drivers: firmware: psci: add support for warm reset
diff mbox series

Message ID 20190401181443.6459-1-aaro.koskinen@iki.fi
State Superseded
Headers show
Series
  • drivers: firmware: psci: add support for warm reset
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Commit Message

Aaro Koskinen April 1, 2019, 6:14 p.m. UTC
From: Aaro Koskinen <aaro.koskinen@nokia.com>

Add support for warm reset using SYSTEM_RESET2 introduced in PSCI
1.1 specification.

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(+)

Comments

Mark Rutland April 3, 2019, 3:33 a.m. UTC | #1
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
Aaro Koskinen April 3, 2019, 6:12 p.m. UTC | #2
Hi,

On Wed, Apr 03, 2019 at 04:33:15AM +0100, Mark Rutland wrote:
> 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?

The reboot mode is set using the kernel command line. One use case for warm
reset is pstore/ramoops.

> > @@ -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.

This function is only called through arm_pm_restart. If the feature is
not available, then arm_pm_restart points to the default psci_sys_reset.

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

OK, will add.

> >  /*
> >   * 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.

OK, makes sense, I will do that.

Thanks,

A.

Patch
diff mbox series

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);
+}
+
 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();
 	}
 
 	return 0;
diff --git a/include/uapi/linux/psci.h b/include/uapi/linux/psci.h
index b3bcabe380da..f36e616c3b3f 100644
--- a/include/uapi/linux/psci.h
+++ b/include/uapi/linux/psci.h
@@ -52,6 +52,9 @@ 
 
 #define PSCI_1_0_FN64_SYSTEM_SUSPEND		PSCI_0_2_FN64(14)
 
+#define PSCI_1_1_FN_SYSTEM_RESET2		PSCI_0_2_FN(18)
+#define PSCI_1_1_FN64_SYSTEM_RESET2		PSCI_0_2_FN64(18)
+
 /* PSCI v0.2 power state encoding for CPU_SUSPEND function */
 #define PSCI_0_2_POWER_STATE_ID_MASK		0xffff
 #define PSCI_0_2_POWER_STATE_ID_SHIFT		0