Add support for the GLB_REQ.STATE field introduced in CSF v4.1+, which
replaces the HALT bit to provide finer control over the MCU state. This
change implements basic handling for transitioning the MCU between
ACTIVE and HALT states on Mali-G1 GPUs.

The update introduces new helpers to issue the state change requests,
poll for MCU halt completion, and restore the MCU to an active state
after halting.

Reviewed-by: Steven Price <[email protected]>
Signed-off-by: Karunika Choo <[email protected]>
---
v4:
 * Picked up R-b from Steve.
v3:
 * Fixed missed CSF_IFACE_VERSION check with pathor_fw_has_glb_state().
v2:
 * Reduced MCU_HALT_TIMEOUT_US to 1 second.
 * Wrap the CSG_IFACE_VERSION checks for v4.1.0 with
   panthor_fw_has_glb_state().
 * Removed use of undefined panthor_fw_csf_version() MACRO.
---
 drivers/gpu/drm/panthor/panthor_fw.c | 89 +++++++++++++++++++++++-----
 drivers/gpu/drm/panthor/panthor_fw.h |  7 +++
 2 files changed, 80 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_fw.c 
b/drivers/gpu/drm/panthor/panthor_fw.c
index e6c39c70d348..fb1f69ef76fb 100644
--- a/drivers/gpu/drm/panthor/panthor_fw.c
+++ b/drivers/gpu/drm/panthor/panthor_fw.c
@@ -33,6 +33,7 @@
 #define PROGRESS_TIMEOUT_SCALE_SHIFT           10
 #define IDLE_HYSTERESIS_US                     800
 #define PWROFF_HYSTERESIS_US                   10000
+#define MCU_HALT_TIMEOUT_US                    (1ULL * USEC_PER_SEC)

 /**
  * struct panthor_fw_binary_hdr - Firmware binary header.
@@ -317,6 +318,13 @@ panthor_fw_get_cs_iface(struct panthor_device *ptdev, u32 
csg_slot, u32 cs_slot)
        return &ptdev->fw->iface.streams[csg_slot][cs_slot];
 }

+static bool panthor_fw_has_glb_state(struct panthor_device *ptdev)
+{
+       struct panthor_fw_global_iface *glb_iface = 
panthor_fw_get_glb_iface(ptdev);
+
+       return glb_iface->control->version >= CSF_IFACE_VERSION(4, 1, 0);
+}
+
 /**
  * panthor_fw_conv_timeout() - Convert a timeout into a cycle-count
  * @ptdev: Device.
@@ -996,6 +1004,9 @@ static void panthor_fw_init_global_iface(struct 
panthor_device *ptdev)
                                         GLB_IDLE_EN |
                                         GLB_IDLE;

+       if (panthor_fw_has_glb_state(ptdev))
+               glb_iface->input->ack_irq_mask |= GLB_STATE_MASK;
+
        panthor_fw_update_reqs(glb_iface, req, GLB_IDLE_EN, GLB_IDLE_EN);
        panthor_fw_toggle_reqs(glb_iface, req, ack,
                               GLB_CFG_ALLOC_EN |
@@ -1069,6 +1080,54 @@ static void panthor_fw_stop(struct panthor_device *ptdev)
                drm_err(&ptdev->base, "Failed to stop MCU");
 }

+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, MCU_STATUS) == MCU_STATUS_HALT;
+
+       if (panthor_fw_has_glb_state(ptdev))
+               halted &= (GLB_STATE_GET(glb_iface->output->ack) == 
GLB_STATE_HALT);
+
+       return halted;
+}
+
+static void panthor_fw_halt_mcu(struct panthor_device *ptdev)
+{
+       struct panthor_fw_global_iface *glb_iface = 
panthor_fw_get_glb_iface(ptdev);
+
+       if (panthor_fw_has_glb_state(ptdev))
+               panthor_fw_update_reqs(glb_iface, req, 
GLB_STATE(GLB_STATE_HALT), GLB_STATE_MASK);
+       else
+               panthor_fw_update_reqs(glb_iface, req, GLB_HALT, GLB_HALT);
+
+       gpu_write(ptdev, CSF_DOORBELL(CSF_GLB_DOORBELL_ID), 1);
+}
+
+static bool panthor_fw_wait_mcu_halted(struct panthor_device *ptdev)
+{
+       bool halted = false;
+
+       if (read_poll_timeout_atomic(panthor_fw_mcu_halted, halted, halted, 10,
+                                    MCU_HALT_TIMEOUT_US, 0, ptdev)) {
+               drm_warn(&ptdev->base, "Timed out waiting for MCU to halt");
+               return false;
+       }
+
+       return true;
+}
+
+static void panthor_fw_mcu_set_active(struct panthor_device *ptdev)
+{
+       struct panthor_fw_global_iface *glb_iface = 
panthor_fw_get_glb_iface(ptdev);
+
+       if (panthor_fw_has_glb_state(ptdev))
+               panthor_fw_update_reqs(glb_iface, req, 
GLB_STATE(GLB_STATE_ACTIVE), GLB_STATE_MASK);
+       else
+               panthor_fw_update_reqs(glb_iface, req, 0, GLB_HALT);
+}
+
 /**
  * panthor_fw_pre_reset() - Call before a reset.
  * @ptdev: Device.
@@ -1085,19 +1144,13 @@ void panthor_fw_pre_reset(struct panthor_device *ptdev, 
bool on_hang)
        ptdev->reset.fast = false;

        if (!on_hang) {
-               struct panthor_fw_global_iface *glb_iface = 
panthor_fw_get_glb_iface(ptdev);
-               u32 status;
-
-               panthor_fw_update_reqs(glb_iface, req, GLB_HALT, GLB_HALT);
-               gpu_write(ptdev, CSF_DOORBELL(CSF_GLB_DOORBELL_ID), 1);
-               if (!gpu_read_poll_timeout(ptdev, MCU_STATUS, status,
-                                          status == MCU_STATUS_HALT, 10,
-                                          100000)) {
-                       ptdev->reset.fast = true;
-               } else {
+               panthor_fw_halt_mcu(ptdev);
+               if (!panthor_fw_wait_mcu_halted(ptdev))
                        drm_warn(&ptdev->base, "Failed to cleanly suspend MCU");
-               }
+               else
+                       ptdev->reset.fast = true;
        }
+       panthor_fw_stop(ptdev);

        panthor_job_irq_suspend(&ptdev->fw->irq);
 }
@@ -1125,14 +1178,14 @@ int panthor_fw_post_reset(struct panthor_device *ptdev)
                 */
                panthor_reload_fw_sections(ptdev, true);
        } else {
-               /* The FW detects 0 -> 1 transitions. Make sure we reset
-                * the HALT bit before the FW is rebooted.
+               /*
+                * If the FW was previously successfully halted in the pre-reset
+                * operation, we need to transition it to active again before
+                * the FW is rebooted.
                 * This is not needed on a slow reset because FW sections are
                 * re-initialized.
                 */
-               struct panthor_fw_global_iface *glb_iface = 
panthor_fw_get_glb_iface(ptdev);
-
-               panthor_fw_update_reqs(glb_iface, req, 0, GLB_HALT);
+               panthor_fw_mcu_set_active(ptdev);
        }

        ret = panthor_fw_start(ptdev);
@@ -1170,6 +1223,10 @@ void panthor_fw_unplug(struct panthor_device *ptdev)
                if (ptdev->fw->irq.irq)
                        panthor_job_irq_suspend(&ptdev->fw->irq);

+               panthor_fw_halt_mcu(ptdev);
+               if (!panthor_fw_wait_mcu_halted(ptdev))
+                       drm_warn(&ptdev->base, "Failed to halt MCU on unplug");
+
                panthor_fw_stop(ptdev);
        }

diff --git a/drivers/gpu/drm/panthor/panthor_fw.h 
b/drivers/gpu/drm/panthor/panthor_fw.h
index 6598d96c6d2a..a19ed48b2d0b 100644
--- a/drivers/gpu/drm/panthor/panthor_fw.h
+++ b/drivers/gpu/drm/panthor/panthor_fw.h
@@ -214,6 +214,13 @@ struct panthor_fw_global_input_iface {
 #define GLB_FWCFG_UPDATE                       BIT(9)
 #define GLB_IDLE_EN                            BIT(10)
 #define GLB_SLEEP                              BIT(12)
+#define GLB_STATE_MASK                         GENMASK(14, 12)
+#define   GLB_STATE_ACTIVE                     0
+#define   GLB_STATE_HALT                       1
+#define   GLB_STATE_SLEEP                      2
+#define   GLB_STATE_SUSPEND                    3
+#define   GLB_STATE(x)                         (((x) << 12) & GLB_STATE_MASK)
+#define   GLB_STATE_GET(x)                     (((x) & GLB_STATE_MASK) >> 12)
 #define GLB_INACTIVE_COMPUTE                   BIT(20)
 #define GLB_INACTIVE_FRAGMENT                  BIT(21)
 #define GLB_INACTIVE_TILER                     BIT(22)
--
2.49.0

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