drm/imagination: Use pwrseq for TH1520 GPU power management

Update the Imagination PVR DRM driver to leverage the pwrseq framework
for managing the complex power sequence of the GPU on the T-HEAD TH1520
SoC.

To cleanly separate platform-specific logic from the generic driver,
this patch introduces an `init` callback to the `pwr_power_sequence_ops`
struct. This allows for different power management strategies to be
selected at probe time based on the device's compatible string.

A `pvr_device_data` struct, associated with each compatible in the
of_device_id table, points to the appropriate ops table (manual or
pwrseq).

At probe time, the driver now calls the `->init()` op. For pwrseq-based
platforms, this callback calls `devm_pwrseq_get("gpu-power")`, deferring
probe if the sequencer is not yet available. For other platforms, it
falls back to the existing manual clock and reset handling. The runtime
PM callbacks continue to call the appropriate functions via the ops
table.

Signed-off-by: Michal Wilczynski <m.wilczynski@samsung.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Matt Coster <matt.coster@imgtec.com>
Link: https://lore.kernel.org/r/20250822-apr_14_for_sending-v13-1-af656f7cc6c3@samsung.com
Signed-off-by: Matt Coster <matt.coster@imgtec.com>

1 files changed, 118 insertions, 40 deletions

diff --git a/drivers/gpu/drm/imagination/pvr_power.c b/drivers/gpu/drm/imagination/pvr_power.c
index 187a07e0bd9a..c6e7ff9e935d 100644
--- a/drivers/gpu/drm/imagination/pvr_power.c
+++ b/drivers/gpu/drm/imagination/pvr_power.c
@@ -18,6 +18,7 @@
 #include <linux/platform_device.h>
 #include <linux/pm_domain.h>
 #include <linux/pm_runtime.h>
+#include <linux/pwrseq/consumer.h>
 #include <linux/reset.h>
 #include <linux/timer.h>
 #include <linux/types.h>
@@ -234,6 +235,118 @@ pvr_watchdog_init(struct pvr_device *pvr_dev)
 	return 0;
 }
 
+static int pvr_power_init_manual(struct pvr_device *pvr_dev)
+{
+	struct drm_device *drm_dev = from_pvr_device(pvr_dev);
+	struct reset_control *reset;
+
+	reset = devm_reset_control_get_optional_exclusive(drm_dev->dev, NULL);
+	if (IS_ERR(reset))
+		return dev_err_probe(drm_dev->dev, PTR_ERR(reset),
+				     "failed to get gpu reset line\n");
+
+	pvr_dev->reset = reset;
+
+	return 0;
+}
+
+static int pvr_power_on_sequence_manual(struct pvr_device *pvr_dev)
+{
+	int err;
+
+	err = clk_prepare_enable(pvr_dev->core_clk);
+	if (err)
+		return err;
+
+	err = clk_prepare_enable(pvr_dev->sys_clk);
+	if (err)
+		goto err_core_clk_disable;
+
+	err = clk_prepare_enable(pvr_dev->mem_clk);
+	if (err)
+		goto err_sys_clk_disable;
+
+	/*
+	 * According to the hardware manual, a delay of at least 32 clock
+	 * cycles is required between de-asserting the clkgen reset and
+	 * de-asserting the GPU reset. Assuming a worst-case scenario with
+	 * a very high GPU clock frequency, a delay of 1 microsecond is
+	 * sufficient to ensure this requirement is met across all
+	 * feasible GPU clock speeds.
+	 */
+	udelay(1);
+
+	err = reset_control_deassert(pvr_dev->reset);
+	if (err)
+		goto err_mem_clk_disable;
+
+	return 0;
+
+err_mem_clk_disable:
+	clk_disable_unprepare(pvr_dev->mem_clk);
+
+err_sys_clk_disable:
+	clk_disable_unprepare(pvr_dev->sys_clk);
+
+err_core_clk_disable:
+	clk_disable_unprepare(pvr_dev->core_clk);
+
+	return err;
+}
+
+static int pvr_power_off_sequence_manual(struct pvr_device *pvr_dev)
+{
+	int err;
+
+	err = reset_control_assert(pvr_dev->reset);
+
+	clk_disable_unprepare(pvr_dev->mem_clk);
+	clk_disable_unprepare(pvr_dev->sys_clk);
+	clk_disable_unprepare(pvr_dev->core_clk);
+
+	return err;
+}
+
+const struct pvr_power_sequence_ops pvr_power_sequence_ops_manual = {
+	.init = pvr_power_init_manual,
+	.power_on = pvr_power_on_sequence_manual,
+	.power_off = pvr_power_off_sequence_manual,
+};
+
+static int pvr_power_init_pwrseq(struct pvr_device *pvr_dev)
+{
+	struct device *dev = from_pvr_device(pvr_dev)->dev;
+
+	pvr_dev->pwrseq = devm_pwrseq_get(dev, "gpu-power");
+	if (IS_ERR(pvr_dev->pwrseq)) {
+		/*
+		 * This platform requires a sequencer. If we can't get it, we
+		 * must return the error (including -EPROBE_DEFER to wait for
+		 * the provider to appear)
+		 */
+		return dev_err_probe(dev, PTR_ERR(pvr_dev->pwrseq),
+				     "Failed to get required power sequencer\n");
+	}
+
+	return 0;
+}
+
+static int pvr_power_on_sequence_pwrseq(struct pvr_device *pvr_dev)
+{
+	return pwrseq_power_on(pvr_dev->pwrseq);
+}
+
+static int pvr_power_off_sequence_pwrseq(struct pvr_device *pvr_dev)
+{
+	return pwrseq_power_off(pvr_dev->pwrseq);
+}
+
+const struct pvr_power_sequence_ops pvr_power_sequence_ops_pwrseq = {
+	.init = pvr_power_init_pwrseq,
+	.power_on = pvr_power_on_sequence_pwrseq,
+	.power_off = pvr_power_off_sequence_pwrseq,
+};
+
 int
 pvr_power_device_suspend(struct device *dev)
 {
@@ -252,11 +365,7 @@ pvr_power_device_suspend(struct device *dev)
 			goto err_drm_dev_exit;
 	}
 
-	clk_disable_unprepare(pvr_dev->mem_clk);
-	clk_disable_unprepare(pvr_dev->sys_clk);
-	clk_disable_unprepare(pvr_dev->core_clk);
-
-	err = reset_control_assert(pvr_dev->reset);
+	err = pvr_dev->device_data->pwr_ops->power_off(pvr_dev);
 
 err_drm_dev_exit:
 	drm_dev_exit(idx);
@@ -276,53 +385,22 @@ pvr_power_device_resume(struct device *dev)
 	if (!drm_dev_enter(drm_dev, &idx))
 		return -EIO;
 
-	err = clk_prepare_enable(pvr_dev->core_clk);
+	err = pvr_dev->device_data->pwr_ops->power_on(pvr_dev);
 	if (err)
 		goto err_drm_dev_exit;
 
-	err = clk_prepare_enable(pvr_dev->sys_clk);
-	if (err)
-		goto err_core_clk_disable;
-
-	err = clk_prepare_enable(pvr_dev->mem_clk);
-	if (err)
-		goto err_sys_clk_disable;
-
-	/*
-	 * According to the hardware manual, a delay of at least 32 clock
-	 * cycles is required between de-asserting the clkgen reset and
-	 * de-asserting the GPU reset. Assuming a worst-case scenario with
-	 * a very high GPU clock frequency, a delay of 1 microsecond is
-	 * sufficient to ensure this requirement is met across all
-	 * feasible GPU clock speeds.
-	 */
-	udelay(1);
-
-	err = reset_control_deassert(pvr_dev->reset);
-	if (err)
-		goto err_mem_clk_disable;
-
 	if (pvr_dev->fw_dev.booted) {
 		err = pvr_power_fw_enable(pvr_dev);
 		if (err)
-			goto err_reset_assert;
+			goto err_power_off;
 	}
 
 	drm_dev_exit(idx);
 
 	return 0;
 
-err_reset_assert:
-	reset_control_assert(pvr_dev->reset);
-
-err_mem_clk_disable:
-	clk_disable_unprepare(pvr_dev->mem_clk);
-
-err_sys_clk_disable:
-	clk_disable_unprepare(pvr_dev->sys_clk);
-
-err_core_clk_disable:
-	clk_disable_unprepare(pvr_dev->core_clk);
+err_power_off:
+	pvr_dev->device_data->pwr_ops->power_off(pvr_dev);
 
 err_drm_dev_exit:
 	drm_dev_exit(idx);