT |
> > +             PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
> > +             PMBUS_HAVE_POUT,
> > +     .identify = mp2949a_identify,
> > +};
> > +
> > +static int mp2949a_probe(struct i2c_client *client,
> > +                       const struct i2c_device_id *id)
> > +{
> > +     struct pmbus_driver_info *info;
> > +
> > +     info = devm_kmemdup(&client->dev, &mp2949a_info, sizeof(*info),
> > +                         GFP_KERNEL);
> > +     if (!info)
> > +             return -ENOMEM;
> > +
> > +     return pmbus_do_probe(client, info);
> > +}
> > +
> > +static const struct i2c_device_id mp2949a_id[] = {
> > +     {"mp2949a", 0},
> > +     {}
> > +};
> > +
> > +MODULE_DEVICE_TABLE(i2c, mp2949a_id);
> > +
> > +static const struct of_device_id mp2949a_of_match[] = {
> > +     {.compatible = "mps,mp2949a"},
> > +     {}
> > +};
> > +MODULE_DEVICE_TABLE(of, mp2949a_of_match);
> > +
> > +static struct i2c_driver mp2949a_driver = {
> > +     .driver = {
> > +             .name = "mp2949a",
> > +             .of_match_table = of_match_ptr(mp2949a_of_match),
> > +     },
> > +     .probe = mp2949a_probe,
> > +     .id_table = mp2949a_id,
> > +};
> > +
> > +module_i2c_driver(mp2949a_driver);
> > +
> > +MODULE_AUTHOR("Ainux <ainux.wang@gmail.com>");
> > +MODULE_DESCRIPTION("PMBus driver for Monolithic Power Systems MP2949A");
> > +MODULE_LICENSE("GPL");

Re: [PATCH v5] hwmon: (pmbus) Add support for MPS MP2949A

[Ainux Wang]

On Mon, 28 Jun 2021 at 21:38, Guenter Roeck <linux@roeck-us.net> wrote:
>
> On 6/24/21 6:17 AM, Guenter Roeck wrote:
> > On Wed, Jun 23, 2021 at 08:54:26AM +0800, ainux.wang@gmail.com wrote:
> >> From: "Ainux.Wang" <ainux.wang@gmail.com>
> >>
> >> Add support for MP2949A device from Monolithic Power Systems, Inc. (MPS).
> >> This is a triple-loop, digital, multi-phase controller.
> >> This device:
> >> - Supports up to three power rail.
> >> - Provides 6 pulse-width modulations (PWMs), and can be configured up
> >>    to 6-phase operation for Rail A , up to 2-phase operation for Rail B
> >>    and up to 1-phase operation for Rail C.
> >> - The PMBus registers are distributed into three pages: Page 0, Page 1,
> >>    Page 2. Page 0 contains the registers for Rail A and most of the common
> >>    settings for all of the rails. Page 1 contains register information for
> >>    Rail B. Page 2 contains register information for Rail C.
> >> - The MP2949A supports both 5mV VID step and 10mv VID step for IMVP8 and
> >>    IMVP9.
> >>
> >> Signed-off-by: Ainux.Wang <ainux.wang@gmail.com>
> >> ---
> >> v5:
> >> - Moved change log to right here.
> >> v4:
> >> - Removed mp2949a_read_byte_data().
> >
> > Your other question left me confused. I had previously asked to provide
> > a rationale for filtering out the PMBUS_VOUT_MODE command, and I had
> > stated that "the chip does not support it" is not a valid reason. However,
> > "the chip does not support it but does not report an error when reading
> > it" _is_ a valid reason. So what happens when the PMBus core reads
> > PMBUS_VOUT_MODE ? Does the chip return an error, or some random data ?
> >
>
> Still waiting for a reply.
>
> Guenter
>
Hi, Guenter

Sorry to have kept you waiting.

Best regards,
Ainux Wang.

Re: [PATCH v5] hwmon: (pmbus) Add support for MPS MP2949A

[Guenter Roeck]

On 6/28/21 6:26 PM, Ainux Wang wrote:
> On Thu, 24 Jun 2021 at 21:17, Guenter Roeck <linux@roeck-us.net> wrote:
>>
>> On Wed, Jun 23, 2021 at 08:54:26AM +0800, ainux.wang@gmail.com wrote:
>>> From: "Ainux.Wang" <ainux.wang@gmail.com>
>>>
>>> Add support for MP2949A device from Monolithic Power Systems, Inc. (MPS).
>>> This is a triple-loop, digital, multi-phase controller.
>>> This device:
>>> - Supports up to three power rail.
>>> - Provides 6 pulse-width modulations (PWMs), and can be configured up
>>>    to 6-phase operation for Rail A , up to 2-phase operation for Rail B
>>>    and up to 1-phase operation for Rail C.
>>> - The PMBus registers are distributed into three pages: Page 0, Page 1,
>>>    Page 2. Page 0 contains the registers for Rail A and most of the common
>>>    settings for all of the rails. Page 1 contains register information for
>>>    Rail B. Page 2 contains register information for Rail C.
>>> - The MP2949A supports both 5mV VID step and 10mv VID step for IMVP8 and
>>>    IMVP9.
>>>
>>> Signed-off-by: Ainux.Wang <ainux.wang@gmail.com>
>>> ---
>>> v5:
>>> - Moved change log to right here.
>>> v4:
>>> - Removed mp2949a_read_byte_data().
>>
>> Your other question left me confused. I had previously asked to provide
>> a rationale for filtering out the PMBUS_VOUT_MODE command, and I had
>> stated that "the chip does not support it" is not a valid reason. However,
>> "the chip does not support it but does not report an error when reading
>> it" _is_ a valid reason. So what happens when the PMBus core reads
>> PMBUS_VOUT_MODE ? Does the chip return an error, or some random data ?
>>
>> Thanks,
>> Guenter
>>
> Hi, Guenter
> 
> I have not been clear about the cause of this problem that
> "the chip does not support it is not a valid reason".
> 
> However, i have added some "printk", i found the chip will return some
> random data,
> when the PMbus core reads PMBUS_STATUS and PMBUS_VOUT_MODE.
> 
> So, I do not known what should i do, when the PMbus core reads PMBUS_STATUS.
> and i have knwon that use "This chip do not support the VOUT_MODE command,
> the chip does not support it but return some random data when reading
> " instead of
> "
>                 /*
>                  * This chip do not support the VOUT_MODE command.
>                  * There is not VOUT_MODE command in MP2949A datasheet P29~P31.
>                  * So this is EINVAL in here.
>                 */
> "
> Now, there is only one question left, what should the PMbus do, the
> chip return random data,
> when it reads PMBUS_STATUS by i2c_smbus_read_word_data() or
> i2c_smbus_read_byte_data()?
> Can the PMbus core use  pmbus_read_status_byte() and
> pmbus_read_status_word() instead of
> i2c_smbus_read_byte_data() and i2c_smbus_read_word_data() ?
> 

The driver should implement a read_byte_data() function and either
simulate PMBUS_VOUT_MODE and let it return whatever makes sense for
the driver, or have it return -EINVAL.

For the status register, handling is a bit more difficult. For this, we will
need an introductory patch. That patch needs to change pmbus_init_common()
to call pmbus_read_status_word() and pmbus_read_status_byte() instead
of i2c_smbus_read_word_data() and i2c_smbus_read_byte_data() (with page set
to -1).
The driver patch then needs to implement a read_word_data() function and
have it simulate the PMBUS_STATUS_WORD command. Or, alternatively,
have the read_word_data() function return -EINVAL for PMBUS_STATUS_WORD,
and simulate PMBUS_STATUS_BYTE in the read_byte_data callback.

Thanks,
Guenter

Re: [PATCH v5] hwmon: (pmbus) Add support for MPS MP2949A

[Ainux Wang]

On Tue, 29 Jun 2021 at 10:20, Guenter Roeck <linux@roeck-us.net> wrote:
>
> On 6/28/21 6:26 PM, Ainux Wang wrote:
> > On Thu, 24 Jun 2021 at 21:17, Guenter Roeck <linux@roeck-us.net> wrote:
> >>
> >> On Wed, Jun 23, 2021 at 08:54:26AM +0800, ainux.wang@gmail.com wrote:
> >>> From: "Ainux.Wang" <ainux.wang@gmail.com>
> >>>
> >>> Add support for MP2949A device from Monolithic Power Systems, Inc. (MPS).
> >>> This is a triple-loop, digital, multi-phase controller.
> >>> This device:
> >>> - Supports up to three power rail.
> >>> - Provides 6 pulse-width modulations (PWMs), and can be configured up
> >>>    to 6-phase operation for Rail A , up to 2-phase operation for Rail B
> >>>    and up to 1-phase operation for Rail C.
> >>> - The PMBus registers are distributed into three pages: Page 0, Page 1,
> >>>    Page 2. Page 0 contains the registers for Rail A and most of the common
> >>>    settings for all of the rails. Page 1 contains register information for
> >>>    Rail B. Page 2 contains register information for Rail C.
> >>> - The MP2949A supports both 5mV VID step and 10mv VID step for IMVP8 and
> >>>    IMVP9.
> >>>
> >>> Signed-off-by: Ainux.Wang <ainux.wang@gmail.com>
> >>> ---
> >>> v5:
> >>> - Moved change log to right here.
> >>> v4:
> >>> - Removed mp2949a_read_byte_data().
> >>
> >> Your other question left me confused. I had previously asked to provide
> >> a rationale for filtering out the PMBUS_VOUT_MODE command, and I had
> >> stated that "the chip does not support it" is not a valid reason. However,
> >> "the chip does not support it but does not report an error when reading
> >> it" _is_ a valid reason. So what happens when the PMBus core reads
> >> PMBUS_VOUT_MODE ? Does the chip return an error, or some random data ?
> >>
> >> Thanks,
> >> Guenter
> >>
> > Hi, Guenter
> >
> > I have not been clear about the cause of this problem that
> > "the chip does not support it is not a valid reason".
> >
> > However, i have added some "printk", i found the chip will return some
> > random data,
> > when the PMbus core reads PMBUS_STATUS and PMBUS_VOUT_MODE.
> >
> > So, I do not known what should i do, when the PMbus core reads PMBUS_STATUS.
> > and i have knwon that use "This chip do not support the VOUT_MODE command,
> > the chip does not support it but return some random data when reading
> > " instead of
> > "
> >                 /*
> >                  * This chip do not support the VOUT_MODE command.
> >                  * There is not VOUT_MODE command in MP2949A datasheet P29~P31.
> >                  * So this is EINVAL in here.
> >                 */
> > "
> > Now, there is only one question left, what should the PMbus do, the
> > chip return random data,
> > when it reads PMBUS_STATUS by i2c_smbus_read_word_data() or
> > i2c_smbus_read_byte_data()?
> > Can the PMbus core use  pmbus_read_status_byte() and
> > pmbus_read_status_word() instead of
> > i2c_smbus_read_byte_data() and i2c_smbus_read_word_data() ?
> >
>
> The driver should implement a read_byte_data() function and either
> simulate PMBUS_VOUT_MODE and let it return whatever makes sense for
> the driver, or have it return -EINVAL.
>
> For the status register, handling is a bit more difficult. For this, we will
> need an introductory patch. That patch needs to change pmbus_init_common()
> to call pmbus_read_status_word() and pmbus_read_status_byte() instead
> of i2c_smbus_read_word_data() and i2c_smbus_read_byte_data() (with page set
> to -1).
> The driver patch then needs to implement a read_word_data() function and
> have it simulate the PMBUS_STATUS_WORD command. Or, alternatively,
> have the read_word_data() function return -EINVAL for PMBUS_STATUS_WORD,
> and simulate PMBUS_STATUS_BYTE in the read_byte_data callback.
>
> Thanks,
> Guenter
Hi, Guenter

Very nice, that is what i mean, we have the same idea, I am going to
revise pmbus_init_common(),
pmbus_check_register and so on.

Best regards,
Ainux Wang.