Thread (2 messages) flat view 2 messages, 2 authors, 2021-06-17

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

From: Guenter Roeck <linux@roeck-us.net>
Date: 2021-06-17 12:34:45
Also in: linux-hwmon 

On Thu, Jun 17, 2021 at 05:43:23PM +0800, ainux.wang@gmail.com wrote:
From: "Ainux.Wang" <redacted>

Add support for MP2949A device from Monolithic Power Systems, Inc. (MPS)
vendor. 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 with only one DAC for each rail to generate REF.

Signed-off-by: Ainux.Wang <redacted>
---
 Documentation/hwmon/mp2949a.rst  | 48 ++++++++++++++++++
Reference needs to be added to Documentation/hwmon/index.rst.

 drivers/hwmon/pmbus/Kconfig      |  9 ++++
 drivers/hwmon/pmbus/Makefile     |  1 +
 drivers/hwmon/pmbus/mp2949a.c    | 83 ++++++++++++++++++++++++++++++++
 drivers/hwmon/pmbus/pmbus.h      |  6 +++
 drivers/hwmon/pmbus/pmbus_core.c | 18 +++++--
Changes to the PMBus core need to be submitted as separate patches.
quoted hunk ↗ jump to hunk
 6 files changed, 160 insertions(+), 5 deletions(-)
 create mode 100644 Documentation/hwmon/mp2949a.rst
 create mode 100644 drivers/hwmon/pmbus/mp2949a.c

diff --git a/Documentation/hwmon/mp2949a.rst b/Documentation/hwmon/mp2949a.rst
new file mode 100644
index 000000000000..82ab15e0588b
--- /dev/null
+++ b/Documentation/hwmon/mp2949a.rst
@@ -0,0 +1,48 @@
+.. 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)
+vendor triple-loop, digital, multi-phase controller MP2949A.
drop 'vendor'

+
+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 with only one DAC for each rail to generate REF.
+
+Device supports:
+
+- SVID interface.
+- PMBus interface.
+
+Device complaint with:
compliant
quoted hunk ↗ jump to hunk
+
+- PMBus rev 1.2 interface.
+
+Device supports direct format for reading output power.
+Device supports linear format for reading input voltage and 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..2b51176d8921
--- /dev/null
+++ b/drivers/hwmon/pmbus/mp2949a.c
@@ -0,0 +1,83 @@
+// 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
+
+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,
+	.skip_icp = true,
We already have a means to specify device specific flags
(pmbus_platform_data). Please use it when needed.

+};
+
+static int mp2949a_probe(struct i2c_client *client,
+			  const struct i2c_device_id *id)
+{
+	struct pmbus_driver_info *info;
+	int i;
+
+	info = devm_kmemdup(&client->dev, &mp2949a_info, sizeof(*info),
+			    GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	for (i = 0; i < MP2949A_PAGE_NUM; i++)
+		info->vrm_version[i] = vr12;
The chip supports both 5mv step size (vr12/imvp8) and 10mv step size
(imvp9). This suggests that the driver should identify the mode
dynamically using the identify callback and set vrm_version based
on MFR_VR_CONFIG bit 5.
quoted hunk ↗ jump to hunk
+
+	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 [off-list ref]");
+MODULE_DESCRIPTION("PMBus driver for Monolithic Power Systems MP2949A");
+MODULE_LICENSE("GPL");
diff --git a/drivers/hwmon/pmbus/pmbus.h b/drivers/hwmon/pmbus/pmbus.h
index 3968924f8533..fd329670876d 100644
--- a/drivers/hwmon/pmbus/pmbus.h
+++ b/drivers/hwmon/pmbus/pmbus.h
@@ -454,6 +454,12 @@ struct pmbus_driver_info {
 
 	/* custom attributes */
 	const struct attribute_group **groups;
+
+	/*
+	 * Skip identify chip parameters,
+	 * some device do not support the PMBUS_VOUT_MODE.
+	 */
+	bool skip_icp;
 };
 
 /* Regulator ops */
diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index bbd745178147..644bef5cdafd 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -2248,13 +2248,21 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
 		return -ENODEV;
 	}
 
-	for (page = 0; page < info->pages; page++) {
-		ret = pmbus_identify_common(client, data, page);
-		if (ret < 0) {
-			dev_err(dev, "Failed to identify chip capabilities\n");
-			return ret;
+	/*
+	 * Some device do not support the PMBUS_VOUT_MODE,
+	 * and the driver of device has known correct formats,
+	 * so the driver set skip_icp to true.
+	 */
The existing code should not affect device behavior. A failure to read
PMBUS_VOUT_MODE does not result in an error. As such, there is no reason
to add this flag. The only reason to add such a flag would be that the chip
returns bad data when reading PMBUS_VOUT_MODE. However, even that could
be (and is) handled by implementing a custom read_byte_data function to
catch the read and return the expected value(s). This would be a possible
alternative to using the identify callback if the chip does not return
an error when reading PMBUS_VOUT_MODE.

Guenter
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