diff options
| -rw-r--r-- | drivers/firmware/arm_scmi/Kconfig | 14 | ||||
| -rw-r--r-- | drivers/firmware/arm_scmi/smc.c | 56 |
2 files changed, 64 insertions, 6 deletions
diff --git a/drivers/firmware/arm_scmi/Kconfig b/drivers/firmware/arm_scmi/Kconfig index 638ecec89ff1..d429326433d1 100644 --- a/drivers/firmware/arm_scmi/Kconfig +++ b/drivers/firmware/arm_scmi/Kconfig @@ -78,6 +78,20 @@ config ARM_SCMI_TRANSPORT_SMC If you want the ARM SCMI PROTOCOL stack to include support for a transport based on SMC, answer Y. +config ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE + bool "Enable atomic mode support for SCMI SMC transport" + depends on ARM_SCMI_TRANSPORT_SMC + help + Enable support of atomic operation for SCMI SMC based transport. + + If you want the SCMI SMC based transport to operate in atomic + mode, avoiding any kind of sleeping behaviour for selected + transactions on the TX path, answer Y. + Enabling atomic mode operations allows any SCMI driver using this + transport to optionally ask for atomic SCMI transactions and operate + in atomic context too, at the price of using a number of busy-waiting + primitives all over instead. If unsure say N. + config ARM_SCMI_TRANSPORT_VIRTIO bool "SCMI transport based on VirtIO" depends on VIRTIO=y || VIRTIO=ARM_SCMI_PROTOCOL diff --git a/drivers/firmware/arm_scmi/smc.c b/drivers/firmware/arm_scmi/smc.c index df0defd9f8bb..6c7871a40611 100644 --- a/drivers/firmware/arm_scmi/smc.c +++ b/drivers/firmware/arm_scmi/smc.c @@ -7,6 +7,7 @@ */ #include <linux/arm-smccc.h> +#include <linux/atomic.h> #include <linux/device.h> #include <linux/err.h> #include <linux/interrupt.h> @@ -14,6 +15,7 @@ #include <linux/of.h> #include <linux/of_address.h> #include <linux/of_irq.h> +#include <linux/processor.h> #include <linux/slab.h> #include "common.h" @@ -23,14 +25,20 @@ * * @cinfo: SCMI channel info * @shmem: Transmit/Receive shared memory area - * @shmem_lock: Lock to protect access to Tx/Rx shared memory area + * @shmem_lock: Lock to protect access to Tx/Rx shared memory area. + * Used when NOT operating in atomic mode. + * @inflight: Atomic flag to protect access to Tx/Rx shared memory area. + * Used when operating in atomic mode. * @func_id: smc/hvc call function id */ struct scmi_smc { struct scmi_chan_info *cinfo; struct scmi_shared_mem __iomem *shmem; + /* Protect access to shmem area */ struct mutex shmem_lock; +#define INFLIGHT_NONE MSG_TOKEN_MAX + atomic_t inflight; u32 func_id; }; @@ -54,6 +62,41 @@ static bool smc_chan_available(struct device *dev, int idx) return true; } +static inline void smc_channel_lock_init(struct scmi_smc *scmi_info) +{ + if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE)) + atomic_set(&scmi_info->inflight, INFLIGHT_NONE); + else + mutex_init(&scmi_info->shmem_lock); +} + +static bool smc_xfer_inflight(struct scmi_xfer *xfer, atomic_t *inflight) +{ + int ret; + + ret = atomic_cmpxchg(inflight, INFLIGHT_NONE, xfer->hdr.seq); + + return ret == INFLIGHT_NONE; +} + +static inline void +smc_channel_lock_acquire(struct scmi_smc *scmi_info, + struct scmi_xfer *xfer __maybe_unused) +{ + if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE)) + spin_until_cond(smc_xfer_inflight(xfer, &scmi_info->inflight)); + else + mutex_lock(&scmi_info->shmem_lock); +} + +static inline void smc_channel_lock_release(struct scmi_smc *scmi_info) +{ + if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE)) + atomic_set(&scmi_info->inflight, INFLIGHT_NONE); + else + mutex_unlock(&scmi_info->shmem_lock); +} + static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev, bool tx) { @@ -114,7 +157,7 @@ static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev, scmi_info->func_id = func_id; scmi_info->cinfo = cinfo; - mutex_init(&scmi_info->shmem_lock); + smc_channel_lock_init(scmi_info); cinfo->transport_info = scmi_info; return 0; @@ -140,10 +183,10 @@ static int smc_send_message(struct scmi_chan_info *cinfo, struct arm_smccc_res res; /* - * Channel lock will be released only once response has been + * Channel will be released only once response has been * surely fully retrieved, so after .mark_txdone() */ - mutex_lock(&scmi_info->shmem_lock); + smc_channel_lock_acquire(scmi_info, xfer); shmem_tx_prepare(scmi_info->shmem, xfer); @@ -151,7 +194,7 @@ static int smc_send_message(struct scmi_chan_info *cinfo, /* Only SMCCC_RET_NOT_SUPPORTED is valid error code */ if (res.a0) { - mutex_unlock(&scmi_info->shmem_lock); + smc_channel_lock_release(scmi_info); return -EOPNOTSUPP; } @@ -170,7 +213,7 @@ static void smc_mark_txdone(struct scmi_chan_info *cinfo, int ret) { struct scmi_smc *scmi_info = cinfo->transport_info; - mutex_unlock(&scmi_info->shmem_lock); + smc_channel_lock_release(scmi_info); } static const struct scmi_transport_ops scmi_smc_ops = { @@ -196,4 +239,5 @@ const struct scmi_desc scmi_smc_desc = { * from the shared memory area. */ .sync_cmds_completed_on_ret = true, + .atomic_enabled = IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE), }; |