RE: [PATCH v3 2/2] riscv: Add support to determine no. of L2 cache way enabled

[Yash Shah]

> -----Original Message-----
> From: Anup Patel <anup@xxxxxxxxxxxxxx>
> Sent: 14 January 2020 10:30
> To: Yash Shah <yash.shah@xxxxxxxxxx>
> Cc: Paul Walmsley ( Sifive) <paul.walmsley@xxxxxxxxxx>; Palmer Dabbelt
> <palmer@xxxxxxxxxxx>; Albert Ou <aou@xxxxxxxxxxxxxxxxx>; Allison
> Randal <allison@xxxxxxxxxxx>; Alexios Zavras <alexios.zavras@xxxxxxxxx>;
> Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>; Thomas Gleixner
> <tglx@xxxxxxxxxxxxx>; bp@xxxxxxx; linux-riscv <linux-
> riscv@xxxxxxxxxxxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx List <linux-
> kernel@xxxxxxxxxxxxxxx>; Sachin Ghadi <sachin.ghadi@xxxxxxxxxx>
> Subject: Re: [PATCH v3 2/2] riscv: Add support to determine no. of L2 cache
> way enabled
> 
> On Mon, Jan 13, 2020 at 12:09 PM Yash Shah <yash.shah@xxxxxxxxxx> wrote:
> >
> > In order to determine the number of L2 cache ways enabled at runtime,
> > implement a private attribute ("number_of_ways_enabled"). Reading this
> > attribute returns the number of enabled L2 cache ways at runtime.
> >
> > Using riscv_set_cacheinfo_ops() hook a custom function, that returns
> > this private attribute, to the generic ops structure which is used by
> > cache_get_priv_group() in cacheinfo framework.
> >
> > Signed-off-by: Yash Shah <yash.shah@xxxxxxxxxx>
> > ---
> >  drivers/soc/sifive/sifive_l2_cache.c | 38
> > ++++++++++++++++++++++++++++++++++++
> >  include/soc/sifive/sifive_l2_cache.h |  2 ++
> >  2 files changed, 40 insertions(+)
> >
> > diff --git a/drivers/soc/sifive/sifive_l2_cache.c
> > b/drivers/soc/sifive/sifive_l2_cache.c
> > index a506939..8741885 100644
> > --- a/drivers/soc/sifive/sifive_l2_cache.c
> > +++ b/drivers/soc/sifive/sifive_l2_cache.c
> > @@ -9,6 +9,8 @@
> >  #include <linux/interrupt.h>
> >  #include <linux/of_irq.h>
> >  #include <linux/of_address.h>
> > +#include <linux/device.h>
> > +#include <asm/cacheinfo.h>
> >  #include <soc/sifive/sifive_l2_cache.h>
> >
> >  #define SIFIVE_L2_DIRECCFIX_LOW 0x100 @@ -31,6 +33,7 @@
> >
> >  static void __iomem *l2_base;
> >  static int g_irq[SIFIVE_L2_MAX_ECCINTR];
> > +static struct riscv_cacheinfo_ops l2_cache_ops;
> >
> >  enum {
> >         DIR_CORR = 0,
> > @@ -107,6 +110,38 @@ int unregister_sifive_l2_error_notifier(struct
> > notifier_block *nb)  }
> > EXPORT_SYMBOL_GPL(unregister_sifive_l2_error_notifier);
> >
> > +int sifive_l2_largest_wayenabled(void)
> > +{
> > +       return readl(l2_base + SIFIVE_L2_WAYENABLE); }
> 
> The sifine_l2_largest_wayenabled() is not called from anywhere else so
> make it static and rename it to l2_largest_wayenabled().

Sure will do that in v4

> 
> > +
> > +static ssize_t number_of_ways_enabled_show(struct device *dev,
> > +                                          struct device_attribute *attr,
> > +                                          char *buf) {
> > +       return sprintf(buf, "%u\n", sifive_l2_largest_wayenabled()); }
> > +
> > +static DEVICE_ATTR_RO(number_of_ways_enabled);
> > +
> > +static struct attribute *priv_attrs[] = {
> > +       &dev_attr_number_of_ways_enabled.attr,
> > +       NULL,
> > +};
> > +
> > +static const struct attribute_group priv_attr_group = {
> > +       .attrs = priv_attrs,
> > +};
> > +
> > +const struct attribute_group *l2_get_priv_group(struct cacheinfo
> > +*this_leaf) {
> > +       /* We want to use private group for L2 cache only */
> > +       if (this_leaf->level == 2)
> > +               return &priv_attr_group;
> > +       else
> > +               return NULL;
> > +}
> > +
> >  static irqreturn_t l2_int_handler(int irq, void *device)  {
> >         unsigned int add_h, add_l;
> > @@ -170,6 +205,9 @@ static int __init sifive_l2_init(void)
> >
> >         l2_config_read();
> >
> > +       l2_cache_ops.get_priv_group = l2_get_priv_group;
> > +       riscv_set_cacheinfo_ops(&l2_cache_ops);
> > +
> >  #ifdef CONFIG_DEBUG_FS
> >         setup_sifive_debug();
> >  #endif
> > diff --git a/include/soc/sifive/sifive_l2_cache.h
> > b/include/soc/sifive/sifive_l2_cache.h
> > index 92ade10..55feff5 100644
> > --- a/include/soc/sifive/sifive_l2_cache.h
> > +++ b/include/soc/sifive/sifive_l2_cache.h
> > @@ -10,6 +10,8 @@
> >  extern int register_sifive_l2_error_notifier(struct notifier_block
> > *nb);  extern int unregister_sifive_l2_error_notifier(struct
> > notifier_block *nb);
> >
> > +int sifive_l2_largest_wayenabled(void);
> > +
> 
> You can drop the sifive_l2_largest_wayenabled() declaration from here.
> 
> >  #define SIFIVE_L2_ERR_TYPE_CE 0
> >  #define SIFIVE_L2_ERR_TYPE_UE 1
> >
> > --
> > 2.7.4
> >
> 
> Apart from above it looks good.
> 
> Reviewed-by: Anup Patel <anup@xxxxxxxxxxxxxx>

Thanks.

- Yash

> 
> Regards,
> Anup