Commit eaca7ef8 authored by Sudeep Holla's avatar Sudeep Holla
Browse files

firmware: arm_ffa: Add support for FFA_YIELD in direct messaging 



Successful completion of both direct messaging function can be indicated
through an invocation of FFA_YIELD or GGA_INTERRUPT by the callee.

FFA_INTERRUPT indicates that the direct request was interrupted and must
be resumed through the FFA_RUN interface which is already done in the
driver.

FFA_YIELD indicates that the receiver endpoint has transitioned to the
blocked runtime state and must be resumed through the FFA_RUN interface.
However, the way receiver endpoint gets unblocked is implementation
defined. So, the driver just sleeps for 1 - 2ms and issues FFA_RUN. It
can return to the caller with FFA_YIELD is the receiver endpoint is still
blocked.

Message-Id: <20240820-ffa_v1-2-v2-6-18c0c5f3c65e@arm.com>
Signed-off-by: default avatarSudeep Holla <sudeep.holla@arm.com>
parent aaef3bc9

drivers/firmware/arm_ffa/driver.c

+15 −8
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ 
#include <linux/arm_ffa.h>

#include <linux/bitfield.h>

#include <linux/cpuhotplug.h>

#include <linux/delay.h>

#include <linux/device.h>

#include <linux/hashtable.h>

#include <linux/interrupt.h>
@@ -397,6 +398,18 @@ static int ffa_id_get(u16 *vm_id) 
	return 0;

}



static inline void ffa_msg_send_wait_for_completion(ffa_value_t *ret)

{

	while (ret->a0 == FFA_INTERRUPT || ret->a0 == FFA_YIELD) {

		if (ret->a0 == FFA_YIELD)

			fsleep(1000);



		invoke_ffa_fn((ffa_value_t){

			      .a0 = FFA_RUN, .a1 = ret->a1,

			      }, ret);

	}

}



static int ffa_msg_send_direct_req(u16 src_id, u16 dst_id, bool mode_32bit,

				   struct ffa_send_direct_data *data)

{
@@ -417,10 +430,7 @@ static int ffa_msg_send_direct_req(u16 src_id, u16 dst_id, bool mode_32bit, 
		      .a6 = data->data3, .a7 = data->data4,

		      }, &ret);



	while (ret.a0 == FFA_INTERRUPT)

		invoke_ffa_fn((ffa_value_t){

			      .a0 = FFA_RUN, .a1 = ret.a1,

			      }, &ret);

	ffa_msg_send_wait_for_completion(&ret);



	if (ret.a0 == FFA_ERROR)

		return ffa_to_linux_errno((int)ret.a2);
@@ -482,10 +492,7 @@ static int ffa_msg_send_direct_req2(u16 src_id, u16 dst_id, const uuid_t *uuid, 


	invoke_ffa_fn(args, &ret);



	while (ret.a0 == FFA_INTERRUPT)

		invoke_ffa_fn((ffa_value_t){

			      .a0 = FFA_RUN, .a1 = ret.a1,

			      }, &ret);

	ffa_msg_send_wait_for_completion(&ret);



	if (ret.a0 == FFA_ERROR)

		return ffa_to_linux_errno((int)ret.a2);