Subject: Re: [PATCH v3] hwmon: (ibmpowernv) pretty print labels

From: Guenter Roeck <[email-masked]>
Date: Wed, 08 Apr 2015 06:26:50 -0700

On 04/08/2015 12:00 AM, Cédric Le Goater wrote:
> The new OPAL device tree adds a few properties which can be used to add
> extra information on the sensor label.
>
> In the case of a cpu core sensor, the firmware exposes the physical
> identifier of the core in the "ibm,pir" property. The driver
> translates this identifier in a linux cpu number and prints out a
> range corresponding to the hardware threads of the core (as they
> share the same sensor).
>
> The numbering gives a hint on the localization of the core in the
> system (which socket, which chip).
>
> Signed-off-by: Cédric Le Goater <[email-masked]>
> ---
>
>   Changes since v2:
>
>   - fix bogus logical cpu retrieval
>   - use 'threads_per_core' to print out cpu range
>
>   Changes since v1:
>
>   - check cpu validity before printing out the attribute label.
>     if invalid, use a "phy" prefix to distinguish a linux cpu
>     number from a physical cpu number.
>
>   drivers/hwmon/ibmpowernv.c |   43 +++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 43 insertions(+)
>
> Index: linux.git/drivers/hwmon/ibmpowernv.c
> ===================================================================
> --- linux.git.orig/drivers/hwmon/ibmpowernv.c
> +++ linux.git/drivers/hwmon/ibmpowernv.c
> @@ -30,6 +30,7 @@
>   #include <linux/platform_device.h>
>   #include <asm/opal.h>
>   #include <linux/err.h>
> +#include <asm/cputhreads.h>
>
>   #define MAX_ATTR_LEN	32
>   #define MAX_LABEL_LEN	64
> @@ -110,12 +111,54 @@ static ssize_t show_label(struct device
>   	return sprintf(buf, "%s\n", sdata->label);
>   }
>
> +static int __init get_logical_cpu(unsigned int hwcpu)
> +{
> +	int cpu;
> +
> +	for_each_possible_cpu(cpu)
> +		if (get_hard_smp_processor_id(cpu) == hwcpu)
> +			return cpu;
> +
> +	pr_err("%s: could not find a cpu with physical id 0x%x\n",
> +	       __func__, hwcpu);

I like moving this into a function, but I really dislike this error
message. If the devicetree data is wrong/bad, the log and the console
will be clogged with that message. And the user will not be able
to do anything about it.

Guenter

> +	return -ENOENT;
> +}
> +
>   static void __init make_sensor_label(struct device_node *np,
>   		    struct sensor_data *sdata, const char *label)
>   {
> +	u32 id;
>   	size_t n;
>
>   	n = snprintf(sdata->label, sizeof(sdata->label), "%s", label);
> +
> +	/*
> +	 * Core temp pretty print
> +	 */
> +	if (!of_property_read_u32(np, "ibm,pir", &id)) {
> +		int cpuid = get_logical_cpu(id);
> +
> +		if (cpuid >= 0)
> +			/*
> +			 * The digital thermal sensors are associated
> +			 * with a core. Let's print out the range of
> +			 * cpu ids corresponding to the hardware
> +			 * threads of the core.
> +			 */
> +			n += snprintf(sdata->label + n,
> +				      sizeof(sdata->label) - n, " %d-%d",
> +				      cpuid, cpuid + threads_per_core - 1);
> +		else
> +			n += snprintf(sdata->label + n,
> +				      sizeof(sdata->label) - n, " phy%d", id);
> +	}
> +
> +	/*
> +	 * Membuffer pretty print
> +	 */
> +	if (!of_property_read_u32(np, "ibm,chip-id", &id))
> +		n += snprintf(sdata->label + n, sizeof(sdata->label) - n,
> +			      " %d", id & 0xffff);
>   }
>
>   static int get_sensor_index_attr(const char *name, u32 *index,
>
>