[PATCH v2 3/5] lib: utils/i2c: Add simple FDT based I2C framework

[Nikita Shubin]

Hello Alexandre!

On Tue, 19 Oct 2021 14:05:58 +0200
Alexandre Ghiti <alexandre.ghiti at canonical.com> wrote:

> On Fri, Oct 15, 2021 at 3:20 PM Nikita Shubin
> <nikita.shubin at maquefel.me> wrote:
> >
> > From: Nikita Shubin <n.shubin at yadro.com>
> >
> > FDT based I2C framework on the top of I2C library.
> >
> > The drivers are probed on demand by fdt_i2c_adapter_get
> > function.
> >
> > Signed-off-by: Nikita Shubin <n.shubin at yadro.com>
> > ---
> >  include/sbi_utils/i2c/fdt_i2c.h |  26 ++++++++
> >  lib/utils/i2c/fdt_i2c.c         | 108
> > ++++++++++++++++++++++++++++++++ lib/utils/i2c/objects.mk        |
> >  1 + 3 files changed, 135 insertions(+)
> >  create mode 100644 include/sbi_utils/i2c/fdt_i2c.h
> >  create mode 100644 lib/utils/i2c/fdt_i2c.c
> >
> > diff --git a/include/sbi_utils/i2c/fdt_i2c.h
> > b/include/sbi_utils/i2c/fdt_i2c.h new file mode 100644
> > index 0000000..1f41a0f
> > --- /dev/null
> > +++ b/include/sbi_utils/i2c/fdt_i2c.h
> > @@ -0,0 +1,26 @@
> > +/*
> > + * SPDX-License-Identifier: BSD-2-Clause
> > + *
> > + * Copyright (c) 2021 YADRO
> > + *
> > + * Authors:
> > + *   Nikita Shubin <nshubin at yadro.com>
> > + */
> > +
> > +#ifndef __FDT_I2C_H__
> > +#define __FDT_I2C_H__
> > +
> > +#include <sbi_utils/i2c/i2c.h>
> > +
> > +/** FDT based I2C adapter driver */
> > +struct fdt_i2c_adapter {
> > +       const struct fdt_match *match_table;
> > +       int (*init)(void *fdt, int nodeoff,
> > +                   const struct fdt_match *match);
> > +};
> > +
> > +/** Get I2C adapter identified by nodeoff */
> > +int fdt_i2c_adapter_get(void *fdt, int nodeoff,
> > +                       struct i2c_adapter **out_adapter);
> > +
> > +#endif
> > diff --git a/lib/utils/i2c/fdt_i2c.c b/lib/utils/i2c/fdt_i2c.c
> > new file mode 100644
> > index 0000000..fce6d73
> > --- /dev/null
> > +++ b/lib/utils/i2c/fdt_i2c.c
> > @@ -0,0 +1,108 @@
> > +/*
> > + * SPDX-License-Identifier: BSD-2-Clause
> > + *
> > + * Copyright (c) 2021 YADRO
> > + *
> > + * Authors:
> > + *   Nikita Shubin <nshubin at yadro.com>
> > + *
> > + * derivate: lib/utils/gpio/fdt_gpio.c
> > + * Authors:
> > + *   Anup Patel <anup.patel at wdc.com>
> > + */
> > +
> > +#include <libfdt.h>
> > +#include <sbi/sbi_error.h>
> > +#include <sbi_utils/fdt/fdt_helper.h>
> > +#include <sbi_utils/i2c/fdt_i2c.h>
> > +
> > +#include <sbi/sbi_console.h>
> > +
> > +static struct fdt_i2c_adapter *i2c_adapter_drivers[] = {
> > +};
> > +
> > +static struct fdt_i2c_adapter
> > +       *fdt_i2c_adapter_driver(struct i2c_adapter *adapter)
> > +{
> > +       int pos;
> > +
> > +       if (!adapter)
> > +               return NULL;
> > +
> > +       for (pos = 0; pos < array_size(i2c_adapter_drivers); pos++)
> > {
> > +               if (adapter->driver == i2c_adapter_drivers[pos])
> > +                       return i2c_adapter_drivers[pos];
> > +       }
> > +
> > +       return NULL;
> > +}  
> 
> I don't see the point of this function since it simply returns
> adapter->driver right?

It looks like you are right. This can be ommited as well as 
fdt_i2c_adapter_driver check in fdt_i2c_adapter_get.

> 
> > +
> > +static int fdt_i2c_adapter_init(void *fdt, int nodeoff)
> > +{
> > +       int pos, rc;
> > +       struct fdt_i2c_adapter *drv;
> > +       const struct fdt_match *match;
> > +
> > +       /* Try all I2C drivers one-by-one */
> > +       for (pos = 0; pos < array_size(i2c_adapter_drivers); pos++)
> > {
> > +               drv = i2c_adapter_drivers[pos];
> > +               match = fdt_match_node(fdt, nodeoff,
> > drv->match_table);
> > +               if (match && drv->init) {
> > +                       rc = drv->init(fdt, nodeoff, match);
> > +                       if (rc == SBI_ENODEV)
> > +                               continue;
> > +                       if (rc)
> > +                               return rc;
> > +                       return 0;
> > +               }
> > +       }
> > +
> > +       return SBI_ENOSYS;
> > +}
> > +
> > +static int fdt_i2c_adapter_find(void *fdt, int nodeoff,
> > +                               struct i2c_adapter **out_adapter)
> > +{
> > +       int rc;
> > +       struct i2c_adapter *adapter = i2c_adapter_find(nodeoff);
> > +
> > +       if (!adapter) {
> > +               /* I2C adapter not found so initialize matching
> > driver */
> > +               rc = fdt_i2c_adapter_init(fdt, nodeoff);
> > +               if (rc)
> > +                       return rc;
> > +
> > +               /* Try to find I2C adapter again */
> > +               adapter = i2c_adapter_find(nodeoff);
> > +               if (!adapter)
> > +                       return SBI_ENOSYS;
> > +       }
> > +
> > +       if (out_adapter)
> > +               *out_adapter = adapter;
> > +
> > +       return 0;
> > +}
> > +
> > +int fdt_i2c_adapter_get(void *fdt, int nodeoff,
> > +                       struct i2c_adapter **out_adapter)
> > +{
> > +       int rc;
> > +       struct i2c_adapter *adapter;
> > +       struct fdt_i2c_adapter *drv;
> > +
> > +       if (!fdt || (nodeoff < 0) || !out_adapter)
> > +               return SBI_EINVAL;
> > +
> > +       rc = fdt_i2c_adapter_find(fdt, nodeoff, &adapter);
> > +       if (rc)
> > +               return rc;
> > +
> > +       drv = fdt_i2c_adapter_driver(adapter);
> > +       if (!drv)
> > +               return SBI_ENOSYS;
> > +
> > +       *out_adapter = adapter;
> > +
> > +       return 0;
> > +}
> > diff --git a/lib/utils/i2c/objects.mk b/lib/utils/i2c/objects.mk
> > index 16a70da..06baa65 100644
> > --- a/lib/utils/i2c/objects.mk
> > +++ b/lib/utils/i2c/objects.mk
> > @@ -8,3 +8,4 @@
> >  #
> >
> >  libsbiutils-objs-y += i2c/i2c.o
> > +libsbiutils-objs-y += i2c/fdt_i2c.o
> > --
> > 2.31.1
> >
> >
> > --
> > opensbi mailing list
> > opensbi at lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/opensbi