[PATCH v3 7/8] drm/panthor: Use a local iomem base for firmware control registers

Karunika Choo
2026-04-27T16:00:58Z

Add an MCU_CONTROL-local iomem pointer to struct panthor_fw and use it
for firmware control and status register accesses.

Job interrupt accesses continue to go through the IRQ-local base, while
doorbell writes stay on the device-wide mapping because they live
outside the MCU control window. This keeps firmware register accesses
scoped to the component that owns them.

No functional change intended.

v3:
- Pick up R-bs from Liviu and Steve
v2:
- Pick up Ack from Boris.

Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Acked-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Karunika Choo <karunika.choo@arm.com>
---
drivers/gpu/drm/panthor/panthor_fw.c | 20 +++++++++++++-------
drivers/gpu/drm/panthor/panthor_fw_regs.h | 11 ++++-------
2 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
index 73ef07a37e22..986151681b24 100644
--- a/drivers/gpu/drm/panthor/panthor_fw.c
+++ b/drivers/gpu/drm/panthor/panthor_fw.c
@@ -234,6 +234,9 @@ struct panthor_fw_iface {
* struct panthor_fw - Firmware management
*/
struct panthor_fw {
+ /** @iomem: CPU mapping of MCU_CONTROL iomem region */
+ void __iomem *iomem;
+
/** @vm: MCU VM. */
struct panthor_vm *vm;

@@ -1069,7 +1072,7 @@ static void panthor_job_irq_handler(struct panthor_device *ptdev, u32 status)
if (tracepoint_enabled(gpu_job_irq))
start = ktime_get_ns();

- gpu_write(ptdev->iomem, JOB_INT_CLEAR, status);
+ gpu_write(ptdev->fw->irq.iomem, INT_CLEAR, status);

if (!ptdev->fw->booted && (status & JOB_INT_GLOBAL_IF))
ptdev->fw->booted = true;
@@ -1092,18 +1095,19 @@ PANTHOR_IRQ_HANDLER(job, panthor_job_irq_handler);

static int panthor_fw_start(struct panthor_device *ptdev)
{
+ struct panthor_fw *fw = ptdev->fw;
bool timedout = false;

ptdev->fw->booted = false;
panthor_job_irq_enable_events(&ptdev->fw->irq, ~0);
panthor_job_irq_resume(&ptdev->fw->irq);
- gpu_write(ptdev->iomem, MCU_CONTROL, MCU_CONTROL_AUTO);
+ gpu_write(fw->iomem, MCU_CONTROL, MCU_CONTROL_AUTO);

if (!wait_event_timeout(ptdev->fw->req_waitqueue,
ptdev->fw->booted,
msecs_to_jiffies(1000))) {
if (!ptdev->fw->booted &&
- !(gpu_read(ptdev->iomem, JOB_INT_STAT) & JOB_INT_GLOBAL_IF))
+ !(gpu_read(fw->irq.iomem, INT_STAT) & JOB_INT_GLOBAL_IF))
timedout = true;
}

@@ -1114,7 +1118,7 @@ static int panthor_fw_start(struct panthor_device *ptdev)
[MCU_STATUS_HALT] = "halt",
[MCU_STATUS_FATAL] = "fatal",
};
- u32 status = gpu_read(ptdev->iomem, MCU_STATUS);
+ u32 status = gpu_read(fw->iomem, MCU_STATUS);

drm_err(&ptdev->base, "Failed to boot MCU (status=%s)",
status < ARRAY_SIZE(status_str) ? status_str[status] : "unknown");
@@ -1126,10 +1130,11 @@ static int panthor_fw_start(struct panthor_device *ptdev)

static void panthor_fw_stop(struct panthor_device *ptdev)
{
+ struct panthor_fw *fw = ptdev->fw;
u32 status;

- gpu_write(ptdev->iomem, MCU_CONTROL, MCU_CONTROL_DISABLE);
- if (gpu_read_poll_timeout(ptdev->iomem, MCU_STATUS, status,
+ gpu_write(fw->iomem, MCU_CONTROL, MCU_CONTROL_DISABLE);
+ if (gpu_read_poll_timeout(fw->iomem, MCU_STATUS, status,
status == MCU_STATUS_DISABLED, 10, 100000))
drm_err(&ptdev->base, "Failed to stop MCU");
}
@@ -1139,7 +1144,7 @@ static bool panthor_fw_mcu_halted(struct panthor_device *ptdev)
struct panthor_fw_global_iface *glb_iface = panthor_fw_get_glb_iface(ptdev);
bool halted;

- halted = gpu_read(ptdev->iomem, MCU_STATUS) == MCU_STATUS_HALT;
+ halted = gpu_read(ptdev->fw->iomem, MCU_STATUS) == MCU_STATUS_HALT;

if (panthor_fw_has_glb_state(ptdev))
halted &= (GLB_STATE_GET(glb_iface->output->ack) == GLB_STATE_HALT);
@@ -1461,6 +1466,7 @@ int panthor_fw_init(struct panthor_device *ptdev)
if (!fw)
return -ENOMEM;

+ fw->iomem = ptdev->iomem + MCU_CONTROL_BASE;
ptdev->fw = fw;
init_waitqueue_head(&fw->req_waitqueue);
INIT_LIST_HEAD(&fw->sections);
diff --git a/drivers/gpu/drm/panthor/panthor_fw_regs.h b/drivers/gpu/drm/panthor/panthor_fw_regs.h
index eeb41aff249b..b2e59cfc22b0 100644
--- a/drivers/gpu/drm/panthor/panthor_fw_regs.h
+++ b/drivers/gpu/drm/panthor/panthor_fw_regs.h
@@ -4,23 +4,20 @@
#ifndef __PANTHOR_FW_REGS_H__
#define __PANTHOR_FW_REGS_H__

-#define MCU_CONTROL 0x700
+#define MCU_CONTROL_BASE 0x700
+
+#define MCU_CONTROL 0x0
#define MCU_CONTROL_ENABLE 1
#define MCU_CONTROL_AUTO 2
#define MCU_CONTROL_DISABLE 0

-#define MCU_STATUS 0x704
+#define MCU_STATUS 0x4
#define MCU_STATUS_DISABLED 0
#define MCU_STATUS_ENABLED 1
#define MCU_STATUS_HALT 2
#define MCU_STATUS_FATAL 3

#define JOB_INT_BASE 0x1000
-
-#define JOB_INT_RAWSTAT 0x1000
-#define JOB_INT_CLEAR 0x1004
-#define JOB_INT_MASK 0x1008
-#define JOB_INT_STAT 0x100c
#define JOB_INT_GLOBAL_IF BIT(31)
#define JOB_INT_CSG_IF(x) BIT(x)

--
2.43.0