[PATCH v6 3/5] firmware: psci: Read and use vendor reset types

[Stephen Boyd]

Quoting Elliot Berman (2024-10-18 12:39:48)
> diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
> index 2328ca58bba6..60bc285622ce 100644
> --- a/drivers/firmware/psci/psci.c
> +++ b/drivers/firmware/psci/psci.c
> @@ -29,6 +29,8 @@
>  #include <asm/smp_plat.h>
>  #include <asm/suspend.h>
>
> +#define REBOOT_PREFIX "mode-"

Maybe move this near the function that uses it.

> +
>  /*
>   * While a 64-bit OS can make calls with SMC32 calling conventions, for some
>   * calls it is necessary to use SMC64 to pass or return 64-bit values.
> @@ -305,9 +315,29 @@ static int get_set_conduit_method(const struct device_node *np)
>         return 0;
>  }
>
> +static void psci_vendor_sys_reset2(unsigned long action, void *data)
> +{
> +       const char *cmd = data;
> +       unsigned long ret;
> +       size_t i;
> +
> +       for (i = 0; i < num_psci_reset_params; i++) {
> +               if (!strcmp(psci_reset_params[i].mode, cmd)) {
> +                       ret = invoke_psci_fn(PSCI_FN_NATIVE(1_1, SYSTEM_RESET2),
> +                                            psci_reset_params[i].reset_type,
> +                                            psci_reset_params[i].cookie, 0);
> +                       pr_err("failed to perform reset \"%s\": %ld\n",
> +                               cmd, (long)ret);

Do this intentionally return? Should it be some other function that's
__noreturn instead and a while (1) if the firmware returns back to the
kernel?

> +               }
> +       }
> +}
> +
>  static int psci_sys_reset(struct notifier_block *nb, unsigned long action,
>                           void *data)
>  {
> +       if (data && num_psci_reset_params)
> +               psci_vendor_sys_reset2(action, data);
> +
>         if ((reboot_mode == REBOOT_WARM || reboot_mode == REBOOT_SOFT) &&
>             psci_system_reset2_supported) {
>                 /*
> @@ -750,6 +780,68 @@ static const struct of_device_id psci_of_match[] __initconst = {
>         {},
>  };
>
> +static int __init psci_init_system_reset2_modes(void)
> +{
> +       const size_t len = strlen(REBOOT_PREFIX);
> +       struct psci_reset_param *param;
> +       struct device_node *psci_np __free(device_node) = NULL;
> +       struct device_node *np __free(device_node) = NULL;
> +       struct property *prop;
> +       size_t count = 0;
> +       u32 magic[2];
> +       int num;
> +
> +       if (!psci_system_reset2_supported)
> +               return 0;
> +
> +       psci_np = of_find_matching_node(NULL, psci_of_match);
> +       if (!psci_np)
> +               return 0;
> +
> +       np = of_find_node_by_name(psci_np, "reset-types");
> +       if (!np)
> +               return 0;
> +
> +       for_each_property_of_node(np, prop) {
> +               if (strncmp(prop->name, REBOOT_PREFIX, len))
> +                       continue;
> +               num = of_property_count_elems_of_size(np, prop->name, sizeof(magic[0]));

Use of_property_count_u32_elems()?

> +               if (num != 1 && num != 2)
> +                       continue;
> +
> +               count++;
> +       }
> +
> +       param = psci_reset_params = kcalloc(count, sizeof(*psci_reset_params), GFP_KERNEL);
> +       if (!psci_reset_params)
> +               return -ENOMEM;
> +
> +       for_each_property_of_node(np, prop) {
> +               if (strncmp(prop->name, REBOOT_PREFIX, len))
> +                       continue;
> +
> +               param->mode = kstrdup_const(prop->name + len, GFP_KERNEL);
> +               if (!param->mode)
> +                       continue;
> +
> +               num = of_property_read_variable_u32_array(np, prop->name, magic, 1, 2);

ARRAY_SIZE(magic)?

> +               if (num < 0) {

Should this be less than 1?

> +                       pr_warn("Failed to parse vendor reboot mode %s\n", param->mode);
> +                       kfree_const(param->mode);
> +                       continue;
> +               }
> +
> +               /* Force reset type to be in vendor space */
> +               param->reset_type = PSCI_1_1_RESET_TYPE_VENDOR_START | magic[0];
> +               param->cookie = num == 2 ? magic[1] : 0;

ARRAY_SIZE(magic)?

> +               param++;
> +               num_psci_reset_params++;
> +       }
> +
> +       return 0;