linux-kernel - Re: [PATCH v3 2/2] riscv: Add support to determine no. of L2 cache way enabled

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Message-ID: <CAAhSdy2QvF+U0eJ1XMc8L5gJB5e_9_XUoQpg8pVof+kxxJ5avg@mail.gmail.com>
Date:   Tue, 14 Jan 2020 10:30:16 +0530
From:   Anup Patel <anup@...infault.org>
To:     Yash Shah <yash.shah@...ive.com>
Cc:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Allison Randal <allison@...utok.net>,
        Alexios Zavras <alexios.zavras@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Gleixner <tglx@...utronix.de>, bp@...e.de,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>,
        Sachin Ghadi <sachin.ghadi@...ive.com>
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@...ive.com> 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@...ive.com>
> ---
>  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().

> +
> +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@...infault.org>

Regards,
Anup