Re: [PATCH v2 01/10] hwmon: (fam15h_power) Refactor attributes for dynamically added

[Guenter Roeck <linux@roeck-us.net>]

On Mon, Oct 26, 2015 at 09:58:45AM +0800, Huang Rui wrote:
> On Fri, Oct 23, 2015 at 06:42:20AM -0700, Guenter Roeck wrote:
> > On 10/19/2015 07:28 PM, Huang Rui wrote:
> > >Attributes depend on the CPU model the driver gets loaded on.
> > >Therefore, add those attributes dynamically at init time. This is more
> > >flexible to control the different attributes on different platforms.
> > >
> > >Suggestedy-by: Borislav Petkov <bp@alien8.de>
> > >Signed-off-by: Huang Rui <ray.huang@amd.com>
> > >Cc: Guenter Roeck <linux@roeck-us.net>
> > >Cc: Peter Zijlstra <peterz@infradead.org>
> > >Cc: Ingo Molnar <mingo@kernel.org>
> > >---
> > >  drivers/hwmon/fam15h_power.c | 70 ++++++++++++++++++++++++++++----------------
> > >  1 file changed, 45 insertions(+), 25 deletions(-)
> > >
> > >diff --git a/drivers/hwmon/fam15h_power.c b/drivers/hwmon/fam15h_power.c
> > >index e80ee23..41d022e 100644
> > >--- a/drivers/hwmon/fam15h_power.c
> > >+++ b/drivers/hwmon/fam15h_power.c
> > >@@ -41,12 +41,17 @@ MODULE_LICENSE("GPL");
> > >  #define REG_TDP_RUNNING_AVERAGE		0xe0
> > >  #define REG_TDP_LIMIT3			0xe8
> > >
> > >+#define FAM15H_MIN_NUM_ATTRS		2
> > >+#define FAM15H_NUM_GROUPS		2
> > >+
> > >  struct fam15h_power_data {
> > >  	struct pci_dev *pdev;
> > >  	unsigned int tdp_to_watts;
> > >  	unsigned int base_tdp;
> > >  	unsigned int processor_pwr_watts;
> > >  	unsigned int cpu_pwr_sample_ratio;
> > >+	const struct attribute_group *fam15h_power_groups[FAM15H_NUM_GROUPS];
> > >+	struct attribute_group fam15h_power_group;
> > >  };
> > >
> > >  static ssize_t show_power(struct device *dev,
> > >@@ -105,29 +110,31 @@ static ssize_t show_power_crit(struct device *dev,
> > >  }
> > >  static DEVICE_ATTR(power1_crit, S_IRUGO, show_power_crit, NULL);
> > >
> > >-static umode_t fam15h_power_is_visible(struct kobject *kobj,
> > >-				       struct attribute *attr,
> > >-				       int index)
> > >+static int fam15h_power_init_attrs(struct pci_dev *pdev,
> > >+				   struct fam15h_power_data *data)
> > >  {
> > >-	/* power1_input is only reported for Fam15h, Models 00h-0fh */
> > >-	if (attr == &dev_attr_power1_input.attr &&
> > >-	   (boot_cpu_data.x86 != 0x15 || boot_cpu_data.x86_model > 0xf))
> > >-		return 0;
> > >+	int n = FAM15H_MIN_NUM_ATTRS;
> > >+	struct attribute **fam15h_power_attrs;
> > >
> > >-	return attr->mode;
> > >-}
> > >+	if (boot_cpu_data.x86 == 0x15 && boot_cpu_data.x86_model <= 0xf)
> > >+		n += 1;
> > >
> > >-static struct attribute *fam15h_power_attrs[] = {
> > >-	&dev_attr_power1_input.attr,
> > >-	&dev_attr_power1_crit.attr,
> > >-	NULL
> > >-};
> > >+	fam15h_power_attrs = devm_kcalloc(&pdev->dev, n,
> > >+					  sizeof(*fam15h_power_attrs),
> > >+					  GFP_KERNEL);
> > >
> > >-static const struct attribute_group fam15h_power_group = {
> > >-	.attrs = fam15h_power_attrs,
> > >-	.is_visible = fam15h_power_is_visible,
> > >-};
> > >-__ATTRIBUTE_GROUPS(fam15h_power);
> > >+	if (!fam15h_power_attrs)
> > >+		return -ENOMEM;
> > >+
> > >+	n = 0;
> > >+	fam15h_power_attrs[n++] = &dev_attr_power1_crit.attr;
> > >+	if (boot_cpu_data.x86 == 0x15 && boot_cpu_data.x86_model <= 0xf)
> > >+		fam15h_power_attrs[n++] = &dev_attr_power1_input.attr;
> > >+
> > >+	data->fam15h_power_group.attrs = fam15h_power_attrs;
> > >+
> > >+	return 0;
> > >+}
> > >
> > >  static bool should_load_on_this_node(struct pci_dev *f4)
> > >  {
> > >@@ -186,11 +193,12 @@ static int fam15h_power_resume(struct pci_dev *pdev)
> > >  #define fam15h_power_resume NULL
> > >  #endif
> > >
> > >-static void fam15h_power_init_data(struct pci_dev *f4,
> > >-					     struct fam15h_power_data *data)
> > >+static int fam15h_power_init_data(struct pci_dev *f4,
> > >+				  struct fam15h_power_data *data)
> > >  {
> > >  	u32 val, eax, ebx, ecx, edx;
> > >  	u64 tmp;
> > >+	int ret;
> > >
> > >  	pci_read_config_dword(f4, REG_PROCESSOR_TDP, &val);
> > >  	data->base_tdp = val >> 16;
> > >@@ -211,11 +219,15 @@ static void fam15h_power_init_data(struct pci_dev *f4,
> > >  	/* convert to microWatt */
> > >  	data->processor_pwr_watts = (tmp * 15625) >> 10;
> > >
> > >+	ret = fam15h_power_init_attrs(f4, data);
> > >+	if (ret)
> > >+		return ret;
> > >+
> > >  	cpuid(0x80000007, &eax, &ebx, &ecx, &edx);
> > >
> > >  	/* CPUID Fn8000_0007:EDX[12] indicates to support accumulated power */
> > >  	if (!(edx & BIT(12)))
> > >-		return;
> > >+		return 0;
> > >
> > >  	/*
> > >  	 * determine the ratio of the compute unit power accumulator
> > >@@ -223,14 +235,17 @@ static void fam15h_power_init_data(struct pci_dev *f4,
> > >  	 * Fn8000_0007:ECX
> > >  	 */
> > >  	data->cpu_pwr_sample_ratio = ecx;
> > >+
> > >+	return 0;
> > >  }
> > >
> > >  static int fam15h_power_probe(struct pci_dev *pdev,
> > >-					const struct pci_device_id *id)
> > >+			      const struct pci_device_id *id)
> > >  {
> > >  	struct fam15h_power_data *data;
> > >  	struct device *dev = &pdev->dev;
> > >  	struct device *hwmon_dev;
> > >+	int ret;
> > >
> > >  	/*
> > >  	 * though we ignore every other northbridge, we still have to
> > >@@ -246,12 +261,17 @@ static int fam15h_power_probe(struct pci_dev *pdev,
> > >  	if (!data)
> > >  		return -ENOMEM;
> > >
> > >-	fam15h_power_init_data(pdev, data);
> > >+	ret = fam15h_power_init_data(pdev, data);
> > >+	if (ret)
> > >+		return ret;
> > >+
> > >  	data->pdev = pdev;
> > >
> > >+	data->fam15h_power_groups[0] = &data->fam15h_power_group;
> > >+
> > >  	hwmon_dev = devm_hwmon_device_register_with_groups(dev, "fam15h_power",
> > >  							   data,
> > >-							   fam15h_power_groups);
> > >+							   (const struct attribute_group **)&data->fam15h_power_groups);
> > 
> > Why this typecast ? It should not be needed.
> > 
> 
> That's because there will be a warning without the typecast.
> 
> Expected 'const struct attribute_group **', but current type is 'const
> struct attribute_group * (*)[2]'.
> 

Maybe then either use data->fam15h_power_groups (no &) or
&data->fam15h_power_groups[0].

On a side note, the "fam15h_" prefix in the variable name is really
unnecessary unless there are some other groups in the same data structure.
Even the "power_" prefix doesn't really add any value unless there
are other groups.

Thanks,
Guenter
	
> ---
>   CC [M]  /home/ray/tip/drivers/hwmon/fam15h_power.o
> /home/ray/tip/drivers/hwmon/fam15h_power.c: In function ‘fam15h_power_probe’:
> /home/ray/tip/drivers/hwmon/fam15h_power.c:481:11: warning: passing argument 4 of ‘devm_hwmon_device_register_with_groups’ from incompatible pointer type [enabled by default]
>            &data->fam15h_power_groups);
>            ^
> In file included from /home/ray/tip/drivers/hwmon/fam15h_power.c:22:0:
> include/linux/hwmon.h:26:1: note: expected ‘const struct attribute_group **’ but argument is of type ‘const struct attribute_group * (*)[2]’
>  devm_hwmon_device_register_with_groups(struct device *dev, const char *name,
>  ^
> ---
> 
> Thanks,
> Rui