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

[Conor Dooley <conor@xxxxxxxxxx>]

On Wed, Oct 05, 2022 at 03:55:17PM +0200, Emil Renner Berthing wrote:
> On Wed, 5 Oct 2022 at 15:48, Ben Dooks <ben.dooks@xxxxxxxxxxxxxxx> wrote:
> >
> > On 05/10/2022 14:44, Emil Renner Berthing wrote:
> > > 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
> >
> > Are you replying to your own patch that does the conversion to
> > platform driver and then saying that it could actually cause
> > issues?
> 
> Yes, I can see it seems odd, but this patch lived for a while in the
> kernel repo for the JH7100 until I rebased on 6.0-rc1 and realized the
> above.
> Hal Feng must have based his patches on a version of the code before
> that when preparing this series.
> 
> > I'm all for dropping this for the moment and keeping the old
> > early init for the ccache.
> 
> Cool.

FWIW, if converting to a platform driver will inhibit using the driver
for doing non-coherent stuff I would like to NAK the patch :)

> 
> /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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> > >
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> > >
> >
> > --
> > Ben Dooks                               http://www.codethink.co.uk/
> > Senior Engineer                         Codethink - Providing Genius
> >
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> >