[PATCH 2/4] lib: utils/gpio: Add simple FDT based I2C framework

[Xiang W]

在 2021-09-24星期五的 14:33 +0300，Nikita Shubin写道：
> 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         | 107
> ++++++++++++++++++++++++++++++++
>  lib/utils/i2c/objects.mk        |   1 +
>  3 files changed, 134 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..27e28a4
> --- /dev/null
> +++ b/lib/utils/i2c/fdt_i2c.c
> @@ -0,0 +1,107 @@
> +/*
> + * 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;
> +}
> +
> +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 */
Reinitializing the I2C adapter may affect other adapters that have
already been initialized. So I suggest to add a static variable,
through this control the initial operation is executed once.

Regards,
Xiang W
> +               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
> 
>