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Message-Id: <d83cb66b-5cbf-ebb6-9ba9-13981d126360@linux.vnet.ibm.com>
Date: Tue, 13 Mar 2018 14:01:51 -0500
From: Eddie James <eajames@...ux.vnet.ibm.com>
To: Guenter Roeck <linux@...ck-us.net>, linux-hwmon@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, jdelvare@...e.com, joel@....id.au,
Christopher Bostic <cbostic@...ux.vnet.ibm.com>,
Andrew Jeffery <andrew@...id.au>
Subject: Re: [PATCH 2/2] hwmon: (ucd9000) Add debugfs attributes to provide
mfr_status
On 03/10/2018 10:50 AM, Guenter Roeck wrote:
> On 03/09/2018 11:19 AM, Eddie James wrote:
>> From: Christopher Bostic <cbostic@...ux.vnet.ibm.com>
>>
>> Expose the gpiN_fault fields of mfr_status as individual debugfs
>> attributes. This provides a way for users to be easily notified of gpi
>> faults. Also provide the whole mfr_status register in debugfs.
>>
>> Signed-off-by: Christopher Bostic <cbostic@...ux.vnet.ibm.com>
>> Signed-off-by: Andrew Jeffery <andrew@...id.au>
>> Signed-off-by: Eddie James <eajames@...ux.vnet.ibm.com>
>> ---
>> drivers/hwmon/pmbus/ucd9000.c | 172
>> +++++++++++++++++++++++++++++++++++++++++-
>> 1 file changed, 171 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/hwmon/pmbus/ucd9000.c
>> b/drivers/hwmon/pmbus/ucd9000.c
>> index e3a507f..297da0e 100644
>> --- a/drivers/hwmon/pmbus/ucd9000.c
>> +++ b/drivers/hwmon/pmbus/ucd9000.c
>> @@ -19,6 +19,7 @@
>> * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
>> */
>> +#include <linux/debugfs.h>
>> #include <linux/kernel.h>
>> #include <linux/module.h>
>> #include <linux/of_device.h>
>> @@ -36,6 +37,7 @@
>> #define UCD9000_NUM_PAGES 0xd6
>> #define UCD9000_FAN_CONFIG_INDEX 0xe7
>> #define UCD9000_FAN_CONFIG 0xe8
>> +#define UCD9000_MFR_STATUS 0xf3
>> #define UCD9000_GPIO_SELECT 0xfa
>> #define UCD9000_GPIO_CONFIG 0xfb
>> #define UCD9000_DEVICE_ID 0xfd
>> @@ -63,13 +65,22 @@
>> #define UCD901XX_NUM_GPIOS 26
>> #define UCD90910_NUM_GPIOS 26
>> +#define UCD9000_DEBUGFS_NAME_LEN 24
>> +#define UCD9000_GPI_COUNT 8
>> +
>> struct ucd9000_data {
>> u8 fan_data[UCD9000_NUM_FAN][I2C_SMBUS_BLOCK_MAX];
>> struct pmbus_driver_info info;
>> struct gpio_chip gpio;
>> + struct dentry *debugfs;
>> };
>> #define to_ucd9000_data(_info) container_of(_info, struct
>> ucd9000_data, info)
>> +struct ucd9000_debugfs_entry {
>> + struct i2c_client *client;
>> + u8 index;
>> +};
>> +
>> static int ucd9000_get_fan_config(struct i2c_client *client, int fan)
>> {
>> int fan_config = 0;
>> @@ -328,6 +339,156 @@ static int ucd9000_gpio_direction_output(struct
>> gpio_chip *gc,
>> val);
>> }
>> +#if IS_ENABLED(CONFIG_DEBUG_FS)
>> +static int ucd9000_get_mfr_status(struct i2c_client *client, u8
>> *buffer)
>> +{
>> + int ret = pmbus_set_page(client, 0);
>> +
>> + if (ret < 0)
>> + return ret;
>> +
>> + /*
>> + * With the ucd90120 and ucd90124 devices, this command
>> [MFR_STATUS]
>> + * is 2 bytes long (bits 0-15). With the ucd90240 this command
>> is 5
>> + * bytes long. With all other devices, it is 4 bytes long.
>> + */
>> + return i2c_smbus_read_block_data(client, UCD9000_MFR_STATUS,
>> buffer);
>> +}
>> +
>> +static int ucd9000_debugfs_show_mfr_status_bit(void *data, u64 *val)
>> +{
>> + struct ucd9000_debugfs_entry *entry = data;
>> + struct i2c_client *client = entry->client;
>> + u8 buffer[4];
>> + int ret;
>> +
>> + /*
>> + * This attribute is only created for devices that return 4
>> bytes for
>> + * status_mfr, so it's safe to call with 4-byte buffer.
>> + */
>> + ret = ucd9000_get_mfr_status(client, buffer);
>> + if (ret < 0) {
>> + dev_err(&client->dev, "Failed to read mfr status. rc:%d\n",
>> + ret);
>> +
>> + return ret;
>> + }
>> +
>> + /*
>> + * Attribute only created for devices with gpi fault bits at bits
>> + * 16-23, which is the second byte of the response.
>> + */
>> + *val = !!(buffer[1] & BIT(entry->index));
>> +
>> + return 0;
>> +}
>> +DEFINE_DEBUGFS_ATTRIBUTE(ucd9000_debugfs_mfr_status_bit,
>> + ucd9000_debugfs_show_mfr_status_bit, NULL, "%1lld\n");
>> +
>> +static int ucd9000_debugfs_show_mfr_status_word2(void *data, u64 *val)
>> +{
>> + struct i2c_client *client = data;
>> + __be16 buffer;
>> + int ret;
>> +
>> + ret = ucd9000_get_mfr_status(client, (u8 *)&buffer);
>> + if (ret < 0) {
>> + dev_err(&client->dev, "Failed to read mfr status. rc:%d\n",
>> + ret);
>> +
>> + return ret;
>> + }
>> +
>> + *val = be16_to_cpu(buffer);
>> +
>> + return 0;
>> +}
>> +DEFINE_DEBUGFS_ATTRIBUTE(ucd9000_debugfs_mfr_status_word2,
>> + ucd9000_debugfs_show_mfr_status_word2, NULL,
>> + "%04llx\n");
>> +
>> +static int ucd9000_debugfs_show_mfr_status_word4(void *data, u64 *val)
>> +{
>> + struct i2c_client *client = data;
>> + __be32 buffer;
>> + int ret;
>> +
>> + ret = ucd9000_get_mfr_status(client, (u8 *)&buffer);
>> + if (ret < 0) {
>> + dev_err(&client->dev, "Failed to read mfr status. rc:%d\n",
>> + ret);
>> +
>> + return ret;
>> + }
>> +
>> + *val = be32_to_cpu(buffer);
>> +
>> + return 0;
>> +}
>> +DEFINE_DEBUGFS_ATTRIBUTE(ucd9000_debugfs_mfr_status_word4,
>> + ucd9000_debugfs_show_mfr_status_word4, NULL,
>> + "%08llx\n");
>> +
>> +static int ucd9000_init_debugfs(struct i2c_client *client,
>> + const struct i2c_device_id *mid,
>> + struct ucd9000_data *data)
>> +{
>> + struct dentry *debugfs;
>> + struct ucd9000_debugfs_entry *entries;
>> + int i;
>> + char name[UCD9000_DEBUGFS_NAME_LEN];
>> +
>> + debugfs = pmbus_get_debugfs_dir(client);
>> + if (!debugfs)
>> + return -ENOENT;
>> +
>> + data->debugfs = debugfs_create_dir(client->name, debugfs);
>> + if (!data->debugfs)
>> + return -ENOENT;
>> +
>> + /*
>> + * Of the chips this driver supports, only the UCD9090, UCD90160,
>> + * and UCD90910 report GPI faults in their MFR_STATUS register,
>> so only
>> + * create the GPI fault debugfs attributes for those chips.
>> + */
>> + if (mid->driver_data == ucd9090 || mid->driver_data == ucd90160 ||
>> + mid->driver_data == ucd90910) {
>> + entries = devm_kzalloc(&client->dev,
>> + sizeof(*entries) * UCD9000_GPI_COUNT,
>> + GFP_KERNEL);
>> + if (!entries)
>> + return -ENOMEM;
>> +
>> + for (i = 0; i < UCD9000_GPI_COUNT; i++) {
>> + entries[i].client = client;
>> + entries[i].index = i;
>> + scnprintf(name, UCD9000_DEBUGFS_NAME_LEN,
>> + "gpi%d_alarm", i + 1);
>> + debugfs_create_file(name, 0444, data->debugfs,
>> + &entries[i],
>> + &ucd9000_debugfs_mfr_status_bit);
>> + }
>> +
>> + scnprintf(name, UCD9000_DEBUGFS_NAME_LEN, "mfr_status");
>> + debugfs_create_file(name, 0444, data->debugfs, client,
>> + &ucd9000_debugfs_mfr_status_word4);
>> + } else if (mid->driver_data == ucd90120 ||
>> + mid->driver_data == ucd90124) {
>> + scnprintf(name, UCD9000_DEBUGFS_NAME_LEN, "mfr_status");
>> + debugfs_create_file(name, 0444, data->debugfs, client,
>> + &ucd9000_debugfs_mfr_status_word2);
>> + }
>> +
>> + return 0;
>> +}
>
> Is all that complexity really worth it ? Why not just read the
> manufacturing
> status as byte string into a buffer and use hexdump to pront it, no
> matter how
> many bytes are actually returned ? This would also be less error
> prone, and
> automatically support future chips.
Hm, well then we have the additional complexity of setting up custom
debugfs file operations to show the binary data instead of just using
DEFINE_DEBUGFS_ATTRIBUTE. Plus, at some point someone has to interpret
it as either a word, half-word, or 5 bytes chunk. Where better to do it
than the driver, as this is hw-dependent?
I could just use one function and do a byte-swap based on data length in
a loop within #ifdef LITTLE_ENDIAN, but that's a little messy. It will
handle all the cases though. What do you think?
Thanks,
Eddie
>
> Thanks,
> Guenter
>
>> +#else
>> +static int ucd9000_init_debugfs(struct i2c_client *client,
>> + struct ucd9000_data *data)
>> +{
>> + return 0;
>> +}
>> +#endif /* IS_ENABLED(CONFIG_DEBUG_FS) */
>> +
>> static int ucd9000_probe(struct i2c_client *client,
>> const struct i2c_device_id *id)
>> {
>> @@ -483,7 +644,16 @@ static int ucd9000_probe(struct i2c_client *client,
>> return ret;
>> }
>> - return pmbus_do_probe(client, mid, info);
>> + ret = pmbus_do_probe(client, mid, info);
>> + if (ret)
>> + return ret;
>> +
>> + ret = ucd9000_init_debugfs(client, mid, data);
>> + if (ret)
>> + dev_warn(&client->dev, "Failed to register debugfs: %d\n",
>> + ret);
>> +
>> + return 0;
>> }
>> /* This is the driver that will be inserted */
>>
>
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