2023-05-16 20:38:14

by Yazen Ghannam

Subject: [PATCH 5/6] hwmon: (k10temp) Define helper function to read CCD temp

The CCD temperature register is read in two places. These reads are done
using an AMD SMN access, and a number of parameters are needed for the
operation.

Move the SMN access and parameter gathering into a helper function in
order to simply the code flow. This also has a benefit of centralizing
the hardware register access in a single place in case fixes or special
decoding is required.

Signed-off-by: Yazen Ghannam <[email protected]>
---
drivers/hwmon/k10temp.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/hwmon/k10temp.c b/drivers/hwmon/k10temp.c
index 6ea1fa62b7c1..06af1fe38af7 100644
--- a/drivers/hwmon/k10temp.c
+++ b/drivers/hwmon/k10temp.c
@@ -150,6 +150,18 @@ static void read_tempreg_nb_zen(struct pci_dev *pdev, u32 *regval)
*regval = 0;
}

+static int read_ccd_temp_reg(struct k10temp_data *data, int ccd, u32 *regval)
+{
+ u16 node_id = amd_pci_dev_to_node_id(data->pdev);
+ u32 tmp;
+
+ if (amd_smn_read(node_id, ZEN_CCD_TEMP(data->ccd_offset, ccd), &tmp))
+ return -EINVAL;
+
+ *regval = tmp;
+ return 0;
+}
+
static long get_raw_temp(struct k10temp_data *data)
{
u32 regval;
@@ -214,9 +226,7 @@ static int k10temp_read_temp(struct device *dev, u32 attr, int channel,
*val = 0;
break;
case 2 ... 13: /* Tccd{1-12} */
- if (amd_smn_read(amd_pci_dev_to_node_id(data->pdev),
- ZEN_CCD_TEMP(data->ccd_offset, channel - 2),
- &regval))
+ if (read_ccd_temp_reg(data, channel - 2, &regval))
return -EINVAL;

*val = (regval & ZEN_CCD_TEMP_MASK) * 125 - 49000;
@@ -376,8 +386,7 @@ static void k10temp_get_ccd_support(struct pci_dev *pdev,
int i;

for (i = 0; i < limit; i++) {
- if (amd_smn_read(amd_pci_dev_to_node_id(pdev),
- ZEN_CCD_TEMP(data->ccd_offset, i), &regval))
+ if (read_ccd_temp_reg(data, i, &regval))
continue;

if (regval & ZEN_CCD_TEMP_VALID)
--
2.34.1

2023-05-17 13:10:33

by Guenter Roeck

Subject: Re: [PATCH 5/6] hwmon: (k10temp) Define helper function to read CCD temp

On Tue, May 16, 2023 at 03:24:29PM -0500, Yazen Ghannam wrote:
> The CCD temperature register is read in two places. These reads are done
> using an AMD SMN access, and a number of parameters are needed for the
> operation.
>
> Move the SMN access and parameter gathering into a helper function in
> order to simply the code flow. This also has a benefit of centralizing
> the hardware register access in a single place in case fixes or special
> decoding is required.
>
> Signed-off-by: Yazen Ghannam <[email protected]>
> ---
> drivers/hwmon/k10temp.c | 19 ++++++++++++++-----
> 1 file changed, 14 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/hwmon/k10temp.c b/drivers/hwmon/k10temp.c
> index 6ea1fa62b7c1..06af1fe38af7 100644
> --- a/drivers/hwmon/k10temp.c
> +++ b/drivers/hwmon/k10temp.c
> @@ -150,6 +150,18 @@ static void read_tempreg_nb_zen(struct pci_dev *pdev, u32 *regval)
> *regval = 0;
> }
>
> +static int read_ccd_temp_reg(struct k10temp_data *data, int ccd, u32 *regval)
> +{
> + u16 node_id = amd_pci_dev_to_node_id(data->pdev);
> + u32 tmp;
> +
> + if (amd_smn_read(node_id, ZEN_CCD_TEMP(data->ccd_offset, ccd), &tmp))
> + return -EINVAL;

As mentioned before, this is not appropriate. The error code
from amd_smn_read() should be returned.

> +
> + *regval = tmp;

This seems pointless. Why not just pass regval as parameter
to amd_smn_read() ?

This function should be reduced to

return amd_smn_read(node_id, ZEN_CCD_TEMP(data->ccd_offset, ccd), regval));

> + return 0;
> +}
> +
> static long get_raw_temp(struct k10temp_data *data)
> {
> u32 regval;
> @@ -214,9 +226,7 @@ static int k10temp_read_temp(struct device *dev, u32 attr, int channel,
> *val = 0;
> break;
> case 2 ... 13: /* Tccd{1-12} */
> - if (amd_smn_read(amd_pci_dev_to_node_id(data->pdev),
> - ZEN_CCD_TEMP(data->ccd_offset, channel - 2),
> - &regval))
> + if (read_ccd_temp_reg(data, channel - 2, &regval))
> return -EINVAL;

Now this is really wrong, no matter what. Why bother replacing the
error code in read_ccd_temp_reg() only to replace it again ?

>
> *val = (regval & ZEN_CCD_TEMP_MASK) * 125 - 49000;
> @@ -376,8 +386,7 @@ static void k10temp_get_ccd_support(struct pci_dev *pdev,
> int i;
>
> for (i = 0; i < limit; i++) {
> - if (amd_smn_read(amd_pci_dev_to_node_id(pdev),
> - ZEN_CCD_TEMP(data->ccd_offset, i), &regval))
> + if (read_ccd_temp_reg(data, i, &regval))
> continue;
>
> if (regval & ZEN_CCD_TEMP_VALID)
> --
> 2.34.1
>

2023-05-17 14:17:14

by Yazen Ghannam

Subject: Re: [PATCH 5/6] hwmon: (k10temp) Define helper function to read CCD temp

On 5/17/23 8:30 AM, Guenter Roeck wrote:
> On Tue, May 16, 2023 at 03:24:29PM -0500, Yazen Ghannam wrote:
>> The CCD temperature register is read in two places. These reads are done
>> using an AMD SMN access, and a number of parameters are needed for the
>> operation.
>>
>> Move the SMN access and parameter gathering into a helper function in
>> order to simply the code flow. This also has a benefit of centralizing
>> the hardware register access in a single place in case fixes or special
>> decoding is required.
>>
>> Signed-off-by: Yazen Ghannam <[email protected]>
>> ---
>> drivers/hwmon/k10temp.c | 19 ++++++++++++++-----
>> 1 file changed, 14 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/hwmon/k10temp.c b/drivers/hwmon/k10temp.c
>> index 6ea1fa62b7c1..06af1fe38af7 100644
>> --- a/drivers/hwmon/k10temp.c
>> +++ b/drivers/hwmon/k10temp.c
>> @@ -150,6 +150,18 @@ static void read_tempreg_nb_zen(struct pci_dev *pdev, u32 *regval)
>> *regval = 0;
>> }
>>
>> +static int read_ccd_temp_reg(struct k10temp_data *data, int ccd, u32 *regval)
>> +{
>> + u16 node_id = amd_pci_dev_to_node_id(data->pdev);
>> + u32 tmp;
>> +
>> + if (amd_smn_read(node_id, ZEN_CCD_TEMP(data->ccd_offset, ccd), &tmp))
>> + return -EINVAL;
>
> As mentioned before, this is not appropriate. The error code
> from amd_smn_read() should be returned.
>

Okay, will do.

>> +
>> + *regval = tmp;
>
> This seems pointless. Why not just pass regval as parameter
> to amd_smn_read() ?
>
> This function should be reduced to
>
> return amd_smn_read(node_id, ZEN_CCD_TEMP(data->ccd_offset, ccd), regval));
>

Yes, will do. I think I got carried away with the "don't save invalid
value" idea. But this isn't necessary if the caller checks the return
code and avoids using the value.

>> + return 0;
>> +}
>> +
>> static long get_raw_temp(struct k10temp_data *data)
>> {
>> u32 regval;
>> @@ -214,9 +226,7 @@ static int k10temp_read_temp(struct device *dev, u32 attr, int channel,
>> *val = 0;
>> break;
>> case 2 ... 13: /* Tccd{1-12} */
>> - if (amd_smn_read(amd_pci_dev_to_node_id(data->pdev),
>> - ZEN_CCD_TEMP(data->ccd_offset, channel - 2),
>> - &regval))
>> + if (read_ccd_temp_reg(data, channel - 2, &regval))
>> return -EINVAL;
>
> Now this is really wrong, no matter what. Why bother replacing the
> error code in read_ccd_temp_reg() only to replace it again ?
>

Understood. Will fix like the other places.

Thanks,
Yazen