[U-Boot] [PATCH 03/14] env: Pass additional parameters to the env lookup function

Andre Przywara
2017-12-05T10:09:04Z

Hi Maxime,

On 28/11/17 10:24, Maxime Ripard wrote:
> In preparation for the multiple environment support, let's introduce two
> new parameters to the environment driver lookup function: the priority and
> operation.
>
> The operation parameter is meant to identify, obviously, the operation you
> might want to perform on the environment.

I wonder if this is a bit too generic. Wouldn't a simple:
bool is_save_op (or some more clever name)
be sufficient? At least this is actually all we need, if I understand
the code correctly.
But it's up to you, I can see advantages for both approaches.

> The priority is a number passed to identify the environment priority you
> want to retrieve. The lowest priority parameter (0) will be the primary
> source.
>
> Combining the two parameters allow you to support multiple environments
> through different priorities, and to change those priorities between read
> and writes operations.
>
> This is especially useful to implement migration mechanisms where you want
> to always use the same environment first, be it to read or write, while the
> common case is more likely to use the same environment it has read from to
> write it to.
>
> Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
> ---
> env/env.c | 122 +++++++++++++++++++++++++------------------
> include/environment.h | 7 ++-
> 2 files changed, 80 insertions(+), 49 deletions(-)
>
> diff --git a/env/env.c b/env/env.c
> index 97ada5b5a6fd..673bfa6ba41b 100644
> --- a/env/env.c
> +++ b/env/env.c
> @@ -26,8 +26,11 @@ static struct env_driver *_env_driver_lookup(enum env_location loc)
> return NULL;
> }
>
> -static enum env_location env_get_location(void)
> +static enum env_location env_get_location(enum env_operation op, int prio)
> {
> + if (prio >= 1)
> + return ENVL_UNKNOWN;
> +
> if IS_ENABLED(CONFIG_ENV_IS_IN_EEPROM)
> return ENVL_EEPROM;
> else if IS_ENABLED(CONFIG_ENV_IS_IN_FAT)
> @@ -52,11 +55,14 @@ static enum env_location env_get_location(void)
> return ENVL_UNKNOWN;
> }
>
> -static struct env_driver *env_driver_lookup(void)
> +static struct env_driver *env_driver_lookup(enum env_operation op, int prio)
> {
> - enum env_location loc = env_get_location();
> + enum env_location loc = env_get_location(op, prio);
> struct env_driver *drv;
>
> + if (loc == ENVL_UNKNOWN)
> + return NULL;
> +
> drv = _env_driver_lookup(loc);
> if (!drv) {
> debug("%s: No environment driver for location %d\n", __func__,
> @@ -69,83 +75,101 @@ static struct env_driver *env_driver_lookup(void)
>
> int env_get_char(int index)
> {
> - struct env_driver *drv = env_driver_lookup();
> - int ret;
> + struct env_driver *drv;
> + int prio;
>
> if (gd->env_valid == ENV_INVALID)
> return default_environment[index];
> - if (!drv)
> - return -ENODEV;
> - if (!drv->get_char)
> - return *(uchar *)(gd->env_addr + index);

Did you deliberately remove this fallback from the new code below?

> - ret = drv->get_char(index);
> - if (ret < 0) {
> - debug("%s: Environment failed to load (err=%d)\n",
> - __func__, ret);
> +
> + for (prio = 0; (drv = env_driver_lookup(ENVO_GET_CHAR, prio)); prio++) {
> + int ret;
> +
> + if (!drv->get_char)
> + continue;
> +
> + ret = drv->get_char(index);
> + if (!ret)
> + return 0;
> +
> + debug("%s: Environment %s failed to load (err=%d)\n", __func__,
> + drv->name, ret);
> }
>
> - return ret;
> + return -ENODEV;
> }
>
> int env_load(void)
> {
> - struct env_driver *drv = env_driver_lookup();
> - int ret = 0;
> + struct env_driver *drv;
> + int prio;
>
> - if (!drv)
> - return -ENODEV;
> - if (!drv->load)
> - return 0;
> - ret = drv->load();
> - if (ret) {
> - debug("%s: Environment failed to load (err=%d)\n", __func__,
> - ret);
> - return ret;
> + for (prio = 0; (drv = env_driver_lookup(ENVO_LOAD, prio)); prio++) {
> + int ret;
> +
> + if (!drv->load)
> + continue;

Is this change to the algorithm acceptable? Formerly we returned 0 on
finding a drv->load pointer to be NULL, now it's -ENODEV, plus we try to
find other sources first.
Or is that solved later somehow with the env_has_init bitmap?

> +
> + ret = drv->load();
> + if (!ret)
> + return 0;
> +
> + debug("%s: Environment %s failed to load (err=%d)\n", __func__,
> + drv->name, ret);
> }
>
> - return 0;
> + return -ENODEV;
> }
>
> int env_save(void)
> {
> - struct env_driver *drv = env_driver_lookup();
> - int ret;
> + struct env_driver *drv;
> + int prio;
>
> - if (!drv)
> - return -ENODEV;
> - if (!drv->save)
> - return -ENOSYS;
> -
> - printf("Saving Environment to %s...\n", drv->name);
> - ret = drv->save();
> - if (ret) {
> - debug("%s: Environment failed to save (err=%d)\n", __func__,
> - ret);
> - return ret;
> + for (prio = 0; (drv = env_driver_lookup(ENVO_SAVE, prio)); prio++) {
> + int ret;
> +
> + if (!drv->save)
> + continue;

Same as for env_load().

Cheers,
Andre

> +
> + printf("Saving Environment to %s...\n", drv->name);
> + ret = drv->save();
> + if (!ret)
> + return 0;
> +
> + debug("%s: Environment %s failed to save (err=%d)\n", __func__,
> + drv->name, ret);
> }
>
> - return 0;
> + return -ENODEV;
> }
>
> int env_init(void)
> {
> - struct env_driver *drv = env_driver_lookup();
> + struct env_driver *drv;
> int ret = -ENOENT;
> + int prio;
> +
> + for (prio = 0; (drv = env_driver_lookup(ENVO_INIT, prio)); prio++) {
> + if (!drv->init)
> + continue;
>
> - if (!drv)
> - return -ENODEV;
> - if (drv->init)
> ret = drv->init();
> + if (!ret)
> + return 0;
> +
> + debug("%s: Environment %s failed to init (err=%d)\n", __func__,
> + drv->name, ret);
> + }
> +
> + if (!prio)
> + return -ENODEV;
> +
> if (ret == -ENOENT) {
> gd->env_addr = (ulong)&default_environment[0];
> gd->env_valid = ENV_VALID;
>
> return 0;
> - } else if (ret) {
> - debug("%s: Environment failed to init (err=%d)\n", __func__,
> - ret);
> - return ret;
> }
>
> - return 0;
> + return ret;
> }
> diff --git a/include/environment.h b/include/environment.h
> index 226e3ef2d23a..7fa8b98cc0db 100644
> --- a/include/environment.h
> +++ b/include/environment.h
> @@ -215,6 +215,13 @@ enum env_location {
> ENVL_UNKNOWN,
> };
>
> +enum env_operation {
> + ENVO_GET_CHAR,
> + ENVO_INIT,
> + ENVO_LOAD,
> + ENVO_SAVE,
> +};
> +
> struct env_driver {
> const char *name;
> enum env_location location;
>