LinuxLists.cc - [PATCH v1 2/2] hwmon: pmbus: Add ltc4286 driver

2023-04-24 10:21:21

Subject: [PATCH v1 2/2] hwmon: pmbus: Add ltc4286 driver

Add support for ltc4286 driver

Signed-off-by: Delphine CC Chiu <[email protected]>
---
drivers/hwmon/pmbus/Kconfig | 9 +++
drivers/hwmon/pmbus/Makefile | 1 +
drivers/hwmon/pmbus/ltc4286.c | 142 ++++++++++++++++++++++++++++++++++
3 files changed, 152 insertions(+)
create mode 100644 drivers/hwmon/pmbus/ltc4286.c

diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
index 59d9a7430499..1230d910d681 100644
--- a/drivers/hwmon/pmbus/Kconfig
+++ b/drivers/hwmon/pmbus/Kconfig
@@ -218,6 +218,15 @@ config SENSORS_LTC3815
This driver can also be built as a module. If so, the module will
be called ltc3815.

+config SENSORS_LTC4286
+ bool "Linear Technologies LTC4286"
+ help
+ If you say yes here you get hardware monitoring support for Linear
+ Technology LTC4286.
+
+ This driver can also be built as a module. If so, the module will
+ be called ltc4286.
+
config SENSORS_MAX15301
tristate "Maxim MAX15301"
help
diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
index 3ae019916267..540265539580 100644
--- a/drivers/hwmon/pmbus/Makefile
+++ b/drivers/hwmon/pmbus/Makefile
@@ -23,6 +23,7 @@ obj-$(CONFIG_SENSORS_LM25066) += lm25066.o
obj-$(CONFIG_SENSORS_LT7182S) += lt7182s.o
obj-$(CONFIG_SENSORS_LTC2978) += ltc2978.o
obj-$(CONFIG_SENSORS_LTC3815) += ltc3815.o
+obj-$(CONFIG_SENSORS_LTC4286) += ltc4286.o
obj-$(CONFIG_SENSORS_MAX15301) += max15301.o
obj-$(CONFIG_SENSORS_MAX16064) += max16064.o
obj-$(CONFIG_SENSORS_MAX16601) += max16601.o
diff --git a/drivers/hwmon/pmbus/ltc4286.c b/drivers/hwmon/pmbus/ltc4286.c
new file mode 100644
index 000000000000..474f4ec9107c
--- /dev/null
+++ b/drivers/hwmon/pmbus/ltc4286.c
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Hardware monitoring driver for LTC4286 Hot-Swap Controller
+ *
+ * Copyright (c) 2023 Linear Technology
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pmbus.h>
+#include "pmbus.h"
+
+// LTC4286 register
+#define LTC4286_MFR_CONFIG1 (0xF2)
+
+// LTC4286 configuration
+#define VRANGE_SELECT (1 << 1)
+
+#define LTC4286_MFR_ID_SIZE 3
+
+enum chips { ltc4286, ltc4287 };
+
+static struct pmbus_driver_info ltc4286_info = {
+ .pages = 1,
+ .format[PSC_VOLTAGE_IN] = direct,
+ .format[PSC_VOLTAGE_OUT] = direct,
+ .format[PSC_CURRENT_OUT] = direct,
+ .format[PSC_POWER] = direct,
+ .format[PSC_TEMPERATURE] = direct,
+ .m[PSC_VOLTAGE_IN] = 32,
+ .b[PSC_VOLTAGE_IN] = 0,
+ .R[PSC_VOLTAGE_IN] = 1,
+ .m[PSC_VOLTAGE_OUT] = 32,
+ .b[PSC_VOLTAGE_OUT] = 0,
+ .R[PSC_VOLTAGE_OUT] = 1,
+ .m[PSC_CURRENT_OUT] = 1024,
+ .b[PSC_CURRENT_OUT] = 0,
+ .R[PSC_CURRENT_OUT] = 3 - 6,
+ .m[PSC_POWER] = 1,
+ .b[PSC_POWER] = 0,
+ .R[PSC_POWER] = 4 - 6,
+ .m[PSC_TEMPERATURE] = 1,
+ .b[PSC_TEMPERATURE] = 273.15,
+ .R[PSC_TEMPERATURE] = 0,
+ .func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT |
+ PMBUS_HAVE_PIN | PMBUS_HAVE_TEMP,
+};
+
+static int ltc4286_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ int ret;
+ u8 block_buffer[I2C_SMBUS_BLOCK_MAX + 1];
+ struct device *dev = &client->dev;
+ struct pmbus_driver_info *info;
+ u32 rsense;
+
+ ret = i2c_smbus_read_block_data(client, PMBUS_MFR_ID, block_buffer);
+ if (ret < 0) {
+ dev_err(&client->dev, "failed to read manufacturer id\n");
+ return ret;
+ }
+
+ /* Refer to ltc4286 datasheet page 20
+ * the default manufacturer id is LTC
+ */
+ if (ret != LTC4286_MFR_ID_SIZE ||
+ strncmp(block_buffer, "LTC", LTC4286_MFR_ID_SIZE)) {
+ dev_err(&client->dev, "unsupported manufacturer id\n");
+ return -ENODEV;
+ }
+
+ ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, block_buffer);
+ if (ret < 0) {
+ dev_err(&client->dev, "failed to read manufacturer model\n");
+ return ret;
+ }
+
+ ret = of_property_read_u32(client->dev.of_node, "rsense-micro-ohms",
+ &rsense);
+ if (ret < 0)
+ return ret;
+
+ if (rsense == 0)
+ return -EINVAL;
+
+ info = &ltc4286_info;
+
+ /* Default of VRANGE_SELECT = 1 */
+ if (device_property_read_bool(dev, "vrange_select_25p6")) {
+ /* Setup MFR1 CONFIG register bit 1 VRANGE_SELECT */
+ ret = i2c_smbus_read_word_data(client, LTC4286_MFR_CONFIG1);
+ if (ret < 0) {
+ dev_err(&client->dev,
+ "failed to read manufacturer configuration one\n");
+ return ret;
+ }
+
+ ret &= ~VRANGE_SELECT; /* VRANGE_SELECT = 0, 25.6V */
+ i2c_smbus_write_word_data(client, LTC4286_MFR_CONFIG1, ret);
+
+ info->m[PSC_VOLTAGE_IN] = 128;
+ info->m[PSC_VOLTAGE_OUT] = 128;
+ info->m[PSC_POWER] = 4 * rsense;
+ } else {
+ info->m[PSC_POWER] = rsense;
+ }
+
+ info->m[PSC_CURRENT_OUT] = 1024 * rsense;
+
+ return pmbus_do_probe(client, info);
+}
+
+static const struct i2c_device_id ltc4286_id[] = { { "ltc4286", ltc4286 },
+ { "ltc4287", ltc4287 },
+ {} };
+MODULE_DEVICE_TABLE(i2c, ltc4286_id);
+
+static const struct of_device_id ltc4286_of_match[] = {
+ { .compatible = "lltc,ltc4286" },
+ { .compatible = "lltc,ltc4287" },
+ {}
+};
+
+/* This is the driver that will be inserted */
+static struct i2c_driver ltc4286_driver = {
+ .driver = {
+ .name = "ltc4286",
+ .of_match_table = ltc4286_of_match,
+ },
+ .probe = ltc4286_probe,
+ .id_table = ltc4286_id,
+};
+
+module_i2c_driver(ltc4286_driver);
+
+MODULE_AUTHOR("Delphine CC Chiu <[email protected]>");
+MODULE_DESCRIPTION("PMBUS driver for LTC4286 and compatibles");
+MODULE_LICENSE("GPL");
--
2.17.1

2023-04-24 14:15:44

by Guenter Roeck

[permalink] [raw]

Subject: Re: [PATCH v1 2/2] hwmon: pmbus: Add ltc4286 driver

On Mon, Apr 24, 2023 at 06:13:50PM +0800, Delphine CC Chiu wrote:
> Add support for ltc4286 driver

The patch does not add support for a driver, it adds support for a chip.

>
> Signed-off-by: Delphine CC Chiu <[email protected]>
> ---
> drivers/hwmon/pmbus/Kconfig | 9 +++
> drivers/hwmon/pmbus/Makefile | 1 +
> drivers/hwmon/pmbus/ltc4286.c | 142 ++++++++++++++++++++++++++++++++++

Documentation is missing.

> 3 files changed, 152 insertions(+)
> create mode 100644 drivers/hwmon/pmbus/ltc4286.c
>
> diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
> index 59d9a7430499..1230d910d681 100644
> --- a/drivers/hwmon/pmbus/Kconfig
> +++ b/drivers/hwmon/pmbus/Kconfig
> @@ -218,6 +218,15 @@ config SENSORS_LTC3815
> This driver can also be built as a module. If so, the module will
> be called ltc3815.
>
> +config SENSORS_LTC4286
> + bool "Linear Technologies LTC4286"

Analog Devices ?

> + help
> + If you say yes here you get hardware monitoring support for Linear
> + Technology LTC4286.
> +
> + This driver can also be built as a module. If so, the module will
> + be called ltc4286.
> +
> config SENSORS_MAX15301
> tristate "Maxim MAX15301"
> help
> diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
> index 3ae019916267..540265539580 100644
> --- a/drivers/hwmon/pmbus/Makefile
> +++ b/drivers/hwmon/pmbus/Makefile
> @@ -23,6 +23,7 @@ obj-$(CONFIG_SENSORS_LM25066) += lm25066.o
> obj-$(CONFIG_SENSORS_LT7182S) += lt7182s.o
> obj-$(CONFIG_SENSORS_LTC2978) += ltc2978.o
> obj-$(CONFIG_SENSORS_LTC3815) += ltc3815.o
> +obj-$(CONFIG_SENSORS_LTC4286) += ltc4286.o
> obj-$(CONFIG_SENSORS_MAX15301) += max15301.o
> obj-$(CONFIG_SENSORS_MAX16064) += max16064.o
> obj-$(CONFIG_SENSORS_MAX16601) += max16601.o
> diff --git a/drivers/hwmon/pmbus/ltc4286.c b/drivers/hwmon/pmbus/ltc4286.c
> new file mode 100644
> index 000000000000..474f4ec9107c
> --- /dev/null
> +++ b/drivers/hwmon/pmbus/ltc4286.c
> @@ -0,0 +1,142 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Hardware monitoring driver for LTC4286 Hot-Swap Controller
> + *
> + * Copyright (c) 2023 Linear Technology

Really ?

> + */
> +
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/pmbus.h>
> +#include "pmbus.h"
> +
> +// LTC4286 register

Please no C++ comments in the code.

> +#define LTC4286_MFR_CONFIG1 (0xF2)

Unnecessary ( )

> +
> +// LTC4286 configuration
> +#define VRANGE_SELECT (1 << 1)

#define<space>DEFINE<tab>value, please. Also, please use BIT() macros
where appropriate.
> +
> +#define LTC4286_MFR_ID_SIZE 3
> +
> +enum chips { ltc4286, ltc4287 };

There is no LTC4287 according to information available in public.
It has not even be announced.

Besides, the above enum is not really used anywhere and therefore
has zero value. Maybe the LTC4287 is not yet released. Even then,
there is no value listing it here because its parameters seem
to be identical to LTC4286.

> +
> +static struct pmbus_driver_info ltc4286_info = {
> + .pages = 1,
> + .format[PSC_VOLTAGE_IN] = direct,
> + .format[PSC_VOLTAGE_OUT] = direct,
> + .format[PSC_CURRENT_OUT] = direct,
> + .format[PSC_POWER] = direct,
> + .format[PSC_TEMPERATURE] = direct,
> + .m[PSC_VOLTAGE_IN] = 32,
> + .b[PSC_VOLTAGE_IN] = 0,
> + .R[PSC_VOLTAGE_IN] = 1,
> + .m[PSC_VOLTAGE_OUT] = 32,
> + .b[PSC_VOLTAGE_OUT] = 0,
> + .R[PSC_VOLTAGE_OUT] = 1,
> + .m[PSC_CURRENT_OUT] = 1024,
> + .b[PSC_CURRENT_OUT] = 0,
> + .R[PSC_CURRENT_OUT] = 3 - 6,

This needs explanation.

> + .m[PSC_POWER] = 1,
> + .b[PSC_POWER] = 0,
> + .R[PSC_POWER] = 4 - 6,

This needs explanation.

> + .m[PSC_TEMPERATURE] = 1,
> + .b[PSC_TEMPERATURE] = 273.15,

Assigning a float to an int doesn't make much sense.

> + .R[PSC_TEMPERATURE] = 0,
> + .func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT |
> + PMBUS_HAVE_PIN | PMBUS_HAVE_TEMP,

The chip does have a number of status registers.

> +};
> +
> +static int ltc4286_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + int ret;
> + u8 block_buffer[I2C_SMBUS_BLOCK_MAX + 1];
> + struct device *dev = &client->dev;
> + struct pmbus_driver_info *info;
> + u32 rsense;
> +
> + ret = i2c_smbus_read_block_data(client, PMBUS_MFR_ID, block_buffer);
> + if (ret < 0) {
> + dev_err(&client->dev, "failed to read manufacturer id\n");

Kind of pointless to declare a local 'dev' variable and not use it.

> + return ret;
> + }
> +
> + /* Refer to ltc4286 datasheet page 20
> + * the default manufacturer id is LTC

Why "default" ?

> + */

Please use standard multi-line comments.

> + if (ret != LTC4286_MFR_ID_SIZE ||
> + strncmp(block_buffer, "LTC", LTC4286_MFR_ID_SIZE)) {
> + dev_err(&client->dev, "unsupported manufacturer id\n");
> + return -ENODEV;
> + }
> +
> + ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, block_buffer);
> + if (ret < 0) {
> + dev_err(&client->dev, "failed to read manufacturer model\n");
> + return ret;
> + }

Why read the model if you don't do anything with it ?

> +
> + ret = of_property_read_u32(client->dev.of_node, "rsense-micro-ohms",
> + &rsense);
> + if (ret < 0)
> + return ret;
> +
> + if (rsense == 0)
> + return -EINVAL;
> +

There should be a default for systems not supporting devicetree.

> + info = &ltc4286_info;
> +
> + /* Default of VRANGE_SELECT = 1 */
> + if (device_property_read_bool(dev, "vrange_select_25p6")) {
> + /* Setup MFR1 CONFIG register bit 1 VRANGE_SELECT */
> + ret = i2c_smbus_read_word_data(client, LTC4286_MFR_CONFIG1);
> + if (ret < 0) {
> + dev_err(&client->dev,
> + "failed to read manufacturer configuration one\n");
> + return ret;
> + }
> +
> + ret &= ~VRANGE_SELECT; /* VRANGE_SELECT = 0, 25.6V */
> + i2c_smbus_write_word_data(client, LTC4286_MFR_CONFIG1, ret);

Error check missing.

> +
> + info->m[PSC_VOLTAGE_IN] = 128;
> + info->m[PSC_VOLTAGE_OUT] = 128;
> + info->m[PSC_POWER] = 4 * rsense;
> + } else {
> + info->m[PSC_POWER] = rsense;

This just takes the current configuration, and assumes it is the default.
That may not be correct. The chip may have been configured by the BIOS,
or manually.

> + }
> +

The code assumes that there is only a single chip in the system, or that
the configuration of all chips is identical. This is not necessarily
correct.

> + info->m[PSC_CURRENT_OUT] = 1024 * rsense;
> +
> + return pmbus_do_probe(client, info);
> +}
> +
> +static const struct i2c_device_id ltc4286_id[] = { { "ltc4286", ltc4286 },
> + { "ltc4287", ltc4287 },

Even if LTC4287 existed, assigning the ID here ...

> + {} };
> +MODULE_DEVICE_TABLE(i2c, ltc4286_id);
> +
> +static const struct of_device_id ltc4286_of_match[] = {
> + { .compatible = "lltc,ltc4286" },
> + { .compatible = "lltc,ltc4287" },

... but not here defeats having it in the first place.

> + {}
> +};

MODULE_DEVOCE_TABLE() missing.

> +
> +/* This is the driver that will be inserted */

Useless comment

> +static struct i2c_driver ltc4286_driver = {
> + .driver = {
> + .name = "ltc4286",
> + .of_match_table = ltc4286_of_match,
> + },
> + .probe = ltc4286_probe,
> + .id_table = ltc4286_id,
> +};
> +
> +module_i2c_driver(ltc4286_driver);
> +
> +MODULE_AUTHOR("Delphine CC Chiu <[email protected]>");
> +MODULE_DESCRIPTION("PMBUS driver for LTC4286 and compatibles");
> +MODULE_LICENSE("GPL");
> --
> 2.17.1
>

2023-04-25 04:52:08

by kernel test robot

[permalink] [raw]

Subject: Re: [PATCH v1 2/2] hwmon: pmbus: Add ltc4286 driver

Hi Delphine,

kernel test robot noticed the following build errors:

[auto build test ERROR on groeck-staging/hwmon-next]
[also build test ERROR on linus/master v6.3 next-20230424]
[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/Delphine-CC-Chiu/dt-bindings-hwmon-Add-lltc-ltc4286-driver-bindings/20230424-181521
base: https://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging.git hwmon-next
patch link: https://lore.kernel.org/r/20230424101352.28117-3-Delphine_CC_Chiu%40Wiwynn.com
patch subject: [PATCH v1 2/2] hwmon: pmbus: Add ltc4286 driver
config: riscv-randconfig-r021-20230425 (https://download.01.org/0day-ci/archive/20230425/[email protected]/config)
compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project 437b7602e4a998220871de78afcb020b9c14a661)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# install riscv cross compiling tool for clang build
# apt-get install binutils-riscv64-linux-gnu
# https://github.com/intel-lab-lkp/linux/commit/318b8a252bb2d7430f1cf7b93bb5df8d0e4fee29
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Delphine-CC-Chiu/dt-bindings-hwmon-Add-lltc-ltc4286-driver-bindings/20230424-181521
git checkout 318b8a252bb2d7430f1cf7b93bb5df8d0e4fee29
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=riscv olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash drivers/hwmon/pmbus/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <[email protected]>
| Link: https://lore.kernel.org/oe-kbuild-all/[email protected]/

All error/warnings (new ones prefixed by >>):

>> drivers/hwmon/pmbus/ltc4286.c:46:24: warning: implicit conversion from 'double' to 'int' changes value from 273.15 to 273 [-Wliteral-conversion]
.b[PSC_TEMPERATURE] = 273.15,
^~~~~~
>> drivers/hwmon/pmbus/ltc4286.c:134:11: error: incompatible function pointer types initializing 'int (*)(struct i2c_client *)' with an expression of type 'int (struct i2c_client *, const struct i2c_device_id *)' [-Wincompatible-function-pointer-types]
.probe = ltc4286_probe,
^~~~~~~~~~~~~
1 warning and 1 error generated.

vim +134 drivers/hwmon/pmbus/ltc4286.c

25
26 static struct pmbus_driver_info ltc4286_info = {
27 .pages = 1,
28 .format[PSC_VOLTAGE_IN] = direct,
29 .format[PSC_VOLTAGE_OUT] = direct,
30 .format[PSC_CURRENT_OUT] = direct,
31 .format[PSC_POWER] = direct,
32 .format[PSC_TEMPERATURE] = direct,
33 .m[PSC_VOLTAGE_IN] = 32,
34 .b[PSC_VOLTAGE_IN] = 0,
35 .R[PSC_VOLTAGE_IN] = 1,
36 .m[PSC_VOLTAGE_OUT] = 32,
37 .b[PSC_VOLTAGE_OUT] = 0,
38 .R[PSC_VOLTAGE_OUT] = 1,
39 .m[PSC_CURRENT_OUT] = 1024,
40 .b[PSC_CURRENT_OUT] = 0,
41 .R[PSC_CURRENT_OUT] = 3 - 6,
42 .m[PSC_POWER] = 1,
43 .b[PSC_POWER] = 0,
44 .R[PSC_POWER] = 4 - 6,
45 .m[PSC_TEMPERATURE] = 1,
> 46 .b[PSC_TEMPERATURE] = 273.15,
47 .R[PSC_TEMPERATURE] = 0,
48 .func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT |
49 PMBUS_HAVE_PIN | PMBUS_HAVE_TEMP,
50 };
51
52 static int ltc4286_probe(struct i2c_client *client,
53 const struct i2c_device_id *id)
54 {
55 int ret;
56 u8 block_buffer[I2C_SMBUS_BLOCK_MAX + 1];
57 struct device *dev = &client->dev;
58 struct pmbus_driver_info *info;
59 u32 rsense;
60
61 ret = i2c_smbus_read_block_data(client, PMBUS_MFR_ID, block_buffer);
62 if (ret < 0) {
63 dev_err(&client->dev, "failed to read manufacturer id\n");
64 return ret;
65 }
66
67 /* Refer to ltc4286 datasheet page 20
68 * the default manufacturer id is LTC
69 */
70 if (ret != LTC4286_MFR_ID_SIZE ||
71 strncmp(block_buffer, "LTC", LTC4286_MFR_ID_SIZE)) {
72 dev_err(&client->dev, "unsupported manufacturer id\n");
73 return -ENODEV;
74 }
75
76 ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, block_buffer);
77 if (ret < 0) {
78 dev_err(&client->dev, "failed to read manufacturer model\n");
79 return ret;
80 }
81
82 ret = of_property_read_u32(client->dev.of_node, "rsense-micro-ohms",
83 &rsense);
84 if (ret < 0)
85 return ret;
86
87 if (rsense == 0)
88 return -EINVAL;
89
90 info = &ltc4286_info;
91
92 /* Default of VRANGE_SELECT = 1 */
93 if (device_property_read_bool(dev, "vrange_select_25p6")) {
94 /* Setup MFR1 CONFIG register bit 1 VRANGE_SELECT */
95 ret = i2c_smbus_read_word_data(client, LTC4286_MFR_CONFIG1);
96 if (ret < 0) {
97 dev_err(&client->dev,
98 "failed to read manufacturer configuration one\n");
99 return ret;
100 }
101
102 ret &= ~VRANGE_SELECT; /* VRANGE_SELECT = 0, 25.6V */
103 i2c_smbus_write_word_data(client, LTC4286_MFR_CONFIG1, ret);
104
105 info->m[PSC_VOLTAGE_IN] = 128;
106 info->m[PSC_VOLTAGE_OUT] = 128;
107 info->m[PSC_POWER] = 4 * rsense;
108 } else {
109 info->m[PSC_POWER] = rsense;
110 }
111
112 info->m[PSC_CURRENT_OUT] = 1024 * rsense;
113
114 return pmbus_do_probe(client, info);
115 }
116
117 static const struct i2c_device_id ltc4286_id[] = { { "ltc4286", ltc4286 },
118 { "ltc4287", ltc4287 },
119 {} };
120 MODULE_DEVICE_TABLE(i2c, ltc4286_id);
121
122 static const struct of_device_id ltc4286_of_match[] = {
123 { .compatible = "lltc,ltc4286" },
124 { .compatible = "lltc,ltc4287" },
125 {}
126 };
127
128 /* This is the driver that will be inserted */
129 static struct i2c_driver ltc4286_driver = {
130 .driver = {
131 .name = "ltc4286",
132 .of_match_table = ltc4286_of_match,
133 },
> 134 .probe = ltc4286_probe,
135 .id_table = ltc4286_id,
136 };
137

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

2023-04-25 14:08:36

by Andi Shyti

[permalink] [raw]

Subject: Re: [PATCH v1 2/2] hwmon: pmbus: Add ltc4286 driver

Hi Delphine,

On top of Guenter's comments,

[...]

> +config SENSORS_LTC4286
> + bool "Linear Technologies LTC4286"
> + help
> + If you say yes here you get hardware monitoring support for Linear
> + Technology LTC4286.

could you add a couple of words more here?

[...]

> +static int ltc4286_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + int ret;
> + u8 block_buffer[I2C_SMBUS_BLOCK_MAX + 1];
> + struct device *dev = &client->dev;
> + struct pmbus_driver_info *info;
> + u32 rsense;
> +
> + ret = i2c_smbus_read_block_data(client, PMBUS_MFR_ID, block_buffer);
> + if (ret < 0) {
> + dev_err(&client->dev, "failed to read manufacturer id\n");

you can use dev_err_probe() here:

return dev_err_probe(&client->dev, err, "failed to read manufacturer id\n");

> + return ret;
> + }
> +
> + /* Refer to ltc4286 datasheet page 20
> + * the default manufacturer id is LTC
> + */
> + if (ret != LTC4286_MFR_ID_SIZE ||
> + strncmp(block_buffer, "LTC", LTC4286_MFR_ID_SIZE)) {
> + dev_err(&client->dev, "unsupported manufacturer id\n");
> + return -ENODEV;
> + }
> +
> + ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, block_buffer);
> + if (ret < 0) {
> + dev_err(&client->dev, "failed to read manufacturer model\n");
> + return ret;
> + }

Is this read really needed?

Andi

[...]

2023-04-25 14:11:51

by Guenter Roeck

[permalink] [raw]

Subject: Re: [PATCH v1 2/2] hwmon: pmbus: Add ltc4286 driver

On 4/25/23 06:45, Andi Shyti wrote:
> Hi Delphine,
>
> On top of Guenter's comments,
>
> [...]
>
>> +config SENSORS_LTC4286
>> + bool "Linear Technologies LTC4286"
>> + help
>> + If you say yes here you get hardware monitoring support for Linear
>> + Technology LTC4286.
>
> could you add a couple of words more here?
>
> [...]
>
>> +static int ltc4286_probe(struct i2c_client *client,
>> + const struct i2c_device_id *id)
>> +{
>> + int ret;
>> + u8 block_buffer[I2C_SMBUS_BLOCK_MAX + 1];
>> + struct device *dev = &client->dev;
>> + struct pmbus_driver_info *info;
>> + u32 rsense;
>> +
>> + ret = i2c_smbus_read_block_data(client, PMBUS_MFR_ID, block_buffer);
>> + if (ret < 0) {
>> + dev_err(&client->dev, "failed to read manufacturer id\n");
>
> you can use dev_err_probe() here:
>
> return dev_err_probe(&client->dev, err, "failed to read manufacturer id\n");
>
>> + return ret;
>> + }
>> +
>> + /* Refer to ltc4286 datasheet page 20
>> + * the default manufacturer id is LTC
>> + */
>> + if (ret != LTC4286_MFR_ID_SIZE ||
>> + strncmp(block_buffer, "LTC", LTC4286_MFR_ID_SIZE)) {
>> + dev_err(&client->dev, "unsupported manufacturer id\n");
>> + return -ENODEV;
>> + }
>> +
>> + ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, block_buffer);
>> + if (ret < 0) {
>> + dev_err(&client->dev, "failed to read manufacturer model\n");
>> + return ret;
>> + }
>
> Is this read really needed?
>

It only makes sense if the returned string is actually validated.
Otherwise no.

Guenter

2023-04-30 17:59:58

by kernel test robot

[permalink] [raw]

Subject: Re: [PATCH v1 2/2] hwmon: pmbus: Add ltc4286 driver

2023-05-05 23:46:54

by kernel test robot

[permalink] [raw]

Subject: Re: [PATCH v1 2/2] hwmon: pmbus: Add ltc4286 driver

2023-07-24 02:47:12

by Delphine_CC_Chiu/WYHQ/Wiwynn

[permalink] [raw]

Subject: RE: [PATCH v1 2/2] hwmon: pmbus: Add ltc4286 driver

> -----Original Message-----
> From: Guenter Roeck <[email protected]> On Behalf Of Guenter Roeck
> Sent: Tuesday, April 25, 2023 10:09 PM
> To: Andi Shyti <[email protected]>; Delphine_CC_Chiu/WYHQ/Wiwynn
> <[email protected]>
> Cc: [email protected]; Jean Delvare <[email protected]>; Rob Herring
> <[email protected]>; Krzysztof Kozlowski
> <[email protected]>; [email protected];
> [email protected]; [email protected];
> [email protected]
> Subject: Re: [PATCH v1 2/2] hwmon: pmbus: Add ltc4286 driver
>
> Security Reminder: Please be aware that this email is sent by an external
> sender.
>
> On 4/25/23 06:45, Andi Shyti wrote:
> > Hi Delphine,
> >
> > On top of Guenter's comments,
> >
> > [...]
> >
> >> +config SENSORS_LTC4286
> >> + bool "Linear Technologies LTC4286"
> >> + help
> >> + If you say yes here you get hardware monitoring support for Linear
> >> + Technology LTC4286.
> >
> > could you add a couple of words more here?
> >
> > [...]
> >
> >> +static int ltc4286_probe(struct i2c_client *client,
> >> + const struct i2c_device_id *id) {
> >> + int ret;
> >> + u8 block_buffer[I2C_SMBUS_BLOCK_MAX + 1];
> >> + struct device *dev = &client->dev;
> >> + struct pmbus_driver_info *info;
> >> + u32 rsense;
> >> +
> >> + ret = i2c_smbus_read_block_data(client, PMBUS_MFR_ID,
> block_buffer);
> >> + if (ret < 0) {
> >> + dev_err(&client->dev, "failed to read manufacturer
> >> + id\n");
> >
> > you can use dev_err_probe() here:
> >
> > return dev_err_probe(&client->dev, err, "failed to read
> > manufacturer id\n");
> >
> >> + return ret;
> >> + }
> >> +
> >> + /* Refer to ltc4286 datasheet page 20
> >> + * the default manufacturer id is LTC
> >> + */
> >> + if (ret != LTC4286_MFR_ID_SIZE ||
> >> + strncmp(block_buffer, "LTC", LTC4286_MFR_ID_SIZE)) {
> >> + dev_err(&client->dev, "unsupported manufacturer id\n");
> >> + return -ENODEV;
> >> + }
> >> +
> >> + ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL,
> block_buffer);
> >> + if (ret < 0) {
> >> + dev_err(&client->dev, "failed to read manufacturer
> model\n");
> >> + return ret;
> >> + }
> >
> > Is this read really needed?
> >
>
> It only makes sense if the returned string is actually validated.
> Otherwise no.
>
> Guenter
We will add comaprision here.
for (mid = ltc4286_id; mid->name[0]; mid++) {
if (!strncasecmp(mid->name, block_buffer, strlen(mid->name)))
break;
}

2023-07-24 02:51:24

by Delphine_CC_Chiu/WYHQ/Wiwynn

[permalink] [raw]

Subject: RE: [PATCH v1 2/2] hwmon: pmbus: Add ltc4286 driver

> -----Original Message-----
> From: Andi Shyti <[email protected]>
> Sent: Tuesday, April 25, 2023 9:46 PM
> To: Delphine_CC_Chiu/WYHQ/Wiwynn <[email protected]>
> Cc: [email protected]; Guenter Roeck <[email protected]>; Jean Delvare
> <[email protected]>; Rob Herring <[email protected]>; Krzysztof Kozlowski
> <[email protected]>; [email protected];
> [email protected]; [email protected];
> [email protected]
> Subject: Re: [PATCH v1 2/2] hwmon: pmbus: Add ltc4286 driver
>
> Security Reminder: Please be aware that this email is sent by an external
> sender.
>
> Hi Delphine,
>
> On top of Guenter's comments,
>
> [...]
>
> > +config SENSORS_LTC4286
> > + bool "Linear Technologies LTC4286"
> > + help
> > + If you say yes here you get hardware monitoring support for Linear
> > + Technology LTC4286.
>
> could you add a couple of words more here?
We will revise as below
config SENSORS_LTC4286
bool "Analog Devices LTC4286"
help
LTC4286 is an integrated solution for hot swap applications that allows
a board to be safely inserted and removed from a live backplane.
This chip could be used to monitor voltage, current, ...etc.
If you say yes here you get hardware monitoring support for Analog
Devices LTC4286.

>
> [...]
>
> > +static int ltc4286_probe(struct i2c_client *client,
> > + const struct i2c_device_id *id) {
> > + int ret;
> > + u8 block_buffer[I2C_SMBUS_BLOCK_MAX + 1];
> > + struct device *dev = &client->dev;
> > + struct pmbus_driver_info *info;
> > + u32 rsense;
> > +
> > + ret = i2c_smbus_read_block_data(client, PMBUS_MFR_ID,
> block_buffer);
> > + if (ret < 0) {
> > + dev_err(&client->dev, "failed to read manufacturer
> > + id\n");
>
> you can use dev_err_probe() here:
We will revise as below
dev_err_probe(&client->dev, err, "failed to read manufacturer id\n");

>
> return dev_err_probe(&client->dev, err, "failed to read manufacturer
> id\n");
>
> > + return ret;
> > + }
> > +
> > + /* Refer to ltc4286 datasheet page 20
> > + * the default manufacturer id is LTC
> > + */
> > + if (ret != LTC4286_MFR_ID_SIZE ||
> > + strncmp(block_buffer, "LTC", LTC4286_MFR_ID_SIZE)) {
> > + dev_err(&client->dev, "unsupported manufacturer id\n");
> > + return -ENODEV;
> > + }
> > +
> > + ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL,
> block_buffer);
> > + if (ret < 0) {
> > + dev_err(&client->dev, "failed to read manufacturer
> model\n");
> > + return ret;
> > + }
>
> Is this read really needed?
We use this to check manufacturer model.
And we will add comparison here.
for (mid = ltc4286_id; mid->name[0]; mid++) {
if (!strncasecmp(mid->name, block_buffer, strlen(mid->name)))
break;
}

>
> Andi
>
> [...]

2023-07-24 06:20:37

by Delphine_CC_Chiu/WYHQ/Wiwynn

[permalink] [raw]

Subject: RE: [PATCH v1 2/2] hwmon: pmbus: Add ltc4286 driver

> -----Original Message-----
> From: Guenter Roeck <[email protected]> On Behalf Of Guenter Roeck
> Sent: Monday, April 24, 2023 10:14 PM
> To: Delphine_CC_Chiu/WYHQ/Wiwynn <[email protected]>
> Cc: [email protected]; Jean Delvare <[email protected]>; Rob Herring
> <[email protected]>; Krzysztof Kozlowski
> <[email protected]>; [email protected];
> [email protected]; [email protected];
> [email protected]
> Subject: Re: [PATCH v1 2/2] hwmon: pmbus: Add ltc4286 driver
>
> Security Reminder: Please be aware that this email is sent by an external
> sender.
>
> On Mon, Apr 24, 2023 at 06:13:50PM +0800, Delphine CC Chiu wrote:
> > Add support for ltc4286 driver
>
> The patch does not add support for a driver, it adds support for a chip.
Add a driver to support ltc4286 chip

>
> >
> > Signed-off-by: Delphine CC Chiu <[email protected]>
> > ---
> > drivers/hwmon/pmbus/Kconfig | 9 +++
> > drivers/hwmon/pmbus/Makefile | 1 +
> > drivers/hwmon/pmbus/ltc4286.c | 142
> > ++++++++++++++++++++++++++++++++++
>
> Documentation is missing.
Documentation is in patch one ([PATCH v1 1/2] dt-bindings: hwmon: Add lltc ltc4286 driver bindings)

>
> > 3 files changed, 152 insertions(+)
> > create mode 100644 drivers/hwmon/pmbus/ltc4286.c
> >
> > diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
> > index 59d9a7430499..1230d910d681 100644
> > --- a/drivers/hwmon/pmbus/Kconfig
> > +++ b/drivers/hwmon/pmbus/Kconfig
> > @@ -218,6 +218,15 @@ config SENSORS_LTC3815
> > This driver can also be built as a module. If so, the module will
> > be called ltc3815.
> >
> > +config SENSORS_LTC4286
> > + bool "Linear Technologies LTC4286"
>
> Analog Devices ?
We will revise to "Analog Devices LTC4286"

>
> > + help
> > + If you say yes here you get hardware monitoring support for Linear
> > + Technology LTC4286.
> > +
> > + This driver can also be built as a module. If so, the module will
> > + be called ltc4286.
> > +
> > config SENSORS_MAX15301
> > tristate "Maxim MAX15301"
> > help
> > diff --git a/drivers/hwmon/pmbus/Makefile
> > b/drivers/hwmon/pmbus/Makefile index 3ae019916267..540265539580
> 100644
> > --- a/drivers/hwmon/pmbus/Makefile
> > +++ b/drivers/hwmon/pmbus/Makefile
> > @@ -23,6 +23,7 @@ obj-$(CONFIG_SENSORS_LM25066) +=
> lm25066.o
> > obj-$(CONFIG_SENSORS_LT7182S) += lt7182s.o
> > obj-$(CONFIG_SENSORS_LTC2978) += ltc2978.o
> > obj-$(CONFIG_SENSORS_LTC3815) += ltc3815.o
> > +obj-$(CONFIG_SENSORS_LTC4286) += ltc4286.o
> > obj-$(CONFIG_SENSORS_MAX15301) += max15301.o
> > obj-$(CONFIG_SENSORS_MAX16064) += max16064.o
> > obj-$(CONFIG_SENSORS_MAX16601) += max16601.o
> > diff --git a/drivers/hwmon/pmbus/ltc4286.c
> > b/drivers/hwmon/pmbus/ltc4286.c new file mode 100644 index
> > 000000000000..474f4ec9107c
> > --- /dev/null
> > +++ b/drivers/hwmon/pmbus/ltc4286.c
> > @@ -0,0 +1,142 @@
> > +// SPDX-License-Identifier: GPL-2.0-or-later
> > +/*
> > + * Hardware monitoring driver for LTC4286 Hot-Swap Controller
> > + *
> > + * Copyright (c) 2023 Linear Technology
>
> Really ?
We will remove the copyright declaration as it was false reference from other drivers
Chip vendor doesn't support this driver, so we implement it for our own use and contribute it as Wiwynn is a system manufacturer, our server products use this chip.

>
> > + */
> > +
> > +#include <linux/err.h>
> > +#include <linux/i2c.h>
> > +#include <linux/init.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/pmbus.h>
> > +#include "pmbus.h"
> > +
> > +// LTC4286 register
>
> Please no C++ comments in the code.
We will revise to /* LTC4286 register */

>
> > +#define LTC4286_MFR_CONFIG1 (0xF2)
>
> Unnecessary ( )
We will revise to #define LTC4286_MFR_CONFIG1 0xF2

>
> > +
> > +// LTC4286 configuration
> > +#define VRANGE_SELECT (1 << 1)
>
> #define<space>DEFINE<tab>value, please. Also, please use BIT() macros where
> appropriate.
We will revise to below.
#define VRANGE_SELECT_BIT BIT(1)

> > +
> > +#define LTC4286_MFR_ID_SIZE 3
> > +
> > +enum chips { ltc4286, ltc4287 };
>
> There is no LTC4287 according to information available in public.
> It has not even be announced.
>
> Besides, the above enum is not really used anywhere and therefore has zero
> value. Maybe the LTC4287 is not yet released. Even then, there is no value
> listing it here because its parameters seem to be identical to LTC4286.
It has been announced on Analog Devices website.
Please refer to this link: https://www.analog.com/en/products/ltc2487.html#product-overview
enum chips { ltc4286 = 0, ltc4287 };
Use in v1 line 118 to list chip index instead of hardcoding

>
> > +
> > +static struct pmbus_driver_info ltc4286_info = {
> > + .pages = 1,
> > + .format[PSC_VOLTAGE_IN] = direct,
> > + .format[PSC_VOLTAGE_OUT] = direct,
> > + .format[PSC_CURRENT_OUT] = direct,
> > + .format[PSC_POWER] = direct,
> > + .format[PSC_TEMPERATURE] = direct,
> > + .m[PSC_VOLTAGE_IN] = 32,
> > + .b[PSC_VOLTAGE_IN] = 0,
> > + .R[PSC_VOLTAGE_IN] = 1,
> > + .m[PSC_VOLTAGE_OUT] = 32,
> > + .b[PSC_VOLTAGE_OUT] = 0,
> > + .R[PSC_VOLTAGE_OUT] = 1,
> > + .m[PSC_CURRENT_OUT] = 1024,
> > + .b[PSC_CURRENT_OUT] = 0,
> > + .R[PSC_CURRENT_OUT] = 3 - 6,
>
> This needs explanation.
We will add comments as below
/* Initialize the MBR as default settings which is referred to LTC4286 datasheet(March 22, 2022 version) table 3 page 16 */

>
> > + .m[PSC_POWER] = 1,
> > + .b[PSC_POWER] = 0,
> > + .R[PSC_POWER] = 4 - 6,
>
> This needs explanation.
We will add comments as below
/* To support small shunt resistor value */

>
> > + .m[PSC_TEMPERATURE] = 1,
> > + .b[PSC_TEMPERATURE] = 273.15,
>
> Assigning a float to an int doesn't make much sense.
We will revise to .b[PSC_TEMPERATURE] = 273,
However the value for this MBR is 273.15 in datasheet
We use 273 due to pmbus code limitation

>
> > + .R[PSC_TEMPERATURE] = 0,
> > + .func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT |
> PMBUS_HAVE_IOUT |
> > + PMBUS_HAVE_PIN | PMBUS_HAVE_TEMP,
>
> The chip does have a number of status registers.
We will add status registers here

>
> > +};
> > +
> > +static int ltc4286_probe(struct i2c_client *client,
> > + const struct i2c_device_id *id) {
> > + int ret;
> > + u8 block_buffer[I2C_SMBUS_BLOCK_MAX + 1];
> > + struct device *dev = &client->dev;
> > + struct pmbus_driver_info *info;
> > + u32 rsense;
> > +
> > + ret = i2c_smbus_read_block_data(client, PMBUS_MFR_ID,
> block_buffer);
> > + if (ret < 0) {
> > + dev_err(&client->dev, "failed to read manufacturer
> > + id\n");
>
> Kind of pointless to declare a local 'dev' variable and not use it.
We will drop it

>
> > + return ret;
> > + }
> > +
> > + /* Refer to ltc4286 datasheet page 20
> > + * the default manufacturer id is LTC
>
> Why "default" ?
We will revise to
/*
* Refer to ltc4286 datasheet page 20
* the manufacturer id is LTC
*/

>
> > + */
>
> Please use standard multi-line comments.
We will revise to
/*
* Refer to ltc4286 datasheet page 20
* the manufacturer id is LTC
*/

>
> > + if (ret != LTC4286_MFR_ID_SIZE ||
> > + strncmp(block_buffer, "LTC", LTC4286_MFR_ID_SIZE)) {
> > + dev_err(&client->dev, "unsupported manufacturer id\n");
> > + return -ENODEV;
> > + }
> > +
> > + ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL,
> block_buffer);
> > + if (ret < 0) {
> > + dev_err(&client->dev, "failed to read manufacturer
> model\n");
> > + return ret;
> > + }
>
> Why read the model if you don't do anything with it ?
We will add comaprision here.
for (mid = ltc4286_id; mid->name[0]; mid++) {
if (!strncasecmp(mid->name, block_buffer, strlen(mid->name)))
break;
}

>
> > +
> > + ret = of_property_read_u32(client->dev.of_node,
> "rsense-micro-ohms",
> > + &rsense);
> > + if (ret < 0)
> > + return ret;
> > +
> > + if (rsense == 0)
> > + return -EINVAL;
> > +
>
> There should be a default for systems not supporting devicetree.
After confirming with vendor, they said there is no default rsesne for this chip
The value for rsense depends on hardware engineer in each manufacturer

>
> > + info = &ltc4286_info;
> > +
> > + /* Default of VRANGE_SELECT = 1 */
> > + if (device_property_read_bool(dev, "vrange_select_25p6")) {
> > + /* Setup MFR1 CONFIG register bit 1 VRANGE_SELECT */
> > + ret = i2c_smbus_read_word_data(client,
> LTC4286_MFR_CONFIG1);
> > + if (ret < 0) {
> > + dev_err(&client->dev,
> > + "failed to read manufacturer
> configuration one\n");
> > + return ret;
> > + }
> > +
> > + ret &= ~VRANGE_SELECT; /* VRANGE_SELECT = 0, 25.6V */
> > + i2c_smbus_write_word_data(client,
> LTC4286_MFR_CONFIG1,
> > + ret);
>
> Error check missing.
ret = i2c_smbus_write_word_data(client, LTC4286_MFR_CONFIG1, ret);
if (ret < 0) {
dev_err(&client->dev, "failed to set vrange\n");
return ret;
}

>
> > +
> > + info->m[PSC_VOLTAGE_IN] = 128;
> > + info->m[PSC_VOLTAGE_OUT] = 128;
> > + info->m[PSC_POWER] = 4 * rsense;
> > + } else {
> > + info->m[PSC_POWER] = rsense;
>
> This just takes the current configuration, and assumes it is the default.
> That may not be correct. The chip may have been configured by the BIOS, or
> manually.
The MBR values are based on hardware design, so it must be set in initial stage

>
> > + }
> > +
>
> The code assumes that there is only a single chip in the system, or that the
> configuration of all chips is identical. This is not necessarily correct.
If there are more than one LTC4286 or LTC4287 chips, user can add the configuration for different chips in dts file

>
> > + info->m[PSC_CURRENT_OUT] = 1024 * rsense;
> > +
> > + return pmbus_do_probe(client, info); }
> > +
> > +static const struct i2c_device_id ltc4286_id[] = { { "ltc4286", ltc4286 },
> > + { "ltc4287",
> ltc4287
> > +},
>
> Even if LTC4287 existed, assigning the ID here ...
So do you recommend us to put this enum (enum chips { ltc4286, ltc4287 };) here?

>
> > + {} };
> > +MODULE_DEVICE_TABLE(i2c, ltc4286_id);
> > +
> > +static const struct of_device_id ltc4286_of_match[] = {
> > + { .compatible = "lltc,ltc4286" },
> > + { .compatible = "lltc,ltc4287" },
>
> ... but not here defeats having it in the first place.
So do you recommend us to not put this enum (enum chips { ltc4286, ltc4287 };) here?

>
> > + {}
> > +};
>
> MODULE_DEVOCE_TABLE() missing.
In v1 line 120

>
> > +
> > +/* This is the driver that will be inserted */
>
> Useless comment
We will drop it.

>
> > +static struct i2c_driver ltc4286_driver = {
> > + .driver = {
> > + .name = "ltc4286",
> > + .of_match_table = ltc4286_of_match,
> > + },
> > + .probe = ltc4286_probe,
> > + .id_table = ltc4286_id,
> > +};
> > +
> > +module_i2c_driver(ltc4286_driver);
> > +
> > +MODULE_AUTHOR("Delphine CC Chiu
> <[email protected]>");
> > +MODULE_DESCRIPTION("PMBUS driver for LTC4286 and compatibles");
> > +MODULE_LICENSE("GPL");
> > --
> > 2.17.1
> >

2023-07-24 07:36:07

by Guenter Roeck

[permalink] [raw]

Subject: Re: [PATCH v1 2/2] hwmon: pmbus: Add ltc4286 driver

On 7/23/23 23:03, Delphine_CC_Chiu/WYHQ/Wiwynn wrote:
>> -----Original Message-----
>> From: Guenter Roeck <[email protected]> On Behalf Of Guenter Roeck
>> Sent: Monday, April 24, 2023 10:14 PM
>> To: Delphine_CC_Chiu/WYHQ/Wiwynn <[email protected]>
>> Cc: [email protected]; Jean Delvare <[email protected]>; Rob Herring
>> <[email protected]>; Krzysztof Kozlowski
>> <[email protected]>; [email protected];
>> [email protected]; [email protected];
>> [email protected]
>> Subject: Re: [PATCH v1 2/2] hwmon: pmbus: Add ltc4286 driver
>>
>> Security Reminder: Please be aware that this email is sent by an external
>> sender.
>>
>> On Mon, Apr 24, 2023 at 06:13:50PM +0800, Delphine CC Chiu wrote:
>>> Add support for ltc4286 driver
>>
>> The patch does not add support for a driver, it adds support for a chip.
> Add a driver to support ltc4286 chip
>
>>
>>>
>>> Signed-off-by: Delphine CC Chiu <[email protected]>
>>> ---
>>> drivers/hwmon/pmbus/Kconfig | 9 +++
>>> drivers/hwmon/pmbus/Makefile | 1 +
>>> drivers/hwmon/pmbus/ltc4286.c | 142
>>> ++++++++++++++++++++++++++++++++++
>>
>> Documentation is missing.
> Documentation is in patch one ([PATCH v1 1/2] dt-bindings: hwmon: Add lltc ltc4286 driver bindings)
>

Documentation/hwmon/ltc4286.rst is expected in this patch and not as
part of the bindings. The bindings do not document the driver,
they document the chip bindings.

>>
>>> 3 files changed, 152 insertions(+)
>>> create mode 100644 drivers/hwmon/pmbus/ltc4286.c
>>>
>>> diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
>>> index 59d9a7430499..1230d910d681 100644
>>> --- a/drivers/hwmon/pmbus/Kconfig
>>> +++ b/drivers/hwmon/pmbus/Kconfig
>>> @@ -218,6 +218,15 @@ config SENSORS_LTC3815
>>> This driver can also be built as a module. If so, the module will
>>> be called ltc3815.
>>>
>>> +config SENSORS_LTC4286
>>> + bool "Linear Technologies LTC4286"
>>
>> Analog Devices ?
> We will revise to "Analog Devices LTC4286"
>
>>
>>> + help
>>> + If you say yes here you get hardware monitoring support for Linear
>>> + Technology LTC4286.
>>> +
>>> + This driver can also be built as a module. If so, the module will
>>> + be called ltc4286.
>>> +
>>> config SENSORS_MAX15301
>>> tristate "Maxim MAX15301"
>>> help
>>> diff --git a/drivers/hwmon/pmbus/Makefile
>>> b/drivers/hwmon/pmbus/Makefile index 3ae019916267..540265539580
>> 100644
>>> --- a/drivers/hwmon/pmbus/Makefile
>>> +++ b/drivers/hwmon/pmbus/Makefile
>>> @@ -23,6 +23,7 @@ obj-$(CONFIG_SENSORS_LM25066) +=
>> lm25066.o
>>> obj-$(CONFIG_SENSORS_LT7182S) += lt7182s.o
>>> obj-$(CONFIG_SENSORS_LTC2978) += ltc2978.o
>>> obj-$(CONFIG_SENSORS_LTC3815) += ltc3815.o
>>> +obj-$(CONFIG_SENSORS_LTC4286) += ltc4286.o
>>> obj-$(CONFIG_SENSORS_MAX15301) += max15301.o
>>> obj-$(CONFIG_SENSORS_MAX16064) += max16064.o
>>> obj-$(CONFIG_SENSORS_MAX16601) += max16601.o
>>> diff --git a/drivers/hwmon/pmbus/ltc4286.c
>>> b/drivers/hwmon/pmbus/ltc4286.c new file mode 100644 index
>>> 000000000000..474f4ec9107c
>>> --- /dev/null
>>> +++ b/drivers/hwmon/pmbus/ltc4286.c
>>> @@ -0,0 +1,142 @@
>>> +// SPDX-License-Identifier: GPL-2.0-or-later
>>> +/*
>>> + * Hardware monitoring driver for LTC4286 Hot-Swap Controller
>>> + *
>>> + * Copyright (c) 2023 Linear Technology
>>
>> Really ?
> We will remove the copyright declaration as it was false reference from other drivers
> Chip vendor doesn't support this driver, so we implement it for our own use and contribute it as Wiwynn is a system manufacturer, our server products use this chip.
>
>>
>>> + */
>>> +
>>> +#include <linux/err.h>
>>> +#include <linux/i2c.h>
>>> +#include <linux/init.h>
>>> +#include <linux/kernel.h>
>>> +#include <linux/module.h>
>>> +#include <linux/pmbus.h>
>>> +#include "pmbus.h"
>>> +
>>> +// LTC4286 register
>>
>> Please no C++ comments in the code.
> We will revise to /* LTC4286 register */
>
>>
>>> +#define LTC4286_MFR_CONFIG1 (0xF2)
>>
>> Unnecessary ( )
> We will revise to #define LTC4286_MFR_CONFIG1 0xF2
>
>>
>>> +
>>> +// LTC4286 configuration
>>> +#define VRANGE_SELECT (1 << 1)
>>
>> #define<space>DEFINE<tab>value, please. Also, please use BIT() macros where
>> appropriate.
> We will revise to below.
> #define VRANGE_SELECT_BIT BIT(1)
>
>>> +
>>> +#define LTC4286_MFR_ID_SIZE 3
>>> +
>>> +enum chips { ltc4286, ltc4287 };
>>
>> There is no LTC4287 according to information available in public.
>> It has not even be announced.
>>
>> Besides, the above enum is not really used anywhere and therefore has zero
>> value. Maybe the LTC4287 is not yet released. Even then, there is no value
>> listing it here because its parameters seem to be identical to LTC4286.
> It has been announced on Analog Devices website.

No, it has not.

> Please refer to this link: https://www.analog.com/en/products/ltc2487.html#product-overview
> enum chips { ltc4286 = 0, ltc4287 };
> Use in v1 line 118 to list chip index instead of hardcoding
>

ltc2487 is _not_ ltc4287.
^^ ^^

Sure, a Google search for LTC4287 returns a link to LTC2487 (!) as first response,
but LTC2487 is an ADC and has nothing but the manufacturer in common with LTC4286.

LTC4286 High Power Positive Hot-Swap Controller with Power Monitor via PMBus
LTC2487 16-Bit 2-/4-Channel ∆Σ ADC with PGA, Easy Drive and I2C Interface

I _really_ do not understand what you are trying to do here or why.

>>
>>> +
>>> +static struct pmbus_driver_info ltc4286_info = {
>>> + .pages = 1,
>>> + .format[PSC_VOLTAGE_IN] = direct,
>>> + .format[PSC_VOLTAGE_OUT] = direct,
>>> + .format[PSC_CURRENT_OUT] = direct,
>>> + .format[PSC_POWER] = direct,
>>> + .format[PSC_TEMPERATURE] = direct,
>>> + .m[PSC_VOLTAGE_IN] = 32,
>>> + .b[PSC_VOLTAGE_IN] = 0,
>>> + .R[PSC_VOLTAGE_IN] = 1,
>>> + .m[PSC_VOLTAGE_OUT] = 32,
>>> + .b[PSC_VOLTAGE_OUT] = 0,
>>> + .R[PSC_VOLTAGE_OUT] = 1,
>>> + .m[PSC_CURRENT_OUT] = 1024,
>>> + .b[PSC_CURRENT_OUT] = 0,
>>> + .R[PSC_CURRENT_OUT] = 3 - 6,
>>
>> This needs explanation.
> We will add comments as below
> /* Initialize the MBR as default settings which is referred to LTC4286 datasheet(March 22, 2022 version) table 3 page 16 */
>

That does not explain "3 - 6".

>>
>>> + .m[PSC_POWER] = 1,
>>> + .b[PSC_POWER] = 0,
>>> + .R[PSC_POWER] = 4 - 6,
>>
>> This needs explanation.
> We will add comments as below
> /* To support small shunt resistor value */
>

That does not explain "4 - 6".

>>
>>> + .m[PSC_TEMPERATURE] = 1,
>>> + .b[PSC_TEMPERATURE] = 273.15,
>>
>> Assigning a float to an int doesn't make much sense.
> We will revise to .b[PSC_TEMPERATURE] = 273,
> However the value for this MBR is 273.15 in datasheet
> We use 273 due to pmbus code limitation
>
>>
>>> + .R[PSC_TEMPERATURE] = 0,
>>> + .func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT |
>> PMBUS_HAVE_IOUT |
>>> + PMBUS_HAVE_PIN | PMBUS_HAVE_TEMP,
>>
>> The chip does have a number of status registers.
> We will add status registers here
>
>>
>>> +};
>>> +
>>> +static int ltc4286_probe(struct i2c_client *client,
>>> + const struct i2c_device_id *id) {
>>> + int ret;
>>> + u8 block_buffer[I2C_SMBUS_BLOCK_MAX + 1];
>>> + struct device *dev = &client->dev;
>>> + struct pmbus_driver_info *info;
>>> + u32 rsense;
>>> +
>>> + ret = i2c_smbus_read_block_data(client, PMBUS_MFR_ID,
>> block_buffer);
>>> + if (ret < 0) {
>>> + dev_err(&client->dev, "failed to read manufacturer
>>> + id\n");
>>
>> Kind of pointless to declare a local 'dev' variable and not use it.
> We will drop it
>
>>
>>> + return ret;
>>> + }
>>> +
>>> + /* Refer to ltc4286 datasheet page 20
>>> + * the default manufacturer id is LTC
>>
>> Why "default" ?
> We will revise to
> /*
> * Refer to ltc4286 datasheet page 20
> * the manufacturer id is LTC
> */
>
>>
>>> + */
>>
>> Please use standard multi-line comments.
> We will revise to
> /*
> * Refer to ltc4286 datasheet page 20
> * the manufacturer id is LTC
> */
>
>>
>>> + if (ret != LTC4286_MFR_ID_SIZE ||
>>> + strncmp(block_buffer, "LTC", LTC4286_MFR_ID_SIZE)) {
>>> + dev_err(&client->dev, "unsupported manufacturer id\n");
>>> + return -ENODEV;
>>> + }
>>> +
>>> + ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL,
>> block_buffer);
>>> + if (ret < 0) {
>>> + dev_err(&client->dev, "failed to read manufacturer
>> model\n");
>>> + return ret;
>>> + }
>>
>> Why read the model if you don't do anything with it ?
> We will add comaprision here.
> for (mid = ltc4286_id; mid->name[0]; mid++) {
> if (!strncasecmp(mid->name, block_buffer, strlen(mid->name)))
> break;
> }
>
>>
>>> +
>>> + ret = of_property_read_u32(client->dev.of_node,
>> "rsense-micro-ohms",
>>> + &rsense);
>>> + if (ret < 0)
>>> + return ret;
>>> +
>>> + if (rsense == 0)
>>> + return -EINVAL;
>>> +
>>
>> There should be a default for systems not supporting devicetree.
> After confirming with vendor, they said there is no default rsesne for this chip
> The value for rsense depends on hardware engineer in each manufacturer
>

The _driver_ needs a default.

>>
>>> + info = &ltc4286_info;
>>> +
>>> + /* Default of VRANGE_SELECT = 1 */
>>> + if (device_property_read_bool(dev, "vrange_select_25p6")) {
>>> + /* Setup MFR1 CONFIG register bit 1 VRANGE_SELECT */
>>> + ret = i2c_smbus_read_word_data(client,
>> LTC4286_MFR_CONFIG1);
>>> + if (ret < 0) {
>>> + dev_err(&client->dev,
>>> + "failed to read manufacturer
>> configuration one\n");
>>> + return ret;
>>> + }
>>> +
>>> + ret &= ~VRANGE_SELECT; /* VRANGE_SELECT = 0, 25.6V */
>>> + i2c_smbus_write_word_data(client,
>> LTC4286_MFR_CONFIG1,
>>> + ret);
>>
>> Error check missing.
> ret = i2c_smbus_write_word_data(client, LTC4286_MFR_CONFIG1, ret);
> if (ret < 0) {
> dev_err(&client->dev, "failed to set vrange\n");
> return ret;
> }
>
>>
>>> +
>>> + info->m[PSC_VOLTAGE_IN] = 128;
>>> + info->m[PSC_VOLTAGE_OUT] = 128;
>>> + info->m[PSC_POWER] = 4 * rsense;
>>> + } else {
>>> + info->m[PSC_POWER] = rsense;
>>
>> This just takes the current configuration, and assumes it is the default.
>> That may not be correct. The chip may have been configured by the BIOS, or
>> manually.
> The MBR values are based on hardware design, so it must be set in initial stage
>
>>
>>> + }
>>> +
>>
>> The code assumes that there is only a single chip in the system, or that the
>> configuration of all chips is identical. This is not necessarily correct.
> If there are more than one LTC4286 or LTC4287 chips, user can add the configuration for different chips in dts file
>

"info" is a pointer to a static variable.

info = &ltc4286_info;

In this context, what you are saying above does not make sense. The
second chip's configuration will override the first chip's configuration.

info->m[PSC_POWER] = 4 * rsense;
...

No, sorry, this still does not make sense.

>>
>>> + info->m[PSC_CURRENT_OUT] = 1024 * rsense;
>>> +
>>> + return pmbus_do_probe(client, info); }
>>> +
>>> +static const struct i2c_device_id ltc4286_id[] = { { "ltc4286", ltc4286 },
>>> + { "ltc4287",
>> ltc4287
>>> +},
>>
>> Even if LTC4287 existed, assigning the ID here ...
> So do you recommend us to put this enum (enum chips { ltc4286, ltc4287 };) here?
>
>>
>>> + {} };
>>> +MODULE_DEVICE_TABLE(i2c, ltc4286_id);
>>> +
>>> +static const struct of_device_id ltc4286_of_match[] = {
>>> + { .compatible = "lltc,ltc4286" },
>>> + { .compatible = "lltc,ltc4287" },
>>
>> ... but not here defeats having it in the first place.
> So do you recommend us to not put this enum (enum chips { ltc4286, ltc4287 };) here?
>

Please read my comment. I am saying that it does not make sense to provide the chip ID
to i2c_device_id but not in of_device_id. Either add it do both if needed or not at
all. I am not telling which one, I am just asking for consistency.

However, as mentioned earlier, according to your code the chips supposedly have identical
functionality. Separate chip IDs (ltc4286 and ltc4287) therefore seem unnecessary (not
even counting the fact that ltc4287 still does not seem to exist).

>>
>>> + {}
>>> +};
>>
>> MODULE_DEVOCE_TABLE() missing.
> In v1 line 120
>
>>
>>> +
>>> +/* This is the driver that will be inserted */
>>
>> Useless comment
> We will drop it.
>
>>
>>> +static struct i2c_driver ltc4286_driver = {
>>> + .driver = {
>>> + .name = "ltc4286",
>>> + .of_match_table = ltc4286_of_match,
>>> + },
>>> + .probe = ltc4286_probe,
>>> + .id_table = ltc4286_id,
>>> +};
>>> +
>>> +module_i2c_driver(ltc4286_driver);
>>> +
>>> +MODULE_AUTHOR("Delphine CC Chiu
>> <[email protected]>");
>>> +MODULE_DESCRIPTION("PMBUS driver for LTC4286 and compatibles");
>>> +MODULE_LICENSE("GPL");
>>> --
>>> 2.17.1
>>>