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SubjectRe: [PATCH v3 2/9] soc: samsung: Convert exynos-chipid driver to use the regmap API
On Tue, 20 Aug 2019 at 21:24, Jon Hunter <jonathanh@nvidia.com> wrote:
>
>
> On 13/08/2019 16:08, Sylwester Nawrocki wrote:
> > Convert the driver to use regmap API in order to allow other
> > drivers, like ASV, to access the CHIPID registers.
> >
> > This patch adds definition of selected CHIPID register offsets
> > and register bit fields for Exynos5422 SoC.
> >
> > Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
> > ---
> > Changes since v2:
> > - s/_EXYNOS_ASV_H/__LINU_SOC_EXYNOS_ASV_H,
> > - removed __func__ from error log,
> > - removed unneeded <linux/of_address.h> header inclusion.
> >
> > Changes since v1 (RFC):
> > - new patch
> > ---
> > drivers/soc/samsung/exynos-chipid.c | 34 ++++++---------
> > include/linux/soc/samsung/exynos-chipid.h | 52 +++++++++++++++++++++++
> > 2 files changed, 65 insertions(+), 21 deletions(-)
> > create mode 100644 include/linux/soc/samsung/exynos-chipid.h
> >
> > diff --git a/drivers/soc/samsung/exynos-chipid.c b/drivers/soc/samsung/exynos-chipid.c
> > index bcf691f2b650..006a95feb618 100644
> > --- a/drivers/soc/samsung/exynos-chipid.c
> > +++ b/drivers/soc/samsung/exynos-chipid.c
> > @@ -9,16 +9,13 @@
> > */
> >
> > #include <linux/io.h>
> > +#include <linux/mfd/syscon.h>
> > #include <linux/of.h>
> > -#include <linux/of_address.h>
> > +#include <linux/regmap.h>
> > #include <linux/slab.h>
> > +#include <linux/soc/samsung/exynos-chipid.h>
> > #include <linux/sys_soc.h>
> >
> > -#define EXYNOS_SUBREV_MASK (0xF << 4)
> > -#define EXYNOS_MAINREV_MASK (0xF << 0)
> > -#define EXYNOS_REV_MASK (EXYNOS_SUBREV_MASK | EXYNOS_MAINREV_MASK)
> > -#define EXYNOS_MASK 0xFFFFF000
> > -
> > static const struct exynos_soc_id {
> > const char *name;
> > unsigned int id;
> > @@ -51,29 +48,24 @@ static const char * __init product_id_to_soc_id(unsigned int product_id)
> > int __init exynos_chipid_early_init(void)
> > {
> > struct soc_device_attribute *soc_dev_attr;
> > - void __iomem *exynos_chipid_base;
> > struct soc_device *soc_dev;
> > struct device_node *root;
> > - struct device_node *np;
> > + struct regmap *regmap;
> > u32 product_id;
> > u32 revision;
> > + int ret;
> >
> > - /* look up for chipid node */
> > - np = of_find_compatible_node(NULL, NULL, "samsung,exynos4210-chipid");
> > - if (!np)
> > - return -ENODEV;
> > -
> > - exynos_chipid_base = of_iomap(np, 0);
> > - of_node_put(np);
> > -
> > - if (!exynos_chipid_base) {
> > - pr_err("Failed to map SoC chipid\n");
> > - return -ENXIO;
> > + regmap = syscon_regmap_lookup_by_compatible("samsung,exynos4210-chipid");
> > + if (IS_ERR(regmap)) {
> > + pr_err("Failed to get CHIPID regmap\n");
> > + return PTR_ERR(regmap);
> > }
>
> Following this change, I am now seeing the above error on our Tegra
> boards where this driver is enabled. This is triggering a kernel
> warnings test we have to fail. Hence, I don't think that you can remove
> the compatible node test here, unless you have a better way to determine
> if this is a samsung device.

Right, this is really wrong... I missed that it is not a probe but
early init. And this init will be called on every board... Probably it
should be converted to a regular driver.

This is very old patchset, revived recently. I see that in v6 it was a
platform driver:
https://patchwork.kernel.org/patch/9134949/
Pankaj, apparently based on these comments, made it initcall... but why?

Another point is that Arnd complained there about exposing global
header and no change here - we still expose the global header, but not
with soc revisions but register internals... although it has its
purpose - other Exynos-specific drivers need to access through regmap.

Best regards,
Krzysztof

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