[PATCH 2/3] firmware: psci: Add support for dt-supplied SYSTEM_RESET2 type

From: Elliot Berman
Date: Fri Feb 21 2020 - 18:28:24 EST


Some implementors of PSCI may relax the requirements of the PSCI
architectural warm reset. In order to comply with PSCI specification, a
different reset_type value must be used. The alternate PSCI
SYSTEM_RESET2 may be used in all warm/soft reboot scenarios, replacing
the architectural warm reset.

Signed-off-by: Elliot Berman <eberman@xxxxxxxxxxxxxx>
---
drivers/firmware/psci/psci.c | 21 +++++++++++++++++----
include/linux/psci.h | 1 +
include/uapi/linux/psci.h | 2 ++
3 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
index 2937d44..75e6a38 100644
--- a/drivers/firmware/psci/psci.c
+++ b/drivers/firmware/psci/psci.c
@@ -55,6 +55,7 @@ bool psci_tos_resident_on(int cpu)
struct psci_operations psci_ops = {
.conduit = SMCCC_CONDUIT_NONE,
.smccc_version = SMCCC_VERSION_1_0,
+ .sys_reset2_reset_type = PSCI_1_1_SYSTEM_RESET2_SYSTEM_WARM_RESET,
};

enum arm_smccc_conduit arm_smccc_1_1_get_conduit(void)
@@ -272,11 +273,10 @@ static void psci_sys_reset(enum reboot_mode reboot_mode, const char *cmd)
if ((reboot_mode == REBOOT_WARM || reboot_mode == REBOOT_SOFT) &&
psci_system_reset2_supported) {
/*
- * reset_type[31] = 0 (architectural)
- * reset_type[30:0] = 0 (SYSTEM_WARM_RESET)
* cookie = 0 (ignored by the implementation)
*/
- invoke_psci_fn(PSCI_FN_NATIVE(1_1, SYSTEM_RESET2), 0, 0, 0);
+ invoke_psci_fn(PSCI_FN_NATIVE(1_1, SYSTEM_RESET2),
+ psci_ops.sys_reset2_reset_type, 0, 0);
} else {
invoke_psci_fn(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0);
}
@@ -493,6 +493,7 @@ typedef int (*psci_initcall_t)(const struct device_node *);
static int __init psci_0_2_init(struct device_node *np)
{
int err;
+ u32 param;

err = get_set_conduit_method(np);
if (err)
@@ -505,7 +506,19 @@ static int __init psci_0_2_init(struct device_node *np)
* can be carried out according to the specific version reported
* by firmware
*/
- return psci_probe();
+ err = psci_probe();
+ if (err)
+ return err;
+
+ if (psci_system_reset2_supported &&
+ !of_property_read_u32(np, "arm,psci-sys-reset2-type", &param)) {
+ if ((s32)param > 0)
+ pr_warn("%08x is an invalid architectural reset type.\n",
+ param);
+ psci_ops.sys_reset2_reset_type = param;
+ }
+
+ return 0;
}

/*
diff --git a/include/linux/psci.h b/include/linux/psci.h
index a67712b..1959a80 100644
--- a/include/linux/psci.h
+++ b/include/linux/psci.h
@@ -37,6 +37,7 @@ struct psci_operations {
int (*migrate_info_type)(void);
enum arm_smccc_conduit conduit;
enum smccc_version smccc_version;
+ u32 sys_reset2_reset_type;
};

extern struct psci_operations psci_ops;
diff --git a/include/uapi/linux/psci.h b/include/uapi/linux/psci.h
index 2fcad1d..d786ec8 100644
--- a/include/uapi/linux/psci.h
+++ b/include/uapi/linux/psci.h
@@ -55,6 +55,8 @@
#define PSCI_1_0_FN64_SYSTEM_SUSPEND PSCI_0_2_FN64(14)
#define PSCI_1_1_FN64_SYSTEM_RESET2 PSCI_0_2_FN64(18)

+#define PSCI_1_1_SYSTEM_RESET2_SYSTEM_WARM_RESET 0
+
/* 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
--
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