Re: [PATCH 5/7] misc: implement PSCI system reset driver

[Sascha Hauer]

On Wed, Nov 06, 2019 at 08:10:32AM +0100, Ahmad Fatoum wrote:
> In cases where firmware provides PSCI >0.1, it may be prudent to use it as
> backend for reset and poweroff. This driver accomplishes this.
> 
> Signed-off-by: Ahmad Fatoum 
> ---
>  drivers/misc/Kconfig |  5 +++
>  drivers/misc/Makefile|  1 +
>  drivers/misc/psci-sysreset.c | 62 
>  3 files changed, 68 insertions(+)
>  create mode 100644 drivers/misc/psci-sysreset.c
> 
> diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
> index 0f736f8bded3..0412fcf02aa3 100644
> --- a/drivers/misc/Kconfig
> +++ b/drivers/misc/Kconfig
> @@ -35,4 +35,9 @@ config UBOOTVAR
> While it can be used standalone, it is best when coupled
> with corresponding filesystem driver.
>  
> +config PSCI_SYSRESET
> + bool "PSCI system reset driver"
> + select ARM_PSCI_CLIENT
> + depends on CPU_32v7 || CPU_64v8

I would rather prefer to be ARM_PSCI_CLIENT a user visible option.

> +static int __init psci_sysreset_init(void)
> +{
> + int version;
> + int ret;
> +
> + version = psci_get_version();
> + if (version < 0)
> + return version;

This prints a warning for everyone who has this code enabled but doesn't
have psci support. Also you enforce that the psci client driver has to
be registered already.
I think this code should rather be merged into the psci client driver,
there's no need for an additional initcall.

Sascha

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[PATCH 5/7] misc: implement PSCI system reset driver

[Ahmad Fatoum]

In cases where firmware provides PSCI >0.1, it may be prudent to use it as
backend for reset and poweroff. This driver accomplishes this.

Signed-off-by: Ahmad Fatoum 
---
 drivers/misc/Kconfig |  5 +++
 drivers/misc/Makefile|  1 +
 drivers/misc/psci-sysreset.c | 62 
 3 files changed, 68 insertions(+)
 create mode 100644 drivers/misc/psci-sysreset.c

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 0f736f8bded3..0412fcf02aa3 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -35,4 +35,9 @@ config UBOOTVAR
  While it can be used standalone, it is best when coupled
  with corresponding filesystem driver.
 
+config PSCI_SYSRESET
+   bool "PSCI system reset driver"
+   select ARM_PSCI_CLIENT
+   depends on CPU_32v7 || CPU_64v8
+
 endmenu
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index bc1c01ea4d67..0ad158b16d1b 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -7,3 +7,4 @@ obj-$(CONFIG_SRAM)  += sram.o
 obj-$(CONFIG_STATE_DRV)+= state.o
 obj-$(CONFIG_DEV_MEM)  += mem.o
 obj-$(CONFIG_UBOOTVAR) += ubootvar.o
+obj-$(CONFIG_PSCI_SYSRESET)+= psci-sysreset.o
diff --git a/drivers/misc/psci-sysreset.c b/drivers/misc/psci-sysreset.c
new file mode 100644
index ..d05cbc76f259
--- /dev/null
+++ b/drivers/misc/psci-sysreset.c
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2017 Masahiro Yamada 
+ * Copyright (C) 2019 Ahmad Fatoum, Pengutronix
+ */
+
+#define pr_fmt(fmt) "psci-sysreset: " fmt
+
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+
+static struct restart_handler restart;
+
+static void __noreturn psci_invoke_noreturn(int function)
+{
+   int ret;
+
+   ret = psci_invoke(function, 0, 0, 0, NULL);
+
+   pr_err("psci command failed: %s\n", strerror(-ret));
+   hang();
+}
+
+static void __noreturn psci_poweroff(struct poweroff_handler *handler)
+{
+   psci_invoke_noreturn(ARM_PSCI_0_2_FN_SYSTEM_OFF);
+}
+
+static void __noreturn psci_restart(struct restart_handler *rst)
+{
+   psci_invoke_noreturn(ARM_PSCI_0_2_FN_SYSTEM_RESET);
+}
+
+static int __init psci_sysreset_init(void)
+{
+   int version;
+   int ret;
+
+   version = psci_get_version();
+   if (version < 0)
+   return version;
+
+   if (version < ARM_PSCI_VER(0,2)) {
+   pr_debug("Incompatible PSCI version: not registering reset 
handler\n");
+   return 0;
+   }
+
+   ret = poweroff_handler_register_fn(psci_poweroff);
+   if (ret)
+   return ret;
+
+   restart.name = "psci";
+   restart.restart = psci_restart;
+   restart.priority = 400;
+
+   return restart_handler_register();
+}
+device_initcall(psci_sysreset_init);
-- 
2.24.0.rc1


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