On 2/26/19 9:31 PM, Simon Goldschmidt wrote:
> This adds code to take peripherals out of reset based on an environment
> variable. This is in preparation for removing the code that does this from
> SPL.
>
> However, some drivers even in current Linux cannot handle peripheral reset,
> so until this works, we need a compatibility workaround.
>
> This workaround is implemented in the 'assert' and 'remove' callbacks of
> this reset driver: the 'assert' callback does not disable peripherals that
> were already taken out of reset, while the 'remove' callback, which is
> called on OS_PREPARE, deasserts all peripheral resets if the environment
> variable "socfpga_legacy_reset_compat" is set to 1, which is what the gen5
> SPL did up to now.
>
> This is in preparation to clean up the SPL and implementing proper reset
> handling for U-Boot.
>
> Signed-off-by: Simon Goldschmidt <simon.k.r.goldschm...@gmail.com>
> ---
>
> Changes in v3:
> - fix falcon mode in SPL should work, too
> - change env var name "socfpga_permodrst_ungate" to
> "socfpga_legacy_reset_compat"
> - in compat mode, don't reset peripherals once they are enabled
>
> Changes in v2:
> - moved from Kernel option "OLD_SOCFPGA_KERNEL_COMPAT" to environment
> variable "socfpga_permodrst_ungate"
>
> drivers/reset/reset-socfpga.c | 44 +++++++++++++++++++++++++++++++++++
> 1 file changed, 44 insertions(+)
>
> diff --git a/drivers/reset/reset-socfpga.c b/drivers/reset/reset-socfpga.c
> index b2acfcd2ec..39d0b9e8f2 100644
> --- a/drivers/reset/reset-socfpga.c
> +++ b/drivers/reset/reset-socfpga.c
> @@ -27,6 +27,36 @@ struct socfpga_reset_data {
> void __iomem *membase;
> };
>
> +/*
> + * For compatibility with Kernels that don't support peripheral reset, this
> + * driver can keep the old behaviour of not asserting peripheral reset before
> + * starting the OS and deasserting all peripheral resets (enabling all
> + * peripherals).
> + *
> + * For that, the reset driver checks the environment variable
> + * "socfpga_legacy_reset_compat". If this variable is '1', perihperals are
> not
> + * reset again once taken out of reset and all peripherals in 'permodrst' are
> + * taken out of reset before booting into the OS.
> + * Note that this should be required for gen5 systems only that are running
> + * Linux kernels without proper peripheral reset support for all drivers
> used.
> + */
> +static bool socfpga_reset_keep_enabled(void)
> +{
> +#if !defined(CONFIG_SPL_BUILD) || CONFIG_IS_ENABLED(ENV_SUPPORT)
> + const char *env_str;
> + long val;
> +
> + env_str = env_get("socfpga_legacy_reset_compat");
> + if (env_str) {
> + val = simple_strtol(env_str, NULL, 0);
> + if (val == 1)
> + return true;
> + }
> +#endif
> +
> + return false;
> +}
> +
> static int socfpga_reset_assert(struct reset_ctl *reset_ctl)
> {
> struct socfpga_reset_data *data = dev_get_priv(reset_ctl->dev);
> @@ -89,6 +119,18 @@ static int socfpga_reset_probe(struct udevice *dev)
> return 0;
> }
>
> +static int socfpga_reset_remove(struct udevice *dev)
> +{
> + struct socfpga_reset_data *data = dev_get_priv(dev);
> +
> + if (socfpga_reset_keep_enabled()) {
> + puts("Deasserting all peripheral resets\n");
> + writel(0, data->membase + 4);
Isn't permodreset at +0x14 ?
> + }
> +
> + return 0;
> +}
> +
> static const struct udevice_id socfpga_reset_match[] = {
> { .compatible = "altr,rst-mgr" },
> { /* sentinel */ },
> @@ -101,4 +143,6 @@ U_BOOT_DRIVER(socfpga_reset) = {
> .probe = socfpga_reset_probe,
> .priv_auto_alloc_size = sizeof(struct socfpga_reset_data),
> .ops = &socfpga_reset_ops,
> + .remove = socfpga_reset_remove,
> + .flags = DM_FLAG_OS_PREPARE,
> };
>
--
Best regards,
Marek Vasut
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