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SubjectRe: [PATCH] drivers: firmware: psci: add support for warm reset
On Mon, Apr 01, 2019 at 09:14:43PM +0300, Aaro Koskinen wrote:
> From: Aaro Koskinen <aaro.koskinen@nokia.com>
>
> Add support for warm reset using SYSTEM_RESET2 introduced in PSCI
> 1.1 specification.

For reference, how do you intend to use this?

>
> Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com>
> ---
> drivers/firmware/psci.c | 25 +++++++++++++++++++++++++
> include/uapi/linux/psci.h | 3 +++
> 2 files changed, 28 insertions(+)
>
> diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
> index c80ec1d03274..1d95b5f6d403 100644
> --- a/drivers/firmware/psci.c
> +++ b/drivers/firmware/psci.c
> @@ -73,6 +73,7 @@ enum psci_function {
> PSCI_FN_CPU_ON,
> PSCI_FN_CPU_OFF,
> PSCI_FN_MIGRATE,
> + PSCI_FN_SYSTEM_RESET2,
> PSCI_FN_MAX,
> };
>
> @@ -256,6 +257,14 @@ static void psci_sys_reset(enum reboot_mode reboot_mode, const char *cmd)
> invoke_psci_fn(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0);
> }
>
> +static void psci_sys_reset2(enum reboot_mode reboot_mode, const char *cmd)
> +{
> + if (reboot_mode == REBOOT_WARM)
> + invoke_psci_fn(psci_function_id[PSCI_FN_SYSTEM_RESET2], 0, 0, 0);
> + else
> + psci_sys_reset(reboot_mode, cmd);
> +}

What happens when RESET2 isn't available, but the user requests s REBOOT_WARM
reset? It looks like we'd invoke a bogus SMC.

Could we please add a preprocessor definition for SYSTEM_RESET_WARM so that
it's clear that we're passing a parameter here?

> +
> static void psci_sys_poweroff(void)
> {
> invoke_psci_fn(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0);
> @@ -564,6 +573,20 @@ static void __init psci_0_2_set_functions(void)
> pm_power_off = psci_sys_poweroff;
> }
>
> +static void __init psci_1_1_set_functions(void)
> +{
> + int sys_reset2;
> + int feature;
> +
> + sys_reset2 = PSCI_FN_NATIVE(1_1, SYSTEM_RESET2);
> + feature = psci_features(sys_reset2);
> +
> + if (feature != PSCI_RET_NOT_SUPPORTED) {
> + psci_function_id[PSCI_FN_SYSTEM_RESET2] = sys_reset2;
> + arm_pm_restart = psci_sys_reset2;
> + }
> +}
> +
> /*
> * Probe function for PSCI firmware versions >= 0.2
> */
> @@ -588,6 +611,8 @@ static int __init psci_probe(void)
> psci_init_smccc();
> psci_init_cpu_suspend();
> psci_init_system_suspend();
> + if (PSCI_VERSION_MINOR(ver) >= 1)
> + psci_1_1_set_functions();
> }

If we're going to add more things to this chain, can we please refactor this as:

if (ver < PSCI_VERSION(1, 0))
return;

/* PSCI 1.0 setup here */

if (ver < PSCI_VERSION(1,1))
return;

/* PSCI 1.1 setup here */

... as that saves on indentation and is easier to extend in future.

Thanks,
Mark

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