Re: [PATCH v1 05/30] soc: sifive: l2 cache: Convert to platform driver

[Emil Renner Berthing <emil.renner.berthing@xxxxxxxxxxxxx>]

On Thu, 29 Sept 2022 at 19:59, Ben Dooks <ben.dooks@xxxxxxxxxx> wrote:
>
> On 29/09/2022 15:32, Hal Feng wrote:
> > From: Emil Renner Berthing <kernel@xxxxxxxx>
> >
> > This converts the driver to use the builtin_platform_driver_probe macro
> > to initialize the driver. This macro ends up calling device_initcall as
> > was used previously, but also allocates a platform device which gives us
> > access to much nicer APIs such as platform_ioremap_resource,
> > platform_get_irq and dev_err_probe.
>
> This is useful, but also there are other changes currently being sorted
> out by Zong Li (cc'd into this message) which have already been reviewed
> and are hopefully queued for the next kernel release.
>
> > Signed-off-by: Emil Renner Berthing <kernel@xxxxxxxx>
> > Signed-off-by: Hal Feng <hal.feng@xxxxxxxxxxxxxxxxxxxxxx>

I'm ok with something like this being merged, but please note that if
we ever want to support the JH7100 which uses registers in this
peripheral to flush the cache for its non-coherent DMAs then this
driver needs to be loaded before other peripherals or we will trigger
the 2nd warning in arch/riscv/mm/dma-noncoherent.c. I'm not sure we
can do that when it's a platform driver. See this patch for an
alternative to support the JH71x0s:
https://github.com/esmil/linux/commit/9c5b29da56ae29159c9572c5bb195fe3a1b535c5

/Emil

> >   drivers/soc/sifive/sifive_l2_cache.c | 79 ++++++++++++++--------------
> >   1 file changed, 40 insertions(+), 39 deletions(-)
> >
> > diff --git a/drivers/soc/sifive/sifive_l2_cache.c b/drivers/soc/sifive/sifive_l2_cache.c
> > index 59640a1d0b28..010d612f7420 100644
> > --- a/drivers/soc/sifive/sifive_l2_cache.c
> > +++ b/drivers/soc/sifive/sifive_l2_cache.c
> > @@ -7,9 +7,9 @@
> >    */
> >   #include <linux/debugfs.h>
> >   #include <linux/interrupt.h>
> > -#include <linux/of_irq.h>
> > -#include <linux/of_address.h>
> > -#include <linux/device.h>
> > +#include <linux/io.h>
> > +#include <linux/mod_devicetable.h>
> > +#include <linux/platform_device.h>
> >   #include <asm/cacheinfo.h>
> >   #include <soc/sifive/sifive_l2_cache.h>
> >
> > @@ -96,12 +96,6 @@ static void l2_config_read(void)
> >       pr_info("L2CACHE: Index of the largest way enabled: %d\n", regval);
> >   }
> >
> > -static const struct of_device_id sifive_l2_ids[] = {
> > -     { .compatible = "sifive,fu540-c000-ccache" },
> > -     { .compatible = "sifive,fu740-c000-ccache" },
> > -     { /* end of table */ },
> > -};
> > -
> >   static ATOMIC_NOTIFIER_HEAD(l2_err_chain);
> >
> >   int register_sifive_l2_error_notifier(struct notifier_block *nb)
> > @@ -192,36 +186,29 @@ static irqreturn_t l2_int_handler(int irq, void *device)
> >       return IRQ_HANDLED;
> >   }
> >
> > -static int __init sifive_l2_init(void)
> > +static int __init sifive_l2_probe(struct platform_device *pdev)
> >   {
> > -     struct device_node *np;
> > -     struct resource res;
> > -     int i, rc, intr_num;
> > -
> > -     np = of_find_matching_node(NULL, sifive_l2_ids);
> > -     if (!np)
> > -             return -ENODEV;
> > -
> > -     if (of_address_to_resource(np, 0, &res))
> > -             return -ENODEV;
> > -
> > -     l2_base = ioremap(res.start, resource_size(&res));
> > -     if (!l2_base)
> > -             return -ENOMEM;
> > -
> > -     intr_num = of_property_count_u32_elems(np, "interrupts");
> > -     if (!intr_num) {
> > -             pr_err("L2CACHE: no interrupts property\n");
> > -             return -ENODEV;
> > -     }
> > -
> > -     for (i = 0; i < intr_num; i++) {
> > -             g_irq[i] = irq_of_parse_and_map(np, i);
> > -             rc = request_irq(g_irq[i], l2_int_handler, 0, "l2_ecc", NULL);
> > -             if (rc) {
> > -                     pr_err("L2CACHE: Could not request IRQ %d\n", g_irq[i]);
> > -                     return rc;
> > -             }
> > +     struct device *dev = &pdev->dev;
> > +     int nirqs;
> > +     int ret;
> > +     int i;
> > +
> > +     l2_base = devm_platform_ioremap_resource(pdev, 0);
> > +     if (IS_ERR(l2_base))
> > +             return PTR_ERR(l2_base);
> > +
> > +     nirqs = platform_irq_count(pdev);
> > +     if (nirqs <= 0)
> > +             return dev_err_probe(dev, -ENODEV, "no interrupts\n");
>
> I wonder if zero irqs is an actual issue here?
>
> > +     for (i = 0; i < nirqs; i++) {
> > +             g_irq[i] = platform_get_irq(pdev, i);
>
> I wonder if we need to keep g_irq[] around now? Is it going to be useful
> in the future?
>
> > +             if (g_irq[i] < 0)
> > +                     return g_irq[i];
> > +
> > +             ret = devm_request_irq(dev, g_irq[i], l2_int_handler, 0, pdev->name, NULL);
> > +             if (ret)
> > +                     return dev_err_probe(dev, ret, "Could not request IRQ %d\n", g_irq[i]);
> >       }
> >
> >       l2_config_read();
> > @@ -234,4 +221,18 @@ static int __init sifive_l2_init(void)
> >   #endif
> >       return 0;
> >   }
> > -device_initcall(sifive_l2_init);
> > +
> > +static const struct of_device_id sifive_l2_match[] = {
> > +     { .compatible = "sifive,fu540-c000-ccache" },
> > +     { .compatible = "sifive,fu740-c000-ccache" },
> > +     { /* sentinel */ }
> > +};
> > +
> > +static struct platform_driver sifive_l2_driver = {
> > +     .driver = {
> > +             .name = "sifive_l2_cache",
> > +             .of_match_table = sifive_l2_match,
> > +             .suppress_bind_attrs = true,
> > +     },
> > +};
> > +builtin_platform_driver_probe(sifive_l2_driver, sifive_l2_probe);
>
>
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